Ok here is my question. Is there any advantage or HP gains anyone has seen in using the MFR housings over say Racing Beat or anyother engine builders custom PP housings? I just ask this because of the huge price difference I see.

 

MFR housings can't be completely duplicated.
Casting is quite different, sparkplugs are closer together, exhaust port opens later and has a smaller exit runner, waterjacket is relieved on sparkplug side to minimise housing warp........ to name a few.

 

Thanks has anyone ever dynoed difference housings to see if the HP differences?

 

Rob at pineaple told me that for the 12a's he has gotton about 160-185 out of his hommade ones on an engine dyno and he is really good and knows exactly what he is doing. he said the MFR housings are a bolt together 290-310, He basically said that the MFR housings always make about another 15 horses at least. And yes there are differences such as the casting, exhaust runners, etc. I dont think the port timing can be exactly duplicated either, cus the MFR exhaust might open a little later than the stock ones. if any one is interested i may have a set of 12a MFR housings for sale, they are used but in very good shape, no chippingi in the sides.

CJG

 

I might have a pair of 13b MFR housings for sale
they are used but like new and are the ones with the o ring groove in the alu.
what are they worth used? i know what they are worth new.
matt

 

you should be able to get around a $1000. thats half off.

 

Hmm I might be interested in those 13B housings. Post up a few pics of them.

 

yep $2,211.00 ea on the racingbeat site.

matt

 

when i have a chance i will take some pics i have very little time at the moment
to busy taking care of babies

matt

 

According to Paul Yaw's site, the MFR housings open the exhaust a whopping 2 degrees EARLIER than a stock GSL-SE/FC/FD exhaust port (MFR = exhaust opens 73deg BBDC, production - 71deg BBDC) 2 degrees at that point is maybe 1/2 to 1 millimeter. (I have a rotor housing that I marked off every ten degrees, it's neat to see how the distance the seal slides per degree changes around the housing's shape).

The 12A's, in 1st gens anyway, open up at 75deg BBDC, so in that case the MFR housing would indeed open its exhaust slightly later.

In any event, they're all whopping shitloads later than what Racing Beat does.

 

Speaking of p-port housings, does anyone have any information about RE-Amemiya's?

 

PICS!

 

My avatar is of a factory 12a peripheral port thats sitting on my work bench. CJ

 

I don't have a digital camera that works, even then I doubt it'd show up very well since I just used a Sharpie all around the circumference and then scratched lines and numbers into it.

 

Awright, so what's 5mm up and 5mm down worth in degrees?

 

Where at on the housing?

 

Oops, I meant on the exhaust. Late 13b, if thats the housing you have.

 

All the rotor housings have the same dimensions except for width (I know "the books" say they are different, but I don't see where when looking at them in real life)

I repeat my question though, where at on the housing? Near the top of the port or near the bottom?

 

If its a 13b rotor housing (with stock exhaust port), raise the roof of the exhaust port 5mm and drop the floor 5mm along the curve of the rotor housing face. (BIG D shaped port) What timing does that result in?

 

If any one is interested in a pair of MFR 12a housings let me know, they have about a 1/4 season on them with no chipping in the top or in the bottom. bolt together 290-310 RWHP. NA

CJG

 

Don't drop the bottom of the exhaust port as the earlier opening shortens the power stroke.

 

It also makes the engines louder.

But Racing Beat does it, so you, me, and Mazda must be wrong...

Only time I can justify opening the port earlier are for turbo engines that need quicker spoolup, and for nitrous engines that need all the exhaust port they can physically get.

 

My engine builder Pablo out of Pamdale California build custon PP housing using your own housing from turbo to 12A.
I'm getting 292hp at he wheel with a 58mm carb.
cost for the PP is $950 for the PP without the housing.
benoit@realride.com

 

One missconception is loosing "power" from an early opening exhaust port (of corse if you go to extremes [by having a really really big or extremely early open port] throw all this out the window). by the time the rotor has reached the early open exhaust port (lets say a exhaust port opening a streetable 80 degrees BBDC) there is very little moment arm the rotor exerts on the e-shaft (there will be less the 15% torque transfer from peak at this point) so what ever power there is left in the combustion chamer thats still expanding exserts little force in actually making more power at any thing from mid to high rpm. generally you will gain more power by exhausting or expelling the exhaust earlier and gain more power by having less pumping loss and a higher VE then keeping the gases in there longer. It takes an entire system as a whole to make all this work. If you have a tiny turbine or restrictive exhaust of corse this will not work, but who in the quest for power runs restrictive exhaust or small turbine?..LOL

summed up, the early exhaust open gain in hp from a better VE (volumetric effiency) and less pumping loss out weighs the power losses from keeping the still expanding gases in longer in the quest for more power from mid to high rpm verses low rpm torque. Another bonus as someone already stated is in a turbo car a quicker spool up.

~Mike..............

 

Would you think it is necessary to heat coat the MFR exhaust port for a turbo application? Different to the turbo housing the MFR housings don't have a steel exhaust sleeve being intended for NA use this might not be relevant. Using it for a turbo set-up anyonme knows of applications that run the higher exhaust temps just passed the aluminum without any coating?

Thanks
CW