I just bought a set of flat top 9.8:1 compression CP pistons off of a local guy, they were a very good price and NIB. I have a GSR motor, I am going to put eagle rods in it, hopefully with these pistons, and my turbo setup I am compiling. I have a Precision GT35E turbo, SFP manifold, 3" downpipe, and a precision intercooler for my turbo setup. It is going to be tuned using Hondata S200. My goal is to make around 430 WHP on 92 octane pump gas. Do you think the 9.8:1 compression is too high? I did a lot of searching on here, and found lots of people advocating high compression turbo setups due to their increased off boost response, but I am begining to wonder if I made the right choice buying these 9.8:1 pistons. I see some people running 12 pounds of boost on an 11.5:1 motor on 94 octane, others running 16-17 pounds of boost on 10.5:1 with 93 octane, and I figure I should be safe, but am I?

 

I run 92 octane with CP 9.7:1 Compression pistons no problem. All about the tune and how much power your making per psi.

 

what he said.. It's just alot easier to tune a Low CP motor.

 

9.8 isn't that high. look at all the peeps running 10+ compression and making really good numbers. we're building a 9.8:1 gsr motor for a customer right now using JE's, eagles, uberdata and possibly a Full-race kit. well see how that turns out.

 

But all the people running 10:1+ compression get 93 octane or better. We get 92 at a select few stations, but most do get 91, so there are going to be some times when I will probably have to get 91 octane. I just want to see somebody else making the kind of numbers I want to make on 91 octane, if not I'm going to sell or trade the 9.8:1 pistons for 9:1 pistons.

 

what are your power goals? what are you going to do for manangement? how well are you going to tune the car?

Answer those questions, and we can help you much better.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar &raquo;</TD></TR><TR><TD CLASS="quote">what are your power goals? what are you going to do for manangement? how well are you going to tune the car?

Answer those questions, and we can help you much better.</TD></TR></TABLE>

I already answered 2 out of the 3. I am shooting for around 430 WHP on pump gas, I have hondata, and it is going to be tuned well. More than likely going to Torquefreaks/Horsepower freaks in Washington.

 

Sorry I spaced out. Should have read most of that. I'm going to ASSume that whoever is tuning it is competent. This isn't always a good assumption, but I'm not a hater by nature.

drop your compression lower without any doubt.

I wouldn't try to make more than 400whp on a stock head with 93 octane unless it had cams and valvetrain, but then again I'm very conservative particularly when tuning other people's cars.

430 on race gas with that setup would be cake.

If you didn't want to get new pistons, I'd recommend valvetrain (so you can spin it faster - faster = more HP), cams (more cam = more airflow, more airflow = more power before bad things happen), portwork (can't hurt) instead.

 

Whoops, posted on my room mates account there by mistake.

I have ITR cams, a very mild port job (basically just a gasket match and cleaned up the ports), and I do plan on new springs/retainers. I also heard from lots of people to ditch my ITR cams for GSR cams because overlap is bad, but there seems to be a lot of misinformation spread around here. ****, I was even going to trade my GSR trans for an LS trans because I heard on here that longer gearing is better for turbos, before I did more research on it. I digress. When I stop and think about it, I can probably sell the pistons for more than I bought them for, make a bit of profit, and buy a set of 9:1 pistons. I really don't have much if anything to gain by running 9.8:1, but a lot to lose.......

 

Keep the ITR cams IMHO. If anything, get a set of cam gears.

How ballsy are you? How long do you want this motor to last? How close to the edge do you want it tuned?

ITR cams, mild portwork, those pistons and I could see 350-375whp on pump gas without pushing the limits of that motor. You'll gain much better off-boost drivability, throttle response and spool time with those pistons.

I'd just be a little scared about trying to break 400whp with the compression that high on 92. Just don't think it will happen.

 

that is how my motor is built....
Still waitin for engine management though cuz that fmu aint gonna cut it.

 

I have been running around 9.8/9.7 compression on my t3/to4e at 10 pounds constant daily driven not one problem just had the gt35e installed and it is going to be tuned to 18psi (for precaution purposes only) I am very conservative when it comes to my motor you dont have to be a hell on wheels everytime you get in your car, my honest opinion 9.5-9.8 is perfect compression in a 1.8 liter for the size turbo that you are running, also from what Jay from SSE TEK always says "its all in the tune".

 

your compression level of 9.8 :1 is not a problem at all. But aiming for 430 whp probably isnt the best thing for longevity. On a 10:1 setup properly tuned 375 whp is a safer goal. Of course everyone has a different opinion. My setup is 9.8 :1 also but to make anything over 400 whp i will switch to race gas and do it the right way.

chris

 

I would agree with above. It's all about the tune and how you drive. I don't get on my car every chance I get. I've been running 10.5.1 stock compression and stock internals for a lil over a year in a half without any problems and I have had three different turbo set ups.

 

Well as soon as I get cash for engine management my motor will see about 15psi pump gas

 

Uberdata
Crome
Come on now, decent number of 300+ cars and even a few 400+ cars running around on it... If money's the issue, DIY and be done with it.

 

https://honda-tech.com/zerothread?id=1030474 Answer your question

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar &raquo;</TD></TR><TR><TD CLASS="quote">Uberdata
Crome
Come on now, decent number of 300+ cars and even a few 400+ cars running around on it... If money's the issue, DIY and be done with it. </TD></TR></TABLE>

Is crome stable. I thought the ignition table was off or something like that?