Over on the other forum, Adrian (Hyper4mance2K) just did 189.65 WHP from a 6-port 13B with smoothed ports but stock port timing. Not too shabby. He said his timing was 26 degrees BTDC at full advance. Not sure what the split was. I know a lot of NA guys like to run zero split.

Is there a write up anywhere about how to modify the dizzy?

What mods are you looking to do?

well im kinda stuck between running the dizzy and the FC CAS. I have both and i can utilize both, im just not sure which route i want to go. Having the ability to play with the timing would probably not be a bad thing, but would be another issue in tuning.

i think im going to opt for the dizzy, cut the slots a bit to bring the split in and only use the vac advance on the leading. Then run an array of MSD boxes (especially because ill need an output signal for the MS to read off of).

I was running about 26 BTDC on my stock port FC, made about 161 whp @ 7500 rpm. The car really started taking off north of 5500 rpm.

I think at one point in my timing curve I was at zero or negative split, forgot which.

K&N Drop-In
Rtek
Racing Beat Header, Pre-Silencer, Catback.

Took the same ECU to another FC, but with a weak compression motor. Exhaust was changed to an RB True Dual. Made 140 whp @ 6500 rpm. Power was lost most likely solely due to the motor being weak. Power just dropped off like a cliff after 6500 rpm. None of that taking off feeling was felt on this motor.

My guess for a good recipe for a high powered NA.

Cone filter getting ambient air.
Ported or Aftermarket Throttle Bodies
Intake Manifold with straight shot runners, Port-Matched, Extrude Honed, then Ceramic Coated
ECU that adjusts both fuel and timing
Making sure you have enough fuel with an aftermarket fuel pump and 4 x 720 cc's. If you have an ECU that can compensate for that much fuel at idle, no reason not to go bigger.
Large, Aggressive Streetport on a freshly rebuilt engine, with good dynamic compression. Get even crazier by re-balancing the rotating assembly and using lighter rotors to spin the engine even faster, with a matched intake manifold
Ceramic Coated Headers, with Header wrap
Expansion Chamber Collector
Pre-silencer and dual mufflers if you care about noise or straight pipe and single muffler if you don't care

As an anecdote, when I bought my latest FC, it's aux ports were frozen open. Thing was such a mule in the low end, you really had to step on it for it to go anywhere. I will never forget that feeling, since all my other FC's had working aux ports. I was like WTF????

i would have to say that four 720cc injectors is far far more fuel than any streetport engine will ever need. Same probably goes for 1/2 bridge. The stock 460 injectors are more than the engine needs from what i have found. Or at least while running an MS. I have noticed that the stock ecu control over the injectors limited the injectors pulse width considerably.


On a side note, im hoping to have my stock port s4 13b up and running in the next week or two. Hope to be good enough to dyno before i leave in late April.

4 x 460 cc will run out of fuel at about 195 - 197 whp.

4 x 550 cc will net you more than that, but if you're shooting for big power, at least go 2 x 550, 2 x 720 or 4 x 720 if you're going to be replacing injectors.

true, but with a stockport 460s are plenty. Logan is the only person i know of making anything considerable on a streetport @ 230hp. bridges i rule out since there are far more factors (like rpm) to contend with. I am probably just going to use the four 460 injectors i have currently with my setup. Mostly because for the stock port i think that is all ill need and i dont have any funds budget towards injectors replacements.

Yea, you should be fine on stock ports.

Hope you get over 180!

would be nice! I would be happy with 170.

I never dynoed at a real dyno, but I did not notice or measure with my G-tech any difference between 13.5:1 and 12.8:1 AFR at 7,000 rpm. My power actually dropped off below 12.8:1.

I don't know if the 197 Whp number is correct on 4X460cc/min

Thermal energy of gasoline: 124,000 btu/gal

Injectors = 4 X 0.46l/min = 1.84 l/min X 80% utilization = 1.47 l/min = 88.3 l/hour = 23.37gal/hr.

You put in 124,000 X 23.37 = 2897270 btus/hr = 1138 hp! At an 85% drivetrain efficiency, (227 at the flywheel), This implies that the engine is < 20% efficient!

Lets go from the airflow side. 4 X 0.46 X 80% = 1.47 l/min = At 740g/l this gives 1.09 kg/min or 18.2 g/s. At a 12.8:1 AFR this requires 232 g/s of air or 1.025 X 232 = 238 l/s (edit: at sea level, 70 F)
Because the rotary displaces 1.3 l /rev, this equates to 11,000 rpm at 100% VE.

I don't know if there are more complicated methods at work here, but the way I slice it, 460 cc injectors are PLENTY.

I can also say that my '86 would run 12.8 AFR up to 5,500 rpm on a single set of injectors (no staging until that point). It would also do a 14.8 quarter at 105 mph (it was not that slow/starved for air).

I was using peak and hold on the Haltech.

Try your calculations for 4 x 550 cc's.

I forget what the hp number is, but most people recommend upgrading the injectors to 720 cc after a certain whp for turbo cars. Ballpark 300 whp. What's the efficiency ratio there? (for 300 whp and 4 x 550 cc)

Nice calculator for injector sizing:
http://www.rceng.com/technical.aspx

Bear in mind that turbo fuel requirements / per horsepower are considerably higher than NA requirements.

Unless designed very carefully, a turbocharged engine is less efficient than a naturally aspirated engine.

300 whp looks like about 25% efficient with 4X550s (this is a little high for a stock turbo configuration) I would be worried with 4x550s at 300whp on boost.