Ok,

So I have come to understand quickly a twin turbo car is a tall order however running efi ontop of that seems to be unheard of. My goals are a SBC stroked to a 383 running twin turbos and fed by a efi system.

Reasons:
I have come to the conclussion running a SBC is the best bang for the buck, also running a 383 motor will work best in my plans or so I think. I want a DD car(thus leaning towards efi) that is good on gas but gives me the power when I need(thus the turbo portion).

I am wanting the 383 to run in the ballpark of 300-400 horse and hopefully be around 15-20mpg the closer to 20 or over 20 would be awesome. So my thinking is the torquey qualities of a 383 coupled with a twin turbo set up to spool me up so High horses when I want would be perfect.

Compression thoughts: I have seen several people comparing a 11:1 to a 9:1 and while the general school of thought is low comp is needed for forced induction(or so I have always been told) the people running 11:1 have said that it is far more fun and overall better then any 9:1 they have owned or driven keeping in mind all are turbo'd similarly. In my researching 9:1 seems to be the common choice as it allows for a much larger room for error and that is the only real reason.

Im trying to keep this short as in reality im looking for insight not to write a novel. Im planning on running a tremec magnum primarily for its 6 speed box but a TKO I have been told would fit the bill also(lacking the 6th gear of course). Rear would be a open 3.73 and the kicker its going in a 78 trans am(plenty of space to drop in a sbc with twin turbos).

Im currently running a late model 400 making 250ish hp and a broke as gm350 that is well dying. as far as the rear I dont know whats actually in it till its opened up. However the cost to rebuild the driveline in this car add up to slightly less then my estimates to run a turbo minus all the materials needed to allow the swap(k member, linkage, blah blah blah). Keeping in mind the ideal rebuild would be making the car have the power I sometimes want but dont need day to day(thus what strayed me to change everything) I am asking on here as I have owned a few thirdgens and you guys take questions straight forward unlike most places trying to convince owners to work with what they have. So any insight to my lengthy question would be great.

LASTLY, GOALS(in a nutshell):
My goal is for a bullet proof 383 that can handle huge psi numbers, but run on the lower end of horsepower without the spool'd turbo. Thus yielding a long lasting good on gas torquey motor that can impress at WOT when I so choose to get those turbos going.

Thanks in advance
-Alex

 

EFI and turbos are nothing new FYI.

and unless you build a driveline and suspension to utilize the power your making, your really just wasting money and HP.

look up Orr's build on here, it's a sticky in the "power adder" section and is pretty much what our planning on doing but it's an automatic

Good luck! Its very worth it in the end

And oh yeah, take your budget, multiply by 2 or 3, and thats what it's really gonna cost you. Ask me how I know....

 

Well I kinda had a feeling what im looking to spend will be a good bit more once im done, alot of money too in my "conservative" estimate banks on using quality turbos but ive been reading up a bit more on the "ebay" turbos and seeing if those might suit my occasional use better. As far as the rest of the car goes, its going to be rolling on a pro-touring setup sub frame connectors and all. I just dont need a car that is a gas guzzling snot ripping monster everyday just something that has the ability to be that when I push down far enough. The car to be honest probably will only see the track once or twice a year.

Also I have been reading a good bit on Orrs thread very informative.

 

May be easier to just go single turbo. Still can do all your goals and be cheaper in the end by alittle bit

The motor get it built with all forged internals and a 4 bolt main block, preferably a splayed conversion. A hyd roller cam setup should be considered. Better for street operation.

Turbo sized for your power goals. If you want alot of power you need alot of boost and thus 9-9.5 to 1 comp is best.
The rest is all fabrication and where you put things in engine bay and heat management