well i am building an engine for a road race car , its a 1988 non turbo the engine has to comply with the PRRA gt-2PR class (similar to wc-gt rules)

since its going to run E.F.I. I am not limited to running a 48mm ADI weber set up
and the only rule on porting is no Peripheral ports and i can only run turbo if the car was turbo from factory.

so i am building a 13b 4-port using a turbo engine with n/a rotors with a bridge port that does not touch the water seal.

here is my parts/work list

50mm IDA style throttle body
racing beat weber 51 intake manifold for 13bt engine
microtech lt-4 ECU
2x MSD 6al (i will be using a late model electronic distributor)
series 5 n/a rotors
carbon apex seals
racing rotor bearings
RB type 2 modified stationary gears with multi window bearings
i will use the turbo II oil pump
race oil regulator
water jacket mod
thermo-pellet bypass
maybe using the tension bolts from guru
aluminum racing pulleys
and 10lb flywheel

hmmm what else?

 

Re-think your apex seal choice, and tension bolts are overkill, just make sure to either RTV the stockers or use heat shrink. Everything else sounds good, don't for get about a good tuned header (look at yawpower.com).

~Mike...........

 

RX-8 e-shaft?? Every little bit counts...

 

The 6 port actually has more port area, so that'd probably be a better choice.

Why not go with a super light flywheel and 5.5" clutch setup for even less rotating mass? There's also lightweight rotors, 2 piece e-shafts that allow you to rev higher with little to no chance of the rotor tips hitting the side plates (if not be sure to race clearance the rotors). Why run a distrubutor if it's EFI? Why not use the stock ignition, it's better and will be fully programmable with a standalone for a better power curve? Even if you're running carbs there's advantages to having programmable ignition. There's other oil mods too, like proting the oil pump passages and smoothing them, and there's some mod to add a loop line to equalise the pressure to both rotor bearings or something like that. A dry sump can help with oiling in long, high G corners, or at least baffle the pan.

Basically you should talk to an experianced race engine builder and get some tips from them on what they'd reccomend, as most people here have never done it themselves and have just read about it.

 

Wouldn't the RX8 e shaft bearings and stat gears be better than the RB bearings and stat gears. The Rx8 parts would be much cheaper.

 

i wish i had that kind of money

 

Well he's running NA and can't run peripheral ports so I think the RX-8 stationary gears would be plenty, he could take the money he saves and put it into something else like that clutch pack mentioned.

 

as fas as apex seal choice i prefer opening a race engine every couple of races than messing up housings and rotors when a steal seal brakes

 

well, i question the distributor choice as well, but outside of that it sounds like a very solid plan.

 

nothing wrong w/ carbons N/A

 

*shrug* Locked distributor's a nice and easy solution; set the timing and go.

 

Why not use the carbon seals? Its what they are meant for......high revving N/A motors.

Your list looks pretty good to me!

 

Hmm,no PP!That sucks.

Here is a killer setup that we do here in RSA,when PP is not allowed.Its a 12A motor,and what used to be 6 port housings.

It kicks *** on all ground. Only problem is getting it running.Doesnt exactly start with a starter...

Developes 280HP at the wheels in a Midget Flat track car.

Sorry about the shitty photos.

Karis

 

^^^^
Does that Idle under 3K?

 

A locked distributor might be easy, but then you've got only one advance setting across all load and rpm points, which is very far from ideal. Why not just have the standalone control the stock ignition, that's easier than changing it all out and then a proper speed and load map can be set up for the ignition.

 

do not use carbon apex seals..

 

Judge can you elaborate. I respect your opinion, but I have seen some 12A's w/ carbons run great especially at high rpm. Obviously they are not something you would run on the street, but this seems to be a race only motor. Again just looking for a reason behind the response.

 

why not?

 

No really no,haha.But it does perform!

 

Why is this? Why are PPorts banned from most racing classes? Someone please educate me.

 

Depends on the racing class, but in general the idea is that the people making the rules are trying to equalize performance between different cars. If they know what the approximate HP/weight of everything else in the class is, they restrict things to try to get other cars be about competitive.

PPorts make a lot of power, and 7s (especially stripped ones) tend to be lighter than a lot of things... so there ya go.

 

Ouch, that is some rough port work, isn't that called a monster port though? Basically cutting a bridge port deep into the water jackets then filling in the coolant passages around it to get something as close as possable to a p-port?

I don't see why it would be so hard to start though, shouldn't it still be easier to start than a p-port? Since it is a race only car why not wire a connector up to the starter and kick it with a 24 volt battery box, that should get it spinning faster and help start it easier. Since you wouldn't be starting it every day I think the starter could handle it as long as you didn't crank the **** out of it.

 

Gotta love that good ole Mazda engineering.

 

Side PPort would like to try this with a turbo setup? Haven't heard of anyone running it with a turbo but you never know what's out there. Port was developed to get around the no PPort rule. You run the side intake and these PPorts together. Never heard one run but would sure like to. Maybe my next Frankenstein motor.

 

You can also cut the leading and trailing edge of the rotors to increase port opening and extend the closure of the ports. Although doing this requires you to rebalance the entire rotating assembly. The guys in E-prod do this to their engines, but they aren't allowed to run either a bridge or PP. I'm not sure if this would get you anything on a bridge port. The guys in the racing section might have more info on this for your application.

Cheers,

Peacedog