I know this has been done. My question is:
I would imagine that when running a Pport that you would need a huge turbo. The lag would be terrible im sure. But could you make a setup that doesent choke the exhaust flow but still have good boost by 4000?

 

well a PP hauls from 5000 to 10000 rpm, They normally idle at around 2200-2500rpm, if you got a turbo to spool at 5000rpm where its power normally picks up it would go insane, talk to the likes of RICE RACING or CRISPEED, they have played with PPT's

 

A partial periphial port would be better for a street car

 

Ok. I hate to sound stupid, but what is a partial PP? Is a big bridge with relieved housings or something else like a 4 port with peripheral secondarys or something? The PP I drove came on hard around 6k so I couldn't imagine what it would do with a turbo coming on too. A PP almost feels like a turbo it comes alive so hard and so abruptly. It just does it at the same RPM everytime.
Don.

 

A Partial periphial port is when you keep the stock location side ports open and machine a hole into the actual rotor housing for additional air to be coonsumed be the engine. When you do this you must fabricate same diamater tubing as the machined hole onto the intake manifold. The gasket holes can be cut out to match the machined holes. A friend of mine is building the partial periphial ported engine with steet porting on a REW motor as we speak. I will get some pictures of the work tomorrow. I screwed up some of my rotor housings so am thinking about doing another full periphial port on my race engine or a partial periphial port with a bridge to see how that combination works.

 

Would a Partial PPort help get some power under 5k?
Like a nice hefty streetport and a secondary PPort.
Or another combination?

 

Greg,
Do you use any kind of butterfly or anything to close off the PP when the engine is at low RPM? That would be the best of both worlds... Stock port low end grunt, and PP POWER!!!! I always love driving a PP.
Don.

 

That would be a GREAT idea but a Huge pain in the *** to build.

 

So if the PP is always open then you lose the low end torque of the side ports due the the long duration of the PP. Correct? Is this just being built for a huge port area so it can flow like crazy up top?
Thanks,
Don.

 

PP's sound pretty sweet! Anyone have more info on them?

 

port area isn't as important as port timing and port flow IMO. you can have small port area and still make killer HP.

P-ports are great because of the port timing and they are a straight-shot into the rotor housing. You can make a monster bridge engine that makes more HP, but at that point what you basically have is two p-ports that start out at the "normal" intake ports and then go in thru the rotor housing. Better to just go to a p-port in that case because then you don't have to compromise the cooling system.

Many/most race sanctioning bodies define a peripheral port as when any amount of the intake goes through the peripheral housing... by that definition, even a relieved bridge port is illegal (where p-ports are illegal) because of the reliefs cut into the rotor housing.

 

Im working on pretty much that with my 12A that Im building. Big bridge, partial PP, and I plan on having it in 3 stages. Just the center ports open below 3500-4K, then the bridged outside ports open up, then the PP opening at 6K or so. I know this wont be easy, but I have faith that I can do it with my resources. And once I am familiar with the tuning, and save up enough for the turbos, Im turboing it. And that engine will be going in my caged 84 GSL

 

The main reason PP motors aren't very streetable is due to their high idle and lack of low end power right? Well isn't this caused by the massive overlap from the PP, like a piston motor with an extremely high durration cam. Therefore shouldn't a partial PP motor with a smaller PP have less overlap (probably less than most BP motors) and be quite streetable:1party: Just a thought.

 

so what inlet port timing do you use on a pp turbo engine, is it the same as for an NA engine (eg MFR housings IO 86° BTDC
IC 75° ABDC - yawpower figures), or is it later on both opening and closing. Are the ports the same sort of size and shape (some NA pp's are either D, O or rectaungular shaped).
In another similar thread about a partial pp, the primaries were retained but the ports in the end plates were ditched, and the p ports were only 40mm, so does it really give that much more power than a side port?
final Q; in the thread with the "glued" manifold that was modified for partial pp's as well as retaining all the side ports, it was dividing the secondaries on the inlet manifold to also feed the partial pports, so the single tract was feeding two ports. The inlet tract did not appear to be enlarged. Wouldn't the act of taking a nice, tapering inlet then suddenly expanding it into two paths actually be detrimental to air flow (velocity, etc). And as it is not actually flowing more air through the inlet manifold (just splitting what it already has) would it really do anything to increase performance?

 

hmmm....
some very good points, i'm interested in the answers ....

 

On the partial pp manifold, all the stock intake ports were kept, and given a large street port. They were not glued shut, the pp were less than 40mm also so that the stock manifold could be used. This technique has been done before and proven to obtain ridiculous amounts of horsepower...More info coming soon...

 

Here is a picture of what the rotor housing looks like from the inside with a partial pariphial port. You can get a good idea on the prt timing from this picture. This combination made 700+ hp with a T51 HKS turbo

 

greg....you should know that geocities wont link or show their pics
just give us the link to copy and paste

 

here

 

hmmm, that is a fairly small p-port isn't it, and late opening too...

I agree that getting lots of air in to the engine is the path to big power, so on a partial p-port and 4 port arrangement there must be a significant amount of air provided to the ports, hence just re-routing the air from the standard manifold would not be sufficient to fed the beast to realise the potential power the ports could give.
(bear with me here...)
The analogy I am thinking of is when you fill a coke bottle with water and stick a garden hose in it, then turn it up-side down... the water pours down the 10 or 12mm hole in the hose and it takes say 10 sec to empty. The act of splitting that 12mm pipe into 2 12mm pipes about a foot down the hose doesnt mean that the bottle will now empty in 5 seconds because there are two outlets.... it should still take 10 secs, but the pressure in the split hoses will be less (about half I'd say... )

So assuming my garden physics holds true, then inlets need to be seriously revised if not replaced outright to realise the power potential - and the glued up inlet manifold with the 4 ports and the small pp's as well might not really deliver anything special.

 

Greg, does hector or anyone else have any dyno figures for a combi-port motor using hector's manifold, or a similarly modified stock manifold?

 

How long would a partial P-port rotary last? Especially a turbo one!
I heard the a full p-port rotary doesn't last too long (6-12 months)

 

I will have some dyno numbers up soon, but as for old dyno sheets... I'll have to find out...

 

What kind of internal engine mods have to be done to allow it to spin that fast?

 

I think PP's last longer than bridgeys. The intake port is similar to the exhaust port and stresses the apex seal the same. There is no thin metal bridge to crack, and the water jacket seals aren't compromised. Like everything else.. it depends on how you run them. My old roomates ran for a couple years and around 30k mi or so, and he sold the car... running strong. The engine has been put into another car.
Don.