The stock 03/04 head gasket is thicker than the n/a cobra gaskets.
Highest compression for boost?
- Thread starter trxcobra
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The stock 03/04 head gasket is thicker than the n/a cobra gaskets.
I thought compression ratio and boost was restricted by fuel. Not so much boost. If you have the proper fuel(s) I thought your budget was the limit. I've seen builds with 12:1 and 13:1 compression and upwards of 20+ PSI of boost on E85 and E98. Or am I missing something here?
No I think you got it. They're talking about pump gas.
What is the oem compressed gasket thickness for both? I can't find it anywhere.
.038" for 99-01 cobras. Not sure for the 03-04's, NA will chime in with the specs I'm sure. I've found most companies state they use a .036" compressed height for their compression calculations.
Most use .036" compressed height and 8.933" deck height to calculate their compression vs stock at .038" and 8.937" (some do use 8.937, just depends on the company)
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you are correct.
In response to my first post. I did say not the " most efficient "... With his compression I wouldn't think he would lose large amounts of torque with a little bit of cam tuning. Of course, I realize that does have to do with where they are now. And, NA is absolutely correct. It has been proven time and time again more compression makes more power. Period!!! You can get into a lot different variables and arguments, but, compression makes power. As for the manifold pressure of "only" 5 psi. My Cobra when I got it was remanned with a 9.1:1 compression build and everything else stock. I got it retuned and did some playing with it. Stock intake manifold, BBK 62mm throttlebody shorty FRPP headers, Bassani X with cats and Borla mufflers. 412HP at the wheels with a mere 5 1/2" @ 6500 rpm. I do not know what the cams are degreed at otherwise. I would say at a completely stock location with the sprockets. So pressure, at almost any amount does make a difference...
one thing i was reading a on this site months ago is that running high compresion and low boost will result in higher cylinder temps at tdc. idk the exact increase i just cant remember but my new motor is 10.0-1 and will be at 14psi on the eaton. im getting tuned for 91 with meth since there isnt alot of e-85. seams better than 8.5 at 18psi and heat soaking your blower.
:rollseyes
I can't even fathom how this post even relates :shrug: What does this prove?
So an NA Cobra engine on max boost will make more power than a Terminator engine running max boost on pump gas? I've never seen that happen perhaps you can "elaborate".
what do you consider moderate boost?
Already briefly addressed that in post 27. It's pretty general numbers and not exact,. but close to the real world results.
High compression AND high boost will result in even higher cylinder temps than the scenario you described. Basic physics.
14 psi @ 10:1 running 91 swill :uh oh:
You’re nearing the detonation limit of 8.5:1 at that boost level and octane. I think with that compression you wouldn't want to exceed 8 psi
Yes 10.0-1 at 14psi is way to much for pump gas if you aren't running a ridicules safe tune. That's why I will be running the meth to boost the octane of my fuel. And talking about a stock 03-04 motor making more power with max boost than a n/a cobra you have to consider the forged vs. non forged bottom end. The forged will take a lot more aggressive tune. But a forged 10.0-1 motor should be able to handle an aggressive tune with 14psi. I guess ill see what she makes when I get my tune.
As stated earlier. Disregard the fact the NA Cobra engine doesn't use a forged bottom end and let's pretend it does. A forged bottom end will handle a higher load but is no match for detonation and will crumble along with the best of them.
You plan on using meth to protect the engine from total destruction :uh oh: Your new engine days are numbered taking that approach. Just a "hiccup" in the meth injection system, an empty reservoir or a clogged injector when you need it the most will have you writing big checks while learning a hard lesson. It's best to build an FI engine that can stand on it's own without outside help. I remember Kenny Bell posting on this topic and was very adamant about the dangers of relying on meth injection to keep an FI engine from self destructing.
At 10:1 I would turn the boost down to 8 psi to minimize the chance of blowing a very expensive engine.
And how is a 03-04 cobra motor at 8.5-1 with a 2.9 or bigger running 22+ psi any different. Maybe my comparison on the numbers isnt exact but the concept is
If he's relying on meth to keep his engine from exploding there is no difference other than the level of destruction.
At 22+ psi those guys run E85 or race gas.
I have posted this diagram here before but I thought I would show it on this thread to illustrate the difference in what the combustion chamber sees "high compression vs. low compression" on an FI engine. It's a bit exaggerated regarding the numbers but that was done to make it easier to understand. The physics never change though. This should clear things up for some who didn't have a clear understanding on what's involved.
Who created that? This is a pet peeve of mine, the "then" should be a "than."
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