[ilivas]

Originally Posted by Black-STi

stock cams have a steep drop off in power after 5100rpm I believe...

not neccessarily a power drop off, it's a torque drop off. A huge one at that. Typically we would want our torque curve to stay trhough the upper rpm range which is what cams do.

With increased upper rpm torque, you also get an increase in upper rpm hp.

I'm running the DPR 272/272 cams.

[Tortfeasor STi]

Originally Posted by SNE2040

It's not cost efficient to do anything besides basic bolt ons on an STi because of the motor design. If you want a hell of a lot more power, buy an Evo or a Supra.

Depends on what you mean by a lot more power. You can do some decent turbo swaps and make good power without touching the engine, as many members have. But you can make 400+ hp on the stock motor with a safe tune and pump gas with a turbo swap.

I do agree though that if you are looking for dyno queen numbers a supra or a domestic will suit your wallet better on a $ per HP basis.

[WRX4ME LE 482]

Originally Posted by SNE2040

It's not cost efficient to do anything besides basic bolt ons on an STi because of the motor design. If you want a hell of a lot more power, buy an Evo or a Supra.

Not the first time Ive heard that. What is it exactly about the design of this engine that limits it so?

[Sinister redlines]

Crawford, I have to disagree with your theory. The avcs does advance the cam but does NOT add duration. With aftermarket cams there is higher lift and longer duration in turn more air and fuel may enter. Advancing the cams help with powerband placement. Not to mention the STi heads have a horrible exhuast port desighn to help burn the exhuast gases better in turn lower emissions.

How do I know you ask, I have a flowbench and the #'s dont lie.... Sure its possible to make great power with stock peices BUT you know full well that the potential is much higher with good cams and a balanced port work.

[Black-STi]

Originally Posted by Sinister redlines

Crawford, I have to disagree with your theory. The avcs does advance the cam but does NOT add duration. With aftermarket cams there is higher lift and longer duration in turn more air and fuel may enter. Advancing the cams help with powerband placement. Not to mention the STi heads have a horrible exhuast port desighn to help burn the exhuast gases better in turn lower emissions.

How do I know you ask, I have a flowbench and the #'s dont lie.... Sure its possible to make great power with stock peices BUT you know full well that the potential is much higher with good cams and a balanced port work.

....and the port and polished heads you did for my car is a work of beauty! Can def see the increased airflow from the reworked heads and cams, even at idle....

[SNE2040]

Originally Posted by WRX4ME LE 482

Not the first time Ive heard that. What is it exactly about the design of this engine that limits it so?

Well like others stated, you need 4 cams and you gotta drop the motor. Also our oil feed system kind of limits us from revving high.

All i'm saying is that it's a lot cheaper and easier working on an Evo or a Supra.

[boost_happy]

I've had 10 sec mustangs in the past and of course with a pretty aggressive cam, supercharged, etc. I must say that daily driving wasn't the greatest thing in the world but when I was in race mode, it was great. But with the STi crowd daily driving is pretty normal, so sometimes comfort and ease of driving sometimes out weighs the performance increase with cams. And mine is a daily driver and just the peace of mind that it drives like a normal car but rips when I want it to is great. Just my .03 cents.

[ilivas]

Originally Posted by SNE2040

Well like others stated, you need 4 cams and you gotta drop the motor. Also our oil feed system kind of limits us from revving high.

All i'm saying is that it's a lot cheaper and easier working on an Evo or a Supra.

the only thing keeping us from revving high is an oil pump. Those are cheap.

[escos]

Over here one of the first mods anyone does when they get into their motor is replace the stock STI cams with the Spec C cams, and the stock turbo with the spec c ball bearing turbo. The mod is good for about 40 hp. I've always wondered how much of that is the cams...

[Sinister redlines]

Originally Posted by ilivas

the only thing keeping us from revving high is an oil pump. Those are cheap.

Not exactly, the oil return can be an issue due to the inherant desighn of the boxer the heads have a poor drain back area. This is why the serious racers use a dry sump system where there are several pickup points.

However for a street car one of the best mods is oil cooler or simply increasing the oil capacity in the form of a custom oil pan (there are a few in the works like moroso) or simply a larger remote filter with the cooler.

Dont get me wrong, you are correct with the need for a good oil pump like cosworths or a shimmed one (your preference, I personnaly would rather have the cosworth).

[ilivas]

Originally Posted by Sinister redlines

Not exactly, the oil return can be an issue due to the inherant desighn of the boxer the heads have a poor drain back area. This is why the serious racers use a dry sump system where there are several pickup points.

However for a street car one of the best mods is oil cooler or simply increasing the oil capacity in the form of a custom oil pan (there are a few in the works like moroso) or simply a larger remote filter with the cooler.

Dont get me wrong, you are correct with the need for a good oil pump like cosworths or a shimmed one (your preference, I personnaly would rather have the cosworth).

We're going to find out pretty soon in my own build. My builder has been talkting to Ron at Axxis, and Howard at AR Fab. The only thing that's been reccommended for my 8k rpm rev limit is AR fab's modded oil pump (from further inspection it looks like it was shimmed and ported a bit), and AR fab's harmonic balancer. Ron at Axxis reccommended their own cross-drilled stock crank. We opted for just a simple polish and balance though as reccommended by Howard.

These rpms arent going to be held very long as it's a drag car, not a road racer.

We suspect that any higher than 8k we might need to move to a dry sump.

[Sinister redlines]

Originally Posted by ilivas

We're going to find out pretty soon in my own build. My builder has been talkting to Ron at Axxis, and Howard at AR Fab. The only thing that's been reccommended for my 8k rpm rev limit is AR fab's modded oil pump (from further inspection it looks like it was shimmed and ported a bit), and AR fab's harmonic balancer. Ron at Axxis reccommended their own cross-drilled stock crank. We opted for just a simple polish and balance though as reccommended by Howard.

These rpms arent going to be held very long as it's a drag car, not a road racer.

We suspect that any higher than 8k we might need to move to a dry sump.

Dont get me wrong I am sure your build will be very strong as the names you mentioned have great reputation, I am simply stateing that there are other factors that will increase the longevity of the engine. Even a accusump system is a great investment and can also give you some added protection. I just feel the oiling system is over looked in big builds. Most people dont realize that engine oil is the number one cooling agent in a internal combustion engine. As it is in direct contact with all the rotating parts where as water is a surrounding medium.

[ilivas]

As this is a built motor, longevity is a 2nd priority concern. Hopefully, the inherent piston slap from forged pistons will wear it out before the oiling (or lack there of) will . I will do an oil cooler when more funds become available.

Doing a dry sump is just too expensive for me.

[Crawford/I-Speed]

Originally Posted by Sinister redlines

Crawford, I have to disagree with your theory. The avcs does advance the cam but does NOT add duration. With aftermarket cams there is higher lift and longer duration in turn more air and fuel may enter. Advancing the cams help with powerband placement. Not to mention the STi heads have a horrible exhuast port desighn to help burn the exhuast gases better in turn lower emissions.

How do I know you ask, I have a flowbench and the #'s dont lie.... Sure its possible to make great power with stock peices BUT you know full well that the potential is much higher with good cams and a balanced port work.

Your opinion is welcome, that’s what forums are all about. But you saying we know full well that the potential is much higher with good cams is simply “not true”. I think it goes without saying that we have the resources to run any cam we choose in our Time Attack car… Our goal was to be the fastest Time Attack Subaru in the US and we have achieved that goal using stock OEM cams in our motors.

If we were to go drag racing, we would choose an aftermarket camshaft to place the powerband in a narrow area of the power curve which would match the gear ratios in the tranny.

Our dyno computer has a massive database that has been collected over years of testing all the different components available on the market. This hard data as well as what we’ve learned at the track is how we choose the components used in our motor/cars.

As you said, the numbers don’t lie... Do be wary of sales people though

[Sinister redlines]

The point I was making was that larger cams increase lift and duration, vs avcs advance the timing of the cam. I respect your engine building skills dont get me wrong. I just believe in a street car larger cams are benifitial (by this I mean in the 272 range not 280+).