What's happening guys? I'm gonna start off by stating that this is a very long term build, with at least 2 years between now and completion.

This plan of my started with a bit of horrible luck, and a great deal on a set of forged 89mm 13.5:1 JEs.

The motor is a 94 h22a that decided to play patty-cake with a brand new set of DH-Racing "dome-top" valves. Go ahead and use this moment to make fun of me lol. I know it was a bad decision, and I've since accepted that and moved on. ANYWHO...

Money isn't really going to be an object, as it is impossible to take on this kind of adventure without some deep pockets.

I realize that with such a high CR, you're pretty much asking for trouble when you add boost to the mix. But hey, you only live once right?

With that said, my plan is to keep things as safe as possible, as I do not want to waste $3k or more in block building on something that could have been easily avoided.

Just wanted to see what everyone's thoughts on such a build might be. The highest CR I've seen on a boosted setup on H-T thus far, has been somewhere in the 11.5:1 area. Anything is possible with enough tuning and precaution, or so I've been lead to believe. Criticism is and will always be very welcomed. Let me know what you guys think. Thanks!

Also, if anyone is interested, I have plenty of pictures of the gnarly block carnage.

 

How much power are you looking to make, and what fuel do you plan on using?

If all else fails, you could always buy a new set of pistons.

 

PM Turbo-Charged or maybe he will chime in. I know he has talked about his 13.5:1 turbo setup before. Tempest Racing

 

I haven't really set a goal for power as of yet. I figure once the car is running a low amount of boost (5-6 psi) safely, I can then begin to turn up the boost in small increments and have some fun.

Realistically, I'd like to be at or around 500whp. If the block and all permits, I'd definitely like to see 700whp. But once again, I'm shooting for a more realistic 500whp as of now.

Nice! Thank you.

I can't explain how great it would be to have some experience chime in here. More the merrier. I will refrain from bothering people via PM this early in the game though. It's still a pipe dream right now. I have the car (still needs custom axles, and mounts), the block (unbuilt and needing head), the tranny (needs LSD), pistons, and a few other odds and ends right now.

This motor will be going into an '89 Prelude just in case anyone was interested or curious.

 

bump for an intersting build. Im currently running a 10:6.1 GSR setup and I LOVE the power out of boost, not sluggish at all like some 9:0.1 setups or less. 13 is high thought, definately get yourself a tuning appointment with someone who has experience with these type of setups, evans, tony, ect ect, that will be your best investment. Also, i doubt this car will be able to run on anything less than 110. maybe look into an e85 setup at worst, but she will certiantly not like 93 pump. anyway, good luck my friend.

 

Damn, thats high compression. Thought about all motor?

definately race gas only motor... you should send that head off to port flow and let them do it up, with some nice cams and valvetrain and a tune that thing should be gnarley!

 

Sorry I totally neglected the fuel question!

Yeah race gas might be the only option, or maybe lowering the f--- outta the CR via a stack oh head gaskets lol.

I'm not against E85 at all. I've heard some good things about it, at least for N/A builds anyway.

 

Why do you want to do this when you can make such great power with 9:1? It just seems easier and safer

 

this would be a great motor to run on alternative fuel...look into e85 (or straight ethanol)...methanol...alcohol....etc

 

Its totally doable with the right fuel/setup .. The better the whole setup the lower octane fuel you'll be able to get away with theoretically, but I don't see this happening on pump gas. You could probably make decent power with e85 before reaching the limits of the fuel but I don't think you'll reach 500.. Not saying its not possible, but its not very likely.. Now if you put it on Q16 then should be no problems making your desired power level. Go BIG on turbo exhaust housing, 4in outlet, T4, 1.20 A/R.. Spool won't be too much of an issue with that level of compression.

Good luck and let us know how it goes..

 

Check out this Evanstuning dyno test where the only change was compression ratio. It's interesting, almost nothing was gained in spoolup but power was higher once full boost was acheived. The most interesting part to me is how much more timing the engine wanted to make MBT.

http://forums.evans-tuning.com/viewt...hp?f=15&t=1612

 

I definitely agree on going big with the turbo. My idea was that the high CR would allow the car to have the initial response like an N/A beast, which would easily carry it into boost. Once you're in boost all hell should break loose. That's my theory anyway...

That is pretty interesting. I'm kinda shocked that going from 9:1 to 10:1 only yielded 15whp, which almost makes it not worth the risk.

One poster in that thread had a good point though; the small size of the turbo allows it spool quickly enough to negate the small bump in compression. Maybe?

 

Your right about the small turbo offsetting the change in power a bit, not going to take much to spool that reguardless of the compression. But if you read on evans explains that the change in compression does not correlate linearly with the power. So by simply increasing the compression you are not increasing the power at the same rate. As a result it makes more sense to run a lower compression motor and let the turbo get you to your desired power goals.

 

First of all, having a lower compression will almost always require more timing to reach MBT as the mixture is less dense therefore the flamefront speed will be lower, also .020 larger bore will also require a bit more timing to reach MBT cause the flamefront has a greater distance to travel... Yes only a small difference but good for a degree or 2.

Also The difference in compression I DO believe will have much less of an effect in this senerio due to the restrictive nature of the setup. In a less restrictive stup I think having a higher static CR will make a larger difference.. There is that point where gains from compression will start to fall off though. So if your fuel can support it, and your setup can support it, I think higher CR is the way to go on a RACE motor. Some motor/chamber designs just don't tolerate the higher static CRs so in those cases your better off with less compression so you can get more air and fuel in (forced) before knocking. While higher CR does make more power, theres a point at which gains from compression become outweighed by being able to stuff more boost in the cylinder safely. For the bestest most maxest power senerio there a perfect balance of boost and static CR that would probably take forever to figure out and only be valid for THAT specfic setup.

 

Well said.... (i prefer stock compression for all my builds...

 

Just quoting a post Turbo-Charged made in a thread...

With that said, it looks like good numbers on 13:1ish CR is fully possible. He doesn't mention fuel, so that's anyone's guess on what it's running.

But the key to what he said is less boost (and assuming less fuel), which as we all know is a good thing.

 

E85 and a combustion chamber/piston redesign are your answer.

 

I have never had the chance to tune a car with only the bore size changed. You really need a degree or two for half a mm overbore? Seems like that's a lot of timing change for a flame front that only has to travel a quarter mm extra in each direction. Is the travel speed very non-linear at the end of the burn or something. I assume you're talking about gasoline.