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Boosting through Weber TB's?
laptoprob - 14/3/13 at 08:00 AM

I currently run some of these on my XE install but they are as old as the ark.(10 yrs+)

My question is has anyone run boost through these?

I know Jenvey change the butterflys for stronger versions to stop them bending when the throttle is shut.

Other worry is if they leak anywhere under boost.

Bit of a long shot i know but any advice would be a bonus

Norfolkluegojnr - 14/3/13 at 08:56 AM

Didn't the Lotus Esprit use a turbo and a DCOE style carb? not sure it'll help but might be a good starting point.

I can only talk about SU's, but the carb on my A series is different to a standard HIF44 - seals are uprated and certain lean off breathers etc are blanked off.

Norfolkluegojnr - 14/3/13 at 09:00 AM

Found it:

You can run an un-sealed carb on a blow through setup though. Lotus did it running a pair of 40's (dell'ortos). The carbs sit in a sealed plenum chamber and the pressure from the turbo is applied to that - inside and outside of the carb see the same pressure so no issues with the carb blowing a fuel and air mixture out of the spindles and whatnot.

Not my wise words, but I new i'd read it some where. i gues sspace may be an issue on a kit, but might be worth looking into.



[Edited on 14/3/13 by Norfolkluegojnr]

BaileyPerformance - 14/3/13 at 09:30 AM

quote:
Originally posted by laptoprob
I currently run some of these on my XE install but they are as old as the ark.(10 yrs+)

My question is has anyone run boost through these?

I know Jenvey change the butterflys for stronger versions to stop them bending when the throttle is shut.

Other worry is if they leak anywhere under boost.

Bit of a long shot i know but any advice would be a bonus


Weber throttle bodies - these where made by Jenvey for weber. You can boost these no problem, if the seals/shafts are worn you will loose some boost but nothing to effect performance.

What engine management have you got? mapping TBs with a turbo/SC can be hard, you need an ECU that will use the TPS and MAP. TPS for off-boost and MAP for extra fuel on boost.

Let me know if you need further advise as we have done this before on Cosworth YB, zetecs and redtops.

Cheers Dale www.baileyperformance.co.uk

MikeRJ - 14/3/13 at 10:16 AM

quote:
Originally posted by Norfolkluegojnr
Found it:

You can run an un-sealed carb on a blow through setup though. Lotus did it running a pair of 40's (dell'ortos). The carbs sit in a sealed plenum chamber and the pressure from the turbo is applied to that - inside and outside of the carb see the same pressure so no issues with the carb blowing a fuel and air mixture out of the spindles and whatnot.

Not my wise words, but I new i'd read it some where. i gues sspace may be an issue on a kit, but might be worth looking into.



[Edited on 14/3/13 by Norfolkluegojnr]


The Dellortos used by Lotus on the turbo Esprit were not standard DHLA's, they were developed by Dellorto specifically for the Lotus and have an extra jet circuit to provide enrichment as the boost rises.

However, I have seen standard DCOE/DHLA carbs successfully in a blow through system, though I don't know all the modifications required (apart from sealed spindle bearings and suitable jetting). You could probably do what AR did for the SU in the Metro Turbo and use a restrictor on the carb inlet to make it pressure sensitive.

[Edited on 14/3/13 by MikeRJ]

snapper - 14/3/13 at 07:04 PM

Webers need to be in a sealed box
The way carbs work means the internal air flow caused by the Venturi causes vacuum that pulls fuel in
If you pressurise the port flow you will blow fuel out of the various holes
Another issue is the carbs don't see pressure just airflow through the Venturi
You can suck through a weber or an SU like a Montego turbo does
Anything fuel injected is a much easier modification

laptoprob - 15/3/13 at 08:00 AM

quote:
Originally posted by BaileyPerformance
[


Weber throttle bodies - these where made by Jenvey for weber. You can boost these no problem, if the seals/shafts are worn you will loose some boost but nothing to effect performance.

What engine management have you got? mapping TBs with a turbo/SC can be hard, you need an ECU that will use the TPS and MAP. TPS for off-boost and MAP for extra fuel on boost.

Let me know if you need further advise as we have done this before on Cosworth YB, zetecs and redtops.

Cheers Dale www.baileyperformance.co.uk


Saved me again Dan.....

I have an new Emerald ecu so mapping wont be an issue really.

Thanks for the info on my throttle bodies though, think i will give it a go and i reckon if its setup right it will give better response etc.

[Edited on 15/3/13 by laptoprob]

40inches - 15/3/13 at 08:46 AM

quote:
Originally posted by snapper
Webers need to be in a sealed box
The way carbs work means the internal air flow caused by the Venturi causes vacuum that pulls fuel in
If you pressurise the port flow you will blow fuel out of the various holes
Another issue is the carbs don't see pressure just airflow through the Venturi
You can suck through a weber or an SU like a Montego turbo does
Anything fuel injected is a much easier modification


Seems to be some confusion here. The way I read the OP's first post, he is using Weber Throttle Bodies not carbs.

Slimy38 - 15/3/13 at 09:27 AM

quote:
Originally posted by 40inches

Seems to be some confusion here. The way I read the OP's first post, he is using Weber Throttle Bodies not carbs.


I was going to say the same thing, boosting through fuel injected throttle bodies shouldn't pose much of a problem compared to the headache of working with carbs.

laptoprob - 15/3/13 at 10:11 AM

quote:
Originally posted by Slimy38
quote:
Originally posted by 40inches

Seems to be some confusion here. The way I read the OP's first post, he is using Weber Throttle Bodies not carbs.


I was going to say the same thing, boosting through fuel injected throttle bodies shouldn't pose much of a problem compared to the headache of working with carbs.


Hehe

I saw that too but thought i`d let them prove points on carbs between themselves.

Dan@Bailey has pointed where i need to now anyway

Thanks again!

40inches - 15/3/13 at 02:25 PM

quote:
Originally posted by laptoprob
quote:
Originally posted by Slimy38
quote:
Originally posted by 40inches

Seems to be some confusion here. The way I read the OP's first post, he is using Weber Throttle Bodies not carbs.


I was going to say the same thing, boosting through fuel injected throttle bodies shouldn't pose much of a problem compared to the headache of working with carbs.


Hehe

I saw that too but thought i`d let them prove points on carbs between themselves.

Dan@Bailey has pointed where i need to now anyway

Thanks again!


Has anyone ever told you that you are evil

laptoprob - 15/3/13 at 02:50 PM

quote:
Originally posted by 40inches
quote:
Originally posted by laptoprob
quote:
Originally posted by Slimy38
quote:
Originally posted by 40inches

Seems to be some confusion here. The way I read the OP's first post, he is using Weber Throttle Bodies not carbs.


I was going to say the same thing, boosting through fuel injected throttle bodies shouldn't pose much of a problem compared to the headache of working with carbs.


Hehe

I saw that too but thought i`d let them prove points on carbs between themselves.

Dan@Bailey has pointed where i need to now anyway

Thanks again!


Has anyone ever told you that you are evil


My wife....daily

MikeRJ - 15/3/13 at 05:47 PM

quote:
Originally posted by snapper
You can suck through a weber or an SU like a Montego turbo does


Not that it's relevant to the thread but the Montego uses an SU in a blow through system, same as the Metro Turbo.