8 barrel, trumpets and no air filter

ChrisL · 11-04-03, 09:33 AM

Just wondering if anybody has had any real experience with running these units without air filters. My options are to either leave it open as is, or use "tea strainers" for dust protection.

I figure that, even if the engine only lasts 50,000 km (30,000 miles) without filters, thats still almost 10 years between rebuilds given the amount of driving it'll get. Am I kidding myself?

Hershal Byrd · 11-04-03, 11:12 AM

Chris,
I have put over 15,000 KM on my car and I use no filters. I tried the tea strainers and they were a waste of time and money. I had a backfire on a couple cylinders and they melted the little filter that was between the tea strainer screens. I figure it like you, just don't drive in any dust storms and hope to get as much mileage as you can. [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]
So far, this is the best air filter I've seen for weber type injection. It's on a cobra. The filter is off a diesel car of some kind.

Hersh [img]/ubbthreads/images/graemlins/smile.gif[/img]

Gary Gibbs · 11-04-03, 09:31 PM

I noticed speedway motors makes a K&N based filter setup similar to the one shown by hersh for the sprint cars. The differences are that it has a K&N in the top and all around the sides and has a carbon fiber base and high price. I thought if I ever went this route I would try to by just the filter elements (for significantly reduced cost) and make my own base from aluminum.

Howard Jones · 11-04-03, 10:43 PM

I would say that the worst thing you can do to a motor is not filter the air. I know that it looks good and most of us would have a hard time covering up 5 grand worth of art but just a little dirt down the intake can do a lot of dammage. Put a rear tire off and it will throw up a lot of dust and crap right in the back where the motor is. How about using the filter when you drive it and simply remove it when "at halter". I like the idea of making a housing for a flat k&n type filter.

John Lind · 11-04-03, 10:52 PM

Chris

Generally it is not regarded as too much of a problem unless the environment is dusty. For city use you should be able to get by OK, in the bush it can get dusty and it probably will result in significantly increased engine wear. One possibility is to get a set of those horrible sock type filters (apologies to anyone who likes them but I think they are ugly) and only use them when in dusty situations.

Regards

John

gt40rick · 11-05-03, 08:05 AM

I agree with Hersh 100%, with the GT40 the carbs are shielded from dust being thrown up by the wheels by the rear bonnet. Air for the carbs enters through the openings on the sides of the bonnet so it is relatively "clean" air.

ChrisL · 11-05-03, 10:36 AM

Hersh,
15,000 km sounds like a reasonable run, especially since you've not mentioned any sign of excessive ware yet.

Howard,
Definitely agree that air filters are much better for the engine than no filters, but I’m trying to find out if anyone can quantify from practical experience exactly how much better. Will the engine last half or a tenth as long under “normal” driving conditions.

From my perspective, GT40 ownership is generally a very impractical prospect and many compromises are made every day just to have the pleasure of owning and driving such a beautiful piece of motoring artwork. Anything that adds to that pleasure, such as the sound of the open induction, or the look of the open trumpets can only be a good thing… unless of coarse it results in having the car spend more time in your garage than on the road. It’s this balance that I am trying to establish with my question.
[img]/ubbthreads/images/graemlins/smile.gif[/img] [img]/ubbthreads/images/graemlins/smile.gif[/img]

Hershal Byrd · 11-05-03, 12:18 PM

Back in the sixties I had an old 1959 Olds with a 394 CID.
It had a fourbarrel carb. All the guys that had a car used to take the air filters out and run that way. We thought it was cool and it sounded cool. I beat that engine and it just took it. I probably put 35,000 miles on that car without the filter. I will say the carb sure looked like heck but a little carb cleaner and it was OK again. I tore the heads off once because it was burning oil. Turns out the valve guides were going bad. I remember the valves looked good. Not too bad for all that driving without a air filter.

Hersh [img]/ubbthreads/images/graemlins/smile.gif[/img]

Steve Toner · 11-05-03, 12:24 PM

How were the cylinder walls? That's what I'd be worried about - scoring from the dust...

Ian K · 11-05-03, 02:31 PM

You know, I was just checking out ITG's website.
They still have some filters in their MegaFlow
line for multi-carb set ups: JC90 and JC100.
Not sure if they are for triple carbs or what.
Might be worth a look and query ...

Ian

Ron Earp · 11-05-03, 03:57 PM

What you could do is use the standard air box under the carbs to mate with the rear deck. Then, the air only comes through the sides as mentioned.

Now, to stop big debris you could bond in some mesh screens inside these two openings and it would not be that visible. I'd certainly keep out mid-size particulates like bugs, leaves, etc. Won't keep out dust, but it'd stop a tiny rock which could wreck hell.

R

Howard Jones · 11-05-03, 06:26 PM

All I can say is that if you don't filter the air, whatever finds its way into the motor will do its worst to your motor. This is for sure a murphy's law thing. Nothing might never happen but then again a nice little pebble about an 1/8" in diameter just might go down the hole the first time you drive it. You pays your money and you takes your chances. I will tell you that I can't afford to ruin my motor on the off chance that I'm lucky. At least install those little screen covers to keep out the big stuff that might jam open the throttle plates.

**J What?** · 11-05-03, 07:15 PM

I have to agree with Howard. You have to keep the big pieces out. This summer a friend sucked a 1/4 " washer into his Can Am motor. Piston, head,valves and connecting rod all gone. This was a big buck motor with all the best components. Save yourself a lot of grief and put some screen on the intakes.
Bill

Eric · 11-05-03, 08:59 PM

The #1 most important filter is the air filter. Oil and fuel filters dont do nearly as much work as the air but if you are just racing then you will want to rebuild often anyways, but on the street....... I had just rebuilt the motor on my dirtbike. One night before an arenacross practice i rushed the bike together and the air filter didnt seat properly, I made about 15 laps and after landing from 30 feet up, the motor died, i thought i was out of gas, if it happened 3 seconds earlier i would be dead, the cause was dirt in the motor, cylinder was destroyed, the dirt was almost invisible if it wasnt stuck in the reed valve. Just food for thought.

Craig · 11-06-03, 09:31 AM

Chris, you can go without the air filters and take your chance, but I would advise fitting the rocker covers though..... [img]/ubbthreads/images/graemlins/wink.gif[/img]

40 Bud · 11-06-03, 01:20 PM

Interesting topic! I have no first hand knowledge on this subject.However I just spent the weekend with a friend at Willow Springs, running our 40's. He has webers on his 400 plus rear wheel HP. This engine was dyno tuned. They tuned totally open, wire covered and with K&N filters. Highest HP was attained with the air cleaners.

Lukas Matzinger · 11-09-03, 04:28 PM

I can understand how you would not want to cover up beautiful stacks. However, I have seen some setups that allow you to filter the air, without disturbing the engine appearance too much. Maybe these are the tea-strainer bags that have allready been mentioned.(These are pictures from Wayne Presley, he is selling a very similar filter to the one I mean).