Which throttle bodies?

[Westy2927]

Is there any advantage of omex v jenvey throttle bodies on a 2.0 Zetec or are they much the same as each other? 

[Paul Aspden (MoFast)]

I have always used jenvey’s for no other reason than the parts are easily available and the support / service team are great.

 

The thing with ITBs is getting the correct throat diameter for your application in the first place and most importantly is getting the length of the whole induction runner right to get impulse effect. 
 

I have seen so many ITBs clearly running the wrong length setup.

 

https://www.enginebasics.com/Advanced Engine Tuning/Intake Runner Length.html

 

http://www.exx.se/techinfo/runners/runners.html

[TAFKARM]

On ‎28‎/‎01‎/‎2020 at 01:40, Paul Aspden The 2nd said:

I have always used jenvey’s for no other reason than the parts are easily available and the support / service team are great.

 

The thing with ITBs is getting the correct throat diameter for your application in the first place and most importantly is getting the length of the whole induction runner right to get impulse effect. 
 

I have seen so many ITBs clearly running the wrong length setup.

 

https://www.enginebasics.com/Advanced Engine Tuning/Intake Runner Length.html

 

http://www.exx.se/techinfo/runners/runners.html

 

I was considering "others" for my Duratec build. I know there have been issues with the Omex TBs sticking on the S2000 cars and I heard about a few problems with the other reasonable new to market manufacturer (not Omex) that I was considering, having problems with their TB's sticking too. I wont name them because its all hearsay at this stage.

 

That said, it was enough to put me off and I ended up with Jenveys. As much as I like doing things differently theres a lot to be said for "tried and tested" reliability.

 

Especially when it comes to your throttle sticking open at Cadwell Park.

[Paul Aspden (MoFast)]

This is why I am not a fan of direct to head ITBs it was a concern years ago when I did an Audi based ITB conversion. 

[Jackv4]

Who manufactures the ones Dunnell engines sell??

[Ian Kinder (Bagpuss) - Joint Peak District AO]

On 28/01/2020 at 01:40, Paul Aspden The 2nd said:

I have always used jenvey’s for no other reason than the parts are easily available and the support / service team are great.

 

The thing with ITBs is getting the correct throat diameter for your application in the first place and most importantly is getting the length of the whole induction runner right to get impulse effect. 
 

I have seen so many ITBs clearly running the wrong length setup.

 

https://www.enginebasics.com/Advanced Engine Tuning/Intake Runner Length.html

 

http://www.exx.se/techinfo/runners/runners.html

 

 

That's useful and interesting. There's some good stuff here about other key dimensions too: https://www.jenvey.co.uk/support/faqs/

 

[Paul Aspden (MoFast)]

1 hour ago, Ian Kinder (Bagpuss) - Joint Peak District AO said:

 

 

That's useful and interesting. There's some good stuff here about other key dimensions too: https://www.jenvey.co.uk/support/faqs/

 

If I get chance when my rebuild goes back on the rollers I will run two different lengths of velocity stacks to demonstrate the effects. This is why OEMs run variable length manifolds especially on engines that are a V configuration where they can squeeze in a rotating barrel to get the variance.

[Dave Eastwood (Gadgetman) - Club Chairman]

The interesting thing, (well OK, i find these sort of things fascinating), although frequently the maths is spot on, it isn't always; as ever with these things, the maths typically has various "assumptions", (in the scientific/engineering sense) built in. A key one, of course being where in the rev range we want any reinforcement to be. It's not always black and white, as sometimes it can be useful to smooth out dips caused by other effects.

 

Dave at Emerald, some years ago, produced a very useful set of variable length trumpets, designed for optomising runner length on the dyno, these aloud hime to play (within a certain range, of course) with infinitely adjustable settings to tweak the individual engine.

 

He used to have a few blog posts about it on the Emerald site, not sure if they're still there.

[TAFKARM]

Infinitely adjustable settings*

 

*within a certain range

 

I'll have to remember that one for my next sales pitch! :D

[Dave Eastwood (Gadgetman) - Club Chairman]

Yep, as opposed to stepped adjustment with a range. A common enough short hand expression in techy circles

[TAFKARM]

I know what you meant Dave I was deliberately misunderstanding for comic effect*

 

 

 

*comic effect not guaranteed.  

[Dave Eastwood (Gadgetman) - Club Chairman]

 i know, it's just one of those odd little bits of engineering short hand that makes absolute sense and at the same time is preposterous!  

[TAFKARM]

Anyway, in conclusion, buy Jenveys.

[Kingster]

25 minutes ago, RussH said:

comic effect not guaranteed

🤡

[Paul Aspden (MoFast)]

10 hours ago, RussH said:

Anyway, in conclusion, buy Jenveys.

couldn’t agree more.