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PP timing and sizing

Old 02-03-11, 10:45 PM
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PP timing and sizing

Ok, I know this is a very open ended question, but I plan on building a Peripheral Port engine for road racing in the future with a max RPM of about 9000 or 9500, and i plan on it being fuel injected if that makes a differance. so my question is what recomendations can you guys make for the optimal port timing and size? also i was looking at the weber website and saw that they make a 62mm throttle body, would this even be useable with the 13B's 80mm housings or would that just be overkill compared to using a 50mm throttle body?

side question how complicated is it to build a +10000 RPM engine? is it all down to just the clearances or is there more to it?

any help you guys can give would be appreciated
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Old 02-04-11, 09:40 AM
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It gets expensive once you start talking five digits. Don't listen to the drag racers, there is a huge difference between making an engine live for a few seconds and putting together something that will have to run for many minutes at those levels.

A powerband up to about 9000-9500 sounds very much like the MFR housings.
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Old 02-04-11, 11:48 AM
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the tread is in the NA section, but the guy started with 43MM ports and went back later and machined em to 45MM. so having enough meat to do that sounds like a great idea!

i'll second the drag racer comment, IF they run the whole season, its less run time than your warm up session.

building the engine. depends on the block you start with, over the years they have made the competition specs = the stock ones. so mazda added the hardened gears, and the side clearance on the rotors, etc etc.

mine is a 12A so i had to buy the hardened stat gears, and oil pump and stuff. carbon apex seals. i also had it balanced

i also bought the competition oil pan ($100! cheap!), and the baffle plate. oil pressure goes to FD spec.

mine isn't a serious race engine, so i think i'm good as long as i can keep water and oil temps in range
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Old 02-05-11, 02:36 PM
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I'm not just thinking of total run time... things like the cooling system and oil system can be left pretty much stock for a drag car since the load is only applied for a few moments.

I'm still waiting for the day when people start rock-blocking the rotor housings. (Filling the cooling passages with epoxy) Heck, they may have done that already and I just never noticed It's supposed to be worth 5-10% horsepower gain in piston engines from reduced deflection of various parts.

It makes dowel-pinning N/A engines start to make sense, you know?
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Old 02-05-11, 03:30 PM
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Originally Posted by peejay View Post
I'm not just thinking of total run time... things like the cooling system and oil system can be left pretty much stock for a drag car since the load is only applied for a few moments.

I'm still waiting for the day when people start rock-blocking the rotor housings. (Filling the cooling passages with epoxy) Heck, they may have done that already and I just never noticed It's supposed to be worth 5-10% horsepower gain in piston engines from reduced deflection of various parts.

It makes dowel-pinning N/A engines start to make sense, you know?
if you look hard at the 787B engine, it looks like the rotor housings are a little beefier by the spark plugs, and they do have a top and bottom plate
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Old 02-07-11, 11:02 AM
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had mine out at the track yesterday, its FUN. i want to DD it now...

so anyways, heat management is important! even on a nice mid 60's temp day, the first lap, it just MOVES. lap 2, its just ok. my radiator is suspect, so it was getting warm.

the second thing it did was turn the nicely painted RB header WHITE, and it blistered the paint halfway down the rest of the exhaust, in about 4 laps. AFR's are in the mid 11's, i was shifting about 6000-6500

it NEEDS to have some kind of cold air intake. it also might need an SS header, AND some heat shields.

but its FUN!

oh and wear ear plugs under the helmet
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