Multi-Throttle Bodies

[Fast Eddie]

I'm a novice when it comes to the workings of Throttle Bodies but I've noticed that V8 Supercars run multiple Throttle Bodies (8 'cos they're V8's) I think and was wondering what, if any, benefits or pitfalls would there be with running 4 Throttle Bodies on our Eurofords?

[RJO89]

Would look awesome. Trumpets popping out the bonnet!!!

[819_FLY]

I guess running independant throttle bodies means that each cylinder could be essentially tuned in regards as to how much the throttle allows air in and when, it would also mean that air in-flow would be consistant when it comes to metering air flow, where as having one throttle body at the inlet of the plenum would alow a whole heap of air to go in and the turbulence created in the plenum (usually minimal but enough) can have varied differences across the cylinders where some would be getting more air than others. Improved response would be a sign I'd assume. Quite a few of the Nissan turbo cars run multiple throttle bodies, the GTR's run 6, the GTi-R's run 4, some cars have their plenums modified to fit a second throttle body which gives improved torque down low and up highed provided its tuned properly. This is a general answer from my experience, but im sure that someone should have a more detailed answer who is specialising in this area... hahaha, i just fix cars and trucks but not too good at the designing and engineering stage, quite yet...

[Tj-zetec]

It's a reasonably simple set-up to fabricate, i was looking at a set-up a bloke had built over at sigma-galant.com forums (getting ideas about the GF's car) it was for a 2.6L astron and it looked like a webber manifold with 4 throttle bodies and an injector mounted just before the end of the manifold where it meets the head.

The issue is, however, road worthiness. essentially, they're not.
Apparently, anyone feel free to correct me if I'm wrong, the intake setup needs to be in a sealed environment (hence why modern cars run an air box). For what reasons I'm not sure.

As for racing applications, as far as i know they meet CAMS requirements (i have a manual floating around somewhere if you want me to look, that and my old man is a "accredited" scruitineer)

I have also heard rumours that there's an old escort getting around somewhere with a zetec engine and a quad TB set up, If you're serious might want to track it down.

[Mullett]

Individual throttle bodies have numerous advantages, the main one being throttle response. As mentioned before, it also balances the airflow into each cylinder (assuming the rest of the intake system is well designed) As for roadworthy, you'll need an airbox on the inlet side, which could house an individual filter for each trumpet, or be sealed and feed from a filter or filter box.

Also, this starts to get complicated. The longer the inlet runner, the more torque. The shorter the runner, the more power at higher RPM. There's some ratios around to work out the ideal runner length to suit your application, but i can't remember them at the moment. Often they'll be longer than room permits, which is why most factory manifolds are curved (to allow a long, torquey runner without taking up too much room).

Also, each runner should have a bellmouth at each end to maximise inlet velocity and swirl, and the inlet manifold ports should be matched to the head ports. The diam of the bellmouth is matched to the projected airflow and inlet volume, etc.

The reality is that for a street car, there's still lots of power and response to be had in a really good inlet setup, but for the amount of $$$ it would cost, it's not worth it.

For power, don't expect much from a straight quad-throttle swap, but your response would be fantastic. Remember that you'd most likely have to swap out the fly-by-wire throttle control for a normal cable (you could adapt the stepper motor to work, but you'd negate the gain from having the quad throttles)

If you're considering spending that kind of money...get a turbo

-RM.

[BlackLS]

Cosworth's quad tb can come with a log-style manifold that fits overthe top of the trumpets which can have filtered air supplied. Main legalities I see are needing of an air filter in a box, as well as plumbing of rocker gases into the intake.

Also need to replumb vac lines. The LR comes with a cable throttle so that helps vs the LS.

Those with the LS, apparently the plastic intake manifold incorporates a butterfly that changes the length or size of the runner depending on RPM. Some US Mazda3 guys have removed the butterfly, have lost some low-down torque but gained some top end.

[melbzetec]

According to Meridian Motorsport, they get about 180hp out of a zetec engine fitted with ITB's.(Fitted to their clubman style cars)

The problem in the Focus (LR) is that there really is insufficient space between the engine and the firewall. It could feasibly be done, but the intake is so short that useable torque for the street is crap.

I have seen it done in the UK to a Fiesta, which is a lot easier because the intake is to the front as opposed to the rear in the LR Focus (I only really know about LR Zetecs)

Pipercross make an intake box that will fit over ITB's

http://www.pipercross.net/competitio...600_airbox.asp

And they also make filters

http://www.pipercross.net/competitio...ucts_px600.asp.

I was quoted $6000 from Meridian for intake manifold, ITB's, fitting tuning, and an aftermarket ECU to control it all. Ouch.

[More revs]

Great for grunt I ran 6 on my old VB rally car. Even tho it had very agressive cam timing the individual TB's also smoothed out the low end - it didn't have that lumpy cam problem a plenum does. It gave a linear curve all the way to rocker snap.. lol

Problems I see on a road car is you would have to practically junk the std ECU or run a piggyback one. Also the std injectors won't keep up neither probably will fuel pressures and flow rates so it could end up being an expensive excersise.

but yes over 180HP I heard from a UK tuner.

A cheaper thing to make a foci fast is to lighten it up. junk anything you dont need like the spare - use a can of zzishhh. junk the interior too. I recon you could save 200Kg doing this even b4 looking at aluminium bonet and plexi glass.

I remember filling a large trailer with crap out of the VB it must have been over 200Kg saved.

[photn]

the Quads on a focus would be great and are feasible to do at a cheap price, st170 bottom inlet, and a set of gsxr tb's and it can be done. BUT you will require aftermarket management, there will be prettty much no down low torque and your fuel costs will sky rocket. the 180hp from the zetec engine in the clubman cars is only attainable without some of its accessories. you dont really need to run a cover over the TB's but it would be advisable.

In short for road use eddie its not worth it unless you have a 3k stall and shares in al major fuel companies.

if you want ur car quicker then a bluefin, tb, exhaust and what not would be advisable. but it would have a small possibly a little more impact on your fuel consumpstion.

my 2c from my research on my focus.

[20focus05]

Check out Burton for 4Cyl go fast bits ie Cosworth
www.burtonpower.com from the UK

A mate from work gave me a catalogue
Some top quad throttle body stuff they have

[Mullett]

180hp is absolutely do-able, but remember that the duratec has over 140hp standard...so that's a 40hp gain for what I guess would be cams, extractors, intake, exhaust, aftermarket ECU...and all the associated bits. I'd guess 8k if you were to pay someone to do it...much cheaper to put a turbo on it! I'd say that it's totally worth it for a 500kg kit car, but not for a 1200kg roadcar, where the extra weight of the turbo is marginal, and the midrange torque would make a huge difference to the driveability (in a clubman, you don't care if you're constantly revving the nuts off it, or how much fuel it uses, for a daily driver...I know what I'd rather

All of the above said, there's nothing quite like a really hot NA 4cyl

oh...and for an LS onwards forcus I think you'd have a very hard time putting a totally aftermarket ECU on it, the dash and ECU talk to each other...but you can tune the stock ECU

-RM.