Hi all, Just want to ask all you Bridge People what tips u recomend?

I will be staying with 2mm and have done a bit of reserch into the mater, We have Hurley very close to us hear and its very tempting to use there Racing Tips but is this possable with a Bridge?
I have had my local Racing Beat dealer trying to put me of Bridgeing my car as i cant use 3 peice tips, Is this right?

Thanks

 

I have just spent about an hour reading all the posts on tips. There has ben some long discutions on the tips Stock or Hurley? stock are 3 piece but are slightly harded and have been alot beter developed but Hurleys are made to be used with there Rotor Tip oiler mod .

The thing that i want to know more than anything is can i fit Stock or Hurley tips to my Partail Bridge Engine? With out any problems?

Also is it true that Hurley tips are alot softer than Stock and there for wear out quicker?

 

The theory behind softer seals is that they don't damage your rotor housings at all. THis is why carbon seals are soo good, so you can almost reuse your rotor housing indefinitely! ..assuming you never let your seal get so thin and breaks, thus ruining your housing. Infact I dissassembled my bridgeport only to find they looked like new, and there was negible loss of material in the thickness, granted it had less then 2K on it. It is much, much lighter then steel hence, seals better above 7K because it has less interia to keep it in contact with the rotor housing were steel would be bouncing around a lot more.

 

On a Bridge port is it better to use 2 or 3 peice tips?

Would i have any problems if set up properly runing std Apex tips?

Thanks.

 

I don't know. I own 1piece apex seals?

 

WackyRotary

Would you happen to know the clearances on 1 piece steel apex seals?

 

I don't know anything about 1piece steel seals. However I believe Mazdatrix makes one-piece seals but they are oversized so you need to ground them down to whatever length you need. I don't know how clearences your looking for. Do you mean 2mm vs. 3mm? I think they are 2mm though. But I don't know how good theses are for longevity/sealing/etc/etc even though they are steel.

 

Yeah whats the diff between 1 2 and 3 piece seals, and what about number of springs?
I never really understood, and they look all odd w/ the slanted piece on the end of the seal on some of em
ahh!!!
anyone care to explain

 

Ok Node: pre 1985, all engines made for a production by mazda were all two piece seals. They were either 70mm long by 3mm thick for a 12a and 80mm long and 3mm thick for 13b. Both were shaped like a
knife sorta near one end. Then a small triangluar end piece fit in the void on the end. Then a sring was put underneath it pushing against the rotor groove.

1986+ were all 3 peice seals and all 13b configuration. One major change is they are all now 2mm thick, every engine, unless you modify it. Completely new design..almost. Two long narrow pieces and one corner piece simialer to earlier design. Also springs are different a smaller one and a longer one are utilized. One reason for the change was better sealing between rotor faces. It does nothing for power, but was able to get better emissions. Thats the primary reason Mazda did it. 3mm design is slightly more durable, however, unless you have a engine making 600+turbo boosted hp, 2mm is probably fine.

 

Stress Testing on 2mm 3 piece STOCk apex seals done by RICE RACING shows that the stock seals can withstand around 1200HP before breaking from shear HP pressures

 

I am sure Rice Racing wasn't considering levels of safety, they just wanted to see what it could withstand right? So 1200hp is max? I like seals that are thick so they have more time to get worn down. Also the surface area touching the rotor housing is greater in a thicker seal and less pressure is being pushed into a small area.. Usually thicker means more durable to detonation and withstand some more abuse without failing as quick maybe. Personally 2mm is fine as long as you don't pull near a record level HP then right?

 

Think about that... first of all, given that apex seals have rounded ends, the difference in contact area between a 2mm and a 3mm seal is going to be so small that it's not worth measuring.

But the 3mm seal will forced harder against the rotor housing because of much greater weight, and since combustion pressure under the seal is what does the "forcing", you can easily see that there is 50% more surface area for the gases to force against (160mm^2 for 2mm vs. 240mm^2 for 3mm).

That's how Mazda has been able to reduce OMP volume.. they don't need as much.

 

I think the OMP from carb'd engines were rough and more levels of safety was the reasoning for more oil being added to the mix..better safe then sorry:Mazda's thoughts on that at the time. The 84-85 GSL-SE which ALSO utilizes 3mm apex seals uses less oil injected in compared to the 3mm apex sealed 12a engine for the same year because of refinements to the oil metering system partially responsible by being moved to the rotor housing itself and not being directly mixed into the gas and Mazda deciding to be more presise to the engines apex seals needs. I have a manual showing what they inject infront of me:

12a engine '81-85: 1.8-2.2cc/6min
13b engine '84-85: 0.8-1.2cc/6min

Both use 3mm thick seals, so its not injecting more oil because its simply 3mm seals...

 

For what it's worth, 12As didn't mix it into the fuel, it just looks that way because the OMP lines go to the carb. Actually what the lines go on to are simple tubes that go to the venturi, and the oil drips out from there. (I have a pair that I pulled out from a junk carb in preparation for modifying a Holley to accept the OMP lines) At high speed the oil actually gets atomized in the air stream. It's a good point you make that the -SE engine made do with less injection because of more accurate distribution, however the later engines used still less oil, and stressed the engines further because they made more power in both non turbo and turbo form.