supercat
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| posted on 26/11/06 at 11:39 AM |
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Inlet bend
Hi Guys,
I'm (slowly) getting together bits to convert my engine to EFI, however I have a small clearance issuse with the manifold and TB's -
connecting them together means they hit the chassis rail. Can I connect the TB's to the monifold using an bit of silicon hose - they make one
with a 45 degree bend at just the right size.
Cheers, James
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stevebubs
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| posted on 26/11/06 at 01:04 PM |
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Assuming you're angling them up and not down, this shouldn't present an issue.
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BenB
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| posted on 26/11/06 at 01:13 PM |
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You could have two problems- one is related to the silicon, one is because of the greater distance between throttle body and inlet valve... The
significance of either is debatable and would depend partially upon the amount of tuning going on...
The silicon hose could collapse down on itself due to the vacuum in the hose if you suddenly lifted off (ie closed butterflies) whilst giving the
engine some beans (ie producing lots of vacuum)...
Secondarily, there would be a gap between the throttle bodies and the inlet valve. One of the main advantages of TBs is the lack of distance
(therefore delay) between these items- so you'ld be getting rid of a bit of this advantage. Then again, this would also occur if you used a 45
deg bend of anything else.. and it probably wouldn't make any difference. It may effect the power curve- particularly the distance between the
injectors and the inlet valve... Longer inlet tracts often gives more low down grunt at expense of top end BHP but its a way complex thing-
that's a pretty gross simplification and probably only is true 50.1% of the time!!!
I can't think of any other problem and for most motors it shouldn't make a difference.
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oliwb
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| posted on 26/11/06 at 03:26 PM |
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Its what all of us running bike carbs are doing so shouldn't be a problem! Oli.
If your not living life on the edge you're taking up too much room!
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supercat
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| posted on 26/11/06 at 03:47 PM |
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quote:
Originally posted by BenB
It may effect the power curve- particularly the distance between the injectors and the inlet valve... Longer inlet tracts often gives more low down
grunt at expense of top end BHP but its a way complex thing- that's a pretty gross simplification and probably only is true 50.1% of the
time!!!
The manifold I'm hoping to use has injector ports right at the head, pointing at the back of the valves so its only the butterflies that will be
further away from the valves, so I guess this makes it less of a problem?
I'm hoping to use the minimum amount of hose possible so hopefully this will limit crush potential.
Would I need to shape the edge of the manifold at the hose end, at the moment there is a step, I guess I should try and round that off as much as
possible?
Cheers, James
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BenB
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| posted on 26/11/06 at 04:25 PM |
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With the setup you've described, then, it's unlikely to make much difference  . The butterfly isn't going to be that far
away and when you consider how much air an engine gobbles up when its going, a few cm of silicon hose isn't going to be much of a problem. When
butterfly to valve starts going into feet some people have put an auxillary butterfly near the engine but its debatable whether it makes any
difference!!!
After all, quite a few forced induction engines use a single suck through throttle body, so the "butterflied" air has to go through the
supercharger / turbo, to the intercooler (usually at the front of the car) and back, and only then into the engine!!! Doesn't seem to effect
perfomance in them....
The difference with a "remote" throttle body is going to be very small at high revs simply due to the amount of air being shifted. At low
revs its going to be more significant but enough to be noticable- I'd doubt it!!
Having chamfered edges at the manifold is going to be a good idea. It all depends upon what balance between effort : benefit you think worthwhile.
It will help extra a few extra BHP but most Se7ens aren't exactly underpowered... Its debatable whether its worth spending time fettling
chamfered manifolds or better to just get the car finished and spend the time saved blatting round and developing jaw ache from smiling so much 
I'd personally get it finished and leave chamfered edges to the upgrade list... I know that's what I did for the carbon butterflies in my
airbox!!! I wonder whether they'll ever get made- I think most of the time I'd rather be driving!!
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