45 DCOE Webber Carbs

[Delbert]

Yup this should be on an MG Forum but when asked I was given replies that involved polish 😳

 

So

 

The 3000 6 cylinder engine is getting triples .

 

The bit I've either forgotten or never knew is the length of the RAM pipes

 

Apparently the longer the pipe the lower down the rev range the power builds

 

so as the MGC engine takes relaxed and laid back to a new level

this is what I am after but a smother aitflow into the carb gets me power at the low end Why?????

 

Also low end power will improve acceleration won't it

 

And yes I am looking forward to balancing them

 

Thanks in advance , the only other "experts" are trying to sellme the buggers!!!!

 

I spit on your Emeralds give me SUs

[Foxy Smith]

Delbert, the way I think of it is like musical instruments. Short instruments make higher pitchesfrequencies, like a piccolo/flute. Longer ones like a tuba/alphorn make lower pitches/frequencies. At low revs the chances of getting helpful pulsing in the inlet tract are better if the "instrument" is a low frequency long one.

 

There is an element of luck/trial and error to this but generally it applies. This is why motorcycle air trumpets are very short (15-35mm) all the punch is at the top end.

 

The theoretical ideal length of inlet tract for a modern OHV engine I believe is about 12 inches, measured from the back of the inlet valve, you can lengthen that if you want a better torque curve/ move your peak power down the graph.

[oilyhands]

There is also the momentum of the incoming charge to consider, a short induction length will contain less mass of air and therefore will have less momentum, therefore the air will stall much more readily between induction strokes than with a long induction system. If the air continues to move between induction strokes then it will be piling up behind the inlet valve as the valve opens rather than having to be accelerated again with each stroke. This improves scavenging and therefore VE. The linger the induction the lower in the rev range this occurs, hence boosting torque lower down. The downside of this occurs at higher RPM where air speed increases dramatically and drag becomes a factor.

 

I would go for the longest trumpet that can be accomodated, just ensure you have sufficient clearance between the end of the trumpet and any bulkhead/inner wing.

 

Oily

 

Edited by - oilyhands on 24 Oct 2007 08:54:57

[Delbert]

Thanks for the "independant" advice

 

I'm going for the long as its mainly for low end and 0-60 improvements I'm after.

 

As a laugh I might fix one long and one short to each Webber and see if I get it at both ends!!!

 

I spit on your Emeralds give me SUs for now, then webbers

[I.Mupferit]

Out of interest, when I was in Maranello with my son a couple of years ago, we were fiddling with a V10 F1 engine on display in the Ferrari museum and was interested to see that the induction length was variable if you twisted a lever. This obviously allows them to have the best of both worlds although probably not worth engineering such a solution on an MGC Del.

 

I don't suppose we were meant to touch it but when you've got an F1 engine within reach of two engineers and some levers just begging to be touched, well the outcome was inevitable.

 

Brent

(aka Arfur Nayo)

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

 

Edited by - Brent Chiswick on 25 Oct 2007 07:58:59

[Drumster]

well the outcome was inevitable.

 

That translates as; you broke it

 

Chris Alston

C7CAT 1800 Supersprint

R248.89 ....and then I jumped in