Papercup's V8 RX7
Discussion
I should be back at Craig's in a few weeks to finish off some stuff and fix the exhaust up. Hoepfully I'll get to drive the Rex he finished recently with the TR6060 box. Craig says its loads better.
Oh, I do have the auto diff. Your calculations seem spot on with the in-gear speeds; I was a whisker off the redline in 5th down the back straight at Goodwood, and the satnav claimed 140.
Still not sure where to go next; I could get a TR6060 or Magnum but the gear ratios are still screwed. This car wants a 3.3/3.4 diff really, then the gears would make more sense and 6th would be a true overdrive. I was looking at the gear ratios for the Corvette ZR-1 the other day; its geared for 205 in 5th, and 6th is just for MPG. With the power-to-weight of the Rex that makes more sense than what I have now (which is a gearbox I don't EVER even use 1st gear in, and I run out of puff at 140 as i hit the top of 5th and then 6th is a lifetime away.
Corvette ZR-1:
Gear Type Close Ratio 6-Speed Manual
Final Drive 3.42:1
1st Gear Ratio 2.29:1
2nd Gear Ratio 1.61:1
3rd Gear Ratio 1.21:1
4th Gear Ratio 1:1
5th Gear Ratio 0.81:1
6th Gear Ratio 0.67:1
Compared to what I have:
Final Drive 3.91:1
1st Gear Ratio 2.97:1
2nd Gear Ratio 2.07:1
3rd Gear Ratio 1.43:1
4th Gear Ratio 1:1
5th Gear Ratio 0.84:1
6th Gear Ratio 0.57:1
I can get a Magnum with those same ratios as the Corvette, the close ratio box.
Craig is working towards making a fitting kit for a Cobra diff, and you can have that in any ratio you want. Needs new half-shafts though (which Craig alwready has in his, and a Viper diff). Cobra diff looks a lot bigger than the Rex one buts its ally so actually weighs less.
One of those and a nice TR6060 or Magnum (whichever is smoother). Nice. The way forward?
Andy
Oh, I do have the auto diff. Your calculations seem spot on with the in-gear speeds; I was a whisker off the redline in 5th down the back straight at Goodwood, and the satnav claimed 140.
Still not sure where to go next; I could get a TR6060 or Magnum but the gear ratios are still screwed. This car wants a 3.3/3.4 diff really, then the gears would make more sense and 6th would be a true overdrive. I was looking at the gear ratios for the Corvette ZR-1 the other day; its geared for 205 in 5th, and 6th is just for MPG. With the power-to-weight of the Rex that makes more sense than what I have now (which is a gearbox I don't EVER even use 1st gear in, and I run out of puff at 140 as i hit the top of 5th and then 6th is a lifetime away.
Corvette ZR-1:
Gear Type Close Ratio 6-Speed Manual
Final Drive 3.42:1
1st Gear Ratio 2.29:1
2nd Gear Ratio 1.61:1
3rd Gear Ratio 1.21:1
4th Gear Ratio 1:1
5th Gear Ratio 0.81:1
6th Gear Ratio 0.67:1
Compared to what I have:
Final Drive 3.91:1
1st Gear Ratio 2.97:1
2nd Gear Ratio 2.07:1
3rd Gear Ratio 1.43:1
4th Gear Ratio 1:1
5th Gear Ratio 0.84:1
6th Gear Ratio 0.57:1
I can get a Magnum with those same ratios as the Corvette, the close ratio box.
Craig is working towards making a fitting kit for a Cobra diff, and you can have that in any ratio you want. Needs new half-shafts though (which Craig alwready has in his, and a Viper diff). Cobra diff looks a lot bigger than the Rex one buts its ally so actually weighs less.
One of those and a nice TR6060 or Magnum (whichever is smoother). Nice. The way forward?
Andy
Going further:
Check out Rockland Standard Gear and click on 'Tremec T56 Magnums Built to Son Of Tranzilla Specs...'
This is the people recommended to me by Craig; they built his T56 (back before the TR6060 and Magnum (which is TR-6060-based)) into something stronger after he killed it drag racing.
You can see they offer three choices. Check out the close ratio one (No.3). See how the ratios are almost exactly the same as the ZR-1 I put in the post above.
Combine with a Cobra diff at 3.42 (same as ZR-1 again) and my tyre profile at the back being 40, not the 35 you put, and that gives me:
Now THAT is food for thought.....
Check out Rockland Standard Gear and click on 'Tremec T56 Magnums Built to Son Of Tranzilla Specs...'
This is the people recommended to me by Craig; they built his T56 (back before the TR6060 and Magnum (which is TR-6060-based)) into something stronger after he killed it drag racing.
You can see they offer three choices. Check out the close ratio one (No.3). See how the ratios are almost exactly the same as the ZR-1 I put in the post above.
Combine with a Cobra diff at 3.42 (same as ZR-1 again) and my tyre profile at the back being 40, not the 35 you put, and that gives me:
Now THAT is food for thought.....
Not too bad, but I had a quickshifter on the Mazda box (and never drove it without) so that was hardly 'smooth'. It was precise though. You knew what gear you were going to get next. Sometimes I am not too sure with the V8, especially when you add heat to the 'box and there is a corner fast approaching. I had to make a real effort, a conscious effort, to slow my changes down and think hard about where the gear lever was going to go, especially from 5th don to 4th; otherwise I'd get 6th, then the gate, then 6, then the gate, then.......
I would say that I have less 'shunt' in the drivetrain with this V8 than I had with the rotary. I always thought my rotary drivetrain was slappy, and my big project for the year (this was the beginning of year 4 of ownership) was to replace whatever was needed to get it to drive without so much nasty shunt. I drove it everywhere on the clutch, like you do a big V-Twin motorbike in town. I grew to dislike it quite a lot [in town, or 'just pottering around], hence me just saying to Geff [at Re:Worx] 'this year that bloody slap gets fixed, I am sick of it, I don't care if I have to change every single mount and bush on the motor, gearbox, powerplant frames and diff but its getting sodding fixed this year'.
It blew up about two weeks later. I'm glad it let go before I did that lot!
I would say that I have less 'shunt' in the drivetrain with this V8 than I had with the rotary. I always thought my rotary drivetrain was slappy, and my big project for the year (this was the beginning of year 4 of ownership) was to replace whatever was needed to get it to drive without so much nasty shunt. I drove it everywhere on the clutch, like you do a big V-Twin motorbike in town. I grew to dislike it quite a lot [in town, or 'just pottering around], hence me just saying to Geff [at Re:Worx] 'this year that bloody slap gets fixed, I am sick of it, I don't care if I have to change every single mount and bush on the motor, gearbox, powerplant frames and diff but its getting sodding fixed this year'.
It blew up about two weeks later. I'm glad it let go before I did that lot!
carl0s said:
Hmm. Mine is hideous. I can feel take up of slack in the box when touching the throttle, and it sort of clashes into gear all the time except when the box is well and truly warmed up, which isn't often. This car is a daily short-distance driver.
I may just replace some gears and synchros, but I fear it would be a wasted effort. I have a fresh 1-2 synchro sat on the worktop though. I may buy a new 2nd and 3rd gear since the engagement dog teeth were worn pretty flat and I had to Dremel points back into them.
No, mine is not like that, definitely not the 'taking up the slack' thing you mention. We should meet and drive each others at some point; I was starting to think I'd been unlucky and got someone's well-worn crappy gearbox, but it sounds like yours is worse!I may just replace some gears and synchros, but I fear it would be a wasted effort. I have a fresh 1-2 synchro sat on the worktop though. I may buy a new 2nd and 3rd gear since the engagement dog teeth were worn pretty flat and I had to Dremel points back into them.
I need a gearbox oil cooler, and therefore a pump as well, and different ratios.....and I dont want to waste the money on this 'box. The TR-6060s are loads better, and Rockland's Magnums have carbon fibre shift rings etc to make the shift nicer.
I'd rather spend my money on something dserving, than throw money after this one.
mk1salami said:
Just read this from the start. What a beautifully executed build, and great all round car.
Just a thought - Why not add a slam panel cover / shroud to direct the air through the rad?
Because it doesn't appear I need to any more; see the post a few above this about the Goodwood trip. We'll see what high summer brings, but it was a warm day, and my gut feeling is the temperature woes are over. Just a thought - Why not add a slam panel cover / shroud to direct the air through the rad?
Water at 90, oil at 100. Seems pretty good to me. Those were maximum figures reached during the day, as held by the gauges; they were lower most of the time.
Bear in mind my car is different to every other Rex that Craig has done; I insisted on air-con and retaining the pop-ups. So I have a different (smaller) radiator and different mounting points.
Rex is now with Craig in Birmingham, along with a huuuge list of stuff to do.
I've remembered another problem we had at Goodwood; about halfway through the day we noticed the engine belt (power steering, alternator, air-con etc) on the front of the engine had hopped partly out of its tensioner, which had caused it to hop the same amount out of the power steering pulley as well, and move accordingly on the big wheel about halfway down the engine. It was still in the guide on the bottom wheel. The auto-tensioner doesn't like high revs apparently; Craig has seen this before. We popped it back in. It happened again just driving normally a few weeks later. I think the first time weakened the actual belt as I've given it no high revs or hard work since the track day (because of the exhaust problems), apart from a few blasts through a single gear.
So I ordered a manual tensioner off eBay and its arriving tomorrow, and will be sent up to Craig.
I'll get the list off Craig and put it up here, I can't be bothered to try and remember it all here, and it got bigger when I got there and got chatting, and another 2 things were added today as I remembered them!
Big discussion with Craig about diffs and gear ratios as well; plans are afoot to offer a fitting kit for an aftermarket diff (not sure which yet) that can be offered to not only V8 users but also rotary Rexes that drift and drag; the diff can be a weak point for them as well once you get about 450-odd horses.
I have been told to raise my rev limit to 7000, which I'll get to when i get Rex back (the mapper lives near me, so its easy). This will help a little with the speeds in each gear, but not much, and its a sticking plaster anyway. But I do enjoy revs so I'm all for it.
More soon.
Andy
I've remembered another problem we had at Goodwood; about halfway through the day we noticed the engine belt (power steering, alternator, air-con etc) on the front of the engine had hopped partly out of its tensioner, which had caused it to hop the same amount out of the power steering pulley as well, and move accordingly on the big wheel about halfway down the engine. It was still in the guide on the bottom wheel. The auto-tensioner doesn't like high revs apparently; Craig has seen this before. We popped it back in. It happened again just driving normally a few weeks later. I think the first time weakened the actual belt as I've given it no high revs or hard work since the track day (because of the exhaust problems), apart from a few blasts through a single gear.
So I ordered a manual tensioner off eBay and its arriving tomorrow, and will be sent up to Craig.
I'll get the list off Craig and put it up here, I can't be bothered to try and remember it all here, and it got bigger when I got there and got chatting, and another 2 things were added today as I remembered them!
Big discussion with Craig about diffs and gear ratios as well; plans are afoot to offer a fitting kit for an aftermarket diff (not sure which yet) that can be offered to not only V8 users but also rotary Rexes that drift and drag; the diff can be a weak point for them as well once you get about 450-odd horses.
I have been told to raise my rev limit to 7000, which I'll get to when i get Rex back (the mapper lives near me, so its easy). This will help a little with the speeds in each gear, but not much, and its a sticking plaster anyway. But I do enjoy revs so I'm all for it.
More soon.
Andy
Rex is home 
First of all, someone mailed me about the clocks I'd used, and I've been remiss about details of them since they changed fairly recently. I started with Stack gauges (water temp & oil pressure), pictured earlier in the thread, to replace the original Mazda ones that are known to be a bit pants, but that was when I had a mechanical oil temperature gauge in the centre console. With the stereo install, the double-din head unit took that space, so I needed to move that oil temp gauge. So then I had the need for 3 gauges and only space in the dash for two. Mmm.
I bought a double-gauge holder, a carbon thingy, that goes where the stupid central dash speaker (that never has anything in) goes, but then found something nicer. (The carbon double gauge thingy is for sale if anyone wants it, its at Craig's (if he can find it...) and is still in its original packaging, unused). Oh, the mechanical oil temp gauge is there as well....anyone want one? I keep thinking I'll put that on the gearbox but I don't really want to know, its just another thing to worry about. I'd also then have to use the carbon dashboard gaugeholder as well, and I hate that whole japanese '37 gauges on my dashboard thing, oh and 7 up the A post, and 13 in the glovebox' thing that people do. Subtlety can be done with japanese cars, I feel the need to remark to people sometimes.
The Demon Tweeks catalogue showed me some by SPA Design, digital, and each gauge does two things. Expensive, but each gauge is basically like buying two normal gauges, so not that bad overall, and they are ridiculously programmable. I can tell them not to flash red lights when the oil pressure is low because the engine isn't running yet, that sort of thing. I can also program when lights come on, upper and lower thresholds, and many other things, more than I can remember or will probably ever need. They look good, and fit well:
The top one does oil pressure and oil temperature, the bottom one does fuel pressure and water temp. OK, the fuel pressure is kind of useless as it sits at just over 4 bar all the time, but still. I can also change the colour, brightness, contrast. This last bit is particularly cool as I have configured them to be the same colour and brightness as the original Rex dash lights, so when you switch the lights on:
Groovy.
OK, now back to the reason I went; to pick up the car after a whole bunch of bits and bobs were sorted:
1. Air-con now works. Quick re-cap; we had to use an old compressor from a 98/99 'f-body' Camaro (same as the sump kit) because the 2006 one from this motor would foul the chassis. Hindsight told us we should have had it serviced before we put it on as it crapped itself immediately. This was all late last year and I didn't care as it was cold! Now its warm so it got pressurised up and....works perfectly! Switch on air-con and the compressor kicks in, the fans on the air-con rad start up and chilly air comes out. Great news; at Goodwood after continued running the whole chassis gets hot, the roll cage gets hot, the heat pours out either side of the centre-console by your thighs, its just uncomfortable. You can feel your feet getting all sweaty. Now I can leave the AC on, pointed downwards. We'll see how that goes; Nurburgring again in a few weeks, it looks like.
2. Rex's suffer with bump-steer if you lower them too much. They also suffer if you move the steering column slightly to stuff a V8 in the engine bay. Craig's specially-made bump-steer kit fixes all woes, and I'd missed the last batch. Now fitted:
3. The manual belt tensioner thingy mentioned in recent posts above arrived, and has been fitted. Craig remarked that my automatic one had got all weak and old; hence the belt jumping off. Makes the rest of the engine bay look old!
4. Fluids. While its there I had oil and filter changed (been almost a year, I guess), and the brake fluid flushed (been even longer, last done while it was a rotary), and new clutch fluid (always manky, due to GM putting the slave cylinder right next to the very hot gearbox and clutch).
5. At Goodwood I'd managed to blow the exhaust apart, at where the mid-box connects to the connecting pipe to the rear-box. It was a ring clamp. So along with my long-term Rex philosophy of 'if it breaks, replace with something PROPER', this was changed for a flange with nuts and bolts:
and here's another with, strangely, Friar Tuck working on my car?
6. On the road recently I had noticed a strange screeching noise accompanying high revs. It came from behind me, and sounded like someone tearing thin sheets of metal, like huge tin cans opened out flat and then pulled apart. I would have put money on it being the tail-pipe, the internals of which I assumed had fallen to bits. It wasn't that. Craig opened it up and it was fine. He stuck some newer packing in it and put it back on. Then he noticed something I had got used to over the last 3 years; the metal slats that make up the double spoiler of my rear wing are a little loose. So he stripped it and tightened things up and used sealant stuff and now it doesn't vibrate when you shut the doors. I find it hard to believe this was the source of the frankly deafening noise (it drowned out everything in the car by the end of the Goodwood trackday, and was clearly audible to spectators trackside) but time will tell. I went to a quiet road nearby when I picked the car up and, ahem, used up some rear tyres, and I couldn't get a peep out of it. We'll see.
7. Oh, that will do. There were a few more ickle things but they aren't worth mentioning really, glove box catch not working well, that sort of thing.
While I was up there I also caught up with one of Craig's other builds, a Rex with a lucky owner who found an almost new engine and 'box from the 2010 Camaro SS. Normal LS3, but the real find was the new TR-6060 gearbox, the new version of my horrible old T56 that most LS owners are stuck with. I drove it. Same annoying ratios, but the shift was a revelation; short throw (like mine is with the quickshifter on it) but precise and positive. Now I hate my gearbox even more
Next thing? To use it some more. After that? Diff first, then gearbox, i reckon. News from the front line is that it won't be that long; a diff is on Craig's bench right now. I don't think I can say what its from (I would tell you, but I'd have to kill you, etc) but they are easy to source and the internals can be changed for a variety of manufacturers (Quaife, Kaaz, and several others), differing types of slipper (cones, etc) and most importantly, different ratios. They do a 3.45. From my plans above with close-ratios boxes and 3.42 diffs, thats close enough for me. Watch this space.
cheers
Andy
First of all, someone mailed me about the clocks I'd used, and I've been remiss about details of them since they changed fairly recently. I started with Stack gauges (water temp & oil pressure), pictured earlier in the thread, to replace the original Mazda ones that are known to be a bit pants, but that was when I had a mechanical oil temperature gauge in the centre console. With the stereo install, the double-din head unit took that space, so I needed to move that oil temp gauge. So then I had the need for 3 gauges and only space in the dash for two. Mmm.
I bought a double-gauge holder, a carbon thingy, that goes where the stupid central dash speaker (that never has anything in) goes, but then found something nicer. (The carbon double gauge thingy is for sale if anyone wants it, its at Craig's (if he can find it...) and is still in its original packaging, unused). Oh, the mechanical oil temp gauge is there as well....anyone want one? I keep thinking I'll put that on the gearbox but I don't really want to know, its just another thing to worry about. I'd also then have to use the carbon dashboard gaugeholder as well, and I hate that whole japanese '37 gauges on my dashboard thing, oh and 7 up the A post, and 13 in the glovebox' thing that people do. Subtlety can be done with japanese cars, I feel the need to remark to people sometimes.
The Demon Tweeks catalogue showed me some by SPA Design, digital, and each gauge does two things. Expensive, but each gauge is basically like buying two normal gauges, so not that bad overall, and they are ridiculously programmable. I can tell them not to flash red lights when the oil pressure is low because the engine isn't running yet, that sort of thing. I can also program when lights come on, upper and lower thresholds, and many other things, more than I can remember or will probably ever need. They look good, and fit well:
The top one does oil pressure and oil temperature, the bottom one does fuel pressure and water temp. OK, the fuel pressure is kind of useless as it sits at just over 4 bar all the time, but still. I can also change the colour, brightness, contrast. This last bit is particularly cool as I have configured them to be the same colour and brightness as the original Rex dash lights, so when you switch the lights on:
Groovy.
OK, now back to the reason I went; to pick up the car after a whole bunch of bits and bobs were sorted:
1. Air-con now works. Quick re-cap; we had to use an old compressor from a 98/99 'f-body' Camaro (same as the sump kit) because the 2006 one from this motor would foul the chassis. Hindsight told us we should have had it serviced before we put it on as it crapped itself immediately. This was all late last year and I didn't care as it was cold! Now its warm so it got pressurised up and....works perfectly! Switch on air-con and the compressor kicks in, the fans on the air-con rad start up and chilly air comes out. Great news; at Goodwood after continued running the whole chassis gets hot, the roll cage gets hot, the heat pours out either side of the centre-console by your thighs, its just uncomfortable. You can feel your feet getting all sweaty. Now I can leave the AC on, pointed downwards. We'll see how that goes; Nurburgring again in a few weeks, it looks like.
2. Rex's suffer with bump-steer if you lower them too much. They also suffer if you move the steering column slightly to stuff a V8 in the engine bay. Craig's specially-made bump-steer kit fixes all woes, and I'd missed the last batch. Now fitted:
3. The manual belt tensioner thingy mentioned in recent posts above arrived, and has been fitted. Craig remarked that my automatic one had got all weak and old; hence the belt jumping off. Makes the rest of the engine bay look old!
4. Fluids. While its there I had oil and filter changed (been almost a year, I guess), and the brake fluid flushed (been even longer, last done while it was a rotary), and new clutch fluid (always manky, due to GM putting the slave cylinder right next to the very hot gearbox and clutch).
5. At Goodwood I'd managed to blow the exhaust apart, at where the mid-box connects to the connecting pipe to the rear-box. It was a ring clamp. So along with my long-term Rex philosophy of 'if it breaks, replace with something PROPER', this was changed for a flange with nuts and bolts:
and here's another with, strangely, Friar Tuck working on my car?
6. On the road recently I had noticed a strange screeching noise accompanying high revs. It came from behind me, and sounded like someone tearing thin sheets of metal, like huge tin cans opened out flat and then pulled apart. I would have put money on it being the tail-pipe, the internals of which I assumed had fallen to bits. It wasn't that. Craig opened it up and it was fine. He stuck some newer packing in it and put it back on. Then he noticed something I had got used to over the last 3 years; the metal slats that make up the double spoiler of my rear wing are a little loose. So he stripped it and tightened things up and used sealant stuff and now it doesn't vibrate when you shut the doors. I find it hard to believe this was the source of the frankly deafening noise (it drowned out everything in the car by the end of the Goodwood trackday, and was clearly audible to spectators trackside) but time will tell. I went to a quiet road nearby when I picked the car up and, ahem, used up some rear tyres, and I couldn't get a peep out of it. We'll see.
7. Oh, that will do. There were a few more ickle things but they aren't worth mentioning really, glove box catch not working well, that sort of thing.
While I was up there I also caught up with one of Craig's other builds, a Rex with a lucky owner who found an almost new engine and 'box from the 2010 Camaro SS. Normal LS3, but the real find was the new TR-6060 gearbox, the new version of my horrible old T56 that most LS owners are stuck with. I drove it. Same annoying ratios, but the shift was a revelation; short throw (like mine is with the quickshifter on it) but precise and positive. Now I hate my gearbox even more
Next thing? To use it some more. After that? Diff first, then gearbox, i reckon. News from the front line is that it won't be that long; a diff is on Craig's bench right now. I don't think I can say what its from (I would tell you, but I'd have to kill you, etc) but they are easy to source and the internals can be changed for a variety of manufacturers (Quaife, Kaaz, and several others), differing types of slipper (cones, etc) and most importantly, different ratios. They do a 3.45. From my plans above with close-ratios boxes and 3.42 diffs, thats close enough for me. Watch this space.
cheers
Andy
blindswelledrat said:
Looks brilliant. Good stuff PC.
For those, like me, who arent particularly interested in the build (ergo reading 10 pages or so) wwould you mind giving us a bit of headline information such as power,torque, weight, weight comparisons of the engines.
Thanks for sharing
Thats the problem with the youth of today. They want it all now, and don't want to put the work in For those, like me, who arent particularly interested in the build (ergo reading 10 pages or so) wwould you mind giving us a bit of headline information such as power,torque, weight, weight comparisons of the engines.
Thanks for sharing
Without looking myself, vague power/torque figures are 470-odd of both bhp and torque and the car weighed around 70 kilos more when finished, though the weight was a little more forward of centre than it was before (which if you've seen where the rotary sits, will make sense).
Andy
blindswelledrat said:
THanks. Interesting and Im most jealous. Can you notice the weight shift in the handling?
Mostly, no. It was always my gut feeling that it wouldn't handle the same. I argued quite strongly on the Rex forum that it simply wasn't possible that something with a motor that weighs more, mounted further forward, would handle the same. I've proved it weighs more, I've proved the weight is further forward, what is surprising is how little difference it makes. Its a bloody missile on track, see a few pages ago for the full report. I expected it to feel a little 'blunted' but it truly doesn't. OK, I've only been to Goodwood so far, and only on a trackday, not a sprint. The fastest corner on the circuit was a little terrifying, but it always is at north of 130mph, and the geometry, we've since found, is not where it should have been. Considering how many times I've sprinted at Goodwood and Lydden Hill, doing the same now and comparing the timings will be the only way to tell, I suspect. Next I want to go to the new Snetterton as I was there on my track bike last week and its a great circuit now, and the new infield contains three 180 degree corners that will be a good test of the car. I get the feeling I will not so much care about relative speed, and will simply drift round them giggling like a child. The chicane at Goodwood used to be taken carefully and with trepidation; its an easy thing to overcook and spin there, and the rotary with its big turbo meant that the power came in a rush and if you went for it too early you had a big moment, which would ruin your time. Now in the V8 I do it in 3rd and its so easy and controllable to just give that pedal a little more of a press and hang the back end out, then tthrottle back and bring it back into line, and laugh at the simplicity of it. Those 180 degree corners are begging for it.
Thats the point; its different now and I love how it is now, and I shouldn't compare it as its a different car; I just can't help it as I know the car so well and its natural to compare things. Its not better or worse, its just.....different.
I do keep telling people and I'll repeat it here; its not an RX-7 any more. Its a V8 RX-7.
4packet said:
Great to see the updates on this thread. We’re currently building our car now and this build thread has been very useful.
On a non-engine related question, how do you get on with the SPG seats now the car is more of a road car? Sounds like you’ve built this car for the same usage we intend for ours. We need more head room and the only way I can see to do that is to fit bucket seats. Do you find these comfortable enough for ‘ringtrips and easy enough to live with for casual driving? I'm used to Recaro SR's, but don't think they will fit or be any lower.
I’ve also just realised that it is Max that has posted above that got me interested in the RX7. His 7:45 footage on BTG convinced me that there were gains to be had on track over my Supra!
You aren't going to want to hear this, but I find the SPGs quite uncomfortable over long distance. They give me lower back-ache. I actually run the standard cloth seats which are supremely comfortable (1900 in 4 days is my record, in comfort) and nice in hot weather too (I wouldn't put leather in that car if you paid me). I still have the SPGs and can swap them in and remove the wooden 'back-seat-unit' I've had built for when I trackday or sprint. On a non-engine related question, how do you get on with the SPG seats now the car is more of a road car? Sounds like you’ve built this car for the same usage we intend for ours. We need more head room and the only way I can see to do that is to fit bucket seats. Do you find these comfortable enough for ‘ringtrips and easy enough to live with for casual driving? I'm used to Recaro SR's, but don't think they will fit or be any lower.
I’ve also just realised that it is Max that has posted above that got me interested in the RX7. His 7:45 footage on BTG convinced me that there were gains to be had on track over my Supra!
redgriff500 said:
I can second that I ran them in my road / track car and I found they gripped you so tightly I got a numb bum !
No back ache though - you can get additional pads for lumbar etc
Mine are now in a dedicated track car.
Yes, numb bum also happens, but the dull aching in my lower back was worse. I actually found it was better if I pushed my bum all the way back, I seem to have a tendency to slide forward a little in them which means there is a gap between my lower back and the seat, and thats the problem; I'm leaning on my shoulders and the weight of everything above my waist is compressing my lower back as it has no support. If i force myself backwards its better, but it makes me sit very upright and its not my natural driving position. No back ache though - you can get additional pads for lumbar etc
Mine are now in a dedicated track car.
Standard Rex seats are just about the most comfortable thing I've ever experienced. I'd like to find some of the late cloth ones, the sort of dark metallic blue ones, they look lovely. But my standard cloth ones (with a bit of wear on the drivers thigh bolster, but no tears) will do fine.
Next time I go to the ring I'll be in more of a hurry and assuming I'm on my own I'll take an SPG for the passenger seat and then swap them over when I get there.....they are great for track driving.
4packet said:
Oh dear, possibly back to the drawing board then. The main target is to lower the seat base by at least 2", but haven't figured another way of doing this other than the bucket seat option. The stock seats don't hug my shoulders like I'm used to either.
Do you think adding some extra padding to the base and lower back (sculptured if necessary) of the SPG's would work?
perhaps....Do you think adding some extra padding to the base and lower back (sculptured if necessary) of the SPG's would work?
Its worth mentioning that Max had SPGs in his Rex and did numerous ring trips with no issues, and was surprised when i said I found them uncomfortable.....
Time for an update.
I can't be bothered to look back, but I think I outlined the original story of the aircon. You have to use an old compressor from an 'f-body' Camaro, 98-99 vintage, so we did, and it leaked.
So we got it rebuilt by Compressor Tech in Birmingham. But we didn't get it gassed and oiled up by them, another guy did it.
It worked for about two hours and then ate itself so badly it sounded like a cement mixer at the point you put in the gravel. Not kidding, you could hear it 30 feet away. This was the day of the Sunday Service at the BMW place in Bracknell. It worked all the way there and died at some point on the way home, but as I was on the motorway doing 90 and its not the quietest car in the world (ahem) so I didn't hear it until we stopped in traffic just outside Brighton and the funny noise made us investigate further. So at first it sounded like armageddon when you hit the AC switch and then it stopped making any noise, and stopped being cold (unsurprisingly).
So I took it off and sent it back to Compressor Tech. They said it had no usable parts left in it (!) and was scrap metal. Great. They also blamed the guy that gassed and oiled it up.
So I formed a new plan. This time, they do the whole thing from start to finish, including fitting things and gassing them up and doing the oil etc etc. SO if it screws up, it goes back to them! First they had to make a usable compressor.
So a few weeks back I went to Birmingham on Wednesday night, and on the Thursday morning, went to Craig's place (Dyno Torque, the place that built the car). We sent over two compressors he had lying about, then a third (!) and at last a decent compressor was made out of those 4 (the first two were rusty and shagged out, only the last one was any good really).
Craig and I took off the front bumper and one of the wings as that is where some of the components live.
(Craig ran the pipes into the inner wing and mounted the 'dryer' in there to save space under the bonnet - very tidy, but not easy to get to in the case of problems!).
Then it got trailered over to Compressor Tech and the next morning they fitted the new (and give them their credit, it looked new) compressor and basically made the whole thing go.
Back to Craig's to put the car back together again, and then home. Arrived home at 23.30 on the Friday night and started prepping the car for the Goodwood Sprint the next morning! Went to bed at 01.30 having swapped the seats for the Recaro buckets and hopefully thrown everything I need into the car!
To be continued......
I can't be bothered to look back, but I think I outlined the original story of the aircon. You have to use an old compressor from an 'f-body' Camaro, 98-99 vintage, so we did, and it leaked.
So we got it rebuilt by Compressor Tech in Birmingham. But we didn't get it gassed and oiled up by them, another guy did it.
It worked for about two hours and then ate itself so badly it sounded like a cement mixer at the point you put in the gravel. Not kidding, you could hear it 30 feet away. This was the day of the Sunday Service at the BMW place in Bracknell. It worked all the way there and died at some point on the way home, but as I was on the motorway doing 90 and its not the quietest car in the world (ahem) so I didn't hear it until we stopped in traffic just outside Brighton and the funny noise made us investigate further. So at first it sounded like armageddon when you hit the AC switch and then it stopped making any noise, and stopped being cold (unsurprisingly).
So I took it off and sent it back to Compressor Tech. They said it had no usable parts left in it (!) and was scrap metal. Great. They also blamed the guy that gassed and oiled it up.
So I formed a new plan. This time, they do the whole thing from start to finish, including fitting things and gassing them up and doing the oil etc etc. SO if it screws up, it goes back to them! First they had to make a usable compressor.
So a few weeks back I went to Birmingham on Wednesday night, and on the Thursday morning, went to Craig's place (Dyno Torque, the place that built the car). We sent over two compressors he had lying about, then a third (!) and at last a decent compressor was made out of those 4 (the first two were rusty and shagged out, only the last one was any good really).
Craig and I took off the front bumper and one of the wings as that is where some of the components live.
(Craig ran the pipes into the inner wing and mounted the 'dryer' in there to save space under the bonnet - very tidy, but not easy to get to in the case of problems!).
Then it got trailered over to Compressor Tech and the next morning they fitted the new (and give them their credit, it looked new) compressor and basically made the whole thing go.
Back to Craig's to put the car back together again, and then home. Arrived home at 23.30 on the Friday night and started prepping the car for the Goodwood Sprint the next morning! Went to bed at 01.30 having swapped the seats for the Recaro buckets and hopefully thrown everything I need into the car!
To be continued......
- * TEMPORARY INTERLUDE ***
We pondered what you could fit in that sort of room.....
Craig's car is running now, and shows what you can put there. Its already a 7 litre stroker with a forged bottom end, CNC-ed heads, custom intake, cam etc but he has gone a little further:
That would be two GT35Rs.
Its only mapped at wastegate spring pressure at the moment so is making a mere 722 at the wheels at 3500rpm
We went out in it on Thursday night. It is utterly breathtaking as a passenger. Then he let me drive it, and thats a really big thing as I don't think anyone has driven it but him at present. But I'm a little handy in mine (see Goodwood results to follow) so he trusted me enough I guess.
Words are not enough. You wouldn't believe that it would put the power down but it does. Found a small straight and gave it about half throttle in 2nd and it gripped fine, then changed to 3rd and floored it. Christ. Not one iota of wheelspin, even over a bump that I hit halfway through the gear (and made me feel like we'd take off, and then continue upwards into orbit). Ran put of space, very quickly.
Whats really amazing is you can drive it perfectly normally, like my car drives, under the turbos. Its just like driving any normal 1300kg 7-litre car (!). Then the turbos start to spool and the world just gets a bit silly.
Want.
Sf_Manta said:
Love this car 
Awesome write up7 litre V8 RX without the turbo's would be quick... Guess once the turbos' kicked in, it's a case of this:
tinker-27 said:
how many seconds did you win by was it 5 per lap !!
Yes, was a good day out at the Goodwood Sprint (which is run by the Brighton & Hove Motor Club, same people who do the Brighton Speed Trials. I'll be at the Speed Trials again this year, but on a bike for the second year running). A few years ago I did the entire sprint series and sprinted Goodwood three times in a few months, so I got used to the place. My fastest time at the last sprint was a 90 second (this is standing start, one lap). I did a 91.9 last week in practice, lost it completely with the 1st timed run and did a 93 (don't ask) and then came back with a 91.1 for the 2nd timed run. That was 5 seconds clear of the 2nd and 3rd placed cars (both did 96s).
But my tyres (888s) are screwed; they are the same ones I bought for that sprint series 2 years ago and now, two years later and numerous trips to birmingham and lots of road use (I've driven 5000 miles since the V8 went in) I was all over the place; very little grip at the back, it was like driving on marbles. Practice was downright scary, I had a few REAL moments and was shaking with adrenaline when I got out the car.
One of those cars in my class was a certain RX-7 with a V8 in it, the guy who has been doing a fair few sprints in it over the last year or so, a father and son team I've met before. To be fair to him, he hadn't been to Goodwood before. We had a good chat, and found common ground in our utter loathing of our gearboxes. On his second run he fluffed third going into the chicane and went straight through the cones, brakes locked solid. I did ask him to spray his car a different colour, as if he was going to bin his black V8 RX-7 with any regularity, people might think it was me. As you can imagine, he found this incredibly amusing
I wish I'd bought some new tyres if I'm honest, as I think I'd have equalled the rotary time. Next year I will buy some, and do all three Goodwood sprints, and see what I can do. I will also probably get back to Lydden, which I know very well, and see how my times compare.
I might even do the Speed Trials next year in the Rex, if a certain person gets there finger out with a replacement diff....but he's always messing about with his silly turbos! My Rexes rotary record there is a 12.6
Andy
p.s. At Snetterton next Wednesday for a trackday on the new circuit, with freshly fitted 888s on the back.
I found out an interesting thing recently. The Rex (as a rotary) shuts down its air-con at 5000rpm. The V8 is the same; the ECU shuts down the aircon at 5000rpm, and at wide-open-throttle. I thought this was to not affect the power, so you'd have it all when you had your foot down. It turns out that this is not the case.
Air-con compressors don't like it when the engine is bouncing off the limiter, while travelling sideways down the road. 5000rpm limit is there for a reason, they don't like 6500rpm.
My aircon wasn't set-up to run through the ECU
Oops.
It appears I blew a hole in the compressor.
Which showered the engine bay with its internals, and green goo.
Oh dear.
We have no more to rebuild, so I start looking at what a new one will cost. Compressor Tech in Birmingham quote me £600 for one from the states, new. I go on Yank eBay with the part number and find a new one for £278 and £55 delivery. Thats more like it.
Its the one for the Pontiac GTO, so will hit my chassis rails, so it still needs the rear housing from my one, which I send to CompTech in preparation. UPS were brilliant. Ordered on Thursday, it was in the UK Saturday morning. They called me on my mobile on Saturday afternoon to pay the customs charges (fifty quid) and it was delivered Monday morning. How's that? I sent it straight up to CompTech and they tweaked it, and then it came back down to me and was fitted. It was so new and tight it could not be turned by hand when on the car, and it almost kills the tickover when you push the button. Even better, you could freeze water with the cold air coming out the vents now. Very impressed.
To stop this happening again, I asked around and Blair (for it is he, above, talkin' 'bout wiring) is now ready to wire the whole thing through the ECU when the car is next up there. All I have to do now is remember not to leave it on while cocking about! Shouldn't be too hard, it being November....
No immediate plans to go up there, not just for this to be done. I have a few more things I want to do. While water temps are fine on track, the oil temps are a little high for my liking. No more than 100c around Goodwood was fine, but Snetterton (new circuit) is apparently a bit more of a test for the car and I was seeing 120c before doing a 'slow lap' to cool it down. It already has one of the standard Mazda oil coolers (see pics on page 5 of this thread) but its quite small (the Mazda has two as standard, but one came out to make room for the air filter), and there is a ton more room in that side pod. So I'm sourcing something chunkier for it, a Mocal I guess? Will have to get measuring.
Oh, and this is on is way from Roseville, Michigan...
.
.
Can you tell what it is yet?
Air-con compressors don't like it when the engine is bouncing off the limiter, while travelling sideways down the road. 5000rpm limit is there for a reason, they don't like 6500rpm.
My aircon wasn't set-up to run through the ECU
Oops.
It appears I blew a hole in the compressor.
Which showered the engine bay with its internals, and green goo.
Oh dear.
We have no more to rebuild, so I start looking at what a new one will cost. Compressor Tech in Birmingham quote me £600 for one from the states, new. I go on Yank eBay with the part number and find a new one for £278 and £55 delivery. Thats more like it.
Its the one for the Pontiac GTO, so will hit my chassis rails, so it still needs the rear housing from my one, which I send to CompTech in preparation. UPS were brilliant. Ordered on Thursday, it was in the UK Saturday morning. They called me on my mobile on Saturday afternoon to pay the customs charges (fifty quid) and it was delivered Monday morning. How's that? I sent it straight up to CompTech and they tweaked it, and then it came back down to me and was fitted. It was so new and tight it could not be turned by hand when on the car, and it almost kills the tickover when you push the button. Even better, you could freeze water with the cold air coming out the vents now. Very impressed.
To stop this happening again, I asked around and Blair (for it is he, above, talkin' 'bout wiring) is now ready to wire the whole thing through the ECU when the car is next up there. All I have to do now is remember not to leave it on while cocking about! Shouldn't be too hard, it being November....
No immediate plans to go up there, not just for this to be done. I have a few more things I want to do. While water temps are fine on track, the oil temps are a little high for my liking. No more than 100c around Goodwood was fine, but Snetterton (new circuit) is apparently a bit more of a test for the car and I was seeing 120c before doing a 'slow lap' to cool it down. It already has one of the standard Mazda oil coolers (see pics on page 5 of this thread) but its quite small (the Mazda has two as standard, but one came out to make room for the air filter), and there is a ton more room in that side pod. So I'm sourcing something chunkier for it, a Mocal I guess? Will have to get measuring.
Oh, and this is on is way from Roseville, Michigan...
.
.
Can you tell what it is yet?
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