RX8 internal parts
Hello out there!
First time here. As a long time Mazda technician, I have some questions I hope some of you can shed some light on. It revolves around the new internals of the RX8. I have all the internal parts sitting on my bench, and am missing some of the details that others have been talking about. I have weighed the rotors, at 4.235 kg, they are not terribly light, compared to the race 20b ones. The counter weights are indeed thinner, but actual weights are similar. What is very curious are the stationary gears, now i might be missing something, but I cannot fiqure out what is different. They are, to my eyes, identical to the old 13b ones found in the gsl-se. I have a set of original Mazda factory race gears, and other that the race modifications done to the rear gear, can spot no difference. So why are the renesis gears given a different part number? These gears also look to not have been hardened nor grooved and installed with a multi window bearing like the twin turbo ones, anyone know why? Also, what is so different about the e- shaft? Dimensions look to be the same as the past ones. Anyways, any light which can be shed would be appreciated. Thanks, Mark ( I will save talking about the rotors for later) |
Rotor weight reduction compared to the 3rd gen RX7 was stated by MC as 11%, or about 300g. The ribs inside the rotor are thinner.
The flywheel is 20% lighter. The stationary gears are cut slightly differntly for noise reduction. From memory the sides of the teeth (the meshing area) on the Renesis are slightly rounder than the 3rd gen. Or flatter, it is 2 years since I compared them. No idea about the bearing. E-shaft dimensions are the same, it is supposed to be stronger and lighter (more holes in rotor bearing area). Hope this helps. |
RX8 internal parts
Hi,
As to the gears, the stationary gear tooth profile is identical to all previous ones. The only machined difference between the two, are the renesis looks to have a deburring procedure at the very tip of the gear tooth. Has anyone run renesis rotors on old style gears/ shaft? Why has Mazda decided not to groove either front or rear gears and not installed a multi window main bearings? Does this mean that they have eliminated shaft flex at high rpm? I kind of doubt it. A good example is the race three rotor, not the failure prone cosmo version , which still uses grooved window bearings, but has lighter rotors and rotor bearing journals which are 1.00 mm larger on the od. Also as a side note are the rotor gears now hardened? By appearance, it looks grey where all the others are shiney. Is this a coating? Thanks, Mark |
Mark,
The bigger question, since you have the engine apart, is just how similar the parts you see before you are similar to the performance versions of the same. This testimony will give the rest of us a much-needed break from the cynical naysayers who have told us for months that the Renesis is weaker than previous versions of the rotary. I have disagreed but that was only on a philosophical and historical basis rather than engineering or visual inspection. If you can give us your interpretaion on the comaprison of the seals, rotors, shaft, housing, and etcetera, that would be a great help as to the ultimate performance levels the Renesis is capable of. Thanks in advance. Charles |
Pics would be usefull also.
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Oops, I forgot we are a visually-driven culture. Sorry.
Charles |
RX8 internal parts
Hi,
I have heard alot about the increased strength of the eccentric shaft, I'll have to say its not, as dimensionally it is identical, material is also the same. Mazda has only increased rpm limit to 9000. At this level things are just starting to get interesting. Shaft flex will always be the limiting factor. That is why the factory came up with All the race proven procedures to help the engines reach their power / rpm limits reliably. If you think along these lines, than the twin turbo was indeed capable of more power. As to the renesis being weaker, I think its just a different animal. Its purpose is not ultimate power. Because of the side port intake and exhaust, it will never exceed the power levels obtained by the peripheral design. But I really like the rotor design, and will be using them in several race engines soon. First, I will need to have a complete grasp of what Mazda has done with the renesis. Again, anyone with some ideas, lets hear em! Thanks |
Originally Posted by MarkJ
Because of the side port intake and exhaust, it will never exceed the power levels obtained by the peripheral design.
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The restrictive nature of the port design limits potential horse power levels. If you compare
known horse power levels with existing four port engines, normally aspirated of course, with those of peripheral port race engines. There is no comparision. The renesis engine was designed to improve fuel economy, reduce emissions and create an acceptable level of power. They did this by reduceing the intake charge dilution that occurs with a peripheral exhaust port. Unless someone out there is working on getting a 13b to rev into gods country, a peripheral port design will make more power than a side port. Now that we have access to higher compresion rotors a peripheral port will now see a significant increase in power. |
yes, it's just completely an issue of flow and efficiency, p-ports will always make more power than side ports at high rpm levels.
i'm still wondering what would happen with a perhipheral intake port and side exhaust ports, might be really neat. |
I was thinking small bridge with side exhaust. It may create a slightly better behaved bridge port. However, having spoken to one wiser than myself, it was pointed out that although this may work it is limited by the lack of overlap (yes the same evil overlap that your getting rid of by using side-port in the first place.)
since the overlap allows you the scavenging effect. This is probably why there is very little horsepower to be gained through exhaust tuning on a renesis. |
Mark J can you confirm that the Renn shaft is dimensonally the same as previous 13b shafts? I heard they the oil groove on the front main bearing journal is moved slightly fore or aft (cant remember) compared to previous shafts.
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What would be the benefit of moving the oil groove?
I sort of understand wakeech's idea of utilizing a p-port while keeping the side exhaust. Using an intake peripheral port, you can have the maximum inlet flow area without compromising the corner seals. Keeping the side exhaust port, and not having to resort to a p-port, the engine won't have to scavenge some of the waste back into the intake stroke. It's all clean and simple. And on the plus side, I am sure you can safely put on the boost. But, what about idle and low speed driveability? Is a lopey idle an unchangable characteristic of having a p-ported rotary? |
If someone wants to foot the bill, I can have an RX8 rotor housing
modified with a peripheral intake port that uses the same port timing as the comp. housings. Cost, 700$CDN not including the housing. Intersting to see the results, anyone game? |
Hello,
Long time since ive posted but been very busy, The stat gears on the rx8 motor may look the same but there is one thing different and part numbers and other items help to prove this... That is they are directional to the rotors, meaning you have to use the specific front rotor for the front stat gear and the rear for the rear, hence this is the slight burring on the tips of the teeth on the rotor gears and stat gears. think of it like this you cant grab a front rotor and stick it on the rear because the rotor edge cutouts and groove for the exhaust port would be on the wrong side... Its always better to have photos With the crank well it is lighter as we have weighed it and it has more meat taken out of the rotor bearing area, also the journal down the shaft is bigger hence the front bolt is now bigger and like with the old shaft were you would have to get the bearing surfaces clearanced to suit racing, the rx8 shaft already has great clearances to suit and mazda offer different sizes of rotor bearing clearances. And you cant compare renesis shaft and bearing clearances to MFR 13g engines especially crank flex we have got 4 of them here and 2 of them MFR specials and beleive me put them on some v blocks and a dial gauge and dont be suprised with the amount of throw out it can be scary, thats why thay run bigger clearance in the 13G especially the centre bearing, but the drag guys over seas have fixed this by tighting the front bolt to 300lbs fuuny but true.. Thanks Rxturbo |
Hey, hows it going rxturbo? How are your projects coming along? MarkJ is doing some similar things to you:peripheral with renesis and the 'right' seal material.
Have you found a solution to the side seal clearance thing? Nice to see you on here. |
hello again
I know its been a long time Well if you remember my old post I have already told everyone about the success of the PP intake and exhaust ports with stock internals rx8.. We have fixed the side seal problem and are now offering the modifcation to everyone along with the other great things we do..I dont really want to say how we have done it yet as it would not be fair to the owners of some of the race motors down here that we have had the mods done.. But the last motor we did was about $10,000 AUD just for the engine alone.. But we now offer all the mods as we have finished the R&D and are ready to have some fun!!!!!!!! See you around, Iam going to try stay around this time |
RXturbo, thanks for the message. The difference of the stationary gears still puzzles me,
I have measured both gears on a co-ordinate table, and have not seen differences in tooth profile. If this directionality is correct, I will need to make a center gear to fit the three rotor. The front gear looks to have the material to accomlish this. Frankly, I am getting tired of throwing time and money down the drain. Have you modified a front gear to fit the center housing yet? Also, how have the gears stood up? I will assume that you are grooving the gears and relieving the inside rear of the rear stationary gear. Anyways, thanks again! |
Mark,
We have not done any centre plate mods as yet but it might be something that we will try on our shortened 20B engines which a ser6 centre plate instead of the big 20B one this also help that crank flex I was mentioning, With the stat gears we do all the race prep stuff, I dont what gears are offered in USA but the gears we get here are already grooved with ser6 style bearing in them, but as Ive seen there has been a lot of difference between the two countries with a lot of motors including ser 6 and 5, especially 6 port efi motors which you guys had in the GSL SE rx7 gen 1.... But again photos will show it better. Thanks |
Hi ,
Rx8 stationary gears here are not grooved, front nor rear, have the small tang for location of the bearing and do not use the multi window bearing either. Almost identical to the early 13b stationary gears, with the exception of the increased size of the front thrust bearings. Not at all like the twin turbo RX7. I can send pitures if required. Are you using the short crank three rotor with success? Isnt that with the welded stationary gear? No issues with the set up? How many hours ? How are you getting oil to the bearing? Also as to the side seal question, any further info on longer seals? |
Hello again,
Looks like I might have a source for side seals. I will need to have a large number made in order to offset tooling costs. So far this looks to be the best way to go. I had contemplated machining the rotors for a larger corner seal, one way to eliminate the clearance Mazda designed for the Renesis, but have never liked to machine rotors. For one, it is extremely difficult to accurately set up the rotor. From the factory is usually best, but I have seen some bad new rotors. The Renesis rotors are machined the best to date. So I'd prefer to leave the rotor alone. So does anyone need some longer side seals? |
What if I wanted to machine the RENESIS rotor to drop the compression ratio? I want to be able to support a substantial amount of boost using pump gas.
What are the advantages/disadvantages of a longer side seal? |
Hi Shellys man, Renesis rotors do not have significant enough material in the recess to
drop cr enough for major boost. Longer side seals are intended to eliminate the excessive clearance found in Renesis rotors so they can be used in engines with peripheral exhaust ports. |
MarkJ, are you implying we are stuck with the 10:1 CR? I'm probably sure I can get away with 12+ psi with the stock rotors.
What are the effects of a longer side seal with a side-exhaust port? |
The side seal clearance on the RX8 looks to have been done by Mazda on purpose.
As the rotor crosses the exhaust port the exhaust gas would be trapped between the outer oil control ring and the side seal corner seal area. In the old days practically zero side seal to corner seal clearance was the hot set up. When Mazda adopted the side exhaust they had to prevent this blowby. Mazda had added a third oil ring to prevent the gases from getting into the crankcase, and shortened the side seal to purge this gas. But this is why you hear complaints of oil in the intake and hard starting/flooding problems. |
Mark,
I hope you have success with the longer side seals, its an expensive way to do it but, We dont do it that way and no before you ask Iam still not telling anyone unless they get us to do it and they pay for it... Its just not fair on us to give away that much info for free so everyone can just copy it.. Sounds bad, but you would be the same if your job depended on R & D and then selling the product. But soon everyone will get wind of it later when customers start talking away Thanks |
Thats ok rxturbo, as I have a pretty good idea of what you have done, and I would prefer not to machine the rotors. The level of precision in machining from the factory on the Renesis is quite astounding, many times better than was available in the past. From the extremely tight fit of the corner seals , to the highly accurate location of the groove they are fitted to. I'm also sure the renesis corner seals will produce more power. I have also recently learned that the factory engine builders in Japan have access to longer side seals,
and am trying to acquire these as well as the manufacured ones. Again, thanks for the info, you have helped even though you wouldn't reveal your secret. |
Hello Mark,
We have the right tooling for the job now and its spot on, but it has involved cutting up rotors to see how deep they are and were we can take them to. If you can get longer side seals great, we had worked with Racing beat and Mazdaspeed as we have know them since the beginning of our company, now on its 21st year, to see if we could get longer seals but only getting down to about 8 thou side seal to corner seal gap, which is not good enough, leading to loss of HP and hard starting, but now with the mod we have it spot on....But as I have mentioned in the past threads is that you cant run RX8 apex seals with a bridge port as it falls in the bridge so with our mods we can run the larger bridge port and normal size seals and good clearances all round and thats how we have found our HP and improved mid range torque.. With your setup which we have done down here ie 13B PP running rx8 rotors is you will find a second power surge at around 10,000 to 10,500 rpm depending on your manifolds, I beleive with the right length manifold ie about 2 to 3" to the stacks and A long exhaust ie collecting around the diff area or just after you should get a peak HP at around 10,500 to 11,000 rpm so every clearance is going to be very important, It would be good to see how you go.. Please keep in touch with the longer seals, very interested in helping you purchasing them in some way.. Thanks Wayne |
Wayne, out of curiosity, are you using hole saw housings or Mazda factory peripheral
housings? Factory housing horsepower is up around 360+. Manufactured ones not even close. As to the longer side seals, funny how Mazdaspeed is aware of the need but has no time frame for a solution. As I have heard, the seals are longer when maufactured and are cut down to one of four sizes. This rings true if you inspect the longest seal Mazda offers and one end has distinct hand filing marks. You would think, out of anyone, Mazda would have the best access to acquiring these!. (Maybe they do, and are not saying!) The aerospace company I have approached is still trying to come up with a cost estimate. One curious thing though, is that they can only manufacture the seal cross section in a ring, which will have to be cut up to fit. Not a problem for any competent engine builder. With that being said, I'm worried that if I commit to manufacture these then Mazda turns around and introduces their longer side seals, and I'm stuck with a bucket full. Anyways, I will let you know what happens. Thanks again, Mark |
Originally Posted by MarkJ
Wayne,
With that being said, I'm worried that if I commit to manufacture these then Mazda turns around and introduces their longer side seals, and I'm stuck with a bucket full. Anyways, I will let you know what happens. Thanks again, Mark You need to find a cost asp. BTW. We're getting 320 to 350hp at the rear wheels with custom made PP housings. |
that's fucking sick. way to go!!
what port shapes have you experimented with?? (just a curious non-competitor :)) |
Crisspeed, your getting 350 at the WHEELS! Is this all motor? If it is, at what rpm?
If you dont mind, send me a picture of these housings. |
Originally Posted by MarkJ
Hello out there!
First time here. As a long time Mazda technician, I have some questions I hope some of you can shed some light on. It revolves around the new internals of the RX8. I have all the internal parts sitting on my bench, and am missing some of the details that others have been talking about. I have weighed the rotors, at 4.235 kg, they are not terribly light, compared to the race 20b ones. The counter weights are indeed thinner, but actual weights are similar. What is very curious are the stationary gears, now i might be missing something, but I cannot fiqure out what is different. They are, to my eyes, identical to the old 13b ones found in the gsl-se. I have a set of original Mazda factory race gears, and other that the race modifications done to the rear gear, can spot no difference. So why are the renesis gears given a different part number? These gears also look to not have been hardened nor grooved and installed with a multi window bearing like the twin turbo ones, anyone know why? Also, what is so different about the e- shaft? Dimensions look to be the same as the past ones. Anyways, any light which can be shed would be appreciated. Thanks, Mark ( I will save talking about the rotors for later) I'm gonna have to call bs on this, I saw a renny stat gear at racing beat last weekend, the gears are definatly groved with multi window bearings and look to be factory screw locked. |
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So, whats up with this picture then? :confused:
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Figured out whats going on, Mazda sent me stationary gears for an automatic! :eek: Had to swap out the hard drive on my computer, to switch
over to the Mazda Electronic Parts catalog, (which I borrowed from the dealership) and indeed there are several different gears available. From the picture in the catalog, the gears look to be indentical to the twin turbo RX. Which is great , as I can use them instead of the ultra expensive Comp. gears. Thanks for pointing this out. Will know more when they arrive. |
Seems to be two alternates to stationary gear selection, an A marked one and
a B marked one. Might have to buy the engine criteria manual to figure this out. Does anyone have a copy?, or know about the differences in these gears? Its also funny how both engines in the same car can be so entirely different. |
Hello Mark,
In Aussie the A normally means it superseeds an earier part number, so as an example if you got a part and it is the same as a part from a earier motor then they scub the earier part number and then super seed it to the new part number on the new part and then charge you at higher price then before even though it would of been cheaper before, and still the same part.. Its a bit confusing The B I would have to find out!!!! If you want I will take some photos of the RX8 stuff we have here, as Ive got a motor nearly ready to build.. One of our special 13B B/port with rx8 internals for a street car, should be great.. As you might know we have auot and manual cranks and weights and different size rotor bearing on offer here from Mazda.. Till next Time keep in touch with the seals, Oh and if you wanted Ceramic Seals as well in either 2mm or 3mm twin spring 1 or 2 piece just give me a bell.. Thanks Wayne |
Finally got a firm estimate on manufacturing longer side seals. Much to my dismay,
the manufacturer wants 60 - 80 USD$ per seal for a run of a 100! :eek: End result is over 10K CDN$, needless to say I won't be following that route! Anyone have any ideas? |
What needs to be done to make these longer side seals fit?
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What do you mean, need to be done? These seals would be needed to eliminate the excessive clearance found with the factory side seals, when you use the
rotating assembly in a non side port exhaust engine. |
I meant something along the lines of doing some machine work.
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I was trying to find a longer seal that fits without modifying the rotor at all.
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Hello Mark,
If you are still keeping up with the forums here, then here is an update with the side seals, I would replied sooner but Ive had to get a new computer, We had managed to get the side seal clearance to a good 2~3 thou between the side seal and corner seal, but as you might of noticed the clearance changes when you push the side seal in on the rotor, this is beacuse they are tapered and when you push it down the top edge of the the seal gets tighter against the corner seal, sooner or later the corner seal is stuck down because the ends of the side seal get damaged, once this happens the rotor scuffs against the side plate damaging the corner seals even more. All of the tests done including making the gaps bigger to about 8 thou still has the same sort of effects, leading me to suspect the conventional bridge porting design with the reneisis rotors, As you might of noticed the side seals now sit up higher on the corner seals than earlier rotors have before. We are still going to R and D the idea but are going to go back to std style ports. All I know is that there would be no problem with running the rotors in a PP engine as there is no interferance problems Thanks Wayne |
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