Is a VB upgrade and regular 3.26 gearing a MUST for a supercharged GS4?
10-06-10, 09:35 AM
#1
Is a VB upgrade and regular 3.26 gearing a MUST for a supercharged GS4?
Is a VB upgrade and regular 3.26 gearing a MUST for a supercharged GS4? I need to know this ASAP.
I like my 3.76 LSD diff
and
I DO NOT like the "side effects" of a valve body upgrade
Yeah, the VB upgrade makes shifts fast, tight and smooth at WOT but I've read in MANY places (and spoke to Mo from Swift Racing Tech) that it really BANGS from gear to gear for normal driving; not cool and would be rather annoying in a daily driver car.
Someone please chime in with some experience!
Thanks,
Nick
I like my 3.76 LSD diff
and
I DO NOT like the "side effects" of a valve body upgrade
Yeah, the VB upgrade makes shifts fast, tight and smooth at WOT but I've read in MANY places (and spoke to Mo from Swift Racing Tech) that it really BANGS from gear to gear for normal driving; not cool and would be rather annoying in a daily driver car.
Someone please chime in with some experience!
Thanks,
Nick
10-07-10, 09:11 AM
#2
Lexus Champion
I haven't really dug into what is possible for these cars as the transmission is too weak to handle too much torque regardless of valve body modifications.
Seems like the biggest problem is the tranny not shifting before it hits the rev limiter. Not good. It is frustrating that there is no way to reprogram the transmission for quick aggressive shifts under full throttle but normal shifts otherwise. It would also be nice to reprogram it to always shift at 6200rpm (it does sometimes but not always) on stock or NA cars and maybe slightly lower for turbo/supercharged/nitrous use. OR... raise the engines rev limiter.
With stronger rods these engines would have no problem reving to 7000rpm. A first generation 1uzfe from a Tokyo taxi with proper headers and no intake manifold restriction made 306hp @ 6500rpm and 270tq @ 5000rpm on the stock factory cams and untouched stock intake ports, intake valves, exhaust ports and exhaust valves. This was an engine that was rated 250hp at 5600rpm and 260tq at 4400rpm and made more like 235hp as installed. The VVTi engines have MUCH MUCH better flowing stock heads, MUCH MUCH better flowing intake manifolds, bigger valves, better cam timing and should make peak power no lower than the taxi motors 6500rpm and probably higher. Ours are rated 300hp at 6000rpm. Of course we CAN'T rev past the factory fuel cut at 6350rpm and our rods are not as strong as that taxi motor.
All the above said there is no reason that our transmissions could not be programmed to do what I mentioned other than the factory ECUs for the engine and transmission have not been hacked.
I propose someone with the electronic know-how could create an intercepting device to capture engine RPM signalling before it reaches the stock ECU. It would simply pass the signal on until 6300rpm is reached and then continue sending 6300rpm as the engine revs higher and then at whatever preset number would then signal 6350rpm sending the ECU into factory fuel cut rev limit. Maybe the right person will read this and get this ball rolling. This would solve the problem of fuel cut with the stock transmission since that is happening because the tranny does not shift quickly enough and raising the rev limit a couple hundred RPM would allow it time. Higher than stock gearing and lighter torque converters such as the Precision Industries allow the engine to rev more quickly making the stock shifting problem worse but would be fixed with raising the rev limit.
Seems like the biggest problem is the tranny not shifting before it hits the rev limiter. Not good. It is frustrating that there is no way to reprogram the transmission for quick aggressive shifts under full throttle but normal shifts otherwise. It would also be nice to reprogram it to always shift at 6200rpm (it does sometimes but not always) on stock or NA cars and maybe slightly lower for turbo/supercharged/nitrous use. OR... raise the engines rev limiter.
With stronger rods these engines would have no problem reving to 7000rpm. A first generation 1uzfe from a Tokyo taxi with proper headers and no intake manifold restriction made 306hp @ 6500rpm and 270tq @ 5000rpm on the stock factory cams and untouched stock intake ports, intake valves, exhaust ports and exhaust valves. This was an engine that was rated 250hp at 5600rpm and 260tq at 4400rpm and made more like 235hp as installed. The VVTi engines have MUCH MUCH better flowing stock heads, MUCH MUCH better flowing intake manifolds, bigger valves, better cam timing and should make peak power no lower than the taxi motors 6500rpm and probably higher. Ours are rated 300hp at 6000rpm. Of course we CAN'T rev past the factory fuel cut at 6350rpm and our rods are not as strong as that taxi motor.
All the above said there is no reason that our transmissions could not be programmed to do what I mentioned other than the factory ECUs for the engine and transmission have not been hacked.
I propose someone with the electronic know-how could create an intercepting device to capture engine RPM signalling before it reaches the stock ECU. It would simply pass the signal on until 6300rpm is reached and then continue sending 6300rpm as the engine revs higher and then at whatever preset number would then signal 6350rpm sending the ECU into factory fuel cut rev limit. Maybe the right person will read this and get this ball rolling. This would solve the problem of fuel cut with the stock transmission since that is happening because the tranny does not shift quickly enough and raising the rev limit a couple hundred RPM would allow it time. Higher than stock gearing and lighter torque converters such as the Precision Industries allow the engine to rev more quickly making the stock shifting problem worse but would be fixed with raising the rev limit.
10-07-10, 10:18 AM
#3
The shame about of all this is I was literally JUST about to pull the trigger on an SC kit (you'll see it in the classifieds soon from the member) but this is the only reason why I am backing out. Since this car is my daily driver and will be for the next 2 yrs or so I cannot live with a horibbly shifting transmission around town when I am driving normally...not for NY and especially not when our winters come. Damn our trannys to hell!
10-07-10, 12:44 PM
#4
Honestly I didn't think it felt horrible at all. Granted my VB did not affect the 1-2 shift, I got used to it quick. Heck I was driving my grandma around in my car. When you get to the point of modifying your car to that level, you have to give up comfort and stock driveability to some degree. Its up to each individual though if the the benefits of SC are worth giving up stock driveability. Good luck either way 
Last edited by mex lex; 10-07-10 at 12:56 PM.
10-07-10, 01:05 PM
#5
I haven't really dug into what is possible for these cars as the transmission is too weak to handle too much torque regardless of valve body modifications.
Seems like the biggest problem is the tranny not shifting before it hits the rev limiter. Not good. It is frustrating that there is no way to reprogram the transmission for quick aggressive shifts under full throttle but normal shifts otherwise. It would also be nice to reprogram it to always shift at 6200rpm (it does sometimes but not always) on stock or NA cars and maybe slightly lower for turbo/supercharged/nitrous use. OR... raise the engines rev limiter.
With stronger rods these engines would have no problem reving to 7000rpm. A first generation 1uzfe from a Tokyo taxi with proper headers and no intake manifold restriction made 306hp @ 6500rpm and 270tq @ 5000rpm on the stock factory cams and untouched stock intake ports, intake valves, exhaust ports and exhaust valves. This was an engine that was rated 250hp at 5600rpm and 260tq at 4400rpm and made more like 235hp as installed. The VVTi engines have MUCH MUCH better flowing stock heads, MUCH MUCH better flowing intake manifolds, bigger valves, better cam timing and should make peak power no lower than the taxi motors 6500rpm and probably higher. Ours are rated 300hp at 6000rpm. Of course we CAN'T rev past the factory fuel cut at 6350rpm and our rods are not as strong as that taxi motor.
All the above said there is no reason that our transmissions could not be programmed to do what I mentioned other than the factory ECUs for the engine and transmission have not been hacked.
I propose someone with the electronic know-how could create an intercepting device to capture engine RPM signalling before it reaches the stock ECU. It would simply pass the signal on until 6300rpm is reached and then continue sending 6300rpm as the engine revs higher and then at whatever preset number would then signal 6350rpm sending the ECU into factory fuel cut rev limit. Maybe the right person will read this and get this ball rolling. This would solve the problem of fuel cut with the stock transmission since that is happening because the tranny does not shift quickly enough and raising the rev limit a couple hundred RPM would allow it time. Higher than stock gearing and lighter torque converters such as the Precision Industries allow the engine to rev more quickly making the stock shifting problem worse but would be fixed with raising the rev limit.
Seems like the biggest problem is the tranny not shifting before it hits the rev limiter. Not good. It is frustrating that there is no way to reprogram the transmission for quick aggressive shifts under full throttle but normal shifts otherwise. It would also be nice to reprogram it to always shift at 6200rpm (it does sometimes but not always) on stock or NA cars and maybe slightly lower for turbo/supercharged/nitrous use. OR... raise the engines rev limiter.
With stronger rods these engines would have no problem reving to 7000rpm. A first generation 1uzfe from a Tokyo taxi with proper headers and no intake manifold restriction made 306hp @ 6500rpm and 270tq @ 5000rpm on the stock factory cams and untouched stock intake ports, intake valves, exhaust ports and exhaust valves. This was an engine that was rated 250hp at 5600rpm and 260tq at 4400rpm and made more like 235hp as installed. The VVTi engines have MUCH MUCH better flowing stock heads, MUCH MUCH better flowing intake manifolds, bigger valves, better cam timing and should make peak power no lower than the taxi motors 6500rpm and probably higher. Ours are rated 300hp at 6000rpm. Of course we CAN'T rev past the factory fuel cut at 6350rpm and our rods are not as strong as that taxi motor.
All the above said there is no reason that our transmissions could not be programmed to do what I mentioned other than the factory ECUs for the engine and transmission have not been hacked.
I propose someone with the electronic know-how could create an intercepting device to capture engine RPM signalling before it reaches the stock ECU. It would simply pass the signal on until 6300rpm is reached and then continue sending 6300rpm as the engine revs higher and then at whatever preset number would then signal 6350rpm sending the ECU into factory fuel cut rev limit. Maybe the right person will read this and get this ball rolling. This would solve the problem of fuel cut with the stock transmission since that is happening because the tranny does not shift quickly enough and raising the rev limit a couple hundred RPM would allow it time. Higher than stock gearing and lighter torque converters such as the Precision Industries allow the engine to rev more quickly making the stock shifting problem worse but would be fixed with raising the rev limit.
Also if you are willing to do a piggy back like a Greddy EMU, one of its fetures is the ability to raise the rev limiter. IS300 guys seem to have success with this because they can raise it to 7000rpm and gain another 10-15 hp on NA applications if I remember correctly.
And thanks for the info on the Tokyo taxi 1UZ. I think too many V8 owners underestimate the potential of these motors with bolt ons.
Last edited by mex lex; 10-07-10 at 01:10 PM.
10-10-10, 07:23 AM
#6
The shame about of all this is I was literally JUST about to pull the trigger on an SC kit (you'll see it in the classifieds soon from the member) but this is the only reason why I am backing out. Since this car is my daily driver and will be for the next 2 yrs or so I cannot live with a horibbly shifting transmission around town when I am driving normally...not for NY and especially not when our winters come. Damn our trannys to hell!
I drove Mr Johnson's car and the only issue it had was hitting the rev limiter. The shifts were fine IMO and just fine for a daily driver. If you have an option to get a used kit I would be all over it. I just picked up some stuff my self and Im going to attempt this one more time to see if I can make this work
10-12-10, 02:15 PM
#7
I have had no issues with my VB upgrade which was smooth and crisp before and after I had the SC installed which has been for about 4 years now. If there is a legitimate concern by others of hard shifting I can only speculate that "their" VB upgrade was a more aggressive upgrade version that shifted harder.
I think you should search for VB upgrade threads as I don't ever recall anyone complaining of hard shifts.
I think you should search for VB upgrade threads as I don't ever recall anyone complaining of hard shifts.
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10-12-10, 02:21 PM
#8
I have had no issues with my VB upgrade which was smooth and crisp before and after I had the SC installed which has been for about 4 years now. If there is a legitimate concern by others of hard shifting I can only speculate that "their" VB upgrade was a more aggressive upgrade version that shifted harder.
I think you should search for VB upgrade threads as I don't ever recall anyone complaining of hard shifts.
I think you should search for VB upgrade threads as I don't ever recall anyone complaining of hard shifts.
