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soi6
Tim east

(65 posts)

Registered:
06/24/2018 06:40PM

Main British Car:


My MGB Turbo (slow ) build.
Posted by: soi6
Date: April 22, 2022 05:02PM

MGBGT Rover 3.9 v8, Jag IRS, twin SU blow through, intercooler & rear mount turbo, the SU carbs use dynamic pressure to the float bowls & do not use any kind of restrictors on the carb inlets, this method needs very little in the way of messing with needle profiles, piston springs ect, to get the fueling correct..
MG engine.jpg
MG intercooler.jpg
MG turbo.jpg


minorv8
Jukka Harkola

(251 posts)

Registered:
04/08/2009 06:50AM

Main British Car:
Morris Minor Rover V8

Re: My MGB Turbo (slow ) build.
Posted by: minorv8
Date: April 25, 2022 12:59AM

Have you run the engine with blow thru SUs ? I am not so sure about them working without restrictors. I used to have a Mini that had MG Metro turbo package incl. blow thru SU HIF44. It has a pretty small and weird looking plenum (lack of space reasons perhaps ?) Anyway, that plenum had a substantial restriction inside. Despite it the engine revved all the way to redline. Naturally I just had to remove it (logic being that less restriction, more power). How wrong I was... as soon as boost exceeded fuel pressure it hit a wall. No way it would rev further than 3500 rpm circa. And this with a boost referenced fuel pressure regulator. Put the restriction back in and things were back to normal.



Edited 1 time(s). Last edit at 04/25/2022 12:59AM by minorv8.


soi6
Tim east

(65 posts)

Registered:
06/24/2018 06:40PM

Main British Car:


Re: My MGB Turbo (slow ) build.
Posted by: soi6
Date: April 25, 2022 12:55PM

Removing the restrictor from the Mini manifold would stop it working, you have to create a pressure differential between the fuel space in the float bowl & the air going through the carb,
Turbo bike builders have not been using carb restrictors for decades, I've not had this running yet, but I have built several turbo engines some using SU carbs, restricting the carb inlets is not the way to do it, on one of my posts some self appointed expert told me that the Mini Turbo manifold was the only thing that would work, he's 30 years behind the times.......on another forum I suggested using a pitot tube ( dynamic pressure) he remove the restrictor plates & was very happy with the results.
[www.mgexp.com]


minorv8
Jukka Harkola

(251 posts)

Registered:
04/08/2009 06:50AM

Main British Car:
Morris Minor Rover V8

Re: My MGB Turbo (slow ) build.
Posted by: minorv8
Date: April 26, 2022 02:57AM

MG Metro turbo in and ex manifolding as a whole is pretty crude and not perhaps the best flowing package. OK, given the space allowed has a lot of impact.

What is the diameter of the pitot tube, 1/4 in. ?


soi6
Tim east

(65 posts)

Registered:
06/24/2018 06:40PM

Main British Car:


Re: My MGB Turbo (slow ) build.
Posted by: soi6
Date: April 26, 2022 06:40AM

Yes, 1/4" is what i use.


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