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Opinions of race clearancing rotors??

Old 12-14-06, 07:10 PM
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Opinions of race clearancing rotors??

Yo folks,
I am building a new engine for my ITS car, i shift at a conservative 8,000 rpm and and wondering what you feel is the need for me to have the rotors clearenced. here is a link to the racing beat website that describes the process if you are unframiliar.

http://www.racingbeat.com/FRmazda2.htm

Is this needed and worth it???? Thanks ladies and gents, I appericiate the help!
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Old 12-15-06, 12:38 AM
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Their use of frames makes that link not point to anything correct (unless I just missed it) but I run max clearance on all my 12A race engines. According to a Mazda race manual of some sort, of which a .pdf has floated around the forum before, the hot trick is a "conical" clearance for lack of a better term.
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Old 12-15-06, 12:53 AM
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I doubt that it's legal, or needed.
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Old 12-15-06, 09:27 AM
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i dont think its a legallity issue. All that the process is is removing material from the side of the rotor to prevent it from slapping into the iron at high rpm...I only **** at 8 though. So I am leaning twords it being not needed.
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Old 12-27-06, 12:47 AM
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Smile Don't Worry

Hi There,

I just put my fresh engine in my race car last week. 13b street port, stock 1990 rotors, stock bearings. Clearances I ran last year.0025 on the rotors and mains. Ran for 40 hours at 9000 RPM pulls in 2nd and 8700Rpm in 3rd and 4th gears. Oil temp coming out of the engine before cooling it down was 250 to 265 Deg. Oil pressure was 120 PSI (Stock Turbo oil pump). I measured my clearances after last season no **** .0025 on both. The shaft had some visual marking but nothing that could be measured. About 15 minutes on the lathe with 2000 grid wet sand and they cleaned up no problems. One thing that did stand out was the stock apex seal (2mm thick) wear. Total lost on them on hight was (All the same) .0200 after 40hrs. It seam I will be replacing the stock apex seals every two years.

I run a Mega Squirt fuel, ignition program and pull at the rear wheels in 4th gear with 4:11 Gears, 225/50 R15 Ra 1 Toyo tires 180HP at 8400 RPM and 110LB @ 7500RPM.

Best part about my rebuild after one full season of racing, One O-Ring set, two seals, one set of apex spring long and short, one timing cover gasket. Resurfaced end and center sections (New at the start wear about .0030 to .0050). Total cost $700.00USD. for rebuild my time about 20 hours. Cheap!

Race Hard and Safe.
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Old 12-27-06, 05:37 AM
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Question

^ what intake manifold you running? Thats some high revs for a NA street port (both peak power and tq)
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Old 12-28-06, 02:26 AM
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the modern (86+ 13b) rotors are clearanced fairly well from the factory.
theres a 50/50 chance that you may not need to even touch the rotor.

stock assembly is good for a constant 8500rpm assbeating, if not more


I would suggest having your rotating assembly balanced though, as this can be improved upon quite a bit from the factory. Rotaries don't have a whole lot of rotating parts so the factory can get away with some sloppy balancing and still have everything happy.

Happy Rotoring,
Ben Martin
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Old 12-28-06, 08:10 AM
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"I just put my fresh engine in my race car last week. 13b street port, stock 1990 rotors, stock bearings. Clearances I ran last year.0025 on the rotors and mains. Ran for 40 hours at 9000 RPM pulls in 2nd and 8700Rpm in 3rd and 4th gears. Oil temp coming out of the engine before cooling it down was 250 to 265 Deg. Oil pressure was 120 PSI (Stock Turbo oil pump). I measured my clearances after last season no **** .0025 on both. The shaft had some visual marking but nothing that could be measured. About 15 minutes on the lathe with 2000 grid wet sand and they cleaned up no problems. One thing that did stand out was the stock apex seal (2mm thick) wear. Total lost on them on hight was (All the same) .0200 after 40hrs. It seam I will be replacing the stock apex seals every two years.

I run a Mega Squirt fuel, ignition program and pull at the rear wheels in 4th gear with 4:11 Gears, 225/50 R15 Ra 1 Toyo tires 180HP at 8400 RPM and 110LB @ 7500RPM."

Heavens to Betsy SCCA RX7 Racer, your setup is very familiar to me including shift points, tire sizes and everything. Differences to my set up asre that I was running a Holley 4 barrel/ Racing Beat manifold intake and a cobbled together stock S4 ecu set up. Got you a bit on power though. I got 185 rwhp at 8500 and 134 ft lbs at 6500 rpm. The carb/ ignition set up was not optimized at all, just something I could put on the motor and finish out the season with a new motor.

Going to convert to my Megasquirt/ ITB setup this winter and see where the power ends up, LOL.

On a side note, I have done a bit of racing out west (as a co-driver in the Brown Bros. Cobra R) and wondered what your times are at Portland. Just trying to get a feel for comparitive times for my car at that track. Just a shot of me at Mosport holding off a factory supported Saab 9-3 Turbo and a Golf with a VR6 and sequential style gearbox. We ran this close for over 2 hours.

Regards,

Eric Nummelin
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Old 12-30-06, 02:17 AM
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Smile Portland International Raceway

Sanction ICSCC PORTLAND INTERNATIONAL RACEWAY Last Race Sept 24th Weekend I Ran RS Class and the SPM Class just for fun
726 BC Mazda RX7 Red/Yellow 21 10 SCCBC CACC CANUSA Equipment Ltd Time:1:30.711 with the chicane.

I just modified a Gen one pinion gear on to my Gen two pinion shaft so I can run 4:88 gears. Also changed to a thicker cross flow rad. These will be the only changes to my car for this season coming up.

I think I met the Brow Bros. Ford guy. It's his son that runs and not the old man if I'm right.
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Old 01-02-07, 07:36 AM
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Thats pretty quick using the Festival chicane. Gives me a good idea where I would be, if I ever make the tow LOL.

THe BRown Bros. car is owned and run by Tim Brown. His dad hasn't been out to a race in over 20 years. More than likely you were talking to Don, one of the crew guys who acts like Tim's dad.

Anyway sounds like you have the car running great! I travel to Vancouver about once every couple of months and we should get together and swap war stories, etc....

Thanks,

Eric
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Old 01-03-07, 10:23 PM
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Smile I think I can get 5 to 10 more HP Cost $15/ 25 Hours Labour

Originally Posted by RICE RACING
^ what intake manifold you running? Thats some high revs for a NA street port (both peak power and tq)
Stock throttle body and intake system. But I ported the intake runners from the throttle body to the engine (As allowed be SCCA Regs.). Also I use a Mega Squirt fuel and spark system with a K&N air filter and 4 intake hose to the throttle body. Dyno runs show from 5200 RPM to 9000RPM 45 Deg. angle strait climb up no drop off. My street porting job I did myself with help from a racing friend. He has been in to racing rotary motor from the time the very first R100 engine came out. I play with street ports and he plays with three and four rotor peripheral port naturally aspirated engines.
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Old 01-06-07, 06:22 PM
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^ 3 and 4 rotors? Tell us more about your friend.
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