Car won't launch!!!

702 Views 9 Replies 9 Participants Last post by chazcross, Jun 10, 2005

turbo2z

Discussion Starter · May 14, 2005

Having a hard time figuring out why the car won't launch with the new auto and larger turbo. Here's the deal.
New trans with semi low stall 2800RPM
big hybrid turbo only pulling 6psi at 2800 torque braking. Engine RPM will slowly climb when brake release and slowly build boost. Once it get's past say 3500 it's a rocket 25psi tires spinning but it launches like a 2.0 Neon would. The car is getting dynoed this weekend to get the bugs worked out but this is bothering me. It's almost like it needs a higher stall or a trans brake or something. Timing is dead nuts. On the street from a roll it will shread 1st and second gear and start to spin in 2rd at 25psi. From a dead stop a bicycle would be faster.
Any ideas. We are planning on going to the track in 2 weeks after the intercooler piping and cage are installed.
This one has me stumped.

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TylerEss

· #2 · May 14, 2005

I'm not a big launch expert or anything, but I'd bet that it's the fact that you're leaving the line at 6psi. Personally, I don't mind leaving the line at 6psi IN MY STOCK T1 LOG CAR.:thumb:
I think a lot of the guys run a HIGHER stall convertor to get the exhaust flow up and spin the turbo up faster. Why'd you pick a lower stall unit?

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Moparbishi

· #3 · May 15, 2005

low stall speed. turbo hasnt spool enough yet. get a 2 stage and up your launch boost or your stall speed.

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glhsken

· #4 · May 15, 2005

3.0 acclaim said:
low stall speed. turbo hasnt spool enough yet. get a 2 stage and up your launch boost or your stall speed.

+1.. Stall is way too low for a hybrid. you need 3500 or so stall

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Ondonti

· #5 · May 15, 2005

2.2 with 6psi on launch..............I cant say that would be exciting at all..............more like pathetic if you are hitting 25 psi a few rpm later.

get a higher stall converter. you arent making those magical gobs of lowend torque with your setup.

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turbo2z

Discussion Starter · #6 · Jun 7, 2005

Thanks for all of those that responded. The convertor came with the trans so we just bolted it in. I am looking into a 3500 stall convertor right now so we shall see.

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2.2=8

· #7 · Jun 7, 2005

What is your final drive ratio? You either need to launch at 3500rpm or higher, or achieve at least 12psi on launch, or preferably both. I have found leaving with the auto to be every bit as tricky as a manual but once you find the right technique it is fun

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kedavis

· #8 · Jun 7, 2005

I agree stall speed is to low I have my stage limiter set at 3750.

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thatsbc

· #9 · Jun 9, 2005

Hmm

I had a problem like this once, turned out to be that the cam timing was off.

Once we fixed it, it ran great, didn't change anything else.

bc

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chazcross

· #10 · Jun 10, 2005

turbo2z said:
Engine RPM will slowly climb when brake release and slowly build boost. Once it get's past say 3500 it's a rocket 25psi tires spinning but it launches like a 2.0 Neon would.

My car does the same thing, Ill check my timing this weekend.

thatsbc:
How off was your timing?

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