ibkevin

That sucks to hear John.

I have been into the 21lb area a few times, unintentionally, on 91 RON with a two year old Widefire gasket. The ZT2 has shown John's stage II has held the A/F very nicely.

I also learned I can hit max boost at <60% throttle, I keep my foot out of the floorboard these days!

eclou

Bill in D, how many people here have blown HG's even at 15# let alone 18#? I think you are in the extreme minority of people here successfully running over 20# without water/meth injection. If you can name more than 3 people I would be surprised. I am envious of you, but not foolish or brave enough to push my luck.

lart951

I have ran 21-23 psi for the past year on 91 pump gas and a mix of 10% xylene for extra precaution. I am trying to tune my car for a max of 25psi with 20% xylene.

nize

i'm curious why people are quick to suggest a widefire gasket when the only use for such is an o-ringed head. if the motor hasn't been o-ringed, there is absolutely no difference wether a widefire or non-widefire gasket is used.

lart951

Agree

billindenver

You are making an assumption. That the BOOST is what caused those failures. In a way, you are making my point. Even low boost will pop a headgasket if A/F and heat are not looked at. Take care of those two and you can run 20+ without any trouble.

On a car that is as cheap as a 951 can be, there are a fair number non mechanically inclined people doing their own maintenance. Not cleaning surfaces enough on a HG change, not checking head and block for flatness, no A/F meter in their car and running more boost than their fuel delivery is set up for. That is not the boost causing failure, it is mechanical ineptitude.

Nothing wrong with that, you have to learn somewhere but if you are blowing headgaskets at 15# of boost...you need another mechanic.

ibkevin

I wasn't hanging from my laurels nize, just stating facts.

eclou

The BOOST is not necessarily the source of the failures - agreed, but it sure is effective in unmasking some other shortcomings/flaws in the motor. As you have alluded most of the modded cars (including mine) are at less than optimal state of tune, assembled by less than professional hands, and that gives you far less headroom for mistakes to go unnoticed.

There are however a couple of factors inherent to the motor design that may make it less tolerant of boost than other cars - open deck block, steam pockets at the rear of the head. Also many cars also have already blown a HG in the stock configuration early in the lifecycle and as such it is hard to know if the plane of the head (let alone the block) has ever been checked.

Couple that with the fact that most of us run dated chips, limited fuel massagers (my 3-4 channel ARC 2), crude boost controllers, and a grocery list of used/eBay parts (almost my entire build is second-hand eBay sourced), is it surprising that most of us 3rd, 4th + hand owners avoid honing the car to the bleeding edge?

billthe3

I like how everyone capitalizes BOOST. It makes it sound like some sort of fancy drug or something.

toddk911

So the 10% mix put you about 93/94. So you were running 21-23 on "pump" for most of the US.

toddk911

BOOST DOES NOT BLOW MOTORS/HEAD GASKETS.

HEAT, in essence, blows head gaskets.

lart951

correct and I try to keep my A/f ratio 11:5-11:7 at max boost

amschnellsten

tune your car and you should not have so many problems with headgaskets. Take it to a dyno, have a airfuel guage in the cockpit and watch it.

JBrown

Thanks for all the replies. I am not saying that it blew because of high boost. Again I had vitesse stae 2 with smt-6. It was not fine tuned. I was told by lindsey racing running more that 18lbs is not safe on a factory set up. For what reason I do not no. I am going to get everthing checked out when the head comes off. I will keep you informed
Thanks John

billindenver

Neither do they.