Inlet Trumpets/Velocity Stack

[Steve_D]

I've spent way to long searching to no avail so will resort to challenging the PH massive.

I've seen mentioned someone has produced an adjustable length Inlet Trumpet.
I can't remember which carb it was designed to fit but suspect it was DCOE Weber.

Someone please point me in the right direction.

Many thanks
Steve

[VHPD]

Here you are Steve

http://www.emeraldm3d.com/articles/emr-adj-length-...

Edit. This link has prices for 45mm but if you call Dave I'm sure he can supply 42mm

http://www.emeraldm3d.com/throttle-body-kits/emera...

Edited by VHPD on Monday 2nd January 22:44

[Steve_D]

Now why couldn't I find them. I searched up hill and down dale.

Many thanks
Steve

[84Dave]

Steve...... in terms of the radius entry atop the velocity stack, have you looked at the www.twm-borla.com stacks? They flow extremely well, compared to stacks with a less generous top radius. BTW, just registered for this Forum..... my first reply. Recommended by a couple of gents I work with in Ireland. -Dave- U.S.A.

[Rwdfords]

84Dave said:

Steve...... in terms of the radius entry atop the velocity stack, have you looked at the www.twm-borla.com stacks? They flow extremely well, compared to stacks with a less generous top radius. BTW, just registered for this Forum..... my first reply. Recommended by a couple of gents I work with in Ireland. -Dave- U.S.A.

Welcome to the forum Dave, I am sure you will add a lot of useful information/experience to the forum

Regards
Jason

[Pumaracing]

VHPD said:

Here you are Steve

http://www.emeraldm3d.com/articles/emr-adj-length-...

Cracking article and I also then read through the entire site and the Walker's Workshop pages. Kudos to Mr Walker to be honest with some very well written and interesting stuff.

The adjustable trumpets test remind me of the K&N Torque Tubes that DV tested on the Mini engine back some 30 or more years ago in maybe Hot Car magazine or perhaps Cars and Car Conversions. They were aluminium extension tubes you could bolt to the inlet of a single SU with a cone filter on the end and I think the longest was something crazy like 33 inches which wound its way round half of the engine bay. It did indeed turn a race engine into a tractor with bugger all top end power but massive torque from just over idle. The medium length versions made a real difference to both torque and top end power.

Perhaps DV can remind us of that story. I think I still have the magazine up in the attic in a box somewhere and I'll dig it out one day.

[DVandrews]

Around 5-6 years ago we did some extensive testing with DW using unequal length trumpets, cylinders 2/3 with 200mm trumpets and 1/4 with 90mm, these gave excellent results, on a 1900 engine which was around the 210BHP mark, we picked up over 40lb/ft at one point in the torque curve (around 2500) with very little loss at the top end (203BHP). Karl at Emerald modified the firmware to allow individual cylinder trims to fuelling and timing but surprisingly the engine didnt need them.

Dave

[spitfire4v8]

Reminds me of the testing i did on inlet lengths on the tvr speed6 engine, the std airbox is pretty good (unusual for tvr!) and i tried lengths from 5inch to 22 inch from the butterfly face. here's the graph!

[BernB]

Interesting stuff...

Would the same apply to a plenum / single throttle body setup ?
Presumably you'd see benefits at part-throttle as well, with no butterfly in the inlet path to stop the pressure wave ?

[VHPD]

DVandrews said:

Around 5-6 years ago we did some extensive testing with DW using unequal length trumpets, cylinders 2/3 with 200mm trumpets and 1/4 with 90mm, these gave excellent results, on a 1900 engine which was around the 210BHP mark, we picked up over 40lb/ft at one point in the torque curve (around 2500) with very little loss at the top end (203BHP). Karl at Emerald modified the firmware to allow individual cylinder trims to fuelling and timing but surprisingly the engine didnt need them.

Dave

I will get back on a rolling road and give this a go soon Dave. I can only go to 140mm unless I cut a hole in the bonnet though. I'll email the results to you.