performance manifold

[subheatadey]

Hi all,
Here's a question for you Guru's, is there a performance manifold out there for a single carb with pre-heat? I am trying to improve my airflow from the carb (I shouldn't of read 'Vizards' book on tuning!) The twin port manifold is just a T-piece which is not great for air-flow so other than having a go at making something myself whether there was a after market part out there or if anyone has had a go at doing something similar. I don't want twin carbs or single 2 barrel carbs, just to 'tweak' everything to get the most out of a stock engine.

Or am i a daft ****?

 

[jonboylaw]

Daft ****..

You could spend a long time trying to get a marginal gain that twin carbs would dwarf in an instant.

Only suggestion would be to match manifold to carb and heads.


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[subheatadey]

I thought i was

 

[Paul Weeding]

Actually cb performance makes a upgraded twin port centre manifold that flows better than a stock one!! :ugeek:

 

[Johnny69]

Daft ****..

You could spend a long time trying to get a marginal gain that twin carbs would dwarf in an instant.

Only suggestion would be to match manifold to carb and heads.


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Bit harsh!

 

[K@rlos]

Just fit twin carbs...

 

[subheatadey]

A man after my own heart......

You should read this thread I started on another forum that has a few engine guru's

http://cal-look.no/lounge/index.php/topic,21851.0.html" onclick="window.open(this.href);return false;

Enjoy

Cheers, that's a really interesting thread on the CB performance manifold, i shall give Alex a call and sound him out

 

[subheatadey]

A man after my own heart......

You should read this thread I started on another forum that has a few engine guru's

http://cal-look.no/lounge/index.php/topic,21851.0.html" onclick="window.open(this.href);return false;

Enjoy

Cheers, that's a really interesting thread on the CB performance manifold, i shall give Alex a call and sound him out

Cheers, Interesting read regarding twin carbs giving better performance than single or not necessarily so according to David Vizard page 124 - who am I to argue he knows his stuff.

 

[jonboylaw]

Every day a school day. Interesting reading.


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[madmike]

If you want the fuel to STAY Atomize you need Twin Carbs, any other type of longer intake the fuel 'Puddles'

 

[subheatadey]

It's interesting, according to David Vizard who has been tuning cars for many years particularly on smaller engines a long induction/inlet helps speed up the air flow thereby helping bottom end which is really what i want so it pulls up hills better which is what I'm after as i use it everyday for work. As far as top end I am not too bothered as then I would have to get into the gearing ratios etc, though later i shall look into either re-gearing my 3 rib box (I haven't a clue what's involved in that yet) though at best the biggest i shall go will be 1641 when I get round to it heres a groovy youtube video of someone running a 1900 on a single carb http://www.youtube.com/watch?v=Stjxa_6bszI" onclick="window.open(this.href);return false;

 

[jonboylaw]

Dave V is very well respected and wrote some seminal books on tuning the ASeries BL engine (mini). He does know his onions. I would be very interested to read the passage you are referring to. The usual case is that the long induction refers to the velocity stack and the portion non fuelled side of the carb/ throttle body. This length straightens the air flow for better velocity and hence better cylinder fill at lower rpm. I find it inconceivable that it would apply to the standard VW manifold or any derivative of. The longer the manifold fuel side of the carb/tb the higher the condensing of the fuel. Throw into that a couple of 90 bends and there is no way it will be comparable to dual, twin choke carbs.
It can be made to work, show improvements over stock, especially in a 1600, but if you up the capacity and hence the airflow requirements then it only gets worse. This is where twin carbs or manifold injection comes in to play.
Sure there are reasons to stick with the original style set-up, but it would be a misnomer label it "performance".


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[jonboylaw]

I just watched that video, interesting use of a hose clip, bet that does wonders for the airflow

Z-bed ran with stock on the same engine as mine. It works ok when jetted correctly, but will be robbing you performance when compared to a dual carb/tb set up.


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[jonboylaw]

Ok, I did some looking and managed to locate a video presentation by Dave V. He clearly states in it that the intake port length is critical, that moving to 17 inches really helps the power but becomes difficult to locate the carb.... On a Mini engine as it require inertia ram tuning, no reference to a VW motor (which I am pretty sure responds to pulse ram tuning)

Video here:
http://youtu.be/ow5cGV7bXCw" onclick="window.open(this.href);return false;
About 41 mins in.





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[subheatadey]

So far I have fitted a Vintage speed exhaust which apart from looking and sounding good is I believe running cooler than the stock exhaust which is good also every night from work I ram it up a long steep hill so that is my bench test and it is slightly better up it so maybe a extra horse or maybe a pony? I have just fitted the 'performance' maniold so once I get my std 34 pict 3 dialled back in I shall ram it back up that hill again (in third) and see If I have attraced any more livestock - I will let you know. Next job will be to slap in some high lift rockers 1:25? and see if i can tickle the sound barrier?

D. Vizard didn't work with VW I believe, but i would think the principles remain the same - it gets me out of the house though.

 

[chad]

Dave Vizard was the guru for A series and Ford X-Flow, Twin Cam etc. tuning.

I read a lot of his articles in the now defunct CCC but don't remember any VW ones - maybe the magazines readers weren't considered to be interested in air-cooled VWs.