i recently polished a set of 9.7:1 rotors that will be used in my fd.

just a quickie on what i'm trying to do here-- 350-375whp awesome street/twisty car. it was gonna get a cosmo motor, but i can't afford that right now, so it'll have to be the rew...for the time being anyway. gt35/40 dbb turbo, front mount and all the standard supporting mods, etc... ems will be a haltech e8. i want quick spool, good low end, great drivability, etc...if i wanted power, i'd do another bridgeport with a pt67 or something like that...



so now you know what i'm planning here, on to the polishing. my idea behind it is obviously give the rotor a smooth face--a face that carbon will have a hard time sticking to. no doubt this will be the case, but when i was dropping the rotating assembly off at mazada trix to get balanced, a question (suggestion, comment?) was brought up about fuel atomisation.



we all agreed there probably wouldn't be much of any carbon buildup on the rotors, but it was suggested that some of the fuel might drop out of atomisation and cling to the face of the rotor. gas milage is definately a concern with this motor (that's why i'm sticking with a mild primary/ medium secondary streetport). my (i guess you'd call it argument) is the combustion is going to be hot enough to burn it all up (i hope)...not like the fuel clinging to the sides of super-smooth ports.



i'm gonna use them just to see what the story is--i can always rough them back up. but anyone have any experience with the pros and cons of highly-polished rotors?



thanks[attachment=32859:attachment][attachment=32861:attachment][attachment=32860:attachment]

[quote name='guitarjunkie28' date='Jul 26 2005, 12:22 AM']i recently polished a set of 9.7:1 rotors that will be used in my fd.

just a quickie on what i'm trying to do here-- 350-375whp awesome street/twisty car. it was gonna get a cosmo motor, but i can't afford that right now, so it'll have to be the rew...for the time being anyway. gt35/40 dbb turbo, front mount and all the standard supporting mods, etc... ems will be a haltech e8. i want quick spool, good low end, great drivability, etc...if i wanted power, i'd do another bridgeport with a pt67 or something like that...



so now you know what i'm planning here, on to the polishing. my idea behind it is obviously give the rotor a smooth face--a face that carbon will have a hard time sticking to. no doubt this will be the case, but when i was dropping the rotating assembly off at mazada trix to get balanced, a question (suggestion, comment?) was brought up about fuel atomisation.



we all agreed there probably wouldn't be much of any carbon buildup on the rotors, but it was suggested that some of the fuel might drop out of atomisation and cling to the face of the rotor. gas milage is definately a concern with this motor (that's why i'm sticking with a mild primary/ medium secondary streetport). my (i guess you'd call it argument) is the combustion is going to be hot enough to burn it all up (i hope)...not like the fuel clinging to the sides of super-smooth ports.



i'm gonna use them just to see what the story is--i can always rough them back up. but anyone have any experience with the pros and cons of highly-polished rotors?



thanks[attachment=32859:attachment][attachment=32861:attachment][attachment=32860:attachment]


[/quote]





Not a factor.



Rotor face temps are in the 300 degrees and up zone.



Polished is fine as it very slightly reduces the total area exposed. It looks good.

It shows that you cared enough to do it right. There is a difference in power output,

but it would take a good dyno operator to detect it.



Paul Yaw polishes his rotors, so it must be a good idea.





There is a bunch of hand work involved. The more you screw with each rotor the more likely it is that one may be damaged. There are other time conusuming things you could do to get more power per unit of time spent.



Beyond that, polish everything. It looks good.





Lynn E. Hanover

[quote name='guitarjunkie28' date='Jul 26 2005, 03:22 AM'].... was brought up about fuel atomisation


[/quote]

have the same concern...

preventin carbon build up was my main reason for the polishing as well...

although did not take into consideration fuel mixture until after the fact...

[quote name='Lynn E. Hanover' date='Jul 26 2005, 07:23 AM']Not a factor.



Rotor face temps are in the 300 degrees and up zone.



Polished is fine as it very slightly reduces the total area exposed. It looks good.

It shows that you cared enough to do it right. There is a difference in power output,

but it would take a good dyno operator to detect it.



Paul Yaw polishes his rotors, so it must be a good idea.

There is a bunch of hand work involved. The more you screw with each rotor the more likely it is that one may be damaged. There are other time conusuming things you could do to get more power per unit of time spent.



Beyond that, polish everything. It looks good.

Lynn E. Hanover


[/quote]





I love a good back handed compliment! https://www.nopistons.com/forums/pub...1047683785.gif

well cool then https://www.nopistons.com/forums/pub...IR#>/smile.png



these ended up being 9.5:1 compression when i was done with them.

an afternoon of boredom, tools, and a graduated cylinder...



now if mazada trix would hurry up and get ti balanced, i cna put it all together.



thanks for the input.

Ive done it on 3 rotary engines so far. Did it to the point that you could see your face in it clearly. Nothing but what you would expect.



You may also want to check the distance from the apex groove to the beginning of the combustion dish(both sides). On the s4 I have measured up to 8mm out of time.



Pretty much the same result I got when I did it on piston engines. Piston guys have been doing this for years. Ive always wonderd why rotary builders have not picked up on it. Guess it goes to show how many piston engines most rotary guys have built.



Really there are no cons on this one unless you consider the hastle of polishing it. https://www.nopistons.com/forums/pub...1047683473.gif

that's about what i was thinking, but i figured i'd gather opinions on it--since the old man at mazdatrix seemed pretty dead-set against it.



but then again, he said beveling or radiusing the sides of the rotors was a terrible idea because it would allow combustion gasses to get past the side seals...maybe someone should have told mazda that before they made the rx8 rotors that way... https://www.nopistons.com/forums/pub...>/rolleyes.gif

[quote name='GMON' date='Jul 26 2005, 01:15 PM']Ive done it on 3 rotary engines so far. Did it to the point that you could see your face in it clearly. Nothing but what you would expect.



You may also want to check the distance from the apex groove to the beginning of the combustion dish(both sides). On the s4 I have measured up to 8mm out of time.



Pretty much the same result I got when I did it on piston engines. Piston guys have been doing this for years. Ive always wonderd why rotary builders have not picked up on it. Guess it goes to show how many piston engines most rotary guys have built.



Really there are no cons on this one unless you consider the hastle of polishing it. https://www.nopistons.com/forums/pub...1047683473.gif


[/quote]



ive done it too. i've measured a few sets of s4 rotors, and they really are all over the place. ive just been picking the best pairs.



the set i polished was quick to do, i took some 400grit sand paper and just did the face, i left the combustion recess alone as i dont have the tools to get them consistent. the faces shine up real quick

what did you use and how did you polish them?

what i did use is not exactly the same as what i will use in the future.



combustion chambers were done witht he die grinder and sanding wheels. faces were done with 800 grit hand sanding, then i buffed the whole **** out on my ghetto grinder with the polishing wheel attached.



in the future, i'm gonna try faster methods to try to get the "bathroom mirror" finish on it, but it's good enough so you can hold a piece of paper next to it and read the text clearly.