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Trumpet/Rampipe lenght.
dhutch - 12/2/09 at 05:31 PM

I posted this on WSCC first, but its proberbly more suited to here:

Ive got what i beleave is a 1.9l CVH (will have to measure it one day to confirm to myself!) running twin dellorto 40's currently with some 16mm trumpets and some rather shocking golfclub filters.
- Been on the photo to ITG to confirm the backplate i have is one of theres, which it seams it might be, and to confirm what filter i would need for that. Job done. ish.

However this has set the mind ticking, because it did supprise me how short the ram pipes where. And with a 65mm filter (internal depth) i would have room for some slightly long ones. Else i would be tempted to get a shorter 40mm filter if im sticking with the short pipes.

So to cut a long story short, what sort of lengh rampipe would be optimum. (long, peice, how, string?)
- Would i notice any diffrence at all in swaping for a set of jenvey 40x40's or simular.
- Noting the thread in the wanted section for a set of 15mm trumpets for some dellorto 40's a feeling a swap coming on.


Daniel

Phil.J - 12/2/09 at 05:58 PM

Have a look on the Jenvey throttle bodies web site, he gives a formula for working out the optimum lengths.

dhutch - 12/2/09 at 11:29 PM

quote:
Originally posted by Phil.J
Have a look on the Jenvey throttle bodies web site, he gives a formula for working out the optimum lengths.

Not found the forumlar, but I will proberbly give thema ring at some point non the less.

Im not saying anything needs changing, or that i know what time talking about. More thinking out loud, and trying to learn what people think about what.

Triggered simply because it effects what air filter depth i'd buy if i do change trumpets. And at £77 the cost of an airfilter is a decent step to the cost of some new, or alternative, trumpets.
- Possably not the way to be looking at it, but i am non the less!

Daniel

Ivan - 13/2/09 at 08:32 AM

Converting the Jenvey figures into formulas using regression analyses the total length from Valve to trumpet end can be calculated using

Length in mm = 3,150,000/(Max RPM)

The throttle body Diam can be calculated using

Diam in mm = (0.3912 * HP per cylinder) + 19.397

This will give you an odd figure - for street cars use the next smaller standard diameter and for racing cars use the next standard Diam up.

Of course normal disclaimers apply