6speed Turbo cars with 4.11's question
01-04-2011, 04:55 PM
#24
on hp logs the map reading is flat if i power shift which i very rarely do because i like my transmission. normally during a run the map reading dips by 20-30 kpa for one frame of hp tuners which is approx .2-.3 of a second and is immediately back at full boost. BOV never opens, pressure doesnt drop and the turbo stays spooled. i dont consider that losing boost but some might because of the small dip in map reading for the split second the throttle is closed
Last edited by Tally TransAm; 01-04-2011 at 05:01 PM.
01-05-2011, 09:37 PM
#26
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4.10's are very short of a gear for turbo cars. BUT, these other guys here are saying you won't see full boost with 4.10's is stupid. I saw 9 psi amost INSTANTLY no matter what gear I was in as long as I was under a load.
Here is a video my brother shot when he was down. Definetly pulls harder with 3.42's.
http://www.youtube.com/watch?v=c_YUtEcT510
Here is a video my brother shot when he was down. Definetly pulls harder with 3.42's.
http://www.youtube.com/watch?v=c_YUtEcT510
01-05-2011, 09:50 PM
#27
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First gear goes by in a flash with 4.11's, I really doubt you'd see full boost in 1st. Same with all the other gears too, the car goes through the gears so fast that you may spend more time shifting and less time actually building boost.
I'd swap back to 3.42's eventually, then you should have full boost even in 1st gear.
I'd swap back to 3.42's eventually, then you should have full boost even in 1st gear.
01-06-2011, 12:12 AM
#28
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4.10's are very short of a gear for turbo cars. BUT, these other guys here are saying you won't see full boost with 4.10's is stupid. I saw 9 psi amost INSTANTLY no matter what gear I was in as long as I was under a load.
Here is a video my brother shot when he was down. Definetly pulls harder with 3.42's.
http://www.youtube.com/watch?v=c_YUtEcT510
Here is a video my brother shot when he was down. Definetly pulls harder with 3.42's.
http://www.youtube.com/watch?v=c_YUtEcT510
01-06-2011, 12:07 PM
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Yep, it was just past 140 at the top of 4th. the 28" et streets are actually about 28.6" tall, and if you ever seen tires grow, they can be 30" or so. Not too high RPM, about 63-6400.
01-06-2011, 12:24 PM
#32
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I have a pretty light car (~2300) with 295/65 DRs. Car had a powerglide in is behind a stock 6.0. I'd like to go with a 76mm & ZO6 cam but I'm wondering if my 4.56s will be too much. The car liked more gear with the N/A SBC I had. It would run about a tenth.5 quicker with 4.70 gear with 29.5x10.5w over 4.70 with 31x13s. I'm wondering if it would be unmanageable with the 4.56 and boost on the 295s (about 30"). I hope the spread betweeen the 1.68 low and 1:1 high would be enough to make peak boost ESP. With a TB.
01-06-2011, 12:33 PM
#33
I have a pretty light car (~2300) with 295/65 DRs. Car had a powerglide in is behind a stock 6.0. I'd like to go with a 76mm & ZO6 cam but I'm wondering if my 4.56s will be too much. The car liked more gear with the N/A SBC I had. It would run about a tenth.5 quicker with 4.70 gear with 29.5x10.5w over 4.70 with 31x13s. I'm wondering if it would be unmanageable with the 4.56 and boost on the 295s (about 30"). I hope the spread betweeen the 1.68 low and 1:1 high would be enough to make peak boost ESP. With a TB.
But Id run a smaller gear for the boosted block, you dont want to run out of gear b4 the traps.
01-06-2011, 01:02 PM
#34
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I have a set of 60+" wheelie bars. I would like to be able to control boost and timing from launch. If I have too much rpm at the traps I could always use a GV overdrive. I really want to try the 4.56 with boost just to see for myself how it would be. Just gotta free up the funds for the parts I'm gonna need.
01-06-2011, 10:56 PM
#36
It basically applies to any car that has a lot of low end/midrange torque and high horsepower.
You just end up going through the gears more quickly than you need to be, wasting time shifting instead of accelerating.
It won't be as bad with a S/C, because you won't get any noticeable lag between shifts like you would with a turbo car. I'd still reccommend sticking with 3.42's though for a car making big power with a S/C or turbo.
01-22-2011, 01:16 PM
#38
The other thing to remember there too...as long as you don't seriously slow down the wheel in the turbo while you're shifting, the boost comes back much quicker than it does on initial spool.
Those wheels do have a decent amount of inertia, and they turn some serious RPM...so as long as you can shift quick without really being too abusive to the trans, a turbo stick car is a TON of fun to drive...and to me, there's nothing like putting it to the floor at 60mph in 4th or something, and feeling the car hit harder and harder as boost comes in.
Last edited by Mike454SS; 01-22-2011 at 01:24 PM.
03-14-2011, 11:52 AM
#39
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The 20-30 KPA loss he mentioned is ~2.9-4.3 psi loss during a shift.
The other thing to remember there too...as long as you don't seriously slow down the wheel in the turbo while you're shifting, the boost comes back much quicker than it does on initial spool.
Those wheels do have a decent amount of inertia, and they turn some serious RPM...so as long as you can shift quick without really being too abusive to the trans, a turbo stick car is a TON of fun to drive...and to me, there's nothing like putting it to the floor at 60mph in 4th or something, and feeling the car hit harder and harder as boost comes in.
The other thing to remember there too...as long as you don't seriously slow down the wheel in the turbo while you're shifting, the boost comes back much quicker than it does on initial spool.
Those wheels do have a decent amount of inertia, and they turn some serious RPM...so as long as you can shift quick without really being too abusive to the trans, a turbo stick car is a TON of fun to drive...and to me, there's nothing like putting it to the floor at 60mph in 4th or something, and feeling the car hit harder and harder as boost comes in.
