Power loss
 

Hey guys I'm wondering why I'm losing power top end. Car builds good power til 6950-7000 rpm and then it plateaus til about 7500 then I lose 5hp til redline. Current mods.

Stillen g3
Motordyne manifold
Fi lth
Custom 2.5 exhaust h pipe with magnaflow muffler
4.08s
Uprev tune

Tuner says could be exhaust but I have no idea why it's happening. Any help will be appreciated.

http://farm8.staticflickr.com/7270/6...744df90b_b.jpg

u are losing power after 7500?? prolly because your car is outta the powerband at that point. and secondly losing 5whp till redline is really nothing to worry about

I use to make power til 7900rpm lol it literally stops making power at 7k. Tuner says he's never seen a z stop making power before 7.8-8k

If he's the same tuner that tuned your car before. Then he's right.

Is it safe to have the car rev up to 8k??? N/A cars need some type of back pressure. I dont think going 3" would help much but I could be wrong.

Was this change in power due to any mod changes? Mine was building power all the way through to fuel cutoff. Then after installing the intake manifold, it doesn't, but i also did the pull with 91 instead of 93 and I have no Uprev tune yet (I have the software now!) I would look at the fuel you were using and weather changes.

Id assume the exhaust also. Believe it or not, there is such thing as too little back pressure. I see you have test pipes and that with the LTH and custom exhaust (depending on bends and how truly straight through it is), you've basically a forced induction exhaust setup on an NA car. I bet goin back to HFC's you would probably get that pull all the way through. Post pics of your dyno sheet if you have it.

Agreed, def needs to see a dyno. I have a similar setup except gears and tune. There are a lot of variables with just the information given

How are you seeing you are losing power?

Probably your manifold, if I recall, you didn't have that before when you originally got tuned. I remember reading some people lost power with those manis.

I was thinking the M370 too. When I removed the M370, I gained back +5 WHP peak and about +10 WHP at top end.

the motordyne manifold is known to add a good bit of power in the midrange and lose a little bit at the top end.

If you don't think more power in the midrange is worth sacrificing 5hp near redline, try removing the m370 and see if that fixes your problem

I'm not worried about power loss on too end. Mid range is more important. It's that my car is not makin anymore power past 7k rpm. I know it isnt the manifold. I gained good mid range with that. I think it was like 14whp and 10tq with it. I'll upload the dyno when I get home

Although you probably picked up mid range rower -- I think their manifold makes peak torque earlier, but at the cost of some top end.

I know about the manifold. That's not the issue because I would rather have more torque than 5 hp top end. Problem is the not making anymore power past 7k rpm. I just want some opinions on the idea that it could be the exhaust or muffler. Anyone know specs of the internal piping of the magnaflow muffler?

youre contradicting yourself......7k+ is top end...... mid range is 4.5kish. Not all cars pull all the way to redline. Its quite normal for a lot of cars to drop off before redline. Even hondas with their Vtec drop off before redline and 90% of factory turbo vehicles drop off before redline. Our cars, not so much but as everyone says, the manifold is why you're dropping off because thats the characteristics the manifold has. Now if you're making 5hp less then your baseline.....then you may want to start checkin things like spark plugs (which shouldnt be a problem if your under 75k miles) or in a bad case scenario, cylinder compression.

to put it simple, you're digging for an answer you want because you don't like the answer you're getting even with multiple people telling you what it is. Dont know where else to go from there.

post a dyno sheet

its not that im digging for a certain answer, its that i know it isnt the manifold because the manifold on the other dynos ive seen it drops 3-5whp in the last 200ish rpm..my car makes good power til 6900-7000.stops making power(plateaus) til 7800-7900 then dips down...the dip isnt the issue..im trying to figure out whats causing the plateau from 7-7800rpm..which in any z i havent seen that happen lol...i guess its better to understand when i put up the dyno sheet...let me email it to myself and upload it

update on OP...that baseline is very old when i had i/testpipe/exhaust...but even there u can see it doesn't stop making power

Can anyone tell by the graph?

Looking at the graph I can definitely tell the old one did not have that intake manifold. Looking at your exhaust mods, nothing there will prevent you from making power all the way to 8k. I'm still unsure how dramatic of an effect the intake manifold has on full bolt on cars like mine and yours (yet to dyno under exact conditions). I would definitely check to make sure your filters are clean. It looks eerily similar to how the stock intakes choke up after 6500 rpm and flat line. Don't count out the M370 though. I have one on mine and I'm showing power loss up top, but not sure how much if I were to switch to 93 on the rollers.

Could it be the upRev tune? Was the dyno tune the last thing you had done?

does anybody else have dynos with the m370 installed? Maybe I am wrong but I was under the.impression that the m370 would cause the car to lose a few hp up top compared to baseline... I did not think it would actully cause the car to plateau and stop making power alltogether. Like OP suggested maybe it's not the m370 but I am curious to see other dynos with the m370

This is my dyno between the M370 and stock manifold. This is untuned and the M370 is running 91, the stock is 93. Those are the only differences.

http://www.the370z.com/attachments/i...ynocomparo.jpg

Idk how much being untuned and 91 octane are skewing the comparison, but your loss in top end looks like a lot more than "a few hp" like motordyne claims

U have to tune for the Mani when your full bolt ons. I lost the exact same as u on the baseline. 12 hp. But gained it back after tune and around 10-12 midrange above baseline

That's why I'm reluctant to pass judgement on the M370 as of yet, especially with your issue as I don't know all the variables yet.

It's the manifold. It just makes peak torque lower in the rev range, which you can clearly see. A tune will only do so much.

Any other differences are as likely due to transient factors (e.g., intake temps) as not.

Also, see if you can get those results in SAE, DIN and STD tend to skew high on NA cars.

I'd be more upset there are 370Z's that made like 20whp more on that dyno with just i/e and tune :)

TAKE THAT JULIO! JK of course..

It's weird though, didn't look like you LOST power, but it does flatten out. How does the car feel? I mean, you rev until 8k, you're going to fall more into your powerband and it should move nicely.

There is definitely at max a 10whp difference in correction types.
I have my drf run files so I can so adjustments, but I've posted strictly DIN on other threads so I use it incase anyone cross references.

yeah I was about to say....those numbers look like they should be for a stock Z...how is he making so little power with all those mods?
But also going by the trend of the line before the plateau it looks like he would reach 300 if it did not level off like that. But still, 300 also seems low for those mods + tune.

Is that a low reading dyno?

It's a mustang dyno. Dynojets read 12% higher. So it'll be 313whp on a dynojet. But even on that dyno I/h/e cars are hitting 300. It also seems to me as if I would hit 300 if it would've kept climbing. So yea 20whp less and it's plateauing. FML lol

Checks sig ;)


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