A set of PT-67'S are GREAT turbos and will make 1300 hp like nothing. You will wish you went turbo many yeasr ago after having them. I cannot describe how great it is to make such huge power all day every day. The car will drive like stock, but make insane power at the push of the pedal. No need to fill a bottle, throw belts, or loud whinning.
Part of the reason to go with smaller cubes is efficiency and need. A Turbo can make up for cubes with boost up to your octane limits, after that, it is time to increase cubes. A typical 330-400" turbo motor will make an easy 1200-1500 hp under 30 psi on 116 octane. Do you need mre then that?? If you want to build the ultimate pumpgas engine, a turbo 800" mountain motor will make an easy 1800+ hp on 93 octane pumpgas.
The downside to massive cubes on the street on a turbo car is the efficiency. If 80% of the driving is done at part throttle, a 350" motor will suck about half the fuel of a 540" motor. So for a mostly street driven car, I would go small cubes for efficiency and weight, and cost savings.
If I wanted to race and had a chassis car, I would build the biggest motor possible and slap a turbo on it!

Well a smaller motor would run less fuel,but this isn't a DD so we aren't really worried about mpg.

Pt-67's what mm are those,This going to show my knowledge on turbo's,I know turbo's work on gas pressure etc,so how do you set the psi on one.Like I said this a new beast.

My brother been running a 10.5 car with a nitrous 555,and has been talking about a but turbos on a 706,I told him I wasn't ready to play with that kinda monster yet.Plus the chassis work needed to make a turbo car leave.I have raced acouple turbo PM's and they are a IMO more bitch to may leave than nitrous car.

Thanks for all the advice,help guys

A PT-67 is a 67 mm turbo. Boost is controlled electronically through a set of wastegates on a twin setup. The wastegate is a valve that either stops or allows exhaust gas to bypass the turbo. If the valve is open all the way, very little exhaust from the engine goes through the turbo, it spins slower, and you get little boost. If you close the valve all the way, all gasses will go through the exhaust turbine and turn it as fast as possible. If you did not run a wastegatem, boost would probably climb upward of 50 psi depending on the setup. This would be bad.

and remember that a PT67 will support almost 800 HP, so two will support 1500-1600. Obviously dependant on the engine combo and boost level.


So again, what is your desired HP goal? You don't want too large of turbos either, as they'll just be soggy, boost will lag, etc.

Jody

Good point.

You should specify what you want the car to do.

-Motor size
-Car weight
-Exact intended use
-Realistic power that the motor will really see

These are the most important things, this will at least get this in the correct direction.

the car this 499 idea is going is a pro street corvette,cruise night,car show cruiser,not raced,I'm not sure why they built a 648 for it anyway,but what the hell.

Basiclly my buddy like's the idea of TT's and wants the around the same hp has the bb.which it's in the 1000hp bracket on the motor.this part i have taken in to thought,it was what turbo's to use and etc.that I was in question on.

the wastegate/blow off valve must be what cause's the burst of sparks or flames under turbo cars at mid to full throttle.

the car a 5 spd lenco in it for a tranny.so it wont break.

this is one of those over hp car's,and the guy has more money and not enough stuff to spend it on.

Step back and re-think what's the goal here.

~1000hp with reasonable manners and durability for a Pro-Streeter.

That being said, a 499" combination may or may not work well. The key is to build the combination for power and reliability. Having thick/strong bores, proper pin height for a strong piston and well placed ring package, good rod/stroke length to control piston speed and side loading etc all factor in.

Next...having a set of proper heads that will be efficient with the engine size under them.

That being said, I would consider a 427 or 434" SBC using a tall deck block, a well prepped set of 18* heads would easily do the trick. Consider a pair of PT70-76mm compressors with S trim wheels and a good intercooler. This is a solid foundation w/ plenty of room to make additional power.

He does not need all that for only 1000 hp, that would be way overkill.

Does'nt really sound like he even knows what he want for sure anyway.

I agree but.....

Would you recommend a pair of TO4E's and 23* heads on what he's after? I wouldn't. That's why I stated the obvious and explained how much room there was to grow with that setup.

It can be done w/ a simple 355 combo.

I'm doing a TT572 Hemi w/ twin 88's for a customer that never has the intentions to use all it's capable of. Is it efficient for what he's doing right now? No but, it's kinda the same deal...he wants the "bling" and has the money to pay for it.

No I don't, I have been try to get him to decide what he wants to do,the engine's not a problem to build for me I pretty well have it figured out,build it with the same crank,rods,pistons I would for a nitrous motor.then change the cam and compression ratio.

I was thinkin about using the same heads I did on the other engine's,15* heads then use a sheetmetal intake.

But right now I'm resreaching this out.