PSI/Aftershock NA project dyno numbers
 

Someone on another board asked me to post this up here as apparently a number of people here wanted to see dyno results.

This is on a 4G69 powered ralliart. We dyno'd the car stock at 138whp. We installed an aftermarket header but the car lost 2-4hp. Looking at the stock unit I am of the opinion that unless many hours were spent developing an aftermarket piece it's unlikely to make any significant gains. So it was removed and we added a complete 2.5" exhaust system - high flow cat to the tailpipe. Added an underdrive pulley and a weapon R short ram air intake. Also added some hardware to retune the vehicle.

Sum and short of it, a gain of 30whp and lots of extra torque.

Ok, So below in the first one you see the best run. The factory ECU has a tendancy to learn a little as we go so I did a number of power pulls with the tuned map. The worst from the bunch was 168whp so there wasn't a huge difference.

http://www.redliners.ca/ralliart1.gif

Next I removed the piggyback 's tuning by zeroing out all the values. It put down 160whp fairly consistently 2-3 runs with the same numbers. Then I reloaded the tuned map and it put down 170 again. Just proof that the untuned numbers were not being caused by engine heating. That's about as consistent as I can do it and the best I could do with the 1h of rented dyno time.

http://www.redliners.ca/ralliartc.gif

Other fine details I modified both images to remove the car owner's license plate number. No other changes were made. I also scaled the horsepower and torque graphs to show the exact profile of the torque and horsepower numbers. I'm not exactly sure why the stock tune is so lumpy on the torque but it did it every time. I suspect it just wanted the extra fuel I added in the tuned map.

At another time we tried to see how much power was gained by adding an aftermarket NA header but the car lost power so the part was removed and obviously not included in this test.

which header was it?

What piggy did you use?

I didn't see a brand name on it. It was a simple 4:1 design - nothing to write home about. Badly designed header and I could tell you without booting up a CAD program whomever designed it has no idea about harmonics. Maybe I'm just bitter because I sliced myself open on this razor sharp bracket they'd welded on. If I had to guess I'd say it's OBX but I have no idea. I'll ask.

^hopefully that wasn't a rrm header because i got one sitting in my basement.

Yup it's a RRM header

Having thought about it I don't think finding and reporting the brand name is that important. I'm sure the company who made it tried very hard to make a part that improved the performance. Unfortunately designing NA headers is a task for someone with an engineering background.

There are a number of things you do not want to do on an NA engine. I just looked at the header again. First, the size of the exhaust port is too similar to the exhaust port on the head. Some people "port match" things like this without understanding exhaust reversion and that commonly results in a loss of power.

I remember a few years ago someone brought me an intake manifold they'd "port matched" and they were pissed off when I told them it would likely hurt their power. We dyno'd before and after. Guess what? 8whp gone!

Mitsubishi wasn't stupid when they ran cylinders 1&4 and 2&3 together. They knew that from the design and operating range of the engine they wouldn't have enough space to take care of the 2nd and 3rd order harmonics yet they wanted to produce good bottom end torque. So they did a 4 - 2 - 1 header. These runners are too short before the collector. That hurts power because the scavaging effect is lost. I have some fairly involved CAD programs for designing stuff like this.

Finally the collector which is another key area for making power. This one is just 4 pipes that end. No proper merge, nothing special. I'd have to look again but I think even mitsubishi did a decent job on the stock piece.

Now I understand he paid only about $350 for the part and there is no way to design and build a proper one for a price like that but if you wonder why it doesn't perform there are reasons. I would rather offer a part at twice the price that works than one for 1/2 the price that doesn't.

If you lost HP then you obviously dynoed it. Care to share those dynographs?

i dont get it. i remember a couple guys on here doing dynos before and after and they recorded about +10 hp on the header. something seems wrong here.

there was only one person claiming it was RRM, and it's not the guy making the HP loss claim. draw your own conclusions much?:lol:

I can print them as soon as we do the clutch on the turbo project. Unfortunately it's a little too powerful for the stock clutch... I didn't touch the tuning with the header so maybe that would have made a difference. The stock piece looks fairly good to me.

I don't know why others would have seen a 10hp gain from a header. That's quite a lot for a piece that's not bad from the factory. If the ECU was reset and it had learned to pull a lot of timing from an old bad tank of gas that could explain a 10hp gain.

I don't know - my main focus is in making power on this car. I did not spend a lot of time trying to figure out why the other piece lost power. I ripped it off and put a stocker on.

I honestly do not know who made the part. It really looks to me like OBX quality materials and the TIG welding looks like their work. I don't own a Mitsu nor do I have a lot of experience with parts made by others. When the customer comes to pick up the car I'll ask where he got it for my own info.

i know it's an RRM header, cause this my friends car and he had bought the header used off of someone else, so this is how i know

I would like to see proof of the power loss...... I would change my header but i no longer have any of my stock components. I am soon going to get my dyno sheets going..... the more i tune it the more i believe i can get 210+ WHP.... and still have alot of room for more power..... I got my ways....{thumbup}

thats BS, I gained 6 hp over the dp with RRM's header, and the DP and the Injen CAI combined gave me 167 hp and 166 tq

With underdrive pulley it gave 171 hp

with RRM's header, that number increased to 177 hp with the header and the same mods, consistent mind you, different days it gave the same number or close

it even increased more this past couple of weeks in which I added some go fast tools...but Ill keep that to myself