If you know please chime in

IS there more stress on a 20B when:

Running it P-port with 10K revs

Or

on boost with a big single 8500 max revs

?

 

Depends on what you kind of "stress" you're talking about?

Ultra high RPM's induce frequency and vibrational stress which is different than load stress from big power.


-Ted

 

With under 20 psi boost I would say there is less stress on the boosted engine.
I've roadraced 1000's of kms without a rebuild. Not many pp guys can do that as the vibration causes water leaks around the devcon or filler used to fill the ports.
High rpm means high wear on bearings, apex seals, etc. Mazda states in their motorsports catalogue 8500 as a limit before things start to wear out exponentially. Not to mention the oiling requirements required. eg, high oil, pressure,dry sump,

 

I think the BLOCK itself is much more stressed on a big single turbo 20B. The rest of the engine (much cheaper, easier to get parts) are more stressed on ultra high rpm n/a. But if the engine is well balanced, clearanced, and ceramic seals with new rotor housings are used, its wear should be quite light.

Are you roadracing a 20B turbo?

 

yes, i even raced it at the Edmonton indy support race this year, where we blew the tranny. next year we'll have a Jerico 5 speed.
My friend raced a pp 3 rotor for 4 years and had more problems than me, alot of them related to the high rpm's.


there are some pics at www.edmontonrace.com of the car.

its the silver one, #222.

 

Also, I am way faster than any na 3 rotor.

 

I hope some day to prove you wrong

http://www.914world.com/bbs2/index.p...20b+peripheral

 

Cool car, good to see Rx-7's racing. However dont take this wrong, the way you describe your cars race history is on the short side? As in less than one race or season? Failure wise your friend had 4 years of racing? I am just curious mostly how you are keeping the turbo 20B cool on the track. The one you linked looked like a fast track, have you raced it on tighter courses for extended periods of time? Again not being mean, just you are the first I have heard of having no issues with a turbo 20B track car.

Well that is what typically happens when you put a turbo on the same engine

 

You are correct. This was only one full season with the 20b turbo.

But I have roadraced this car since 1997 and as a single turbo 13b (430 hp) since 2001. It took a few seasons to get the 13b turbo reliable in terms of cooling, fueling, tuning, etc., but it has been super reliable since 2003. A lot was learned over the last 6 years and that made going to the 20b less troublesome. I have no cooling issues!

My home track is Mission raceway, and it is the tightest track ever. Its mostly 2nd and 3rd gear, very slow corners( all 2nd and 1 third gear) . There are some guys with footage of their cars on youtube. type :mission raceway . Its tight!
All the races this year were in the summer and i had no heating issues. The key is a three pass Ron davis radiator, and THREE big oil coolers!(fluidyne) . And the rad is not obstructed by the intercooler. I started with two which almost worked, but this is a slow track. We ran it rich at 11.2 :1 just to be safe. Shifted at 7500. The tune was set at two boost levels. 14psi netted 590 rwhp and 18 psi netted 664 rwhp. I never raced it at higher than 14psi as it was already too much power for the stock tranny.

In the Edmonton race we qualified last due to a sheared tranny input shaft during Q1. We started the race last and got as high as 7th before a big crash cut the race short. I was very gentle with the throttle as the track was bumpy off a few corners and I didn't want to break again. Hopefully they'll have it again next year.

For 2008 i'm going mazdaspeed dry sump in hopes of going back to two oil coolers, penske shocks (done), and jerico 5 speed with tilton 3 disc.

wouter

 

Were you using the stock water pump or an electric setup?
Have you tried Evans coolant?
Mind sharing a few pics of the ic/rad/ducting setup?

 

I used a stock fd water pump. My friend with the 3 rotor pp used evans and swears by it but since I haven't had any problems it seemed like another expense that i didn't need. He used a stock water pump with large pulleys.

I have heard the stock water pump will cavitate at rpm's over 7500 so that may affect some engines.

I've never been successfull at posting pics. I am not great with the computer. The car is in pieces so there aren't too many pics available until spring.

wouter