nah22accord

Just what the topic says?

TurboTeG4

Why high compression, doesnt make sense

PyroProblem

Im not exactly sure what your asking but Ill try and answer it anyways.....6

nah22accord

I have a motor that is pretty much fully built.
H22a
GE sleeved and built with JE 11.5:1 compression pistons and eagle rods
Head ported polished and built by portflow
Skunk 2 stage 2 cams
255lph fuel pump
550cc RC injectors
Hondata s300
Nitrous

I was mainly building it as all-motor but recently came upon a turbo kit my friend has for cheap. Just wanted to know what yall think of this.

TurboTeG4

Nah turbos are for low compression, im sure you could run it but it be risky, too risky in my opinion for a high dollar engine.

SiKid86

Your turbo will spool faster with higher compression. It can be done just tune tune tune make sure its tuned VERY well and you always run 93 or the highest you got.

Schister66

would it make sense to get a bigger turbo like an SC61 or something bigger and run low booost?? It would spool quicker and basically just add to the top end.......not a lot of boost pressure, but more
airflow....

TurboTeG4

But in the long run ur ALWAYS goin to want to step up the boost

teamitr

Don't do it!.
First find out what compression inside your cylinder does. Then think about it again. That is why turbos are ment for low compression motors. plus low compression motors make more power with less boost then high compression. (because the lower the compression the more compressed air can fit in the cylinder, and more air with more fuel= bigger combustion.)

njn63

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by teamitr &raquo;</TD></TR><TR><TD CLASS="quote">Don't do it!.
First find out what compression inside your cylinder does. Then think about it again. That is why turbos are ment for low compression motors. plus low compression motors make more power with less boost then high compression. (because the lower the compression the more compressed air can fit in the cylinder, and more air with more fuel= bigger combustion.)</TD></TR></TABLE>

pretty much everything you just said there is wrong.
1. A high compression motor would make more power with less boost. Not the other way around.
2. Compression has nothing to do with how much air you can fit in a cylinder.

Maybe you should find out what compression inside your cylinder does...

raceACCORDingly

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by teamitr &raquo;</TD></TR><TR><TD CLASS="quote">Don't do it!.
plus low compression motors make more power with less boost then high compression. (because the lower the compression the more compressed air can fit in the cylinder, and more air with more fuel= bigger combustion.)</TD></TR></TABLE>

wow

wickedEG

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nah22accord &raquo;</TD></TR><TR><TD CLASS="quote">I have a motor that is pretty much fully built.
H22a
GE sleeved and built with JE 11.5:1 compression pistons and eagle rods
Head ported polished and built by portflow
Skunk 2 stage 2 cams
255lph fuel pump
550cc RC injectors
Hondata s300
Nitrous

I was mainly building it as all-motor but recently came upon a turbo kit my friend has for cheap. Just wanted to know what yall think of this. </TD></TR></TABLE>11.5:1 might be a little to much plus they are dome pistons that were not designed for boost. If this is a daily driven car it won't last. My new motor is 10.2:1 with a big GT70 turbo but that's meant mainly for the track. If you want to do high comp I wouldn't do more then 10.5:1. if you what is to last and if you do tune, tune, tune!!!!!!!

beepy

I think it could be done with the same fuel you would use N/A. It's just a matter of cooling the IAT's back down. You might end up dependant on meth/water injection. But if it's a race car...

b16hybridsol

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by teamitr &raquo;</TD></TR><TR><TD CLASS="quote">Don't do it!.
First find out what compression inside your cylinder does. Then think about it again. That is why turbos are ment for low compression motors. plus low compression motors make more power with less boost then high compression. (because the lower the compression the more compressed air can fit in the cylinder, and more air with more fuel= bigger combustion.)</TD></TR></TABLE>

hah whats the deal with people making their own theories lately

Cprace1

10.5:1 LS Vtec here on 9 psi the car did 300hp with higher compression you need a good tune and of course on higher boost levels higher octane. I would not say go crazy with the compression but a little higher than normal is not a bad thing with a good tune.

boosted92

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SiKid86 &raquo;</TD></TR><TR><TD CLASS="quote">Your turbo will spool faster with higher compression. It can be done just tune tune tune make sure its tuned VERY well and you always run 93 or the highest you got.</TD></TR></TABLE>

Jeff Evans posted a comparison of 9:1 and 10:1 and showed high compression didn't spool the turbo any quicker, but what would he know anyways.

I've owned a few turbo hondas and am currently daily driving a car with a 9:1 GSR motor and I feel anyone who says that your car is going to feel sluggish at 9:1 is feeding you a load of BS.

Cprace1

I've owned a few turbo hondas and am currently daily driving a car with a 9:1 GSR motor and I feel anyone who says that your car is going to feel sluggish at 9:1 is feeding you a load of BS.[/QUOTE]

Agreed 9:1 is pretty healthy for a turbo car

b16hybridsol

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted92 &raquo;</TD></TR><TR><TD CLASS="quote">

Jeff Evans posted a comparison of 9:1 and 10:1 and showed high compression didn't spool the turbo any quicker, but what would he know anyways.

I've owned a few turbo hondas and am currently daily driving a car with a 9:1 GSR motor and I feel anyone who says that your car is going to feel sluggish at 9:1 is feeding you a load of BS.</TD></TR></TABLE>

that comparison wasn't exactlly right tho because the high comp. motor was a stock gsr motor and the 9:1 motor was a built bottom end with a slightly larger bore, after market pistons etc....

blocburner1

Well i have a B16a3 stock (accept for a decked head) in a EG coupe with a garrett 67 trim pushing 10.6 psi and have not had a problem yet (two months in to it). Im getting a full Rev valve train because my head isnt pulling any vacuum. hopefully all will continue to be good. i know a few guys pushing 10.5 and up that have not had any problems it all depends on ur tune.

.nate

Slap a cometic .054" Headgasket on there. That will drop your compression to around 10.7:1 - a much safer compression ratio for a turbo street car.

The skunk 2 stg 2 cams may be too much overlap, maybe playing with the cam gear settings on the dyno could help...

boosted92

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">

that comparison wasn't exactlly right tho because the high comp. motor was a stock gsr motor and the 9:1 motor was a built bottom end with a slightly larger bore, after market pistons etc....</TD></TR></TABLE>

And if 22CC's makes up the difference in spool that a full point in compression gives you, that obviously has to tell you something about how much compression effects spool, doesn't it.

b16hybridsol

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted92 &raquo;</TD></TR><TR><TD CLASS="quote">

And if 22CC's makes up the difference in spool that a full point in compression gives you, that obviously has to tell you something about how much compression effects spool, doesn't it.</TD></TR></TABLE>

think a little more indepth about things such as the flame front traveling on a flat face and raised face piston, also the texture of the piston face, the silicon contents of the pistons. and if a little displacement gains don't help why are 90% of the b series guys at least steping up to 1.9?

also milage on the shortblocks ring seal plays a huge deal in combustion pressures etc.. so which would have a better seal a mid milage gsr motor (i believe it had like 60k or so) or a freshly built and broke in shortblock?

little **** doesn't matter by itself, but numerous little things that play a role in the same task add up

boosted92

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">

think a little more indepth about things such as the flame front traveling on a flat face and raised face piston, also the texture of the piston face, the silicon contents of the pistons. and if a little displacement gains don't help why are 90% of the b series guys at least steping up to 1.9?

also milage on the shortblocks ring seal plays a huge deal in combustion pressures etc.. so which would have a better seal a mid milage gsr motor (i believe it had like 60k or so) or a freshly built and broke in shortblock?

little **** doesn't matter by itself, but numerous little things that play a role in the same task add up

</TD></TR></TABLE>

When you start talking about flame fronts and how the material of a piston effects how a turbo spools, you're looking at things way too minutely related. The ring seal is the only thing that could make a difference IMHO, but if the motor went by the typical 5% power gain/loss for a full point in compression formula (which it did) then I think it's safe to assume the motor had good leakdown/compression numbers. I went from 81.5mm bore to 84.5mm bore on my old PT67 P-trim setup in my hatch and got about 500 RPM's quicker spool, so if that gain is static with change in displacement you're looking at about 50 RPM's quicker spool with the displacement gain from boring the motor .5mm over.

Sure, Jeff's test is far from perfect, but it's the best anyone has done so far. That paired up with my personal knowledge as well as what a lot of other experienced tuners on this board tell me is enough for me to say that compression ratio has, at best, a very minute impact on how a turbo spools. I'd just as soon spend extra cash on something proven like a ball bearing turbo or better cams to help boost low/mid range power, rather than try and bandwagon it with compression.

InfamousDC2FI

isnt the whole point of running lower compression pistons to PREVENT dentonation??

njn63

i think people aren't looking at the high compression the right way.

It might not spool a turbo that much quicker, but the car will get to the RPM where the turbo is spooled quicker. This kind of thing is impossible to tell from a dyno graph.