Hi comp pistons
 

Does anyone no if there are any of the shelf high comp pistons?

Dave,

All of the Wiseco made pistons are a 9:1CR. Having said that they should have all the measurements to make a high compression version if you request. GTM also has stock compression Arias pistons available I believe.

Why are you looking to go higher than 11:1? Whats your overall goals?

Thanks,
Alex Goodwin
AlexG@motionlabtuning.com

Power!

What is the intended fuel?? That is a major consideration when choosing compression ratio.

Thanks,
Alex Goodwin
AlexG@motionlabtuning.com

11 is not enough nowadays?

Most will do 93. Race bikes are all 12+ and can run regular fuel. I know it's a different machine since 600's rev to 16,000 rpm.

The question is what gets more power? If you go 12+ and have to back the timing out will you have the same power as if you left it stock with more timing? At least have two maps, one with e85, race fuel, or if that torco works and then regular fuel.

So lets look at things a bit differently. Power (HP) is a calculation of torque X RPM / 5252. As I understand it higher compression ratios move the torque curve up on the RPM scale, not necessarily making more torque but more HP just by calculation. The VQ37 engine already makes it's peak power @ 7000 rpm.

So how fast do you want to spin this engine??? I come from the old school so 7k seems like a lot to me already. Can these engines handle 7k or 8k regularly?

Higher compression has nothing to do with RPM.

without racing fuel/e85, I dont think I would feel comfortable going over 11.5 or 11.7 to 1. Generally a street engine that goes higher than 12:1 is using direct injection and or cylinder pressure monitoring.

Please elaborate.

My guess would be that the static compression ratio is the same whether the car is idling at 750 rpm or at redline. ;)

I'm no expert but compression is power, it has nothing to do with rpm. If you cram air and fuel into a space and ignite it, it goes boom. If you cram the same amount into a smaller space (more compression) you get a bigger boom. The more faster bigger booms you get from 2-7k, the more power you make. Hp is basically just a guess calculation from how fast you can get a drum to spin from beginning to end in xxx amount of time. TQ obviously is a measure of the force on that drum.

Now with degreeing the cams, cam tuning/timing, ignition maps etc, you can put the added power where you kinda want it. My race bike for example made about 12 hp from a thinner head gasket. That power started in the mid range from 6-10k. But since you're never really that low, we degreed the cams and moved it above 10k where it was needed more.

All the articles I can find quickly focus specifically on how efficiency is increased by upping the CR. I was referring to CR's effect on the torque curve. If I find something I'll post it.

13:1?
GTM Motorsports*::*ENGINE INTERNALS*::*Pistons*::*GTM / Wiseco VQ Extreme Duty Lightwieght Pistons

Pretty

High compression, more power on lower boost. The tune will matter the most.

The car runs e85 all the time, thinking of an NA build. I no that everyone will say just go forced but I have been there many times and have other toys that are the really fast things.

Same here. I want NA for a reason. Remember though e85 can turn e70 at times so I'd find a better year round fuel or build a winter and summer map.

High CR forged pistons will maximize improvements blend to a cylinder head work and larger cams.
You can even bore and stroke the motor as well.

we have E85 all year in Australia so we don't need to have separate tune's.

Do you guys manufacture it? If not it could be changed if made in the US or else where. I'd always use one of these...

Here in illinois, I have been running E85 for the last 2 years. Before that, I never ran it myself so the last 2 years is all I can speak for...

They have not been changing E85 to E70 or anything like that over the winter. I have asked the stations I used and they told me no. I have never actually tested, but I have seen no change in my A/F or blown up my engine from too much timing. The only time I have ever seen it tested, was a guy with a EVO at the station and his results were E93.. this was well into spring. So I personally have no suspicion that they are cutting it during the winter, at least here around me

Our e85 is made locally and have tested it many time's, we can also get eflex with e70-e85, e70 though the winter for easy cold starts.

Out of topic but why would stations change from E85 to E70 in winter? what's the reason behind that?

Easier starting in cold weather ...

I have 14.7:1 pistons in my race car engine (Alloy 5-litre V8) that runs quite happily on E85. That said, I would not run this engine on unleaded (even 100RON unleaded).

The origin of this thread talked about bumping static compression ratio in a VQ37 which is 11:1 from the factory and I would not go about 12:1 on pump gas UNLESS I was running 100RON fuel AND I also had a knock sensor to tell the ECU when to pull timing.

My previous race engine incaranation ran 12.25:1 on AVGAS 100/110RON fuel (actually called Leaded Race Fuel here in Oz, but getting very difficult to get and quite expensive at $4/litre).

Remember also that US octane numbers are quoted based on MON numbers whereas we in Oz use RON numbers (wikepedia can tell you the difference).

An earlier post talked about upping CR to improve power which is not quite right - increased CR increases torque available with each power stroke (and torque increase is roughly linear with increased CR - so going from 11:1 to 12:1 should be excepted to increase torque by 1/11th or therabouts). Power is a product of torque times rev's, so at the same rpm, a 9% increase in torque will generate a 9% increase in power.

Torque is all about an engines ability to accelerate a car, power is about an engines ability to overcome resistance (eg: to do work). Torque establishes how quickly a vehicle will reach a given speed, power determines (ultimately) how fast it will go (at high speed, the determinant is the amount of drag generated by the body and frontal area).

Gear ratio's also influence these factors.

I would be quite reluctant to increase the CR on a road car without understanding a whole lot more about the Nissan ECU capabilities.

The other point is that the VQ37 engine has an oil-pump that will not survive sustained engine speed above 7500/7800 rpm and it will certainly not survive for long at 8500rpm - albeit that the rest of the engine should be able to tolerate those rotational speeds and more.

The Nissan VQ GT3 and GT4-spec engines all run up to 9000rpm, but they all run NISMO oil pumps and upgraded rod and big-end fasteners to do so.

I personally would not contemplate increased CR pistons without a significant investment in co-requisite mods.

The VQ series heads do not require a lot of modification to flow enough air to support 500+hp at 9000+rpm, but this would require cams, pistons (and careful attention to valve clearance), rods, a full fastener kit, an induction kit (individual TB) and decent exhaust.

Pistons alone are likely to be a WoFTaM.

RB