Pelican Parts Forums - Cam tower restrictors

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Just put em in and run it.

For those of you that may not have seen the difference between the two:

http://forums.pelicanparts.com/uploa...1111252542.jpg

Not the best pic, but will have to do I guess.

Ralph

Quote:

Originally posted by WERK-I
That would be 12 spray holes: the restrictor feeds two spray bars(intake and exhaust) with 6 holes each.

While I do not know about the NA models, 930s have 3 holes per cylinder, so 9 per bar and 18 all together.

Two spray their respective cam lobes and the third appears to be there just for cooling purposes.

Oops!
Thanks 350HP930

No problem, I was not even able to see the additional hole till I pulled the spray bars from my towers.

Back to a basic question- just why did Porsche introduce the restrictor? To keep to much oil out of the top end and consequently keep the bottom end alive at high rpm OR to boost the oil pressure at low rpm? I suspect the first is the correct answer.

PS that small hole still looks like it has more than 16 times the volume capacity of the very small holes in the squirters. Remember the volume goes up as the square of the radius so a hole that is only 4 times larger (dia or radius) than the squirter would support 16 squirters.

But again even if the restrictor is working, ie supports less flow than the bigger one, and actually reduces the output of the squirters, the pressure is still essenctially the same for all the squirters. Please!, try this with a garden hose and you will see what I mean. Unless the garden hose is really reallylong all the spray will be about the same.

Lets get a bit more technical to prove the point. Using electrical analogys, which are exactly equivalent, draw series resistors for in line restrictions, and parallel resistors for spray holes. Using a battery to represent emf or pressure you go thru a very big buss with no loss to the first restrictor, a series resistor of significant resistance. Then you travel thru another buss, the oil tube with low but non zero series resistance. How low? much much less than the restrictor. You could even proportion it using the diameter or the restrictor and the diameter of the oil tube. Then place parallel resistors along the oil line represented by very small series resistance between the parallel resistors. Do this until you have all the holes repersented. THen calculate the emf or pressure at each hole or parallel resistor. They wil be almost the same, ie very very close. This is true because the oil lines are not restrictive.

Give me the sizes of the holes and oil lines and I will give you the values to use for resistance as well as the relative pressures.

PPS that 246 hp is still 20 or more hp short of my 3.5L BMW M635 as measured on the same dyno, and its still stock. Lets get with it there.

Geez, I don't believe this! This has turned into some sort of p!ssing contest. All I asked in the original post was to have the spray bar orifices(18) mesured in terms of their respective diameters and compare the flow capacity of the total to the flow capacity of the restrictor. I really don't care how it "looks". Just looking for the imperical data like a number of other postings on this subject.
In terms of thermodynamics, the issue is not in dispute since the heat absorbtion of the heads by the oil flowing over them is reduced. Obviously, reduced flow will result in a loss of heat transfer.

This is NOT a pssing contest, execpt for the HP part. I always like to reply with my hp to those who post their hp every time cause I got more hp (usually). I post my BMW hp on this forum and Porsche hp on the BMW forum.

As to the restrictor size

1. no restrictor- the pressure at each pinhole will be the same as the main oil pressure

2. restrictor with same overall area as the sum of all the pinholes- half of the original flow and half of the pressure of the system at all the pin holes. (the radius of the restrictor is about 2.4 times the radius of the pinhole for 18 pinholes).

The restrictor shown looks about 10 times larger in diameter than a pinhole so it wouldn't be much of any restriction at all. If it is 10x then the pressure at the pinholes would be about 83% of the main pressure, the flow to the pinholes cut about 17%. Sizes are WAGs only.

Hope that answers the question.