I posted this in the dyno forum but didn't get any responses... I was hoping that I could get a few quick responses from MEVI owners to share their experience with me and let me know if this is normal or if I have some motor problems.

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Well, now I want a BMW 540i 6-spd... this **** sucks... look at my numbers from Jan - May - July

Dec 2002: Stock Dyno (performed at DPE) 175HP, 186TQ
Jan: y-pipe + b-pipe (performed at DPS) 186HP, 197TQ
May: y-pipe + b-pipe + test pipe + cone filter (performed at TAG) 184HP, 188TQ
July: y-pipe + b-pipe + test pipe + cone filter + MEVI (performed at TAG) 180HP, 178TQ

I lost A LOT of midrange power with the MEVI it seems, and my peak HP/TQ has dropped significantly (especially since January... I was almost at 200lb.ft at the wheels with just y-pipe and b-pipe!!!)

Is it worth it? Track times will tell... but until I get a cool day to run, track times will suck and I will want a 540i even more... I really do not like the loss of almost 10HP and 20lb.ft of torque at the wheels in the midrange area. JWT ECU would at least extend the top end to 7000-7200RPM so that I can actually make my peak UP up there... MAYBE that will make up for the loss in midrange, but still... it kind of sucks to have such a huge drop! I will post this on the org to get the other MEVI guys' opinions.

So here are the HP and TQ comparisions, on separate graphs:





Incidentally, my stock dyno almost looks nicer (outside of top end)... haha



P.S. I will shrink the images if it really bothers people. Let me know. But I really hope that some of the guys with MEVI can help me out here.

 

You really won't notice real gains with the MEVI unless you get a ECU upgrade with the higher rev limiter. By the way, your stock numbers are real strong. I'm sure that your HP figures with your current mods and an ECU will be very close to 200 hp.

 

That's what I thought too... but as you can see... I gained a few HP and lost some torque. High-high end power is the only place that I gained.

 

and if u could take it to a 7200 limiter ur hp would gain right where it is supposed to see its gains with the mevi, and u'd be revving higher with alot more hp up top and ur entire hp curve would change

 

I'm willing to bet that the ambient temp difference between January and July is a big factor.

 

Yes the temp. was quite different and was indicated at the bottom of the graphs. However the correction factor should have evened it out... as you can see 0.97 vs 1.02

Even if I do get a JWT ECU, that doesn't change my midrange. Should I change the RPM switch to something other than 5000RPM? Would that get some of the midrange back?

Is that loss in midrange power normal with the MEVI? 10-20HP and 10-20TQ?

Also, shouldn't my top end pick up more than it did... and earlier (ie at 5000RPM)?

 

A few things that I am thinking.

That is a very high stock dyno, am I right??
Do you have the same wheels on for each pull?
Is your car running OK, any knock sensor codes?
From what I remeber from other dynos is that there is a mid range loss but still a peak HP/TQ gain.

A JWT/ECU will restore some midrange. From what I remember of a JWT/MEVI dyno, there was a gain of like 10 lbs of torque form 4K - 5K rpms.

I think something is wrong.

 

the stock dyno is high considering 190 at the crank with a typical 12-15% drivetrain loss with a manual. my opinion would be its the difference from dyno to dyno since it was 3 different places. edit

 

you dynoed at different places, a dyno is a tool for measuring changes, and they all read different. You should have gone to the same place all along if you want to compare numbers. There is no way that you lost hp and tq when you added a test pipe and cone filter. The place that you went to just reads lower.
That being said, yes, a MEVI does kill your mid-range, thats the trade off. A JWT ecu is not only used to raise the redline, it also helps restore the mid-range. These two items should be used together.

 

I lost 17 peak ft-lb but gained 2 peak hp with the addition of my mevi, but it was on different dynos so who knows. That dyno does seem a bit low, 7-9whp low I'd say.

 

Yes, the stock dyno does seem a bit high. I could not dyno at the same place (even though I meant to) through all the mods because DPE sold their dyno; DPS screwed me over so I boycotted them; so I am settled with TAG... however I might go back to DPS to verify that their dyno DOES read higher... because if it doesn't, then there might well be something wrong with my car.

KS was one of the suggestions. There are no CEL lights flashing at me. How else can I see if the KS might be bad? Or should I replace it anyway? I will be checking vacuum lines, etc to make sure that nothing is unplugged.

I do feel a bit better to hear that other guys with MEVIs have experienced the same massive mid-range loss... I need the JWT ECU I guess. BUT as everyone suggested, my top end should be higher than it shows, even though it is 25-30HP higher than before - again KS could be the main culprit?

What about PCV valve?

 

the dynos are not accurate cause the temperatures in those different months were different

 

A knock sensor alone will not trip a CEL. You could have the code without knowing it. Although I believe it's the dyno to dyno difference that is the problem.
As already stated, you had worse #'s with more mods on your second run which makes no sense.

 

That's why they correct the #s to SAE so that temp and other atmospheric conditions are cancelled out. Please stop posting in every thread because you rarely know what you are talking about.

 

 

I'm not impressed with their calculation of temperature correction factor. They corrected 39deg by 0.97 AND 64deg by 0.97?? That means they don't correct AT ALL for the 25 degree difference??? 25degrees would make a big difference in air density.

I wouldn't get all wound up in those dyno figures. Take it to the 1/4 and then make your mind up.

 

that was funny

 

it is funny, but it is true...gets on my damn nerves too.

 

someone put him on my ignore list, and it was not me. I think someone posted a link ignore me clik and I believe thats how it all happened

 

I completely agree. I noticed that CF was the same for the huge temp. difference between Jan and May as well... which makes me wonder if the CF in July which was considerably hotter (and more humid) was enough at all.

Track times will be the determining factor, but again, I have to run in similar conditions to what I ran back in April/May (which was considerably cooler this year) when I ran 14.59 with just the y-pipe, b-pipe and cone filter. Otherwise I might be disappointed again.

I will definetly make sure that I get to the track in Sept/Oct. Also, this weekend when I get my pulley installed I plan on dynoing at TAG and back at DPS as well (since they gave me the super high torque graph back in May).

But back to the MEVI dyno on top end, shouldn't my gains be much more drastic - as some other guys said? If the RPM switch is set at 5000RPM, shouldn't there be an immediate burst and not a dip and then just a gradual increase as my dynos show? Should I replace my KS either way? I don't know how to tell if it is bad or not. Also, what about PCV valve?

 

if you have a dip @ 5K, why not set it to 51K, also find out where does your engine buck up, (fuel shut off) and shift it right before rev cut off. Youll get max benefit out of it. My cut off is around 6715 in 2nd gear so as soon as I see 6600 RPMs I very quickly shift to the next gear to get max benefit out of this VI. At what RPM are you shifting?

 

 

My rev limiter is at about 6700RPM as well. I have bounced off it before when I first got the MEVI and didn't expect the car to move that fast up in those RPMs! I do plan on playing around with the RPM switch... and try 5200RPM and such. However, would bringing it down to 4800RPM or even way lower, to 4500RPM be bad? Would that help me get some of my midrange back and not affect the top end? How would that work out?

As for shifting... why would I shift into the next gear when I am on the dyno? When I drive on the track I would shift at about 6600RPM, since I don't have the JWT ECU. I haven't taken the MEVI to the track yet though.

 

The hp doesn't *rise* much when you're past 5k with the MEVI.

It just doesn't DROP like a rollercoaster....

 

Your numbers do look low, but I was disappointed by my numbers as well. From what I've seen the SAE correction factors aren't anywhere near what you could get on your own car under the SAE base conditions.

From my last dynos I ended up with
168.51 hp - 179.97 tq
http://forums.maxima.org/showthread....hreadid=233883

http://forums.maxima.org/showthread....hreadid=234818
-hype

 

 

That is correct - my numbers are low... and looking at past dynos (stock dyno and even the Jan dyno which was just y-pipe and b-pipe) those numbers were high... so how did I go from having a car that dynos high to a car that dynos low, after adding more mods that should do nothing but give more power (ie MEVI)???

That is why I am trying to determine if the problem lies in the motor or some part of it. Here's the recent history on my car:

49302 miles - 5 July 1999 - O2 sensor replaced
50329 miles - 27 Aug 2000 - O2 sensor, knock sensor, clutch replaced
56300 miles - 8 Sept 2000 - Spark plugs replaced
63733 miles - 21 Dec 2001 - Spark plugs replaced
65xxx miles - x June 2002 - Coolant temperature sensor replaced
91000 miles - today

All that was done before I owned the car. Now my car is at 91000 miles. I have not had to replace anything since I got it. Would any of the above need to be replaced in order to realize some of the missing performance back? What about PCV valve?

 

you keep mentioning the PCV valve, while is should be replaced through regular maintenance, it is no cause of power loss. If it is plugged it can make you burn oil or leak oil, but it won't make you lose power. You don't have fuel filter listed in there anywhere, has it been changed? It can cause a power loss if since you can't get enough fuel to the engine. Again, I think that this is dyno discrepancy. You can't compare numbers from dyno to dyno accurately, especially with the differences in correction factor noted above. If your car feels like it is running fine, then is most likely is, and I would not lose sleep over it.

 

Yeah try a 4800rpm switchover... and watch your numbers get worse.

I've posted 3 different threads backed up with EMPIRICAL DATA every time from back to back to back to back to back to back runs at the track. MEVI set at anything other than 5300-5400rpm makes your car SLOWER. I gain almost a full mph by setting it at 5300 or 5400rpm than i do at 5600 or 5200. Setting it at 5000 makes things even worse. I've done this three times at the track. Switching it back and forth making sure I'm not getting flukey data. The data are there, 5300 or 5400rpm is optimal. Anything less or more than that will waste your time.

As for the Correction factors temperature is only one variable. There are at least 2 others that come into play... barometric pressure and humidity. Just because there was a 25 degree temp difference doesn't mean squat unless you account for the other two factors.

That said, it doesn't necessarily mean their correcting formula is perfect. But 95emeraldgxe didn't even take correction into account. He just shot his mouth off like he does on every other thread without knowing WTF he's talking about and I'm getting tired of it so I replied to it.

 

I will be resetting my RPM switch up then thanks for the info