High RPM Flatline?

[Torinate]

I've been reading every FI thread I can find.

I read a few posts about centrifugal Superchargers and a flatline in HP about 6500 rpm or so. Boost went up but HP stayed the same or dropped slightly. I couldn’t find a definitive reason or answer notes but some people felt it was intake manifold related.

Does a new intake solve this? Does the 18 manifold “correct” this?

What’s the 18 manifold worth HP wise on a centrifugal 8-10 pounds boost application?

Still looking at my options for FI.

Wife got her new kitchen. My turn for Christmas!

Thanks!!

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[Notheryote]

Probably some to do with the TB, at least with a PD blower. With many PD blowers and the stock TB you hit a point in the higher rpm where you drop off, but getting a larger one will help carry gains into the higher rpm.

 

[Torinate]

This was with centrifugals.

 

[markmurfie]

Fuel octane related. Centri superchargers should continue to climb in HP with RPMs, as long as the fuel can prevent detonation with the extra increase in boost. You don't see the same trend on cars running E85, unless its tuned very poorly, or the intercooler just isn't enough to keep the IATs down. Just like turbos and PD SC's, centris can very quickly become nothing but hot air pumps at high boost levels.

 

[Torinate]

Ok. I hear what you’re saying. However, in the other threads, the IATs were consistent and there was no change in timing. Yes, a centrifugal should continue to build boost and HP, however in these threads the boost climbed but the HP flatlined or dropped from 6400 to 7200 rpm.

My questions is, has this been rectified? There was lots of banter about tuning and cats and intake etc. This was before the 18 manifold came out. Just curious if people are still seeing this with centris now or not.

Was it the intake manifold? Tuning?

Anyone have any light to share on this?

 

[Torinate]

https://www.mustang6g.com/forums/threads/chasing-the-procharger-flatline.82675/page-4#post-1935823

 

[3beeps]

It seems to be the intake manifold if you have a 15-17. Mine flatlined at 6500 rpm as well. I switched to the boss manifold and the car pulled very hard, but I don't have dyno results for proof.

Your best bet is to try a 2018 intake manifold. They're inexpensive and will be worth power regardless of whether or not it solves your issue.

This video here shows the flatline on the graph (at the end).

 

[Torinate]

Haven’t got an issue yet lol.

Still waiting to pull the trigger on a forced induction set up.

So many great options out there. Probably can’t go wrong with any of them. But this was something I read and wanted a “fix” if I go centrifugal.

 

[SolarFlare]

Manifold related. Change to an 18, Shelby or boss and you’re good.

 

[Torinate]

Nice!

Thanks!

 

[80FoxCoupe]

I've been reading every FI thread I can find.

I read a few posts about centrifugal Superchargers and a flatline in HP about 6500 rpm or so. Boost went up but HP stayed the same or dropped slightly. I couldn’t find a definitive reason or answer notes but some people felt it was intake manifold related.

Does a new intake solve this? Does the 18 manifold “correct” this?

What’s the 18 manifold worth HP wise on a centrifugal 8-10 pounds boost application?

Still looking at my options for FI.

Wife got her new kitchen. My turn for Christmas!

Thanks!!

I picked up 90whp peak swapping to 2018 intake.

 

[whatsup62]

https://www.mustang6g.com/forums/threads/chasing-the-procharger-flatline.82675/page-4#post-1935823

yep that was my post...way back when. Actually completely forgot about it. There were a few reputable commentators on here that really thought this was tune related and sunk a lot of time into it. The weird thing was some had issues with this and others didn't. The one theory that made since to me was that at a certain level of boost/rpm/IMRC signal - things would work against each other and basically get stuck. There were some intakes that had a different route (vacuum lines) or components in the IMRCs that didn't seem to have this issue, late 16s into 17s and then you just didn't hear about it anymore. In my case I had the flatline at 6750 and revved to 7500. Boost would increase but power flatlined. I went away from the stock 2015 intake and got the Edelbrock Victor II. Went back to the dyno and she pulled all the way to redline...problem gone. This was with a Procharger P1SC.

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