Hello everyone,

I know that this topic has resurfaced every now and then however now we are in 2021 most Threads are quite old and now tuning technology has improved significantly so my 1,000,000$ Question is Can I use forged pistons with a compression of 11:1 in my GSR engine, I just had Sleeves installed MID Sleeves from Dart I have Manley rods & CP Pistons. I also have a Type R crank and a GSR crank ( Not sure yet which I will be using ) > Your input would also be much appreciated on this.

I also have a Water methanol kit V3 AEM ( not installed yet ) my turbo that I am starting with is a GT30 ( non Ebay lol ) I have the works for the head ( I have both Supertech and BLOX springs & retainers ) 1300 CC Bosh injectors AEM fuel rail, Fuel pressure regulator, ARP Bottom and in the Head, Keeping my A/C I bought a nice thick Ramhorn turbo manifold, I even got the power steering bracket from 1320 performance. Racing Belt, OEM Oil pump, 255 Walbro fuel pump, I also purchased the Coil adaptor instead of using a distributor I think it will be beneficial. I also converted back to OBD1 so that I could use a P28 with a HONDATA S300.

Please keep in mind that I live in Canada and we do not have access to E85 in my area so I am limited to Pump Gas, Petro Canada has 94 Octane and every other stations only have 91 Octane.

- Should I keep my 11:1 pistons or change them to only Flat Tops 10:1 instead for boost. I would love to keep the 11:1 however I am open to suggestions. I have read the thread from 2015 with the 2 blasting each other and calling them names Lol but please lets keep this Nice and Chill and mostly Respectful, Thank you.

 

I think that 11.0:1 is pushing the limits on the 93 octane use, especially with something in the larger GT30 family, but I think it is entirely possible to do it, with some reasonable results as long as the tuning is bone solid, and you use reliable engine management (Hondata S300 V3, Haltech, AEM Infinity, etc) with a competent tuner.

I myself am closer to about 10.5:1 myself, and I will also continue to use Meth/water injection as part of the mix, because I'm not much of E-85 either, and don't really like the investment involved in installing the proper sensors and equipment for E-85, so I'm a bit in your boat also.
I'd really look at the purpose of the car also,and make sure that your Kooks-style manifold is A/C compatible and you have appropriate coatings and wraps on both the turbocharger's turbine housing and exhaust manifold to keep the A/C compressor working properly for as long as possible. You also want to make sure that whatever intercooler you're using is efficient enough (you didn't mention chassis), and do NOT put your meth/water sprayer pre-turbocharger. Put that about 4" in front of the Throttle Body if using a single injection unit.

So, it's up to you. I personally like 10.5:1- 10.6:1, but it really won't matter at this point, as it's only a few hairs off of your static compression. You have the right hardware, now for the proper installation and tuning of that hardware.

So, short answer is ... "with what you got, sure.", My longer answer with it is, "But be careful and make sure assembly and TUNING is of the utmost priority".

I hope that is at least somewhat helpful.

 

^Great info

Id also add that Id suggest running straight wter, no meth. Just add a splash of alcohol to keep algae from forming.

If you use meth, youll either be overly rich, or youll have to pull fuel from the tune and rely on the meth for some of the fueling. This is very dangerous becuase if youre water/meth injection clogs or runs dry, now youre lean and without your anti-detonate. Bad news.

Water alone is an amazing anti-knock agent. The meth is only really needed if you have some kind of horribly inefficient compressor with no intercooler. Like a roots blower for example. With that kind of setup the meths volatility will lower IATs through its phase change.
You still get some of that effect with water, but the main thing youre banking on is the anti-knock ability.

 

Agreed with Full_Tilt on running a primarily water/alcohol mix. Water is also better than meth at lowering EGTs. 11:1 is entirely possible, there's plenty of turbo S2000s on stock pistons running gobs of power for decently long periods of time.

That being said, if you have the option I'd still go closer to 10.5:1, just to give you a little room for error, or a bad/low tank of gas, etc.

 

I ran a 70/30 methanol to water mix in my sprayer and yes, I ran on the rich side. It was not so bad to where I had to pull a ton of fuel really, I leaned it out about .5 AFR more than I would have ran it anyway; running it at 12.0-12.2 rather than 11.5-11.7. The torque maintained was ridiculous though! In a single cam setup at that, torque/HP were pretty darn close ratio: 325/364. There was still a ton of duty cycle left in the injectors as well, they were only 750cc and not even touching the 60% DC range.. I will be running the same spray in my GSR, hoping to see even better results with a similarly conservative tune with larger injectors. The WM sprayer is a good idea for you though, for sure. I'm curious to see how it would do in a higher compression setup. I'll be following this build, sounds good so far.