RB_eater

iTrader: (1)

The car is a S5 N/A, I'llbe using it as a daily driver so I decided to replace the leaking seals in the engine. I decided I could port it a little while I'm at it but of course the car as to remain streetable. So my questions are is it possible to do some mild port job without a template? If not where can I find a 6 Port template? And how much power would be gained? 10-20hp would be really nice.

Aaron Cake

iTrader: (1)

Mazdatrix sells the templates.

RXBeetle

I got this template from Mazdatrix
http://www.mazdatrix.com/getprice.asp?partnum=49-2226P
I also used their exhaust template but I torched/ground out the diffuser in my exhaust sleeve first.
http://www.mazdatrix.com/getprice.asp?partnum=49-22215
The diffusers quiet the exhaust a lot but are also a nasty restriction. I removed the sleeves and torched out the diffuser. You can also just swap for 4 port exhaust sleeves.
Motor isn't running yet so I don't have results to post sorry.






Hope that helps.

RB_eater

iTrader: (1)

Thanks guys, I checked the mazdatrix templates but they offered very little info on their site. Anyway now I should be able to move on with my rebuild.

rotaryinspired

iTrader: (3)

If you port down that much on on the exhaust of a N/A car you will shorten the power stroke. You can get away w/ it a little in turbo cars as the turbo will compensate for the shorter stroke.

I belive you can do some more w/ the 5th and 6th ports that shown in the previous pictures.

I have attached pictures of secondaries I ported and also the same exhaust porting for the same motor. This motor pulls very good down low and rips up top. I also moddified the sleeves to work w/ the porting on the 5th and 6th ports.

I personally don't believe the exhaust needs to be changed much on a streetported 6 port motor. If you remove the diffuser that is good. I believe you only need to go up a couple of millimeters and also a touch wider again by a couple millimeters. Be carefull going wider.

RacerXtreme7

iTrader: (2)

There is so very little effective moment arm the rotor has over the eccentric shaft that late on the expansion process that its more efficient to go ahead and expel the exhaust earlier then it is to keep the expanding gas in the combustion chamber because it has such little actual work making it to the shaft. Assuming you are looking for performance and use revs higher then 3200 to redline. The engine will work harder pumping out the exhaust because it has little time to expel it, this amount of work exceeds the amount of work that keeping it in longer puts into turning the engine. In other words, it uses more energy to pump out that expanding gas then that expanding gas puts energy into turning the engine. By expelling it earlier, you get more open time for the gas to escape instead of pumping it out. Hence why everyone and their mother except for a few (who ignore physics, make up their own, or don't listen to those who have DIRECT LONG INVESTED YEARS in the nitch of rotary porting) port down on most performance orientated rotary engines. This isn't theory, is physics!! And porting UP on the aux ports is pointless too. Their closing time is already later then peripheral port close timing. Your not going to be getting anymore air going into the combustion chamber by a later closing unless you have some nice custom intake manifolds and / or raise the redline. All you'll be doing is causing reversion. This holds true for 86-91 6 ports, the older style 84~85 GSL-SE can go higher or later closing on the aux ports (as long as you do some intake mods as well) because their close timming is earlier then the later engines.

BTW, RxBeetle, nice port work and nice job on the exhaust sleeves. Make sure there is enough clearance to allow the rotor housings to expand and NOT collide with those purty exhaust sleeves and warp the housing causing apex seals to get destroyed.

~Mike..............

seandizzie

iTrader: (1)

Should the opening edge on the exhaust be flat as well?? Will being rounded make hot spots on the apex seal??

RX7 allnight

you removed your sleeves in your N/A whats the power gains form this? how are the noise levels?

RacerXtreme7

iTrader: (2)

No, he did not remove his sleeves, he removed the sound defuser. Gains are minimal by itself. Its when you add full porting, full exhaust, better intake, tuning, etc etc when you'll see full gains of removing the defuser. And the gains will go up with each mod, so its hard to say exact numbers.

~Mike.............

scathcart

Everyone except Mazda....
Opening timing of the stock 13B rotor housings is 71 degrees. Exhaust opening timing on the MFR PP housings is 73 degrees, 2 degrees later. Exhaust closing is significantly moved up, occuring at 65 degrees ATDC as opposed to the 13B 48 degrees.
So has Mazda just not directed long hours of research into the rotary engine? Porting down for certain applications will cost power.

RXBeetle

I am by no means an expert or even a novice when it comes to p-ports but it is possible that they moved the exhaust port closing time later increase the overlap. Overlap with a tuned exhaust (strong scavenging effect) will draw the incoming air charge right into the chamber. I just don't know if a p-port housing is the best apples to apples comparison for our application.
Emissions standards are another thing to consider for the stock port timing. Any earlier and more unburned fuel would escape, any later and more intake overlap occurs without the benefit of a tuned exhaust.
I'm not trying to start a debate over why Mazda did what they did I'm only concerned with what works best ignoring the constraints they were limited to.
I tend to agree wtih RacerXtreme7, open early, it's not doing much if any mechanical work so let it be free

I'm seeing the MFR PP housings at....
IO:85*-BTDC
EC:65*-ATDC
That's 151* of overlap!

most of the stock port motors run...
IO: 32*-ATDC
EC: 48*-ATDC
Only 16* of overlap.


Thanks. I have a good .030"+ gap between the sleeve and housing. I was concerned about heat expansion as well. My motor will be run NA for a while until I feel confident with my tuning abilities (megasquirt) but a turbo is in the plan.

RXBeetle

Some Yaw Power knowledge:
http://www.yawpower.com/techindx.html

11. 135° ATDC The expansion stroke continues, but the torque transferred to the output shaft is now down to about 35% of its peak.

12. 180° ATDC The exhaust port is still closed, and the torque transfer to the eccentric shaft is approximately 15% of its peak.

13. 225° ATDC At this point, the exhaust port has been open for approximately 30°, and exhaust flow is quite high.

14. BDC of the exhaust stroke. This is typically the point of maximum flow through the exhaust port. Even though the chamber volume is not decreasing at an appreciable rate, the chamber pressure is very high, and this is responsible for a large percentage of the total exhaust flow.

15. 90° ABDC The chamber volume is decreasing, and is 45° away from the point of maximum rate of decrease of the chamber volume.

16. 180° ABDC The exhaust chamber volume continues to decrease, and at approximately this point, a bridge ported, or peripheral ported engine will have started to open the intake port.

17. 225° ABDC The exhaust port is still open, and the chamber volume is decreasing at a relatively slow rate. At this point, a mildly bridge ported engine will have just opened the intake port.
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As performance, and rpm requirements increased, it was discovered that by opening the exhaust valve before BDC the residual combustion pressure could be used to help evacuate the cylinder at the beginning of the exhaust cycle. This is referred to as the blowdown period, and is responsible for approximately half of the exhaust flow. In theory, this will reduce thermal efficiency by releasing pressure that is still applying force to the crankshaft. In practice however it was determined that the reduction in pumping losses far outweighed the loss of pressure at the end of the expansion cycle. Since most of the useful work is done in the first third of the expansion cycle, the pressure loss caused by early exhaust valve opening is minimal. This also applies to the rotary engine. Referring to last months article you can see that the exhaust port of a stock engine opens approximately 75 degrees before BDC.
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As the exhaust port opens, (#13 in the illustration) the high pressure in the combustion chamber will force the gasses through the port and down the exhaust system at a high rate of speed. This, as you remember, is the blowdown period, and a large portion of the gasses will exit the chamber at this time. At the same time that the flow is initiated, a high pressure wave will travel towards the end of the exhaust system at the speed of sound. (Note that this high pressure wave will help to propel the slower moving exhaust gasses with it.)

rotaryinspired

iTrader: (3)

There is a reason that Mazda moved the ports to the side plates in the renesis. The exhaust port timing is actually later than previous 13b's.

Kenku

While I agree with the rest... as has been mentioned, Mazda doesn't agree with this part.

http://s39.photobucket.com/albums/e171/KJ_carstuff/SAE/ Scanned this a while back; SAE paper on development of MFR peripheral port timing. They also come to the conclusion that because of rotor geometry, actual overlap effects are far far far less than is suggested by just port timing numbers. Interesting reading even if you don't agree with the exhaust numbers.

Kyrasis6

Yea I read that in another post and did a bunch tracing on all the parts, the area in which gas could travel is minimal.

Judge Ito

i done a **** load of 6 port engines. most made decent horsepower. I'll post a short video of a 6 port bridgeport..

RXBeetle

^^^ Please do! mmmm rotonography

True, kinda. The Renesis has a much later EO and earlier EC timing. Basicly a shorter exhaust cycle all together which doesn't support either case (port up or port down)
EO: 50* BTDC
EC: 23* BTDC
As opposed to 75,48 of a regular ole 13B
They were shooting for ULEV standards. They didn't meet it but did manage LEV-II standards. Early opening exhaust and overlap means increased unburned hydrocarbons.
http://www.turnerdr.com/techinfo.asp
Some info on that.

That SAE paper is heavy on P-port intake data and intake/exhaust length tuning. But does not cover the effects of port timing at all. It only states the IO IC EO EC of the housing not the effect of change. I do appreciate you posting it. I have been trying to track those down for a while.

RacerXtreme7

iTrader: (2)

You’re a genius yes?

Sorry for the sarcasm, but in your haste to argue with, or to prove me wrong with your superior rotary knowledge, you failed to spot the obvious. (again, more sarcasm sorry, I must be in a pissy mood).

"Opening timing of the stock 13B rotor housings is 71 degrees. Exhaust opening timing on the MFR PP housings is 73 degrees, 2 degrees later."

Umm no, that would be it opens 2 degrees EARLIER. Those open and close timings are given in BBDC and ATDC, BBDC meaning Before Bottom Dead Center. The larger the number the further from Bottom Dead Center. So, the Factory PP housings OPEN EARLIER and CLOSE MUCH MUCH LATER. Thanks for proving my point.

I will agree however that in some cases porting down will lose power. Like, below 3000 RPM-ish give or take 1000 or so (it really depends on the system and supporting pieces along with how its used).

I knew as soon as I clicked the submit button that I was not clear enough. When I type long winded and very clear post, most just skim it and miss damn near everything including the main point of the post. So yeah.... when I say "porting" I mean it in a verb kinda way, as in actually mod-ing a stock port. And I also assume most people in here drive there cars and we are talking about performance STREET driven cars or even street given cars that are raced (The 1st / main post and title is 6 port porting after all), so I was naturally excluding 2" ID 14" long large P-port intakes that NEVER close (yes, their in effect are never closed) and open header exhaust. It’s much harder to dump an exhaust through a full street car exhaust system be it straight through or not then it is a full race open header. Free intake and exhaust systems lend themselves better to port overlap.

BTW, look at any MAZDA RACE supported street and or bridge ported engine as well, you'll find the exhaust ports both ported UP and DOWN when compared to stock.

Porting down also benefits turbo engines a bit more too. Not only does it give more open time, but the extra energy of the still burning and expanding combustion gases help with turbo spool up.

lastely, Racing Beats open timing for there exhaust ports are 84* BBDC for street port and an extremely early 88* BBDC for there "J-Bridge" porting. WOW, those guys have no idea what their doing even though they have been in the business for THIRTY YEARS and have been MAZDA FACTORY SUPPORTED for NUMEROUS race endevours.

Your kidding right? Your comparing apples to oranges my friend. The reason the Renesis has a later open earlier close timing is several reasons, NONE or which are for performance. The performance gain in the newer engines is tuning, intake system, fuel system, LARGER and LONGER duration intake ports, less internal friction, more exhaust port area, lighter rotating assemblies thereby allowing HIGHER REDLINE. Horsepower is simply a function of torque over time, so the higher the redline the higher the hp rating. You'll find if you open the exhaust ports on a RENESIS making it open earlier and close later that you'll be making more power (assuming again the guy doing it tunes it and runs a free-er flowing exhaust). One reason it opens later is because there’s soooo much more area now (each rotor has TWO exhaust ports now instead of ONE) it doesn't need the longer duration. Another reason is because it closes earlier, the intake is now able to open earlier without the associated overlap of the older engines there by making more power with the intake charge being better (higher VE). Another reason yet and probably the biggest is EMMISSIONS. Keeping that expanding and burning gas in longer gets a more complete burn thereby leaving fewer hydrocarbons. Another nice feature with the side port exhaust as far as emissions goes also is any unburned fuel and or oil that collects at the apex seals gets to go around once again an entire engine cycle for another chance to get burned off were in the peri port older exhaust it simply got flung out the exhaust port and into the atmosphere. The earlier closing is to avoid over lap, which at lower RPM dilutes the intake with exhaust and causes misfire (READ: more dirty emissions). Again, the intake is allowed to open earlier now because the earlier closing of the exhaust.



I'm not sure what your agreeing with and not sure why you say MAZDA does not agree with me. Those papers (which I've read before) don’t say much if anything about port timing high low or indifferent. Could you maybe point something out that I'm missing?

~Mike..................

RacerXtreme7

iTrader: (2)

Sorry if I repeated some things, theres been a few post after I started to reply well over two hours ago now (I'm at work and had to step away from the computer when I first started to reply). and didn't submit till just now (several post later then I originally started).

Just making it CLEAR, my above post is refferancing exhaust ports except were I say intake ports (RENESIS examples).

~Mike...........

diabolical1

iTrader: (3)

+1

Kenku

Well, that extending the intake duration even more is futile is one (personally, I'm of a mind to try smoothing the runner signifigantly with Devcon, but that's another issue)

The exhaust port timing I'm referring to is on page 7; mostly just to say that out of all the port parameters they went optimizing on the computer model and then testing on the dyno, the exhaust opening stayed constant. It could be argued that they couldn't open it later because they were based off of productionized castings, but they didn't go opening it earlier either. And yes, it's a full bore peripheral port... but if anything, wouldn't it be *more* optimized for high-RPM useage than something that was developed for a streetport?


I know Mazda had all sorts of port setups over the years, but like everything else their understanding of stuff matured as time went on. What're the specs on these MFR street/bridge motors you spoke of, and when were they made? This paper represents the latest published development of the factory race motors that I know of.

RacerXtreme7

iTrader: (2)

Ok, so I've went ahead and read through the SAE papers again and still haven’t a clue as to were your standing and how your using this SAE paper for support. You realize that the bandwagon that you jumped on had a horrible wreck and flipped over due to wagon driver error of confusing some geometry right? MAZDA supports what I'm saying, not what scathcart or you are saying. The term was [Me, racerXtreme7]"everybody and their mothers" Him scathcart "Everyone except Mazda...." Well, he used MAZDA unknowingly to prove my point, so exactly were is it that you’re standing???? Stock open 71*, MAZDA P-Port open 73* which is 2* earlier. You seem to be taking his side, and still using MAZDA for your side of the argument yet plain ol' text shows MAZDA is on my side. That particular SAE paper and the exact PAGE you list is a study of VE of a particular PP engine how dicking with the INTAKE affects VE thus increasing engine output at a very specific RPM (9000 to be exact). Not an all know and telling study of VE, but a study of VE on THAT PARTICULAR ENGINE, with intake variations. [Quote straight from the study "changes in VE was examined using the simulation when one of the factors of the INTAKE PIPE length, diameter, port opening area and port timing were changed." notice it makes ZERO references to exhaust port timing, shape, exhaust pipe diameter, length etc etc etc. Although in the little picture it does show that they closed the exhaust earlier. Well, if they can close it earlier (effectively adding material to what was there) I suspect they could have added material for later closing as well, but again, the study was concentrated on the INTAKE PIPE. Also take note, it uses the 73* open timing which again mentioned several times now is 2 degrees EARLIER open timing over the stock 13b side port engines that came in every Rx-7.

As for whole engine systems. Early opening of the exhaust is good for power. More does not always mean better. Early and earlier isn't going to make more power necessarily. Its dependant on many upon MANY factors. Lets just use a theoretical PP engine and a heavily street ported street car engine for a little exercise maybe to give some readers a broader scope of engine and dynamics instead of zoning and cluing into key words or fraises such as "porting down makes more power" as this line is a generalization.

The PPort engine has a direct path short length and large diameter intake tube. Its pretty much unrestricted straight shot into the rotor chamber at wide-open throttle. Its exhaust is of the same design, just a header going to a collector with a standard megaphone diffuser, again, none restricted as it possibly could get. Now within this engine, pumping things in and out happen easily, at idle and low load situations the thing bucks and misses and gets the usual "brap". It doesn’t have enough intake velocity to overcome all those exhaust gases creeping up into the intake due to high overlap and its intake of air and fuel is diluted with dirty *** exhaust, hence the bucking and "brap" idle. Well, a little bit of depression of that loud peddle on the right while in the drivers seat and RPM's climb and a world of difference starts to happen. That tuned resonance of an intake and exhaust system start to work, the free flow-ness of the in and out systems start to shine, the stronger exhaust pulse starts to scavenge, the air going into the engine has enough inertia now to overcome reversion and fill the rotor chamber up not only very early intake timing but also late timing too because there’s enough velocity and inertia to keep filling the chamber long after the rotor chamber has begin to get smaller. The open and close timings of the engine are all in harmony and work because none restricted intake and exhaust. This thing is sounding like a tin can full of extremely PISSED OFF bumblebees and your smiling from ear to ear as your being shot down the track. The engines time for its intake and exhaust are opened long enough to get in all and get out all possible and doesn't really require and more timing especially the exhaust because its so unrestricted and tuned to scavenge. So its open time is per all the other systems going on and is supported by every aspect of what’s going on under the hood. The rotary P-port has an outstanding over 100% VE. Yes folks, this little wonder is actually intaking in more air then it actually displaces and doing so naturally aspirated!!

Ok, now lets move on to the streetcar engine. Unlike its behemoth brother the P-port, this guy is burdened with all sorts of ****. Its intake ports are located on the side plates. It’s a staged intake, meaning only the primaries are for idle and low load/rpm situations. Its done like this to keep intake velocity high. High intake velocity atomizes fuel better and also fills the chamber more. So this engine has a **** load of intake tubing for runners. Those runners are tuned for a more civilized idle and engine operating RPM (READ: LOWER RPM range) so they have to be long. Well long ***'ed runners wont fit sticking straight out the side of the engine so they curve and twist back and forth to fit when you slam that hood down. The exhaust, its plagued with having to exit way to the rear of the car and be reasonably quite so it has mufflers and such. Even though Joe Smoe has a streetcar, he’s ignoring the environment and others around him so he has a full header, no CAT, a presilencer and dual mufflers, but its all straight through (and still ******* LOUD, anyone with a ported N/A can attest to this no matter how many damn mufflers used). It’s a pretty high flow deal, but nothing like a P-port straight up open and tuned header. Ok, so this thing is civilized, it idles, he can cruise without any annoying bucking or misfiring (audio able ones anyways) during his usual cruise to his girlfriends house. When he steps on the gas it goes..... Now what’s going on inside now.......... Well, because he has to pump that damn annoying exhaust out the engine and through (although reasonably free flowing) exhaust, he has to pump harder because the smaller tubing, more bends, longer path when compared to fire breathing P-port. So, it’s a harder job. Both engines displace the same amount statically and fun RPM ranges are close to the same although the P-Port is capable to go a couple thousand RPMs higher in range. Those MF PPort engine were mainly for endurance engines were life and RPM ranges were from 4000 to 9/9500. Though the engine could go higher and did make more power, they were kept in that range for longevity. So the fun range (lets say 6500~8000) both engines have the same amount of time to expel that damn pesky exhaust. Well, the P-port has less resistance to pump against (actually, there’s not much "pumping" going on with this engine, scavenging and blow down pretty much got that **** sucked out). Because the free flowing intake and exhaust the P-Port has huge over lap and it works great, so its effect exhaust open timing is moved later but its open time is still effective enough to get it all out (at tuned RPM's anyways). So this "street" engine has a restrictive intake and exhaust and having such huge amounts of overlap just doesn't work because air don’t like all them tubes that split into other tubes and turns and twist and etc etc. the high overlap just wont work. The pesky exhaust just wants to creep up into the intake stroke because there’s a vacuum there and the exhaust side has pressure from the last exhaust stroke. So, well we need more time for the exhaust to be opened and moving it later wont work due to overlap, so lets move it forward. Lets open it up earlier. Its harder to expel when compared to the P-Port so whatever gases that are trying to escape during power stroke phase is putting less energy into the crank at this point so late in the power stroke phase that simply expelling the exhaust earlier is easier then holding it in and then pumping it out in a shorter time period.


So you see, different port timing for different engines, RPM's, situations etc etc etc. What’s good for the goose isn't always good for the gander, but in some situations it is. Look at the bigger picture and the system as a whole, not just single aspects. Early opening doesn't make more power always in every single application. In general, yes it does though, generally and at the expense of lower power in lower RPM. Same for all aspects of both intake and exhaust port timing. There’s compromises and a certain port timing will not always lead to greater power in all situations, but you can generalize and still be true, like earlier opening and later closing of the intake WILL make greater power (in general).

The SAE paper is of a 3 rotor P-Port engine. Like I've stated already those engines were built for endurance road racing so their RPM ceilings hovered around 9000 RPM. Now if you go look at ***** to the wall this thing only needs to last a couple of races P-Port, monster bridge, J bridge, and bridge ported engines were RPMS start life after 8000 and climb into the 5 digit range, those engines have an even earlier exhaust port opening (such as the J bridge port of Racing Beat example I gave earlier). I have heard and seen were guys take MFR P-Port housings and port them further down and gain power because they raise the RPM ceilings of their engines were the housings designed by MAZDA didn't have this RPM in mind. The Racing Beat P-Port housings have this extreme early open as well, they were designed wiht 5 digit RPM ceilings in mind.

I'm not going against common logic or practice here. This is common knowledge and I’m not saying the sky isn't blue or water is indeed not wet. I'm saying they are, so if all the performance engines built by reputable shops and shade tree mechanics and huge companies including MAZDA itself over the past 30 years isn't enough proof of this basic engine dynamic fundamental, well then go find your own empirical proof and data and show me and the rest of the world were we and science are wrong. So far, all has been proving correct on my side and supported by the ne-sayers!!!!

phew, what a waste of time I'm thinking this just was............

~Mike..............

RacerXtreme7

iTrader: (2)

Holy long post Batman, someone please read it in its entirety, please........

~Mike...........

Kenku

Man, again with the overlap... I'm getting sick of the overlap thing. The chamber geometry indicates that it's far less severe even in PPort applications than people think, the paper does too, but to hell with it... been looking for an excuse to build a flowbench anyway. MFR-size peripherals don't work at low RPM because of port velocity.

Funny thing in the paper; notice when they were playing with exhaust length too? Just because they don't talk about it explicitly...

Now, that whole thing... you really could have cut that down a fuckload; "earlier opening needed so that blowdown can drive exhaust through mufflers" or something would have sufficed. I have had enough of an education that you can use big words. Frankly, I think you're overstating the difference... the Kudzus were muffled, the 792 was muffled (and evidently they spent a *LOT* of time on the exhaust in its brief career)... I can't speak for the 757, 767 and 787 because I've not seen them in person, but I'd wager they were too. Now, the BK Courage from last year *wasn't* and ye gods did that hurt.

Oh, briefly on the Racing Beat housings... everything I've heard places them as *at best* equivalent to the MFR housings, and at worst inferior. Go look up Scalliwag's housing buildup thread for drag guys who were unhappy with the available bits for one... or look at the Speedsource RX-8 using the RB housings making less power per displacement than the old endurance spec motors (even the Kudzu vintage, Kugelfischer injected ones). Designed for 5-digit RPMs my ***.

Finally, back to the issue of porting down... I still don't know that I agree, but fuckit, I'll be honest and admit that of all the streetported motors I've done none have ended up in street cars. Last one that went together was cloning port timing and shapes from a nationals-level EProd 12A; it did 235 horse at the flywheel through an IDA with the class-specified venturies, and strangely enough *that* wasn't ported down. Nor were some other pro-built 13Bs for the same class. And don't even ask about the mufflers needed to get the things to pass noise restrictions, ugh.

I admit I'm curious though... that may be a point on crappy restrictive exhausts. Might have to go build a dyno mule to see.

RXBeetle

Ok I read the whole damn thing. A+ for comedic and descriptive rhetoric, "see me after class" for not making it easy for the non-believers to accept your argument haha
I feel bad though, the topic is far from the thread subject.
The topic warrents discussion so I'm starting a new thread.
Port timing spreadsheet included! graphical coming soon! huzzahh!

https://www.rx7club.com/showthread.p...16#post6859716

Oh yeah play nice or your beer will go flat and warm