1989 Corvette C4 6 Speed Manual
Discussion
FelixP said:
Thanks! Yeah I added the C6 in November as I wanted to try an LS powered car. work continental shifts so get blocks of time off and my usual week is 6-2, 2-10, 10-6 so I have free time when most people are working
How is the Lt1 compare to the LS1. Specifically sound-wise. I know in reality there is no comparison but would be keep to hear (I have a Procharged TPI)Edited by FelixP on Monday 18th July 14:48
My car isn't an LT1, it's a TPI car. However I changed the intake to the TPIS Miniram, which GM then based the design of the LT1 on. That makes a huge difference to the powerband, I haven't really lost anything low down but gained another 1000rpm at the top even with the stock cam. It's also much easier to R&R being a single piece. I imagine it would work very nice with a Procharger too.
https://tpis.com/products/1_man551?variant=2834255...
The LS has a different firing order to the small block chevy and you notice that on start up. It sounds a bit more racy somehow. I was surprised how eager the LS2 is to rev, I hang it out over 6k rpm often. Perhaps the character of the C4 will change with a lightweight flyweel though. The LS2 in the current tune probably has about 50% more power than the SBC in the C4. Although with a 6.3L stroker kit, decent heads & cam to suit it would match it no problem.
https://tpis.com/products/1_man551?variant=2834255...
The LS has a different firing order to the small block chevy and you notice that on start up. It sounds a bit more racy somehow. I was surprised how eager the LS2 is to rev, I hang it out over 6k rpm often. Perhaps the character of the C4 will change with a lightweight flyweel though. The LS2 in the current tune probably has about 50% more power than the SBC in the C4. Although with a 6.3L stroker kit, decent heads & cam to suit it would match it no problem.
FelixP said:
My car isn't an LT1, it's a TPI car. However I changed the intake to the TPIS Miniram, which GM then based the design of the LT1 on. That makes a huge difference to the powerband, I haven't really lost anything low down but gained another 1000rpm at the top even with the stock cam. It's also much easier to R&R being a single piece. I imagine it would work very nice with a Procharger too.
https://tpis.com/products/1_man551?variant=2834255...
The LS has a different firing order to the small block chevy and you notice that on start up. It sounds a bit more racy somehow. I was surprised how eager the LS2 is to rev, I hang it out over 6k rpm often. Perhaps the character of the C4 will change with a lightweight flyweel though. The LS2 in the current tune probably has about 50% more power than the SBC in the C4. Although with a 6.3L stroker kit, decent heads & cam to suit it would match it no problem.
Thanks Felix, interesting. Tempted by the Mini Ram but just want to try and keep the tpi look- despite the utter PITA it is. I' hoping the Big Mouth Intake and Accel runners will help.https://tpis.com/products/1_man551?variant=2834255...
The LS has a different firing order to the small block chevy and you notice that on start up. It sounds a bit more racy somehow. I was surprised how eager the LS2 is to rev, I hang it out over 6k rpm often. Perhaps the character of the C4 will change with a lightweight flyweel though. The LS2 in the current tune probably has about 50% more power than the SBC in the C4. Although with a 6.3L stroker kit, decent heads & cam to suit it would match it no problem.
What do you hope to gain from the flywheel- just easier spinning so to speak?
Love the red interior. The c4 looks ace, aged so well.
If you want to keep the TPI look I would go for the First intake then:
https://firstfuelinjection.com/
It's much bigger than the TPI & aftermarket bases & runners.
I want to get rid of the factory clutch arrangement. None of the throw out bearings are good quality now, so as soon as you replace them you're on borrowed time. The OEM dual mass helps to quieten the ZF6 gearbox but you can get a shim kit to help when using a lighter single piece flywheel. Since I'll have to get the gearbox out to change the throw out bearing, I'd rather just replace the whole lot with something much better engineered and not have to worry about it again.
https://firstfuelinjection.com/
It's much bigger than the TPI & aftermarket bases & runners.
I want to get rid of the factory clutch arrangement. None of the throw out bearings are good quality now, so as soon as you replace them you're on borrowed time. The OEM dual mass helps to quieten the ZF6 gearbox but you can get a shim kit to help when using a lighter single piece flywheel. Since I'll have to get the gearbox out to change the throw out bearing, I'd rather just replace the whole lot with something much better engineered and not have to worry about it again.
I went for the Ram hydraulic conversion with lightweight flywheel. Gave the car a quick clean up after sitting for ages. It fired straight up and runs nicely, off to get the clutch fitted and an MOT now. Looking unlikely I'll have it for Radwood this weekend but it was great to see it out of the car port for the first time in months and can't wait to get it back already!
I've just had a fun weekend with the C4 back on the road so thought I'd update this thread a bit.
The clutch replacement went okay to begin with. The old dual mass flywheel, which is unobtanium was well within spec so I sold it to a chap in Malta with a Callway twin turbo C4 to put on the shelf in case he needs it. The release bearing failed in a similar way to last time. So frustrating that a cheap part lets down the whole setup. You can't buy a quality one and even if you buy an expensive clutch/flywheel kit it still has the rubbish bearing.
The black tag German made ZF 6 box. This has different gear angles compared to the later blue tag USA made ones and was rated at 500ftlbs @ 50% capacity. Plenty of guys in the USA are putting double that through them!
Once it was fitted I drove the car around the yard and all seemed good. It went off to be MOT'd which it passed with flying colours and then I went to pick it up. Went to the petrol station obviously.
Then a few miles later the pedal went to the floor. One of the new hydraulic lines had split, inside the bell housing. My friend who fitted it turned up within about 30 minutes with a trailer to take it back. Much piss taking ensued as another friend going the other way spotted me and sent a photo to prove it. Then in work the next day a colleague who lives nearby came into work and said “you'll never guess who I saw yesterday on the A470?” to which everyone was in hysterics. A few days later it was back again with a better line made up.
I met up with some mates in Cardiff and we went for a little evening cruise down to the bay. Love the variety of old junk!
At Cowbridge cars & coffee I met up with another local C4 owner and then we both got out done when this turned up!
Then I went off to South America for a couple of weeks, which was fantastic. Had to lookout for Jaguars at the side of the road in Argentina, not the type with dodgy electrics either!
Then I got told off in Paraguay.
Back home the C4 had a niggly running issue, it was randomly cutting out but would then turn over really well with spark and fuel but not start for a bit. There didn't seem to be any pattern, hot, cold, under load, coasting etc. So I SORN'ed it.
I met up with Geraint also of PH with his MX5 although I was using the C6 a lot since it worked. Funny seeing the two cabrios together. I went to an American car meetup at Whocult doughnuts too and saw another C6 Z51 6 speed in Le Mans blue, apart from this one was a coupe. I'd seen it advertised before, it's a very nice car! Vesa also came to visit to have a go driving the C6. For an afternoon there was double trouble in my car port!
Dave (owner of Clive the Corvette) had asked me at the end of last year if I wanted to drive to the Sahara desert so I left the C4 behind once more. We had an incredible adventure and made it to the desert mostly drama free.
I helped out with the ubiquitous African detailing grit applicator.
Then I got told off again.
Back home again at the end of last month and with another week off coming up I thought I'd revisit the C4. I'm not sure if it's the demographic but there's still a busy forum that's good for advice. I thought I'd start with simple things first, I swapped the ECU for another reman one I'd bought before just because they're only about £80 and I thought it would be a useful for troubleshooting sometime. I swapped in my custom tune on the piggyback chip. The other thing I checked were the grounds on the bell housing These would have been disturbed during the clutch job. I managed to get another ½ turn on the bolt. It's funny working on it again, I've had it so long I don't need to look at any manuals and know what size the bolts are, if they're imperial or metric and so on. I'll have owned it 7 years next week! With that work done on Friday I taxed it! A friend came over in his Polo MK1 with a G40 1.3L supercharged swap to follow me to get some coffee and possibly help if I broke down. The car was a bit upset to begin with but a tank of fresh fuel helped. We checked out a new coffee shop in time to notice a leaky thermostat housing. Pretty positive though and it wasn't doing any of the funky things before!
Yesterday I redid the thermostat seal. I took the thermostat neck and moved it over some sandpaper on a piece of glass (okay my coffee table) to make sure it was a nice flat surface. Then a good dose of the Right Stuff sealant and I refitted it. I've used this sealant in a few places on the car. It's excellent. Comes in a can with a trigger, sets in minutes and then the car is ready to go. It's a bit expensive here but absolutely worth it since it just works.
This morning I went to the Whocult meetup again in the C4. Made it there no problem and getting more confident with it I decided I'd take it up to Cheltenham this afternoon to meet with family for a meal. I felt like this would be a good test, if it can do that it's just going to be fine. Happily I got there and back just fine, making good progress and still getting 24mpg.
I've had the last couple of days to put a little over 250 miles on the car now and really get a feel for the new clutch setup. It's a riot! Compared to the factory dual mass there's a rattle at idle, but all the ZF6 boxes do this. First gear is nearly straight cut and the whine is much more pronounced now. Likewise with the poly engine & diff mounts (the drive train is only fixed to the chassis by these 4) all the vibration and noise is transmitted to you. It's much more racy and whilst the C6 is faster, smoother and “better” the C4 is a proper hooligan car. Being stuck behind people doing 40-50 I found myself changing gear more to be in a sweet spot and I wouldn't lug 6th at low speed anymore. However just chucking it through the gears with your own space it's a delight. The steering is only 2 turns lock to lock and with those big Michelin, Bilstein shocks and everything poly bushed it's like a V8 go cart.
The clutch replacement went okay to begin with. The old dual mass flywheel, which is unobtanium was well within spec so I sold it to a chap in Malta with a Callway twin turbo C4 to put on the shelf in case he needs it. The release bearing failed in a similar way to last time. So frustrating that a cheap part lets down the whole setup. You can't buy a quality one and even if you buy an expensive clutch/flywheel kit it still has the rubbish bearing.
The black tag German made ZF 6 box. This has different gear angles compared to the later blue tag USA made ones and was rated at 500ftlbs @ 50% capacity. Plenty of guys in the USA are putting double that through them!
Once it was fitted I drove the car around the yard and all seemed good. It went off to be MOT'd which it passed with flying colours and then I went to pick it up. Went to the petrol station obviously.
Then a few miles later the pedal went to the floor. One of the new hydraulic lines had split, inside the bell housing. My friend who fitted it turned up within about 30 minutes with a trailer to take it back. Much piss taking ensued as another friend going the other way spotted me and sent a photo to prove it. Then in work the next day a colleague who lives nearby came into work and said “you'll never guess who I saw yesterday on the A470?” to which everyone was in hysterics. A few days later it was back again with a better line made up.
I met up with some mates in Cardiff and we went for a little evening cruise down to the bay. Love the variety of old junk!
At Cowbridge cars & coffee I met up with another local C4 owner and then we both got out done when this turned up!
Then I went off to South America for a couple of weeks, which was fantastic. Had to lookout for Jaguars at the side of the road in Argentina, not the type with dodgy electrics either!
Then I got told off in Paraguay.
Back home the C4 had a niggly running issue, it was randomly cutting out but would then turn over really well with spark and fuel but not start for a bit. There didn't seem to be any pattern, hot, cold, under load, coasting etc. So I SORN'ed it.
I met up with Geraint also of PH with his MX5 although I was using the C6 a lot since it worked. Funny seeing the two cabrios together. I went to an American car meetup at Whocult doughnuts too and saw another C6 Z51 6 speed in Le Mans blue, apart from this one was a coupe. I'd seen it advertised before, it's a very nice car! Vesa also came to visit to have a go driving the C6. For an afternoon there was double trouble in my car port!
Dave (owner of Clive the Corvette) had asked me at the end of last year if I wanted to drive to the Sahara desert so I left the C4 behind once more. We had an incredible adventure and made it to the desert mostly drama free.
I helped out with the ubiquitous African detailing grit applicator.
Then I got told off again.
Back home again at the end of last month and with another week off coming up I thought I'd revisit the C4. I'm not sure if it's the demographic but there's still a busy forum that's good for advice. I thought I'd start with simple things first, I swapped the ECU for another reman one I'd bought before just because they're only about £80 and I thought it would be a useful for troubleshooting sometime. I swapped in my custom tune on the piggyback chip. The other thing I checked were the grounds on the bell housing These would have been disturbed during the clutch job. I managed to get another ½ turn on the bolt. It's funny working on it again, I've had it so long I don't need to look at any manuals and know what size the bolts are, if they're imperial or metric and so on. I'll have owned it 7 years next week! With that work done on Friday I taxed it! A friend came over in his Polo MK1 with a G40 1.3L supercharged swap to follow me to get some coffee and possibly help if I broke down. The car was a bit upset to begin with but a tank of fresh fuel helped. We checked out a new coffee shop in time to notice a leaky thermostat housing. Pretty positive though and it wasn't doing any of the funky things before!
Yesterday I redid the thermostat seal. I took the thermostat neck and moved it over some sandpaper on a piece of glass (okay my coffee table) to make sure it was a nice flat surface. Then a good dose of the Right Stuff sealant and I refitted it. I've used this sealant in a few places on the car. It's excellent. Comes in a can with a trigger, sets in minutes and then the car is ready to go. It's a bit expensive here but absolutely worth it since it just works.
This morning I went to the Whocult meetup again in the C4. Made it there no problem and getting more confident with it I decided I'd take it up to Cheltenham this afternoon to meet with family for a meal. I felt like this would be a good test, if it can do that it's just going to be fine. Happily I got there and back just fine, making good progress and still getting 24mpg.
I've had the last couple of days to put a little over 250 miles on the car now and really get a feel for the new clutch setup. It's a riot! Compared to the factory dual mass there's a rattle at idle, but all the ZF6 boxes do this. First gear is nearly straight cut and the whine is much more pronounced now. Likewise with the poly engine & diff mounts (the drive train is only fixed to the chassis by these 4) all the vibration and noise is transmitted to you. It's much more racy and whilst the C6 is faster, smoother and “better” the C4 is a proper hooligan car. Being stuck behind people doing 40-50 I found myself changing gear more to be in a sweet spot and I wouldn't lug 6th at low speed anymore. However just chucking it through the gears with your own space it's a delight. The steering is only 2 turns lock to lock and with those big Michelin, Bilstein shocks and everything poly bushed it's like a V8 go cart.
The C4 is epic!
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