285 whp!

[dynomatt]

Actually, looking at the Flickr thread in Bob's signature, I notice the new exhaust headers.

Bob, did you flow test the factory headers? Did you form a view on their efficiency or did you just replace them becasue you could?

You would have noticed, as I did, that the rear most exhaust port has a lot further to travel than the other two in each head and I was unsure of the implications of that.

Matt

[SVXRide]

Matt,
As good as the stock exhaust manifolds are, they're still a compromise based on packaging and the need for long, trouble-free existence. There are gains to be made in this area!
-Bill

[Nomake Wan]

Originally Posted by longassname

That's a shame; they would be interesting to see but they are his and he certainly has no responsibility to share them. Just be warned that someone is running around using your wheel hp readings to try to make a case that the factory engine management is seriously flawed and that there is 60-70 crank hp to be found by installing stand alone engine management on a stock svx.

I love it when people don't name names. Awesome. Love ya, Mike!

[dynomatt]

Sorry, but here is the scan.

Anybody who can help resolve the torque dip would also be appreciated. It all could point to the timing.

APologies to all those that have seen this before.

[Trevor]

Originally Posted by Nomake Wan

I love it when people don't name names. Awesome. Love ya, Mike!

Originally Posted by RallyBob ---

I haven't seen my WRX dyno plots in years...that was 7 year ago after all. As far as the 3.3RS dyno plots, Jack is reluctant to release them. So that is beyond my control. IIRC a bone-stock WRX made 175-177 whp on their dyno, so my minimal mods added a few hp. I suspect that the swap to full synthetic didn't hurt either (engine and driveline).

Reply by longasname ---

That's a shame; they would be interesting to see but they are his and he certainly has no responsibility to share them. Just be warned that someone is running around using your wheel hp readings to try to make a case that the factory engine management is seriously flawed and that there is 60-70 crank hp to be found by installing stand alone engine management on a stock svx.


N.B. One must assume that Jack is the name, in case confusion occurs and someone here becomes blamed.

[Nomake Wan]

Originally Posted by Trevor

N.B. One must assume that Jack is the name, in case confusion occurs and someone here becomes blamed.

I'm not sure if he's talking about me or TomsSVX. His first response (the one I quoted) seems to be at me, since I've been saying pretty much that a standalone has been successful in bringing out quite a bit of power in an otherwise stock motor. I didn't notice that he had custom headers, but the other mods (injectors which I'm guessing are Nissan, MSI ignition, cold air box) struck me as rather minor in comparison. I'd still be rather interested to see how much one could get out of just messing around with a standalone.

The second one I'm getting the feeling was directed at TomsSVX. Could be wrong, though. Hard to prove intent when someone is trying very hard to be inconspicuous.

[svxistentialist]

Well I think that Bob is answering well and clear when asked direct questions. It also appears to me that he is new to this forum and aware of this newness, and does not want or need to be caught in crossfire between members who are sniping at each other because of what I will call "issues"

Nomake I did say in a reply to you elsewhere that we need to be cautious in evaluating where an untapped 70 horsepower might be coming from, and the cost of extracting it.

Even so, it is still well worth following this line of thinking and seeing where gains can be made. This is the way we will make progress.

It would be good if we could continue beneficial progress for all of us without descending into the sticky realm of unnecessary personal slights and I'd like to thank YT for recognising this and stating his case.

Joe

[TomsSVX]

I do have to agree with Mike. Leaving the engine stock, and using most of the stock components, you will not see 70whp switching to a stanalone. This engine was prepared properly and outfitted properly for Jack's application and I think Bob did a great job doing. Thus they reaped the benefits of having a system tuned extremely well to their application specifically. At no time did I reference that there would be such a substantial gain in power from a SA alone. My point restated again, an ECU that is tuned very well to match the outfit, will provide more benefits.

Tom

[cdigerlando]

Originally Posted by dynomatt

Hey Chuck,

Consistent with the power figures we got, the standard injectors were only running about 75%...we'd banked on getting more, and hence needing more fuel, but didn't happen.

Intake is stock, save that the MAF is gone, exhaust is standard headers with a 2" system joined at a y-pipe under the floor somewhere, then 2 1/2" out with one resonator and one muffler.

Transmission is a stock 6 speed.

Wow 75% duty cycle running 190 AWHP, on stock injectors. Something is wrong. Were you running more fuel rail pressure?

[RallyBob]

Originally Posted by dynomatt

Actually, looking at the Flickr thread in Bob's signature, I notice the new exhaust headers.

Bob, did you flow test the factory headers? Did you form a view on their efficiency or did you just replace them becasue you could?

You would have noticed, as I did, that the rear most exhaust port has a lot further to travel than the other two in each head and I was unsure of the implications of that.

Matt

I did not flow test the OEM cast iron manifolds. But I did not like the fact that the runners merged together very early, I prefer a longer primary runner and a true merge collector, as there is usually a lot to be gained from that design in my experience.

Not to mention we started with an engine that was +/- 82 lbs. heavier than the EJ25 that came out of the car, so part of our goal was to get the front end weight to the same as/ or lighter than stock. The headers are 304 stainless and are quite light compared to OEM. We are currently about 5 lbs lighter than when the car had the EJ25 installed, thanks to creative gutting, lightening, and relocation of components from up front. If we ever come across a GC8 WRX hood (aluminum), there's another 20 or so lbs off the front end.

We're just trying to alter the front/rear distribution and overall weight for improved handling, which is one of the car's strong points when compared to the average caged STI (3300-3500 lb usually with a heavy front bias).

[RallyBob]

Originally Posted by dynomatt

Sorry, but here is the scan.

Anybody who can help resolve the torque dip would also be appreciated. It all could point to the timing.

APologies to all those that have seen this before.

If you are still running the IRIS crossover, then this is probably the cause. I noticed that Jack's car always had a bit of a dip in the both the power and torque curve when the crossover opened up, and when the cams were installed the dip changed to a lower rpm (less vacuum therefore earlier opening). Some of the dip was eradicated with fuel and timing, but it never went away completely.

If he ends up trying the modified intake manifold route rather than the ITB's first, we'lll delete the IRIS altogether, and I suspect that 'dip' can be tuned completely smooth.

[SVXRide]

Bob,
Any chance you might be willing to offer the merge collectors for those of us fabricating their own SS headers?
-Bill

[RallyBob]

Originally Posted by dynomatt

Intake is stock, save that the MAF is gone, exhaust is standard headers with a 2" system joined at a y-pipe under the floor somewhere, then 2 1/2" out with one resonator and one muffler.

The intake cams have 10.0mm lift, with 230 degrees duration at .050.

The exhaust cams have 10.5mm lift with 236 degrees duration at .050.

I think these two combined factors *may* figure in.

We found a significant power increase on a standard engine with the 1.75" primary tube headers, into two 2.5" secondary tubes, merging into a single 3" main exhaust system. One can imagine that this exhaust further complimented....and was complimented by, the larger cams we now have.

FWIW, I think that 1.625" header might be a better choice for rallying, and a 2" merge collector tapering out to 2.5" secondary pipes will fatten up the torque compared to the road-racing setup that Jack's car runs. My own 'vintage' rallycar runs a relatively small header with longer primary tubes so I have a wider power band rather than a peaky one.

On your engine, you have larger cams, yet you are running an exhaust that is barely more efficient than standard. Perhaps this is the 'cork' that is not letting you extract full power from the camshaft upgrade. Overlap tuning from the increased duration while running with non-equal length factory headers will be virtually non existant.

Just my observations, maybe there's a bit more untapped potential still there.

[RallyBob]

Originally Posted by SVXRide

Bob,
Any chance you might be willing to offer the merge collectors for those of us fabricating their own SS headers?
-Bill

I wasn't planning on getting into business making them, if that's what you mean. Burns Stainless and SPD both make beautiful merge collectors, if somewhat pricey. I only make my own because I can't afford their's....

My own design is somewhat of a shortcut, but is infinitely easier for me to construct. The central 'cone' or 'pyramid' section is not an integral part of the collector, but rather is welded directly to the ends of the primary tubes. Then the collector is welded onto the primary tubes after the 'cone' is metal-finished. As seen here:



Note that the one outer collector section shown is merely tacked in place here for test-fitting. Normally I weld and finish the collector itself on a bench, then weld it to the completed header after-the-fact.

[SVXRide]

Originally Posted by RallyBob

I wasn't planning on getting into business making them, if that's what you mean. Burns Stainless and SPD both make beautiful merge collectors, if somewhat pricey. I only make my own because I can't afford their's....

Thus the reason for my question
-Bill