350i Velocity trumpets.

[mrzigazaga]

Hi Peeps...A short while ago i had all the fuel rail fuel hose replaced and did request the trumpets to be cleaned if needed...Unfortunately the clips that were used have failed on three sections leaving a puddle of fuel in the vee...
However i have managed to get a new clip on one where the clip broke after a slight tweak and have tightened up what i could but obviously there are some i cannot get to under the plenum so i will get some high torque clips and replace them all for peace of mind.

While the plenum is off i may clean the trumpets if they haven't been done or need doing again but was wondering if shortening them really makes a difference to torque?..I know they should be different lengths and a wider flange...(Ooo missus) achieves a smoother flow but wondered what difference it would make to a 350 if any?...Not that I'm going to start cutting them down, Just curious to know...Although i think i have a spare base and set somewhere...

I have been offered a trumpet base that has no trumpets but has fluted openings instead..Is this worth considering?...And lastly if any of my existing ones are loose what is the best adhesive to re-fit them with please...Cheers...Ziga

[Wedg1e]

As I recall, shortening the trumpets moves the torque curve further up the rev range, so as long as you want to thrash it then no problem

The trumpets ae actually all the same length, but they sit at differnt heights in the trumpet base to create equal-length inlet tracts for all the cylinders.
Supposedly on a larger-capacity engine the proximity of the trumpets to the roof of the plenum was creating airflow issues which was one reason why they were shortened but it's doubtful you'd notice any difference on a cooking 3.5 - I can't honestly say I noticed any difference when I put a -15mm set in the 390SE.

My opinion, FWIW, is that a plenum insulator would be more useful as it reduces heat soak into the plenum.

[mrzigazaga]

Thanks Ian...I will just give them a clean if needed....

[jon haines]

I have tried shorter trumpets on mine and all it did was decrease bottom end grunt and increase top end grunt which is pretty pointless really so went back to standard ones. As said they were used on bigger engines and was beneficial.

[griffdude]

Zig

Here's an effective bit of bling that might appeal-

http://kitsandclassics.co.uk/engine-ecu/

[mrzigazaga]

griffdude said:

Zig

Here's an effective bit of bling that might appeal-

Thanks for that...Someone told about those last night...That would go nice with my S102.........Right ..Wheres that antique tea pot... (sorry nan)....Ziga

[Number 7]

Mark, I believe that the trumpet base with radiused inlets was used in the Taraka conversions which TVR Power did / do - probably to give higher peak numbers, but possibly at the expense of something lower down. On an otherwise standard 3.5, I would not bother TBH. On the 4+ litre cars, it is worthwhile going bigger trumpets, but you need to do everything to get the real benefit of better breathing: inlet manifold, throttle body/disc, loose the AFM(!), big valves etc.

[mrzigazaga]

Thanks Paul...I doubt if i will bother TBH...Im happy with the car at the moment and i will just clean them out as I'm going to have to remove the plenum to fit some good clips on the fuel hose to injectors...Cheers...Ziga

[The Hatter]

Standard intake tuning...

Long runners = more low end torque and better acceleration if done properly.
Short runners = more top end power for the marketing people to rant about, potentially higher top speed if the gearing is correct, a feel good 'coming on cam' sensation but possibly (and most likely) slower acceleration!

The runner length was no accident, but may suit an SD1 with an auto trans better than a TVR. Horses for courses.

[adam quantrill]

griffdude said:

Zig

Here's an effective bit of bling that might appeal-

http://kitsandclassics.co.uk/engine-ecu/

Ha - you would need a perspex plenum cover to show it off though!!!

[spitfire4v8]

adam quantrill said:

griffdude said:

Zig

Here's an effective bit of bling that might appeal-

http://kitsandclassics.co.uk/engine-ecu/

Ha - you would need a perspex plenum cover to show it off though!!!

Or just be so fast in your class that you're politely asked not to come back the following year
Griffdude uses one of my blended bases and seems was too fast to race. He's since changed sprint series ..

https://www.youtube.com/watch?feature=player_embed...

[Wedg1e]

spitfire4v8 said:

... my blended bases...

Ah good, some proper engineering

I've used the epoxy trick to fill in the base cavities myself, usually bevel the base of the hole so that it makes the epoxy tapered and unlikely to fall out... so far

[c pryor]

I would not change them from original design. Austin-Rover/Land-Rover developed a cracking engine with that 3.5 litre. Certainly (in my humble opinion) the best engine out of all of the Rover incarnations with a perfect torque curve/driveability, so I would say leave it as standard.