VTCS mani was de-butterflied.
VICS mani switchover was 5400 RPM
Tested on 2.0L n/a stroker motor by FM.

 

For a track car with a >= 7400 RPM redline, the Flat-top is the clear winner.

For anything else, pick your poison.

 

(Sent from phone via capitalism)

Now add boost and do it again. Kthnxbye

 

IM resonance effects are not affected by absolute pressure. So with boost, should be about the same.

Affected more with temperature. Higher temperatures and pulses and sound move slower. So with high IATs, maybe the resonance effects are moved to a lower RPM.

 

vics was operational? 5200?

 

Yes operational, at 5400 RPM. I find 5600 RPM the "correct" point when RPMs are slowly rising. If RPMs are rising rapidly a lower switch point is better.

 

180whp with a stroker for 10k? Isn't emilio making 170whp with the non North American motors, slight head work, rb header, and tune. I could replicate Emilio's motors for 3k or so...

 

Wait, with boost would gains follow the same percentage gain? Or would you just get a lousy ten hp.

 

% gain.

 

Up to a certain flow point.

 

Has the book been shut on the gutted vs. functional VICS under boost?

 

No

 

I understand this, but I still want to see it

 

OK, so if I have a VICS manifold on a turbo track only car (~15psi), do I get more area under the curve with the VICS intact or gutted?

 

Define 'gutted'. Do you want to just remove the butterflies, or also machine it out into one big plenum?

--Ian

 

machine it out into one big plenum seems like it would make more sense...I've seen a post where it looks like ZX-tex did this, but no before/after dynos or anything.

 

Gutted in this context means reaming out the entire Helmholtz chamber and everything else into a giant plenium. Just removing VICS butterflys would make the manifold worse IMO. VTCS is another story - removing those butterflys is a no brainer.

 

Any idea what causes that dip at 3500rpm?

Jim

 

FM's tried this a couple times (including yesterday, according to the thread on miata.net) with a VICS manifold and seen no improvement. That was in an NA engine, not a turbo one, but it shouldn't matter.

--Ian

 

WTT: One VICS and one VTCS for one squaretop...