I have been hunting through older threads, but I thought I would ask what is the more modern view on compression ratios? The newest stuff I have been finding is a few years old and I know the world moves on quickly with this stuff.

I kind of inherited an evo 9 engine with 10.5:1, guy was using it for drag racing and using a larger turbo 6266.

I was going to repurpose it and go to more track and hillclimb kind of stuff and use a stock frame Blouch 2.0XTR (BBK-B) and try to go flex fuel (compete on e85 and drive it home/store it on 93.) So, I guess my big question is, should I send this motor out and redo it and have pistons swapped (or swap em myself) or is this a reasonable CR for a stock frame unit pushing 30psi or less.

Thank you all for your time.

 

It's already built, so just run it. But I wouldn't run boost on 93 octane with the compression. And on E85, you'll be running less timing than a 9:1 motor to keep it happy.

 

Yeah, if its on 93 its literally to go home or drive somewhere if i can't get e85, not for all the horsepower. and I think with the turbo I have it has a max of 32ish real practical level is 27-28 it seems. Like I said car isnt assembled yet so we are at the final jump off before changes get more irritating.

 

yea, since its done I'd definitely run it. I have a built 10.5:1 motor with an FP Red(similar in size to the Blouch 2.0XTR I think) and it is great. I have a flexfuel setup as well so its a pretty comparable setup. On 91, I run gate pressure and basically no timing and then crank it up on E85(35-37psi). I have been running this setup for 3+ years at this point without issue minus 1 head gasket that was likely poorly torqued headstuds.

 

Alright then, and as a sidebar, what kind of cams are you running in your set up? I'd love to his somewhere near your kind of output.

 

So my full setup is a built 10.5:1 2.0 with L19 studs, MHI FP Red, ID1700x, double pumper with 2x 255s, GSC S2s, GSC Beehives, ETS intercooler and short route piping, Synapse DV, Yaris coil on plug setup and Stock intake and exhaust manifolds.
Car makes excellent power on E85 and is basically a camry on 91 lol.

My original setup was a Green on the stock motor and when I had a timing tensioner fail, I build it to replicate that power band but with about 100more peak horses. Car makes about 30psi at 4200 rpm and holds til about 7000 before the MHI exhaust housing and stock manifold cause some drop to about 28psi at 8000rpm.

All this said, my setup is a street car with some drag/roll racing here and there. For a track car, I'd suggest not running the turbo quite this hard to keep everything together.

Let me know if you have any more questions man, glad to help out.

 

Yeah, the plan was to go get it on the dyno and have i tuned then take it to 8-9/10 to keep it alive for what i do. next motor i may do a bit differently. thank you, it looks like your set up is almost identical to what im doing, I may have a little more intake and exhaust flow mods going, and a ridiculously ported head but not sure if thatll help. But, I may reach out to pick the ol brain in the future here as i put finishing touches before heading to the tuner.

 

I agree with Sean.

High Compression is harder on things . Tuning and good fuel should be on point.

 

I ran 33+ psi with a GTX35r on a 10:1 forged motor using Shell 93 pump for ~60K+ miles with no issues. If you're gonna choke the turbine side with a BBK then it will become more knock prone and you'll have to lower the boost and timing accordingly.

 

I honestly don't know how that's possible without octane or meth injection. I personally wouldn't run an engine hard on pump gas over low spring pressure.

Was that a single pull or could you do a few back to back 1-4 rips? Something will make a number for one pull, but its backing it up or having a margin of safety that most want to live with.

Did you have large cams?

Any chance the pistons were the wrong part number and were 9:1. Regardless, over 25psi on pump isn't something I'd recommend.

 

3* of timing at 8k... wooooo

 

It was Curt Brown's 10:1 short block from his blue EVO that I purchased many years back. It was a daily driver so I beat on it all the time and really enjoyed how well it ripped to 9K rpm with the S2 cams. I would do 1-4 gear pulls mid summer with no issues. Not to say there was never occasional knock, but for the most part the setup was knock free and I ran it for about 64K miles before pulling it for the stroker motor.

I was running 8deg @ 8K rpm on the 35r, but if I had a cute little 30r turbo I would definitely have to run less.

 

Thats wild.

 

I had to dig up the info from Curt's old email to me, but it used the JE Asymetric FSR Forged Piston kit (2.0L, 10:1). The 62mm turbine exducer helped, but the Garrett 24x12x3.5" always keeps temps within 20F of ambient and I also run 3.5' exhaust. Knowing what I do I should have run the same S362 (6268) that a I do now with a small runner equal length TS setup. Just can't deny the benefits of turbine efficiency.

 

IAT is one thing but cylinder pressure is another. You got away with it for a long time. Kudos to you Sir.

I just want to warn others that its not common practice to run all the boost on pump gas,high compression and get away with it.

Many years ago a few people starting targeting 19* out the top with whatever turbo they could. Others followed .. The results were alot of heavy trophies and thousands of dollars.