[zx10guy]

I'll just cut to the chase. Been having a back and forth on a different forum where someone was claiming significant horsepower gains by just reducing exhaust restriction on the current gen Toyota Corolla with the M20A engine. My stance was that any aftermarket exhaust system would only be for sound, aesthetics, and maybe weight savings.

So he produced a dyno chart posted on 2JRacing's FB page showing by adding an intake, headers, less restrictive mid pipe, and cat back that they were able to get 30WHP gain on the factory tune. To me this doesn't pass the smell test as that's huge for what amounts to be an econobox that is naturally aspirated. I also looked deeper into the dyno run where they claim the base line run put the horsepower at 151whp. That didn't seem right to me assuming a 20% loss would mean they're claiming the stock setup is at 189 crank HP. The factory rating is 168 HP. With their mods, their dyno run shows 180whp which would translate to 225 HP at the crank. So in essence, this tuner is claiming a 33% increase in just bolting on an intake and exhaust over the factory HP number or 20% over their measured stock baseline with no tune.

Something doesn't add up. What are your thoughts?

[9krpmrx8]

Seems like BS to me, even on a custom tune I would doubt it. Dyno settings are easy to manipulate, so trusting a dyno sheet is pretty dumb.

edit: a Quick search shows that OV tuning did get 27WHP out of a stock M20A Corolla though on a custom tune.

[Soterios]

I don't really buy any of it. Dynojets read notoriously high anyways, but those gains for breather mods on an NA four cylinder are ... too much.

[Tambohamilton]

So many ways to fudge, falsify or void dyno results. For the reasons you stated, I'm also not buying it!

[heavyD^2]

I have a hard time believing unmodified stock ECU maps would dump the amount of extra fuel required to net addition of 30 whp on a little NA 4 cylinder engine.

[tdott]

Does it matter?, it's a corolla.

[Humdizzle]

Dyno readouts can be fudged by any company.

1/4 mile and 60-130 times can't. i'd be curious to see what kind of trap speeds guys are running with their setup compared to stock

[RM7]

You know what they say, if it's too good to be true, it was probably tweeted.

[ShocknAwe]

This is most likely done by cherry picking results by doing a nonideal low read baseline and perfect conditions and highest read after mods.

Having done similar mods on past NA cars, including Japanese makes, I call total BS. Most I ever saw from this kind of thing was ~15hp.

[Suds]

They turned that thing into a beast!

Ok, I really doubt a near 20% gain with bolt ons and no tune.
They should have bought something with a 2.0t it would of had way more torque and hp to start with, then throw a tune on it, done!

[Mingwan]

untuned? kind of hard to believe that.

[RM7]

A few things to think about. On NA engines, displacement, compression ratio, max RPM (helped out by lightweight parts) and things like that determine the maximum power. A good way to figure this out is to look at same displacement and similar and different compression-ratio engines and see what they make. That usually gives you an idea if it's possible or not. Also, aren't these more limited by RPM, being NA? As in what else could possibly be going on here? I suppose that air induction could be crazy restrictive, but that just doesn't make any sense with all the other parameters involved.

I don't believe there would necessarily be a 20% loss, maybe if it was a RWD or especially an AWD vehicle (20% is much closer to AWD figures, my RWD only loses about 12%). Being FWD, that Corolla probably only loses around 10%. The engine is probably up around 200hp according to the chart, assuming all of this. Just a real quick cursory look shows small displacement 2.0-ish type engines having to rev to around 8K to make 200hp. Yeah, it's really fishy.

[zx10guy]

Originally Posted by 9krpmrx8

Seems like BS to me, even on a custom tune I would doubt it. Dyno settings are easy to manipulate, so trusting a dyno sheet is pretty dumb.

edit: a Quick search shows that OV tuning did get 27WHP out of a stock M20A Corolla though on a custom tune.

Unless this happened recently, OV Tuning wasn't able to come up with a tune for the M20A. There's a long thread on Toyota Nation where OV promised to come out with a tune. Then they said they were close. Then gave up.

[zx10guy]

Originally Posted by JamesNoBrakes

A few things to think about. On NA engines, displacement, compression ratio, max RPM (helped out by lightweight parts) and things like that determine the maximum power. A good way to figure this out is to look at same displacement and similar and different compression-ratio engines and see what they make. That usually gives you an idea if it's possible or not. Also, aren't these more limited by RPM, being NA? As in what else could possibly be going on here? I suppose that air induction could be crazy restrictive, but that just doesn't make any sense with all the other parameters involved.

I don't believe there would necessarily be a 20% loss, maybe if it was a RWD or especially an AWD vehicle (20% is much closer to AWD figures, my RWD only loses about 12%). Being FWD, that Corolla probably only loses around 10%. The engine is probably up around 200hp according to the chart, assuming all of this. Just a real quick cursory look shows small displacement 2.0-ish type engines having to rev to around 8K to make 200hp. Yeah, it's really fishy.

Looking at the dyno chart, they don't get to 8k RPM. Looks to be 6.8k. Also, increasing the flow with a CAI doesn't take into account the intake manifold which is still the restrictive stock unit nor have the heads been flowed/ported.

I just wanted to see if I'm not some sort of dinosaur where there was some magic potion being sprinkled on these 4 bangers that would make these gains plausible.

[RM7]

Originally Posted by zx10guy

Looking at the dyno chart, they don't get to 8k RPM. Looks to be 6.8k. Also, increasing the flow with a CAI doesn't take into account the intake manifold which is still the restrictive stock unit nor have the heads been flowed/ported.

I just wanted to see if I'm not some sort of dinosaur where there was some magic potion being sprinkled on these 4 bangers that would make these gains plausible.

The reason it doesn't make sense is volumetric efficiency. If Toy is artificially restricting it that severely from what it's normally capable of, not talking any special sauce, just regular flow into the head, then you are lugging around a whole bunch of extra engine everywhere that you don't need, impacting efficiency significantly. Again, it just doesn't add up.

[roastbeef]

why is this surprising? its a turbo car choked up with emissions crap and they remove all the restrictions.

[zx10guy]

Originally Posted by roastbeef

why is this surprising? its a turbo car choked up with emissions crap and they remove all the restrictions.

There is no turbo. The engine in question is a Toyota M20A naturally aspirated motor.

[yco]

actually its a pretty nice engine that using both port and direct injection with whopping 40% thermal efficiency aside you cant get 30whp by changing here or there without remapping out of a 2.0L engine..

few ways to achieve such results by using a lower gear on stock run and higher with bolt ons.. you can multiply kW by 1.4 not 1.34 like it should be.. or different fuel.. i guess the half of the gain d be plausible.. or after remapping the engine it can produce 50% more power than Toyota engineers could achieve which then these guys deserves a trophy..

[zx10guy]

Originally Posted by JamesNoBrakes

The reason it doesn't make sense is volumetric efficiency. If Toy is artificially restricting it that severely from what it's normally capable of, not talking any special sauce, just regular flow into the head, then you are lugging around a whole bunch of extra engine everywhere that you don't need, impacting efficiency significantly. Again, it just doesn't add up.

Totally agreed. And one of the comments I made to the fanboi that the numbers are fudged or the Toyota engineers don't know what the F' they 're doing.

[roastbeef]

Originally Posted by zx10guy

There is no turbo. The engine in question is a Toyota M20A naturally aspirated motor.

oh i see. i thought i read "downpipe" somewhere when i skimmed through it.

i rented a corolla a few years back when i was in colorado for a wedding. the combo of that car plus the altitude was almost dangerous when trying to merge onto the freeway. my foot was through the floor getting on the on-ramp and it had a hard time reaching the speed of the flow of other cars in a reasonable amount of time. it was that terrible.

[OkieSnuffBox]

Originally Posted by 9krpmrx8

edit: a Quick search shows that OV tuning did get 27WHP out of a stock M20A Corolla though on a custom tune.

Orange Virus and Good-Win Racing are notorious for claiming gains with exhausts and tuning that can't be replicated by anyone else. "By this exhaust and our tune and pickup 30whp." Then when someone does, back-to-back on a different dyno they see 15whp.

Take that as you will.

[Dog Face Pony Soldier]

I was just watching a YouTube review on the turbo-4 Mustang and was surprised to learn Ford says the car gains 20 HP by just using premium fuel. Not WHP and a different car, but to me this does provide some perspective.