vizzard carb mods for a turbo?
Turbo Mini Forums

they worth doing?

IMO, no.

Others have done though...

I agree with Dave. My NA 1380 runs the mods and it works very well but it's a lot of effort which I don't think would be rewarded in a turbo application.

Every day is a school day ...........

How fast and how expensive ...... the same question...

any boost is added on top of whatever power you have , and anything you can do to increase the power of the engine , whether its head flow carb flow manifold flow etc ,is worth doing ,on the other hand , if you are making an engine that will rev to a point that needs the carb to flow more air is another point , if the carb flows enough for 6000 rpm , in a naturally aspirated engine without making a restriction and your turbo is going to a rev limit of 6k ,then there is no point in making the carb flow more .
on the other hand if your maknig an engine to rev to 8 k and the carb starts creating a restriction at 6500 , then its wirth doing whether it na or turboed,it means that you will make more power on the same boost ,so you can run less boost to reach your goal .
regards robert

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

In my opinion, its one of the few mods that you can do for free, so why not.

it does help, but im not saying how much

i'm along the "its free and easy to do so why not" kind of route!

right what vizzard book is this in?
i have one on modding your mini with suspension mods the lot but i carnt find these carb mods i hear about all the time!
also theres nothing in my version about turbo minis (if there is a version with that in?)
is it the yellow book? is that just on the engine?

cheers
josh

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

I think its in the bible (tuning bl's a series). from what i remember its all about making the butterfly shaft less of a restriction by filing the bolts down and cutting half the shaft away where the butterfly bolts to it. To be honest i think the gains are not worth the effort on turbo engine.

On 10th of Apr, 2007 at 10:34pm iain said:
i'm along the "its free and easy to do so why not" kind of route!

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

It's in this one...

I've already shown from flowbench testing what size 'hole' you'd need in a piece of plate to act as an equivalent flow restrictor - this was 37.5mm.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=513

So, lets work out the area:
(Pi*(37.5^2))/4 = 1104.5mm^2

Dia of the butterfly disc is 44.45mm.
(Pi*(44.45^2))/4 = 1551.8mm^2

Area of the butterfly shaft is:
44.45*5.95 = 265mm^2
*assuming square ends on shaft and a 15/64 shaft diameter - I don't know what it is though)...

Hence area at butterfly = 1552-265 which equals 1287mm^2.

If this was less, or within a few percent of the 1104.5mm^2 of the plenum restrictor - I'd say the mod was worthwhile.

I just can't see how making any area larger than the greatest restiction element will make a significant differnce however???

Anyone get what I'm trying to say?

Chain is only as good as it's weakest link..

Every day is a school day ...........

How fast and how expensive ...... the same question...

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Chokes are something else though - they are designed to speed up the air; something you can't possibly accuse the restrictor in the plenum of, with it's exceptionally 'wierd' shape that is nothing like a bellmouth, but clearly works well.

Easy test in this case is to put a box-stock SU on a flowbench, and see what can be dragged through it, and then compare to a factory plenum.
If the carb has a larger number - then there is the answer.

Now, who has a flowbench LOL!

Edited by turbodave16v on 11th Apr, 2007.

take daves words as gospel!

how does he get his woks so shiny!!!

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Do the same airflow principals apply, for air under atmospheric pressure, as to boosted air ?

The restrictor used may be an odd shape....but is that 100% by design, or because it was easy and cheap to make it like that ?

Vizard does touch on restrictors for boosted carbs a little, and they look nothing like what BL used on the metro.

What do turbo Dellortos use ? do they have any form of restrictor at the mouth, or do they simply choke em down ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

http://www.geocities.com/jharkola/1380turbo4.html

Perhaps TurboPhil would be so good as to show us what the inside of the janspeed plenum looks like - and how it compares sizewise to the chokes (I seem to recall Jukka asking phil this some time ago - or it might have been a jetting Q ???)

In all the years i've had it i've never actually taken the plenum of the carb ! Lol.
I'll take it off at the weekend and get some pics.

WWW.TURBO-MINI.COM

get some pics of your sister whilst your at it phil

LOL@Nic

-MINI CLUBMAN 1380 TURBO-