we have a car that is doing 475hp / 401 tq - 20lbs - 750 injectors - stock everything - 3mil head gasket - my favorite car we have built to date, cold starts and idles like stock, daily driving is no problem, comes into boost at 4600rpm - hold on tight and you better be aiming straight -
will break tires loose 1,2,3,4 gear!

 

I'm running 21 psi on turbo blue (110 octane and well over 500 whp) and I have no issues at all. I would imagine that 25-26 psi on C16 would be just fine also.

 

The truth is in the results.

While there are some freak engines (or brave souls) out there, on pump gas, most tuners will stop at 10-11 psi on stock compression and 20-21 psi with the 3mm headgasket. That doesn't mean that an aggressive but safe tune won't be able to push those boundaries, but those numbers appear to be safe guidelines.

We stopped at 19-19.5 psi with my setup, not because of the tuning threshold but more because my turbo was out of steam.

These guidelines ONLY relate to the safe tuning window, not the actual torque numbers that the engine will produce. Depending on the setup (manifold, turbo selection, hundreds of other factors, etc) a particular boost pressure will lead to dramatically different torque curves, and therefore, engine stresses.

 

There is a limit of pressure you can push into themotor. if you reach the pressure limit your gonna, A: blow a gasket or ring B: your head is gonna lift off the block C: piston is gonna let itself go.

Yes a good tune is of upmost importance but if you dont have a good solid bothem end setup your gonna eventually lose the gasket that you will keep replacing down the road or you might end up with head lift.

Also PSI of boost is a mesurement of restricton.

A ported head/intake with the same psi level of another car without a ported head/intake is gonna make the same power with less boost cause it has a lower degree of resistance.

Over the years of me messing with FI having a lowboost with good flowing head and intake will outperform a high boost unported head and intake.

 

ok i just got the inlinepro kit, 880cc injectors, 3mm headgasket, i was thinking safely 15 pounds on a precision 67/76 turbo.... any suggestions? i wanna go more but i dont wanna push it

 

If you've never been boosted, your car is going to feel like an absolute monster. Don't worry about running an extra 2, 3, or 4 psi. For the first year your ass won't be able to tell if you're at 380whp or 450whp cuz your brain is going to have to do some adjusting to the rate at which everything happens.

Sometimes people get so hung up on dyno numbers and forget that their car went from being quick to performing within the top 1% of cars on the road. If you're into drag racing I completely understand concern over the ponies and pushing the envelope...but you'd better think about having something along the lines of "Inline Pro Converted Rear End" in your sig if you are drag racing with 400whp.

 

Please start your own thread. Try not to hijack.

 

it sounds like a reliability issue for you. Just keep it at 15psi or under and you should have no problems at all. Again, like someone said earlier.. it really is dependant on the tuner.. you could kill the motor without FI at all with a standalone if you really wanted to. But, if your tuner is "good" and knows what he's doin.. 15psi should be plenty safe and good for really really good power.

 

I'm pretty sure that no one is listening to me, the guy boosting almost 20 psi on pump gas with a safe tune on his daily driver. A good tuner should be able to go even higher than that. Like I said before, we stopped not because of the detonation limit, but because the turbo was maxed out. One or two more pounds resulted in no more power and lot more hot air. Other turbos may not experience this.

With a good tuner, the 3mm HG, and 93 octane fossilized dinosour, 20 psi should not breach the tuning limit. Period.

Your motor might explode from excess cylinder pressure (torque) though...

 

The question is just too vague to give an answer. You should be asking how much HP/Tq you can make with stock block or with 3mm HG. It can't be based on boost pressure. The amount of HP and/or Tq and resultant cylinder pressure, assuming that all the internals are healthy, that a stock block can take is more or less a constant so this should be used as a measure as opposed to boost pressure as boost pressure is dependant on what turbo you are using, so the resultant cylinder pressure that is being applied to the engine could differ vastly.

Primarily it would be dependent on your turbo selection. In simple terms, one setup can be running a T4 and the second a T3 for example. They would both be making considerably different Hp and Tq numbers at the same boost pressure. IF, everyone here is ASSUMING that you are talking about a GT30/35R (which is the norm selection here), then your guesses are more quantifiable. Don't be misled by 'What psi is safe' answers.

Make sense?