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.