high compression & pump gas

[DensoSupra]

Does anybody know the highest compression I can safely run off 93 octane?

[edman24]

Originally Posted by DensoSupra

Does anybody know the highest compression I can safely run off 93 octane?

depends on your tuning but id say about 11.5:1 is getting pretty close. ive seen people run higher then that on 93 but thats with full engine management and knock sensors. i wouldnt push it any higher then that.

[B16EJ1]

11:5:1??? The suggested octane level on a stock B16B is 103 and that's just 10:8:1 so......

[DensoSupra]

Well I do know there are cars that come from the factory running higher then 11.5:1. Just an example, the F50 comes from the factory with 12:1 compression and still runs off pump gas...

This is may be *totally* different but my go-ped, running 13:1 compression, runs off 93 octane. I'm sure there is a big difference between a 25.4cc 2 stroke engine and a 1797cc 4 stroke but my go-ped still runs a 13:1 compression ratio on 93 octane with absolutely no knock.

I think I should just speak to a mechanic before I start ordering parts.

[edman24]

b16ej you need to understand the difference between suggested and doable. of course honda will tell you to only run 103 on the b16b but that does not mean it will not be safe on 93. i had an lsvtec motor, in case you dont remember, that was at about 11.2:1 compression running fine on 91 pump gas because thats the crap we get here in cali. a friend of mine tried pushing it with 12.3:1 but started pinging and blew the motor. so its up to you and your tuning basically.

[B16EJ1]

Yeah I remember your sweet ass hatch. But I figure that suggested is better than do-able, you know what I mean?

[DensoSupra]

Well I think I figured out what I'm gonna do. My friend knows this guy that has a hatch with a totally worked b18c. It makes 330hp and the guy has the dyno sheet to prove it. He runs 16:1 compression and just poors a bottle of octane booster into his tank before each fill up. 16:1 does sound a bit like overkill but he WAS making 330hp. I'm still going to talk to a mechanic before I go and do something crazy like that. It makes me happy because my horsepower goal is anything over 300hp.

[B16EJ1]

I'd like to know exactly how he pulled 16:1 off.

[DensoSupra]

Originally Posted by B16EJ1

I'd like to know exactly how he pulled 16:1 off.

The only reason I believe it is the dyno sheet. How many other 330hp b18's have you seen?

[94tegRS]

a bottle of octane booster is not going to make up for 16:1 compression, no way any car on the streets ever has that hgih of a cr.
you POSITIVE the dyno shet is of his car. maybe its his friends camaro with a small block V8 and he just says its his. Ive seen printoffs where it doesnt say what car, Im guessing this is the case here.

I talked to my neighbor once and he sounds like he knows his shit when it comes to engines and such, and he told me hed stay below 11.5:1 as well, but if it was him hed go with no higher than 11:1 just to not push it is how he said it. I went 11:1 but they are still in the box so I cant tell you how it worked out.

[DensoSupra]

Originally Posted by 94tegRS

a bottle of octane booster is not going to make up for 16:1 compression, no way any car on the streets ever has that hgih of a cr.
you POSITIVE the dyno shet is of his car. maybe its his friends camaro with a small block V8 and he just says its his. Ive seen printoffs where it doesnt say what car, Im guessing this is the case here.

I talked to my neighbor once and he sounds like he knows his shit when it comes to engines and such, and he told me hed stay below 11.5:1 as well, but if it was him hed go with no higher than 11:1 just to not push it is how he said it. I went 11:1 but they are still in the box so I cant tell you how it worked out.

No, I can't be positive that it was his car...I haven't even seen it. My friend does know the guy and has ridden in it. He did say it was fast as fucking hell.

As far as only going to 11:1, b18c5's come stock with 11:1 compression. Spoon b18c's come stock with 11.3:1 compression.

What kind of cars is your neighbor into? I'm saying this because I have even read that over 11:1 compression in a muscle car is dangerous because of their pos designs.

Well, like I said, before I spend a lot of money on 16:1 JE pistons, I'm going to talk to a mechanic.

[94tegRS]

well, a 330HP GSR would be, even a 230HP integra would be damn fast.
and maybe he means 330 at the crank which would lead to oh, say, 280 at the wheels, atainable NA, but still 16:1 aint gonna happen. maybe he puts in a half a tank of octane booster and then half a tank of race gas! I mean you wouldnt have to go that far I doubt, but no way on 93 octane with 1 bottle of octane booster would it work.

and he is into cars general, and not really cars, engines, he used to work in a shop where they did custom projects for people. hes also worked at a body shop, he has gone through school for boat maintanenece, has built lots of cars himself. 2 of those 4 dont even matter about this topic but just to show he is into cars/engines and that stuff.

and I didnt say 11 is maxed, he said he wouldnt go past 11.5:1 and if it was him hed stay at 11:1 because you wouldnt see a huge benefit over 11:1 and it wouldnt be a as reliable/easy to tune setup.


and thier pos design, sure their engines arent as hgih tech as todays, just 2 valves/cylinder pushrod type engines, but the rods bolt ot the crank, pisons on the rods, heads bolted to block, valves held shut with springs, piston moves up/down 2 times for 1 combustion, the basic "design" is the same with any internal combustion engine. so I am sure you can put a high cr in a old muscle car, probably just much easier on imports/newer cars, what do you think would be easier to tune with high cr, a new B18 with a ECU and tons of sensors and fuel injection or a 1960's small block 350 carbeurated?


and when you talk to your mechanic, youll see how right we all are.
on a B20, weak sleeved I know, 12.5 cracked this guys sleeves 2 times within like 500 miles each rebuild. so not only is it NOt going ot happen with pump gas, its not going to happen if you expect your engine to last longer than that one dyno pull that tels you you can make 330HP for 1 minute.

[Ricochet]

I run 93-94 on my B16B all the time. I can't find 103+ anywhere. I wonder what the hp difference will be?

[kittedb18bt]

my roommate has a '00 celica gts. their compression is 11.5-and he runs 93 octane. everything works out fine.

[jcrx]

Originally Posted by DensoSupra

He runs 16:1 compression and just poors a bottle of octane booster into his tank before each fill up.

BULL-FUCKING-SHIT. There is NO way to run pump gas, even 100 octane with a 16.1:1 C/R. Period. And where did he get 330? from a dyno, no, not unless he had maybe a dynopack/rotortest and even then, I HIGHLY doubt it, since the readings would be at the wheels, and then you go on to guesstimate the whp, other than that he is pulling your chain.

one bottle of octane boost (biggest scam on the market) = about .01 octane level. So you take one bottle and add it to your 93 octane and you get 93.01. It's a complete waste. Don't go higher than 12.1:1. A buddy ran 12.?:1 on pump in a fully built b20vtec, and it ran fine, but it was tuned.