FMIC options on hotside cars
 

It's pretty much accepted that you don't want to run a fmic with a roots blower (unless it's a short track setup like trackdog's) because the tb is at the back of the blower and the extra intake volume hurts throttle response. In the six years I've been reading miata forums I've never seen a supercharged car running a fmic turbo style, so I'm wondering if anyone can vouch for the the 'theory'. Anybody out there run a standard fmic with a hotside roots blower, and did it really hurt throttle response? If so, is it bad enough that a light flywheel wouldn't make up the difference?

look harder, i have seen several

They're out there. TDR offers one.

They shoulda put a centrifugal blower on the miata and called it a day. Would have been much simpler to intercool.

look in the for sale section also. You will see droptopdrifters i/c set up for his M45 charged car

Nick,

Yes, it is completely possible. Actually, i'm running that exact setup that you are talking about. I have run it both with the TB before the s/c (per standard JRSC instructions) and have run it in the stock location ("turbo" style). Did i notice a difference? Yes. But there are several configurations here.

JRSC - with stock cross over pipe. Very fast response....on stock boost. On my 99, runnign anything more then the stock pulleys caused detonation. The only way to combat this was to pull timing. I hate pulling timing.

JRSC with FMIC and TB in front of s/c. There is a hint of "lag". But nothing like you'd think. It's about a 1/2 to 3/4 second delay between your foot going down and seeing full bost. But overall, worth the delay. Top end of the revs pulls much smoother/harder then a un-intercooled setup. You can go with the highest boost pulleys with no timing control. (I did, here in hot ass Ga.... and did a couple drift events with no problems).

JRSC with relocated (stock) position of the TB. Very fast response.... maybe even a bit faster then just the crossover pipe. There are downsides. You must add in a BOV and get creative with vacuum routing. You have to use a dual input BOV (one with 2 signal ports... vacuum signal and boost signal, the Greddy Type-S is one of these). To run it right, you have to get vacuum signal for the BOV like you would on a turbo car, but then you have to "t" it off and run one line to the bypass actuator. Also, if you're running a mild fuel management setup, you have to deal with "Zero boost". This is where there is a loss of vacuum on the bypass and it starts closing. This causes boost to start building and pushing on the TB...which makes for INSTANT response. BUT, if you don't go into boost , the BOV starts venting. If you don't have good fuel control, it'll run the car rich and bog slightly because the MAS is seeing incoming air thats getting vented off. I jsut actually moved my MAS to blow-though to see how well that works. If you have any engine management that runs off a MAP sensor, then there is no problem.

I know about the TDR setup and I've seen some pretty clean diy copies of that arrangement, what I'm talking about is a fmic that snakes the pipes down and around the core a la Flyin Miata or Begi.

Badger, thanks for the insight. I've followed most of the major posts that talk about running the TB in the stock location on a blower, but they are almost all done to M45's and I'm running an M62 so I'm not so sure how much of that info really applies to my set up. I've tossed around the idea of using a tb in the stock location and a traditionally routed fmic with two bov's hoping that would handle the extra volume the M62 can throw down, but I'm not quite convinced I'd like it. That 'zero boost' condition is making me hesitate. I'd really love to drive a supercharged miata that's running a tb in the stock location before I do it to my own car - anyone in the Bay Area want to give me a ride?

Anyway, if running a traditional fmic with the blower throttled would reduce throttle response, I'm wondering if throwing a light weight flywheel would counteract it and get me back close to my current throttle response.

You obviously haven't been paying attention. :D And although I did it with a Hotside Autorotor several times, it's the same as using a roots. Throttle response is dependent on location.

Mark

Aside from throttle response, if you have any idle droop issues, mounting a light flywheel will make it worse.

Man, its an extra hassle but do the FMIC and TB relocation. Just do it. lol.

Nick,
I think that running dual BOV's would work just fine. Your fear of the zero boost isn't much to be worried about. I mounted the air flow meter to a 'blow-through' style post intercooler.... so far it seems to have taken care of ALL driveability issues. Will be doing a bit more driving with it tomorrow before she gets sold and will let you know.

But for a M62, do you know what size the bypass port is compared to the M45? Either way, the bypass on the M45's seem to be just fine... i mean, there is that one moment when shifting that the BOV was utilized, but driving normal it works. I say give the 1 large/2 small bov's a go!

I have this set-up and throttle response is very quick with no lag at all. It also got rid of any Idle droop symptoms too. I had the BOV flange welded on the outlet manifold and a vacuum line tapped downstream. Heres is my set-up

Attachment 214769

I too second the "running two BOV's on a MP62" due to it produces more AIR than a M45. It would vent a lot better.

Badger - could you post a pic or two of how you've set up the maf? I've toyed with the idea of a blow through maf too but everybody said "BRP tried and it didn't work well'.

Mr. Mazda - Is the hose running along the top of your radiator for your iac valve? Why not run it right into the charge tube? I like your setup, what type of BOV's would you recommend using?

here ya go!

Attachment 214764
Attachment 214765

The "clear" looking hose loops around and goes to the nipple on the s/c outlet.

The one I used is made by Number 1 one, kind of a greddy RS knock off.
http://www.nopionline.com/nopistore/...20%20%20Turbos

Acutal Greddy RS
http://i98.photobucket.com/albums/l2...rsports/10.jpg

Hey Badger, did you use to be droptop? Looks like me and you have the same people doing to the same stuff to our cars over at CCR.

Thanks guys. Badger, is that your maf on the passenger side of the engine bay?
BTW - why are you selling the car? are you unhappy with the setup?

One more question: Badger, where do you run the IAC valve hose?