Rub20B

Hello,

I just opened up an engine from a customer, it has been rebuilt 50 k km ago with new out of the box rotor housings. the reason for pulling the engne was that the rear rotor lost compression on 2 faces. the car is a S5 TII convertible, running stock turbo and just a tune, with afrs below 11 at wot. around 0.7 bar boost.

Found out the tip of an apex had broken off for unknown reason

after pulling the engine we found out the seals where something I had never seen before. the have a really wide tip section (is it only me or do others also think this will only work when the apex width is perfect for the housing width (which defeats the use of dual piece seals anyway)?? if the length doest not match there will be directly a huge non sleaing surface due to the very wide tip section?) to make it all worse, where running only single spings!!

the housings also look like they have been in alot of pain due to apexes, the have feelable grooves over the entire width, which feel worse than the look, more apperant in the exh stroke part of the housing. they will be re-used but still.

I have torn apart engines with 3 times the mileage with mazda seals with silky smooth surface.

Could it be the OMP is not working properly causing this wear? there appeared to be oil in the lines and there is no limp mode or cel, or is it just the seals which suck ***

GoodfellaFD3S

iTrader: (213)

I could have told you this back in 2000. The Hurley seals (specifically their 'long life racing' 2mm seals) are complete garbage. I've posted about it numerous times over the years. If you let out a nasty fart while WOT, they'll break.

peejay

In my opinion, ALL non-Mazda ferrous seals need more oiling than Mazda seals require.

I have good luck with Atkins seals, but I premix (no OMP) at the rate of about 80:1 with Lucas oil. There's a noticeable gain in smoothness and power over the 128:1 that people talk about, which is more of a convenient mnemonic (1ounce per gallon) than anything.

The OMP oils at the rate of about 150:1 at its richest to 400-500:1.

Rub20B

I see..

also the engineering behind it makes no sense at all to ne, a wide tip section has nothing but disadvantages, especially when running only a sngle spring..

also the 'legs' of the apex preventing the spring from walking out to the side are just 90 deg corner, no radius, nothing.. as every mechanical engineer should know, no radius is bad, it creates stress concentration and more risk for fatigue failing of the tip

bo0557

iTrader: (1)

Yesni concur they are a piece of **** from personal experience but the advice of the engine builder in the first place didn't help.. True story that!

Rub20B

ported the plates and housings and started rebuilding it tonite and will close it tomorrow, will re use side and corner seals, use new oil orings and oem mazda 2 piece seals and springs.