boost on 10.5:1

[94tegRS]

ok, I have 11:1 JE's in my B20 now but on my next car I will probably go B20 again and boost it next time around. I had to pay quite a bit extra to get my pistons custom machined to 11:1 and I see they have 9.0's and 10.5's that I wouldnt have to pay the custom-fee for. I dont really wanna drop to 9.0:1 because I am going to have a fully built engine and dont think I need to go down that far to boost it. but I think 10.5 might be a bit much. but letrs just say I got a b20 with ductile iron sleeves, crower forged rods, JE 10.5:1 pistons, ARP rod bolts and head studs, VTEC head, titanium retainers, dual springs, stock crank, dyno tuned with the hondata s200 or the AEM EMS, FMIC and of course all fuel needs covered, would 10 psi daily be atainable, whatever i do though I just wanna run on 92 octane chevron supreme. but sometime maybe hit the track on E and get a couple gallons of race gas and bump the boost up to like 15 or 16 psi.?? or would I have to go down to like 9.0:1. I guess I could pay the extra and get something like 9.5:1-10:1.

[Hypsi87]

if you are looking for performance, lower your compression wayyy down like 8:1 or 8.5 to one and run massive ammounts of boost. The ammount of gains you get with boost does not compare to the ammount of power gained by an extra point of compressioin.

[mycivic]

With that C/R and boost, you are going to have to run race gas all the time. 92 octane rating wont do it.

[Polygon]

You're misguided here.

No matter how strong your internals are, no matter how good your fuel management is, and no matter how well you tuned the car if you experience some detonation at WOT at that compression ratio you will crack your valves, crack your pistons, bust your pistons rings, and blow holes right through the top of your pistons. You will turn that engine to scrap. For the street you need to lower your compression ratio to between 8:1 and 9:1. If you go any higher using pump gas you're playing with fire. If the car was a pure race setup and all you were going to run was race fuel then I would say higher than 9:1 is fine, but if you plan on running pump gas at all you had better have it at 9:1 or lower. The risk of detonation is too high. Like Hypsi97 said, at an 8:1 compression ratio you will be able to run gobs of boost which will more than make up for the lower compression ratio.

My 89 GTC was set at an 8:1 compression ratio and I ran a best of 14.6 in the 1/4 @ 98 MPH. That was with a very restrictive exhaust and running at 13 PSI. The car was also 13 years old at the time and had over 140,000 miles on it. Don't worry about lowering the compression the gains far outweigh the downsides.

[Hypsi87]

The Turbo Buick Outlaw class cars usually run a anywhere between an 8.50-9.0 qtr mile. and the higest compression raito on thoes cars is 9.2:1. They make up for it by runing 32+ LBS of boost on race gas. These cars are street leagal as well.

Now im not saying that you car is a turbo buick or that your car is similar. Just giving you an idea as to how compression raitos are on turbo cars. Almost anything that you do to a N/A car for performance will hurt the performance of a force fed car.

[18c5sol94]

That sucks for people in california we only get 91 octane on a 11:1 c/r on 91 octane with a block guard and inline four head gasket on say 8 psi is it possible. i know it is possible cause i know people that have that setup but 91 octane that is kinda of low

[Polygon]

Originally Posted by 18c5sol94

That sucks for people in california we only get 91 octane on a 11:1 c/r on 91 octane with a block guard and inline four head gasket on say 8 psi is it possible. i know it is possible cause i know people that have that setup but 91 octane that is kinda of low

Yeah, it's possible, but it's also risky. On 91 octane fuel at low levels of boost at a 10:1 compression ratio you're playing with fire. If you ever get a bad batch of gas, and it is known to happen trust me I know, you will get detonation and it will break something. It is possible, but it is a bad idea.

[mycivic]

Originally Posted by Polygon

On 91 octane fuel at low levels of boost at a 10:1 compression ratio you're playing with fire.

Man, are you really gona screw your engine when engine knocking happens. We in CA should at least have 93 or 95.

[18c5sol94]

Originally Posted by mycivic

Man, are you really gona screw your engine when engine knocking happens. We in CA should at least have 93 or 95.

man tell me were to find some 93 or 95 in california. i know for a fact there is not one gas station in the entire bay area that has higher then 91. what if you ad a octane booster will that help

[Polygon]

Originally Posted by mycivic

Man, are you really gona screw your engine when engine knocking happens. We in CA should at least have 93 or 95.

Oh yeah.

Detonation is no joke and durring a race at WOT if you get detonation it will be the end of something in that engine even at low levels of boost.

[Hypsi87]

Originally Posted by Polygon

Oh yeah.

Detonation is no joke and durring a race at WOT if you get detonation it will be the end of something in that engine even at low levels of boost.

and it does not matter what internals you have, stock or completley forged/billit/full race ready to go setup, detonation will kill it all

[boosted331]

Originally Posted by Hypsi87

if you are looking for performance, lower your compression wayyy down like 8:1 or 8.5 to one and run massive ammounts of boost. The ammount of gains you get with boost does not compare to the ammount of power gained by an extra point of compressioin.

Remember this is a small-bore honda we're talking about here, not a GN or another big bore motor. Smaller bore means the flame travels quicker over the top of the piston, and the motor will resist detonation far better than a larger bore motor will. 8:1 on a honda feels downright doggish, spool is much slower and the compromise isn't worth it, because you can run 20 pounds of boost on pump gas with 9:1 compression, and make more power than you EVER need for the street. ITR's have 10.6:1 compression, and JDM ITR's have 11:1 compression, and you see a lot of people that boost them. Running a good DFI setup (AEM, FAST, Haltech, ACCEL, etc) with a GOOD TUNER who knows what they're doing, you shouldn't have a problem with 10.5:1 and 10 pounds of boost on 93 octane. Honestly though, if this isn't a hardcore race motor (which it sounds like it isn't going to be) go pick up a set of off the shelf 9:1 pistons from JE, it's not like that extra point and a half of compression is going to add 50 HP and 50 ft-lbs down low and make the car much more enjoyable to drive. In my motor i'm running 83MM 9:1 CP pistons, low end is fine, and it gives me lots of flexibility on pump gas.

[94tegRS]

I am thinking of instead of worrying about buying a B20 for displacement and tweak that, I am considering just starting with a GSR and gettting the crower stroker kit to bump it to 2.26L, and then get like either 11:1 and go NA or go 9.0:1 and throw on some boost. if I were to get say 9.5:1 and not boost it right away, what kinda performance would it have, because with the cost of the stroker kit, AEM EMS, and fuel mods, etc... I wont be able to afford the turbo kit right away. but I will have the large injectors, lots of fuel flow, computer, engine all ready and able to handle the boost, just wont be there yet?

and what kind of power you think a 2.26L 11:1 GSR with I/JDM 4-1/2.5" exhaust with a slight fuel increase and good tuning have and then at the track I can just spray(direct port) and forget the boost all together.