roundman

I need some help! Anybody know how far I can go with mods like cam and injectors with a speed density system? the car isn't street driven, so it ain't got to idle real good, just enough to get to the starting line. any suggestions or personal experiences out there[sm=smiley25.gif]????????????????

Mustang88LXKid

do you want hp numbers? or just ideas?

roundman

any information you have would be helpful, thanks

Mustang88LXKid

new cam and injectors will increase you hp. you could also convert to mass air, that would get you some more gain too, I am going to convert my 88lx.

roundman

thanks anyway, but I knew that already. I need some specifics like what cam profile and what size injectors and what size throttle body will still work with the speed density before the ECU won't control properly. fyi, my car is older than you! and I'm a hell of a lot older than my Stang!

bmorrisj

only thing that really matters to SD is the cam profile, too much duration and you lose vacuum and the engine falls on its face...

50fiend

This might be a stupid question but here goes. Will the motor (SD) run bad with no vacuum canister even if the lines are sealed off? ie. lack of power/fuel problems.

50fiend

Roundman. In 50 Mustang Mag this month there is a guy with road racing setup mustang that is 67. Old dudes with cool cars rule. (If they don't drive them like grandma)

roundman

yes, with a speed density computer controlled motor, the vacuum signal via the MAP (manifold absolute pressure) sensor will not be normal relative to the TPS (throttle position sensor) and this throws the computer a curve that it can't handle. (low MAP/vacuum should only occur at WOT, wide open throttle.) also low vacuum causes the fuel pressure regulator to think the throttle is wide open and it increases the fuel pressure when it shouldn't and this makes the mixture too rich for the operating condition. from what I have read, this only happens at less than WOT when the engine is trying to operate in the closed loop mode, i.e. O2 sensor signal and the others combined in the computer are used to determine the amount of time the fuel injectors are open and engine timing. at WOT, the computer goes into the open loop mode and ignores the various sensors and uses built in fuel/timing maps to determine the injector pulse timing and engine timing. aftermarket chips and/or custom tuning of the ECU rewrites these maps to increase performance since the OEM programming is based primarily on keeping emissions low and fuel mileage high, they leave a lot of performance potential unavailable.
the MAF (mass air flow) modern systems actually measures the incoming air flow rather than implying air flow from the TPS, so it can handle low vacuum conditions better because the computer knows the actual air flow at all times, it ain't guesssing based on the TPS signal. Ford went to MAF systems in 1989 across the country but it had already been using it in California because of their stricter emission laws. what I'm trying to find out is how far can I go with the cam, throttle body, injectors, etc. before the motor won't run well enough to get to the starting line where it will run at WOT.

roundman

I met a 62 year old K stock automatic racer this past weekend at the test and tune and there are plenty more like him out there still getting it done. I also know and race with a real grandma with 4 grandkids who cuts killer lights and can run the number with anyone out there. watch out for us oldies, we will put a hurtin on ya!