plentywahalla
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| posted on 17/4/09 at 08:09 PM |
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Zetec - ST170 manifold - GSXR TB's (am I missing something?)
So far so good, Bought ST170 manifold and set of GSXR1000 throttle bodies.
Re-shaped manifold ports by jigging to a perfect round and applying heat. The manifold must be a thermoplastic as it says 'recyclable' on
it, glass filled nylon I think. Need a good hot air gun as nylon needs over 200 degrees C.
Then re-spaced manifold ports by the same method so1&2 and 3&4 each matched the 80mm pitch of the TB's.
So feeling quite smug at this point as I only need to extend the linkage on the TB's between 2&3 where the secondary or choke butterlies are
not linked solid. Also as I am using the original Ford injectors and fuel rail I don't have to worry about respacing the GSXR rail.
..... Then I read on this forum that everybody seems to remove the choke butterflies.... ALSO others with the same set-up use the GSXR injectors/rail
not the ST170.
So smugness evaporates ... Am I missing something?
What cold start facility is provided by the ECU (I plan to buy Megasquirt V3) in the absence of any choke butterflies?
Why use the TB injectors when the ST170 manifold places the injectors must closer to the head and at a perfect angle to the air flow?
Why does the pope wear his underpants in the bath?
2 out of 3 correct answers please
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big_wasa
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| posted on 17/4/09 at 08:21 PM |
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Yep bin the second set of butterflys. They are not a cold start system but more a damper to stop you snaping the throttle open on a 180bhp bike 
Also known as an anti wheelie mech'.
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stevebubs
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| posted on 17/4/09 at 09:15 PM |
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ditto on the butterflies.
Use whichever set of injectors you wish.
Could even leave the second set in there for when you decide you want more power and turbo it...
Closer to head = more efficient (in theory)
[Edited on 17/4/09 by stevebubs]
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prackers
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| posted on 18/4/09 at 08:18 AM |
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Having just installed a similar setup, ST manifold but Haybusa tb's plus Megasquirt V3:
The Haybusa tb's don't have any choke butterflies in the first place, and they are not needed for cold starting, the megasquirt software
takes care of that by enriching the mixture based on engine temp.
I had the option of using either sets of injectors, and eventually went with using the bike ones and just blanked the st ones off. My understanding,
which may well be wrong, is that injectors squirting directly onto the back of the valve are better for economy/emmissions/flexibilty but injectors
closer to the throttle butterflies are better for power. My setup is reversable just in case I dont like the results from it as it is.
I did look into using both sets of injectors but for now decided just to go with one set to simplify things as I am already finding megasquirt a
fairly steep learning curve!
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Dave Bailey
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| posted on 29/7/10 at 09:42 AM |
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Prackers you have U2U
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fatbaldbloke
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| posted on 29/7/10 at 06:11 PM |
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quote:
Yep bin the second set of butterflys. They are not a cold start system but more a damper to stop you snaping the throttle open on a 180bhp bike Also
known as an anti wheelie mech'.
Exactly as he says, nothing to do with cold start, that's handled by the enrichment setting in the ECU. Take 'em off and throw them away,
you won't have the electronics to control them even if you wanted to.
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