Turbo options?

BAC5.2 · #1 04-04-2007, 06:53 AM

There's a few of you Turbo boys on here, and I had a question for those of you who have gone to the dark side.

What turbo did you choose, and how does it spool?

Has anyone been daring enough to attempt a twin turbo setup? Not necessarily for lotsa power, but rather for seamless spool and power delivery.

I was wondering how the EG33 would handle spinning two GT2876's. Max boost would only be around 7psi.

How much boost are you guys running on otherwise stock motors? How much power are you making?

I have no intention of turbocharging a stock internal'd motor, but I'm debating compression ratio, and which direction to go. From what I recall, the stock CR is something like 10:1 or so, and it requires premium fuel.

I am considering a turbo or a supercharged setup, where low-end torque is of the utmost importance, second only to perfect reliability.

What do you guys think?

Crazy_pilot · #2 04-04-2007, 07:14 AM

A twin turbo settup has never been successfully done in an SVX, to the best of my knowledge. It's been tried on EG33 engines in other applications, but I haven't heard of one that works. TomsSVX has probably gone the furthest in trying a twin turbo system for an SVX. *Searches for thread*

http://www.subaru-svx.net/forum/....

The single turbo guys are Phast SVX and cdigerlando. They can probably answer your turbo questions better than most.

Of course, several members are running the ECUTune Stage III supercharger as well. From what I've read, if you want low end torque that's the way to go. The blower makes boost from idle, so you've always got power.

mikecg · #3 04-04-2007, 07:32 AM

As far as boost pressures go, My Stage III has been running at 9lbs with no major issues for about a year now. TomsSVX was running around 12lbs and his ring lands gave out. The only issue we're having with our setups is the breathing of the engine. The heads and cams cant scavange enough of the gasses out at higher RPMs. Our dyno graphs are a down hill slope. You can check my locker if you want to look at the dyno plots.

BAC5.2 · #4 04-04-2007, 07:50 AM

Really? So a set of forged pistons and rods and I'll have a bullet proof bottom end for my application.

I'm not TOO concerned with top end power. Low end torque is more important.

The only caveat, I do not want to intercool the setup if possible. At the MOST, I want to do no more than an air-water intercooler. That's a part of the twin-turbo idea. Get two turbos pumping half as hard, and I can drop intake temps.

The SC idea is a good one, but until the kit is available with parts only, it's not an option. I must be OBD2 emissions compliant. I was planning on replacing the cams with something designed for forced-induction at some point down the line. If I could get the SC kit with just the intake manifold, the pulleys, and such, that'd be great. I would want to use the Whipple 2.3 blower though, not the Lysholm 1600AX.

I'd be happy with 300whp/300lb-ft. Ideally, I'd like to see around 450/450, but I don't think that'd jive with the daily-driver aspect. If I could make 300lb-ft from 3,000 RPM to 5,500 RPM, I'd be very happy.

What's the factory rev-limit on these engines? 6500 like most other Subaru's?

sicksubie · #5 04-04-2007, 08:14 AM

There are buys right now for the valvetrain and cams. Pistons and rods were just ordered though. You can try LAN and see if you can still get them. Yes 6500 is the rpm limit

TomsSVX · #6 04-04-2007, 08:47 AM

we are only seeing tops of 250 whp right now so reaching 300 is gonna be a tough task

Tom

BAC5.2 · #7 04-04-2007, 12:52 PM

How are you stuck at 250whp? Is it an engine management issue? Stock block issue? Heads and valvetrain issue? With 3300cc's, I didn't imagine the output record was so low.

I've hit 300whp on EJ20's so many times, I've got a formula for it.

It can be done though, I'm sure of it. Smaller displacement cars have made more power out of the box. Lower compression, and a good amount of boost, and that should be the ticket.

What turbo are you running?

TomsSVX · #8 04-04-2007, 01:35 PM

no turbo... stage III supercharger... not engine management but simply lacking the proper profiles on our cams... New cams and a full engine build comming soon.

Tom

sicksubie · #9 04-04-2007, 02:12 PM

Quote:

Originally Posted by TomsSVX

we are only seeing tops of 250 whp right now so reaching 300 is gonna be a tough task

Tom

Are you saying that 300whp is going to be tough even after the pistons, rods, P&P head, valvetrain, cams, and the S/C kit. I was hoping that with the built motors I could maybe go to 14-16lbs of boost.

TomsSVX · #10 04-04-2007, 11:21 PM

I plan on running 12psi on pump fuel and maybe 15-17 on race fuel... we should be well over the 300 wheel mark with the built motors running 12 psi

tom

sicksubie · #11 04-05-2007, 08:05 AM

Quote:

Originally Posted by TomsSVX

I plan on running 12psi on pump fuel and maybe 15-17 on race fuel... we should be well over the 300 wheel mark with the built motors running 12 psi

tom

that is awesome...

Pure_Insanity8 · #12 04-06-2007, 04:11 PM

Quote:

Originally Posted by mikecg

As far as boost pressures go, My Stage III has been running at 9lbs with no major issues for about a year now. TomsSVX was running around 12lbs and his ring lands gave out. The only issue we're having with our setups is the breathing of the engine. The heads and cams cant scavange enough of the gasses out at higher RPMs. Our dyno graphs are a down hill slope. You can check my locker if you want to look at the dyno plots.

Jeez, you've had that in for a year already? Time goes fast.

I sure hope the new cams aren't shooting for more scavenging. Since that is what we don't want to go on with forced incuction... we need less overlap (hence less scavenging).

I hope to see these new cams and exhaust clear up the power restrictions. I would imagine 9 psi would generate around 300 whp and 12 psi making well over that, like you said, Tom.

I've actually been wondering if anyone has engine analyzer pro to test out new ideas. I just started using it for my thermodynamics class and wow does it do a good job of estimating. It usually overshoots power predictions by about 5% but it provides a great idea of what actually works and what problems you could run into with the changes made (like valve to piston clearances and detonation problems). I'd like to put the EG33 into the program but there is a lot of info I'd need.

Phast SVX · #13 04-06-2007, 04:36 PM

Quote:

Originally Posted by Pure_Insanity8

Jeez, you've had that in for a year already? Time goes fast.

I sure hope the new cams aren't shooting for more scavenging. Since that is what we don't want to go on with forced incuction... we need less overlap (hence less scavenging).

I hope to see these new cams and exhaust clear up the power restrictions. I would imagine 9 psi would generate around 300 whp and 12 psi making well over that, like you said, Tom.

I've actually been wondering if anyone has engine analyzer pro to test out new ideas. I just started using it for my thermodynamics class and wow does it do a good job of estimating. It usually overshoots power predictions by about 5% but it provides a great idea of what actually works and what problems you could run into with the changes made (like valve to piston clearances and detonation problems). I'd like to put the EG33 into the program but there is a lot of info I'd need.

Ive taught myself solidworks, but ive found it much more efficeint to just use basic theory and go ahead and do it.....I have no show care thats for sure but im also not looking to push 600hp

Pure_Insanity8 · #14 04-07-2007, 01:11 AM

Theory works for basic and simple modifications, but changing cam profiles, pistons/rods, compression ratios, etc. to take advantage of forced induction while getting the best result (efficiency) for the work/money you're putting in... some good software sure does help. That would be why most serious engine builders use these programs. Could make the difference between 300 and 350 ponies for the same amount of money spent.

Have you driven your SVX lately? I'd love to see you make 600 hp... even if you're not looking to.

BAC5.2 · #15 04-07-2007, 08:31 AM

If 300whp can be done at around 9psi, that sounds more like what I was thinking.

What kind of compression ratio is the built motor running?

The basic structure of the EG33 is similar to the older EJ20's, so with good pistons and rods, it should be able to undergo the pressures of the EJ20 (which, when they had a 16g on it, ran near 14psi). 14psi should make, easily, 375whp in an EG33, don't you guys think?

As far as cam profile goes, why not just copy the profiles from one of the factory DOHC turbo motors? Head and valve design is similar, so why not just have a set of cams ground to match the cams from an STi or something? Or is it not that easy?