[zonker]

I've been experimenting with cold air intake tubes on my '91 2.3.

I started off by disconnecting the hot air tube and removing the flapper valve from the air box, removing the maf sensor screen, and installing a Accel drop in square air filter element (like a K&N filter)

The car ran a little bit stronger and my mods seemed to help.

I then turned my attention to the intake tube by taking the silencer and removing the resonator tubes inside. The car seemed to have lost a little bottom end and maybe picked up a minor amount at the top end.

This led me to think that by gutting the silencer, I may have altered the lower rpm MAF sensor readings unfavorably by increasing the amount of air volume in the intake tube between the throttle body and the maf sensor, causing a dampening effect of the MAF's airflow readings (which would mean less fuel and ignition advance).

With the volume increase, I think it may longer for the MAF sensor to register the increased amount of air flowing thru it until it's already into the higher rpm ranges.

I then tried replacing the resonator tube section with a straight piece of 2.75" aluminum tube. The car responded favorably with better low rpm acceleration and the same good seat of the pants feel at high rpm as with the gutted resonator.

So why stop there? LOL I then tried reducing the size of the tube to 2.25" as well as smoothing out the inner shape of the tube by replacing the ribbed upper elbow and I felt the car got stronger at the bottom end and still kept it's hi end hp gain.

I now believe an ideal torque-biased intake for 1991-1993 MAF equipped 2.3's (ones that are keeping their stock MAF, cam, and fuel injectors that is) is to go smoother and smaller diameter than stock (but still staying larger than the MAF sensor tube opening).

Why? Because now the intake tube has less air volume to effect a flow increase at the MAF sensor when the throttle plate is opened, which tells the engine computer to add more fuel and timing advance sooner than if the air volume between MAF and TB was stock.

[ocejo]

pictures please...........

[zonker]

[zonker]

[zonker]

[92mustang04yfz]

Is that 2"^? I ran 3" pvc pipe into a cone filter. looks good ill get some pics

[zonker]

Read this post, you'll find 3" tube on a stock MAF equipped 2.3 doesn't work as well. This one is 2.25" in order to reduce air volume between the TB and MAF.

[blaten22]

Would be nice to see if this works with a speed density motor. <--89 2.3 Stang. I've been following your read on the Junkyard pulley setup and most likely doing this soon.

[zonker]

Originally Posted by blaten22 Would be nice to see if this works with a speed density motor. <--89 2.3 Stang. I've been following your read on the Junkyard pulley setup and most likely doing this soon.

The 87-90 motors will benefit from a larger tube since the air volume between TB and air filter has no effect on the ecu's ability to map out the spark and fuel curves. I'd bet a nice setup would be a 2.75" or 3" tube either a gutted stock air box/k&n style drop in filter, or a shrowded round open element filter.

[87fourbanger]

I have the 2.75 tube w a big specte cone filter from oreily. Mine is an 87. Was that a bad move?

[zonker]

Originally Posted by 87fourbanger I have the 2.75 tube w a big specte cone filter from oreily. Mine is an 87. Was that a bad move?

No, probably not, but without seeing a pic it it's hard to say if any improvements can be made.

Air flow through the intake tube should be as seamless and bendless as possible, so if you have a lot of sections or irregular shapes in the tube then that could be an issue.

Also material construction is a concern too. Using a steel tube for example will retain heat longer than aluminum or plastic/pvc, and you want the intake air to be as cool as possible for maximum density.

[87fourbanger]

The pipe is aluminum. I'll try to get a pic on here soon

[mattabater]

zonker whered you get the pipe and all the parts for this? info on all that would be superb!
i just removed the silencer and resonator part altogather with an alum duct pipe and elect taped it up but its alot bigger then the maf and the elbow... so i need the info on those two parts you used lol the pipe and elbow!

[mattabater]

o and what did you do with the hot air coming from the exhuast mani?

[zonker]

91-93 2.3 2300 Mustang 4 Cyl. Performance Intake Kit - eBay (item 260752026608 end time Mar-20-11 16:22:40 PDT)

[Phinney]

Reading this made me curious. My turbo'd still has the large vam, but it has the ribbed rubber hose going to it. Would I see any benefit by going to a smooth metal tube? Same or smaller Diameter make a difference without MAF? For information, after I get my quarterhorse up and running I will do a MAF swap

[mattabater]

nice thats the exact set up

[zonker]

Originally Posted by Phinney Reading this made me curious. My turbo'd still has the large vam, but it has the ribbed rubber hose going to it. Would I see any benefit by going to a smooth metal tube? Same or smaller Diameter make a difference without MAF? For information, after I get my quarterhorse up and running I will do a MAF swap

getting rid of the ribbed tube for a smooth one will be a plus, that would be a good choice.

the smaller tube should decrease the reaction time for the vam door to move, but will decrease the volume of air able to pass thru the tube, so it'll prolly be a little experimenting in order to find the setup that gives the best compromise with VAM reaction time and hi rpm WOT airflow.

[BrianF]

when you took off the hot air tube, did you left the hole in the airbox open?

[zonker]

yep, i just left it open. If the flap is removed from the airbox, then the additional opening from the tube will help bring more air to the filter.

in the past i've also mounted the hot air hose and re-routed it to have it's other end point toward the front of the car.