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Old 07-20-2001, 11:49 PM   #1
Patrick Olsen
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Thumbs up Initial data on MRT exhaust power gains

I recently installed an MRT header and mid-pipe on my '97 2.5GT, over 72k miles, all stock drivetrain (well, OK, I have a K&N filter). As of yet I have not installed the muffler, since MRT sent me the wrong one (I'm part of that bastardized 7-month-long group buy, and it ain't over yet!), so for now I'm using my stock 2.5GT muffler (which bolts right up to the MRT mid-pipe without a problem). (Is that enough parenthetical phrases for one paragraph?)

OK, let me be the first to state that this is not the most repeatable data in the world, but I think it's good enough to see some trends. Basically, the nearest strip is nearly 3hr away, and I don't have a G-tech, nor do I know anyone who does, so I came up with my own technique to check for any power gains or losses. With the stock exhaust and the MRT exhaust I've done a series of 2nd gear acceleration runs, one set from 2500 to 4500rpm, and another set from 3500 to 6000rpm. In both cases I start by holding the RPMs constant at the lower RPM, then floor it and start the timer, stopping it when I run through the higher RPM. For both sets of runs (stock and MRT) I've tried to find level pavement (kinda tough in New England, but all of the runs were done on the same couple of stretches of road), I've tried to do the runs in similar weather conditions (10-11pm, in the upper 50s/low 60s, dry), and I tried to keep the car similarly loaded (for the MRT runs I actually have about 1/4 tank more fuel, but I figure the extra weight is negligible).

With the stock exhaust I did 10 of the mid-range (2500-4500rpm) runs, which ranged from 2.63sec to 2.90sec, with an average of 2.824sec. I did 7 of the high RPM runs (3500-6000rpm), ranging from 3.43sec (probably just poor timing, but I left it in the calculations to be conservative) to 3.90sec, averaging 3.722sec.

With the MRT exhaust, thus far I've done 7 mid-range runs, ranging from 2.60sec to 2.73sec, and averaging 2.667sec. I've only done 3 high RPM runs so far, ranging from 3.35sec to 3.52sec with an average of 3.413sec.

Clearly I need to do some more data gathering with the MRT stuff on the car, particularly to confirm the high RPM data. I can truthfully say, though, that the car is noticeably quicker when I go to WOT at 3500rpm - it really leaps forward. On the other hand, I'm actually surprised at the improvement in the mid-range times, as the car didn't feel all that much quicker there. It could be it's not much quicker, if at all, between 2500 and 3500rpm, but from 3500 to 4500rpm it is quicker, so the numbers are kinda skewed. See below for what I might do to prove/disprove that theory.

Since the exhaust will be coming back off the car in a week-and-a-half or so to get the headers coated, there is an opportunity to do some more data gathering with the stock system. I think I might add a 3rd run of data, a low RPM band (maybe 1750 to 3000rpm or something like that). I'll also do some more timed runs once I get the actual MRT muffler on the car - I wouldn't expect much of a difference there, but I know (having heard one on a 2.5RS) that it will certainly sound better than the stock muffler.

Pat Olsen
'97 Legacy 2.5GT sedan
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Old 07-21-2001, 12:54 AM   #2
CosmoTheCat
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Hey that's cool. 2/10 off of the mid range is niiiice.
Just think.. 2/10s here, 3/10s there... in the 1/4 mile how many gears do you go through?
It adds up!

Quote:
for the MRT runs I actually have about 1/4 tank more fuel, but I figure the extra weight is negligible
Water is 10lbs/gallon? Gas is 8lbs/gallon? Is that right? So an extra 4 gallons of gas is about 30 lbs. Not much.
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Old 07-21-2001, 07:50 AM   #3
Patrick Olsen
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Actually, water is 8# and gas is 6#, so the difference is even smaller.

I really do wish I had easier access to a dragstrip, it would have been nice to get "real" before and after numbers.

Pat
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Old 07-21-2001, 05:25 PM   #4
m750
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Default 2 notes

There is a dragstrip about an hr from me, and I tend to go once every few weeks. I've only run once, and got a bad time, 16:01, I'll be sure to do run or two after I get it installed. As for real #'s, there is also a awd dyno opening up in the area in a few weeks, I'm going to try to have before and after runs documented... Who knows, I may eventually get it installed.
AO
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Old 07-21-2001, 07:52 PM   #5
Patrick Olsen
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All in good time, my young apprentice, all in good time. Just think, about the time you're installing yours, I'll be taking mine back off so I can get it coated. So I'll have to go back to having a plain ol' slow Legacy for a week or so - torture!

Pat
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Old 08-16-2001, 08:57 PM   #6
rx
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Patrick - I can assure you it will be better with the proper muffler! Can't wait to see your results after you've got it on.

The standard muffler has WAAAY too much backpressure and is counteracting what the headers are supposed to be doing...

Even without a full exhaust system, replacing the muffler alone helps.

The less backpressure after a tuned length header, the better.

With a ganzflow style inlet, and full MRT exhaust system on my 2.0 litre NA Impreza RX, I have taken over 1.5 seconds of my o-100 time. So now I do it in approx 8.5, as opposed to 10.1 ! I'm nearly as fast as a standard RS now with half a litre less capacity.

What's more, it's still very retarded throughout the rev range, and is running way rich up top, a Uni Chip piggyback computer will resolve all these issues. So there's quite a bit you can get out of these motors with a proper exhaust on.
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Old 08-17-2001, 02:34 AM   #7
subysouth
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Default I hate to ask

But could any of you with the mrt systems tell me how much it ended up costing delivered? thanks
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Old 08-17-2001, 08:48 AM   #8
Patrick Olsen
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It was about $625 I think. The initial group buy deal was supposed to be $420, shipped, so we all paid that. A couple guys paid to have their exhausts shipped direct to them, I'm not sure what they ended up paying. The rest of us had a batch shipped to CA, then repackaged to ship to each of us individually. The cost to do all that was split equally, and was right about $205 each (I think). So it was way more than initially planned, but I think we still came out a bit ahead of what distributors here in the US sell the kit for.

Pat
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Old 08-17-2001, 04:51 PM   #9
subysouth
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Default Thanks Pat

Thats seems like an excellent price. The systme for my Legacy would be about 450 usd from MRT's price list but I was really worried about shippping costs and MRT website doesnt do anything to help these fears. Maybe another group buy..... anyone?
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Old 08-17-2001, 07:47 PM   #10
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Quote:
Basically, the nearest strip is nearly 3hr away, and I don't have a G-tech, nor do I know anyone who does, so I came up with my own technique to check for any power gains or losses.
I'm thinking for all this testing effort, you should probably just BUY a G-Tech.
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Old 08-18-2001, 10:30 AM   #11
Patrick Olsen
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Hmmmm, let me think about this. $140 for a G-tech, which surely is more accurate than my finger on the stopwatch vs. my absolutely free finger on the stopwatch. I'll stick with free, thanks.

Also, correct me if I'm wrong, but doesn't the G-tech do 0-60mph and 1/4mi times? If so, that means my times would be affected by launch technique, which is something I was specifically trying to take out of the picture.

If I already had a G-tech, I'd certainly use it, but I'm not going to spend $140 to get one just to use it a couple times then stick it on a shelf.

Pat
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