Check out this sasklopper's ride: https://www.rx8club.com/vbgarage.php?do=view&id=29886

What's up with the rotors?

 

Looks like he modified FD rotors.

 

They are. Carlos Lopez does that and takes it to the extreme using older 2nd gen RX-7 rotors. The chamfers that are mentioned are on the stock Renesis rotors. These are the angle cuts on the edges of the rotors. We call them scallops. This is just adding the same basic thing to rotors that don't already have them.

 

Sas bought an SFR single turbo system from us.I didnt know he hade all of this done to his motor though.

 

so this is possible, to use 5th gen FD rotors? What about other 13b rotors if you scallop them? Any modifications need to be done to the housings?

 

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.

 

I'd rather have an oil control seal fail on me than a rotor. In my humble and limited experience with the 13B-MSP engine I feel it's best to leave this engine unboosted with Renesis rotors. If you want power then replace the engine with a 13B-RE or alternatively take the route I took.

We have a number of normally aspirated race cars using Renesis basics with 13B rotors in Cape Town. All of these are raced hard and most have been running sweetly for a number of years.

It's impossible to make any side and aftermarket seals work successfully on the boosted Renesis engine using standard rotors. I wish I've kept the old rotors to illustrate my point. Even at 0.5 bar boost the rotors started denting due to their inability to take the increased pressure. If you supercharge the same will apply.

This car has now ran for a good few thousand kilometres under varying driving conditions with no problems. If an oil control seal fails I'll find a way to protect them.

Meanwhile it's a pleasure boosting this car to 1.1 bar and showing some of the big guns what acceleration really is in 4th, 5th and 6th gear.

If it breaks I'll fix it. However I'm positive any failure will not be as catastrophic or expensive as losing a rotor, seal or housing!

......that's what modifying is all about. Experimenting!

 

Woah. I want to hear more about this. Subscribing.

 

Wow I didn't even think this was possible.

 

Tim,

I never mentioned this to you but the second MAF housing you sent me is the incorrect one as well. Please look at the photographs I sent you and make sure your machinist does not make this mistake AGAIN. I'll return this one to you. Meanwhile I'm still not happy with the modification I made to get the old one working. It is a quick fix and not how we do things. Please let me know.

Thanx

Sas

 

Hey Sas, hope you did not mind me linking up your virtual garage, but I had to see what the guys would say.

I left you a note on the bottom of your garage page - nice ride indeed

 

I am going to just disagree with this statement as Scott and many others have already proven this to be wrong. If you are killing seals at half a bar, you need to tune it better. I know the limit isn't as high as the 13B rotors but to say that they'll die at half a bar is false.

 

saskloppers,

Was it really expensive to do this?

 

Get ahold of some RX-7 rotors and counterweights, and rebuild the engine using them. That's basically it. Scalloping the rotors is another matter altogether. I'm still not going to try it until I see an engine cross 50,000 miles at the very least with them and I think that's being overly generous.

 

RG, if possible, could you please expound a bit on "scalloping" rotors, for those of us that are ignorant...

Thanks

 

Hmm, just to clarify, if "RX-7 5th Gen" implies the Series 5 RX-7 then these would be FC rotors not FD (as RG stated earlier).

Thanks!
Edgardo

 

The other problem with non Renesis rotors in a Renesis would be side seal location and how they relate to the ports. You will experience very accelerated wear.

 

If anything this car was tuned properly.

I challenge anyone to run this engine at half bar under the conditions we did without damaging anything. We put it on the track at 43 degrees C (had to as we entered the race without knowing what the weather would do. At sea level, running continuously at half bar at between 7 and 9 k under 113 kPa load dented the rotors.

The car did 64 laps (around 200 kilometers) at our local race track that day no problems. I was lapping between 4 and 6 seconds a lap faster than a Noble, at almost 5 times the price of the RX-8.

I broke the motor on the dyno on the Monday morning after racing. Never once did I blame the turbo, the design of the rotors, the management, the weather conditions or anything other than myself. What I said here stays. Boost at 0.5 bar continuously using Renesis rotors will cause some damage to the rotors over a long period.

The seals I broke, mapping. I did not keep an eye on the temperature gauge and the car overheated. The radiator cap was of insufficient pressure and it dumped the coolant without me noticing. When I saw what happened it was too late.

Needless to say I now use a higher pressure radiator cap.

 

Not at all. I've upped some new pics are we're working on graphics for our next race meeting. These are done in vinyl and I wash it off using a high pressure cleaner when I'm done. No painting so nothing's permanent.

 

Frankly it's no problem for me. I only occasionally use the car as it's mainly a toy for me to use on track days and when we do some drifting, etc. I have 13 other cars (yes, it's stupid, I know) and my daily ride is a new S500 Mercedes Benz. So the fact that it might not outlast the rest of my "fleet" does not bother me one bit. On the other hand, it will be most important to someone using their RX-8 for daily commuting. I doubt if I'd do more than 4000 kilometers per year, so if it lasts for 20000 kilometers before the oil control seals or side seals needs replacing I've had a lot of fun for a long time.

 

I don't want to sound arrogant but my idea of expensive and yours might differ. However, no, it was not at all expensive, but very time consuming, doing everything properly. I think we've stripped and assembled the engine a total of seven times, making sure there'll be no problems before we started it. Oh, and it took a long time to get the rotors back from coating. We could not get them done in South Africa so I had them shipped to the USA to have it done.

 

On the Renesis rotors there are chamfers on the sides which allows for the side ports to remain open fractionally longer. We've machined these into the 5th gen rotors to get the same effect. I'm doing another two sets of rotors at the moment also with Hurley seals and will post photographs when these are available.

 

could anyone please advise me if it is possible to disconnect the APV and leave it in open position?

The AFR goes a bit lean the moment the APV opens at 6800RPM and I resolve this by adding a lot of fuel at that point, but there's a sort of an hesitation when this happens and the engine does not run as smoothly at that point as I would like it to run.

My thoughts are that by leaving this valve open I can remap the whole fuel map to the required AFR, without the hesitation or the need to add so much fuel at that specific point. I will however have to do the mod in such a way that the ECU still thinks it is in control of the APV.

Anyone has some thought on this?

 

https://www.rx8club.com/series-i-major-horsepower-upgrades-93/cracked-front-housing-119714/

not so good..

beers

 

Any updates? I am very interested to hear how this project is coming!