mperformance

Hi,

I'm building a low 14s 12a n/a streetable streetport in a FB chasis with 4.44 gears.

I currently have the following problem which I need your input.

The last engine spun the rear rotor bearing due to low oil pressure (old pump used) and overreving it.
I managed to run consistent 15 flats with a weird porting scheme which should not be that great. I had huge and I mean huge exhaust ports, the ones recommended for a radical bridge port without the exhaust sleeves with intake ports being basically the mildly ported intake ports without the bridge copied from a bridge port template.

When the engine bearing spun the rotor basically hit the rotor housing slightly so I'm redoing the exhaust ports since I'm using untouched housings. Now I'm thinking about using the exhaust sleeves and doing a normal exhaust port to keep the velocity high enough and keep low end torque. But I'm concerned, maybe the huge exhaust ports did help.

I measured the old ported intake ports and they were 50mm from the bottom to the top opening, I read elsewhere that 53mm is considered a mild port and 58mm an extended one. So basically I did the ports too small the last time.

Mind you the car ran consistent flat 15s and now I want to go low 14s. I want the biggest intake port possible and keep it streetable and keep the exhaust matching the proper size. What would be your suggestion? keep the exhaust sleeves and port normally the exhaust, not too wide and keep moving up matching the sleeves. Intake port it more agressive up to 56-58mm?

Help me out I just received all the goodies to do the engine, but want to see if it's possible to improve performance close to a whole second.

Rotary7s

big is not always better.

My friend ran 12.6 all motor in a bridge ported 12A in a first gen.

I finally got to see his ports,the exhaust port was NOT much bigger than stock.
The bottom of it was to the sleeve,and the top was kinda squared off.

mperformance

BTW I just got a mazdatrix heat treated oil pump to avoid the same issues.

This time I'm using solid corner seals and (pacman) springs.

The car will be dyno tuned after engine goes in. I want to make as much power as possible with it, but keep it streetable. By that I mean able to run the muffler I'm currently using a huge SP Greedy with mindtrain header with 2.5" piping

mperformance

yeah that's what I'm afraid I will found out with this new properly built engine...old engine ran like a champ just never got to be able to hit mid 14s with it. I never did dyno it though, with this one I want to do all that's available without adding a power adder nor compromising streetability.

Any pictures of a 180rwhp streetport 12a?
I'm happy with 180 for the street/track right now.

mperformance

well I'm almost done with the cleaning and I'm getting ready to close this engine.

Here are some parts I just got. I'll take more today of the actual porting and the car.

diabolical1

iTrader: (3)

yum! yum! it's always good to see parts ... yes, please snap some pics of the motor before you assemble it.

take some shots of your exhaust ports especially. keep the sleeves, but block the holes.

inuissus_cendi

mod your oil pressure regulator for higher pressures too. just tap the end with a hammer basically, theres a thread about it somewhere.

mperformance

Yeap I'm going to push the oil pressure up to 110psi for this one. Now with the new pump it shouldn't be a problem.

Here is the difference in porting. These are already ported but I'm extending it about 3mm more. Big difference once I'm done.

Intake:

mperformance

here is the exhaust port redone

mperformance

funny thing is that the car ran fine with the mega port, it had a little bit of a loppy idle, kind of like a brap brap but very muted. Car had increadible milage on the open road, and had a bunch of torque, I kind of liked this combo. Small intake ports and huge exhaust, only problem is that it just didn't have enough power for my current goal.

So I'll sacrifice that huge porting for something more proven.

If anybody has any recommendations let me know, before I close this one up...

will make the 180whp?