What Throttle Bodies

[petert 586]

I have no idea what a ZX is. I thought we were in the 16V XU section of a 205 site. Sorry.

[Anthony 1,003]

Have you/Colin offered different designs of lengthened DCOE inlets for XU 16v's over the years Sandy?

 

I'm sure that the ones I've seen before look different to the one that Mei's posted above and unless it's a trick of the photo, a fair bit longer and with a less severe angle?

 

 

More like those on Ash's Rallye for example?

[Tom Fenton 1,541]

 

have no idea what a ZX is.

It was Citroen's early 306 equivalent before the Xsara came along. Uses same floorplan and suspension layout as a 306 and a Xsara.

 

http://fastestlaps.com/photos/_Citroen_Zx_16v_mkII.jpg]

[stu8v 68 1 Cars]

Whats regarded as the best inlet tract length for the Vts/Gti6 motor?

[welshpug 1,657]

Whats regarded as the best inlet tract length for the Vts/Gti6 motor?

 

depends on state of tune.

[stu8v 68 1 Cars]

Insightful answer. ..

[welshpug 1,657]

nice vague question

[Sandy 191]

Yes there have been various Anthony, for various applications and specific requirements. Ash's with those trumpets made getting a filter on very difficult for example. There have been other occasions where to make it all fit, much steeper angles were needed. Bear in mind also that I'm not involved in the design in each case, only on the engines I've built as a rule. Another point worth mentioning is a friend of mine that deliberately uses the rather jaunty angled DCOE carb manifold on his TB'd Corsa engines, because it produces a better spread of power than the straight ones. What the eye favours isn't always what the engine wants.

 

Peter, the set up you've got in your picture there looks much shorter than Meirion's, approx 220-230mm away from the head(about 310mm from the valve)? Meirion's is about 290-300mm (about 380mm from the valve). At the top of the trumpets, the bonnet clearance in a 205 would be alot different and the tuned length benefits at shorter lengths are much reduced.

On the subject of length, there are many factors, not least of which the tract and trumpet mouth shape, you can vary the results significantly just with the trumpet shape and no length change. Using the commonly used flared Jenvey ones, I've had good results on medium spec engines at around 360 and 430mm overall.

Edited February 22, 2014 by Sandy

[JeffR 51]

Always interested to read your views on these matters Sandy. Tract length seems a bit of a black art with so many variables at play!

 

I have the luxury of the larger 405 engine bay therefore space isn't as critical as its little brother. It would appear I'm in the ballpark with mine-34cm + 8cm to the valve? I would have liked to experiment further with longer trumpets, but not much room left inside the sausage filter for that.

 

 

 

[petert 586]

Yep, mine are too short but not the limiting factor in current track times. There are far too many other variables to concentrate on at present.

[rallyeash 155]

Mine don't actually have those trumpets on from memory. I'm sure we swapped on the rollers....

[gingieboi 2 1 Cars]

Hi guys, sorry to butt into the conversation but this thread is the closest one I could find for the questions I have, I'm new to the forum so bear with me.

I'm starting an EW10 J4S engine conversion from a 206 gti180 for my 205, I'm planning to keep the engine itself standard but on throttle bodies.

My question is similar to johns at the start of the topic,does anyone know what sizes to use? 45mm or 48mm? As the engine will be kept mainly standard would 45mm be enough?

Also do I use the jenvey 118mm twins or the sf individual body taper bore, If there isn't much difference in the two then surly its not worth spending the extra on the indvidual ones but I'm guessing there more expensive for a reason, the question is, is that reason worth it?

Last but not least I have been told the jenvey manifold for this engine isn't very good so was going to get one made, probably cut up the standard one but how long should I make it, and what length trumpets should I be using?

 

also can anyone recommend someone good to make my manifold?

 

Hope someone can help shine a bit of light on the situation.

[Sandy 191]

If you've no plans to take the engine towards race spec, then 45s are likely to be the best choice, but if you intend to go further, 48s will serve you better long term and the difference in performance on the basic engine, is going to be nominal. The PAS pump is in the way of using a straight manifold, if it's a race engine, then changing to an electro-hydraulic pump is a good idea anyway, for better low speed assistance and not having to over-speed the pump at high RPM.

Twins are preferable to SFs if the spacing is close to 90mm, which at 93mm it is. They'll keep their balance better (SFs linkages relax over time) and the wear and tear is less too. TH type are shorter at 91mm and offer more flexible design than TB 118mm type, because you need to be able to curve the design for bonnet clearance. I use Jenvey DCOE TH type on my competition EW engines generally and we have a regular fabricated manifold design that Colin could supply if you wish.

[gingieboi 2 1 Cars]

Thanks that's a great help, I've already got a corsa c electronic power steering column so power steering pump isn't an issue, once I've got some funds together I will have a word with Colin.

[gingieboi 2 1 Cars]

I was thinking of running two injectors per cylinder, one in the throttle body and one in a similar position to where it is in the standard manifold, would this be worth doing or not?

Also I was looking at using the emerald k6 or omex 710, would they be suitable for that many injectors? If it's not worth doing I would probably use an omex 600.

[johniban 59 1 Cars]

deffo looking into buying some now! what ones shall i buy the 118mm ones or the 91mm ones?

[johniban 59 1 Cars]

118mm going to check out

[DrSarty 90 1 Cars]

Twin/staged injectors:

As mentioned by Kyepan earlier, they definitely add resolution and smooth out the power. Possibilities for better mpg too; at least that's what I saw.

 

Emerald definitely runs staged injectors (I have, twice). I know the DTA ECU does and would be surprised if the Omex didn't.

 

There are different ways to phase/blend the injectors, such as a complete handover, or (what I have had twice based on Sandy's recommendations as were), 50% duty cycle outer and 'hold' then inners join in. Definitely seen better results that way, even when done for the first time by John at Emerald who'd never tried the 50% approach before.

 

To the original poster:

I think you need to allocate a budget, then hunt for some of the recommendations above and stick to a plan. All of the ITB set ups will work, and different mappers will get different results. As stated: best to choose an ECU that's known and familiar to your chosen/nearest mapper.

 

Don't skimp! It's a serious investment nicely into 4 figures regardless of set up. Go for staged injectors straight off if the ITB choice and manifold length allow. For example, a short inlet with bodies will almost negate the use of staged injectors, whereas what you're looking for - certainly for well-behaved road use and cold starting - is a set of injectors in basically OE position, then a second set as far away as possible. If I recall, Tom Fenton has a second set mounted in the air filter/airbox, outside the trumpets.

 

The loom is a big job, so plan and take your time or pay circa £300 for a pre/custom made one.

 

Expect to have to alter your bonnet. Auto bonnet or other differently shaped one, or remove some of the front bracing to accommodate nice long runners or trumpets.

 

In short, unless you're brave, most things worth trying have been tried, are on this forum - or even in this thread - with stated benefits and cost; so choose one of these within your budget, considering £600-800 ITBs and inlet, £100 injectors including cleaning, £400 mapping, £200-300 loom, plus a fudge factor of £200 for adjusting hoses, an air filter such as ITG (not socks - and bear in mind the orientation of the filter logo)with back plate, trumpets if not with the bodies, a coil pack, HT leads, a catch tank and other associated hassle.

 

Easy £2000 hole in the pocket!

 

BUT, the bottom line is, if you like/liked carbs, you'll LOVE ITBs, including noise, all round driving/efficiency gains, better torque, power and engine bay glamour.

Edited April 18, 2014 by DrSarty