Pro's/Con's On 9:1 Compression and who's running it?

[4g63telantra]

Just wanna know if anyone is running 9:1 Compression pistons on a turbo set-up and what are some like's and dislikes about running that compression?

and

What are some reasons to be running 9:1 Compression?
Better for bigger turbo's? higher boost?

 

[turbo2086]

Well with higher compression pistons, you will need to be running lower boostt. However you will have a little more power when your NOT boosting due to the higher compression pistons.

In lower compression pistons, you will not have as much power when your not boosting. But, you will be able to run more boost.

 

[blackGSX2g]

I run Wiseco 9:1 comp pistons and love them.

I gained more off boost power, better gas mileage, and far quicker spool up. Keep in mind that when you up the compression, you will need to have a better tune and more fuel to run higher boost than people with lower compression. With my current motor set-up and a stock fuel system, I couldn't go over 13 psi on an EVO III 16g without getting horrible knock. Even then, it still pulled harder than my buddy's 2g FWD with the same turbo at 18psi with aftermarket fuel.

I also blew out a crappy composite headgasket this way, so I'd recommend going with a Mitsu MLS 4-layer.

 

[GVR4592]

You can run just as much boost with 9:1 as you can with 7.8:1 or 8.5:1. It all depends on your tuning capabilities. You will make more torque through the whole rpm range with higher compression. Timing advance and intake temps are the things you need to regulate the most when you have higher compression. There's guys on this forum with 10:1 compression and 20+ psi in their daily drivers.

 

[1LE]

I'm at just around 9.1:1 and usually run 14-16psi, with 18psi being the absolute upper limit on pump gas with my TRE 16g. I guess I can say "it works". Car is very fast for those boost levels. Hard to tune though. G-Force ECU + VPC/GCC and they all depend on the engine's "reaction" being somewhere near stock. It's far enough off now that I have to go too rich before boost down low so I don't go lean when the boost hits. So, I lose all the benefits of 9:1 as far as spool up. Biggest issue though is timing. I get too much for this setup.

So, in short, it's a good way to go, but only if you're going to have the tuning equipment to compensate for it!

Oh yeah, 28mpg average, even with the 10 minute warmup required by my engine builder...

 

[blackGSX2g]

Hard to tune though. G-Force ECU + VPC/GCC and they all depend on the engine's "reaction" being somewhere near stock. It's far enough off now that I have to go too rich before boost down low so I don't go lean when the boost hits. So, I lose all the benefits of 9:1 as far as spool up. Biggest issue though is timing. I get too much for this setup.

Are you on the stock fuel system or aftermarket?

I tried using 650 injectors with MAFT on my car and had timing and low end problems. MAFT cannot compensate for injector dead time the same way DSMLink or another standalone does. It gives the ECU less airflow signals so it pulses the injectors slower. Because the ECU thinks less air is coming in, it gives you more timing. Problem can be solved by getting a device that provides compensation AT the ECU instead of lying to it.

As you posted, your problem lies in tuning not 9:1 compression.

 

[1LE]

Are you on the stock fuel system or aftermarket?

550 injectors (which are maxed out at 18psi), 290lph fuel pump, Buschur bolt-on AFPR.

 

[gotlag]

When I ordered my pistons, I had them cut for 8.9:1 knowing both my block and head had been decked and it brought me just over 9:1. I did this as I planned on keeping the auto in my car and I can tell you it did make a difference compaired to my last build up at 8.5:1. I did have to add a bit more fuel at the track, but my milage went up on interstate driving. I can't think of a single reason why I would ever build another with lower than 9:1.

 

[Eclipsei95cl]

550 injectors (which are maxed out at 18psi), 290lph fuel pump, Buschur bolt-on AFPR.

550s maxed? on a 16g with only 18psi. I dont think you can max those 550s out at 18psi. You must have other problems.

 

[Eclipsei95cl]

a 290lph fuel pump is huge. You sure you dont mean the 190?

 

[tstkl]

290 lph = supra fuel pump

higher octane should help some with higher compression

a mitsu 4 layer metal head gasket will lower the compression a little due to its thickness...

 

[turboguy25]

550s maxed? on a 16g with only 18psi. I dont think you can max those 550s out at 18psi. You must have other problems.

You can max out 550cc injectors on a stock 1st gen 14b. Its done all the time

 

[1LE]

550s maxed? on a 16g with only 18psi. I dont think you can max those 550s out at 18psi. You must have other problems.

It's possible, given enough mods in the right places

 

[Eclipsei95cl]

hmmm at 18psi though..? I know someone that has a 1g with a fp3052 made 400whp on the dyno running 550s but at that point he had maxed the injectors. Just never heard of 550s getting maxed out alot on smaller setups..

 

[4g63telantra]

Would 9:1 Compression pistons work fine on a 60-1 turbo? (with many other mods) + (DSMLink)

Anyone on here running that setup?
If so how do you like the 9:1 on a huge turbo?

 

[gsx951]

Just wanna know if anyone is running 9:1 Compression pistons on a turbo set-up and what are some like's and dislikes about running that compression?

and

What are some reasons to be running 9:1 Compression?
Better for bigger turbo's? higher boost?

Drive across town and go speak to Marco at Magnus.

 

[1LE]

hmmm at 18psi though..? I know someone that has a 1g with a fp3052 made 400whp on the dyno running 550s but at that point he had maxed the injectors. Just never heard of 550s getting maxed out alot on smaller setups..

Pump gas. 400 crank HP (engine dyno) before install into car.