Hi guys,



I'm in the planning phase of a Prepared-class autocross car that will see zero street use. Because of the class rules, the most effective motor will end up being a 13B PP. I've never built a PP motor before and have only built a couple of stock side port motors. The car has to weigh 1,962lbs with this motor. Comparable cars in class weigh 2100lbs and make about 250hp to the wheels.



My thoughts so far are as follows:



New racing beat peripheral housings

New stock Mazda intermediate and end housings (with ports filled)

RB lightened and side-clearanced rotors

New stock RX-8 E-shaft

5.5" clutch and flywheel with the entire rotating assembly balanced

RB machined and heat treated stat gears

Custom slide throttles

MoTeC or other aftermarket EFI

Not planning on going dry-sump since autocross doesn't have many sustained cornering events.



This motor will normally be operated from 6,000-9,500 RPM with an occasional trip to 10,000 as dictated by course design.





* What apex seals and springs should be used? I've heard everything from using Rotary Aviation seals to stock Mazda seals to RB Carbons to Ianetti ceramics.

* What intake runner length should be used? What kind of torque output can I expect?

* I have to meet a sound limit of 100 dBA at 75'. How many and what type mufflers will I likely have to run?

* Are there any particular things different about assembling one of these motors versus a stock motor?

* Any particular oil system mods that need to be done?



hoping some of you experienced folks can help me out. Thanks very much,



John V

dont bother waisting the money on the RB gears, just use the rx8 gears they are hardend and multi window and clearanced from mazda. as far as apex seals i have had great luck with 2mm NRS ceramic seals or the ceramic seals from mazda motorsports wich are Einettis or how ever you spell his name. i sugest if using the mazda motorsports ceramics to get the NRS spring kit though as they are more durable and wont ware the bottom side of the seal near as bad.



also with your induction system, read the rule book very closly on that because you may be forced to a limited size ie 42mm or something. and also read and make sure your allowed to use aftermarket rotor housings ie the machined and built RB housings and not the MFR housings. I had read a stupid rule someplace in a SCCA GCR about the housings at one time and dont know if that rule will apply to you or if it was even lifted since then.



a very well prepped 13bPP can make well over 350hp and have a bunch of rpm so this is why i question the rule with your competion being 2100# and 250hp.



randy

also about your 100db noise restriction, we have be under 103db with the EP car owerselves and what we do is run 2 inline mufflers and angle the tip slighly down and to the right facing away from the sound test equipment that all tracks have on drivers left.

Thanks for the tips, especially with regard to the RX-8 stat gears. As for the housings, the RB housings are legal but the MFR ones are not.



I do not have an inlet restrictor requirement under my rule set. The rules regulate vehicle weight by limiting displacement. A side port intake rotary is listed as 2616cc and the factor is 0.7 so min weight is 1831, but gets bumped to 1900 as that is the class minimum. For a peripheral port motor it's 0.75 * 2616 = 1962 lbs.



John

Even FC stat gears are good to 11,000 rpm. You can use the production oiling system with an FD oil pressure regulator, you need to run a baffle plate in the oil pan though to de-air the oil and maintain oil pressure. I have been running stock steel seals, they make power up to 10,200. The carbon seals are the most cost effective. I think you will find that on the track you are going to want your shift rpm to not drop you below 7500 rpm. I always got my fastest track times running the car above 7500 to 10,000. You will have a hard time making power and keeping it quiet. My car with 2 mufflers was 116 db at the starting line at 2000 rpm,, putting the baffles back in the muffler killed 30 rwhp. Realistic real hp for a 2 rotor p-port in a track legal configuration built with non exotic parts is probably 200-225 rwhp max. Keep in mind even the mazdaspeed prepared 13b p-ports were 300-310ps FLYWHEEL with no accessories driven and open header. Chassis dyno numbers are so damned random, you can't really go by whats out there for numbers as real world comparisons as I know on my own dyno I could have made more power and more impressive dyno sheet just by changing the rear wheels.

Long intake runner works better for a corked up exhaust, Short runner for uncorked. If your noise is an issue I would actually consider running a renesis motor, sadly, corked up they will make more power than a p-port.

Hm. That's pretty different from some of the experts I've talked to on the subject. None of them have said the stock seals will track well past 8500 RPM, and none of them have said the power will drop that severely when properly muffled. I'm not expecting it to be quiet - 100dBA is not quiet.



Was hoping Mr. Hanover would weigh in on this topic, I assume his interest in aviation has had him building at least one peripheral intake motor.

Hmm, I dunno what these experts are experts on then, mazda wrote enough papers on Pport exhaust results , it should be common knowledge. I tested it on my dyno to see what mufflers and backpressure does, and mazda is right, it just kills power, fast and hard... If it werent so, you still see alot more rotaries raceing, not being able to be competitive and quiet is what kicked rotary racing in the groin.

The stock seals are good balance between price and life, the carbon are not bad, but they take no abuse. I don't see a torque drop off with the stock seals till 10,000 rpm, its also about how you clearance them to. Re amemiya uses the stock seals in his 20 b pport in super gt, he doesn't rev to 10000, but it does over 9k. If you have a grand spare for seals, by all means go ceramic... But steel seals do work, I have over 4 years of track time on mine, and street driven miles, its never been apart.

The two guys I've talked to so far are Craig Nagler and Daryl Drummond... I think these guys know their stuff. https://www.nopistons.com/forums/pub...IR#>/dunno.gif

maxt, we are getting 202 to 205whp on a mustang MD1100 on a 6 port street port motor threw 2 mufflers and on an engine dyno with a single muffler and one of my headers i saw 245 bhp on a street port motor. the 245bhp motor was the only steal seal motor.



on the PP motor again i have seen over 350bhp threw mufflers on a 2 rotor PP motor. all 1 piece ceramic seal motors. there has been alot of minor changes in induction and header design and ports since mazda casted the FMR housings.



on the gear front i break s5 t2 gears easy. specialy at high rpm and also had major bearing failure. but since going to the rx8 stuff thoughs problems have lessend. also no longer take oil from the front cover, that is compleatly blocked off and now just take it out the side of the iron and plug the feed holes to the front cover and over to the OMP.



personaly to me for if nothing else piece of mind ceramic seals are a cheap insurance policy for the investment of a very high strung motor.

That doesn't mean anything, like I said before about dyno's the numbers are not neccesarily true numbers... They are comparison tools to themselves, not each other.. I could make my p-port read 300 rwhp on mine, does that make me think 2 rotor p-ports make 300wheel hp? no... because I know they don't, when Mazda uses calibrated instruments for R&D worth 30 times what we use and says they are 200 ish hp engines at the wheel, I will defer to mazda for the true number..

There is piles and piles of info on this stuff in the mazda papers and people continually think they are breaking new ground on this stuff, it just ain't so..

Look at sanctioned racing, amemiyas car , 300 flywheel hp allowed, ever wonder why he runs with the extra weight of a 20b to make 300 flywheel hp? Ever wonder why rotaries suddenly became non competitive when noise levels on tracks were lowered, and the started to dissappear al together?

As for the FC stat gears, if you had a problem in an n/a application, something besides the gear was the problem, most likely a balance issue.

More on the dyno subject..Something that makes me laugh, is that chassis dyno's were originally built to me bullshit breakers, with the advent of the internet to often they are bullshit makers... Every dyno manufacture claims to be accurate, but it just isn`t so, I don`t think any of them are unless it was actually calibrated scientifically before every use, which they are not..

mustang dynos are very acurate.2



as far as your statment about rotaries not being competitive is bullshit , we race nationaly in E production, at the run offs this year and last and even the year before almost half of the feild where rotary powered. there are alot of gt3 cars running and winning alot with rotary, there are a good number of rotary running in gt2 aswell and winning. hell there is even a hand full running in gt1 and last year a rotary one the national at sebring.



that is not to mention the rolex series where speedsource killed it the past few years with the 3 rotor rx8 and in st there doing quiet well as well as in world challenge ect ect ect..............



also on a reginal scale ITS is dominated by second gen rx7s



the problem is not a power issue or a noise issue its a fuel consumpiton issue as we all know that these little air pumps drink alot of freaking fuel to make power. and another issue is rotary powered vehicals are only in one car wich was fazed out for a few years untill recently with the rx8 wich took alot of rule making to happen to allow the car to compeat.



every time i open a GCR i am amazed in how much weight a rotary powered road race car in any given class has to weigh as compaired to its comp.

116db is almost enuff to make someones ears bleed by the way. i would hope that you are not using that car on the street and i would request your race tracks to have there sound testing equipment tested.

Let's table the horsepower discussion for now and get back to the meat of my question.



What should I do to make this motor as reliable as possible? Are there specific things I need to keep in mind from a build and parts selection standpoint? Thanks!

And where did all the factory cars go and WHY??? Because they couldn't make the power and meet the noise levels of the classes with p-ports and be competitive.. Cover your ears all you want guy but its a fact.

Taking a mustang dynos ouput as gospel compared to what OEM's use is like telling me your AEM is on par with a Horiba... I don't even wholy trust what comes off of my own dyno sometimes as real power figure.. for instance, look how many people post 500+ rwhp dyno charts with single walbro pumps, yet on my dyno, not one car with a single walbro has ever had enough fuel to get past 380-400 rwhp.. Is every pump I get bad or is my dyno reading a lot less than others?

You say you can make big power with a 6port right? I'll bet its a **** load quieter than a p-port at the same power level, or at the same noise level, the 6 port will make more power than the p-port. Thats the whole deal behind the renesis, low overlap, low noise, cleaner motor, more power than previous sideport designs.

If my track ever gets noise limits, the p-port will become a door stop..







As for building it, use new style rotors with the reliefs pre-cut, if use steel seals you need to clearance them in the slots forextra gas clearance. Use a turbo oil pump run FD oil pressure regulator, baffle plate is a must.

Even if your e-shaft is new, check the runout, the newest e-shaft I had was the worst, I went through a box of them and found one that was dead straight. I have never had a need for aftermarket balancing, I use the j-spec way of making sure its balanced well enough to live, but if you have access to it, and you are using mix and match parts, probably a good plan.

As for housings, I dunno, I make my own, so I can't comment on the quality of whats out there.

i will disagree with your statment about the rx8 rotor use unless you EDM or machine the apex seal groove to full depth to accept a standard seal from previous modle years. there are also some other minor things one needs to be aware of with the rx8 rotors aswell, like the squash area and the side cuts are designed for a side port motor and i read someplace and talked with great lengths with Drummand , Prather, Lemon, Gould and Riviara about differnt ports and the use of the rx8 rotor. everyone had there opion.



i also had read someplace that though the rx8 rotor is a 10/1 rotor the over all dia is slightly undersized from previous models and talked with Pineapple Rob about that for about an hour one day.



if your going to build a PP motor and have the rotor housings ported for the PP use the REW housings due to the port timming for the exhaust aswell as the material they are made with. that is if you are not going to use the FMR housings.



and maxt mazda is backing each and evey one of the reginal, national and pro level racers with the Mazdamotorsports program and Speed source has a full factory backing in the Rolex series. and about the noise , speed sources 20bpp rx8 is one of the more quieter cars on the race track and one of the best sounding at that. the damn DP cars are way louder. and then there was B&K Autosports, the guys who brought back the rotary in the ALMS wich was a wisconsin based race team , not to far from my house that ran a 20b PP in LMP2 but due to the owners lack of knolege and willingness to spend enuff time they really never went to far once Porshe brought out the Spyder car.



as for the mustang MD1100 vers any other dyno on the market that i saw at PRI in full use, the mustang was the most realistic there. and there numbers are usualy lower then any other dyno due to the load cell and weigh calcuations. if you enter in the proper weight, proper final drive of the vehical and rpm match for your pull the mustang dyno is going to give you spot on results. ever see a drag race done on a mustang dyno or a top speed run. we did both with ower race car. and the Top speed was within .01mph and the 1/4 mile time was the same as real world, et and mph. i have never been able to tune a single 255 pump on a mustang to more then 400 to 425whp where as on a non load cell dyno that same car may say over 450 to 500whp. t



and to your , nothing is better then factory numbers comment, um mazda now has not once but twice fucked that all up by first claming the 99 miata was making more power then it truly was as well as the rx8.

I'm only curious about your slide throttle bodies. I am in the process of making a set for a PP motor and they are 95% complete. Are your already made, or are you buying them pre-built from someone? What are you doing for a throttle position sensor?



Info on the slide throttle woulds be great.

Haven't started building anything yet. Really wanted to understand PP motors first. Sorry,



JV

Everything sounds fine so-far.



I would not use steel apex seals without a rev limiter. Real hard on the chrome in an over-rev.



I did one home made 12-A Pport and we raced with a Madeville built factory Pport engine. About 310 HP at 10,000 RPM.



Keep the EGTs under 1650 at full tilt, and it will last all year. I would use carbon apex seals. No wear at all.



If you do the RX-8 rotors have a known name shop do the apex seal grooves, as they are too shallow for regular seals.



Our side port 12-As were by Daryl Drummond.



Lynn E. Hanover

lynn i talked with drummond at the runoffs for about an hour. dude has some crazy stories from past to now. man that guy can talk a guys ear off.

He knows it all. Who built what. How much power it made. And has tried everything on a dyno that anyone ever thought of.



I would love to work for him.



Lynn E. Hanover

ya by lookin at the guy you wouldnt expect him to be a gear head, he just doesnt fit the profile ya know. he looks more like someone who would be sitting behind a computer desk trouble shooting some micro soft stuff not in a shop porting a rotary .

I don't even know what you are arguing anymore, you are all over the map here...

Before you reply , read a rotary racing history book, it will save us both a lot of typing..

Back to dyno's, you don't seem to get it, the only thing one particular dyno is accurate to, IS ITSELF.. for the last freaking time..

Lynn, thanks for the post.

116 decibels is roughly 40 times louder than 100 decibels. Logarithmic scale, and all. Every 10 decibel increase means that it is ten times louder.



I had a car that would measure 123 decibels inside the car while tooling down the highway. Not rotary powered, that came much later. The stereo had to be heavily enriched to be heard over the din, our gauge could only read to 126 but it would just barely peg it out.



A few years ago, I noticed that I couldn't hear very quiet things anymore. In a quiet room, I used to be able to hear my heatbeat. Now, a high pitched whine like a television capacitor drowns it out. Ever come home from a concert or get out of the car and everything seems to be razor-sharp painful loud for a few hours? That's the aftereffects of hearing damage. It's cumulative and it won't come back. I'm a lot more careful about noise than I used to be. Now if only I could break my habit of staring at this high-resolution light bulb!



2mm seals can withstand a little more RPM than 3mm seals, iron versus iron. I suspect that the differing information will make sense once you chart who says what versus who builds what.



High flowing exhaust systems can be made relatively quiet, but there's a lot of dark science involved. One trick involves a chokepoint in the collector to acoustically decouple the header from the rest of the exhaust system. Many hours on the dyno to get it right. After you do all that, you'll still have the intake noise to deal with, which will be shockingly loud on a peripheral port engine. It can be louder than the exhaust once you get even a moderately quiet system put together.

thats true, lots of noise out the intake! i can fire mine up without the air cleaner lid and the neighbors come out an tell me its shaking the whole house.



building the engine is really straightforward, its exactly like building a stock engine.



i run the carbon seals, i have no prior experience with them, but all the experienced people were warning me about detonation. i actually have gotten the engine to ping a little, it does the rx8 bird chirp noise, at around the same 2000-2200rpms. performance vs price they work



id run the 9.7 rotors, we know they work, no fancy machine work involved.



mine's a 12A so i set it up like the competition book, so i run about an 8" intake manifold. i did mine the same way as maxt, its ALL new parts, rotors, shaft, gears, housings, etc. i did have it balanced too.



exhaust is KEY, both for power and noise. my next step is to go to the dyno with a pipe cutter, and find the right header length, it does make a HUGE difference. next step is mufflers.