JRock

Clearly being a turbo car, I would think easing the intake and exhaust paths for the engine would easily improve the power it puts down as well as smoothing out the hp/torque graphs.

Does anyone have clear dyno proof of before and after of a stock Evo versus one with, for example, RMR's intake kit, IC piping kit, and turbo-back exhaust kit?

Perferably someone without any ECU mods and someone other than RMR that sells it.

Those are some of the first mods I'd plan to do but every once in a while I come across a post from someone claiming the mods actually LOSE power or that their stock Evo beat one with those mods.

My guess would be driver error, as intake and exhaust mods on a forced-induction car should never lose power like they have the possibility of doing on a stock naturally-aspirated car.

Thoughts, opinions, dyno charts?

Alfriedesq

iTrader: (6)

The exhuats makes 25 - 30 hp on a stock car id you turn up the boost - (when you remove stock muffler and cat boost falls about 1 - 1.5 psi)

The intake makes little or no power gains

The i/c pipes make no gains - but inprove "feel" as you loose the bulging in and out of the stock hoses and it looks better

Noize

iTrader: (24)

When you say"turn up the boost", is there a way to restore the default values without an MBC or EBC? My WRX picked up boost when I put on a less restrictive exhaust. The Evo loses it? Strange.

JRock

Yeah, why would it lose boost level?

Also, when I say turbo-back I would still be using the stock cat.

I thought the TB exhaust dyno'd ~25hp (stock cat), the intake another ~10hp, and the IC piping just smoothed things out and improved response (cut lag a little). So I thought easily another 35hp from those mods.

rollo

Thought: heat. I have the RMR intake on my car, and as it got hotter out (ambient temps) there did seem to be a difference. This is a problem, obviously, with any car (because hotter air = less dense air) but it's exacerbated when you throw in forced induction, and the problem also occurs with an airbox, but less so due to the airbox being less susceptible to engine heat. That's why a forced induction car feels so much faster at 50 degrees than it does at 90 (well.. both my (supercharged) Corrado and the Evo anyway).

The solution of course is to try and get as the air entering the intake to be as cold as possible. RMR offers a half scoop/half vent that funnels air directly on to the filter. Personally, I put the stock air intake tract back in, and made a heat shield. Kinda ghetto but it does seem to make a difference. I picked up a couple of remote sensor thermometers but haven't had a chance to try them to see what kind of temperature drop the heat shield causes.

Other than the rather 'analogue' density issues of hot air, there's also the question of how the ECU reacts. The Evo does have an intake air temperature (IAT) sensor so presumably when the air coming in reaches a threshold temperature, the ECU starts compensating - by reducing boost levels, for instance. Without a boost gauge, I can't confirm or deny that, but it is common practice. That would obviously have an enormous effect on performance, and may well be responsible for the drop in power that people are seeing - the IAT threshold has been reached by the car with the open filter, but not by the airbox car.

As far as the other mods, I'd agree - anything which smooths and eases intake and exhaust, especially on a car running 18 pounds of boost, should enhance performance. Although there is the question of the stock cat restricting the exhaust flow. The stock plumbing could definitely be improved upon - it's pretty twisty, especially the IC pipes.

Just a few thoughts. I kept the intake on my car cos it seems to improve drivability in lower rev range - power sooner, rather than more power - and the response seems a little better. I know 'seems' isn't much to go by, but it's all I have right now. It also makes the stock BOV sound awesome, which I know is a dumb reason to keep it, but I wanted to try my hand at a heatshield anyway.

JRock

Yeah, hearing the BOV and turbo more are one of the reasons I want the intake, but of course performance is still the number one reason.

So perhaps the RMR intake with a heatshield would work pretty well?

I don't want the scoop thing because I want the car stock on the outside, and other reasons.

rollo

Your call - depends how hot it gets in MD I suppose

I think any intake would have the same problems and benefits, but I may be wrong.

I'm also gonna take a look to see how easy it'd be to get some kind of ducting to take air from the bumper or the undertray (easy to cut a duct into the undertray) to the filter.

The heatshield wasn't easy to make, but it wasn't exactly rocket science either. I may make another more 'polished' version though. I bolted it onto the airbox mount. It's definitely worth doing - the Mitsu factory SCCA Pro-Rally Evos have a custom hood with a NACA duct funnelling air onto an open filter with a CF heatshield separating that corner from the rest of the engine. Good enough evidence for me.

DRC Imports

iTrader: (38)

Hey JRock, sound like I didn't get here in time to answer your questions but I do sell RMR products. With all you are looking at, I can work out a nice deal for you. Let me know. Thanks bro !

Alfriedesq

iTrader: (6)

The evo looses boost when you remove the stock muffler becuase of the flap inside the muffler which raises up the boost when you add a MBC or EBC you can raise the boost back up to stock levels and thats why you see big gains

SilverEvo8owner

iTrader: (3)

I have the RMR intake and yes i can tell a difference between cold and hot days, but i could also tell with the airbox

I notice gains with the butt dyno and i think that throttle response is better.

Im very happy with the RMR intake

Also i removed the slats that were in the hood

Heat seems to escape alot faster

JRock

Hmm, maybe someone with the resources (and time) should look into making and selling a heat shield that fits around the RMR intake, since it seems a fair number of people have it. Might be a good way to make a few bucks and help out fellow Evo owners at the same time!

As far as sucking air from under the car you need to be really careful because if you run through standing water you risk hydro-locking your engine. I generally just make a simple rule to stay away from anything like that to avoid the risk and time it takes to do it right.

DRC Imports - I appreciate the comment but I don't even have an Evo yet, so I'm a little ahead of myself as far as mods go! \

I will keep you in mind though when it comes time to order the mods.

As far as heat goes, within six months I may be in Phoenix, AZ, so whatever happens temperature-wise in Maryland is kinda irrelevant in that comparison!

dilow

iTrader: (2)

Correct me if I'm wrong, but...
I have an intake, ic piping, downpipe, and exhaust from RMR and they forgot to send the piping from the turbo to the IC. So I installed everything except for that. Drove the car around and it was good. Now when the rest of the RMR IC piping finally came and was installed, the turbo seemed to spool a later and thus seemed to have more lag. I was thinking that it was because the piping was bigger, so it took more time to spool up the turbo. Anyway, from the turbo to the IC, I changed the piping back to stock and seemed to build boost quicker. Any thoughts?

DRC Imports

iTrader: (38)

Sorry JRock, didn't notice you don't have an Evo yet. No problem !

JRock

Hey np. I wish I DID have my Evo already.

50cal

iTrader: (1)

So if I just bolt on a cat back exhaust and downpipe (stock cat for now), no boost controller........I'm going to lose power or just won't realize as much gain without a controller?

Interesting.