Renesis and rx7 FD 13B Hybrid engine
 

Recently in North Borneo we had a 4AT rx8 blown. since i am the representative of the RX8 Club Malaysia in North Borneo, of course i tried to source out engines and options with the lowest price.

But i had a Problem, The Owner insist to put back his Bolt-on Greddy Turbo kit. Which according to many parties that, the turbo was the reason that cause the engine blow in hot climate in malaysia.

After a lot of searching, we found someone in japan who can supply a Hyibrid of 2 13B engine.

REASONS:
for this assembly is because it could provide a realiable 13B engine that is suitable and sustainble for a turbo.

ASSEMBLY:

Front Engine Housing (1)
Renesis 13B
+
Rotor and Rotor Housing (2)
RX7 FD 13BT rotor and housing with special Apex seal
+
Mid Engine Housing (3)
Renesis 13B
+
Rotor and Rotor Housing (4)
RX7 FD 13BT rotor and housing with special Apex seal
+
Rear Engine Housing (5)
Renesis 13B
+
Side Seals & O-Ring
Fix type without spring (not sure whast this)

UNCERTAINTY:
1. How they put this 2 engine together, since the gasket is not the same.
2. Side seals type and source.
3. how would the injectors fits.
4. They promise 1 bar boost, could this be possible on rx7 FD engine? and realiability on RX7?

THE COMPANY that offers to do this:
http://www.topfuel.info/

***I would really appriciate if anyone with answers and more info to post here***

UNCERTAINTY:
1. How they put this 2 engine together,

It seems impossible to me, the FD rotor housing has a peripheral exhaust port.
Atleast he won't be able to put the Greddy kit back on, the exhaust is in the wrong place!
....but they claim to do it, ask them. Why ask anyone else?

S

Cause this is where RX8 tech comes in. but thanks for the feedback though, its important cause we now know the exhaust port is on the rotor housing for FD engine.

By the way, just to input more info, we had a guy here had 2 engine blown after bolt on turbo, what he did was deepen the compression area on the rotor, he had no problem then til now.

I actually had this idea about a year ago. Using the fd rotor housings and the renny end plates. From what i understand the housings will match up. The point was to fix the exhaust ports. However i didnt plan on blocking off the renesis exhaust ports. It would run both renesis and fd exhaust ports and they would be unported or ported very little. The 6 intake ports from the renesis would be ported fairly heavily due the fact thet the renny ports are the only intake ports. I didnt figure the rotors out because fd rotors dont gel with the renny housings. I was hoping for some after market rotors. The exhaust manifold would be composed 5 pipes which obviously lead to a good size turbo. I would really like to see this vision running. I hope someone can find more info about it cuz it sounds kinda like my vision.

Red_Devil, thanks for your precious info.




mike1324, this really clearify most of the structure. Thanks a lot.

Use a 84-85 13B rotor housing, that will solve the soft seal issue, Pre 86 had their coolant seals in rotor housings like the 13B-MSP (renesis) engine.

I don't want to bring this back from the dead, but what keeps you from using rx7 9.0 compression rotors in a renesis .... you just need to rebalance the e-shaft and then you are good right? .... I know people use the lighter rx8 e-shaft in some rx7 rotors, they just need to rebalance it.

If you intend to keep the exhaust side ports you'll have to use Renesis rotors due to the required side seal setup.

Several companies can add the coolant seal grooves to later 13B rotor housings. Guru Motorsports down under is one that comes to mind.




.

Citation needed.

:dunno:

Sorry, I don't school n00bs in Renesis 101 basic facts

try searching Renesis side seals, there's a reason they were changed from the 13B side seals

He's not asking for schooling , he's asking where you got your information (in case you just pulled it out of your ass). Big difference.

Help us out, man. ;)

The RX-8 rotor can be modified to accept the 13B 2mm apex seal and by using the RX-8 rotor I was referring to the entire seal configuration on the sides. The compression is only an issue for very high boost FI applications.

No I'm not trying to be an ass, but if you want a citation go to Wiki. Otherwise the seal configuration relative to the Renesis rotor and side exhaust ports is very basic info. I'm not going to respond to prove it requests over such basic info.

it's an issue for every boosted rotary application. take it from someone with 8.5:1 rotors, it makes a huge difference in reliability. there's a much bigger margin for error in terms of fuel quality or human error.

I can run almost 17psi on a good sized turbo (T04R) running the same ignition advance that a typical Renesis is running at 7psi. It's not that more ignition advance is always the best thing, but it shows how much more forgiving the low compression rotors are. And it doesn't affect spool much, proper turbo and manifold choices are the key to that besides tuning.

That's on normal 93 octane, no methanol injection, preturbo EGT's over 1700 degrees yet no detonation problems.

if you are running highish boost, first thing to do is lower compression .. I dont care if you have a push rod, a four banger, or a rotary ... once people figure out how to do that, renesis engines over 400 hp wont be a novelty anymore


TEAMRX8, thanks for the response nonetheless, I am still noob at the more specific things


Also, could a temporary solution be to make a late closing intake port so that it closes somewhat into the compression stroke resulting in a lower compression ratio be a valid idea?

It's an issue, but one that can and has been addressed through setup to some degree. It ultimately depends on how much you're going to push the boost/engine output. Beyond a certain HP limit is uncharted territory for the Renesis. That doesn't mean it can't be done, it's just uncharted territory relative to the history of the 13B.

The below was taken from two RotaryGod posts on the subject.

The rotors themselves are the same physical size. There are some diferences with the seals though. The Renesis rotors have a cutoff seal in between the side seals and the oil control rings that the 13B's do not have. The shape and size of the seals is also different between rotors. Due to this fact the RX-8 rotor can be used in an RX-7 but not the other way around. You'll just have to trust me on that one. The casting thickness of the RX-8 rotors is also thinner than the 13B which makes them less strong but lighter. I'm not sure where you can get any dimensional drawings. I'll start digging.


While they will physically fit, the RX-7 rotors do not have the cutoff seal that the Renesis rotors do. As I learned from Ray's motor, this seal is in place to protect the oil seals from exposure to direct heat from the exhaust. Without these seals, your oil control rings will fail prematurely. Who knows how long that may be but these seals were added for a very good reason. I personally would not use a 13B rotor in a Renesis for this reason.

Uh yeah, let's just cut out the baloney and go to the source

http://www.rotarydevelopment.net/Rot...790_Rotary.pdf


.

Hey, all I asked was why it will not work. :dunno:
I really did just want a reason why it doesn't work. :yesnod:

great article !

OK, I have checked with my builder and was given the OK to let the cat from the bag....

I AM running low compression RX7 rotors in my Renesis.
Rotary god is also correct that this cannot be done without the RX8 gas control rings.
The rings slots were machined into the FD rotors.

Running the 12 PSI Pettit pulley, now results in 10 PSI boost, the engine is smooth and pulls HARD.
I have not dyno'd yet, until I can get tuned properly, as I am still running too rich.


Sorry I could not tell before, but it was/is a prototype.

Yes, Cam.
Why would you say not Cam?

:icon5:

Was making a guess based on previous conversations between myself and him. Either way, pretty cool. Can you give any further details - how many miles or how long ago was the engine built? Any plans to up the boost?

Very interesting . So you now get lower boost on the same pulley ?

Awesome. :mdrmed:

Lower boost; from more chamber volume is a guess.
MAF numbers look good though, and not really pushing it yet.

One more thing, the engine runs much cooler, I thought my fans were broken when I first started driving it.
I can drive it hard, stop, idle a minute, shut down and the fans just run a second and turn off, they used to run for a while.
I barely get over the thermostat temp.

/\ similar maf numbers or is it higher ?

would be very interested to see the effect on a turbo engine .....