Why don't people run low compression, like 8:1 on a honda motor. I know there is a loss in spool time and low end power, but if i cared about low end power i wouldn't own a honda, let alone with a turbo on it. I dont want this thread to get into an arugment over which you can make more power on, it has been proven that on pump gas you make more peak whp with lower compression motors. I know a lot of people like the feel of their 10.5:1 compression motor, but I want to make some crazy power, and go with a compression ratio in the range of 7.7 to 8.3.

Any comments why or why not this would be a good idea. Also, has anybody tried this low of compression on a honda motor?

 

i run 8:1

 

almost as low as my DSm..lol...stock is 7.8:1

 

8.1 compression here....

 

How do you guys like the low compression?

 

I say run like 9:1 . I feel its a happy medium and can make amazing power on pump gas. 7s is waaaay to low IMO . 9:1 and 18lbs on pump gas and you'll make plenty of power, have decent spool, decent low end.

 

Do companies stock 8 to 1 compression pistons for honda's, or are thet special order? I know when I ordered my cp's the sales rep at race engineering asked if I wanted 9 to 1 or something in the 10.5 area.

 

There is no need to run 7.7:1 in a honda when on 9:1 you can run 20 pounds of boost on 93 octane, and make more power than you can ever hope to hold on the street. At the strip just dump in some race gas.

 

They are special order from CP, and I assume every other company. I wan't to run with bikes from a roll so I need to make some mad power. 20lbs on 9:1 is almost enough, i've ran 16lbs on 9.2:1 and I definitly need more. A ~110mph trap speed isn't going to win many important street races.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cyphear &raquo;</TD></TR><TR><TD CLASS="quote">They are special order from CP, and I assume every other company. I wan't to run with bikes from a roll so I need to make some mad power. 20lbs on 9:1 is almost enough, i've ran 16lbs on 9.2:1 and I definitly need more. A ~110mph trap speed isn't going to win many important street races.</TD></TR></TABLE>

if youre only trapping 110 with 16lbs on a 9.2:1 b series with a decent setup, then somethings not right

 

we'll, one its in an integra... I was trapping 105 @ ~11psi, so i think 110 @ 16 psi is about right.

EDIT: after some searching, it looks like 280WHP is right for 110 trap speed. Which is about what I would make at 16psi.

 

its going to be hard to beat a bike with an integra. im going to be about 400whp on pump in my &lt;2000lb hatch and am not expecting to beat bikes(750 or bigger for sure)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Casey &raquo;</TD></TR><TR><TD CLASS="quote">its going to be hard to beat a bike with an integra. </TD></TR></TABLE>

Thats why I want to do it.

Yeah, i dont plan on taking anything over a 600.

 

Most new 600CC bikes are trapping in the high 120 low 130 MPH range. A civic trapping 130 will do most any new 600CC bike ugly on the highway. My car made 433 WHP on low boost/pumpgas weighs in at a pinch over 2400 with driver in a mostly full interior EG, and it traps 110 in the EIGHTH mile. That equates to around 135 in the quarter, and I have ran brand new 600's on the highway and they havn't fared to good. You don't need 7:1 compression to run with bikes. Go with 9:1 compression, slap on a GT35, and have fun with it.

 

What compression did you make 433WHP on pump gas with? any other key parts to the 433whp pump gas setup?

 

- I know this post is related to turbo compression, But i just got a quick question.
I'm about to get my motor built, but I'm kind of confused about what compression to go with. I talk to some shop and the first thing they always say, " If you got 2 power adders - 9.1 , if you got only one 9.8". Well, but that goes for a turbo.. I know I'm not gonna make alot of power with my JRSC, But I wanna be able to make a good amout of HP. I know that alot of fast turbo cars are now going with 10.1 - 12.1 to make more power at a lower boost...
What would you guys recomend me if I wanna go 14psi in my JRSC, I'm thinking 11.5 or 12.1 ?
thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RuffGsR &raquo;</TD></TR><TR><TD CLASS="quote">- I know this post is related to turbo compression, But i just got a quick question.
I'm about to get my motor built, but I'm kind of confused about what compression to go with. I talk to some shop and the first thing they always say, " If you got 2 power adders - 9.1 , if you got only one 9.8". Well, but that goes for a turbo.. I know I'm not gonna make alot of power with my JRSC, But I wanna be able to make a good amout of HP. I know that alot of fast turbo cars are now going with 10.1 - 12.1 to make more power at a lower boost...
What would you guys recomend me if I wanna go 14psi in my JRSC, I'm thinking 11.5 or 12.1 ?
thanks</TD></TR></TABLE>

I dont like that "power adders" thing. I'd say if you want to run 14psi on pump gas you are going to need between 9 and 9.5:1 compression to avoid detonation. I'm NOT speaking from experience, hence the reason of this post, but I really recoomend you go with lower compression.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cyphear &raquo;</TD></TR><TR><TD CLASS="quote">What compression did you make 433WHP on pump gas with? any other key parts to the 433whp pump gas setup?</TD></TR></TABLE>

84mm sleeved GSR motor with 9.5:1 compression custom JE's and billet crower rods, lots of other work done. Turbo setup is a PT67 P-trim with the anti-surge compressor cover and a .68 A/R tang exhaust on an inlinepro manifold with a 40MM tial, 3.5" downpipe to full 3.5" exhaust, PTE cooler and home made charge pipes. When it made 433 I had a boost leak, so while the boost gauge t'ed off the compressor cover said 17 psi it was actually leaking down to around 12 or so.

RuffGSR: Unless your car likes a steady diet of race gas, you don't stand a hope in hell of making good power on 11.5:1 compression with a non intercooled roots blower. They're the most inefficient power adder to begin with, and having no intercooler only makes this problem worse. The power you're going to make with 11.5:1 vs. 9:1 might be 10-15 horsepower off boost. If you want to try and run pump gas with 11.5:1 and lots of boost you're going to need to pull out a **** load of timing and add in a **** load of fuel, and you will make less power with 11.5:1 and pump gas than you will with 9:1.

 

B18B1~84mm 8:1 compression here ,,,love it....Need new Race mani though

 

my vw/audi 20v is 8:1... should be scarry fast @ 25+ psi in a sub 2000lb mk2 gti.

low compression nothing is more frustrating then having to pull a shitload of timing or run 8 dollar a gallon fuel.

 

I like all your replys! Not what i expected. I thought a bunch of people would be against it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cyphear &raquo;</TD></TR><TR><TD CLASS="quote">we'll, one its in an integra... I was trapping 105 @ ~11psi, so i think 110 @ 16 psi is about right.

EDIT: after some searching, it looks like 280WHP is right for 110 trap speed. Which is about what I would make at 16psi.</TD></TR></TABLE>

o_O my buddy made 205hp at 5psi on a small *** 14b on a stock block GSR motor
Seems like you'de make a lot more than 280 at 16psi especially with a correctly sized turbo.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cyphear &raquo;</TD></TR><TR><TD CLASS="quote">we'll, one its in an integra... I was trapping 105 @ ~11psi, so i think 110 @ 16 psi is about right.

EDIT: after some searching, it looks like 280WHP is right for 110 trap speed. Which is about what I would make at 16psi.</TD></TR></TABLE>

What turbo are you running? What engine management??

No offense, but those speeds/power levels are weak for the amount of boost you are running.

 

i was looking in to wiesco.. cause they have 8.5 to 1 pistons... cuase i was thinking about juicen with the boost...

 

No offense taken. That WHP estimate is just an estimate. Its a bone stock B18B with a conservative uberdata tune. I haven't had it dynoed and when I went to the track my damn profec B was being gay and going WHOOSHH...WHOOOSHH... so i'd boost between like 9psi and 16psi the whole way down the track... then i finally got it figured out i think (turned the gain down to 0), and one of my friggin sleeves went out on me.

Long story short, i have no idea what my trap speed or my WHP is. I was just guesstimating to say that ~300whp and ~110mph traps isn't enough for me.