| SaabKraft |
hey hey. after selling my little FB, i've been toying with the idea of picking up a 2nd gen sometime this spring/summer. while the Turbo 2 is the obvious choice, i was wondering if anyone's built up or knows someone who's gone the normally aspirated route in modifying the 13B engine.
i was thinking of something with a 5 digit redline (?). probably an intake, bridge port (with upgraded seals), exhaust, fuel supply modification/stand alone EFI/spark control, uprated oil coolers, aluminum flywheel, etc.
it'd probably idle around 1500-2000 rpm. i know a Turbo 2 is the easier way to power and torque, but i'd like to try something with a different feel to it (linear power delivery that just keeps winding up). Steetability is taken into consideration, but it's not a priority.
I suppose i should talk to conroy about this. i'm not sure if i'd end up with a 10000/11000 rpm redline (as fun as it'd be), but i'd like to explore the costs/performance of a non-boosted 13B.
any thoughts/contacts/feedback appreciated. |
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| red88.n/a.rx |
I want to do the same thing but go all motor.... im not interested in a turbo yet... I want just a nice bridgeport with high flowing exhaust to put down about 250whp....
With the stuff you mentioned youd be lucky to build a reliable motor for under $15000 if you went the turbo route. Im very interested in doing something like this aswell.... If your interested I have a motor thats runs well that could be used for a bridgeport and Ill let it go for $500... let me know. |
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| SaabKraft |
[QUOTE]Originally posted by red88.n/a.rx
I want to do the same thing but go all motor....
uh... there is no but. we both want to do the same thing. i acknowledged that turbo II's are the obvious choice, but i want a high high RPM all motor. |
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| now |
I will be building a high compression P. Port motor
over the winter but i dont think you would want to part
with the money this thing will cost.
mazda racing factory P port housings are about 3000 canadian
each + all the rest of the parts to make it go:)
later
matt |
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| edmrx7 |
I don't think you can build a streetable, reliable motor that runs 10-11000 rpm. You will end up rebuilding at least once or twice during a season.
If you want to do something like this, you had also better be prepared to build it yourself. Getting someone else to build it repeatedly is going to get expensive, and they certainly arn't going to offer any kind of warranty on it.
Richard. |
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| SaabKraft |
quote:
Originally posted by edmrx7
I don't think you can build a streetable, reliable motor that runs 10-11000 rpm. You will end up rebuilding at least once or twice during a season.
i wouldn't expect it to last particularily long at that levels. the 5 digit redline is likely the top-end of the racing normally aspirated rotaries. it's appealing in a very basic sense, but pretty impractical.
i'm also not too sure with how big of a perfomance gain porting gives to the rotary, in terms of increases. would an agressive street port and some bolt ons bring it to around 190 hp? i've read some sights that say porting starts off at a 10-20 hp increase and goes up from there (with the appropriate supporting modifications). They were talking about non-boosted engines too.
My general impression is that porting agressively opens up the mid to top end power more, but in turn you begin to lose lower end torque the larger the port job. Which seems detrimental to acceleration from a standstill, but once at speed, very responsive and powerful. |
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| ehrgeiz |
I was digging around RX7 Club and it seems that quite a few of the guys racing PP 13B's are near or breaking 300whp. They're also getting decent (relatively) milage out of the engines (3-4 full race seasons). Also I believe RB makes a rip off of the factory P-ports for considerably less bling.
I think the excessive noise would probably be the worst thing about driving one of the street. Though I bet it would last longer than a pushed bridge port. |
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| SilviaDrifter |
max in calgary can help u
he is almost his P.Port daily driver |
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| red88.n/a.rx |
| well you didnt get the point really... but I know because I had a ported rx7 and it way too loud.... A bridgeport is quite a bit louder and more obvious. When I say I want to build one I plan on driving only the weekends not as a daily driver, you couldnt afford the gas to keep it going. |
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| SaabKraft |
quote:
Originally posted by red88.n/a.rx
well you didnt get the point really... but I know because I had a ported rx7 and it way too loud.... A bridgeport is quite a bit louder and more obvious. When I say I want to build one I plan on driving only the weekends not as a daily driver, you couldnt afford the gas to keep it going.
ah. it's just that you said you wanted to do the same thing, but not go the turbo route, and then mentioned turbos again as if it's what i wanted to do.
i'm aware it'd be stupidly loud, and it'd not be a daily driver. probably weekends and some evenings, like a cell phone plan (heh).
until i'm paying mortgage or rent, the cost of gas doesn't matter too much to me.
:lol:
would a P-port even be street legal or insurable (in regards to noise / degree modification?) |
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| 4kruzn |
any one who seriously wants a daily driver where the torque peak is at 7-8000 rpm should come out and go for a drive in one first. really guys give your heads a shake.....
a periferal port is a extreeme RACE engine. oh sure you Can drive it on the steet but you wont like it.....
if you want na and high horse power a NA 20b is the way. i could get you one for about 5g's. seems like alot but probly its just as cheap as a big properly built PP.
Dont be fooled by people telling you that an engine that makes no power till 3500 and starts to turn on at 55-6000 and then pulls hard from 7-10000 is a street motor, they are really bullshitting you. you would need mid 5 sreies gears in the rear end just so you could use second gear in town. the car wont pull down the hyway cause with stock gears it turns 3000 rpm and will bogg out and fowl up and most hyundi's will be faster than you. oh oh oh ya and also you will need a mazda race gear set cause the factory trans will blow up within a week or two cause they just cant hold together at 10000rpm shifts. just my little rant for the day....
PS. i have a set of MFR, "manufacturer Race" PP housings from a 12a factory sponcered race rx7 for sale. these produced 260 hp at around 8500 rpm. these sell for around 1800.00 us each new and i will sell them for 1500cdn for the pair. like new. used only for 6 hrs at sebring. pss. i will throw in two 12a cores for internal parts for you also at no additional cost.
i'm done now. by. |
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| SaabKraft |
a normally aspirated 20b, eh? that's a 3 rotor, correct?
some super-brief googling says 20b's were production engines for the cosmo, but were twin turbo and usually mated to a 4 speed automatic. i like the torque numbers, though.
is that motor a direct retrofit into a FC3S bay and tranmission? or will custom fabrication need to be done to mount it up?
also, some numbers on a stock NA 20b would be helpful. |
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| SilviaDrifter |
umm it wud fit in a FC........i know the TT's need some fabbing to fit im not to sure if the NAs are the same.....doesnt hurt to do more research
go to www.Rx7club.com and they have a 20B specific forum go check it out
to be exact this is it
http://www.rx7club.com/forumdisplay.php?f=95 |
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| now |
na 20b in a fc would be easy!
matt |
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| SilviaDrifter |
| matt how hard was it to fit the 20BTT in ur FC?? |
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| red88.n/a.rx |
quote:
Originally posted by now
na 20b in a fc would be easy!
matt
Would You install a 20b in an fc if the price was right? |
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| now |
sorry I don't have the time.
When I say easy I am comparing it to the 20b turbo install
which was far from easy so I guess na 20b install would be better
to say easier :)
matt |
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| SaabKraft |
| did you go stand alone fuel management for the 20B? |
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| Al36rx7 |
And to add a comment about 13b eccentric shafts....They start to flex at about 9500. Too much more than that will result in the engine not running very long.
It cost a bunch of cash to spin to 10k reliably!!!
Dave Lemon of Mazdatrix builds a streetport 13b that spins in the 10k area....but he rebuilds the motor on a very regular basis. I've heard it's in the area of every second of third race weekend. That amounts to about somewhere around 6 to 12 hours. But for that time you have a very peaky engine that doesn't do squat below 7000.
Listen to Kruzin' Guy....I think he knows what he's talking about!! (somedays!!...Hah) |
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| KKMCanada |
This is an old thread, but thought that I would add to it, and clear up some of the falicies on driving a 2 rotor p-port on the street.
I built an s5 based P-port with efi in a fc GX. I used a TII transmission with os giken twin plate, with a conversion driveshaft. The car was stock s4 n/a with about 198k km's on the clock, it smoked a little, had a catback and ran a best of 16.3 something at Race city, pretty typical of a stock n/a FC.
I used the original mazda sports kit p-port size and port timing, along with their intake length , basically the same specs as the early Mazda and JUN GT cars. I started with a homebuilt street header, but recently switched to another homebuilt header that is equal length and much different dimensions than a street header. Its a mazda oem 2mm /9.7: motor with a few minor oiling mods to keep it alive..
The realities are , with a 4" single exhaust system and the tuned header, its ear splitting.. It wasnt half bad with a dynomax catback on it, but it did hold the motor back past 8000 rpm. I think the happy compromise is going to be 4" resonator added to the mid pipe. With a regular catback the intake noise is louder than the exhaust.
The killer thing is, is how driveable it really is. It will idle as low as 600 rpm when its warmed up. Its happiest place is right around 1300 rpm. In that sense its more docile than a bridge or even a half bridge. It doesnt drop idle with load like a big ported side port engine. I can turn on all the loads in the car, and it might drop it 25 on the haltech with no idle control active. It puts a stock N/a motor to shame at any rpm. I can take a hill in 5th at 2800 rpm without shifting, that my stock n/a wouldnt..
Yes peripheral ports make peak power at higher rpms, but the bottom end being dead is not correct, they also make more power through the entire range than any other style of porting I have encountered so far.. It is indeed very easy to drive even with the twin plate clutch. Throttle response is sharp and crisp from any rpm.
The next mind blower has been the fuel mileage, its really not that bad, in fact my highway mileage is higher with this motor than it was as a stock s4, it loves 87 octane.
It needs some more fine tuning, as it sits now, but it pulls pretty clean to 10k in every gear after a 200 km break in, its very picky about a/f's with .5 either way of certain a/f makes a noticeable difference in the power, same with timing. The motor starts immedialtly usually on the first full rotation.
Once I tame the noise a little more, its going to be fine to drive on the street, as well as the track.. Next is some header wrap, some dyno tuning, and ram intake from the front of the car. |
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