In a message dated 4/11/2005 6:49:04 PM Pacific Standard Time,=20 sqpilot@bellsouth.net writes:

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Thanks, Tracy....I should be able to find out in a= few=20 days. Today I removed the ram air scoop and fabricated an intake plenum fo= r=20 the 3 inch scat tubing. As soon as the NACA duct with the 3 inch outlet=20 arrives, I will install it and be ready for testing. Today I measured the=20 length of the scat tube that I will need....14 inches. Thanks again=20= for=20 sharing your experiences. Paul Conner

It is interesting that as you have noted your problem, there was=20= on=20 the other list comment made about exactly the same phenomenon you are=20 experiencing. You have found the relationship between the effectiveness of t= he=20 cowl outlet, and inlets. The rules of thumb that have been discussed on the=20= list=20 recently apply to pushers as well. You have some advantages, extraction assi= sted=20 by the prop usually, and some disadvantages, often turbulent air near inlets= =20 often making flow paths difficult to predict. Ask Perry Mick to remind us of= the=20 oil cooler troubles he had.

The real problem Paul is that when used without a sealed tube to=20= the=20 throttle body your ram air scoop pressurizes the cowl. The fact that you are= =20 seeing higher temps isn't so much a supprize, rather=20 it's expected. The better your "ram air" scoop works the worse your=20 problem. The pressure increase does help the engine make more power. That he= ats=20 up your coolant and the increase in pressure inside the cowl makes it harder= to=20 get air through the radiator, making the engine run hotter. There is probabl= y a=20 point if you could reach a high enough speed that the pressure could prevent= ANY=20 air from going through the radiator! The fixes are to re-plumb the scoo= p as=20 you are doing, or to enlarge the exit area to prevent pressure build up. Sin= ce=20 enlarging the exit may be impractical, you should fix the problem by replumb= ing=20 as you are doing. It is a shame that you can't keep the other scoop=20 easily. The type of problems you are having would seem to indicate that it i= s=20 working well! I've been away for a while and couldn't comment, but my sugges= tion=20 would have been to put a sheet of aluminum under the scoop with a 3" ex= it=20 tube near the rear plumbed directly into the TB. You would probably=20 see a HP increase at cruise. The NACA duct will probably solve the prob= lem=20 but you will lose some of the ram effect you could recover with the oth= er=20 scoop. Should be less drag though. Hang in there Paul.