Question on Power difference between high compression and low compression N/A engines
 

Pretty muchwhat the title says...What kind of Power difference is there between a high compression and a low compression N/A engine given the same displacement and H/C/I etc...
I've been wondering about it since I started driving my low compression turbo motor around...tomorrow IRS retting Dyno tuned but I'm still curious as to how big of a loss you take with compression issues. I'm guessing the difference between 8.8:1 and 11:1 is about 100hp.


Speaking if which, any guesses on tomorrow's results? Forged 370ci motor with high flow WCCH heads, 218/218 114LSA CAM and free flowing exhaust behind a 4l80e.

~380-400rwhp because of compression, cam, and 80e.

There's a formula but I forget, something like each .1 CR+ = X hp.

you are dyno tuning tomorrow?

394rwhp

I think it all depends on the cam and head combo...a high compression engine with a cam with a lot of overlap can run more timing than say a high compression with a small cam, as the engine with the smaller cam will be more prone to detonation. I believe that in most cases though, with all things being equal, and a camshaft of decent duration (somewhere in the middle of what's optimal for both high and low compression), high compression wins. I'm not an engine guru, this is just how I see it from what I've learned through the years.

not much help, but post your results. I may end up running mine NA for a while. Only thing is im stock heads, boost cam, 10.4 CR

I always thought of it a little differently but i may be way off...

A high CR engine with a High DCR would have timing limitations but make more power with less timing.... Because of the build up of heat caused by the CR and DCR it would be prone to detonation this is where higher octane comes into play. A low CR engine is more forgiving on the timing meaning it could run more because it would produce less heat thus less prone to detonation but it would make less power...

Well some of you guys sure optimistic!! :P
I'm guessing 320rwhp and that's being conservative so maybe it's more. In all fairness I've yet to actually do a full pull on the truck for various little things I've got to finish on it. Right now I'm headed down to put the Wilwood's back on and drill out the PCV so it will stop popping off...hope that drilling that valve will not create so much backpressure.
I will post up when I find out...

If you dyno 320 rwhp, you need to burn that thing to the ground...

1 pt is about 4%. so your down about 8-10% in power.

im sayin youll do at least 350 RWHP liked stated above if yoiu dont make at least that then something is wrong IMO

A point of comp is good for 3-5% in hp...

I wonder what comes between 3 and 5 :confused:

Yah I read it over after i posted it.. But guess it must be right since more then one of us posted up on it.. So you keep watching your movie you freak...

350-375 because of the 80e and small cam...

I dont think hes too worried about the numbers anyway. Its bee proven a high horse boosted motor

Yup yup! Not really worried what it makes to be honest, I know next spring it'll be in the 8xx hp range but right now trying out all these different combo's and seeing how they react is interesting!!

So assuming a normal stock compression 6L with all the bell's and whistles would make 400rwhp - 10% cuz of the low compression I'm looking at maybe 360rwhp...could be close! :nod: I'm still shooting for under 360rwhp though! :D

That could be very likely, considering I can't even be trusted to put a brake pad on the right way who knows what else I fucked up!! :confused: :barf:
The intake faces the firewall right? :burn:

What power adder are you going with?

:secret2: when I know more and that it will work I'll let you know, till then I still have more research to do.

*reaches for ban button* :P

Notice my signature!! :P

I'm gonna say 340ish

You need a D-1 and about 15 psi :D

learn to drive before cranking it up :P

This all makes sense...I guess it can be summed up as compression makes more power than timing (all things being equal and speaking generally and not technically). As always, the combo has to be perfectly matched or the point is mute...This sound right?

I try to think of it in terms of like cylinder pressure. But I dont think thats completely right. But the more pressure the more prone to detonate?

:barf::nunchuk:;)


Nice avatar too...

haha thats funny

Tvs2300??? or maybe a synergy twin turbo kit??? mucho boosto lol.

:jest: F#$&@ Mods and their edit button, I swear your a few crumbs short of an animal cracker Cody! :nono:

:shakinass:

Couple years ago John (xlrnss) got bored and started changing everybody's avatars and signatures to weird shit! :lol: Let's hope cody doesn't let his mod powers go to his head...Awwww too late! :(

You're just special sweetheart. Its a PITA to change sigs anyway, so for now you're the only victim, congratulations :kiss:

lol...

If Mucho boosto was an option that I pick that one! :)
Neither of the ones mentioned or any of the ones offered on this site...or any site honestly! :D

There goes Julien, has to be different inspite of himself :P

thats what ive always heard. for each full point gained in compression, you gain roungly 3 to 4% to your current power level.

spoolin, what the fuck is up with your avatar? which one is you?

Comes with the territory! I'm off to Justin's I'll tell him his former neighbor says hello! :wavey:

One of them is the Shamwow guy's twin brother who's on this site with us, and not sure who the other unlucky bastard is. Someone should tell the Shamwow guy to stay out of my user profile!! :judge:
:jest:

hold on...im guna make a guess on who the sham wow look alike is...

CODY!

if not, he could pull off the sham wow guy pretty good for halloween. just get him a headset!

I was wondering about that avatar too lol

ding ding ding!! :jest:
Yeah it's him, he's on a mission to express himself to this community via my avatar and sig! :rolleyes: