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imported_Ron Vogel
Guest
It's not exactly psi that does it. Generally a hydrolock condition causes it. Either by too rich a mixture not ignited/high boost, or by a lot of ign advance/boost/fuel not ignited properly. Then generally, a lean condition/high boost will cause a piston problem, ring lands tend to disinegrate in the path of the intake valve.
There are many running 15-16psi with an M90 w/no head gasket problems whatsoever in the presence of correct tuning. The most you will realistically see with a Gen 3 M90 is 15-16psi, IIRC the gen 5 will max 16-17 psi.
I run a 2.8" pulley on my daily driver, usually see 14psi +/-, and am running 22 degrees of timing. As long as the tuning is on, and you don't have KR you're golden. Soon as my alky system is up and running, I'm putting on a 2.6" for daily driving. I don't have a aftermarket cam; only 1.9's.
There are many running 15-16psi with an M90 w/no head gasket problems whatsoever in the presence of correct tuning. The most you will realistically see with a Gen 3 M90 is 15-16psi, IIRC the gen 5 will max 16-17 psi.
I run a 2.8" pulley on my daily driver, usually see 14psi +/-, and am running 22 degrees of timing. As long as the tuning is on, and you don't have KR you're golden. Soon as my alky system is up and running, I'm putting on a 2.6" for daily driving. I don't have a aftermarket cam; only 1.9's.
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fastcash
Guest
If the most you are going to see is 15 psi then why even drop pulley sizes? i have a 3.4 with almost 14lbs of boost. (if i did the calculations right 
) But, if you see my signature you will see i will be injected also, real pro type shit too. But why drop pulley sizes when i can increase timing 3-7* and get the same effect. (ilovealky)
) But, if you see my signature you will see i will be injected also, real pro type shit too. But why drop pulley sizes when i can increase timing 3-7* and get the same effect. (ilovealky) Because boost does not equal power. This is a mistake so many make. Flow equals power. There are W Bodies out there running 10lbs of boost that could easily hand you your quarter panel in a race.Originally posted by fastcash420+Mar 6 2005, 05:03 PM-->If the most you are going to see is 15 psi then why even drop pulley sizes? i have a 3.4 with almost 14lbs of boost. (if i did the calculations right
<!--QuoteBegin-Ron Vogel[snapback]74050[/snapback][/b]
well with 93 in her, my boost gauge says 15-16psi...on my scans 14-15.7psi. this is with 6 degrees of timing.(slow setup) when I have race gas in her I see my boost drop to 11psi, and my timing 18.5degrees.
I havent popped my head gasket yet.....knock on wood. I will tell you how much boost I have when it goes
I havent popped my head gasket yet.....knock on wood. I will tell you how much boost I have when it goes
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imported_Ron Vogel
Guest
Well, you are reading manifold boost, not cylinder pressure. You can stack boost in the intake all you want, but it'll never get in the head if it's too hot or you have a ton of exhaust backpressure, or poor scavenging. The whole point of dropping pulley sizes is to fill the cylider with air and gas, have it go boom, and expel it. Most shoot themselves in the foot by dropping too much in pulley size before they can use it. That's the reason IC'd or cammed cars typically have lower boost readings. It's not stagnating in the manifold, but being utilized by the motor.
No. You will need a smaller pulley. What I'm cautioning you against is confusing boost with flow. My engine with a 3.0 makes 14lbs of boost and "flows" more air then your engine does with the same 14lbs. Therefore, I'm making more power.
You got me on this one. I've never heard of boost dropping when changing fuel. I would presume you have another issue bringing up this problem. The reason your timing jumps is because you're not knocking with the 11psi.
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fastcash
Guest
what i am saying is, if i FLOW throughout the whole process, dropping a pulley sooo far, is not really that necessary?
And one more thing, i would never confuse flow with boost. But ron did make something clear in his prev. post. So i do understand dropping pulley sizes, and i will be doing that (see sig) i just was a little confused on the m90 max out factor
And one more thing, i would never confuse flow with boost. But ron did make something clear in his prev. post. So i do understand dropping pulley sizes, and i will be doing that (see sig) i just was a little confused on the m90 max out factor
I'm not sure what you're asking?
Assuming you're asking if dropping a pulley is necessary the answer is no, but if you want to go fast you'll want to drop a pulley or so. Supporting mods such as cams, rockers, open exhaust, ported blowers, etc all help to increase flow but all will also drop boost with the exception of the ported blowers. Now you're able to run more boost and flow even more.I already ran water injection. I pulled it off!Originally posted by fastcash420@Mar 7 2005, 12:31 AM
well, i am going to love this set up. As a matter of fact, as soon as it is installed, i will call you and bring my ride out there so you can drool all overit
now to start saving for my tranny rebuild!
[snapback]74125[/snapback]
But bring it nonetheless and I'll see if I can scavenge some drool.