4T80E/Turbo-S/C... TIME FOR A NEW THREAD? - Page 39 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

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Old 12-31-2007, 06:10 PM   #381
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Quote:
Originally Posted by 2000SilverBullet
No but I'll bet it'* a 12 sec car for sure.
And that'* just on 16psi. Once I go for full boost (20+) It shoudl REALLY get fun! Now that I know the FDR is a 4.00, it looks like 2nd gear starts and a 3-4 shift will be req'd in the 1/4-mile. 1st gear will only run 40mph and probably be nothing but wheel spin.
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Old 12-31-2007, 06:15 PM   #382
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Are you concerned at all about Boost stacking

I though our PCM'* and MAP sensors only detect up to 15 psi

I would launch in 1st gear and improve your traction. Thought much about wheelie bars to move more weight distribution forward
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Old 12-31-2007, 06:30 PM   #383
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Quote:
Originally Posted by 2000SilverBullet
Are you concerned at all about Boost stacking
Boost stacking is something I only ever heard of on */c engines. Turbos don;t boost stack b/c the wg controls boost output and limits it to whatever desired max boost I choose. If the engine will ingest 21psi, no problem. The engine will injest 40psi if I want to squeeze it that much. On a */c engine, you see boost stack b/c the blower speed is linear, whereas the VE of the engine is not. As VE goes down at high rpms, boost in the manifold goes up. WHen this happens on a turbo app, the w.g opens and slows the turbine so you don;t get the "stacking" up in the manifold. Since ultimately, this engine is turbo fed, I won't have boost stack.

Quote:
Originally Posted by 2000SilverBullet
I though our PCM'* and MAP sensors only detect up to 15 psi.
The MAP is 15psi, but it has little to do with fueling, it'* only a reference. The MAF fuels the engine when it is plugged in and working properly. If the MAF drops out due to malf or unplugging, the pcm falls back into speed-density mode and uses MAP and RPM to fuel the engine. If both MAF and MAP are lost, then there is Alpha-N (limp) mode which is a linear TPS vs. RPM mode of fueling.

Quote:
Originally Posted by 2000SilverBullet
I would launch in 1st gear and improve your traction. Thought much about wheelie bars to move more weight distribution forward
I don;t have 1st gear control yet, still waiting to sort out the whole TCM thing. While I wait for the time, I have the trans in full manual mode. Once I start racing it, I will make sure the rear strut airbags are good and hook up the compressor to a toggle switch so I can pump them up to 100psi. That'* all I'll do, it worked on my turbo GA putting airshocks on the back of it. It really made the car easy to drive, got rid of bump-torque-steer under full boost which makes the car drive left-right-left-right enough to scatre the hell out of you at 100+mph! Once I put the air shocks on the GA< it went straight as an arrow and ran 115mph in the 1/4-mile! (at a severely traction limited and clutch slipping 13.96 :(
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Old 01-01-2008, 07:11 PM   #384
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Excellent response Jeff.
That clears up a few misconceptions I had. I've done some more research based on your explainations and now am clear.
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Old 01-02-2008, 12:50 PM   #385
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Quote:
Originally Posted by 2000SilverBullet
Excellent response Jeff.
That clears up a few misconceptions I had. I've done some more research based on your explainations and now am clear.
Thanks! I'm glad I could help you understand it. There are alot of common misconceptions being spread by people who read more than they know about cars. And then they talk like they know more than they do! That keeps people like you from knowing the truth and people like them looking smarter than they are!

Talk about confusion! LOL! That was confusing!

I think you get my point, though...
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Old 01-02-2008, 11:13 PM   #386
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Well, having a little fun in the 21deg temps tonight, i guess I "leaned" on it a little too hard (pun intended) and popped the hg out right under the #4 plug.

FU-U-U-U-U-U-U-U-U-U-U-U-U-U-U-U-U-U-U-U..........

I hope it din hurt the piston/rings. I had to limp back tothe shop about 3 miles. Oh, I was on it purty hard, WOT, it popped about 4000rpm (peak VE, peak cyl pressure, peak tq) I just the other day thought about skewing the rear bank due to the header on the back... at 12.5 a/f, the front is probably 11.5 and the rear 13.5... and with the cold temps, it might have seen more than 16psi.......

No time this week, I'll be driving the truck I guess.
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Old 01-02-2008, 11:17 PM   #387
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ohhh mannn, what a bummer. you have to take it apart again! that suxxx.

you can probably tear that down to a short block, blind-folded by now huh?

keep up posted
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Old 01-02-2008, 11:25 PM   #388
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I have much respect for anyone who can keep their cool and not get overly frusterated with all this. As much as I like working on cars, I just get worn out with all the twisting and finger hurting and bruises that my engine gave me doing my LIM Gasket the past two days.

Props to anyone, especially you; to take the chance, to troubleshoot, to take apart, to put back together, to take apart, put back together, etc. and still not give up.
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Old 01-02-2008, 11:56 PM   #389
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Quote:
popped the hg out right under the #4 plug.
What does that mean
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Old 01-03-2008, 12:00 AM   #390
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blew a head gasket from all the boost
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