JDogg

here is a dyno comparison of an rsx s we just finished building

the first run (lower of the 2) was when the motor was bone stock with the turbo kit, the 2nd run was from after we replaced the pistons and rods with wiseco pistons/eagle rods. the pistons and rods were the only parts to change. the tune wasnt changed much at all, just to get afr right as a new turbo was going on so we didnt want to spend much time on the dyno. it was fully tuned on the stock engine.

this was about 7lbs of boost.



not sure what brand the turbo kit is... turbonetics or something, and we used the -9cc wiseco pistons, so its around 9:1 compression

thomas@LPS

the only thing i can think of is that the tune wasnt optimal on the stock motor like to much timing for a high compression motor. now that you at a lower compression the motor likes a little more timing.... idk seems weird...

nowtype

I'd take this down Jdogg. Something isn't right here. I'm guessing on the higher compression the computer was pulling timing because of minor detonation.

SuperTeg95

Could be loose bearing clearances and lighter rotating assembly freeing up horsepower.

dmotoguy

could the flatter pistons create a faster burn = more power?

JDogg

the computer wasnt pulling any timing.. the car had been running for over a year on the same tune and put down exactly the same power the day we pulled the motor as the day we tuned it.

ill stand behind what i say, with pump gas lower compression is better.

there were no timing changes, only a minior fuel adjustment (about 3%)

rorik

What about the effect of the new rings and cleanup hone too? (You didn't re use the stock rings, did you?)

I was having a little trouble reading the dyno chart, but it looks like the new combo makes less power out of boost and more once the turbo spools..that is really interesting and something new to me as far as that being a result of piston design..I've always figured the pistons are either going to make better or worse power across the entire graph.. obviously, with the exception being if you run into knock.

tmac007

Whats the new turbo that was put on it compared to the old one? Same replacement? or slightly different? If its different thats where the power came from.

rorik

he didn't want to spend much time on the dyno because a new turbo was going on in the future.

nowtype

Lower compression does not make more power given the same circumstances unless you are octane limited. End of story. This test goes against tested and proven theory. Sorry big guy, but your test has some flaw.

rorik

Lower compression could if the piston design is better, theoretically..
But what about the interesting thing here, the part of the graph under about 4200 rpm being lower.

fjt

Well if it serves of anything my lower compression motor wIth NO BOOST ran beter times than when it was higher CR..

YOu go figure....

I ran my car N/A before putting the pistons and it ran better times with lower CR pistons and closer to stock forms than when it had higher CR and more mods

JDogg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nowtype &raquo;</TD></TR><TR><TD CLASS="quote">Lower compression does not make more power given the same circumstances unless you are octane limited. End of story. This test goes against tested and proven theory. Sorry big guy, but your test has some flaw.</TD></TR></TABLE>

end of story nothing... my test has no flaws, it compares a perfect running stock 11:1 compression engine, and reduces it to a perfectly running 9:1 compression and omg it made more power.

im sure with some more tuning the low end could be made up, but we wont go with what could have been, we will go w/what the dyno says!!

nuclearhappines

This is an RSX right ?

you could be looking at computer adjusted valve timing ... hence the low end loss, high end gain, it looks like a cam adjustment trade off...

nowtype

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">

end of story nothing... my test has no flaws, it compares a perfect running stock 11:1 compression engine, and reduces it to a perfectly running 9:1 compression and omg it made more power.

im sure with some more tuning the low end could be made up, but we wont go with what could have been, we will go w/what the dyno says!!</TD></TR></TABLE>

Explain physically how lowering the compression allowed roughly a 20hp increase. Let's hear some tech to accompany your data.

bigbadboy

looks like somethings wrong with the stock tune. look how it breaks up right there in the middle. something is flawed

david@didrace.com

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nowtype &raquo;</TD></TR><TR><TD CLASS="quote">

Explain physically how lowering the compression allowed roughly a 20hp increase. Let's hear some tech to accompany your data.</TD></TR></TABLE>

Agreed. Just sounds like JDogg needs to do some more learning and gather empirical evidence. There are so many variables that could affect power it's not even funny. From the dyno not being calibrated, dyno bearings just lubed, a light next to the weather station heating up the ambient temperature and screwing with the correction factor, tolerances of the brand new motor compared to a motor with xx,xxx,xxx million miles, etc.

What a joke.

bdavis

IAT's, ambient temp, coolant temp, lunar cycle, etc.

This is one car dynoed in an uncontrolled enviornment

Way too many variables to prove this. You are gonna need more tests than this one with a jumping torque curve to prove what you think you are proving.

Sorry.....

JDogg

its 20 fn hp, you DONT have a 20hp change from a few variables in dyno conditions

and its obvious you havent used a dyno b/c there are no calibrations for dyno jet

david@didrace.com

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">its 20 fn hp, you DONT have a 20hp change from a few variables in dyno conditions

and its obvious you havent used a dyno b/c there are no calibrations for dyno jet</TD></TR></TABLE>

We use a Mustang dyno, which can be calibrated. That's one of a few dozen reasons why DynoJets suck.

I can tell you I've seen over 100whp change just from accidently having a spotlight pointed towards the dyno's weather meter (on a DynoJet btw ).

With no evidence to stand on besides some dyno numbers you might as well be trying to prove the earth is flat. Because it gosh darn sure looks like it's flat if you look at the horizon.


Modified by david@didrace.com at 4:45 PM 9/28/2007

bdavis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">
and its obvious you havent used a dyno </TD></TR></TABLE>

oohh wow. Engine calibration engineer here. I've spent a couple hours here and there on one. Hence I know your ONE test is null and void.

ProJectCvic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bdavis &raquo;</TD></TR><TR><TD CLASS="quote"> your ONE test is null and void. </TD></TR></TABLE>

I agree. I question your data.

JDMs1eeper

unless the stock pistons hurt the flame front and the combustion process (like CTR pistons). I don't see where lower compression would "gain" anything.

sc4dr

I know a lot of old school guys swear a lower compression motor makes for a higher hp boosted motor. Don't flame me, I've just heard it a lot, and I don't have any proven theories btw.

Chris Tune

i've seen this before... its piston design mostly. thats why some people flame the CTR's and say they dont make power, but a 8.25cc dome wiseco makes more power than an unfinished CTR. I've seen it many times and yes ctr's sucks in 100% stock form, with some work they are hard to beat for the price.

piston design wins it here OR if it was SAE corrected.. check if the corr didnt go from .98 to 1.10 or something, turbo cars tend to be more picky in that area.

PS: wow with smoothing on 5 and the graphs looks... not optimal clear that