What are the intended and unintended affects of going the other direction and buying some high compression, N/A pistons for my RS?

I already am verrrrry impressed with the torque and power of my RS. It wasn't obviously neck snapping, but still a pleasant surprise.

Octane? Increase of power? Drastic shift of the curve? History of creating weaknesses elsewhere or exploiting some previously unknown existing weakness?

 

You can get pretty big gains. Dan Coty (dcoty) on nasioc is pushing around 230 or so i think. He can walk a stock WRX at least I've heard. He's doing like 11:1 compression on a built block, I think with PnP of the heads, spicy cams, full exhaust, standalone ECU, I think he runs 94 octane. He had problems with running nawz and blew an engine I think. I know you can move the torque curve up when you use Cobb Tuning heads and cams at least thats their claim. I haven't looked into the TWE stuff. They haven't gotten back to me when I called them. With stiffer valve springs I believe you can also rev to 7k easily. I think you still need to becareful even tho it's reliable. I think you can still fry cylinder number 3 due to lack of fuel or something like that. YMMV as I haven't done this, just in the process of building my engine up and this is what I've found while researching.

cheers

garrett

 

I just got the idea from Rallitek's website: http://www.rallitek.com/products_inn...Y&HB=&ACC=&SP=

12:1 Wow.

 

You can get over 13.5:1 if you really try by mixing and matching pistons, heads, and gaskets. I think 12:1 is as high as you'd want to go on 92-93 octane pump. Basically, you'd need higher CR pistons, headwork, cams, and valvetrain work like TWE's spring and retainer package. Put it all back together and you can get a healthy 210-220 hp and 240+ pounds of torque. You will need spark and fuel control of some sort, but I don't think you'll really need bigger injectors if you keep it under 8000 RPM. The downside is, it's not much less expensive than a basic EJ20 swap, and has less total potential. It is really cool though. I'm strongly considering doing this eventually with my next Subaru, which will be an RS wagon or OBS.

 

I'm guessing then, convential MSD and custom pistons would be the minimum requirement. You know, with this setup what would be supremely sexy would be to have true dual exhaust made. I guess, a little less sex (but still awesome) would be stronger springs and retainers.

Cool. I may have to look a little closer at this.

 

Yeah I think what BANSUVS said would be pretty killer. Me and my pops were talking about this the other weekend. He restores old cars and hot rods and is still into the whole "Displacement displacement displacement!!!" I have to say the idea is cool and pretty unique still as less than a handful of people are making big numbers by going n/a... there's prolly a reason for that he he.

I remember hearing that you really wouldn't want to go over 11.2:1 compression on pump gas. At least in California on our 91 octane. Does the MSD hold up well in this application?

By going dual exhaust I think you'd lose too much velocity in the pipes and would ultimately hurt the power. Plus you'd also have splitter in there going from 1>2 seems like it'd be more trouble than it's worth.

cheers

garrett

 

Yeah, the true dual exhaust thing... then you get two extremely dinky motors instead of one that sounds better than damn near anything. Not sure it's such a good idea (plus, the optimum piping size would be like 1.5"... what's sexy about that?

By MSD ignition, do you mean a controller of some kind or replacing ignition altogether? Subaru's actually got good ignition components from the factory. You just need an ITC or RS reflash or standalone like a Link Plus to tie it together. An AFC would be fine on a '98 or older Impreza.

11.2:1 on 91 is probably pretty close to the truth. The springs and retainers are unnecessary for less than 7k RPM, but a good NA build would give you cams that want to run higher than that anyway, so I'd recommend them.

 

I haven't really hearding anything about using non factory ignition, it was just mentioned in a few posts above. Didn't know if I was missing out on something. I would probably just do a reflash if there was one available. I don't think anyone has one yet for the RS. I know i-Speed is close and Cobb's like "dude i swear it's coming out just hold up a sec."

If you were using the stock cam you wouldn't have to worry about valve floating? My understanding is that the stock springs are like soft enough to use in a mattress.

cheers

garrett

 

It's not the springs that limit the revs, its the cam itself. Stock RS cams are totally useless above 6000 RPM without forced induction. The springs are a bit soft, but people have run up to 7k with them no sweat (one with a 420 whp RS-T). I personally plan to get the TWE retainers and springs so I have enough to go to 8k if I want to. Planning on ~7400 for now with the turbo motor.

Yeah, in hindsight, I think the Link for like $700 or $800 is a better idea than a $500 reflash, provided they ever actually exist. Especially considering tuning time.

 

I am unique in that I feel pretty darn confident discussing US WRX's and generic EFI and FI, but I feel like a n00b when the dialogue progresses to anything n/a.

When I brought up MSD, I was just gathering that they may produce something that would work. I know that as little as a year ago, they introduced a couple of new products for a general EFI, forced-induction, 4 cyl car; but within a few months, it turned out that it wasn't compatible with the WRX. However, I know that a buddy with an RS-t was able to use it. I was just making an inference that something similiar by MSD might work on a 4 cylinder n/a application.

I don't know who would reflash the RS ecu; I'd guess ECUTEK...but I don't know.

If I planned to run 93 octane, would 12:1 be stretching it? Here shortly, when I get my WRX up and running; I hope to find some hardware store or something that sells xylene by the big barrel.

***, I don't know about the springs. I can't imagine them being toooooo much softer than a WRX...but I've been wrong before. I wonder if www.rs25.com or nasioc N/A has anything in their archives.

...Good stuff.

 

In either FI or N/A can you use a Link Plus replacing the stock ECU (Guess thats how it would work?) and pass smog tests. Specifically california.

cheers

garrett

 

Que? Link has OBD-II built-in? That's all that keeps any stand-alone from passing smog checks anywhere.

 

Errr, nevermind... you could do it on pre-OBD cars. That's probably where that info came from.

 

Sorry I guess that wasn't written very well. I was wondering how one would pass smog test without a OBD II port. I have an 01 and was curious if I ran a Link system how I would deal with smogging it. But as you more or less said... I wouldn't.

cheers

garrett

p.s. congrats on 11,000 thats a lot of posts.

 

Crikey! I need to go outside now...