Heres a good one for you guys.

jstreet0204 · Feb 13, 2008

justinschmidt1 said:
Why would I be any more at risk than a Pi guy running 10 psi at 400 whp
and me running npi heads and cams with 14 psi at 400 whp?

In that scenario you are creating a considerably more heat because of the added boost. You could probably get away with it if you pull timing way way down but why not just get a bigger pulley and be able to have more room to play with the timing.

justinschmidt1 · Feb 13, 2008

jstreet0204 said:
In that scenario you are creating a considerably more heat because of the added boost. You could probably get away with it if you pull timing way way down but why not just get a bigger pulley and be able to have more room to play with the timing.

What would I be better off doing? running 10-12 psi?

or 13-14 with less timing?

I will be intercooled

jstreet0204 · Feb 13, 2008

justinschmidt1 said:
What would I be better off doing? running 10-12 psi?

or 13-14 with less timing?

I will be intercooled

Less boost will create less heat so it will over all be safer.

justinschmidt1 · Feb 13, 2008

jstreet0204 said:
Less boost will create less heat so it will over all be safer.

What about power?

Would I make the same power with 10-11 or 13-14 with less timing?

jstreet0204 · Feb 13, 2008

justinschmidt1 said:
What about power?

Would I make the same power with 10-11 or 13-14 with less timing?

You are gonna have so to sacrifice some power if you want to keep it safe. That's just the nature of it. You won't know how much you'll make either way until you start tuning it. It all depends on how much timing you can run at each boost level. Every set up will be a little different.

SaleenGT2001 · Feb 13, 2008

just run 10-11 lbs like everyone else and dont worry about the internals. why risk it if you're so worried about the bottom end?

04YELLOWGT · Feb 13, 2008

The only benefits you will see with a smaller pulley is more power, how much is unknown though, and it will build boost quicker. Like I said earlier though, 10-12psi is about the max for these motors if you want reliability out of them. If you got the money for a built motor and have another car to drive if your Stang blows then by all means add more boost but if you don’t you need to stay on the conservative side. Just because you make another 25-30rwhp with the smaller pulley isn’t worth risking your motor.

I forgot what did you have for a fuel setup that will play a factor in the safety of the blower too.

justinschmidt1 · Feb 14, 2008

ive got ford 42lb injectors, 90 mm LMAF, walbro 255 in tank fuel pump.

Intercooled, dyno tuned to 11.5-12 A/F I would assume

TonyG · Feb 14, 2008

I once made a post about losing 2 psi after my LT header install. Everyone was telling me that they've never seen that happen. So I investigated and found a leaky vacuum line to my pressure gauge (happened during the install).

Once that was fixed, I got my 2 psi of boost back.

hotmustang331 · Feb 14, 2008

jstreet0204 said:
Yeah that's what I was getting at. Just because you make the engine breath a little better and the boost goes down, doesn't make it safe.

Hell you can run 30lbs of boost safely on the stock block if you run a tiny ass throttle body and choke the engine down. Boost is just a measure of the restrictions, not total air flow.

Not on pump gas you wont...remember boost presure is measured inside the plenum. You would effectively still be pressurizing the intake plenum with 30PSI and filling the heck out of the cylinders....hello detonation and blown head gasket!

Basically intake manifold restriction, head restriction, cubic inch, cam shaft design, and exhaust flow have more to do with how boost effects the filling of your cylinders. If anything a smaller TB will reduce boost seen and then as a result airflow.

I do agree with your point though...cylinder volume and static running compression under full boost (whatever that may be) are really what determine how much stress your engine is actually under. Higher boost comes with higher heat....so generally lower boost is safer, even if your making the same power.

Heres a good one for you guys.

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