More airflow with the stock cold air intake.

[Terry]

I have a ton of work into my truck. I have match ported the intake, in the process of installing a complete exhaust system complete with pace setter headers and high output coil, I removed the engine, trans and transfer case. I re-sealed and clean them up. I also replaced the motor mounts, clutch, pressure plate and throw out bearing. I have done a bunch of reading in improvement of the stock cold air system. A cone filter does not look good due to sucking in hot engine bay air. I am pondering putting a larger intake hose to the air box. Then Adding a high flow air filter. Anybody ever tried to improve the stock system?

 

[RonD]

1987 should have the larger throttle body

read here: http://www.therangerstation.com/forums/showthread.php?t=51915

But the problem with increasing the air flow will be the Speed density system computer you are running in 1987 2.9l

They can not detect more air flow like the later model MAF sensor computer systems do, so no real benefit assuming air flow is good now.

Exhaust change sounds good, a tuned exhaust lowers pressure at the exhaust valves, an actual negative pressure, in a specific RPM band so it takes less power to push out the exhaust, and that leaves more power for the rear wheels

 

[Terry]

But if the motor is like a compressor the more air in more air out. I don't believe the injection blocks any air flow. It only mixes the air fuel ratio. The density will richens the air and fuel.

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[Terry]

I have a fuel injection book at home. I will study this more.

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[RonD]

A motor is an air pump, self powered by adding and burning fuel.

So yes the more air in and out the more power it will have, which is why a 5.0l engine has more power than a 2.0l engine

5.0l engine can use 5 liters of air at wide open throttle every 2 RPMs
2.0l engine can only use 2 liters of air every 2 RPMs

And that's why super or turbo charging adds more power, if you can force an extra 1 liter of air into the 2.0l engine, then it will have more power because it is using more air.
(you also get higher compression which is another story )

But here's the problem with Speed density systems, the computer is made for your 2.9l engine, so computer has "look up" tables for how much air a 2.9liter engine will pull in at specific RPM, vacuum level(MAP), and throttle position, computer has no way of reading how much air is coming in, it is just looks it up based on those numbers and then modifies it a bit for air temp.

If you increased air flow with a cam or stroking the system couldn't respond fully to those changes without modification to its software.
It can't "see" that the engine is using more air at 3,000rpms for example, so it doesn't add more fuel.

MAF system are air flow based so cams and stroking are adapted for because air flow increased

 

[Terry]

So if you increase injector psi, it should dump in more fuel by design I think. The ecu them is really only a plc. I am just playing with this motor to allow it to run as well as it can. I know it is detuned for fuel economy.

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[Terry]

What about those performance chips

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[aspevacek]

Higher fuel pressure would not really get you more fuel dumped into the cylinder that is controlled by the dwell time of the injector. You need a higher capacity injector but most injectors in stock motors are never really driven to their max capabilities.

 

[RonD]

O2 sensor would correct over rich fuel mix.

And dumping in more fuel just gets you a flooded engine.

As you said, engine is an air pump, but with speed density it is a fixed in and out pump.

Removing mechanical fan and switching to an electric fan would probably be better for performance.
It is one of the only things that increases available horse power AND improves MPG.
Isn't much but isn't nothing either

 

[truckerdawg]

I have to say it, everything he has done may have given him 1/2 extra horsepower. Not trying to be rude but letting people know only so much can be done with stock components-heads, cams etc. Just keep a good tune-up and be happy. Or do the real hp makers-but beware!

 

[Terry]

The exhaust and egr delete are the only changes I am doing now. I have produced some seat of the pants power improvement. I am putting on the headers because I bought then for 140 dollars. My exhaust was completely shot so I will be break even or money ahead. Most things I have done make it run better but faster not sure. I understand you can't polish a turd but you can have a smoother cooler running turd.

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