Polishing Rotors - Pros and Cons

NoDOHC · 03-01-2009, 11:47 PM

Right now I am in the act of freshening up an 88 4-port engine for in my '86.
I have seen many people polish the rotors before installing them, I decided to do the same.

The reasoning that I used is that it will decrease carbon buildup, improve heat rejection of the rotor and decrease exposed surface area which should minimize fuel precipitation and improve knock resistance.

My question here is whether the rotor requires some irregularities for improved turbulance as the air exchanges past the point between the leading and trailing plugs (right before it ignites the charge). Will polishing the rotor sacrifice startability and low-end toque by eliminating an important fuel mixing mechanism?

Maybe this question has yet to be researched. I only brought it up because I can't decide myself if it will improve flow or harm it.

I went ahead and polished the rotors, so I can only hope there are no negative side effects.

Whizbang · 03-01-2009, 11:48 PM

it theoretically should help keep carbon build up down for sure, which can keep hot spots from forming on the rotor.

RETed · 03-02-2009, 12:47 AM

They come coated from the factory.
Polishing them just just got rid of that special coating.
I don't bother, except to knock off all the crud.
No on see them once the motor is assembled anyways.

-Ted

NoDOHC · 03-02-2009, 06:53 PM

I wouldn't have polished them if I knew that they were coated, they looked like rusted metal to me.

I hope I don't regret that.

N.RotaryTech · 03-03-2009, 08:04 AM

Do you have pictures?

To_Slow · 03-03-2009, 08:50 AM

Here some pics i did for a 3 rotor custo couple off years back...

Regarding benefits by polishing the rotors, it will help with carbon build up control in theory . How much i really do not know. That 3 rotor i did for that custo is not do for a rebuild yet. I will also be interested to se how much it helped with the carbon control or if any at all. From looking at the first pic you can se how much carbon the rotor had on it

...

Whizbang · 03-03-2009, 12:52 PM

isnt there some kind of coating you can get on the rotors too now a days?

My5ABaby · 03-03-2009, 02:23 PM

Quote:

Originally Posted by Low Impedance

isnt there some kind of coating you can get on the rotors too now a days?

Cermet.

charlies7 · 03-04-2009, 01:19 AM

Swaintech also provides a high temp coating for rotors..Ceramic based.

Quote:

Originally Posted by My5ABaby

Cermet.

Whizbang · 03-04-2009, 01:21 AM

ah there we go! what company does the service?

Atkins Dan · 03-05-2009, 05:08 PM

Quote:

Originally Posted by RETed

They come coated from the factory.
Polishing them just just got rid of that special coating.
I don't bother, except to knock off all the crud.
No on see them once the motor is assembled anyways.

-Ted

This coating from the factory is just a anodize usually gold or green in color..
So depending on how harsh {or strong} the chemical you use to clean the rotors with, it will take it off anyway..

Dan

RETed · 03-05-2009, 10:52 PM

I've never seen anodizing appear like that.
I've never heard of any anodizing internal engine parts.
I've never heard of anyone anodizing steel / iron - only aluminum?
I don't think the rotors are aluminum.
Cadmiun perhaps?
SAE papers claims it's a special coating for oil adhesion.
It's on the rotors faces + on the outside edges of the rotor from the side seal groove to the edge of the rotor faces.

-Ted

Atkins Dan · 03-05-2009, 11:42 PM

Sorry Ted I ment cadmium plating on the rotor... On the other coating there is a small amount of teflon {I think} on the outside edge of the side seal on the rotor its self...

For a coating on tub side of the rotor it may be there but i have never seen it on brand new rotors {Rx7 or 8}

If you don't mind can you post a link or scan the SAE papers you are reading???

Dan

NoDOHC · 03-15-2009, 10:47 PM

A few questions:

What would you call this? (Street port? Stock port?)
Primary Port.JPG
Secondary Port.JPG

The intention was to avoid changing port timing while providing a nearly consistent cross-sectional area for the primary and secondary runners and ports. I am not sure if this is still a stock port due to stock port timing or if it is considered a street port.

Here is a picture of the finished rotors (I would post more, but it is too much work resizing them).
2 Rotors.JPG

Atkins Dan · 03-16-2009, 09:05 AM

in my mind that is a street port..

as for the rotors good job and it looks good too..

Dan

03-01-2009, 11:47 PM	#1
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	Polishing Rotors - Pros and Cons Right now I am in the act of freshening up an 88 4-port engine for in my '86. I have seen many people polish the rotors before installing them, I decided to do the same. The reasoning that I used is that it will decrease carbon buildup, improve heat rejection of the rotor and decrease exposed surface area which should minimize fuel precipitation and improve knock resistance. My question here is whether the rotor requires some irregularities for improved turbulance as the air exchanges past the point between the leading and trailing plugs (right before it ignites the charge). Will polishing the rotor sacrifice startability and low-end toque by eliminating an important fuel mixing mechanism? Maybe this question has yet to be researched. I only brought it up because I can't decide myself if it will improve flow or harm it. I went ahead and polished the rotors, so I can only hope there are no negative side effects. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

03-01-2009, 11:48 PM	#2
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp Posts: 3,190 Rep Power: 20	it theoretically should help keep carbon build up down for sure, which can keep hot spots from forming on the rotor. __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

03-02-2009, 06:53 PM	#4
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	I wouldn't have polished them if I knew that they were coated, they looked like rusted metal to me. I hope I don't regret that. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

03-03-2009, 08:50 AM	#6
To_Slow Rotary Fanatic Join Date: Feb 2008 Location: Shelby Twp MI. Posts: 315 Rep Power: 18	Here some pics i did for a 3 rotor custo couple off years back... Regarding benefits by polishing the rotors, it will help with carbon build up control in theory . How much i really do not know. That 3 rotor i did for that custo is not do for a rebuild yet. I will also be interested to se how much it helped with the carbon control or if any at all. From looking at the first pic you can se how much carbon the rotor had on it... __________________ My link Last edited by To_Slow; 03-03-2009 at 08:53 AM.

03-03-2009, 12:52 PM	#7
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp Posts: 3,190 Rep Power: 20	isnt there some kind of coating you can get on the rotors too now a days? __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

03-03-2009, 08:04 AM	#5
N.RotaryTech Home-brew Rotary Join Date: Feb 2008 Location: GooseCreek SC Posts: 552 Rep Power: 18	Do you have pictures?

03-04-2009, 01:21 AM	#10
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp Posts: 3,190 Rep Power: 20	ah there we go! what company does the service? __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

03-05-2009, 11:42 PM	#13
Atkins Dan Premium Vendor Join Date: Feb 2008 Posts: 265 Rep Power: 18	Sorry Ted I ment cadmium plating on the rotor... On the other coating there is a small amount of teflon {I think} on the outside edge of the side seal on the rotor its self... For a coating on tub side of the rotor it may be there but i have never seen it on brand new rotors {Rx7 or 8} If you don't mind can you post a link or scan the SAE papers you are reading??? Dan __________________ 82 SuperCharged rx-7 {my toy not the daily driver anymore now under restoration} 88 B2200 rotary powered with a 7inch Camden SuperCharger !RIP! Jan/4/2007 2001 626 5-speed 80k on the clock all stock {Truck replacement} 2005 MAZDA6 V6 WAGON now that is a pimping ride all stock for the moment.. Paid off WWW.AtkinsRotary.com

03-15-2009, 10:47 PM	#14
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	A few questions: What would you call this? (Street port? Stock port?) Primary Port.JPG Secondary Port.JPG The intention was to avoid changing port timing while providing a nearly consistent cross-sectional area for the primary and secondary runners and ports. I am not sure if this is still a stock port due to stock port timing or if it is considered a street port. Here is a picture of the finished rotors (I would post more, but it is too much work resizing them). 2 Rotors.JPG __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

03-16-2009, 09:05 AM	#15
Atkins Dan Premium Vendor Join Date: Feb 2008 Posts: 265 Rep Power: 18	in my mind that is a street port.. as for the rotors good job and it looks good too.. Dan __________________ 82 SuperCharged rx-7 {my toy not the daily driver anymore now under restoration} 88 B2200 rotary powered with a 7inch Camden SuperCharger !RIP! Jan/4/2007 2001 626 5-speed 80k on the clock all stock {Truck replacement} 2005 MAZDA6 V6 WAGON now that is a pimping ride all stock for the moment.. Paid off WWW.AtkinsRotary.com