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

I'll definitely take you up on that when I'm good and ready ;)
Thanks

This is part of the reason why I love mt.net, the fact that we will share parts just get testing done is great.

If we really want to go crazy depending on when 18PSI does his testing, I might be willing to offer up my BEGI cast manifold for use. Only issues I know off the top of my head would be a different TPS and idle valves.

I think you'll be fine with the VICS with a stockish redline. You can remember from my dyno more or less where the torque and hp start to tank, though my boost did taper down a tiny bit after peak power (because remember, I was making 10psi on a 7psi and not boost controller). It now ramps the boost up from 10psi @ 6500rpm to 12psi @ 7500 and the torque curve feels a lot flatter when you drive it. Assuming that taper actually held the torque flat thats about 300hp. I kind of feel like, yes the runners are kind of small and make a good deal of drag when you try to cram a lot of air in, but if you have the head room in the pressure department to support higher pressure you can more or less over come it. But I think the VICS will move your theoretical pressure vs flow plot vertical on the compressor map compared to the same engine with a flat top when trying to make the same amount of power.

Am i learning in this thread that the VCTS manifold sucks and i should gut the system?

No such thing as VCTS.

VICS = Variable Inertia Charging System = alters plenum volume and Helmholz frequency to improve midrange torque. Keep this, it's good.

VTCS = Variable Tumble Control System = improves intake charge tumble at low RPM/low CLTs to improve cold-start emissions. This is pure smog garbage, remove it at once.

Yeah, typo, my apologies.

I knew VICS was good. Had it on my Escort.

Never bothered to worry about VTCS, but I guess I may as well gut it this Spring before I get tuned for corm. What gains should I see removing it?

Lars,
I plan to do a test day soon, in about a month is my guess? I plan to test several intake manifolds on the same day. I would love to test your manifold as well, maybe you can come up? I will leave the car on the dyno and change manifolds before testing again in hopes of usable data. Maybe you will extend your offer to me as well?

oh snap that would be awesome

you think they'll appreciate coolant all over their dyno?

How does changing the IM release coolant? Well unless you're a pussy and still have the TB heat still hooked up.

I is such a pussy but see no reason it means I have to get coolant everywhere. I will have all my manifolds set to take the OEM TB and will use the 64mm Skunks TB so I will use the same TB for all the tests......at least that is my current plan.

The skunk doesnt have provisions for TB heat so you're all set.

oh is there no coolant port between the runners on the BPZ3?

Not that I recall, I think thats a 1.6 thing. :giggle:

1.6L is bossmode.

What about the fuel line routing? Doesn't that go between the runners?

I dont know how the stock NB routing goes, my M-Tuned routing both lines cum in from the rear.

The BP6D Chris will be running doesn't have any stupid coolant ports in the IM. And if he's smart he will already have looped the stupid TB coolant lines (or will do that prior to dyno time). Nothing else will prevent him from being able to carefully remove just the IM and nothing else and replace it. Been there done that.

Shoot me a pm with info. Depending on when it is I might be interested in heading up to NC to help.

I know with my square top I had to hog it out to match the Skunk TB. The size difference is pretty noticeable.
https://www.miataturbo.net/attachmen...ine=1382465456


I have one square top gasket matched to the Skunk TB/ports and one that is left alone. If you want a hand, or another manifold(s) to play with hit me up. Depending on schedules I might make the trip over your way. Wife will probably send me with food as well. Can't do dyno on empty stomachs.

I haz makes gooder pictures here: https://www.miataturbo.net/engine-pe...me-size-72232/ :party:

FM turbo testing, intake manifold shootout! - MX-5 Miata Forum

VICS vs flatop with GT2560:
http://forum.miata.net/vb/attachment...1&d=1333151217

Wow so impressive to see so little difference between VICS and Flat top (price lowering sound)

I still have a hard time accepting FM's dyno results, especially when they show a GT2560 performs better than an EFR.

I thought the whole point of the flat top was for big power... 178hp, I wouldn't think there would be a big difference anyways.

They make more power even on NA applications.

Don't think I'm being a dick because of other threads, but I get that they make more power on NA. My point is that it's not really a huge amount (probably not worth what they are selling for, and the difficulty getting them). But for higher power applications the power increase would be more dramatic, making it worthwhile. So a comparison at low power levels doesn't seem that helpful, and a bit misleading on the point of a square top.

I admit I could be way off here.

From what I gather for "big power" people go to the Honda manifolds.

So get VICS and spend the money on Supermiata/Skunk 2 TB, you'll get some dough for cat food......