Anyone with FI add a square top IM?
 

I'm curious if you get the same gains with the square top on cars with FI

Thanks!

Yes.

no never.

Read the last few pages of Soviet's build thread.

Andrew, can't seem to find it

Also look for the FM dyno test on m.net. However they didn't rev it above 7200. Most of the gains are >6000 RPM.

basically you lose a couple wtq at various points in the lowend/midrange and pick up a BIG chunk of power and torque past 6500

how does this belong in the race prep section?

He is obviously Richard Allistor or Dougie Sweetmaster

FM did a forced induction squaretop test?

I don't think soviets thread really gives us any info specifically on the squaretop either - too many other changed variables.

You're right, it probably doesn't. I just do HPDEs. There are so many knowledgable people in here that I figured I'd get some solid answers. I just bought one, in the for sale section, a minute ago.

Thanks to all

I used one in the build I just finished but there were no before numbers, actually we're still waiting to get to the dyno for numbers at all. But what 18psi stated above about power seems to be the common result.

Probably hasn't been tried much because 0.5 psi more will do the same trick...

For the most part yes, but once you approach the flow limit up top, .5psi more actually won't do the same trick, and/or this would be like uncorking "free" horsepower that is otherwise choked up

It's not free, it's $500 ;)

Related: Has anyone actually put a number on this "flow limit up top" for the stock manifold? At what point does it choke under boost?

The way I read it quite some time ago, boost is actually a measurement of resistance to flow in the system. All other things being equal, 5psi on a BP4W with restrictive stock exhaust, log manifold & GT2560R is going to make vastly different power compared to 5psi on that same BP4W with a +1 valve ported head, tubular manifold, 3" exhaust... you get the idea.

Anything you can do to reduce resistance in the system will show benefits. With the squaretop vs stock, the question becomes "where do I see these benefits?" Is this is a street car that lives most of its time around 4k with occasional trips to redline, or does it spend most of its life around 6k for 20-30 minutes at a time BECAUSERACECAR?

The $400~500 pricetag of the squaretop might be worth it to the racecar guys but that same $400 buys you a lot of goodies on a street/hpde/autox build.

haha ok valid point
Exactly. I think most the street/daily driver VICS guys don't really even need this thing. Heck, even the VTCS guys don't really need one for the street (and one of the reasons I'm going to try using my vtcs mani at 1st and only switch to the squaretop if I'm unhappy with it). The track guys love this cause its OEM, bolts right up, and actually holds together unlike some of the honda mani's we've seen. And those running setups that make serious top end power obviously want it too because the stocker chokes up pretty dramatically (at least the vtcs does) past 300 or so.

V: My offer still stands to loan you my spare VICS manifold when you get around to testing the VTCS vs Squaretop. I'd be nice to see all 3 on the same testbed with some 100kpa+ data