Nagasaki Noisemaker

So I'm just curious as to how much PSI a stock 3v can handle, the turbo in question is rather small and would require quite a large amount of boost to run at our WHP that we have in mind(400-450). The motor is going to be out of an 08 Bullit with 24k on the odometer.

Dino Dino Bambino

It's more a case of how much HP the stock connecting rods/pistons can handle. The answer is around 525-550 crank HP (460-480rwhp) but other variables such as fuel octane, IATs, the quality of the tune, and how hard you drive the vehicle will also come into play. Preventing detonation is key.

Nagasaki Noisemaker

Thanks for the reply!
So the amount of boost isn't really a major factor? We did the math and for us to make the efficiency of the Turbo work it would require 24lbs of boost to make roughly 450whp, it's going to be tuned through VMP more than likely and will be ran on 93 and E85.

danzcool

11psi, in a turbo setup, can get you about 560RWHP in a 4.6L 3-valve setup. Most think this power level is asking for trouble, so probably best to keep it around 8-9PSI. Here's a video of the dyno test many years ago after my turbo kit was fabricated, prior to pushing it or installing a built motor.

At 24PSI in a turbo setup, you would likely be pushing 800+ RWHP, which is definitely above the safety level of a stock 4.6L block... but I've got a vid of that also.

**edit** By the way your math is wrong, or you are trying to be too clever. normal air pressure is 14.7 PSI, but when talking about boost this is the baseline of 0, air/fuel mixture is steady regardless of how dense the air is, so if you are putting twice as much air (14.7PSI) you are also putting in twice as much fuel, and all things being equal you have doubled the power output. SO the pressure you would need to hit 450 RWHP is based on what the car makes RWHP as a naturally aspirated engine... assume it is bone stock to begin with and is probably putting out 270RWHP, so to get to 450 you need 2/3 more power (450/270=1.667) 2/3 of 14.7 is 9.8PSI
A tiny single turbo that can put out 25PSI on a 1.6l 4-banger will not hit that PSI ever on a 4.6L V8, it will probably only be able to hit about 8PSI because you are filling about 3x the volume in the cylinders.

Dino Dino Bambino

I use 290rwhp as a 0psi boost baseline as it's roughly what you'd have with a good CAI and a 93 octane tune with all else being stock, and a turbo set up would have those anyway.
Assuming the turbo doesn't consume any HP (unlike a belt-driven supercharger), you'd need to raise the intake manifold pressure to 450/290 x 14.7 = 22.8psi. That's roughly 8psi of boost. However that assumes that you have perfect charge air cooling with an intake air temp. (IAT) close to ambient.
Higher IATs will reduce air density and predispose the engine to knock, triggering the knock sensors to reduce ignition timing advance. The consequence is reduced HP output. That's why it's so important to have an efficient intercooler.
Nagasaki, it's better to get a larger turbo that's suitable for the engine displacement. That way you won't need to spin it as fast and it won't have to work as hard to generate the same amount of boost as a smaller turbo.

Derf00

https://www.hotrod.com/articles/hrdp...-ford-mustang/

Check out the article, pretty informative on stuff that breaks and limitations of things like the motor and transmission.

Tiger_germanTech

you and Dan’s replies are excellent. Thank you for the quick reminder