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-   Custom Dodge Ram Performance Mods - Engine - 5.7 HEMI V8 (http://www.ramforumz.com/forumdisplay.php?f=83)
-   -   For engine builders, bump compression? (http://www.ramforumz.com/showthread.php?t=146408)

S.C. Express 06-30-2013 04:33 PM

For engine builders, bump compression?
 
Would it be possible/affordable to bump our 4th gen Hemi's from 9.4:1 up to 10.4:1? Reason I ask is my last car had a 2.5L 4 cyl. VVT engine built from the factory with 10.4:1 compression. It ran 87 octane fine, in fact it was factory recomended! It ran just like our 4th gen hemis do as far as where the power was and how they pull like crazy after 3500rpms or so...It was the first thing I noticed when I test drove my new Ram, how the engines performed almost identically! Except for 1/2 the h.p of course. Just a thought I have had for a while, I was wondering if the block or heads could be decked a bit for a little more compression?

RAM EM 06-30-2013 05:05 PM

I would imagine you would run into some serious knock issues with our engines, especially when trying to run more aggressive timing maps. They seem to be running at the edge of detonation as is w/ just a mild tune. It probably could be done, but it would take some careful machining, blueprinting, and tuning. Then it would probably be necessary to run 93. IMO, it wouldn't be worth the minimal gain in HP. Maybe for a dedicated race engine. JMO.

RamTex 07-01-2013 12:17 PM

Stock compression ratio should not be that low thicker head gaskets should drop it to around 10:1... Stock cr is around 11:1. Unless you are going forced induction dont drop the CR...

CHVYKLR 07-01-2013 07:50 PM

the stock 4th gen HEMI has a 10.5:1 c/r

snrusnak 07-01-2013 09:02 PM

^like they said the CR is higher than you said. Going much higher than 10.5-11 to 1 and you need high octane fuel. The hemi already should be using 89 octane.

RAM EM 07-01-2013 10:19 PM

Quote:

Originally Posted by CHVYKLR (Post 1139686)
the stock 4th gen HEMI has a 10.5:1 c/r

That makes more sense. I thought 9:4 sounded kinda low, just wasn't sure.

RamTex 07-02-2013 11:58 AM

Quote:

Originally Posted by CHVYKLR (Post 1139686)
the stock 4th gen HEMI has a 10.5:1 c/r

I was close... New it wasent 9.5 or w/e

S.C. Express 07-08-2013 04:19 PM

Nevermind then, thanks guys. For some reason I had 9.4:1 stuck in my head. Glad I was wrong. 10.5:1 is plenty high enough.

CHVYKLR 07-08-2013 07:05 PM

check out this gas motor with a 14:1 c/r on 91 octane pump gas. crazy looking pistons.

http://www.mazda.com/mazdaspirit/sky...kyactiv-g.html
http://www.caranddriver.com/news/maz...d-engines-news

bucks 07-09-2013 11:38 PM

Quote:

Originally Posted by CHVYKLR (Post 1145067)
check out this gas motor with a 14:1 c/r on 91 octane pump gas. crazy looking pistons.

http://www.mazda.com/mazdaspirit/sky...kyactiv-g.html
http://www.caranddriver.com/news/maz...d-engines-news

That's some pretty impressive technology in this thing. Makes me excited to see future engines.


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