100M Cold Airbox Filter

[GregW]

Happy New Year Michael,
Well, if you don't rev the engine much, you won't see measurable difference. With the other parts you have on the car though(DW head, headers and bigger bore exhaust) your engine can breath more than a stock one. With the ITG filter set up that way, you seem to have about half the usable filter area than the 2 original filters. The sides of the filter against the wall of the tubing are basically blocked from flowing any air at all. As Denis' site mentions, this filter can only flow enough air to make an engine of 150 HP or less happy and that's by using the entire filter. I'd think switching the filter around and richening the carbs will make a noticeable improvement.

 

[Michael Oritt]

"With the ITG filter set up that way, you seem to have about half the usable filter area than the 2 original filters. The sides of the filter against the wall of the tubing are basically blocked from flowing any air at all."
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Greg--

I never thought about that though I must say that I have had this setup for about 7 years and my engine is an EXTREMELY fast revver and will go right through redline and I often feel I have to hold the car back. Just to check I will try a little experiment with the filter both in and out and if what you say is true the difference in acceleration should be noticeable on a stopwatch, don't you think?

 

[GregW]

the difference in acceleration should be noticeable on a stopwatch, don't you think?

I think so, but as mentioned, you'd need to tinker with the fuel mixture. If you just switched the filter, you would most likely be running lean.

 

[Michael Oritt]

Randy--

Do you think such a test is best performed in a "0-60" format from a dead stop or perhaps better if done in 3000-5000 rpm's in say second gear or third gear which does not involve the variables of getting off the line well(or not)and also would keep things at or near highway speeds?

I would lean to the latter--what do you think?

 

[Randy Forbes]

3000 to 5000 RPM pulls are much more repeatable, all else being equal. So yes, that would be my recommendation, and using second (2nd) gear <span style="font-style: italic">should</span> keep you out of too much trouble.

Personally, I'm allergic to handcuffs...

 

[zblu]

Mines set up as a M also, have the tube in place to where the square to round adaptor is and where it connects to the cold air box is where the filter insert lives, I dont use it as such, I have short rams and K&N socks on with the tube supplying fresh air, only put on the cold box etc for showing

 

[TomH]

Happy New Year All! Michael, thanks for the photos. I do have the same filter and believe, as does Greg, that between the restrictive rectangular opening in the metal plate at the back of the filter, the similarly shaped cold air box intake (another restriction), and completely encapsulating the filter in the hose, the engine just cannot breathe properly no matter which way the filter is positioned. I appreciate that the cold air box and sock-type filters can be interchanged for show and go, but I'd much prefer to find a way to filter the air box without sacrificing performance.

 

[Michael Oritt]

Randy and others--

Thanks for the input and as I said though I have never felt that my car was starving for air your arguments are very persuasive. When the weather here in MD gets a bit warmer I will conduct that experiment and adjust mixture as necessary to see if there is any difference in performance with the filter in my configuration versus either inverted or perhaps just taken out for the time of the test.

I used to correspond alot with Dave Russell and as I recall he used a conical K&N in the front end of the hose and if were to shorten the hose a few inches I could no doubt make one fit so that it lands just behind the grill,cone end out to allow for max air flow.

Once it gets up into the 50's or so I will address this issue and get back to you--my side curtains aren't too weather-tight, my heater is not working and being a transplanted Southerner I am just cold all the time so we will have to wait for warmer weather to find out for sure.

 

[GregW]

Happy New Year All! Michael, thanks for the photos. I do have the same filter and believe, as does Greg, that between the restrictive rectangular opening in the metal plate at the back of the filter, the similarly shaped cold air box intake (another restriction), and completely encapsulating the filter in the hose, the engine just cannot breathe properly no matter which way the filter is positioned. I appreciate that the cold air box and sock-type filters can be interchanged for show and go, but I'd much prefer to find a way to filter the air box without sacrificing performance.

Hi Tom,
I haven't been ignoring this post, I've been struggling with my poor skills in SolidWorks.
If I were to build a cold air box, I'd do a couple things differently from the Denis Welsh offering. First, I don't like the transition from round to rectangular. I would extend the tube into the length of the box to make the transition gradual. This would also give the box a higher volume and "raise the roof" somewhat to give the air a better chance of making it back to the rear carb. Second would be to make the tube smaller, like 3" in diameter. That should still be more than enough to feed the 2 carbs. Lastly, a K&N filter that would mount on the front of the hose. Here is a little sketch I did to illustrate what I'm talking about. Added were some short stacks.

 

[TomH]

Hey Greg,
Sorry for the slow reply. I like your concept and agree with the premise. Denis Welsh simply duplicated in metal what the original AH hose did when transitioning from round to rectangle, but did nothing to improve the air flow. Perhaps this is why they do not recommend the filter for engines above 150HP. Unless I can find a better flow-through filter that I can place in the hose, I will try placing a K&N filter at the front of the hose. It has to warm up a bit here in northern IL before I can try anything! Thanks for the input.