300hp-high compression > low compression?

[jeffmsp]

hey guys,

i am wondering ideas on how to make 300hp. Yes rods are coming soon. Nothing is going in until properly assembled since i cannot afford mcuh downtime. What I am wondering, is should I keep the stock pistons and stock compression (I am not interested in lowering it) or should I raise the compression to say 10:1 and tune with an aftermarket ems. I am not looking to get rid of the stock turbo. I like it, spools good and works fine. I am not looking for a drag car at all with the vehicle, I have plans for eventualy an AWD system sourced from a salvage wrx and I am looking for a good powerband to get me through the twisties.(yes, the car will be butchered right down the middle for a better cause) Ive driven a few wrxs and I hate the low compression ratio in them. The motor just feels like a dog. 10:1 isnt crazy, and I think I will be able to hit 300 flywheel hp with them and have a better powerband than say keeping the stock compression and upgrading the turbo. Off boost performance should be increased also. Ive also never seen anybody else with a FS do a high compression, medium boost setup so i figure i should try it out. Think I will be able to adjust dsms a/f controller enough to tune the beast or am i in need of a haltech or other system?

thoughts?

 

[SpicyMchaggis]

Higher compression = more bang bang

Which is nice, more power per psi..but...a lot more stress on the internals. Doesn't matter if they are forged or not.

Your probably better off dropping to 8.5:1 and just rocking up some big boost.

 

[Kooldino]

You can do 300chp on stock compression. It will be harder to do on 10:1. If you MUST raise compression, go with 9.5:1. But Staying at stock would be better. Also, if you want some cheap used forged pistons, see my sig.

 

[jeffmsp]

why would stock be better though? i would be using an ems. i know it would be a safer compression, but then im just running more boost to compensate meaning I will need to upgrade the turbo and the car drives like ass when not in boost. if i was going 300+hp i think that would be the way to go, but i am not really interested in making my protege into an srt-4.

 

[Kooldino]

why would stock be better though? i would be using an ems.

Well, you're talking to someone who had stock compression forged pistons and moved to lower compression forged pistons.

Sure, you can retard timing as the boost level increases, but on stock compression, after 12psi you have to start pulling so much timing to avoid knock that it starts getting almost counter productive.

i know it would be a safer compression, but then im just running more boost to compensate meaning I will need to upgrade the turbo and the car drives like ass when not in boost.

By the time you hit 15psi on our motors, the fact that you'd have pulled less timing on the lower CR vs the stock CR might be enough to make the lower CR produce more power. Maybe. If not, it's damn close. I'll tell you shortly.

As for the lower CR driving like ass, that's just not true. My 8.5:1 CR barely feels any different than it did stock.

if i was going 300+hp i think that would be the way to go, but i am not really interested in making my protege into an srt-4.

If 300chp is your goal, stick with stock. Just don't go higher.

 

[flat_black]

Go for it! Get a something like 9.5:1 compression pistons, then increase the quench area on the head to help reduce the chance of detonation. =)

If you're crazy, and want to try it, you could attempt a trick I was thinking about trying; Decrease the stroke by using a 1.8L FP-DE crank/rod/piston setup, (replacing the rods and pistons with forged versions, of course) so your stroke is lower. If you want to go fully custom, get the wrist pin pushed up toward the top of the piston more, and lengthen the rods even more, so you have a much, much better rod ratio than stock. The pistons you drop in should be set for a 2-3mm overbore, and the block bored out appropriatly. Once you get all that done, you'll have a 1975cc engine, rather than a 1991cc engine. Still pretty much a 2 litre, but it'll be much happier to rev for you, I'm sure. =)

Optimally, I would have a custom crank made, so I could run 1999cc's; 86mm stroke by 86mm bore.

But I don't have that money. =) If you do, go crazy!

 

[jeffmsp]

ya that sounds amazing but kicks my budget it the face. If Im keeping stock compression then I guess I could spent the money allotted on pistons for a hybrid turbo. anybody here familiar with AWD swaps? Im pretty sure the donor car will be a wrx providing i can get an adaption plate made for the trans. The drive shaft i guess will have to be done custom, not sure if the front axles will even fit right. any ideas on that or any other cars that may be a better fit? thanks

 

[edaddeemsp]

Although you may not want to make your msp into an srt4, you may need to look into the compression that the srt4 has, along with the turbo size. Actually since your actually wanting the awd platform, check the compression, along with psi of a evo.
As far as the awd idea, i've seen it done with honda/acura's, so I dont think that its without reason. But i know when they performed the task, they used a vehicle from the same manufacturer. So basically imo i'd check the specs on something more in the line of an awd tribute. just my thoughts. But an awd msp would be very nice.

 

[jeffmsp]

it will be done. i dont think using system from different manufactures will be a big problem since everything is going to be gutted and i do not require any electronics to coinside. Nothing will bolt up, but that will be half the fun. I just wish i started with a normal 2.0l protege since i seem to replacing everything anyways lol

 

[Kooldino]

As far as the AWD goes, Search for a thread here called "AWD the wheels are turning" or something.

He plans on doing it with an AWD P5 from Japan.

 

[Brian MP5T]

SUBSQUIZZLE

 

[Kooldino]

BTW, Xelderex is the guy who plans on doing it.

 

[chillinmcmillan]

hey jeff good luck with your goal, how those winter tires treating you?

 

[jeffmsp]

they are mint,i swear i was going to sell my fmic then my speed cause i was getting pissed off, but those winters and the resurection of my mbc got me good again.

 

[BlkZoomZoom]

Lower compression and more boost makes more power, it's been proven many times.

More than likely you will never notice the difference between 10:1 and 9:1 pistons, especially with 300hp. You'll never have enough traction to even worry about it.

As far as keeping the stock turbo just because you don't want longer spool up, call MPNick. Have him mill out your turbo compressor side and install a bigger wheel. You will have the exact same spool up as stock because the turbine wheel isn't changed. Plus you'll have the potential of some big numbers.

As far as a wrx donor car, that would be wayyy too much work. I suggest finding a donor where the motor is mounted the same way as the Protege.

 

[Kooldino]

Lower compression and more boost makes more power, it's been proven many times.

More than likely you will never notice the difference between 10:1 and 9:1 pistons, especially with 300hp. You'll never have enough traction to even worry about it.

As far as keeping the stock turbo just because you don't want longer spool up, call MPNick. Have him mill out your turbo compressor side and install a bigger wheel. You will have the exact same spool up as stock because the turbine wheel isn't changed. Plus you'll have the potential of some big numbers.

As far as a wrx donor car, that would be wayyy too much work. I suggest finding a donor where the motor is mounted the same way as the Protege.

Evo or anything 4G63 based?

 

[jeffmsp]

well gtx awd trannies are quite plentifull but the are like glass. Would fit nice though. time to go find one and see how well it will mate up. I guess the rear end I can pull from a bunch of different cars and the shaft is gonna have to be custom. Good thing the gtx tranny uses no electronics.

 

[BlkZoomZoom]

Evo or anything 4G63 based?

huh?

 

[BlkZoomZoom]

I haven't seen many problems with the R32 tranny or diff. of course the electronics alone would probably kill that idea.

 

[jeffmsp]

ok i e-mailed a bunch of places, and i once trained a guy at work who owns a j-spec motor import business and he says he thinks he has a gtx awd tranny. I think I will need the gtx diffs and rear end or else the gearing will be messed. I think I can find one of those too. Things are looking good. Tranny should cost me around $400 and I havent gotten any prices on a gtx rear end and front/rear axles and assemblies etc. The driveshaft and the rest i guess will be custom. Time to go read alot of stuff. (chair)