kendo
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| posted on 4/10/11 at 03:31 PM |
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Crossflow Exhaust
Hi all
At long last I have had my twin 40 dellorto's set up on a rolling road (MEK Motorsport in Cheltenham) and the difference is amazing in terms of
overall driveability.
However, the power trace fell well short of predictions - 102bhp when around 120bhp was the estimate from Dave at MEK (he does a lot of classic fords
so should be a fairly well calibrated view).
(The engine is a 1660 crossflow with a BCF3 cam and twin 40's)
So, my first question is - was that an optimistic estimate?
He felt that possibly my exhaust was one area where improvements could be made. The system I have came from RH Lolocost and is a 4 into 1 arrangement
with a constant 2" diameter from cylinder head to tailpipe.
It was suggested that a 4 into 2 into 1 might be better and I have notice that lots of the escort tuned exhausts are like this and that the pipe
diameter increases with each stage.
So my second question to the collective is one in regard to the exhaust - what would be an effective set up?
I look forward to your comments.
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johnemms
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| posted on 4/10/11 at 03:34 PM |
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What was you dellortos jetted to ... ??
cheers
jon
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scutter
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| posted on 4/10/11 at 04:56 PM |
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Sorry I can't throw any light on your situation, but when I swapped the Lolocost exhaust collector for a proper merge collector on my st engine
I saw a 10bhp increase.
ATB Dan.
The less I worked, the more i liked it.
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snapper
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| posted on 4/10/11 at 05:05 PM |
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I think your primaries should be closer to 1 1/2" and your secondary's 1 3/4" to 2" into 2 1/2" pipe all the way
through.
There are a few programs on the web to do the calculations for you but 18 bhp is a big ask.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Alfa145
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| posted on 4/10/11 at 05:35 PM |
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I have a 1660 with a BCF2 cam running on R1 carbs.
Popped out 101bhp on the rollers. (at the wheels) approx 130bhp at the fly. That was with 5mm of no4 piston ring missing I found out later, so getting
it tuned again soon.
Thats with a 4-2-1 manifold of about 1 3/4" I think (too lazy to go measure but will do if you want) soon to be replaced by a new stainless
4-2-1
Should give you a reasonable comparison.
[Edited on 4/10/11 by Alfa145]
[Edited on 4/10/11 by Alfa145]
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samjc
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| posted on 4/10/11 at 05:50 PM |
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Their are variations in exhaust ie 4-1 or 4-2-1 cant remeber but both help and both increase in diameter as you go through the system but oes more
suited for bhp (top end performance) the other for tourqe but at a guess with these types of cars being so light bhp helps more so than added torque.
My 1.4 fiest runs a 2.5inch back pipe after cat so id guess you could do with a more free flow system also what back box are you using? ?
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rusty nuts
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| posted on 4/10/11 at 07:20 PM |
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My x flow made 127BHP at the flywheel using a BCF2 cam , Emerald ECU , ZZR1100 T/Bs and a Lolocost manifold and silencer
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