Nitrogeno25
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| posted on 5/7/12 at 06:30 PM |
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Throttle bodies - alpha-N driveability
I'm finishing my install with the Duratec with Jenvey 45 TBs. Running megasquirt in pure alpha-n mode as the jenvey does no provide a take off
for vacuum.
I'm a little concern about driveability at low load, when everybody said that driveability suffer with TBs, can we compare it with a carburate
car, for example?
Thanks!
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mark chandler
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| posted on 5/7/12 at 06:48 PM |
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All that happens is that a very small throttle opening lets in a lot of air making the pedal very sensitive.
Have a progressive cam so large movements at the pedal relate to small throttle openings and you remove this issue.
For a vacumn take off use some LPG fittings, drill and tap the manifold and run rubber hose (stuff that will not collaspe under vacumn) into a 4:1
joiner and take this off to the MAP sensor.
Regards Mark
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GeoffT
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| posted on 5/7/12 at 07:37 PM |
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For the same reason you'll find that a small change in throttle off idle will need a large change in fuelling (VE) - it helps if you keep the
TPS bins very close together at the low throttle part of the fuel map, maybe just one tps count apart.
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Nitrogeno25
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| posted on 5/7/12 at 07:55 PM |
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quote:
Originally posted by mark chandler
All that happens is that a very small throttle opening lets in a lot of air making the pedal very sensitive.
Have a progressive cam so large movements at the pedal relate to small throttle openings and you remove this issue.
For a vacumn take off use some LPG fittings, drill and tap the manifold and run rubber hose (stuff that will not collaspe under vacumn) into a 4:1
joiner and take this off to the MAP sensor.
Regards Mark
I'm not sure how I feel about drilling the j$e$n$ve$s direct to head TBs.
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matt_gsxr
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| posted on 5/7/12 at 07:59 PM |
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Put in some closely spaced load sites around the closed throttle.
As long as you balance them then you will be fine.
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GeoffT
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| posted on 5/7/12 at 08:05 PM |
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quote:
I'm not sure how I feel about drilling the j$e$n$ve$s direct to head TBs.
.......Mark said drill and tap the manifold , your first post did not say they were direct to head........!!
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Nitrogeno25
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| posted on 6/7/12 at 01:34 AM |
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quote:
Originally posted by GeoffT
quote:
I'm not sure how I feel about drilling the j$e$n$ve$s direct to head TBs.
.......Mark said drill and tap the manifold , your first post did not say they were direct to head........!!
You're right, sorry for that!
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jeffw
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| posted on 6/7/12 at 05:18 AM |
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quote:
Originally posted by Nitrogeno25
I'm finishing my install with the Duratec with Jenvey 45 TBs. Running megasquirt in pure alpha-n mode as the jenvey does no provide a take off
for vacuum.
I'm a little concern about driveability at low load, when everybody said that driveability suffer with TBs, can we compare it with a carburate
car, for example?
Thanks!
I've used Jenvey TBs on both Megasquirt and Omex and have never had a 'driveability' issue with alpha-n. Bike throttle bodies yes,
Jenvey no.
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BaileyPerformance
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| posted on 9/7/12 at 12:21 PM |
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quote:
Originally posted by Nitrogeno25
I'm finishing my install with the Duratec with Jenvey 45 TBs. Running megasquirt in pure alpha-n mode as the jenvey does no provide a take off
for vacuum.
I'm a little concern about driveability at low load, when everybody said that driveability suffer with TBs, can we compare it with a carburate
car, for example?
Thanks!
Alpha N is the only way to go with throttle bodies, using speed density (MAP) is worse as you end up with a big vacuum change with small throttle
opening changes.
So no need to drill your throttle bodies, just set up for Alpha N and you'll be spot on!
Cheers Dale.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Nitrogeno25
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| posted on 17/10/12 at 09:13 PM |
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Many thanks for your replies.
I try to balance the TB as good as I can, but with the bleed screws fully closed (as recommended by Jenvey) I get these readings (Cyl 1-4): 3.5, 4.2,
4.2, 3.5 Kg/h.
If can adjust to almost perfect balance using the bleed screws and the idle gets better too. I'm I doing something wrong?
Many thanks again!
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stevebubs
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| posted on 17/10/12 at 09:57 PM |
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Don't know much about the Jenveys in question but are there not screw adjusters on the linkages that should probably be set first?
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Nitrogeno25
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| posted on 17/10/12 at 10:00 PM |
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quote:
Originally posted by stevebubs
Don't know much about the Jenveys in question but are there not screw adjusters on the linkages that should probably be set first?
There is one adjuster between each par of TBs. I'm using DTH. Thanks!
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