[V8] V8 Twin Turbo?

[Tony and Lillie]

We toyed with this idea a lot when I was in the Air force and more actively 
doing engine swaps. Here are a couple of things we observed.

1. Basically, the PT is two 1.8 16V's together, with a one tenth higher 
compression ratio. This means the copper headgaskets available for the 16V 
will also work on the V8 to lower compression, if that's the way one wishes 
to go.

2. A set of bigger cams will lower the dynamic compression as well. However, 
they tend not to be cheap. (This is the trick I used on the 351C to run 
10.5:1 and still use 87 octane)

3. A set of bigger turbo's (we were thinking K26's or T4's) will spool 
slower, which will help the fact of early detonation. I would also combine 
these with large intercoolers, to help more with keeping pre-detonation at 
bay.

4. The biggest thing for us was the fueling. I suspect that the Motronic can 
handle some additional playing, perhaps at the expense of cold start 
driveability. I would certainly run an aftermarket chip (IA, ABT, etc) with 
the Motronic. I was also thinking about the 24lb Ford injectors and an 
adjustable FPR to help out a bit. We were leaning toward running about 
4-6psi for boost. Believe it or not, that little bit makes a big difference. 
We played with the 5000TQ and a 1.8T to see the difference. On both, we were 
able to nearly completely eliminate boost (more so on the 1.8T) and drive 
them, then run them with boost pressure. The 1.8T was completely adjustable, 
so we played a lot with it. I was surprised at how much difference any 
pressure made on a turbo!!

Anyhow, we were thinking in the 325-350hp range, on a completely stock 
engine with big turbos. Oh, and this engine was to go in a 90Q, so it would 
have moved nicely ;-)

I don't think I'd do this with the auto, though.

Just my .02,
Tony


----- Original Message ----- 
Subject: Re: [V8] V8 Twin Turbo?


> Here's a thread on TT's on a PT.
>
> http://www.motorgeek.com/phpBB2/viewtopic.php?t=31421&postdays=0&postorder=a
> sc&start=0
>
> There's a lot of discussion on which turbos to use, and he's running
> standalone engine management. Not much in the way of resolution, but it's 
> an
> interesting discussion.
>
> One interesting thought was K26's. At about 12 psi around ~3200, and 1.8L
> and 16v breathing per side, the thought was they'd be good for something
> around ~230-ish per side. A 450+HP PT would be something.
>
> Of course, how to plumb, WGs, and whether the internals could take it are
> all questions to consider.