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13B PP road racers....decisions

Old 07-20-08, 08:35 PM
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13B PP road racers....decisions

Im rewiring the FC this year, complete rewire. However Im also starting up school again thanks to my long years of military deployments. So during this time, my engine will just be sitting, for atleast a year or more. Ive wanted to build a crazy 20b PP motor for quite sometime, but due to the extensive bank account you must have this is not possible. So Im my thoughts are a 13b PP. Which means I will be selling all turbo parts on my car (turbo, manifold, dp, gate, etc) Im going to school to be a machinist, so it may be possible for a class project to make my own housings. I would like some input from all of you. I did love the feel of a high HP turbo, but I feel i could be much more reliable with a NA. The car is for track use, and maybe a nice annoying street drive here or there. Let me know what you guys think, the average cost of a well built 13b PP, and the HP i would expect from a EFI 50mm ITB 13b.
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Old 07-21-08, 05:08 AM
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I think companies like TWM only make 55mm and 62mm ITB's now...the 50's were way to small....especially for a P-Port. The 13B PP I'm currently building will run a 62mm Terminator IDA-style carb.....I can even run this carb on a Streetport! Rotaries love as much air as they can get, as long as it is tuned properly and using correct venturies.
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Old 07-21-08, 08:13 PM
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Thanks for the input. Ive checked out TWM and some other sites. As far as building housings. Whats the average price to have someone do them? And during this process, should the rotating assembly be balanced since higher rpms are reached?
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Old 07-21-08, 11:01 PM
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If you are going to school to be a machinist and you dont plan on having the car running for another year or so, why pay another machinist to do the job? As far as the housings go, just about any machine shop would have the equipment to do the job. For a lot of diy information about building PP housings, heres a link to Paul Lamar's site.
http://www.rotaryeng.net/intake.html
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Old 07-22-08, 01:41 AM
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...although its a turbo PPort, this shows some good pics of what needs to be done to make the housings.....if you can, wait and do the machining yourself....a good P-Port job including new housings can run you near $2000.
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Old 07-22-08, 11:53 AM
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Originally Posted by Turbo23 View Post
Thanks for the input. Ive checked out TWM and some other sites. As far as building housings. Whats the average price to have someone do them? And during this process, should the rotating assembly be balanced since higher rpms are reached?
i had mine balanced, in my case it was better than trusting some expensive and mismatched parts (who knows where my counterweights are from). its also relatively inexpensive.
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Old 07-22-08, 02:53 PM
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I built my current 13B PP about 4 years ago. I bought new street housings from Mazda Motorsports, and had them P Ported by Nick at Rotary Reliability & Racing in Santa Anna, CA. Back then, he charged $500 labor per housing to port them. This engine makes strong power, a little over 300 rwhp with a 51 IDA Weber.

It is too obnoxious to drive on the street. Being stopped at a red light, waiting for it to turn green, is awful in a PP motor. Stop and go driving really sucks.

They are made for running all out on a racetrack, and that is the only thing they do well. Fuel milegae is poor, about 4 minutes per gallon.

Total engine parts cost about $6000, and I did the assembly. I have been road racing PP motors since 1997.
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Old 07-22-08, 03:10 PM
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Thanks guys for all the knowledge. What are most of you running for headers? a simple racing beat race header or something custom? Also do many of you have different gears? I was told stock t2 gearing is pretty bad for PP motors.
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Old 07-24-08, 11:17 PM
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I've been looking into headers too...probably gunna be a custom job. You want the primaries out of the block to run more like the SDJ setup with a little straighter pipe before the bend. 2" or 2.25" primaries depending on the size of your porting...the merge should go to 3" at least.

...some say collect at the rear, some say collect early....its still up in the air for me. Since this will be a street-able P-Port (sure) I want to collect at the end of the trans to have room for some muffs pre-diff.

Upgrade your ring and pinion to 4.44 or higher to help with gearing....drag P-Ports run 5.00's and such to make up for the torque band.
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Old 07-25-08, 12:03 AM
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Originally Posted by Turbo23 View Post
Thanks guys for all the knowledge. What are most of you running for headers? a simple racing beat race header or something custom? Also do many of you have different gears? I was told stock t2 gearing is pretty bad for PP motors.
i think RB headers will work, but they arent optimal. so like put em on, get everything else dialed in and then redo the exhaust, maybe

gearing is not so hot, 1-2 is a big drop, 3rd isnt much better. http://www.youtube.com/watch?v=i2fjsnWgHmk&feature=user
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Old 07-25-08, 01:33 AM
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...you will also need to check your local track sound restrictions....that would be a good way to start before building the exhaust.
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Old 07-29-08, 12:15 PM
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Street transmission gear ratios are worthless for a PP motor. With street transmission ratios, every time you shift gears, the PP motor falls out of the power band, because the ratios are too wide. Outside of the power band, the PP torque falls off noticeably, so it feels like it takes forever before it climbs back into the power band. You need a racing close ratio transmission to run a PP motor properly. Most racing close ratios have a first gear around 2:1, which is about like second gear in a street tranny. This is another reason that driving a properly setup PP on the street is difficult. With the race tranny and the race engine and a light weight flywheel and light weight racing clutch, your road racing 1st gear will pull out to 60 mph, BUT the engine won't pull smoothly till about 30 mph in 1st gear. You will have to slip the clutch up to 15 or 20 mph just to get a decent launch. Again, I have been doing this since 1997, I know what I am talking about, the PP is pretty obnoxious to try and drive on the street.

With a well tuned PP and a close ratio transmission and a low rear end ratio, the naturally aspirated PP is a rocket on a road race course.
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Old 07-29-08, 04:14 PM
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the car will be a track car, only street use will be to run it alittle. No small runs around town or anything, just up and down the road.
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