I have searched and I found that the RE UIM will not fit on the s4 LIM but my question is, will the whole 13b-re manifold fit on an S4?

 

It will not fit.

 

Oh well, thanks

 

WRONG. it will fit an s4. provided you have a 13b-re

 

^^ thanks a million...

hey what did you decide to do about your forced induction situation?

 

i have a rew manifold on my S4 lim

 

thats actually the route I decided to go but I have been hearing you need and S5 LIM.

What did you have to do to get it to work with the s4?

 

adator plate and enlongated the mounting holes on the fd manifold

 

where did you get the adapter plate? and what was it used for? I am assuming it was just used for the transition between runner sizes and the holes were for alignment.

Also how thick is your adapter plate?

 

plate is 3/4" thick and is placed in between the manifolds. yes its used so the manifold runners line up, I also gasket matched the manifolds and ported the adaptor for a nice smooth transition and increased flow

 

do you think 1/2 in would work? I have some of that kicking around.

 

Hell no, the RE primary runners are the same size as REW secondaries.



s4 TII secondary runner.


RE secondary runner.

 

so the one on the right is the rew?

and REW>RE?

 

The one on the right is a RE, on the left is a S4 TII. RE is bigger than all REW, S4 TII and S5 TII.

 

got ya, thanks

 

ya, RE runner/ports are HUGE. im goin with a turbo set up. trying to decide now if a BNR stage 4 is worth the price over stage 3...but that s a whole nother ball game

 

The stock ports are tiny.

 

hell yes

 

Not to mention I opened up the RE UIM about .125" in some spots to port match it to the RE LIM. When I was done the ports were so big that I had to trim the factory gasket. I didn't open up the LIM ports at all, just smoothed them out a touch.

RE > ALL

 

& if you've got a 3/4" adapter why the **** wouldn't you countersink some bolts, or use studs in there so you wouldn't have to oval out the mounting. One of the two LIM, S4/5, is off enough on the mounting that it can be done. I've seen it.

BTW - make sure you get dyno plots before and after the REW UIM swap just to make sure you didn't loose any power. Mani's are matched for a reason ya know

 

yeah, I may see if I can find some tapered head bolts or studs to mount the FD UIM to the S4 LIM. I'm going to try to make it work with a piece of 1/2 inch aluminum. I'm probably going to have it tuned with all the s4 stuff in the spring, but I'll try to dyno it with the FD stuff right after. I'm really not familiar with the process of having a car dyno tuned but I hope I have the time to try both manifolds.

 

I'm not talking about dyno tuning, I'm talking about mis-matching mani's and having it be detrimental to performance. The manifolds are matched for a reason. We know that the REW has balance problems between the front and rear rotors. Under vac one runs lean, but under boost the same one runs rich. The problem is multiplied exponentially as boost/exhaust flow increases. So, by putting the REW UIM on an S4/5 LIM you may be putting that problem on a motor that never had it. In my opinion though the problem lies in the LIM but that's an opinion and there's no fact behind it. Extrude Hone has seen flow differences upto 20% between the front and rear rotors on the REW manis. However, without dual EGT gauges and making a dyno run on the stock mani's, then switching over to the REW UIM on the same day and making a few more pulls and then overlapping the logs for Lambda, EGTS, & power, you won't know anything other than, "Yeah, it's more asteciacally pleasing to have an REW UIM"

 

I understand that the manifold s were matched for a reason. I also understand that I want to mismatch them for a reason, hopefully more torque due to the longer runners (longer than stock S4).

You say there is a 20% flow difference between front and rear rotors. Hopefully I'll find someone with a flow bench and figure out where that is coming from. Maybe Mazda built the engine like that for a reason, I can't imagine why, but who knows, or maybe someone just F'd up and they rolled with it because it wouldn't, be a problem at stock output power levels.


Its all just bench top racing now but I will test, both manifolds to the best of my capability.

In the end the FD and S4 UIM and throttle body are on par on a performance level, you know what, the FD manifold does look much better at the end of the day.

 

True, but mismatching them could potentially throw off the dynamic effects of the intakes that Mazda spent probably millions of dollars researching.



That's what everyone is assuming


I don't know of any real way to trully test the manifolds the way the factory did when they opimized them. But that's why they're the engineers and I'm a finance guy. The only thing that I can think of is a few dyno pulls to see the after effects.

 

The FD LIM is "offset" towards one rotor (towards the front?), which is quite suspect when it comes to the flow imbalance.