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Hi guys since the rx-8 forum is quite unfriendly i thougt id ask you guys.
im replacing my sa22 rallycar with a 2005 rx-8 192hp 5 speed manual.
Now ive done lots of early rotaries and and never had to change sideseals and so on.
so i guess my question is to get a low compression renesis up to high compression again how much do i need to replace. i do know that there is specifiactions but i want good high compression i dont just want to be within specs. But on the other hand im only racing the car so i dont need 10000 miles in the engine .
It seems that alot of people replace all the seals every time but is that really nessesary.
Best regards Rasmus Andersen Denmark.
Bonus question does anyone have anything to say about cryo treaded atkins seals?
There is no difference in Compression Ratio between the 4 port and 6 port high power Renesis.
The 4 port just had lower redline and thus Mazda cut some corners on engine internal parts to save cost.
To increase the redline to that of 6 port Renesis without sacrificing any of the reliability of a 6 port Renesis-
You should replace the 4 port stationary gears with the 6 port hardened stationary gears (N3H3-10-E0YC and N3H3-10-E1YC).
You should replace the rotors, counterweights, eccentric shaft with a matched set from a 6 port Renesis (since they are dynamically balanced) or if you trust a shop have your 4 port rotating assembly balanced.
All the 4 port rotating parts are the same as 6 port Renesis, just not factory dynamic balanced.
You should use the used 6 port bearings for rotor and stationary gear, if you replace them you should use the largest bearings available for each location.
You should use the 6 port rear and front housings for the late closing auxiliary ports if you want to make the 30hp from revving the motor from 7,500 to 9,000rpm.
You can use either the 4 port intermediate housing or the 6 port one. The 4 port primary ports close 5 degrees earlier than 6 port primary ports (obviously can be ported).
There is no difference in Compression Ratio between the 4 port and 6 port high power Renesis.
The 4 port just had lower redline and thus Mazda cut some corners on engine internal parts to save cost.
To increase the redline to that of 6 port Renesis without sacrificing any of the reliability of a 6 port Renesis-
You should replace the 4 port stationary gears with the 6 port hardened stationary gears (N3H3-10-E0YC and N3H3-10-E1YC).
You should replace the rotors, counterweights, eccentric shaft with a matched set from a 6 port Renesis (since they are dynamically balanced) or if you trust a shop have your 4 port rotating assembly balanced.
All the 4 port rotating parts are the same as 6 port Renesis, just not factory dynamic balanced.
You should use the used 6 port bearings for rotor and stationary gear, if you replace them you should use the largest bearings available for each location.
You should use the 6 port rear and front housings for the late closing auxiliary ports if you want to make the 30hp from revving the motor from 7,500 to 9,000rpm.
You can use either the 4 port intermediate housing or the 6 port one. The 4 port primary ports close 5 degrees earlier than 6 port primary ports (obviously can be ported).
Thanks all very good info but I'm keeping the 192 hp as it is and just raising the red line to 8500 rpm. The 192 should have enough torque with a little porting to do very well.
My questions is wether it's nessesary to replace all the site seals since I've never had that issue on earlier rotaries
Previously on engine rebuilds new apex seals has been enough
Nothing on the 4 port motor needs to be changed to run to 8,500rpm.
Changing out the stationary gears and rotating assembly for hardened and balanced 6 port parts will just make it more reliable at high rpm.
If you fill the (unmachined) aux port runners and port the 4 port runner a tad bigger and the port face for later closing the 4 port will have more peak power potential than 6 port Renesis.
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If you are allowed to mix and match engine series parts and/or modify parts you can come up with a cheap powerful engine.
If you want some ideas- let me know the racing class rules.
Thanks all very good info but I'm keeping the 192 hp as it is and just raising the red line to 8500 rpm. The 192 should have enough torque with a little porting to do very well.
My questions is wether it's nessesary to replace all the site seals since I've never had that issue on earlier rotaries
Previously on engine rebuilds new apex seals has been enough
i haven't had one apart yet, but the renesis side seals see exhaust gasses, so they wear faster. they also built these at the factory with precut seals, and you have to wonder if that wasn't consistent enough
I'm allowed to do whatever I want to the mechanical part of the engine I'm not allowed to change exhaust ore intake manifolds.
I've done a large street port (rally port) on my sa22 and it really works great I was thinking about maybe I can use the porting template for the renesis as well since I haven't found any info on porting 4 port renesis. Then I will get a reflash and build a new exhaust from manifold and out.
I really just want torque and good hard power from as much down low as possible. My current engine works really
Great with fc tranny and 5,13 rearend I'm always shifting in to
More power.
I'm not on that tight of a budget but keep in mind that everything is about 2,5 times more expensive for me to buy for our cars example the car it self cost about 20000 dollars and a housing 2000 dollars
I'm allowed to do whatever I want to the mechanical part of the engine I'm not allowed to change exhaust ore intake manifolds.
I've done a large street port (rally port) on my sa22 and it really works great I was thinking about maybe I can use the porting template for the renesis as well since I haven't found any info on porting 4 port renesis. Then I will get a reflash and build a new exhaust from manifold and out.
I really just want torque and good hard power from as much down low as possible. My current engine works really
Great with fc tranny and 5,13 rearend I'm always shifting in to
More power.
I'm not on that tight of a budget but keep in mind that everything is about 2,5 times more expensive for me to buy for our cars example the car it self cost about 20000 dollars and a housing 2000 dollars
Best regards Rasmus
Ok, so it sounds like-
you may use any 12A or 13B but keep that motors stock intake and exhaust manifold on it.
You may modify all engine internals.
Can you change engine internals from that of another series rotary?
Are you allowed to port your stock intake manifolds?
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On the 4 port Renesis you will find your porting templates will not work. The Renesis rotors have the side seals moved outward and a button head corner seal so they are ported for very early intake opening from stock.
You can use a 6 port porting template for the 4 port primary ports and for the opening edge of the 2ndary ports and make your own 2ndary closing line or just use the 6 port primary porting template on the 2ndary ports as well.
You will see the differences when you open the Renesis!
If you epoxy fill the unused/unmachined aux port runner above the 4 port 2ndary ports you can port them for later closing. Not sure if you have to fill above the primary ports to port for later closing timing.
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Later closing timing will help your high rpm power, but will hurt your low rpm power.
Porting for overlap will help power in low rpm and will help power in the high rpm if the rest of the intake manifold can be ported so intake manifold is not limit on flow/power.
Porting for overlap would be to bridge port the intake ports on the motor.
Max power on a ported stock intake manifold you might be achieved with a monster bridge or J-port.
It is a peripheral port that uses the stock intake manifold/runners basically.
You fill the stock ports for more low end power or leave them open for most top end power and make a huge bridge port that starts back in the water jacket of the side housings and you cut away the sides of the rotor housing to become the other side of the runner.
This is the port that Mazda used when Japanese Touring Car series banned peripheral porting in the early '70s.
It made the same power as peripheral porting, so they again allowed peripheral porting as long as Mazda sold the MFR housings to the public.
this is awsome thanks guys.
MY plan is actually a bit more down to earth at first. im doing rebuild and getting the compression up to speed i think i will change all the bearings as well just to be on the safe site. ive come to the conclusion that finishing races will get me more points than having to retire due to pushing the limits to far. then i plan to do som kind og port job but i really havent found any usefull info on porting this particular engine. so i guess i will order a template for the 6 port and work with that.
since you're going that route, you might as well get the high power spec bits. one other thing you might do is find a high power center iron, i think the intakes are the same, but the high power has more exhaust port timing.
the limit with the renesis is the exhaust port, so anything you can do here should help everything.
if you look at the renesis in detail, the exhaust port change means that they can give it a much larger intake port without having overlap than the previous engines. the port area also is much larger than say an FD engine, it is closer to the old peripheral port race engines.
the problem with the renesis is that while the exhaust ports are big, they do not flow very well, instead of an almost round straight port, they have two small, 180 degree bends. this is why the engine is insensitive to tuning, or different exhausts, its because the exhaust ports are already the limitation.
If you do new bearings there can be high spots from pressing the bearing in that will have to be worn down.
You can also flap the inside of the bearings with fine grit sandpaper and a die grinder to get larger and varied bearing clearance (more clearance at outsides needed to accommodate e-shaft flex/wobble) and help take out the high spots.
05-05-16, 10:54 AM
