Need help with custom intake

[v8Toilet]

Where can I get preferably flexible hose with a smooth inside surface?

[dpeete]

Pep Boys has a 4"x72" air intake type of plastic hose for under $15. The stuff at Pep Boys is very smooth on the inside for better air flow. Smoothness isn't going to make much of a difference if you are only providing an additional inlet in to the air box. It kills you at the MAF, or around the throttle body.

[v8Toilet]

Thanks! My plan is to replace the plastic pipe that goes from the air box outlet after the MAF sensor to the throttle body with something that is more of a straight shot and smoother. I will do before and after tests on the Dyno.

[dpeete]

If that is the case, I will be doing something similar to remove the intake resonator. If you cut the resonator out of the existing intake pipe you will also remove the bend that is about 6" before the elbow into the throttle body. Using Silicone hose, you can then connect in a length of 3" pipe between the airbox and the remaining straight+elbow portion of the intake tube. You will have to weld on some bungs to attach the pickups for the hoses, but it shouldn't be too bad.

This change will remove the flexi-hose after the MAF, the intake resonator, and the bend before the elbow.

[v8Toilet]

Maybe you could tell me just what the three hoses are that connect to the intake resonator. I know the larger one is a crankcase breather and the other two appear to be a vacuum line for something. Do you know what those vacuum lines are?

[dpeete]

No, I don't know. I haven't traced them yet. My guess would be one runs to the FPR.

[Mudog715]

Originally posted by v8Toilet
Maybe you could tell me just what the three hoses are that connect to the intake resonator. I know the larger one is a crankcase breather and the other two appear to be a vacuum line for something. Do you know what those vacuum lines are?

Large one is crankcase breather.

One small one is air source for power steering load valve. Under high steering load it opens and allows some air to bypass the throttle body to stabilize the idle. Most other vehicles have an electric switch for this that provides an input to the ECU and then the ECU adjusts the IAC (Idle Air Control motor) accordingly.

The other small one, as I remember, is the ambient pressure reference for the fuel pressure regulator (iForce FPR is not connected to manifold vacuum like most older EFI FPRs).

On the subject of intake resonators, it has been previously posted (and proven) that it provides more power benefit than power loss. It has been computer-designed to match the intake resonance & volume of the engine to actually smooth out the air pulses entering the engine.

[Eddie]

Originally posted by v8Toilet
Maybe you could tell me just what the three hoses are that connect to the intake resonator. I know the larger one is a crankcase breather and the other two appear to be a vacuum line for something. Do you know what those vacuum lines are?

One goes to the fuel pressure regulator,kind of a stupid idea IMHO since they should be plumbed at the intake manifold itself to get a an accurate engine vacuum reading. You''ll never get pressure from that source if one plumbs a boost-dependent FPR with a TRD supercharger.

One of the large hoses goes to the passenger-side valve cover. I plugged the airbox fitting and connected a filtered breather to the valve cover. I don't recall what the third one goes to,I'll look tomorrow.

[Mudog715]

Originally posted by EdJadeSR5Tundra
One goes to the fuel pressure regulator,kind of a stupid idea IMHO since they should be plumbed at the intake manifold itself to get a an accurate engine vacuum reading. You''ll never get pressure from that source if one plumbs a boost-dependent FPR with a TRD supercharger.

One of the large hoses goes to the passenger-side valve cover. I plugged the airbox fitting and connected a filtered breather to the valve cover. I don't recall what the third one goes to,I'll look tomorrow.

The stock FPR is not designed to be manifold-pressure referenced. It was designed to provide a constant pressure, regardless of engine load (vacuum). Any load enrichment needed is controlled directly by the ECU in the form of longer injector pulse duration. This is a far more accurate way to meter the fuel to the engine than other EFI systems that vary fuel pressure with engine vacuum. With those systems a given injector pulse width cannot be accurately be predicted to inject the same amount of fuel every time due to the fuel pressure not being constant. Other makes use the constant-pressure arrangement now, as well, because it allows more precise air-fuel ratio control.

The reason the crankcase breather is connected DOWNSTREAM of the MAF (mass airflow meter) is because that air source, via the PCV valve, provides a bypass for the throttle body. If the air source were not downstream of the MAF then the MAF sensor signal will show a LOWER reading than actual airflow (because air is entering the engine from a source other than the MAF & throttle body). This will result in a LEAN mixture until the Long Term Fuel trim corrects it due to feedback from the O2 sensors. Bottom Line: they didn't just randomly decide to plumb the crankcase line there, they did it so the MAF (which is the primary sensor determining how much fuel to inject) would get a CONSISTANT and RELIABLE reading and therefore allow the air-fuel ratio to be more precisely controlled.

There are three good things that come from a precisely controlled air-fuel ratio:

1. more power. the more accurate mixtures result in fewer misfires and more complete burning of the fuel.

2. lower emissions. a positive side-effect to fewer misfires and more complete combustion is reduced hydrocarbon emissions.

3. less emissions controls. yes I said LESS. if the engine isn't producing lots of unburned fuel from incomplete combustion, then certain "band aid" emmissions controls can be omitted or minimized. The iForce V8 has no EGR (exhaust gas recirculation), AIR (air injection, aka "Smog Pump") and very small, low restriction cats.

[dpeete]

Originally posted by Mudog715
On the subject of intake resonators, it has been previously posted (and proven) that it provides more power benefit than power loss. It has been computer-designed to match the intake resonance & volume of the engine to actually smooth out the air pulses entering the engine.

On Tundras? Do you have a link to the post?

I had posted some stuff on an Australian Toyota engine that lost hp, but a Lexus engine that gains hp. Some vehicles show improvements, some don't. I will be testing the results by graphing MAF vs RPM, so I will be able to show exactly what happens on a Tundra.