which air filter (weber 45)

mpk490p · July 26, 2007, 10:43:02 AM

i have just put the rx on the dyno and im loosing 12BHP through the air filter!!
current set up is a K&N with a top on the box (pic)
im looking to get a alternator relocation bracket so that is out the way but i have a couple of options with the filter, dont want to go for just a grille really so it looks like either a ITG or piper, has anyone used these aplications?
thanks

MikeLMR · July 26, 2007, 12:13:08 PM

the ITG ones don\'t flow too well or so I am told.

What about an aluminium airbox and a really big cone filter? you can get some cool air to it as well then.

I have "tall" K&N but it is for a 48DCOE and not a 45.

How much power did you get on the dyno then?

mpk490p · July 26, 2007, 07:56:33 PM

Quote from: MikeLMRthe ITG ones don\'t flow too well or so I am told.

What about an aluminium airbox and a really big cone filter? you can get some cool air to it as well then.

I have "tall" K&N but it is for a 48DCOE and not a 45.

How much power did you get on the dyno then?

did think about a top hat and cone filter, spoke to some guys who where using ITG filters for drag racing and he swore by them, i want to get something that doesnt have a top on it if possible (surley that would give me better air flow?)
Mark

MikeLMR · July 26, 2007, 09:32:27 PM

an air filter isn\'t usually a worry if you are drag racing

6hp is a lot if you are only running the car down a 1/4 mile of pristine tarmac and then shutting it off.

what about one of the Dome type ITG filters ... the ones i have been told don\'t flow so well are sock type you have picture. I used to have (still have somewhere) and ITG JC50 which is for twin carbs but they do single versions too I think.

TonyC · July 26, 2007, 10:23:04 PM

How do you know you are loosing 12bhp through the filter? Did you run with the filter off?
I would avoid the foam filters, I\'ve been warned off them by several tuners (this is for my old carb fed race car,not the new rx7).
The K&N\'s are usually pretty good - I use to run one on the B with good power. Is the filter clean? I use to clean mine every couple of races. My car was running very poorly at a race at Rockingham, and I cleaned the filter between practice and the race - the difference in grunt was noticable, and the car ran smoother.
Do you have any \'ram pipes\' inside the filter (or trumpets), they make a difference to the air flow into the 45 with a big filter. If they are very long then airflow will actually be restrcited with the filter on.

I love carbs, so much easier to deal with than bleeding injectors and ECU\'s

mpk490p · July 26, 2007, 10:39:54 PM

Quote from: MikeLMRan air filter isn\'t usually a worry if you are drag racing 6hp is a lot if you are only running the car down a 1/4 mile of pristine tarmac and then shutting it off.

what about one of the Dome type ITG filters ... the ones i have been told don\'t flow so well are sock type you have picture. I used to have (still have somewhere) and ITG JC50 which is for twin carbs but they do single versions too I think.

Mike, the picture i used was not the best it was the JC20 i was talking about

mpk490p · July 26, 2007, 10:42:02 PM

Quote from: TonyCHow do you know you are loosing 12bhp through the filter? Did you run with the filter off?
I would avoid the foam filters, I\'ve been warned off them by several tuners (this is for my old carb fed race car,not the new rx7).
The K&N\'s are usually pretty good - I use to run one on the B with good power. Is the filter clean? I use to clean mine every couple of races. My car was running very poorly at a race at Rockingham, and I cleaned the filter between practice and the race - the difference in grunt was noticable, and the car ran smoother.
Do you have any \'ram pipes\' inside the filter (or trumpets), they make a difference to the air flow into the 45 with a big filter. If they are very long then airflow will actually be restrcited with the filter on.

I love carbs, so much easier to deal with than bleeding injectors and ECU\'s

Tony,
i do have trumpets on and they are quite long, we ran the car on the dyno with the filter on then off and saw the 12 BHP difference
pip at WGT recormended a big filter hence the questioning!!
Thanks

Mark

TonyC · July 26, 2007, 10:47:07 PM

You could try shorter trumpets - It\'ll be trumpet length vs filter height that is loosing the grunt. I\'m pretty sure K&N do a higher filter than the one you have.
Ah, I\'ve spent many a happy day on the rolling road with a car, a carb, trumpets, jets, etc.

mpk490p · July 26, 2007, 10:50:47 PM

Quote from: TonyCYou could try shorter trumpets - It\'ll be trumpet length vs filter height that is loosing the grunt. I\'m pretty sure K&N do a higher filter than the one you have.
Ah, I\'ve spent many a happy day on the rolling road with a car, a carb, trumpets, jets, etc.

there is some room for a bigger filter, would one without a top like the itg over the weber i have make much differnce? or like you say shorter trumpets (wish i had a dyno!)

mpk490p · July 28, 2007, 05:27:06 PM

i have a turbo hat that bolts straight onto the carb (just incase i want to go turbo), it comes back over the carb to the left and would need another 45 degree elbow but i could stick a cone filter on that, would that affect the air flow (having a double 45 degree turn?)