Hey everyone, I bought an 87 350 IROC a couple of months ago and started taking it apart a few weeks ago. The drivetrain is strong running but has quite a few miles on it, 290,000kms or 180,000 miles. Anyhow, I had been planning for a twin turbo build up using most of the stock induction components, ported and polished and whatnot, and some Aluminum L98 heads in place of the iron ones on there.

I work as an aircraft mechanic full time, as well on my days off I work casually at a local Corvette shop, so I have access to good deals on used and new parts. However, recently my crewcheif at my full time job quit, and is moving away up north, he is currently building a 35 Chev coupe, and has lots of parts/ engines/ blocks laying around and cant take them all with him, so I picked up alot of his leavings. I got a virgin 400 small block, a 350 block, late 70s 4 bolt mains, a set of 882 cylinder heads and some other various components.

Now if this is in the wrong section please feel free to move it,

Im wondering on what you guys think I should do, should I stick with my original build plan, of a twin turbo 350 L98, running 8-10ish pounds of boost on T3/T4 hybrids, or should I build a big cam, aftermarket intake (Stealthram or Miniram), nitrous fed 406? Or, better yet, a Twin Turbo, injected 406?

I realize the tuning issues I will have either way, and will likely switch to a MS3 engine control system.

Some more details on the build, if I were to keep the stock L98 intake components and do a twin turbo build on the 350 I would simply rebuild the 700R4 to handle the power, however if I wind up going to a big cammed 406 I will be looking for a T56 to swap in.

This car will not be a daily driver, it will be used during summer for cruising, occasionally driving to work, a few trips down a drag strip likely. Things like that, mileage and street manners are not of the upmost priorty for this car.

I intend to build another car, (looking for 305 5 speed Camaro or Bird to build as a dedicated autocross car).

So what do you guys think I should do, 406, or original plan of TT 350?

 

Twin Turbo 406.

 

not with a factory block even though some of us (me) is doing it anyways

the 3 main questions are

#1 how much money do u want to spend
#2 do u have the skills to do ur own fab work
#3 and last but not leat how much power or how fast do u want to go in the 1/4 mile

 

Twin Turbo 406 with splayed mains and forged rotating assembly.

 

even with the splayed mains the 400 block isnt as strong as a good 350 block
the turbo(s) will make more then enough power to spit the crank out the bottom

if he wants a good bit of power a shp 400 block would be the way to go
but for most ppl a pretty mild 350 and turbos will make more then enough power

that being said i picked up a 406 with forged dish pistons for 75 bucks , the plan is to put it back together witht he pro comp 210 cc heads and boost the hell out of it till i end up running over the crankshaft

im also only putting like 600 bucks into the engine so no big loss when i do run over the crankshaft

the current 355 has 882 heads , megasquirt, tpi , twin 57 mm turbos and is an absolute blast to drive , off idle boost and good power till around 5,500 rpms @ 8 psi it make more power then u really want for the street

at 18+ psi its a straight up rocket

 

Whats the question? One build is easily 5 grand or more than the other and a whole new balll park of performance. Why are these your two options? Makes no sense to me