Well i am building an n/a peripheral port 12a with the Mazda factory racing housings. I have been looking at the timing of the housings in comparison to others and i am thinking of having the intake ports openings a few degrees earlier, widening up the exhaust port a little and having it close a little bit later also. I am going for peak power because the rx3 it is going into is going to be used primarily for drag racing. I have lightened rotors, e-shaft, flywheel, mfr rotor bearings, hardened gears an 3 window bearings, i have collected basicaly everything need but a few oil pump/movement things.

Thanks, Mike

 

[quote name='mike_rudy' date='Aug 1 2005, 08:42 PM']Well i am building an n/a peripheral port 12a with the Mazda factory racing housings. I have been looking at the timing of the housings in comparison to others and i am thinking of having the intake ports openings a few degrees earlier, widening up the exhaust port a little and having it close a little bit later also. I am going for peak power because the rx3 it is going into is going to be used primarily for drag racing. I have lightened rotors, e-shaft, flywheel, mfr rotor bearings, hardened gears an 3 window bearings, i have collected basicaly everything need but a few oil pump/movement things.

Thanks, Mike


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The stock housings should be good for 310 HP or around that at between 10,000 and 10,500 RPM.



The engine is the easy part. I would be working on the driveline and suspension.



The trans is the weak link. If clutchless shifting is the goal, then a shock absorbing system for the drive shaft is needed, or an adjustable clutch that can slip a bit with each shift, to keep from shearing drive line parts.



Take a season to get the setup working and into repeatable times, with good reliability. Then swap out the engine and build the big one. The exhaust ports can use some help, but a Pport needs ver little help timing wise on the intake. Bigger runners yes. Same length exhaust primaries to the collector for sure.



This RPM range is (in my opinion) outside the range of the stock oil pump. An external aftermarket pump with 110 PSI, would be my choice. The wet sump is still OK. Pickup at the rear of th sump.



A scattershield around that flywheel and rev limiters on both leading and trailing

are required.





Lynn E. Hanover

 

Oh i have all that good stuff i am using a t-5 with liberty pro-shift gears, 8.8 rear end moser axles c clip eliminators, posi, i have a set of 6.14 gears and 5.67's, i am also right now in the middle of putting in a 4 link back half which should make for good 60' times, and not so bad autocross hill climb handling, i am running dual accel 300+ ignitions with the accel drag coils, surface gap plugs(can't remember the number but they are the colder ones) i have one of the old 12a oil pumps that is larger, i was wondering if i could use an oil pump from a TII in a 12a? I am also going to be running an electric water pump.



Lynn, how long of primaries did you use in your race PP 12a?



Thanks, Mike

 

here are a couple pics of the housing i don't think they have been modified. The exhuast runner looks fairly small but it is like straight back and looks like it will flow a ton, the exhuast port i think could be just a little taller and a bit more evenly wide, other then that i think i will just clen up the ports a bit

 

I personally would leave the ports alone and concentrate on other areas of the engine. The ports are definitely not small. If you make them larger, you will change their timing. One thing I've found about Mazda and their racing motors is that they do their homework on port timing. I don't think your going to get any better results by changing their setup.

 

[quote name='mike_rudy' date='Aug 4 2005, 09:19 AM']Oh i have all that good stuff i am using a t-5 with liberty pro-shift gears, 8.8 rear end moser axles c clip eliminators, posi, i have a set of 6.14 gears and 5.67's, i am also right now in the middle of putting in a 4 link back half which should make for good 60' times, and not so bad autocross hill climb handling, i am running dual accel 300+ ignitions with the accel drag coils, surface gap plugs(can't remember the number but they are the colder ones) i have one of the old 12a oil pumps that is larger, i was wondering if i could use an oil pump from a TII in a 12a? I am also going to be running an electric water pump.



Lynn, how long of primaries did you use in your race PP 12a?



Thanks, Mike


[/quote]





It is the stock factory intake with one 3/8" spacer under the carb. I never measured it. Its still at the old house, but I can get to it, or look closer when I bring it here.



What is a T5 and what is the "Pro-shift" feature of it? I need a good trans for road racing. I took every other spline off of the Richmond Gear 5 speed. It is much faster on the shifts, but not as fast as the Saenz, which breaks every time we use it.



Lynn E. Hanover

 

a borg warner t5 came in many mustanges and camaros, the pro-shift feature is sumthing liberty transmissions does,, they take off the syncros and put on these big mother gears, not what you are looking for though

 

Lynn, would you happen to know how long your exhuast was before it was collect on your PP 12a?



Thanks, Mike

 

T5 is a junk 5 speed box that Borg-Warner made, originally for low torque four cylinder applications, but eventually found its way behind V8s of no more than 300lb-ft. It is fairly weak. The 300lb-ft rating was a joke, and breakage is quite common, if you could even find a V8 T5 in workable condition. The four cylinder and V6 versions had very wide ratios (starting with a 4:1 First), whereas the V8 version had only marginally wide ratios (starting with a 3:1 First).



"Pro-shifting" is essentially removing the synchronizer cones and milling off every other synchro spline. Used to be called "slick-shifting" back in the day. Liberty prefers to machine the whole splined area down to form a "hub" on which to press one of their special hardened collars for reduced wear, but it still looks like every other spline milled away from a standard gear.



I would imagine that slower shifts would be a fair trade for not breaking every time it's used.

 

Heretic, How do you figure the T5 pro-shifted will shift slower? I have a freind with a proshift T5 in his mustange and just that conversion took of almost 3 tenths of his quarter mile time. Down shifting is much slower because do have do double clutch do to the fact there is no syncro. Up shifting you can just about shift without the clutch, my freind only shifted the 2-3 gear shift with the clutch because when he slammed it it spun the tires.

Although you are right most of the T5's arn't that great on transmissions, do to the fact they can some odd composite syncros that broke and were crap if power shifted, the world class ones that were in mustange gt's arn't exactly horrible.



Mike