Larger single throttle body?

[sammyhale22]

Anyone know of a larger throttle body that could work on the Phase 2 172? or be modified to work ?

 

[PARTRIDGE172]

Anyone know of a larger throttle body that could work on the Phase 2 172? or be modified to work ?

Well i dont know if its gonna make any difference atall,but im working on a spair 1 in work. im boring it thru bigger, it can only go 2 to 3mm max wider tho. will be done mid week so i will let you know. it aint costing anything bare a bit of time, so i thought id give it a crack. quite hard taking it apart tho, it aint really designed to come apart, and you have to make a new butterfly to the new size.

 

[Chrisjk]

There was a single throttle body kit that gdi did some years back, for the cost though itb's would be better.

 

[Russ_16v]

I did a test a few years ago testing the vacuum on my old ph1 inlets on full throttle, and we found it could have taken more air in - ie the inlet was not at a point where its flow rate was an issue, but for what we could work out its not worth it - the shape of the inlets are not great, due to being mismatched and an open design, so i didnt bother fitting my 70mm jenvey tb i had. with how much extra air itbs such in for the gain, a larger single body would at best get 1 or 2 bhp and at worst mate the car drive poor due to the large instant throttle opening combined with the large intake area.

so from my experience and working id say no its not worth it mate.

 

[sammyhale22]

What if you had the material bored out on the plenum and manifold?

 

[focrs]

jenvey do large single throttles not sure if they do them to suit clio tho. I was looking at them for my custom inlet manifold.

 

[Russ_16v]

What if you had the material bored out on the plenum and manifold?

Even matched inlets dont give the increase needed for the larger single body in my opinion. The unmodified manifold could take more air in, but bear in mind the increase that itb's give, (with x4 45odd mm inlets) the extra that an enlarged tb would give would be tiny - a few bhp at max on a standard spec engine, but with a much snappier throttle - as you will be letter more air in as you open the throttle - you will end up kangarooing everywhere lol.

jenvey do large single throttles not sure if they do them to suit clio tho. I was looking at them for my custom inlet manifold.

That was the one used in GDI's (ahem) conversion, and I used to have one, but sold it - also to fit it you need to redrill the inlet to fit it (also see below)



Oh, bear in mind, taking a few mm off the standard tb would require you to fit a larger butterfly - taking material off the edges without actually increasing the butterfly size will do nothing - and as no one would make a larger fbw tb for a Clio it would be a pointless exersize.

Also, if you were really determed to fit a larger one, you need to run aftermarket management, as they are a)throttle cable only, and b) do not fit the standard ph1 throttle position sensor, requiring aftermarket mangement.

Dont waste your time and money mate

 

[Dean.]

Megane r26 throttle bodies are only 35mm (iirc), is there a reason they are so small or would it be beneficial to enlarge it??

 

[Russ_16v]

I wil state, techincally you 'could' get gains from a larger single body on a Clio, but you have to do it properly.

As iv said, when I tested the standard inlet (on a friends rolling road) the standard inlet could take more air - but in my opinion you need larger cams with a worked head and aftermarket management (due to the tps) and a very good mapper to get gains.

For the money that would cost, (circa £2500 when you dial in the fitting of the cams, new belt, and mangement) it is much more sensible to go with itb's which gives more power and better driveability at the same price.

 

[Steven103]

I recall reading that the forum consensus is that the OEM throttle bodies are not a limiting factor at all, hence no/negligible gain from fitting one with a bigger diameter.

 

[Russ_16v]

I recall reading that the forum consensus is that the OEM throttle bodies are not a limiting factor at all, hence no/negligible gain from fitting one with a bigger diameter.

Kind of.

You would be able to get a gain if the manifold was better - the way it is the manifold is the largly limiting factor in my own opinion, hence why itb's usually get good results - my own home brewed itb conversion gained me 37bhp and 15lb ft of torque (with an increase of torque circa 25lb ft more from 2500 rpm up) - that is a pretty good gain for a n/a engine with just a inlet system change, so rather than waste time with the standard tb, it is the manifold that is worth looking at - hence also why JMS's inlet conversion uses the standard tb

 

[Steven103]

Sorry, uselessly (lol) late post. Tabbed browsing = distractions = out of date topics by the time you get to replying. Interesting to hear your experiences though Russ.

 

[Russ_16v]

lol no worries mate

Yeah I looked long and hard at it, but for me, it just didnt offer the gain for all the work required - Id rather look at the whole issue - matched inlets help as they are generally cheap enough to do, but in general (imo) the standard inlet is the limiting factor on n/a engines.

Turbo/supercharing is a bit different, as sheer force can overcome the long inlet route, but without a turbo id say junk the inlet for good gains or just get them matched and leave it as that