shainiac

Here is my thread involving the sleeve method:

Modular Timing P-Port design idea - Nopistons Mazda RX7, RX-7, RX8, RX-8 Forums!



I haven't had time to work on it other than throwing together drawings in SolidWorks.

I just found out that the machine shop manager for my school has two ITS RX7s, so looks like I might be able to persuade him to let me play some time soon.

I just bought some S5 NA rotors and a few junk housings to start doing prototypes, but its unlikely that it'll be running till summer as I need a new daily driver if the RX is going to be torn apart.

PDF

My daily driver work van has had a 12A PP in for the last 4 or 5 years, it gets driven everywhere. The engines on it's last legs now though, it's done about 43k miles and doesn't really want to hot start anymore. I'm going to replace it with a stock 13B 6 port so I can tow my boat.

rwd-pog

Its interesting how many people use pp engine daily and cover high milage. And then you hear so many people saying you cannot use a pp on the road and they only last about 2000 miles. Normally the people who say you can't use them on the road don't seem to have ever had one and are just repeating what they have heard others say. I'v built my own 13bpp engine but i have only ran it very breifly as a test so i have no expierence of using it on the street or how long it will last. As mentioned before though it is extremly loud(no exhaust when test started) it was unbearable even with full ear defenders on.

Maxt

The biggest issue is the exhaust, since backpressure kills power far more on P-port than Sideport engine. There isn't to many ways to kill noise without added backpressure. I recently bought a book that shows how to engineer the sound waves to knock each other out by constructing the muffler in a certain manner. The problem is , is the size of the muffler may be tight to fit underneath any rx7.

It is pretty tough to put together a system that maximizes power without being an ear breaker. Really the p-port needs a megaphone style collector with little noise baffling, and thats not going to fly on the street.

But as far as the engine life is concerned, it turned out to be nothing but the usual BS from the forum big mouths who don't even have the experience to talk on the issue. In reality the p-port is probably one of the best designs since the crankcase side of the side seal is never subjected to wet fuel charge. The only problem lies with making sure the bearings and oiling system are put together properly. The rotary has pretty big bearings so the speed the bearings see per shaft revolution are pretty high, which means in a nutshell, it needs clean fresh oil to last. Other than , they are tough as nails.

j9fd3s

this thread got me off my *** to go play with mine somemore (its cold!)



i put a bunch of gaskets to "fix" my warped collector (note, 1/4" flange + PP engine = warped flange, and happy motor), made it a bunch quieter, with the RB 3" presilencer shoved in the tailpipe its quite nicely quiet. mine goes, header collector, 3" glasspack to 3" borla, which is loud adding the RB muffler cuts the high end off, and its actually almost nice.



since its not 100's of DB now, i took it around the block a few times. my CARB is jetted just like mazda says to jet it in the competition manual. since that's the motor i have, i've decided i need to play with the exhaust until the carb works right.



anyways, the RB muffler comes off to drive it, so its still loud. drivability is ok, the plugs are kinda done from all the no load idling it gets. it wants to buck if you're not accelerating or decelerating...



i made progress today, exciting!

rwd-pog

Its promising to hear a lot of feedback from people who actually have tried making peripheral port engines and have expierence of how they work. My main question now is does the exhaust need to be so free flowing to quickly get rid of the exhaust gases before they get draged into the next induction stroke and weaken the mixture or is it another reason?



Thanks for all the replys's and also if anyone is interested in this kind of thing have you ever seen the TISC system, it gives a 17% increase in torque at 1500rpm and 13% at 3000 rpm.

j9fd3s

exhaust is KEY.



mine is too restrictive!



my next task is to redo it so it flows better, and hopefully is quieter too

TYSON

That video is 3.5" exhaust. There's 2 Magnaflow mufflers in line, but it got noticeably louder after the first dyno session, so I'm pretty sure at least one of them is completely burnt out.

j9fd3s

its amazing how much exhaust energy there is, especially at idle.



mine blows rags around the shop, and the bushes 10+ feet away

TYSON

yeah you could feel the breeze from mine back about 15 feet. When I backed it out of there the first time with the open header it cleared 1/2" gravel off a spot 10 inches wide and 3 feet long under the car