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Twin engine GTP project progress thread



Nice progress man, been following this for awhile and glad to see it on the road. Let's see a video or 2 of surprising unsuspecting drivers of the monster you have there.

Nice job
 
98GrandPrixIraqVet said:
For the love of god I cannot wait to see track vids!
Click to expand...
Thanks... what's amazing about this car is that it's actually quicker on the street.
Unlike 95% of the cars out there. it actually loves a little wheelspin to help the 60 foot.
I didn't tell you guys but the data I have is 9 sec material on the street.

At the strip the glue + 2nd gear start made it slower off the line.
But still made a 1.65 60 foot (instead of 1.5) and ran
10.0 twice @ 141 mph ! Not bad

Amazing 110 mph trap speed in the 1/8 mile in only 6.5 seconds !!
0-60mph of 2.4 seconds

Then I went for a real run and ran more boost off the line to get a solid 60 foot on the glue + a 9 sec pass that the car can do.
And broke the input shaft of the rear trans. It hooks too hard for the stock input shaft.

 
91parkave said:
congrats man youve reached god status now. whats next? twin sequential trans
Click to expand...
lol...

This is just the beginning for that car. Everything worked out so well, better even than I imagined.

Now we can lighten up the car, there is still an easy 200 lbs to remove and we will be looking into a built rear trans. 1st gear start for the rear engine.
Full slicks on all four. high boost on both engines.
New turbos front and back ( They both have strong points) but the new turbo will be good everything. Quick spool, big power etc...

But it will take a few weeks to see it back at the strip but I'm shooting low 9s or high 8s as a goal for the end of the year.

btw I was shocked that car only weighs 4350lbs with me in it. I was sure it was 4500-4800lbs
 


darkhorizon said:
how low is low boost, what turbos front and rear?
Click to expand...
GTX3076 up front. 6262 precision in the back

14-15 psi on both on the street which netted me a better 660 feet ET due to a better launch
At the strip with the glue I felt I needed more boost.

So front engine is the same. I start 10 psi then ramp up to 15 psi. Rear engine 22 psi from the start.
On my other cars I ran up to 29 psi. Of course gains are not huge from 20 psi to 29 psi because of the trans slipping.
So I would expect stock trans if it would hold up 3-4 tenths quicker at full boost on both engine.

But I think the biggest gain will be 1st gear starts and built trans that actually put down the full power when I raise the boost.
 
Best project ever and hold on to those turbos and anything else you discard. I want to do a basic turbo build on a Spring/Summer/Fall Daily driver Prix.
 
I think the best turbos for my application would be two 5558 Precision turbo. Instant spool and decent max power.
However once I start getting high 8s/low 9s they will hold me back.

If I go with another 6262 turbo I will need more stall on each transmission and built front transmission too.

Decisions decisions.
 


OMG... just back from a test with the 4t80E cadillac transmission on the rear engine setup.
It is completely retarded now. Cranked up the boost a little on each engine. 1st gear starts in the back, 2nd gear start in front.

For sure a solid 9 second car on the street, although that is just from the acceleration in 1st to 2nd gear. We didn't shift to 3rd yet that is the next step.
The worry is the notorious soft 3rd gear shift of that 4t80 trans.

We made a set of two push switches for shifting 1-to 4th gear. Works awesome but the 1-2 needs to happen so fast if I don't shift within half a second I'm hitting the cutoff.
So I get a TCM820 box from magnashift and will be using that to do automatic shifting. Everything happens too fast in that car, with two shifters.

I will keep the front engine manual so I only have to shift to 3rd gear at 90 mph once and that's it.

The new trans feels much more responsive and puts the power down WAY better. I was expecting more HP loss and to feel the weight of that trans but the fact is I made too much power and had too much traction for the stock 4t65 clutch packs to hold the power. I was definately wasting a lot of HP with the 4t65 in the back.
 
Can't wait to see how this setup does at the strip. If you get a chance, would like to see an in car pic or two of the rear engine/rear cooling setup please!
 
You sure thats a 3.11 fdr with needing to run the 1-2 so quick?

Btw you can make a cheap inverter with a dbl throw 5 pin relay and control it with yer pcm fer now.

what car and year and motor is that 80e and the converter from again?
 
Turbocharged400sbc said:
You sure thats a 3.11 fdr with needing to run the 1-2 so quick?

Btw you can make a cheap inverter with a dbl throw 5 pin relay and control it with yer pcm fer now.

what car and year and motor is that 80e and the converter from again?
Click to expand...

I have bigger tires in the back and at 2600rpm cruising slow speed, no load on the rear engine it is 2200 on the front engine.
So that calculates closer to 3.48 than 3.11

99 Deville 4.6 Northstar
 


engne vin?

if you used the stock pcm youd be able to contribute data on the converter flash stall and calculated ratio.

we had that aurora converter flash stall to nearly 4k one time at the 1-2 before the mph pid made it clear we had started spinning once we shifted lol

you have the damn trans fer it, modify the range switch or install the later IMS switch/harness and use the inverter or the TEP bin fix.

that data is gonna help you aloooot
 
Ok we were able to do full throttle 1-2 shift with full staging and it is sensational so far. A real rocket. We had rain and it's still wet but no standing water. Even then the car runs 330 feet at 95 mph like a high 9 second car in the wet ! Unreal... 95 mph is just a few seconds.

Call me stupid for trying it anyways but after testing the Magnashift box I was surprised at how hard it pulled in the those conditions without feeling dangerous.

The magnashift box works well but I'm not conviced about the toggle switch shifting for manual mode as it's dangerous to downshift by mistake in the heat of the action.
The auto RPM shift mode didn't work because the RPM signal reads really dirty and all over the place. I will talk with the guys at magnashift for a better location.
I used the same signal that my AEM wideband failsafe gauge uses with success.

From a roll the car goes 40 mph to 95 mph GPS in 1.9 seconds !
 
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BTW I upped the boost on both engines at the track last time but I broke the rear trans 5 feet from the line. Which is why I couldn't get the 9s I wanted.
So now I left the boost the same but so far the trans is taking it. At least 10 runs today.
 
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