Original comp 427 air cleaners

[Jim Vander Wal]

Check out the SecondStrike tech page. Mike has an aircleaner calculator that works well and shows a fair amount of info on different sizes. Seems to track my experience fairly well.

His carb sizing calculator is good too, albeit developed for drivability rather than peak performance. This one too tracks my experience.

Jim

[mrmustang]

Originally Posted by Jim Vander Wal

Check out the SecondStrike tech page. Mike has an aircleaner calculator that works well and shows a fair amount of info on different sizes. Seems to track my experience fairly well.

His carb sizing calculator is good too, albeit developed for drivability rather than peak performance. This one too tracks my experience.

Jim

Dating back to some time in 2000 if memory serves me correctly (might be 2001, prior to 9/11).
427 center oiler, 10:2:1 compression, 650 holley DB (already dyno tuned) fairly mild street cam as a base for the test on a "chassis" (not engine) dyno. This was done as we were baselining a new chassis dyno at a friends shop and thought it would be interesting to be able to show his customers the difference of what something as simple as an air cleaner could make.

My notes are as follows:

no air cleaner: 322hp
then 14X2 "K&N" air cleaner: 314hp
then 14X4 "green" air cleaner with drop base:324hp
then Stelling and Heller air cleaner (stock filters as we did not have K&N or Green filters in stock at the time):302hp

All of the above were done one after the other. No tweaks or changes where done to the carb or engine timing. Strictly a demonstration for about 20 customers who were at the shop that Saturday. All HP above was measured at the rear wheels.

The car was ERA321, dark blue metallic, running a toploader 4spd and 3:31 rear gear ratio.

I can confirm those where actual results, less then a few minutes apart on a brand new Dynojet chassis dyno. Real world, real wheel HP data. Somewhere in my old files I may have the torque numbers to go along with this but have yet to find them.
As a side note, the numbers above where done before we had a K&N or Green Filter-14" filter top. The filter top would add a huge amount of airflow vs the chrome lid that was used at the time of the chassis dyno runs to the tune of an additional 500cfm, just for the filter top.


Bill S.

PS: Formula wise:
Using the simple formula

A= effective filter area
CID=engine displacement
RPM=maximum RPM expected

Using the CFM formula of height X diameter x 6 x 3.14

[Dominik]

In Feb 2000 I saw a red Cobra with a strange 198 on the side featuring a (I estimate) a 3" tall, but small diameter airfilter. A silly plague on the dash said something along the lines of 198 mph. The late man's name was Joe Smith, or so ;-)

I figure this car had 530 - 550 Hp. Else, by my coast down test results in 1995 when we defined the resistance of a Cobra at 198 mph, that car would never have achieved this speed. Depending on windshield size and rake.

Would have been a 427 SO. Possibly stroked? However, perhaps back in 1968 he used another airfilter than in 2000.

For all I know, I rather have some clean lines on the hood and sacrifice 20 hp for looks.
Check Morris' evaluation of airflow over his hood. Smith's car was far less sophisticated.
Seems he didn't even have racing seats.

[jjh]

Dominik it appears that you saw one of the most significant 427 Cobras of all, the late Dick Smith's competition car CSX 3035. He was in fact clocked at 198 mph at Daytona and was the A Production national champ in 1967. I met him at Lime Rock in 2006 and he was a real gentleman. Had me sit in his car for a picture and even wanted me to put his helmet on.