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3.2 on PMO carbs: freest flowing air filters?

Posted: Wed Apr 20, 2022 4:54 pm
by 911hillclimber
I have well oiled K&N filters on my hillclimb flat 6 3.2 engine, and I'm interested to collect any views and experiences about other filters, ie ITG.
Anyone with any thoughts please?

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Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Wed Apr 20, 2022 4:56 pm
by KS
I'm tempted say 'none'...

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Wed Apr 20, 2022 5:34 pm
by 911hillclimber
The risk of swallowing kitty litter at many venues I do is too high, also the junks all over the car when towing.
I think ITG are a good bet as they do a 911 special, but there may be others.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Wed Apr 20, 2022 6:50 pm
by BILLY BEAN
I have ITGs on a 2.7 with high butterflies. The filters do not have any covers over them to restrict air flow. I have rain shields on the engine lid grill. I purchased thr ITG system from Tech9 who provides a simple flat housing for them to sit on which has large grommets to hold the assembly onto the injection tracts. Darren65 I think has the same kit on his Mongrel. Phil, who owns Tech9 uses the same set up on his personal car. He says that the power loss using his ITG set up is around 6bhp. No data to back that up.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Wed Apr 20, 2022 7:56 pm
by KS
That ITG setup was prototyped on my 74 Carrera, the first such setup they’d done.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Wed Apr 20, 2022 10:20 pm
by 911hillclimber
6 bhp is a poor return in some ways?

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Thu Apr 21, 2022 3:15 pm
by neilbardsley
I know you will not consider it but turn off the fan for the run!!

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Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Thu Apr 21, 2022 3:23 pm
by Gary71
Aircon clutch connected to a micro switch under the throttle pedal. Full throttle = fan off.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Thu Apr 21, 2022 4:01 pm
by 911hillclimber
If that was a good idea it would have been done before?

In a 40 second run this engine will rise a good 15 deg C on it's own let alone being forced into a higher temp or a more rapid rise.
I think I'll go slower and enjoy the reliability!

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Thu Apr 21, 2022 4:12 pm
by neilbardsley
Don't all formula Vees run without a fan?

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Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Thu Apr 21, 2022 5:01 pm
by KS
neilbardsley wrote:Don't all formula Vees run without a fan?

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A 1300cc four cylinder engine generates a lot less heat through friction than a six cylinder engine of more than twice the size.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Fri Apr 22, 2022 9:21 am
by BILLY BEAN
911hillclimber wrote:6 bhp is a poor return in some ways?
Maybe if what I was told was correct. Compared with loss of 11bhp from other systems using mesh and paper filters.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Fri Apr 22, 2022 10:24 am
by 911hillclimber
Difficult to work out, everyone who makes these things claim improvements.
Might get a better bang for the buck from bigger choke diameters.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Fri Apr 22, 2022 1:57 pm
by BILLY BEAN
911hillclimber wrote:Difficult to work out, everyone who makes these things claim improvements.
Might get a better bang for the buck from bigger choke diameters.
Agree Graham. I did not have the ITGs when the engine was on the dyno rig so could not make a comparative test.

Re: 3.2 on PMO carbs: freest flowing air filters?

Posted: Mon Apr 25, 2022 4:47 pm
by 911hillclimber
After a lot of conversations with cleaver people this last weekend on this subject, plan is to make some 40.5mm chokes and take the car so equipped to the RR and see what happens at the end of the season.