It's not comparable, that's what we're saying.
The popular turbo for Hondas at the time was the "disco potato". No clue what the specs were. I ran a Precision SC ..34, I think? Man...been so long.. I don't remember those specs either. It was a rather large turbo, though, to move enough air.
I believe the final tune had me at 10psi.
You don't notice much lag when you only need 10psi

11:1 + vtec + Honda VE + a bit of boost on the top end = soooo much fun.

 

needing methanol injection to make 350hp sounds like a hoot.

Seriously though the 4g63 is engineered for turbocharging. You play to your strengths not your weaknesses. You want more power, cram more air down its throat.

 

I forgot you know everything on this forum, if you don’t agree it must be false.

Thats the farthest thing from the truth it’s comical.

Clearly you aren’t going to throw 40psi at a pump gas motor regardless of compression, but running super low boost as mentioned by someone else isn’t the case either. You can find a happy balance, as long as you have a competent tuner.

 

With some cars, the peak number tells very little.

​​​​​

 

I know, I was just taking the ****.

 

I know.
a 2700lb car with instant 350whp and stupid responsiveness was a lot of fun, though.
p.S. If we had e85 back then? Mind...blown...

 

Just my .02 .

You can run low timing on a dyno run and get away with it on high compression/boost but the EGT's will go up. If you go out and beat on the car alot back to back it may not live that long. Look at a dyno graph with too little /too much timing at low smoothing and you get an idea how good or bad the engine is running.

9:1 for low boost on pump gas engine 18-20 psi or so (its just not worth running hard with better fuel out there IMO)
10:1 for an Ethanol /race gas engine
Lower then 9:1 for a max effort high boost engine that will last longer.

The best example I have is the TRC Evo. Its lower then 9:1 and its been run hard for a decade with over 15K of HARD miles. Lower compression lets you run more timing,less EGT's and its less cylinder pressure. More room for safety . For decades OE and people that built engines ran low compression so things would live.

If I was building another engine I would 100% use a 94mm crank and 9:1 compression for moderate power.

 

Sorry to highjack your thread! I was actually about to start a thread on this subject.

I’m curious about running 8:1 or 8.5:1 compression for a large turbo, pump gas only engine. It seems that know one even offers off the shelf pistons in anything less than 9:1. I can see there probably isn’t much demand for them seeing most people are running E85 on high hp builds.

I live in Japan and we only have 93oct (98ron) available. I’m currently sourcing the components for my build and have been wondering about this.

I’ll be running a pp6870 T4 divided, trying to build as much safe HP as possible on 93. It would seem to me that going with 8:1 pistons I could push the boost higher, def not to e85 levels but 9:1 seems to be very limiting on pump. I would appreciate any input you guys might have.

 

Wiseco makes a few 8.6:1 options . You can also think about using meth to add some octane . Going to a larger crank will also help make more power since you are octane limited. The car will also drive better with more stroke.

 

Thanks for your input! I was considering a 94mm crank but also wondering about the 100mm. I’ve read a lot people having problems with the 100mm cranks breaking, this might be old news though.

 

What are "the best" pistons on the market for these cars for anything other than power? I have reasonable goals of 500-600whp which realistically any piston can handle, just not sure given the amount of options so more aiming towards consistency/quality/easiest to build, quietness, least oil consumption, etc (pretty much anything other than power I guess). All below are 2618 forging. Does not help my machinist has no preference lol. He's used everything apparently.

Do the piston weights matter?

Wiseco 1400HDs K626M86AP? 349g avg weight, cheapest/most common, proven option I guess.

https://www.extremepsi.com/store/Wis...II-and-IX.html

JE FSRs? 309g avg weight, cheapest. There's also JE Ultras but they're 10.0:1 comp and probably not off the shelf.

https://www.extremepsi.com/store/JE-...II-and-IX.html

Diamond 82005-4? 356g avg weight and has gas ports, moly coated skirts, and "forced pin oilers from the oil ring". 3-4 week order time (all custom not off the shelf). Had these in my motor and were okay.

https://www.realstreetperformance.co...-3cc-9-11.html

Manley Extreme (345g) or Turbo Tuff (375g) Pistons? Thickest wrist pins on the Turbo Tuffs @ .250in but also heaviest. Has gas ports on the Turbo Tuffs, all off the shelf (TurboTuff might be harder to get).

https://www.realstreetperformance.co...06310ce-4.html

https://www.realstreetperformance.co...-stroke-2.html

 

Any regularly-used, name brand piston is fine. Don't over think it.

 

For every 4psi you raise the comp by 1
eg: running 32 psi you are raising the comp by 8
9:1 comp jumps up to 17 comp at your peak 32 psi
10:1 at 28 psi = the same 17:1 comp that the eng creates
But high sc needs good fuel/gas

 

Although running higher compression, is indeed like running more boost and timing, there is a difference. Low octane and or low calorific value fuel, usually allows one to run high boost with reduced timing, but he will not be able to run the higher amount of timing he needs even if he reduces the boost. Adding timing makes the mixture much more prone to pre-ignition and detonation than adding boost.





Marios

 

A stroker crank has less material where you need it the larger you go. A 100mm engine is also RPM limited so for a big turbo this won't work out well.

If 650-700whp is your goal and you aren't shaking the engine to death then a 100mm crank should be ok. 94mm is the choice for many.