VXR8 and the autobox
Discussion
I have to make a decision, which torque converter to buy, I'm only just beginning to understand this stall speed business, so if anyone has any advice it would be very welcome.
Is the VXR8 diff 2.9 ratio? Would it be a better idea getting the higher stall speed converter (3600) and a new 3.7 ratio diff? Or stick with the standard diff and maybe 3200 or 3400 stall speed? How is this going to effect the gearing and overall driving or the car?
Cheers guys any help is greatly appreciated.
Is the VXR8 diff 2.9 ratio? Would it be a better idea getting the higher stall speed converter (3600) and a new 3.7 ratio diff? Or stick with the standard diff and maybe 3200 or 3400 stall speed? How is this going to effect the gearing and overall driving or the car?
Cheers guys any help is greatly appreciated.
Gareth knows a bit about them. My understanding is that you will get way more slip with those stall speeds, though the TC in the late model Auto's can electronically lock up. I would have through 3900 is too high. Most guys go high 2000 range or low 3000 in a daily driver IIRC.
Around town you will eat more fuel due to extra slip, but the TC will start to "stall" at a higher than stock speed, in effect launching at a higher torque output like a manual with a clutch. You can tune the trans to lock at different points, so the tune should match the stall IMO.
Id do some reading on ls1.com.au see what the guys there use. I think Ive seen 3200 quite frequently.
Do you have trouble breaking traction now mate? You might be better off with a diff ratio change. Maybe a 3.7 from a manual, or a 3.45 from an SS or somenthing etc, that with the low 1st in the auto should be pretty mental wihtout the additional slip.
Around town you will eat more fuel due to extra slip, but the TC will start to "stall" at a higher than stock speed, in effect launching at a higher torque output like a manual with a clutch. You can tune the trans to lock at different points, so the tune should match the stall IMO.
Id do some reading on ls1.com.au see what the guys there use. I think Ive seen 3200 quite frequently.
Do you have trouble breaking traction now mate? You might be better off with a diff ratio change. Maybe a 3.7 from a manual, or a 3.45 from an SS or somenthing etc, that with the low 1st in the auto should be pretty mental wihtout the additional slip.
I'm a fan of automatics and only have a manual Monaro because had no choice. In my view muscle cars should be auto as most US ones were. I love the way with our 4.6GT Mustang you floor both pedals and the wheels spin with the car stationary. Can't do that in the Monaro.
My old granny with a carb 2.8 V6 stalled at 2000 rpm which I thought was well matched to this flexible engine.
My 72 Mustang had a 3000rpm converter which I thought was too high. I changed it to 2500 rpm and changed the diff from 3.25 to 3.5 as the same time. So shortening the diff compensated for the reduced torque converter multiplication.
I would have thought 2500rpm was about right for an LS2. With the lock up and 6 speeds its characteristics will play a much smaller part in the driving experience compared to a 3 speed of yester year. What is the current one, why would you want to change it?
One problem with high stall converters for street use is that the engine note ends up being boringly constant. Can't play the tunes you can with a manual.
My old granny with a carb 2.8 V6 stalled at 2000 rpm which I thought was well matched to this flexible engine.
My 72 Mustang had a 3000rpm converter which I thought was too high. I changed it to 2500 rpm and changed the diff from 3.25 to 3.5 as the same time. So shortening the diff compensated for the reduced torque converter multiplication.
I would have thought 2500rpm was about right for an LS2. With the lock up and 6 speeds its characteristics will play a much smaller part in the driving experience compared to a 3 speed of yester year. What is the current one, why would you want to change it?
One problem with high stall converters for street use is that the engine note ends up being boringly constant. Can't play the tunes you can with a manual.
Cheers for the input guys, Rich I've been over on ls1tech, ls1.com.au and the g8 forums, way too much info to take in.
I still can't find out for certain what diff ratio I have, either it's 2.92 or 3.25? The torque converter builder wants to know so he can match up the converter and tune. Then I threw in the option of changing the diff too.
I would like the car to have slightly longer gearing, 1st is too short and 2nd could do with hanging in there some more too, shouldn't effect 1/4 mile times as it'll still be in 4th over the line.
I still can't find out for certain what diff ratio I have, either it's 2.92 or 3.25? The torque converter builder wants to know so he can match up the converter and tune. Then I threw in the option of changing the diff too.
I would like the car to have slightly longer gearing, 1st is too short and 2nd could do with hanging in there some more too, shouldn't effect 1/4 mile times as it'll still be in 4th over the line.
The diff ratio should be attached to a little tag somewhere on the diff, so you need to get in in the air and have a look.
Unless another expert can elighten us further, my understanding is that the stall would need to be matched to the revs at which maximum torque is produced for the greatest effect, so you would need a dyno map to find out where that is. Also bear in mind that any future engine mods which alter the power and torque bands will affect the stall. This is why some manufacturers will allow you one stall change when you buy their unit.
Ringram is quite right in that high stalls are really track specific and can be "loose" to drive around town at low speeds. Most modern stalls have electronic lock up but you need to make sure.
There's nothing you can do about the ratios' in the box, and with six of them in yours, they are going to be shorter, but you can alter the gearbox tune to help out.
Unless another expert can elighten us further, my understanding is that the stall would need to be matched to the revs at which maximum torque is produced for the greatest effect, so you would need a dyno map to find out where that is. Also bear in mind that any future engine mods which alter the power and torque bands will affect the stall. This is why some manufacturers will allow you one stall change when you buy their unit.
Ringram is quite right in that high stalls are really track specific and can be "loose" to drive around town at low speeds. Most modern stalls have electronic lock up but you need to make sure.
There's nothing you can do about the ratios' in the box, and with six of them in yours, they are going to be shorter, but you can alter the gearbox tune to help out.
I think your drive ratio is 3.27
http://www.carsales.com.au/news/2006/large-passeng...
Probably 2.92 in standard Calais and SS form.
Lockup converter would help, but makes the tune more intesting. I think 1st is 4:1 in the auto, so it is very low.
http://www.carsales.com.au/news/2006/large-passeng...
Probably 2.92 in standard Calais and SS form.
Lockup converter would help, but makes the tune more intesting. I think 1st is 4:1 in the auto, so it is very low.
Diff on CLubsport R8 (VXR8) is 'HSV specific' - 3.7 manual, 3.27 auto
www.hsv.com.au/cars/ESeries/clubsportr8/specs.asp
www.hsv.com.au/cars/ESeries/clubsportr8/specs.asp
mystvxr...why are you putting a higher stall in, what are you trying to achieve as the end result?
and what other mods has the vehicle had to date.....these are all factors that need to be addressed before a stall (if any is selected). with these new gen box's the trans map is just as important than the stall speed.
and what other mods has the vehicle had to date.....these are all factors that need to be addressed before a stall (if any is selected). with these new gen box's the trans map is just as important than the stall speed.
Mystvxr said:
Cheers for the input guys, Rich I've been over on ls1tech, ls1.com.au and the g8 forums, way too much info to take in.
I still can't find out for certain what diff ratio I have, either it's 2.92 or 3.25? The torque converter builder wants to know so he can match up the converter and tune. Then I threw in the option of changing the diff too.
I would like the car to have slightly longer gearing, 1st is too short and 2nd could do with hanging in there some more too, shouldn't effect 1/4 mile times as it'll still be in 4th over the line.
I still can't find out for certain what diff ratio I have, either it's 2.92 or 3.25? The torque converter builder wants to know so he can match up the converter and tune. Then I threw in the option of changing the diff too.
I would like the car to have slightly longer gearing, 1st is too short and 2nd could do with hanging in there some more too, shouldn't effect 1/4 mile times as it'll still be in 4th over the line.
Id suggest you have a 3.27:1 diff. Thats what the HSV website says. Id be inclined to use a stock convertor, unless you are building a drag car. Anything much "looser" will drive you mad and drink fuel - imo!
TTLS1: Car is supercharged and should be making 550+ at the flywheel but that doesn't seem to be transferring very well through the gearbox, my aim is to uprate in any way possible the autobox and drivetrain's ability to cope with the current power and any more that may be added in the future!
I would happily buy an off the shelf fully rebuilt box but it seems I'll have to source parts and have this done for me here in the UK.
The converter builder and tuner will supply a tune and seem to think a 3600 stall would work well and suggest I could even fit the 2.92 diff to have the slightly longer gearing I am looking for.
That said, I value the opinions here and am more likely to trust your opinions than a tuner trying to sell me their parts, so I might leave this alone and just look at the gearbox internals and TCM tune for now.
Thanks all for your help.
I would happily buy an off the shelf fully rebuilt box but it seems I'll have to source parts and have this done for me here in the UK.
The converter builder and tuner will supply a tune and seem to think a 3600 stall would work well and suggest I could even fit the 2.92 diff to have the slightly longer gearing I am looking for.
That said, I value the opinions here and am more likely to trust your opinions than a tuner trying to sell me their parts, so I might leave this alone and just look at the gearbox internals and TCM tune for now.
Thanks all for your help.
3600 sounds very high for the road. Even going gently it will be slipping 2500 - 3000. Not sure what the engine management will make of it. Perhaps that is the trouble, it is confused and changing up to early?
With the SC even low to midrange torque will be increased so will increase the stock converter stall speed slightly.
I meant to test drive an auto VXR8 last year but never got round to it.
With the SC even low to midrange torque will be increased so will increase the stock converter stall speed slightly.
I meant to test drive an auto VXR8 last year but never got round to it.
it makes a little more sense now I know it's SCharged. But I tend to agree that 3600 sounds a little high for a predominantly street vehicle. I wouldn't let the fear of a hi stall being too 'loose' scare you mate, I was running a 4k fuddle in the last combo and it felt as tight as a stockko. It won't slip and flash all over the place unless it's a very poorly built one and your tune is all wrong.If done correctly it will only flash hard at WOT.
Hi-stalls are representative of the rpm range of your combo, if you have a head and cam combo that produces bulk torque between 4500-6500 then you'd be better served with a hi-stall in the 5500 range. If you're still running standard cam & heads and only the SC I'b be inclined to think you start producing builk torque from around 3000rpm? (if you have a dyno sheet it'd be helpfull in stall selection)if this is the case i'd lean towards a 3200 Yank or Fuddle, you won't have a massive rev-rang so don't waste it all on stall. But it will allow you to leave the line harder without too much stress on the box and drive-line.
As far as changing your diff ratio...don't do it, it'll feel like draging a boat anchor and if you're ever going to take her to the Pod etc, your 60' times won't be exciting and you'll kick yourself. If this is more of a V-max top end speed thing your chasing sure go to the 2.9's but then you won't need the stall as it won't be beneficial in reaching this goal...oh and be prepared to left at the lights by a diesel passats and reps in Mondeos.
Hope this is of some help......another opinion but forums are full of them
Hi-stalls are representative of the rpm range of your combo, if you have a head and cam combo that produces bulk torque between 4500-6500 then you'd be better served with a hi-stall in the 5500 range. If you're still running standard cam & heads and only the SC I'b be inclined to think you start producing builk torque from around 3000rpm? (if you have a dyno sheet it'd be helpfull in stall selection)if this is the case i'd lean towards a 3200 Yank or Fuddle, you won't have a massive rev-rang so don't waste it all on stall. But it will allow you to leave the line harder without too much stress on the box and drive-line.
As far as changing your diff ratio...don't do it, it'll feel like draging a boat anchor and if you're ever going to take her to the Pod etc, your 60' times won't be exciting and you'll kick yourself. If this is more of a V-max top end speed thing your chasing sure go to the 2.9's but then you won't need the stall as it won't be beneficial in reaching this goal...oh and be prepared to left at the lights by a diesel passats and reps in Mondeos.
Hope this is of some help......another opinion but forums are full of them
TTLS is pretty much spot on. Convertor choice is really a function of how your motor delivers the goodies, driveline combo (diff ratio, tyre size) and how you plan to spend most of your driving time with it. Drag cars choose high stall rates generally around peak torque to give the hardest, quickest (usually front wheels in the sky) launches and therefore best quarter time. Makes them pretty fluffy to drive at part throttle tho! If this car is mostly a street driver, think about where your tacho needle spends the majority of it's time... around 2500rpm?
Also as he's already said, look at the gearbox itself and it's shifting behavior. Most factory boxes have very quick upshifts and almost seem to skip intermediate gears at part throttle, as they are designed to try and get you into top gear as quickly as possible so as to deliver the best economy they can and to make use of the large amount of torque multiplication possible to waft you along. If you're trying to make it more like a manual car and hold the gears more, you'll need to re-jig it somehow. But also remember that the multi-gear modern boxes are not as strong when it comes to poking them with big power and torque. There is good reason that the 2-speed Powerglide is the transmission of choice in the drag racing world, and that is because 2 gears means more space to make the actual gears and clutches bigger and components therefore stronger... Also less shifts mean more time spent with engine output going to the wheels, and if you have a fit motor then you have no use for multiple gearings
Also as he's already said, look at the gearbox itself and it's shifting behavior. Most factory boxes have very quick upshifts and almost seem to skip intermediate gears at part throttle, as they are designed to try and get you into top gear as quickly as possible so as to deliver the best economy they can and to make use of the large amount of torque multiplication possible to waft you along. If you're trying to make it more like a manual car and hold the gears more, you'll need to re-jig it somehow. But also remember that the multi-gear modern boxes are not as strong when it comes to poking them with big power and torque. There is good reason that the 2-speed Powerglide is the transmission of choice in the drag racing world, and that is because 2 gears means more space to make the actual gears and clutches bigger and components therefore stronger... Also less shifts mean more time spent with engine output going to the wheels, and if you have a fit motor then you have no use for multiple gearings
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