lastphaseofthis

iTrader: (8)

in my case.. it was the bottom gear split in two, on the 1st gear set, this was after repeated 6-8k clutch drops, but no wheel hop. many years ago, and i learned my lesson.... wait, no i didn't.
soo off topic....

in any case, do you want 100k miles out of an engine, or do you want power? assuming N/a..... Peri Ports were made to make more power, and at a higher rpm range. a stock port motor vs a pp running at 80% wot 5-8k is going to last the same, but rpm for rpm the peri port will make more power...but here is the points i will make

A. the stock motor COULD be driven at cruise and yeild ~20mpg and 100k miles. The pp simply won't.... it maybe could hit the milage, if it was mostly used at 30% or less throttle, and 2-4k rpm where it going to make alot less tq then the stock, and have horrible MPG.

B. the peri port COULD be used at it's high rev range 6-9k(+) but the stock motor wouldn't benefit from it, or simply couldn't.

fidelity101

iTrader: (11)

yeah that will break anything mechanical, shock load.

I'm surprised you didn't snap a half shaft first but without the wheel hop I guess you're not bending the axle at all so it should hold up "better"

lastphaseofthis

iTrader: (8)

it was a GXL LSD. i was err... "le Drifting". drops happened at 10-20mph in 1st. lots of over revving...

peejay

Except a peripheral port WILL make more torque than a stock engine at 2-4krpm. Unless something is horribly wrong, it will make more torque at 2k than a stock engine will make at peak.

See, this is why I built a peripheral port engine. I wanted to say "look, all that is BS" and amazingly enough I was right. Got about 20-22mpg and lots of grunt.

Even my 6-port bridge port engine makes more torque at 2000rpm than any stock N/A 13B makes at peak. This engine is 20 wheel ft-lb weaker than my half bridged T2 engine, which was about 15ft-lb weaker than your average peripheral port...

j9fd3s

iTrader: (3)

Except a peripheral WILL make more Tq than a stock engine @2k. i drove my 12A PP back to back with an RB exhaust/sterling carbed stock port 12A car, and keeping the P port under 4k, its still faster.

i'm not sure about mileage yet, but i can do 1 track day on a tank of gas, while my FC friend uses 2 tanks. so when you're on it, the PP gets good mileage...

rx7freak13v

thanks Peejay and j9fd3s for building a pp to demonstrate to the community how BOSS they they are and giving people such as myself more hope beyond everyone's bs about how 8yr old children playing on power wheels will have more tq under 4k then the most extremely ported 13b. i can't wait to finish this build so i can show dyno results.

are you guys running efi or carbs?

i do have a few questions, i'll probably end up starting a new thread on pp design. but before i do that, a few simple questions that you pp guys should be able to happily answer for me.

first off, how high do you guys rev? (where is your peak rpm)

second, i know that wih the full cut bridge port you really want to try not to use 2 piece apex seals to prevent the small peice from falling through the intake port. what do you guys recommend? ceraics are out of price range and carbons don't last long enough on the street. i read somewhere that aluminum filled carbon seals last around 30-40k miles when used as a dd plus track time, any input on these? i was thinking about Als unbreakable apex seals, what do you guys think? i know apex seal choices have been covered sooooo many times but there is alot of controversy on the subject. i have read about people using stock seals on pp engines but i then others say "those are too heavy to rev blah blah" and get responded with "stock seals can rev to 9k, they'll work great". but when you spend the money to cover all the machine work for engine clearencing you want to choose the right apex seal. something that can handle some mileage and take some abuse. should i send in the apex seals when i get the side face and tips clearanced on my rotors? and the apex seals need to be clearanced too right? im going to be moving for school and really need this engine to handle some miles plus take some abuse at the local solo2 events. that's why i decided on an na build. they love abuse lol


my other question is on pp angle cut through the housing. some go in at 90* and others say to go in at a slight downward angle, what do you think? also should it be a circle or, reducing the closing edge and moving up the opening edge but making it more square like a racing exhaust port? that should reduce overlap while retaining the same amount of intake volume. or should i just stick with what works, a circle lol. "it's never ending.it has no start or finish. it's everlasting" ----he he, movie quote. bet no one knows it lol


anyways lets bounce around some ideas and thoughts to see if i should dedicate a thread port design.

thanks guys

j9fd3s

iTrader: (3)

i read a bunch of crap about how unstreetable the PP was, but it turns out to not be that true. it is loud, and it doesn't like low RPM part throttle, but the loud part is fixable, and the low rpm part is actually also mostly fixable too.

anyways, i'm running a 48IDA, mine whole engine is basically setup like the competition prep manual, as its a 12A and at the time it was the best guideline to go by.

at the moment i'm running a stock 12A air cleaner, which does not flow enough, but it does filter and it keeps the noise down. so peak RPM is about 6500. with a proper air cleaner (or nothing), this will come up by 1000, and then i need to redo the exhaust, and then i'm expecting peak rpm to be about 8500-9k. i think i'm making about 180rwhp, and it should come up to about 220

mine is a 12A, so i just bought carbon seals, its really the only choice. even if its just because the carbon seals are easy on the rotor housings, which aren't easy to get for a 12A. even if it was a stock port i'd consider carbon seals for a 12A just for that. the fact that they can take more RPM's was also important in the PP.


on a 13B you have a choice, as the 2mm stock seals still work at a higher rpm, i've seen dyno's up to 10,500rpm with the stock seals. shoot we ran our IT FC to 9400rpm for a season on stock seals and didn't have any problems. carbon seals might make a little more power up that high, and they will be easier on the housings, but they also wear quicker (mazda quotes 1mm every 60,000miles on a stock engine)

so with seal choice you need to really think about how long you need it to run, 30,000mile apex seal life, is like 300 track days, or 7500 quarter mile passes, its a LONG time

the MFR housings have the port cast straight. the RB housings aren't, but it might be that it's easier for RB to fab the thing at an angle, because the intake port does lie on a curve. i'm not sure its that important.

there is an SAE paper on the latest Pport design, if i was going to do another engine i'd just copy that, it works. reducing overlap will help, but you can tune around it. my ports are the older higher overlap timings, and i can get it to drive remarkably well. it does take lots of tuning though. a stock port is happy at any AFR from 10:1 to about 15:1, but the P port isn't! the AFR range where its happy is much narrower.

i built my engine from new parts, i did check all the clearances and things like the rotor to rotor housing clearance were right in the center of the spec, so all i had to do was clearance the seals and assemble.

i don't know about abuse, but yes peepers does like to be driven hard, it will drive on the street, but its happier @wot.

peejay

My P-port was also a 12A, but EFI. Due to the overly restrictive exhaust and a poor choice of throttle body it didn't make stupendous power, unfortunately. Going by pulsewidths and a little math it was maybe 150hp @ 6000rpm, a bigger throttle body would have uncorked it for sure, at peak power I was seeing roughly 3 inches of vacuum, which doesn't sound too bad until you realize that under engine braking it only built about 15", so the range of manifold vacuum relative to power output is much narrower, 3" is like 2/3 throttle with a properly sized throttle body!

So let that be lesson 1: Engine must BREATHE in order to make power. Don't skimp. 48mm (on a 2-barrel IR setup) is good. 51mm better. 55mm even better. With EFI you almost can't go too big. The high power drag guys are running 62mm units.

I've gone to bridge ports now because it's a lot less screwing around if you're constructing your own parts. 13Bs because I can't find 12A parts anymore and the extra displacement is nice. I've run Atkins 2mm seals to a 9300rpm shift point with no issues, 10,3 by accident, engine holds up fine. Last a good long time, too. I build half-bridge engines because I'm doing EFI and it's nice to have the fuel injectors (or primary, if staged) only injecting into non high overlap ports, makes for extremely good drivability. That said the bucking with EFI on the peripheral port wasn't very bad at all. (I did have my injectors placed pretty high up in the intake manifold) Very easy and quick and cheap to tune the drivability compared to changing jets and air bleeds and emulsion tubes and who knows what else and then trying again.

I have a video on my YouTube channel of the peripheral port idling at ~1200 with EFI, real smooth, just a little bit of a blrpblrp in the idle...

j9fd3s

iTrader: (3)

this is mine, http://www.facebook.com/photo.php?v=...type=2&theater

its the first start, so its cold. i have that dual tip thing, it makes it neighbor friendly

rx7freak13v

mr. peepers sounds amazing!!!!! i can't believe how much adding that twin tip quieted the exhaust lmao. that's ridiculous.

anyone else have video?

cavemag

A quiet pp that doesnt idle at 1500. What type of black magic are you using?

j9fd3s

iTrader: (3)

a screwdriver!

Rub20B

None of you guys run a thermometer in the box? With the miata we can run about 20 min from cold on the track without cooling for the box, after 25 min it starts to shift worse and worse and worse and temps are approaching 150 deg C, even without a thermometer one could know its was too hot by the smell of burnt 75w90.. in the beginning we also tought it would not have been necessary as its a stock renesis engine with stock rx8 6spd, but it seems with agressive driving and shifting at 8k5 most of the time there is a need to cool the oil

rx7freak13v

i actually thought about running a trans cooler and a rear diff cooler. a couple of oil coolers and some low psi pumps so do the job nicely.i figured could add a sensor into the trans while the trans is apart for the rebuild. any recommendations of which sensor to use?

peejay

Most people in the US running peripheral ports are drag racers or otherwise not running for more than a couple minutes at a time. Most racing series that people run rotaries in spec stockport engines, or they heavily restrict porting... plus the races are usually 20 minutes long anyway.

Besides, even in the "restricted porting" classes, people are running full-race gearboxes (Saenz, Hewland, etc.) so the issue's moot. Things are funny here, restrict the power down to boring levels but allow everything else.

Rub20B

Which sensor you use depends on how you will read it I guess.. I am using standard VDO fluid temperature sensor for the engine, gearbox and diff oil, conntected to a race technology datalogger/dash.

If you would like to keep the budget to a minimum, one could just use the same sensor as the oil temperature sensor and share the gauge with a simple switch

here we have 95dB noise limit.. very, ehm, not nice for a rotary.. even with a stock rx8 rear muffler (no cat) we were slightly over that. With a PP you could just as well not participate

Tanj!

iTrader: (5)

Actually the next closet gear set is the USDM first generation 626 which was RWD. Like the Miata the input shaft is longer than needed for a RX7 so the guts can be put into a RX7 gear case and the input shaft shortened and the proper rear casing installed.

The primary problem with the NA transmissions are the weak synchros. Talk to any of the guys racing ITS and that's what wears out first. The rest holds up fairly well. When mazda redesigned the synchros in 94 for the Miata it was a huge improvement. They still wear out but they last much longer and take more abuse.

Kenku

From talking to Tom Thrash at Elkhart once, the problem with the 626 boxes is that the input shaft is smaller diameter than the later gearboxes, which can lead to it snapping when combined with a small diameter clutch that doesn't damp out engine vibrations as much. </anecdote>

RotaryEvolution

iTrader: (30)

food for thought on the engines.

carbon seals do not last very long period, and don't assume that if they fail they will salvage your parts because there is still steel springs under the seals.

the 787B used ceramics, not carbon. ceramics last much longer and are as light as carbon seals. difference is $, ceramics merely cost 3-4 times as much but the benefit is also there with the cost.

steels will chew up housings at higher RPMs, that is why they aren't used for high revving n/a engines but they will last infinitely longer than carbons, the sacrificial lamb is the housings.

i plan on making my own single piece ceramic seals to go along with my 4 rotor project, figuring out a way of trimming the seals will obviously be challenging unless i opt to just send them over to water jet to be cut(but i have a hard time leaving tight tolerances on very expensive materials to the inexperienced).

RotaryEvolution

iTrader: (30)

also, S5/6 tension bolts are not superior. of all the engines that have passed through my hands the ONLY failure i ever encountered with was on a S5 engine where the bolt sheared off at the threads, possibly due to resonance FROM the ribbed section.

Rub20B

Depending on how much you want to trimm off the apexes, it can be done relatively easy with expensive sandpaper, or bring them to this guys who cut diamonds.

I also cutted the cermic seals for the small single rotor kart engine, first tried 12a carbon cutted, but these only lasted a few hours until on cracked in the exh port, housing was fine altough. Reason for me using the carbons was that the stock ceramics where way to long causing a unsleaed track on the rotor housing where the tip is. Now I grinded the ceramics to the correct length using an old grinding wheel from a diamond guy, in teh lathe with a small piece so the apex is always thrue to the disc, then with some diamond powder it grinded with relative easy and gets a mirror finish.. motor is still going strong =)

peejay

Interesting. Off to SoloMiata and a little math:

Rev drop with shift at 8000rpm:

626
1-2: 4525
2-3: 5702
3-4: 6172
4-5: 6864

Miata
1-2: 4816
2-3: 5635
3-4: 6015
4-5: 6512

So the Miata has the edge on the 1-2 shift, while the 626 box is better everywhere else, although probably not enough to justify the apparent weakness. Which gears are you concerned about? I wonder what the transfer ratio difference is, and if a 5th from something else can be stuck on the Miata box to tighten that up further. FCs have a tall 5th, for instance, but a lot of that is the transfer ratio - put an FC 5th on a Miata geartrain and you get something else entirely.

Oddly, I can actually FIND the 626 boxes, and they're a ton cheaper than the Miata units. For some reason, anything with Miata on the label makes it really expensive. Ain't gonna pay $500 for a junkyard trans that I'm just going to break in a month or two.

I don't really seem to have synchro problems, it's the bearings that go away. Latest failure I'm running across is the bolts on the center plate backing out. One bolt in the gearset will ruin your whole day I think on the very last one, I blew the 5-R stack off of the countershaft. Horrible noises after the 4-5 shift, and later when I tried reversing, the trans locked up solid. Still have yet to pull it apart. Different uses make for different failures.

The 1500rpm comment earlier inspired me to make this video in the Summit parking lot. Went there to pick up gear oil for the new diff and an aluminum carb hat for "something"


The stereo isn't up very loud at all. Not a peripheral port, but still, that's 1000rpm idle with a gobs-of-overlap engine. (AutoGage tach: It's precise but not accurate - I trust the MegaSquirt's tach reading)

Kenku

In fairness I don't know that it's that much issue for most configurations... he was just explaining why he ran the Miata box in preference, as he found that with his... I forget if it was 4.5 or 5.5, one of those, but with that and the Mazda comp flywheel, well, there's nothing to smooth out vibrations and power pulses. He commented that even with a competition flywheel and the 7.25" dealie it should be fine.

j9fd3s

iTrader: (3)

i lol'd when i heard the radio, what kind of sorcery is that!

peejay

And the best part, the RB exhaust system has about half the backpressure my old cobbled-together 2.5" straight through system had - measured just after the header flange on the outboard pipe, I see 2-2.5psi max.