Engine teardown - 300+ hp with highish miles
03-12-2013, 02:10 PM
#77
interesting. there are three corner seal springs. the wire type (1202-11-323A), used from the beginning until the early 90's.
with the JC cosmo engines they introduced the NF01-11-C24 seal spring, its much stiffer, and much more durable.
interestingly with the Rx8 they have a 3rd spring, N3H1-11-C24B, which is like the FD spring, but apparently with less tension.
so perhaps Mazda already gave the Rx8 less corner seal spring, and when you up the power more, it wants even less?
with the JC cosmo engines they introduced the NF01-11-C24 seal spring, its much stiffer, and much more durable.
interestingly with the Rx8 they have a 3rd spring, N3H1-11-C24B, which is like the FD spring, but apparently with less tension.
so perhaps Mazda already gave the Rx8 less corner seal spring, and when you up the power more, it wants even less?
It's a pretty bad recipe .....
Last edited by Brettus; 03-12-2013 at 03:20 PM.
03-12-2013, 02:14 PM
#79
SARX Legend
iTrader: (46)
I think this is why so much attention needs to be taken when cutting the seals. Did you use precut seals on this engine when it was rebuilt last time or were they cut by the builder?
03-12-2013, 03:09 PM
#82
SARX Legend
iTrader: (46)
Well it seems to me if they were not cut to tight tolerances then carbon could build up where you don't want it and then cause the side seals to stick and cause damage and wear out prematurely. 
03-12-2013, 06:46 PM
#85
"I think you may have more turbo back pressure than you think? Maybe? Pressure/expansion under the seals could cause the seal to catch on the exhaust port."
Ahem..........cough, cough, cough")
Don't dismiss the hot spots around the plugs. That has to be addressed if you want longevity. There are specific things that you can do to increase the cooling to those areas.
Omp has to be used to get the max out of the side seals--pre mix doesnt fix the lack of omp injection---i feel like I am preaching to the choir here....bret knows these things already--sorry man.
Ahem..........cough, cough, cough")
Don't dismiss the hot spots around the plugs. That has to be addressed if you want longevity. There are specific things that you can do to increase the cooling to those areas.
Omp has to be used to get the max out of the side seals--pre mix doesnt fix the lack of omp injection---i feel like I am preaching to the choir here....bret knows these things already--sorry man.
03-13-2013, 01:33 AM
#88
I'll take pics of it for you tomorrow if I remember. Pineapple does this, mazmart does a variation as well. Shoot even the factory casts have some cut out that dip on an angle to slow water flow... Basically we just improve on what the factory was going for.
I have pics of the exhaust ports as well if you want to see them ill try and upload them.
03-13-2013, 11:37 AM
#89
if i can make a recommendation, its to tap a fitting into the exhaust manifold and look at preturbo backpressure.
you don't need anything fancy to do monitor it, a boost gauge works fine.
i did it on the last car i really went after methodically, and its very informative.
you don't need anything fancy to do monitor it, a boost gauge works fine.
i did it on the last car i really went after methodically, and its very informative.
03-13-2013, 11:53 AM
#90
The only problem with all of this is if he wasn't to reduce manifold pressure he will need to get a larger turbine which will increase spool times.
The 20G greddy turbine wheel is almost perfect, as far as size spool times goes.
The only other opportunity to gain more flow would be to convert the downpipe to a true 3" setup. I am still working on that but wont have anything done till the end of the year.
The 20G greddy turbine wheel is almost perfect, as far as size spool times goes.
The only other opportunity to gain more flow would be to convert the downpipe to a true 3" setup. I am still working on that but wont have anything done till the end of the year.
03-13-2013, 12:51 PM
#91
The only problem with all of this is if he wasn't to reduce manifold pressure he will need to get a larger turbine which will increase spool times.
The 20G greddy turbine wheel is almost perfect, as far as size spool times goes.
The only other opportunity to gain more flow would be to convert the downpipe to a true 3" setup. I am still working on that but wont have anything done till the end of the year.
The 20G greddy turbine wheel is almost perfect, as far as size spool times goes.
The only other opportunity to gain more flow would be to convert the downpipe to a true 3" setup. I am still working on that but wont have anything done till the end of the year.
Last edited by j9fd3s; 03-13-2013 at 12:54 PM.
03-13-2013, 03:20 PM
#93
if i can make a recommendation, its to tap a fitting into the exhaust manifold and look at preturbo backpressure.
you don't need anything fancy to do monitor it, a boost gauge works fine.
i did it on the last car i really went after methodically, and its very informative.
you don't need anything fancy to do monitor it, a boost gauge works fine.
i did it on the last car i really went after methodically, and its very informative.
Gunna just throw this out there
The blurb from pettit suggests that they see this a LOT . They also say the cause is from turbos set to run at much higher boost than the stock 'assume Greddy' system was designed to run therefore backpressure blah blah blah.
I will put it like this - very few Greddy kits ever ran anywhere near the boost level (particularly at high rpm) that I ran on my car or got the miles i did for that matter . I wonder how many of the engines they see saw track time ? Maybe that was a big factor in the failure rates ?
Last edited by Brettus; 03-13-2013 at 04:17 PM.
03-13-2013, 03:26 PM
#94
I already know there is a LOT of backpressure due to the lengths i had to go to to get decent boost at high rpm . I'm not 100% convinced that this issue is caused by the backpressure or whether it is just a factor that exacerbates it . We need a high mileage teardown from a SCd car to verify that they don't have it as well.
03-13-2013, 06:17 PM
#99
Pettit has seen a LOT of turbo renesis engines. Not high mileage ones, but the ones from the Diaso track cars. Pettit is the supplier of engines to this model. He identified this issue back in 2008? Maybe?
I know my engines were not high mileage under boost engines (25000miles max)--but none of mine had any markings like that. My engines were ran pretty hard due to multiple track sessions--even in 105F ambient weather. SWEAT
Cam even recommends to not wrap or ceramic coat your header ( oem or aftermarket). He told me that the rear rotary exhaust port has more trouble cooling and a coating or wrap would make the exhaust ports run hotter.
Pettit does cooling mods for the lead/trail sparkplug area through an access they drill between the two sparkplugs. I now have a sealant plug between those two areas. like a water jacket plug.
I know my engines were not high mileage under boost engines (25000miles max)--but none of mine had any markings like that. My engines were ran pretty hard due to multiple track sessions--even in 105F ambient weather. SWEAT
Cam even recommends to not wrap or ceramic coat your header ( oem or aftermarket). He told me that the rear rotary exhaust port has more trouble cooling and a coating or wrap would make the exhaust ports run hotter.
Pettit does cooling mods for the lead/trail sparkplug area through an access they drill between the two sparkplugs. I now have a sealant plug between those two areas. like a water jacket plug.