I have read that peripheral ported engines (I assume this means inlet since the exhaust is PPed already, arent any good for street use. Could anyone tell me why? would a reed valve like on the old 2 stokes help?
From reading about PPS - and driving a half BP and assuming similiar but amplified characteristics; BIG overlap, bad (no, BAD) economy, nasty off load driving characteristics (bucking about on cruise etc), on/off power delivery in some cases - and not much going on below a lot of RPM.
Lots of aussies run PPs (esp N/As), but I dont think the UK has any county with enuff roads/driving conditions of the type that would really suit a high reving PP rotor motor.
Apart from that - dont they sound THE NUTS?!
NSU RO80\'s run Peripheral ports from the factory, they idle well and they are quiet.
Yes PP can have massive overlap and huuuuuuge ports that will only be happy at stratospheric rpms but a sensibly placed and small PP can be streetable but I would hazzard a guess that it wouldn\'t make as much power as a side port without going OTT and going back to it being undrivable.
I could be way off but thats my (unconventional ?) view on the subject :)
Dont think its an unconventional view Mike, rather a view in a different context... I presumed the PP question was from a \'want power/but how bad will it be\' aspect - as why else would u go to the hassle and expense of PPs when a stock side port is so smooth? Unless due to necessity e.g. when putting together custom 3+ rotor motors when side porting is not feasable. But then why would u bother building 3+ rotors only to use titchy ports I guess!
You\'d hope that small PPs are not the way to go as Mazda has chosen to side port all its recent \'mass\' production rotors!
Rich, there is also the option a "semi-pp". full PP have their downfalls, and i also would not recomend for street use.
(http://kgparts.com/images/Intakes/semipp.jpg)
(http://kgparts.com/images/Intakes/semipp2.jpg)
also over here in Jersey the idea of a semi-pp that is not "allowed" until the secondaries come on has been toyed with. i dont have a pic at the moment but get get one of a "rough draft" manifold. the idea of it is basicly using a Dominator carb that will fow enough for this or a TBI setup with the plates being progressive. the 4 iron oem ports will be run off the primary runners and the secondary runners are ran into the semi ports. (different than the manifold pictued as the semi\'s are ran from the secondaries.) the idea of the IDA style dedicated semi runners has not gotten to far off the ground or past the designing stages at this point, but it "could" be available in the near future. :)
-Keith
Well from what ive hear if u periheral port a rotor it wont idle under 2000rpm + it wil have a very uneven idle. Ive got friend who told me about his uncles rx7 s2 with a 13b turbo with peripheral port, and whenver he pulled up to the lights everyone thought he was dragging of every light because of the high idle and uneven rpms, it would be fun for a while but would start to get annoying hehe
Hi Keith! Nice to see you here :)
Do you know of Judge (think he may be a jersey guy too?) with an RX3 drag car? I vaguely recall he has some thing like the setup u r describing? been a while since I\'ve looked at pics of the car so I honestly cant remember the exact setup...
Rich
Judge Ito ... with s half chassis (?) rx3 SP drag car. yep he\'s running semi PP, theres a few pics of it over on No Pistons and a couple of threads on ausrotary too.
It\'s true description is the "Combi Port"Which Mazda tried back in the 60\'s on carbs both for road and racing with marginal power differences.With turboing and variable port opening controlled by the throttle\'s on both turbo and N/A it is a whole new ball game.
small Peripheral ports can be quite streetable with fuel injection and a decent ECU.
Kind regards
Carl
Here are some videos of my old racecar MoTeC run PP 13B:
http://www.mymazdarotary.com/mazda_rotary/rx-4_racecar/rx-4_racecar_videos/rx-4_racecar_videos.htm
Thanks for the info.
Am I right, then in believing that I could get similar power to a bridge ported engine, if I Used PPs as \'secondary\' ports, only opening them up mat high RPM? Would a butterfly valve be OK for that or would I need something more?
QuoteOriginally posted by 20B_boy
Hi Keith! Nice to see you here :)
Do you know of Judge (think he may be a jersey guy too?) with an RX3 drag car? I vaguely recall he has some thing like the setup u r describing? been a while since I\'ve looked at pics of the car so I honestly cant remember the exact setup...
Rich
Rich, we live in the same state a few hours away from eachother, although i just shipped him some parts, i dont *know* him on a personal level. i do remeber seeing his setup before and believe it is more like the one pictured than described....
QuoteOriginally posted by Cycaduk
Thanks for the info.
Am I right, then in believing that I could get similar power to a bridge ported engine, if I Used PPs as \'secondary\' ports, only opening them up mat high RPM? Would a butterfly valve be OK for that or would I need something more?
You won\'t get as much power out of a secondary bridge port/PP as you would a true bridge port or peripheral port.
Hell - some mild ports can make more power than bridge and PP ports, a lot of it comes down to the engine builder, port timing, port shaping - especially on the exhaust port side of things, tuning etc..
You need a pretty complex intake system for a secondary PP engine. Depending on what you are going to do with it - turbo or not, a secondary bridge port becomes quite a nice street car. Secondary ports won\'t open up with a fuel injected engine until the 3000-4000rpm mark.
The manifold shown in the pictures above looks like a standard carby type manifold, Keith - you sure they aren\'t the normal water jacket holes?
they are in the wrong position to be the water jacket holes ... they would be toward the top of the manifold flange.
looks like its designed to be used with a holey type carb that has secondary throttles
Cheers Mike, yeah - hard to tell from the pics. but it is a little more clear on the turned over one (top one).
you are correct that it is a holley style flange, but a *carb* is not needed. you would run TBI such as this:
(http://www.kgparts.com/images/Intakes/web4brl.jpg)
this style (above) that is machined, instead of cast, is to replace the old style TB that has been out and proven by many people for many years. it also is a little more cost effective for the end user as a TB does not have to be purchased also. :)
(http://www.kgparts.com/images/Intakes/6inj_TB_adapter.jpg)