100M Cold Airbox Filter

[TomH]

My 100M has higher HP and compression than standard. I am filtering the air intake with Denis Welch's adapter and ITG filter, but I find that the filter restricts the air flow too much. Any recommendations for a better flow through filter would be greatly appreciated.

 

[GregW]

Hi Tom,
Welcome to the Forum. What makes you think the filter is restrictive? Maybe a K&N filter like THIS would work better for you.

 

[TomH]

Thanks Greg. Performance is significantly improved with the filter removed. I experience hesitation with the filter installed. The filter I need would fit inside the air box duct hose.

 

[GregW]

The filter I need would fit inside the air box duct hose.

You want to put the entire filter <span style="font-style: italic">inside</span> the hose? If you have that setup now and you are using the DW hose that is 4.5" diameter, that maybe your problem. For your engine displacement and redline (170 CID approx. and 5300RPM) you'd want a minimum of 44 square inches of filter area. The hose has a little less than 16 square inches in its cross section.


P.S. That first filter I mentioned is way bigger than you'd really need.

 

[glemon]

Can you put one of those end of the hose type filters at the hose intake in front of the radiator and remove it when you show the car? As stated you might have restriction issues if you are looking to put a filter in the hose itself.

I know that was not your stated intent, but the hose end type filters are pretty common from K & N etc.

Afew minutes or miles of running on paved roads without a filter should not hurt things.

 

[Michael Oritt]

I use a cone-shaped foam filter that goes into the fromt end of the hose, mounted right up against the grill. I can reach in through the wheel well and remove it for cleaning.

 

[AH100M]

Sounds interesting - can you give me more details on the filter - manufacturer, part number, etc.? I assume it fits the stock cold air box hose fit to the 100M.

Thanks

 

[TomH]

Agreed. Can you furnish us with the filter info Michael? Thanks.

 

[Michael Oritt]

"Agreed. Can you furnish us with the filter info Michael?"
-----------------------------------------------
I got it from Denis Welsch several years back. I'll try to remember to measure the OD of the piece or the ID of the hose tomorrow--maybe even a photo from Santa if you're real nice.

 

[TomH]

It is the current Welch 100M Cone Air Filter that I am using and having trouble with. The filter can be viewed at:

https://www.bighealey.co.uk/category/catalogues/austin-healey/fuel/under-bonnet-100/4

 

[Michael Oritt]

Tom--

Sorry, I forgot to take that picture and if I am at the shop tomorrow I will try to remember!

In any case that is the filter that I am using. I have a square to round adaptor (Not DW's--I had it custom made because the DW unit did not make a tight enough bend) at the engine end of the hose and the DW stuck in the grill end secured by a hose clamp.

The DW site says that the filter will work on engines up to 150 HP--is yours putting out that much--that's a lot of HP? If so I assume you feel the filter is restricting air flow and wonder why you reached that conclusion.

 

[TomH]

Thanks Michael. Not a problem. Performance is like night and day with and without the filter. I experience power loss and acceleration hesitation with the filter installed. I am not certain of the car's exact HP, but it is close to 150.

 

[Michael Oritt]

Well that is impressive. I'll send a photo anyway but it looks like I cannot bring anything new to the table.

FWIW when I got my car it had no air filtration whatsoever. After having it rebuilt I thought about those nice smooth bores and all the grit flying around on the road and installed the DW filter. I try to clean it every so often and have been able to wash visible dirt out of it so I think running without some kind of filter is bad business.

 

[Michael Oritt]

Here are five photos showing the cold air box to hose adaptor and the filter which I have mounted at the front end of the hose. As you can see it is removable through the wheel well simply by pulling it out and it looks to be the same one pictured on the DW site. This photo shows it behind the grill--just to the right of the flash.

 

[Michael Oritt]

Here's #2

 

[Michael Oritt]

#3

 

[Michael Oritt]

#4

 

[Michael Oritt]

#5

 

[GregW]

Hi Michael,
Are you using that filter as Denis Welsh had intended? Seems like it is installed backwards. In essence, your only using what I've outlined in the below photo. Since the filter causes resistance to the airflow, you might be starving the engine of air.

 

[Michael Oritt]

Hi Greg--

Yes, the cone is installed backwards as I am using it at the bottom (front end) of the hose rather than the top by the CAB. But the filter is normally inserted all the way in the hose as shown in picture #3 and I can't see how that would restrict airflow, though I am always willing to be enlightened. I have no signs of starvation, at least that I know of.