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09-01-2019, 01:14 AM #61Banned
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09-01-2019, 06:19 AM #62Screaming And Flying!
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09-01-2019, 06:30 AM #63Screaming And Flying!
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With respect to piston speed, rpm , crank rotation speed and the change in position of the piston top in the closing exhaust port as the blowdown pulse arrives prior to port closing from its tuned pairing within its exhaust group.
Arrival marked as degrees before close at low rpm is greater or earlier than degrees before closing at high rpm. The piston speed outpaces the arrival of the stuffing hit as rpm increases. Timing of this arrival has different degrees of beneficial effect, ranges. Too early as a result of high exhaust port duration and or too short a distance between ports results in a negative impact at low rpm due to excessive amount of charge dilution and spilling before the port closes. But at high rpm the beneficial range is achieved. It's a balance of crank pin spacing, block exhaust system distance and ex port roof height from TDC. Higher the roof the earlier the hit is formed and released from the originating cylinder,also on the receiving cylinder this translates into more degrees before closing at arrival.
The objective is to have a system which has enough delay of arrival in built distance between pairing ports to have a good strong bottom rpm range with adequate ex duration for great high rpm power.Last edited by FMP; 09-01-2019 at 07:03 AM.
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09-01-2019, 10:35 AM #64
No, no , no FuMPy .. you say it makes a U turn and goes up a blind ally instead of straight out the highway ...
You had to use my picture since you've actually never looked in the ports of a real OMC V-8 for yourself ..
They have 2 primary conduits that merge into one .. much like these collectors.
Which provide a smooth path to a divergent cone ... same as the OMC block
However, the reflective wave is created by the "reverse cone" at the end.
Something, as a general rule, the outboard does not have ....
SS MinnowFuMPy, here's your chance to impress and shut me up, all in one shot ...
Originally Posted by FMP
Yup, as crank speed rpm increases the port to port timing arrival at the closing port is effectively later and in the most beneficial range. Although with the triple at low rpm it's still quite close to optimum and definitely beneficial. 120° spacing and distance port to port insures this.
Reverse pulse, if timed with the pairing can add to it. Reverse being the rebound from the low scavenging to high again.
Wait, what? Can anybody explain this to me? I am not a very smart man.
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Minnow , it comes from his years of study in the fields of thermo-dynamics, kenetic energy, combustion effiency and exhaust gas analysis ..
He has written ... err .. read dozens of papers on file in the U.S. Patent Office. While understanding little to none of it, it never stops him from hiding behind other people work ..
You speak of ports and porting so much. If it's more than a house of cards, then >
I'd really like to see your collection of straight, 45* and 90* handpieces and the tooling you use for stock removal and finish work. Cuz lord knows it takes quite a bit of diversity when it comes to porting a modern V-6 block ... Chaz = waiting on your very first picture
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09-01-2019, 05:39 PM #65Screaming And Flying!
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an OMC v8 powerhead has 2 outlets, they dont merge
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FMP thanked for this post
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09-01-2019, 07:36 PM #66Screaming And Flying!
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Two individual fours doing their own thing
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09-01-2019, 10:09 PM #67Screaming And Flying!
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What would be interesting is doing a left and right bank V8 crank. 1357, 2468 . Firing every 45° left to right and 90° between 1537 and 2648. If the crank and balance would permit. A left and right L4 Merc style manifold could be made for each bank. In the midsection between top and bottom pairs an exit to a tuner stack into the wind could be made. With such long equal pairing the ex duration could be high for high rpm and bottom end would still be a tractor.
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09-01-2019, 11:19 PM #68Screaming And Flying!
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Or with the original crank two modified x shaped manifolds with more equal pairing distance with a stack exit centered. How different are the race and fishing motor cranks?
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09-02-2019, 05:13 AM #69Screaming And Flying!
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The f1 v8 pairs each cyl 13, 24, 57, 68
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09-02-2019, 06:07 AM #70Member
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09-02-2019, 08:21 PM #71
Can you put your hand in your head ... Oh No !
This is a good place for a rookie to start. CHEAP +...> You won't be able to do too much damage and it works good for chamfering ports .. at least the tops anyway ... ehh
Why not making little reversecone on the end of tuner or short 0deg end��The short answer is it didn't work ...
Here's the long version as to why ..
http://www.bridgestonemotorcycle.com...ou_really6.pdf
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Hupiveneilijä thanked for this post
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09-03-2019, 01:42 PM #72
Power my brother, I want you to think about that statement for a moment.
You have an 8 lane highway, due to road construction, they have reduced traffic flow down till there are only 2 lanes.
What would the signs read along with flashing orange lights, prior to reaching the barrels and cones forcing these reductions in lane usage ... ?
# 1) Self-important idiots, run right up to the end and cause a traffic jam for all including yourselves ..
# 2 ) MERGE AHEAD
# 3) What is this highway you speak of ..
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09-03-2019, 06:23 PM #73Screaming And Flying!
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They only see each other once they get to tbe big intersection called the inner exhaust housing.
Dont forget we drive on the other side of road over here.
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09-03-2019, 06:58 PM #74Banned
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powerabout liked this post
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09-03-2019, 09:32 PM #75Screaming And Flying!
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