Daniel_TL

ok so i seen ppl on here talking about wiseco pistons in j32's but i cant find j series pistons anywhere so dose anyone got more info on them ?

Hi speed

iTrader: (3)

I think the J32 pistons still need to be custom from Wiseco. Last I looked about $900.

Daniel_TL

so there made to order ?

justnspace

iTrader: (1)

^yep.

rush

iTrader: (1)

$900 shipped you choose your compression ratio

Daniel_TL

what do you guys think the highest compression ratio to run safe with a supercharger ? but still get more power then stock i was thinking 12to 1 is that to much or can i go even more ?

bouncer07

Very Doable, yet, building an engine with that sort of CR ought to have been done with a clear picture of what sort of induction system you were intending to use. That high a CR might require pulling too much ignition advance (especially if you don't have an efficient A/W intercooler setup), although water or meth injection might be able to help get around that. You may need a cam stage higher than a stage 2 Bisi also offers and will almost need to run fuel E85. This will be a complete monster set up as those CR are All motor configures.

Unless... try going lower. Have a better understanding on it unless you have a plan and very knowledgeable on tuning and cars.

KN_TL

iTrader: (3)

KMS also has pistons for the J32

http://www.honda-performance.com/info-lv2.asp?id=366

Daniel_TL

ok i was going to use the ct engineering charger pauter rods the wiseco pistons i talk to bisimoto asking if there cams would be ok to use with the charger and they said they can custom make the cams for my set up i just didnt no if the engine take take the 12to1 with the charger

Hi speed

iTrader: (3)

Why not use a larger SC and lower comp to 10:1. If you drop 6-7K on a building a engine, why not make some big power. The stock engine at 11:1 is pretty knock prone, 12:1 would most likely mean 100+ octane all the time.

EvilVirus

iTrader: (8)

OP you got to learn to use punctuations. Anyway, its best you lower compression than to raise it.

yungone501

iTrader: (4)

I bought a set of Wiseco's for my last build and paid around $880 shipped. They were available in two base compression ratios and dome shapes but if you had specs, they could match them for a small fee. I sold mine to Andy after deciding to go with a j37 build. Expect to pay around $2k for aftermarket pistons and rods.

I hate cars

Some good and some bad advice here.

In determining what compression ratio you want to run, you need to figure out the minimum octane it will be run on and how much boost you plan to run, along with charge air temps.

On street turbo engines, I like low compression, my personal car runs 8.5:1 but I also run 30+psi boost. Our engines already have a pinging problem on the stock 11:1 compression ratio with premium fuel without the supercharger and these cars do not use much timing as it is. The more you retard the timing, the higher the EGTs go and the more likely you are to do damage to exhaust valves and cats if you run them. Ignition retard can only go so far. Eventually you make things too hot and combustion peak pressures occur too far after TDC and you start to lose a significant amount of power.

If you plan to run methanol all the time as in from the time it gets to zero vacuum to full boost you might be able to get away with 12:1 compression but if the meth fails, your engine fails. 100 octane unleaded should support a 12:1 build with only 8psi as long as the charge air is not superheated. Again, personally I rely on the methanol for about 20% of my fuel at full power and I've got a wall of blown headgaskets from when a jet plugs up or when a switch fails so I don't recommend anyone else do it but it makes good power.

For a good street engine with only 8psi I personally would go 9.7:1 and use a meth kit for safety and to cool things off especially if you're not using an intercooler. This will allow close to stock ignition advance to keep things working well for a long time. This would put you right at a 12.0:1 effective compression ratio which you could probably get away with safely on just pump gas. For safety, the meth is still highly recommended, especially for it's cooling properties. For what it's worth, 12.0 effective compression is a good number to use for an aluminum head street engine wanting to run pump gas.

Let's not forget that at most a 1 point increase in compression will give a 3% boost in power....at most. A 1lb increase in boost will make that power back and then some. For each point decrease in compression you can run considerably more boost to get back to your maximum effective compression ratio.

Keep the future in mind as well. Build it for a worst case scenario. If you think there might be a turbo sitting in there one day making 20+psi of boost and this setup is just a stepping stone, 8.5-9:1 would be the better choice. If you wanted more boost without changing the compression ratio, run more octane or methanol. In the end it's a balance beween compression, octane, and boost.

Totally irrelevent but since people like to give extreme examples, Top Fuel dragsters run around 5:1 compression but they've got a TON of boost and cylinder pressure with the nitromethane and their effective compression ratio is incredible.

Last, remember that detonation kills engines. You must have a knock monitor even if you use no other gauges. Nothing else is as important if you want the engine to live.

I hate cars

Bigger cams will make higher compression a little less likely to detonate by lowering cylinder pressures at low rpms and 12:1 is going to be a problem even at part throttle and without boost. I would get the 12:1 thing out of my head if I were you.

yungone501

iTrader: (4)

I 100% agree with IHC's statement of the knock/detonation controller. Single most important monitoring system by far. Detonation is basically ignition or combustion at the wrong time. Typically this is before or after TDC but its generally the before TDC position that can really be detrimental or damaging to the mechanical integrity of engine and its parts. This, if you think about it, is an opposing force against the pistons dome at unthinkable strength. If your piston is traveling upwards as the fuel has already began its combustion process, these two collide and it's generally the piston, the rings or the rod that give out first. Especially at higher rpm's, that force can be much greater because the injectors are spraying much more fuel into the cylinder AND the piston is traveling at a higher rate of speed. Forged components can take detonation better but just like any other component in the engine, it will eventually fatigue and break.

A knock controller is an idea system to have in a situation where boost or nitrous will be used. They can automatically tweak and adjust ignition timing on a cylinder per cylinder basis (aka: cylinder trim) so that if cylinder 2 is detonating, the unit can retard the ignition on that one cylinder while keeping all others advanced and maintain the engines fullest power potential.