Tuning advances have changed things a lot (I'm searching but getting info from over a decade ago) and I'm not getting a consensus on what the best compression to go with nowadays in an Integra Type R motor when turbocharged on pump gas (Est 12-15 pounds). I used to run 9.0:1 pistons on 1 bar (just under 15 pounds of boost) in the old days, but I have been hearing people are running around 10:1 more often ) I've been out of the scene for a long time and going through the clutter on the internet is an endless outdated pile of information with the majority of people not knowing what they're talking about (as usual).

Sure you can run crazy compression on a fully built block, on E85 especially if you have the facilities and budget to rebuild your motor when ever you want, but this is a road car used as a semi daily driver. It will probably never see slicks and race gas or E85. This is strictly for 93 octane on the street and road courses, I'm building it to go around turns while being driving aggressively in high rpms and still be practical for a daily driver.

I personally don't want to invest in overly expensive build, my last build I dropped forged pistons in which is super easy an can be done on a Saturday if you know what your doing. I drove it hard regularly It lasted for years with no sleeves, just 9.0:1 pistons.

So is it worth the gain to go closer to 10:1, or stick around 9:1? I was trying to find a 9.5:1 piston, but so far I have only found 9.8:1 and 9.2:1.

Power goals are whatever I can make on 12-15 pounds on a .57 trim T3/T4, probably 350whp or something. Fuel management will probably be Hondata.
Also,if you happen to know, do the more aggressive cams of the type R have any impact, even if it's slight, on what compression will work best. The reason I ask is because hi compression pistons often work best with more aggressive cams in all motor application, although I'm sure how that works when force inducted. I've also noticed several Turbo Type R owners running slightly higher compression but that could be a coincidence.

Thanks,

 

Try posting this in the forced induction forum. You'll get better help there.

 

I recently had a GSR motor put together for my CRX, using off the shelf 9:1 Arias pistons. I used GSC T1 cams, edelbrock victor x manifold, a BBK 70mm TB, on a full race turbo kit using an EFR 6758 .85AR Vband. The size of the turbo is everything here. I sold the setup to a friend after purchasing my Type R, but he took me for a ride recently. We were doing 4th gear pulls from about 40-120, and the turbo was spooling at 24PSI literally instantly. There is ZERO lag with this turbo, and we were spinning tires the whole time, the car never hooked up. I used a 93 LS trans with an Mfactory 4.9 final drive, this put the gears identical to a US spec ITR, and a 12lbs flywheel.

If you can swing it, I'd recommend one of these EFR turbos. They make both the 6258 and 6758 in a T4 twinscroll .80AR now, and is probably the way to go, the transient response is insane, and like I said there is zero lag. The 6758 would have zero issue making 350whp, and your mid-range will be nuts.

I built this setup to run on pump gas, and 12-15 PSI just like you want to, and planned on making 330-350 on a tune made for shitty Alaska 90 octane pump gas.

 

My experience with boost and Honda's has always been with H series. I have always had higher compression and pump gas. I never had issues with either and drove them the exact way you described. The skunk2 pro series 1's had insane power gains on the H motors. Might be worth looking at those cams for a B series.

 

For the turbo size he has, Pro1s wouldn't do that well, unless he had over 61lbs/min. Unlike H series, B series had much better choices available for a true turbo camshaft other than a Pro1

 

The GSC T1 cams are one of the best cams on the market right now, and the baby EFR 6758 .85 handled them just fine. There is a thread on here somewhere with a guy making 40whp across his entire rev range with just these cams, using a PTE6262. 10:1 compression would probably be fine, it's becoming more common place like the OP said. I went with 9:1 because we only have 90 octane gas, but the higher compression will help you make your power goals with less boost, and help spool the turbo faster.

 

Yeah, the GSCs work with a much larger range of turbochargers than with the Pro1s. While the Pro1s work with only those that are 61lbs/min or above, the GSCs work with anything from about 45lbs/min to over 80lbs/min. Much nicer camshaft. But they don't do anything other than the Pro1 for the H-series.

 

This has been moved to the forced induction section. Thanks.