How far can I mod a speed-density system?

[ratio411]

1990 F150 with bone stock 302. Needs a rebuild after 80k miles. I don't want anything radical, however I would like to add: Mild aluminum heads (1.9/1.6 valves) Roller rockers Possibly a 331 crank Possibly a roller block with a stock *86 HO cam Shortie headers ORP If I don't mess with the intake, TB, injectors, or go further with the cam, would I be okay by keeping the SD system? What if I put a 5.8 SD computer on the engine to beef up the maps? What if I decide to swap in a stock 5.8 SD engine? Who has experience with the "drivability" issues that are supposed to come from modding an SD engine without adding the mass-air conversion? Thanks! Dave *edit

[StrangeRanger]

Let me see if I understand this: You don't want to add a simple S/D friendly bolt-on mod like an Edelbrock intake manifold, but you want to add a stroker kit which is almost guaranteed to cause issues with the EFI system? And you consider this a minor mod? You want to use the HO cam which is designed for a MAF system in a lightweight Mustang rather than something like the Crane truck cam which is designed for S/D systems in a heavy truck? You also want to add a set of high flow heads which combined with the increased displacement and the bigger cam will almost certainly outstrip your stock fuel injection system, but you don't want to upgrade to larger injectors?

[Unlawful]

For the cost of a Mass Air Conversion, I would put it on, save yourself alot of probs, i wouldn't waste my money doing any of those mods to a S/D enigine

[ratio411]

Originally Posted by StrangeRanger

Let me see if I understand this: You don't want to add a simple S/D friendly bolt-on mod like an Edelbrock intake manifold, but you want to add a stroker kit which is almost guaranteed to cause issues with the EFI system? And you consider this a minor mod? You want to use the HO cam which is designed for a MAF system in a lightweight Mustang rather than something like the Crane truck cam which is designed for S/D systems in a heavy truck? You also want to add a set of high flow heads which combined with the increased displacement and the bigger cam will almost certainly outstrip your stock fuel injection system, but you don't want to upgrade to larger injectors?

You understand what I posted correctly.
From your bewilderment, it seems you have an answer to my question.
I just have to read between the lines to figure it out.
Apparently:
The heads and stroker will not be happy with SD.
Someone (Crane in particular) makes a cam that will work with SD.
Someone (Edelbrock) makes an intake for trucks.

I haven't figured out your answer on the injectors.
It appears you are saying that I should upgrade the injectors?

I know nothing about this subject. That is why I posted the question(s).
I didn't mean to anyone.
I was trying to give this truck a little more grunt without shelling out the nearly 700 bux for a MAF conversion.
Any other ideas, please post.
Thanks
Dave

[StrangeRanger]

The S/D system gets confused when airflow values deviate more than about 10-12% from what it expects; with a 331 you're there before you add any other parts. You can find a dyno-tuner and get your PCM re-flashed to overcome this but you're throwing a lot of money at it between the stroker kit and the dyno work. You'd be time and money ahead just finding a 351 donor in a junkyard and getting the entire powertrain, PCM and wiring harness. You're even more $$ ahead sticking with a 302 and accepting a little less performance. The money you save on not buyingg the stroker will more than pay for the MAF conversion.

Every cam manufacturer makes S/D friendly cams, Crane advertises theirs especially for trucks but Isky, Crower et al. make pieces which will work equally well. If you're converting to MAF you have even more options.

The stock intake is a weak point and will not support much of an increase in performance. You can have it extrude hned for big $$ or you can replace it. The Eddy is designed specifically for trucks; other aftermarket manifolds such as the FRPP GT-40 will also work.

The stock 19# injectors begin to limit out somewhere around 245 HP, assuming a BSFC of .5 and a duty cycle of 80%. They may support as much as 285 HP if you push them to 90% and a BSFC of .48. After that you need to upsize the injectors or raise the injector pressure. It doesn't matter what else you do to the engine, it won't make any more power than the fuel system will support. If you don't build the fuel system with sufficient capacity, you are in grave danger of leaning the engine out and burning pistons. But oversizing the fuel system doesn't do any good either. The PCM will provide only enough fuel to keep things at or near stoichiometric. Any excess capacity over what you need provides nothing.

The biggest advantages that AL heads provide over iron are weight reduction and the ability to support higher compression ratios. Weight reduction doesn't mean nearly as much in a 5000# truck as it does in a 2800# Mustang. Unless you intend to bump the CR to above 9.5 you might want to be looking at iron heads.

Basically, treat the engine as a system and select all the modifications to complement one another. You cannot categorically rule out certain changes for arbitrary reasons; those may be the exact changes that your engine requires.

[ratio411]

Originally Posted by StrangeRanger

You want to use the HO cam which is designed for a MAF system...

I might be totally lost, but the 86 HO was the only year fuelie that used an SD system, and the only year for that cam spec.
That is why I was considering that cam.
You have a point about the vehicle weight, however, this cam does not spec out any larger than aftermarket RV cams.
Just a thought.
Dave

I just noticed that I did not specify the 86 HO cam in my original post!
My fault, but that was the cam I was wanting.