Does the overpipe really make a difference?

[SirBrass]

These parts won't add much power thanks to the fact that the stock tune gets timing pulled on 91 from the get-go (yes folks, this car knocks on pump gas on stock tune... it was designed for 93 octane minimum, not the mandatory crap gas those of us in AZ, CA, and NV are forced to put up with or go E85).

Also, looking at peak HP gains for this part is just stupid. You're looking at the wrong thing.

Even Nameless says the OP/FP won't add much if any peak HP, but what it WILL do is allow a tuner to be able to more thoroughly eliminate the torque dip.

With a tune alone on stock exhaust the tuner is unable to eliminate the torque dip. It can't be done on stock exhaust design. You'll need both the tune AND the exhaust components.

And getting rid of that torque dip alone is worth the parts compared to leaving the dip and only increasing peak HP/TQ.

Look at the TQ curve, not peak HP numbers. TQ is the real power measurement, as HP is merely TQ * RPM * conversion factor.... that is, HP is purely a function OF TQ applied at the wheels.

[Shagaliscious]

Originally Posted by s2d4

So what is the point of tuning then?

What he is saying is that you can't dyno a stock car, then put the over pipe on AND tune it, and dyno it again. Because the numbers would be skewed towards the over pipe + tune. This is the method most companies use to skew the dyno numbers in their favor.

[FrsDuke]

Originally Posted by STV3

Turbo + Stock tune = BOOM

It was sarcasm. My point is untuned before and after is not always possible or meaningful. It is never the ONLY meaningful comparison.

I think the most meaningful comparisons are tuned vs tuned.

[SirBrass]

Originally Posted by FrsDuke

I think the most meaningful comparisons are tuned vs tuned.

I think I could, in many circumstances, agree with this.

[kuhlka]

Originally Posted by Wise

I'm looking at getting the Perrin exhaust system and I'm weighing up whether to get it with the over pipe, or to just get the catted front pipe and the cat back components.

My question is, does the overpipe really do anything? Perrin quotes a 3rwhp gain but that's pretty negligible on a dyno and wouldn't even be noticed when driving. How does it increase flow being such a small part of the system?

Does anyone have any experience comparing these two setups?

Do you want low-end torque or high-end horsepower? From what I've heard it's a toss-up, but the stock OP gives better low to mid-range torque. Aftermarket OP's are great for forced induction, though.

[fooddude]

Originally Posted by s2d4

So what is the point of tuning then?

For yourself and for your personal car/goals

Of course tuning is a good thing..

I just meant that marketing hype of parts with a tune afterwards to get the most out of it, isn't really all that great for seeing how much hp a certain part can truly make on its' own, out of the box and is a bad comparison b/n parts ..ie: gloating that "my new part can make this much hp...seeee (but only after days and days and days of tuning" ..did that make sense? .

..another example, maybe a bit exaggerated: My Op can make 60whp; after I added a turbo kit! lol ..similar, because the tune itself is like already adding another part since tunes themselves can provide much more power.

[jc1993]

Originally Posted by StormTrooper

I love it when people say that na is useless and to just go FI like spending $1500 is just a few cents away from the 5k you'd need for a turbo setup.

35hp while it isnt a ton will be noticeable in a light car.

^ agree! i personally would go with innovate sc for FI that way i can keep all my na mods!!! that would be way later on thou

[350matt]

hang on chaps

every component needs a tune to optimise the engine and make the use of it

the issue is the stock tune is quite frankly rubbish, yes you need some safety margins in there but its actually pretty compromised as you can get 12-14 bhp just on the tune

so what we really need to see in these comparisons is the stock car tuned vs the part in question fitted and tuned / optimised


that way you're comparing just the effect of the part - I mean if the exhaust part lowers back pressure that allows more spark then thats a valid effect as its not on the table otherwsie

[StormTrooper]

It's more of a gas flow both volume and velocity not back pressure.

Where that comes from is too large of a pipe up front slows velocity and hurts exhaust gas scavenging.


I do agree about the tuned comparison, the only issue is you'd need a skilled impartial tuner.

[kiichiro]

If you're hesitating on forced air, cool, I can dig that

Do not doubt the value of e85 if you stay na

[NYCsubaruBRZ]

we will see. i went the cheap way with a dc sports overpipe. hope it fits. getting it retuned after. ill let u kno if there is gains. right now im ecutek tuned, injen intake, ap headers, j2 downpipe & catback, 3pc light weight pulley kit. i wanted to find a place (before i re-tune) in long island to get the tb p&p but i cant find a shop.