olddragger

iTrader: (3)

great info RG-- sounds like Mazda put a lot of effort and thought into R&D for this engine. I understand why they didnt put real gauges in this car but why the heck did they mandate 5W20 for all temp zones I will never know. Well I do know but it still doesnt make sense to me.
Keep the info coming--any benefit in the rotors from heat plating or blueprinting the leading edges?
Olddragger

dillsrotary

good read, question though. Exactly what effect would direct injection produce compared to the current set up of the renesis?

rotarygod

Direct injection if implemented properly would mean better economy and emissions over the current engine and perhaps even some more power. I don't expect to see miracle power increases but everything helps.

A downside would be that due to very precise fuel metering, there is no aftermarket ecu out there right now that can control direct injection. You could not change anything until a flash was developed for it. In other words, no forced induction until after the ecu is figured out. Mazda has been working on DI for years. I suspect one day we'll see it appear on a production rotary as the engine isn't going away any time soon.

LionZoo

Too bad there isn't an easy way of changing out just the 6th gear ratio. All the other ratios are fine with me, but 6th is too short.

Lasse wankel

Very helpful info RG!! This info helps me investigate and improve the Renesis engine, so i can sell RX-8 engine kits and do some heavy porting on it.

/Lasse

Nubo

This is why I worry about the prospect of getting a remanufactured engine. Is it possible, or even likely, that some of this coating would be machined away in a remanufactured engine?

swoope

iTrader: (5)

nope that is the point of the recall....

beers

supergoat

I'm a fan of this thread.

rotarygod

Nope. They use all new seals.

Dookie_Rx-8

good read rg... this is what some of the 7 owners should read....

i hope i fail my compression test...haha

Raptor75

I think he may have meant the coating on the housing which would also be a concern of mine.

Kevin

supergoat

I would think that Mazda would have the housings re-coated if it was really an issue. Do you think they'd really send out remanufactured engines that had this coating machined off after going through the trouble and spending countless amounts of money on the recall in the first place?

Also, I remember reading that housings are typically not machined. They are either able to be re-used or they're junked. I may be wrong, but that sounds right.

8 Maniac

iTrader: (1)

RG, do you know what the beginning of time was like? when the world is going to end? Thanks for all the info, explains a lot to all of us. I've actually been wanting to find out more about the engine (rotaries in general) and this actually helped a lot.

rotarygod

Have you been to any of the local club meets? We now have a northside meet. I'm in Spring.

rotarygod

They don't recoat anything in a rebuild. They measure the wear on a used housing and if it is within spec, they still use it. That's it. The Nitride coating on the rotor housings is decently thick and most wear grooves are still within the thickness of the coatings. This is why some people say it is bad to resurface housings through lapping or grinding. Typically the process removes the coating completely. While this leaves a nice smooth housing, it also leaves it more prone to wear so it's a tradeoff. I keep planning to find out who can apply this coating to housings so you can resurface them and recoat them. I know who I can ask next month at Sevenstock so hopefully I can get an answer.

8 Maniac

iTrader: (1)

I havnt, I need to update my location, I moved for college so now I'm actually over in san antonio =( maybe I could make it to a meet when I go home for the weekend or something.

Chrissss

RG here is a firm that does recoating.

http://www.jhbperformance.com/

I have not used their service myself but I hear the product is supposed to be quite good.

Chris...

rotarygod

Without going into too much detail let's just say that I refuse to give them any of my engine parts until they prove themselves in a little more consistent and reliable manner.

Chrissss

Like I said, I wouldn't know since I haven't dealt with them...yet.

Of course they're a local firm so comments I have heard are favourable. Not having to deal long-distance & cross-border make life MUCH easier.

Have you had consistancy issues with their product? PM me if you don't want to post details.

Chris...

Charles R. Hill

iTrader: (7)

So, RG, it seems our conversations and speculations from 2 1/2 years ago (when I was pondering nitrous use) have proven true in that we both suspected that Mazda HAD to have made improvements over the old 13B when they released the Renesis. It was the conclusions you and I came to that empowered me to embark on the nitrous project. Thanks for the detailed info on WHY this engine is far more accomodating to the abuse I have subjected it to when compared to previous versions of the rotary engine. 11,000 rpm's, nitrous use during the fuel cut, and several episodes of knocking/detonation, and it still runs like a Swiss watch.

zoom44

this is general rotary tech not renesis specific- but two of the "problems" with rotaries hav ebeen low Torque and innefficiences related to the combustion chamber shape. digging through some things to find the geometry associated with sizing of rotaries reminded me i have been thinking how to change the various dimensions to overcome the issues.

first T. the T is "small" because the "length" of the "lever" creating that T is short. is there a way to increase the internal or external diameter of the rotors to inpart a greater force on the eshaft without detrimetnal effects in longevity or efficiency?

efficiency- shape of the combustion chamber is too long for really efficient combustion- flame front propagation etc. would widening (adding displacement)the rotors to create a more square chamber create a more efficient rotary or would the added displacement offset the gain? would widening but shortening to create a more square chamber of the same displacement work better?

just a couple of the thoughts racking my brain through the average day.

rotarygod

Torque is a function of displacement. The rotary has very little displacement so torque will always be low without added help. If we were to change the "stroke" of the engine but adjust other dimensions so the total displacement didn't change (narrow the rotor width), torque should not change in terms of overall peak but rather in terms of where it occurs in the powerband. The greater the stroke, the lower the torque peak. On a stroked piston motor, we tend to see everything go up but remember when they add stroke to those motors, they also add displacement. If they were to add stroke but decrease bore to keep the engine the same total size, peak torque would not change appreciably but the rpm it ocurred at would. A short stroke motor has a torque peak higher in the powerband.

As far as widening the rotors, we'd need to reduce the "stroke" of the motor to keep the displacement the same. That would be less efficient down low and would need higher rpms to get to it's best power. Narrowing the rotors would need increased stroke to keep displacement the same. It would be more efficient down low but not as high up top. When displacement remains constant, it is a balancing act to decide which combination will yield the best overall compromise for the engine's intended use. While a more square rotor face may be more beneficial from a fuel combusting standpoint (it may not though), the difference in stroke may offset this so may not be able to use it to any advantage.

zoom44

so lets increase the displacement by making the camber wider and therefore more square. or enough to make it exactly square. does the increase in displacement offset the gains? i cant find any information that this has been done and the results good or bad. maybe someone at 7stock will be able to answer. ill have to get the question translated to japanese probably.

rotarygod

I am not a fan of making the rotor any larger as it has several issues to overcome. The first of which is that we can not make our ports any larger to give us the needed airflow up high. They would be large enough to supply air for a lower powerband but if this mean that we weren't getting any more power out of it, no one would be happy with it. The other issue is that a larger chamber would mean a larger area for the flame front to travel and this would result in lower efficiency and worse emissions as a result.

My choice would be to use a 3 rotor that is smaller in every way but of the same total displacement as the current 2 rotor.

zoom44

i just remembered reading something recently suggesting the larger square rotor would not have the same flame front issues. wish i could find it now