rx7freak13v

Hey guys just curious if anyone can help me with this question.

What is the typical life span of a pp na engine that revs to 9500-10k?

What is the main part that dies resulting the need of a revuild?

I've been searching tor a long time and can't find any real answers. Some people say that pp engines last less than 10k miles and other people claim to have been dd q pp engine for 5-10 years with over 50k miles easily with the usual weekend track days and the motor still runs strong. I don't underatand how both could be right unless one is poorly tuned.

Say it does need to be rebuilt in 20k miles, what us usualy the part that breaks?

I'm torn between a bridgeport build or a pp build. I'm shooting for about 260-280 rwhp all motor. Planning to run an efi 4 barrel throttle body on a projay (jaytech) intake manifold (they're taller than the racingbeat manifold and bring the throttle body farther away from the exhaust manifold, also the longer runners should increase torque) tuned with a megasquirt (because I know people who tune megasquirts for rotaries and will give me good deal)

I'm just curious on which one would last longer. If all I have to do is open the motor and replace apx seals and re close it with new o rings then that wouldn't b an issue.

Carlos Gonzalez of GNS Racing (located in west Ocala, Fl. He's a 4 time drag racing champion racing rx7's. He held a record for fastest fc for many years with a pass of 7.30 maknf 1,034rwhp on one of his streetports which are enormous) he told me tha if I dd it like any other car via babying it and then only beat on it on the weekends or track days then it would last as long as any oher engine as long as it was properly tuned.

Just wondering what you guys think. There just isn't enough info on pp engines

nvmarx

iTrader: (1)

that is corect if you just put put round in your pp barp barp it, it will last just as long and any other and only give it death on the odd weeked it will be fine bro

rx7freak13v

I hear that pp engines behave more like stock ports than bp engines do. I know that exhaust is going to be loud, but it'll be loud on both setups so not really an issue. I also underatand that it might be a little uncomfortable to drive with, but my 88 fc is completly gutted including heat and defrostees, no door panels or anything and has a stage 3 unsprung clutch with solid motor, tranny, differential and subframe mounts, so comfort flew out the sunroof a looong time ago :-) I would love a pp 13b. Anyone with firat hand experience have any comments?

nvmarx

iTrader: (1)

your car sound abit like mine haha
https://www.rx7club.com/build-threads-294/my-s4-build-nz-styles-974868/

if you go for a efi set up it will be alot more driveable

j9fd3s

iTrader: (3)

as for wear, it is going to depend on what you use the car for, and what apex seals you choose. the competition prep book wants a rebuild after 1900miles with a 9,000 rpm redline, and 2500miles with an 8,500rpm redline, and this is in road race trim, on carbon apex seals so those are racing miles, so its probably 80% full throttle over 5,000rpms.

a drag race car is wot 100% of the time, but 2500miles is 10,000 dragstrip passes.

so the road race mileage could be done in a weekend, but drag racing would take like 40 years (really!) [the drag race season is about 15 minutes of run time, or about 225 passes, which is 56 miles a season... 2500miles/ 56 miles a season = 44 seasons)

on the street it'll see much less time @ wide open throttle, so it should go much much further, and if you ran a longer lasting seal than the carbons it would go even further, the 787B ran about 4,000 miles in the lemans race....

i've driven a pretty badass 13b BP car, 230rwhp in an Rx3. it was a big full bridge, holley carb on an RB intake. lots and lots of tuning time, and it was pretty tame, it was quiet enough to be used on the street (it was actually a DD). basically it had a brap brap idle, and would buck a little under 4,000 if you weren't on it, but other than that it felt like a normal 13B, except with power, the dyno stopped @9600rpm and it was still gaining power.

i own a PP 12A, weber. the PP does seem slightly more tame, i can tune the brap brap idle away (it sucks though, why have the big port but not the brap?), it'll happily cruise down the street in 1st @2000 and not buck, and that's with a carb and locked distributor, EFI would run like stock. power i'm still working on, with the stock 12A air cleaner it peaks about 6k, however it makes more power than the FC by about 2500rpm, and then really starts pulling, its like a truck....

you will find the difference in exhaust noise between the stock port and either the PP or the BP is really small, however the BP and PP will not put up with a restrictive exhaust, so they need to flow a lot and those are usually loud. the BP/PP also make a LOT of intake noise. when i pull the air cleaner off the PP the neighbors come out from upstairs holding their heads, its not the volume its the shock wave...

rx7freak13v

I'm wanting to run a fuel injected holley 4 barrel throttlebody with the 4 barrel velocity stack style air filter. It would get tuned via a megasquirt.

The car will probably remain my dd and a drift warrior. It'll spend most of its time on the streets and then an event from time to time. The closest skid pad to me is an hour and a half drive plus $40 to perform. Ill be moving closer to the track in the next year though for school :-) . I wouldn't mind opening the motor to replace some worn apex seals and reclosing it. I'm leaning more towards super seals because they close better and are known for longer compression life. I thought about carbons but it'll b at low rpm most of the time so it would probably be a bad idea lol

I want the brapy idle. Its what I live for. I think I'm convinced to do the pp build.

How long have you had your pp 12a?

j9fd3s

iTrader: (3)

you can't run a holley on a normal p port, the P port only has 2 intake ports. no stock intake will work either.

i personally wouldn't run anything but oem seals, but the really important thing is to start with really excellent or new parts. check out the competition prep book @www.foxed.ca

my PP is old, but low miles. i bought the parts in 2007, built it in 2008, and it did sevenstock in 2010, and its first trackday in 2011.

rx7freak13v

How many miles are currently on your motor?

What's apex seals are you using?

Did you use hardened stat gears or oem ones?

Mfr or oem rotor bearings?

I just realized hardened stat gears and mfr rotor bearings are almost $700 plus seals and such. No wonder why everyone goes the boosted route.

The way finances are, I may have to reconsider.

Thanks for all your input

j9fd3s

iTrader: (3)

mine isn't a street car, so it doesn't have many miles on it, when i drive it on the street the neighbor tells me its loud enough to wake the dead... so the odometer says something like 40..

i used the carbon seals. the price was right, and if i break one it should be pretty easy on the housings i can't replace! i have the hardened gears, but stock bearings. i shimmed an oil pressure regulator for about 110psi

the 12A needs all of those parts to be reliable @9000rpm, but since 1980 Mazda has updated the 13B, so the S4 engines got a bigger oil pump, the S5 engines got the hardened gears and better tension bolts, the FD engines got all that plus the MFR bearings, the higher oil pressure and better oil pan.

so what i'm saying is the FD engine is actually built to better specs than the MFR engine from 1980. if you spend most of your time under 8500rpm, the FD engine is fine stock.

the reason I went pp, i know a guy in canada who built a PP engine for his FC, and its just a stock S5 block, with 9.7 rotors, small PP, haltech E6k, and it added 100hp and gets better mileage than the stock 6 port engine. i'm not sure how many miles it has on it, but its done probably 5 years worth of track days/sunday drives...

fidelity101

iTrader: (11)

I never knew the S5 tension bolts were better, I'm pretty sure my engine has a mix of S4 and S5 bolts because there are so many laying around in my "spare rotary parts box"

Are they hardened or what makes them better?

S5 are the ones with the "ribbing" in the middle, correct?

Shainiac

iTrader: (7)

I think the "ribbing" is what made them better. It changed harmonics on the bolts, probably to something outside the operating range. In the old Comp manual, they actually recommended globbing a large ball of silicone to the middle of each tension bolt to dampen vibrations!

rx7freak13v

So the s5 already has hardened stat gears? I didn't know that, can they use the 3 window bearings?

I'm honestly not sure what I have. My brother picked up an s5 gxl. After than 6 months of driving it, an oil seal failed and was dumping oil into the housing.

We picked up another motor and put it back on the road.

I took apart the old s5 motor and I found one s5 rotor and one s4 rotor along with one s5 housing and one s4 housing....now I'm not sure of anything. Could be mixmatched stat gears. Also any idea on how to tell the difference between s4 and s5 front counter weight?

peejay

If you resist the urge to close the ports super late, you won't NEED to rev to stratospheric RPM.

tasty danish

iTrader: (5)

WTF? English?

There really shouldn't be any special reliability issue with a PP engine. It's not like a J port that eats coolant seals. If you go Peejay style, it'll live just like any other NA rotary. If you zing the **** out of it, carbon seals if you want to rebuild it a bunch, ceramics and supporting mods if you want to twist its brains out and forget about it.

j9fd3s

iTrader: (3)

someone already took the good stuff, i've seen it a lot actually. lots of s5 engines with s4 internals floating around...

or put the 12A air cleaner on it! a longer intake manifold works too

dre's customs

iTrader: (2)

I have been running rotary's for a long time, and I never had an issue of the actual ports causing engine fatigue. The part that kills the engine, is the excessive RPM's that everyone THINKS you have to turn. I have never seen or heard of a PP or a BP causing engine damage. Its the drivers right foot lol

con-3-fc3s

Idk if the s5 gears are hardened but the ribbed bolts are better though. I just used rx8 stat gears in my s5 t2. How the build coming along?..

rx7freak13v

i have been doing alot of research on the topic and have been learning a lot. something that i cannot figure out is how are people keeping their pp quiet enough for street use? i know there's quite a few people daily driving these monsters but no one explains much about exhaust.

however i will include that i seen a dyno sheet somewhere (i can't remember now) that showed 310hp at the flywheel and 210rwhp....that's a lot of hp drop from drive train and exhaust. it seems the smallest restrictions really take a toll on a pp hp.

there's not many people that actually post dyno slips of na rotaries so really hard to find the people to ask questions to. everyone that has commented on people thinking about pp builds all talk about how it'll probably barely end up making more power than a large street port build after it's quieted down (credit more tq still though).

because of this i had shifted my plans more towards a bridge port (the autocross class i plan to participate in is open for rotary porting so it really doesn't matter which way i decide to go) i know i can quiet a bridge port down and still get get around 230 or so rwhp (by what i've read) i would be using efi itb's either route i go. i would honestly love to have a pp motor since it'll make more tq than a bridge port everywhere. i have alot of machine work to get done before i do the porting so i have some time. i still need to replace the bearings in the rotors and choose my apex seals and have the rotors clearanced. have the e shaft worked over and have the rotating assembly balanced. hopefully by then i can have a decision.

everyday i spend quite a bit of time searching trying to figure out which porting route i should go. i do know that pp are more tame than bridge ports are and i do plan to street the car. i just can't figure out how to keep it quiet and still make decent power. i spoke to a gentlemen that was making 183rwhp on his pp dd. that's not very much power at all. that number has been reached by a few people on stock ports.

give me some more input guys. power goal is 250rwhp but if i fall short down to 230rwhp i still won't mind. i would probably be okay with 220rwhp (note these power numbers are after it's quieted for street/track use. it needs to be under 100 dbs, which i know is hard but has been done)

fidelity101

iTrader: (11)

s5 stat gears are hardened.

peejay

12-pin rotor gears ('86-up) are also orders of magnitude lighter in gear loading relative to the 9-pin (-'85) gears.

Mazda did a paper on the gear loading and showed that the 9-pin rotor gear's load curve basically turns into a vertical line at around 8000rpm, the 12-pin gear stays relatively flat with no big spike, at least not in the tested RPM range.

One more reason why FC rotors are better than the older stuff.

I haven't had a problem yet with running non-S5 stat gears at higher RPM, using 12-pin rotors.

j9fd3s

iTrader: (3)

the exhaust isn't really any different on a PP or any other port. the last track day i did, was cloudy, so me and my friend with a stock port FC both got flagged for sound @105db. we are both running basically the same exhaust, difference in noise is zero. oddly on a clear day, they are both under the 103DB sound limit.

i don't have the sound thing totally figured out, but i'd stay away from borla's, it isn't quiet to begin with, and i think mine is dying.

dyiman25 posted an engine and chassis dyno, the T2 drivetrain takes 80hp@9000rpm. that is almost a 33% loss! the gearing is horrible too. him, and my other friend with a PP FC have broken a few of them, so i would skip the turbo trans, it does not seem to work in a road racing NA engine environment very well.

i am actually expecting to do about 210-225 rwhp with my 12A PP, which is around 260flywheel, a 13B should easily exceed the 230rwhp mark

doing a bridgeport won't really help, it still needs a free flowing exhaust, and it still needs a lot of RPM to make power, so drivetrain loss is still gonna be big with the turbo trans.

rx7freak13v

wow! that's probably the best news i've been told in a while. and the stay away from borla, i was planning to pick up 2 of their race mufflers, so again thanks.

so if a t2 transmission that has been proven to withstand 500rwhp on a boosted motor can't handle what us NA guys throw at them, then what is the alternative. i was planning to pick up a turbo transmission and really can't afford a racing gear box. i had thought about the supra transmission because i know someone makes an adapter plate. but i don't know anything about supra transmissions and not sure what model supra transmissions people use and whether it's na or turbo or if they're the same?

i do know that my stock port motor has destroyed waaaay too many na transmissions and is not an option. any idea on which transmission will be the best on a low budget? i have to decide on the trans and order a scatter shield for it and then i can figure out clutch and etc.

so you're saying that a bridge port and pp are going to ultimately end with the same result as far as sound but the pp will make more power and tq and of course be more drivable...?

any idea how long the epoxy on the pp intake runners will hold up before it starts leaking water into the housings? that my biggest question on pp life span. some people has told me 20k miles and others claim to still be dd them after 8 years. i hate getting mixed results like that lol.

some things you just don't find answers to until you ask a question. searching alone isn't enough when it comes to na rotaries. thanks guys

Acroy

iTrader: (3)

I don't have a lot of experience on rotary exhausts (mine have all been RB). However, myself and friends have had very good luck quieting piston engines with cheapo glasspack straight-through mufflers. They have little or no backpressure, available in sizes up to at least 3"ID, and dirt cheap. One fellow with a built 355 Chevy for drag racing (something like 600hp at 8500rpm) managed to make it very quiet with 4 total glasspacks, 2 in series on each side. I would suggest at least looking at these, nothing to loose especially with a build on a budget!

rx7freak13v

unfortunately it's been proven that glass pack style mufflers can't handle the heat of rotary exhaust and burn out within hours of driving on them lol. thanks for the response though.

any experience with magneflow hushpower series mufflers they claim to flow better than a straight pipe and guarantee to lower exhaust db's. but i haven't really heard much about them with use with rotary engines.

23Racer

I can add a few things to this that may be of help. On my car I have been running the same NA box for about 6 years. I never side step the clutch from a start and I granny shift the thing. It has at least 5 3-Hour races on it and a number of 20 minute races and lapping days. I have only been making in the 180 to 200 rwhp range, but with some care and lots of oil changes, the boxes can be made to live on a race car.

Where any street box has an issue is in the high rpm shifting area. A number of boxes will handle the torque, but the synchro's can't handle the shifting above 9,000 rpm. When I try to shift at that RPM, all I get is grinding. I now shift slower and let the rpm come down to make the shift better. This will be the same issue with all street boxes. The main issue with the TII box are the gear spacings. I would look at the Quaife replacement gearset for the stock NA (I believe) case if I was building from new. They are fully strong enough to handle the loads and everything else, like driveshafts, shifters, clutches and starters are all stock and bolt on.

http://www.quaife.co.uk/shop/products/qke4k

Regarding mufflers, I have had a race Borla on my car for over 10 years. It works great and it is still as loud as it always was, LOL. I add a Super Trapp on after the Borla when I want to be Street quiet.

Eric