Marcel Burkett

Can someone please shed some light on the above , like how it is done , by whome , the cost and if this mod .would make sense in a 13bREW engine with stock internals (ie .stationary gears , e. shaft etc).

amemiya

yeah atkins say you need race clearancing to go to 10,000 rpm. So what is done to the motor for this race "clearancing"

HWO

you need race clearancing on the rotors if you go over 500HP and or 8000rpm. I belive it is simply milling 0.2mm off each end of the rotor (top and bottom) this makes the rotor slightly thinner so it cannot impact with the end and side plates.

Kiwi NZ

HWO

Do you race clear your rotor bearings?

soul assassin

i don't think it makes to much difference, my old motor was not clearanced niether was the 600 ps fd and you could tell that it clipped the side plates and wore down but no major damage and the end plates were reusable

Marcel Burkett

I am rebuilding and modifying right now , I am going half bridge with a T66 @ 18 to 25 psi hoping to be in the 500bhp range , rev cut to be at 8500 ,do I need to do this ?

peejay

shouldn't this be in the rotary performance section? it's not single turbo specific...

Marcel Burkett

O.K. Peeeeeeejay .....................sorry, will do .

RICE RACING

It is totaly correct...

The amount of "flex" is proportional to wieght of the rotors/RPM/& chamber Pressure.

It is 100% common that a 13B with series 5 or 6 rotors will hit side plates regarless of how high oil pressure you run when making 500BHP upwards and using 8000+rpm. It costs power and reduces engine life, Most experienced circuit engine builders clearance engines to get maximum reliability and power.

The Japs from what I have seen in some shops only clearance the tips near the corner seal (very gay method) I clearance the whole rotor side down to the "land" (proper way)

Rotors are not designed to rub against side plates in this region, If you notice this wear upon tearing down your engine (assuming it was operated within your engine builders rev limit and did not loose oil pressure) it is a sure sign of the lack of experience your engine builder truly has in relation to this subject and does not know its ill effects.

My 0.2c worth.

soul assassin

i agree with you to a point (as usual)
they do only do the corner here by the corner seal
no biggie gay or not could not tell ya.
my thing is if it smacks the housing a little bit who cares
who builds 500+ hp engines for longevtivity? as long as you do a rebuild eveyr 50 k or so you should be fine. I mean honestly how much power are we talking about losing here, >5 hp most likely

amemiya

If you are going to rev cut at 8500 rpm than don't even do a bridge port, a street port can pull to 8500 no problem, the only advantage a bridge would give you would be qiuck turbo spool.

Maxthe7man

I am starting to think this is just one of those Buzz phrases added to the bill to justify a few more dollars and an attempt to add crediblity to the rebuilder..
Its like pistone engines, how many are sold as balanced and blueprinted, and how many were.. Real blue printing takes a ton of time, and with the turn around time shops are under for engines, I don't think to many are really "race clearancing" the rotors, they might check the clearnace but for actually changing it, I doubt it.. Its one of the things thats kinda unproveable on teardown,if the engine eats its seals real bad anyway..Max

Ps: Hey soul that avatar is kinda creepy..

RICE RACING

It is the easiest thing to pick on tear down !!!

The sides of the rotors have machining marks on them, and you will not see the factory stampings on the sides.

I do not doubt that some un proffesional builders charge for **** they do not do (fact of life unfortunatley) but like all things they eventually get found out to be the rip off artists they are.

The mod is very benificial it is worth quite a bit of power, and reduces stress alot, in quite a few areas......If you e-mail me I can elaborate on the many benifits. Also it is not only the rotor sides that touch but also the faces that hit the rotor housings, as I said Professional engine builders who get every last ounce of power and reliability from their engines know of all of these problems in High HP rotaries.

If you pull the engine apart and it has any shiny spots on the rotors near the tips or on the faces from hitting the rotor housings it is bad news and is not normal. It is costing you power in the region of around 5% and greatly increases stress on the whole engine (dowel, crank, stationary gears...the list goes on) Maybe that is why some drag guys rebuild engines so very often, I have always found it pretty amazing the lack of engine preperation done by some engine builders

Maxthe7man

yeah thanks Rice, check your email.Max

rotarygod

iTrader: (1)

A fairly unknown by many trick to help avoid contact between the rotor faces and the side plates without clearancing is to use 2 side seal springs stacked on top of each other. It does add friction though and will ultimately shorten usable engine life but so will contact between the two parts. It is a technique that racing beat mentions in their newest catalog. It does not guarantee no contact but neither does clearancing. The problem is the e-shaft flexes at high rpms. Jeff Bruce, the guy from New Zealand who built Hitman's engine custom makes e-shafts with center bearings and also mods the intermediate housings for a bearing. This stops the e-shaft flex and supposedly allows 12k plus rpm with no contact and no clearancing. Your bearings probably will die at that speed though.

soul assassin

thats some good info! i know over here in japan they make 3 piece e shafts for a pretty penny

Marcel Burkett

Ay Rice can you go into a bit more detail about the subject ? , how can I have it done down here ? should I go to a machine shop and tell them to skim the rotor sides and faces?.

soul assassin

not the faces!!!

RICE RACING

Any competent machine shop can do the job correctly, rotor sides require generaly around 0.2 to 0.3mm extra to be removed from each rotor side (except the rotor land's) this will increase the clearance that normaly is there to a total of around 0.5mm on each side. If the rotor is worn (many are) then there will be wear on each land wich has reduced the clearance that was there from new, in which case you need to machine more of the side to get the clearance you will require... This is very common in engines that have been rebuilt with refinished end plates or engines running mineral oils which accelerate wear on cold start up on these bearing lands, it is very common to find below factory clearances.

There is no problem with clearancing rotor faces, this can be done by hand believe it or not and will require partial assembly of the engine to measure rotor face to rotor housing clearance, with time and accurate marking and a steady hand you will be able to remove around 0.1 to 0.2 mm from these areas in question (a machine shop will not be able to do this for you) as it depends on the engine and parts condition combination to get the right clearance. It will not reduce the strength of the rotor face to any great degree Infact after you eliminate rotors hitting **** "everywhere" you may find you never have rotor based reliability problems again

Note, the amount of material moved during al these operations is Very small in overall weight, less than when you go from 2mm to 3mm apex seals and no rebalance is required.

Marcel Burkett

AY RICE , I am not trying to sound like a nubie or bug you or anything , but down here this sort of thing is completely new , we just change out seals and any damaged parts then re - assemble.I want to run 9000+rpm safely so I want to do it correctly so please bear with me , ok , so the LANDS as you call them , are they the cast circles (which protrude a bit ) between which the oil control rings go on the sides of the rotors ? .

3rdGen7

Please donīt make us sound dumb ..anyone can do this

...just having fun

Marcel Burkett

3rdGen7 ............., why dont you stay off the ****** thread if you dont have a worthwile contribution to the topic of discussion , I want no beef with you (or any one else for that matter ) so please stop the **** , I am here to learn , contribute when I can and enjoy being a member , o.k. !!!.

3rdGen7

Marcel,

..why do you want to go all the way to 9000 RPM ..you'd probably be way past your usable / peak torque ? ...i.e you won't be accelerating anymore at this point.

Marcel Burkett

I want to go that high because I am going to be running a half bridge ported motor , power band and torque are lifted higher in the rpm range.

Freaky Monkey007

I too would be interested in what all is required to get anything above 9k rpms...

So the race clearancing is basically sanding down the rotor to allow the e-shaft to flex at those high rpms?? Correct? So if you were to buy a new e-shaft that doesnt flex as much would you have to race clearance ur rotors?