Heres the deal boys and girls... I'm bored as hell with my 355 TPI and my t-5 tranny.... I got my signing bonus a couple of weeks ago and i want to build a 427 twin turbo... I can build the 427 no prob... but i don't know anything about turbos besides what they do and how..... anyone wanna show me this set up or expline what turbos to get etc....?

I saw this setup on a c-5 corvette and it claimed 900 ft-lbs of torque and like 875 hp.... so i have a feeling im gunna have to throw the t-5 in a junkyard and beef the hell out of a T-56 any help would be much apreciated and im gunna start posting pics as i go along on the project

Here ya go:

Read This

If you read through that, it'll give you a good understanding of how to do it. Many here have done it. Good luck!

Exactly what I'm doing,except with one turbo.Got the turbo,block,crank,rods and soon the heads.Problem I seem to be having is with the pistons.Trying to find them to match a 4.125" bore,4" stroke crank,6.000" rods AND dished enough for around 8.5:1 CR on a set of AFR 74cc heads.Looks like I'll need a custom set from JE etc.I'm running out of children to sell!D

you cant build boost in neutral... meaning no launching on boost with a manual tranny, this can be a good thing for a stock rear end, or a street car where wheel spin is a problem.... but IMO opinion if your gonna spend all that money (it wont be cheap!!) then you should do it right, and that means a beefed up rear end, and slicks... and an auto with a nice stall so you can launch on a good amount of boost

I finally found a 400 sbc out of an old GMC truck.... Now for some boring and honing i'll have pics of the cleaded up block later

if you had the money, StrokerMotor.com sells 427 SDC's with forged internals. Expensive though.

EDIT - Not Strokermotor.com, www.theengineshop.com/sbkits.shtml

What turbo are you going to run? All weekend I was looking through compressor maps trying to find something that would work good on a 427 and I couldn't find much of anything that seemed to work well. I wanted to run a single but I think I'm gonna end up working on twins. Also, how much boost are you going to run and how much power are you looking for?


Stevedave: why can't you build boost in neutral? Not enough load on the engine?

exactly... i have been talking to people on turbomustangs.com, and a lot of them are running twin turbo coupe turbos, (the .60/.63's) and a lot of those guys dont even get full boost in first gear... they get some boost, but not full boost till second gear, dont get me wrong they still work great, many guys are hitting 10's on stock shortblocks

Are you sure about that? I was able to build boost in my Mustang SVO at the line (launch on boost) and this was with a 5 speed. Alot of Buick GN guys runs stalls matched up with their turbo so they launch on boost. I've never tried it in my blown 91 Z. Are you speaking from experience or word of mouth?

You do know your not going to get a full 427 cubic inches, just from boring and honing. 406 with a .030 overbore.

Still a 406 twin turbo would still be fun.

You can still build boost with a good programmable EFI system.

What some of the import guys do, with their smaller engines and manual transmissions, they have a neutral program that dumps rich fuel and sparks late, which means there is still a lot of burning going on when the exhaust valves open, which means that you can build boost with next to no load. As soon as they let the clutch out...the computer goes to the loaded fuel/timing programs.

Of course, with an auto, you don't have to let off between shifts and re-build boost, but there is another way around this...

...World Rally Cars, I think, also switch to rich fuel and late timing between shifts, sometimes with heavy ignition going on inside the exhaust manifold...which is what you hear when they (and some manual turbo drag cars) pop-crackle between gears, and it keeps the turbo spooled.

But, you will probably want to go with a proven and simple combination of turbo+automatic because setting up things like that can be hard.

By the way if you still want to go with a built T56, in case you haven't heard of these guys, take a look:

http://www.gforcetransmissions.com/tran_gt-56.asp

A factory 400 block (4.125" bore) can take a 3.875" crank with proper clearencing. John lingenfelter has it in the back of his book as one of his "proven combos". This with a .03" over sized bore will give you 420 ci. Go .06" over with it and your at 427 ci. He did say that going .06" over on a factory 400 block is a no no due to the loss in strength. This could become painfully apperent on a boosted app.

I just didnt see where he posted about using a diff stroke crank. I dont know if i would want the .060 overbore, with a boosted aplication, if it had to be that much overbore, i would use hard blok, or whatever the name of the water jacket filler is, to keep the cylinder walls from flexing.

Kevin

I'm going to use a 62-1 which some may consider to be on the small side.A very streetable 600+HP is the goal.I'm a newcomer myself to turbocharging so we'll see how it goes when the motor gets put together.As long as the turbo gives me what I want then I'll be happy(for at least a few months anyway!)

I'm sure most of you guys already know this, but the Innovative Turbo camaro is running a 427 with twin turbos. They could probably answer some questions you might have.

Thats the thing, we're both thinking of running single turbo's, little different in the airflow department.

erictheviking, I guess my next question then is how much boost do you plan on running? With a 427, I figured that at 5500 rpm you'd need about 68 lbs/min of airflow for 10# of boost, which puts you far to the right on the map. I think you'd be better of running a T66 because your in a better place on the map and if you want to run more boost, you'll stay on the compressor map and run higher efficiency. Atleast from my understanding of compressor maps.

Crazy Joe's (Mike Sitar's dad's) twin T3 (60/.63) 351 powered mustang doesn't see full boost till the middle/top of second gear with an auto.

Assuming 65% compressor efficiency and 70% intercooler efficiency, you're talking about 63lb/hr without an intercooler and 75lb/hour with. (adjust those numbers whichever way you're comfortable, those were done at 100% VE so flow numbers would probably be a little lower real life, but you might need more to deal with any losses due to plumbing/intercooler…). Anyway, the point is if you look at the maps, none of the turbos that you guys are discussing are in their efficiency range anywhere near there.

Is this going to be a major problem/cause damage or will the set up just not be as efficient as it ought to be.What I'm getting at is can I run this turbo for a while and not have any problems,just not getting the power I could from a 427ci.

It just won't work right, the engine will just fall flat on it's face whenever the compressor efficiency drops significantly below what is mapped, I'd guess around 4000rpm (I could figure it out relatively exactly, but I'm not going to waste that much time…).

Look at the attached picture, that's your 62-1 compressor map. The red line is roughly 10psi, the blue line is the 75lb/min that I mentioned earlier and the green is the 63lb/min… you're not even in the right ballpark for an engine that large.

I've said it before and I'll say it one more time, someone saying that X turbo flows Y cfm, or "enough to feed xxxHP" is just demonstrating their ignorance of how they work without quantifying it more (say something like xxxhp at a pressure ratio of y… or something). You can't just say "well, this turbo is good for xxxhp and that's more then what I want to make, so it will work." Yes, airflow is proportionate to power production, but centrifugal compressors are pretty dependant on the conditions that they're operating under to determine what their airflow will be.

oh sorry I didnt know we were talking about full boost.