Twin engine GTP project progress thread

[SlowFiero]

Factory rpm limiter is too slow to use as a two step. I tried, all it did was destroy the input sprag. Two step is very helpful for spooling the turbo though. I have one I adapted from the turbo buick guys. Without it there is no way I could hold my car on the line. Now I can sit at 3000-3200 rpm make as much boost as I want and not push through the brakes. Just break transmissions instead lol. I think I ran into the same rpm signal issues you guys are seeing with the two step. It would kick in at idle. Ended up getting past that when the designer put a opto isolator on the input circuit. Now works flawlessly.

Talking to Terry at precision, he said not to run against the converter spooling up for more than 3 seconds. It will pump itself out of fluid and start chewing itself up internally. Pump also can't refill the converter by the end of the run and you end up with excess slippage in third due to lack of fluid.



Cool project, going to be interesting to see how far you can push it.

[Turbocharged400sbc]

damn and ive seen the tr6 ccp system they have....

here's that 2 step...nice
http://www.turbotweakstore.com/Produ...oductCode=1041

[TwinV6GTP]

Thanks for the suggestions. It's not super lazy. It needs at least 3 seconds to get a solid boost number.

Here's a video of our testing during the rain. We waited until it got dry but it never did.
So we tested in the parking lot of shop on the wet cement.

The 1st video shows the big turbo in the back and the other is with the big turbo in front.
You can clearly see how loose the stock 4t65-HD converter is vs the 4.6L Northstar converter in the back.

[SlowFiero]

The tr6 won't work directly due to the different ignition inputs the old 3.8 use vs the 3800. If you could sweet talk Bob Bailey into modifying it for use with 3800 that would be sweet.

That is the two step I'm using, with opto-isolator on input signal. Haven't tried the ignition retard or anything, as I'm not sure now that the signals are compatible. However the two step works great now. Just have to break the ignition feed between the coils and ignition module. I used the msd 8870 adapter blocks for the dis-4 to allow this. The old modules had a separate power input for the coils, so it's not needed or listed on any of the literature for the old 3.8L. (http://m.summitracing.com/parts/msd-8870)

I may try remote mounting the modules, and trying the dual module setup your testing. 0.025" gap sucks for driveability. This would also eliminate the need for the spacer blocks.

[TwinV6GTP]

I wonder which is the best/cleanest signal in the GTP ? In the dash ?
out of the ECM/RPM signal. Ignition module ?

Often when using aftermarket controllers I get the signal from one of the coils. That is only way to get a good signal on many machines.

[TwinV6GTP]

Update the 4t80e took the abuse so far. The testing plus the one full pass and 2 pratice passes for tuning the new injector setup.
I launched it harder than ever at 1.48 60 foot and that was still low boost launch on slippery track.

I bet this car will do 1.3s with the current setup but with more boost off the line and a real burnout and maybe 1.2s if I fix my suspension that is not able to handle the twin engine weight and power.

here's the video of the 6.31 @ 112 mph run. That means the car is 9.6 or quicker on the 1/4 mile as is and there is a ton of power left on the table.

[Scottydoggs]

the announcer seems to love it lol

keep tweaking it.

[TwinV6GTP]

Everyone loved it. People couldnt get their head around the car. The small crowd went crazy according to my friend in the stands


Sent from my iPhone

[SomeDudeAtHome]

That's very cool! So once all the engine(s) work has been completed and there's nothing else you'd want to do with that are there plans for body work?

[TwinV6GTP]

That's very cool! So once all the engine(s) work has been completed and there's nothing else you'd want to do with that are there plans for body work?

The plan is to make all the hardware integration seemless first. No sense in hiding all the wiring, cleaning up the car too much yet.
We'll make the shifter work auto on the rear engine's 4t80e at least to help make less difficult to shift. It's time to start doing some weight reduction on this 4400 lbs beast.
Get some much stiffer struts to help control the bounce from the super stiff spring preload.
If I have too much traction issues with the ET street, order another set of full slicks.
Get a built tranny for the front engine just in case.
Paint job/body work to make it cleaner looking.
I have great brakes so no worries for that.

Maybe a custom dash for weight reduction but especially to get both instrument clusters in my view.
I'm debating this. Right now I have a stock dash. I find cars with custom dash to really give out the Full out race car vibe that I don't want. I like the fact I look stock or close to when going to the line.
I had even 2 guys admit they laughed at me wearing my helmet in my GTP thinking it was a 15 second car most likely or possibly a 13 sec car. Needless to say they were really impressed by the car's performance and they said they really got why I needed a helmet with the second engine in the back after they say saw the 6.3 @ 112 mph run.

So I have to decide

[ILoveAudi]

This car is just too cool.

[Turbocharged400sbc]

and now you know why we decided not to put the new powerplants in our old chassis.

so awesome

moreso since ya'lls only other pastime is stickin them walrus's with yer harpoon

[91parkave]

You need twin LS4'a with turbos. You won't gain weight but you'll have 2 extra cylinders lol. You'll easily eclipse any goal you set prior.

[GTPpower]

Man this is awesome. Nice job on the build so far.

[Turbocharged400sbc]

You need twin LS4'a with turbos. You won't gain weight but you'll have 2 extra cylinders lol. You'll easily eclipse any goal you set prior.

they could only do it with Northstar v8. the LS4 skirt is too wide to work with the 80e output section

[TwinV6GTP]

and now you know why we decided not to put the new powerplants in our old chassis.

so awesome

moreso since ya'lls only other pastime is stickin them walrus's with yer harpoon

LOL. you guys have Alaska so Canucks are not the only ones with Harpoons...

[TwinV6GTP]

You need twin LS4'a with turbos. You won't gain weight but you'll have 2 extra cylinders lol. You'll easily eclipse any goal you set prior.

Yeah as James said, the 4t80e won't clear it. And I already proved nothing short of a full built 4t65HD will handle the load produced in the rear engine setup.

Except of course a full out race built chassis which would make it possible to use two mild built 4t65-hd. Right now my full body 4400lbs twin engine is a pig and I need a pig of a trans to go with it lol

[91parkave]

So I guess your biggest enemy Iso weight transfer etc..being unequal between front and rear? It'd be nice to be able to design both cradles isolated to a degree and have a hydraulic mean of keeping the drivetrains equal. From the video it looked like the front wanted to go all over the place on launch

[darkhorizon]

On a XP/s1x ish or smaller cam, my pushbutton antilag worked really really well from a stop. I could get full boost on a 6262 from a stop quickly on a 65e and a stock gt converter. Last I checked hptuners doesnt have the ability to do this.

[Bronco Boy]

..... since ya'lls only other pastime is stickin them walrus's with yer harpoon

Correction..... them walrus's are actually cute little seal pups. WAY easier to harpoon!