Air Filter/s for Race Use
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Air Filter/s for Race Use
Apologies if this has been asked before - I searched but couldn't find it mentioned.
I'm wondering what air filter set-up you would recommend for a 2L 8V race engine running 45 Delortos. I'm currently running with no filtration, which I am comfortable with for short races on our local track (Manfeild, New Zealand). However I'm concerned about running longer endurance races with the track getting dirtier and dirtier. I'm also planning to run at the newly-extended Taupo track which is currently notrious for dust and building rubble etc. from the extension works.
We have tried running with individual sock filters, and with a pair of K&N oval filters but they seem to strangle the engine above about 5500 rpm.
The next step up from those is expensive, so I'd rather make an educated choice based on others' experience, if possible.
I've included pictures of the engine bay and the dyno graph (without filters) if they help. I'm getting 149bhp at the rear wheels at 5690rpm.
Thanks!
I'm wondering what air filter set-up you would recommend for a 2L 8V race engine running 45 Delortos. I'm currently running with no filtration, which I am comfortable with for short races on our local track (Manfeild, New Zealand). However I'm concerned about running longer endurance races with the track getting dirtier and dirtier. I'm also planning to run at the newly-extended Taupo track which is currently notrious for dust and building rubble etc. from the extension works.
We have tried running with individual sock filters, and with a pair of K&N oval filters but they seem to strangle the engine above about 5500 rpm.
The next step up from those is expensive, so I'd rather make an educated choice based on others' experience, if possible.
I've included pictures of the engine bay and the dyno graph (without filters) if they help. I'm getting 149bhp at the rear wheels at 5690rpm.
Thanks!
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That's good power, well done, and of course, yes - way too much airflow for socks. They're only good for about 30bhp per cylinder.
In this case I recommend foam - ITG, and FWIW GCRE will hopefully be soon appointed as a distributor for them. I have known the owner Jonathan Douglas for a long time, very clever man. There is a case history in the GCRE manual about one of his GC engines.
There is foam and foam (!) but this firm does really invest in technology for filtration.
GC
In this case I recommend foam - ITG, and FWIW GCRE will hopefully be soon appointed as a distributor for them. I have known the owner Jonathan Douglas for a long time, very clever man. There is a case history in the GCRE manual about one of his GC engines.
There is foam and foam (!) but this firm does really invest in technology for filtration.
GC
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There is some difference. However it takes the tyres out of the picture which is good as they can be a big variation. Even wheel balance and alignment can make a difference.1969race125 wrote:
Steve - yes that is at the rear hubs. Is there a big difference between bhp at hubs and at wheels?
e.g check this dyno plot. This was from my friends car. Note the drop at about 5000rpm. some may think its a tuning fault but I was watching at the time and notice one of the wheels was way out of balance. It would have probably make another 5kw or so with a balanced wheel.
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The photo might be a bit deceiving on clearance - there's enough room to fit socks on all trumpets without the socks touching the wing. While the bottom of the airbox will need to be contoured to fit the shape, enclosing the whole space should not be too difficult. I might run something up quickly out of thin alloy just to see if it will work. Will let you know how I get on.
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lost foam technique
you can make a blank from foam (if you are in surf country visit your local boardsmith see if you can get leftover foam) in a way will fit the weird space you have. a belt sander is a quick way to shape the foam.
you can use 3M spraymount to get the first layer to stay put during the layup
then lay it up with fibreglass/ carbon/whatever fit to budget, sand it and then pour acetone (fumes !!outside!!) via a cut hole to dissolve the foam.
here is a webpage that pretty much explains the technique
http://www.mci.i12.com/carbon/lost_foam.htm
you can make up a baseplate which has the trumpets fitted. Are rampipes that are a bit shorter an option ? I'm not very familiar with webers and i'm not shure if changing the rampipe would upset the metering due to the reduction of the main jet signal strenght.
i find it a bit odd that weber rampipes do not have a rollback, adding a 1/4 radius to the edge should add about 6% flow
As a rule you need at least the diameter of the intake of space between the pipe and the wall.
hope this helps
thank you,
Joost
you can use 3M spraymount to get the first layer to stay put during the layup
then lay it up with fibreglass/ carbon/whatever fit to budget, sand it and then pour acetone (fumes !!outside!!) via a cut hole to dissolve the foam.
here is a webpage that pretty much explains the technique
http://www.mci.i12.com/carbon/lost_foam.htm
you can make up a baseplate which has the trumpets fitted. Are rampipes that are a bit shorter an option ? I'm not very familiar with webers and i'm not shure if changing the rampipe would upset the metering due to the reduction of the main jet signal strenght.
i find it a bit odd that weber rampipes do not have a rollback, adding a 1/4 radius to the edge should add about 6% flow
As a rule you need at least the diameter of the intake of space between the pipe and the wall.
hope this helps
thank you,
Joost
Joost M. Riphagen
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