tomgregory2000
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| posted on 18/8/09 at 09:56 AM |
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Size different between carbs and TB's
I have a c20xe on dellorto dhla 45's with a choke size of 38mm.
Now my mind is telling me that i could have a TB of 38mm id and get the same airflow through them as the 45's with 38mm chokes fitted and that
subject to correct size injectors and everything being the same it will make the same max bhp.
Am i correct or wrong?
Tommy
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flak monkey
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| posted on 18/8/09 at 10:17 AM |
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Throttle bodies will flow the same amount of air as the same sized carbs, you are quite right.
There will be negligable power change, if anything it will be better on TB's due to better fuelling control.
The main thing you would notice is an improvement in fuel economy.
You could fit bigger throttle bodies than carbs (e.g. GSXR 750s with 42mm butterflies) as you can still get the low end driveability with TB's
which you would lose with such large choked carbs.
Bit waffly but hopefully it makes sense?
David
Sera
http://www.motosera.com
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cliftyhanger
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| posted on 18/8/09 at 10:32 AM |
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AS above.
But not worth going too much bigger as you can lose low/midrange torque. Paul Dunnell confirmed that when he changed his Zetec kits from 42 to 45
TB's it lost a few BHP in the midrange but allowed a bigger (usually unobtainable) top end.....
and mine is the 45 setup
TBs suffer much much less than carbs though.
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MikeRJ
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| posted on 18/8/09 at 10:33 AM |
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I'd expect 38mm throttle bodies to flow bit a more than DCOEs with 38mm chokes simply because they have a smooth bore (either parallel or
tapered) without an auxillary venturi to restrict things.
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tomgregory2000
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| posted on 18/8/09 at 10:33 AM |
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funny enough i have some gsxr 750 tb coming my way.
Just wanted to make sure that my mind was correct
Tommy
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m8kwr
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| posted on 18/8/09 at 11:28 AM |
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I know its not the same engine, but i had a 2.0 8v vx (cav-the one with the better head!!!), on dellorto dhla 45.
I changed to hayabusa tb's, omex ecu..
I had better performance all the way through the revs, end result was 185bhp (which i did not think was that bad with no other mods done to the
engine)
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Jenko
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| posted on 18/8/09 at 01:05 PM |
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38mm - 42mm TB's will be fine for most applications up to around 200bhp............gsxr600 / 750 are a good choice because they can be spaced
and are tapered......and the injectors on both will be fine......So, yep, you have chosen well....
MY BLOG - http://westfieldv8.blogspot.co.uk/
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