scathcart

Is anyone using these on their turbo engine build-ups?
I have always just used the standard oil springs.

I've recently picked up a set of the competition springs for use in my next build (N/A BP). They are visually the same size and shape as the regular springs.

Supposedly, they are a higher spring rate... the 1980 competition manual states that the spring rate was increased from 8 km/cm^2 to 13kg/cm^2. (outters only), and was used on their factory peripheral port engines. Thats a 62% increase in spring rate.
The stated reasoning was that the stock spring allowed for unsatisfactory levels of blowby.

On aviation builds and road racing engines running on wet-sump systems, blowby is fairly significant, especially with turbo applications. While these springs would obviously increase side housing wear, I am curious if anyone has used them to combat excessive blowby while running high boost?
These springs are not expensive... about $20 per engine, and the same price as regular oil control springs.

Searching on the subject has brought up no discussions, so I can't see this being a very commonly discussed or known about subject.

Any input?

coldfire

iTrader: (1)

i do know the old 80s Mazda GTU race cars (i think it was GTU series), ran fairly high premix ratios (enough to lower octane levels)...a higher spring rate could help combat the increase of blowby this would have caused. could be part of the reason maybe?
those cars were NA though

Turblown

iTrader: (12)

I figured I would give those a shot too. I plan on using a pressure transducer in the pan to measure the difference...

MrDirt

Speaking of "competition" parts... what is the difference with competition thrust bearings? I purchased them and got them in the mail, but I realized I never even knew what the difference was....

j9fd3s

iTrader: (3)

now this is just speculation, but maybe it helps keep the rotor off the side housing?

scathcart

Quite possible.

Like I said, it seems no one knows anything on the subject.

I'll report my findings after 20,000 kms or so.

Turblown

iTrader: (12)

Its definatly going to increase wear and drag. One would think it you would be better off just starting with perfectly parrallel sealing surfaces, instead of increasing spring pressure. Take a look at piston ring development over the years, same idea...

Although J9 does bring up a good point.

BLUE TII

iTrader: (9)

now this is just speculation, but maybe it helps keep the rotor off the side housing?

I know Racing Beat recommends running two sideseal springs stacked one on top of the other in high power applications to "help stabilize the rotor".

Since sideseals are closer to the outside of the rotor it would seem to me to have more effect of decreasing the chance of rotor to sidehousing contact than stiffer oil control seal springs; although, I am sure every little bit helps.

Anyone run two sideseal springs?

The stiffer oil control seal springs would probably be good for us turbo guys who get a bunch of pressure in the oilpan/sump.

One would think it you would be better off just starting with perfectly parrallel sealing surfaces, instead of increasing spring pressure. Take a look at piston ring development over the years, same idea...

Problem in the high rpm race rotaries is the e-shaft flexes since it is supported only on the ends and then the rotor isn't beings driven perpendicuar to the sidehousings. Just like piston guys we sure would benifit from more bearings; your shop should make some 2 piece e-shafts with center bearings like GURU ones.

That would solve so many of the rotary problems at once!

Turblown

iTrader: (12)

Well the more I think about it, I think those " race " oil control spring are just for preventing blowby.

Yes the Eshaft flexing is a definate problem in the higher hp cars,we just did a v12 here in the shop where the crank was bent.

I have already priced out doing custom Eshafts and such, and the prices are astounding. I have looked into doing what that RE shop did with their 4 rotor, a custom several piece Eshaft with bearings in the "center" irons inbetween in rotor.

T04Eneedy

astoundingly cheap,right? lmao

Turblown

iTrader: (12)

Try more than most people spend on an engine and turbo setup for 1 offs...

We do have a lathe, and a mill but we are not specialist in machining. I trust this kind a of work to other shop owners who are personal friends who have been doing this stuff for 40+ years. Who might I add do work for some of the fastest cars at the track and on the street in the entire world...

13btnos

iTrader: (1)

[QUOTE=BLUE TII]now this is just speculation, but maybe it helps keep the rotor off the side housing?

I know Racing Beat recommends running two sideseal springs stacked one on top of the other in high power applications to "help stabilize the rotor".

Since sideseals are closer to the outside of the rotor it would seem to me to have more effect of decreasing the chance of rotor to sidehousing contact than stiffer oil control seal springs; although, I am sure every little bit helps.

Anyone run two sideseal springs?
QUOTE]

I double up on side seal springs only on a race only motor. The spring rate tension when you double them up is considerably more. I would not do this for an engine that will see street use it does put alot more wear on the intermediate plates.

BLUE TII

iTrader: (9)

Thanks for the info!

I did not do this on my engine as I was worried about the stiffer spring rate from doubling up causing the sideseal to drop into the intake port more on my early opening sideport and causing more issues in wear and poor sealing from sideseal wear/damage.

re10

How many K's are you up to now?


I have them in my engine, mainly for the reason stated by RB - keeps the rotors stable at high RPM (9 or 10K rpm). Not sure what they are doing to the end plates, I think that I am just up to 4,000km's on this motor.

t-von

iTrader: (8)

These stronger oil control ring springs are recommended for high rpm's. I can see how the added pressure on the outer oil control ring with these stronger springs help keep the oil blow by down. I mean the higher the rpm's, the harder it is for the outer oil control rings to maintain control of the oil within the rotor and not allow it to blow by into the combustion chamber. To me this is obviously what they are designed for.

coldfire

iTrader: (1)

yup. i would imagine with very high premix ratios and high RPMs blowby becomes a significant issue...
although i do question the "reliability" wear of doing this on stock end plates. it's probably hard to justify for a street car...or at least MOST street cars.

t-von

iTrader: (8)

I don't see why everyone is so concerned about the end plates wear? The springs are 62% stiffer. So look at it this way. If a stock spring engine can easily go 200k with the side housing step wear still being close to within spec, I see no reason why an engine with these springs shouldn't easily last 124k. To add anyone that's properly rebuilt a rotary would know that the step wear on the outer oil control ring is hardly measurable. The inner oil control ring has always done more end plate damage. Don't sweat it guys.