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MG MGF Technical - Change of throttle body

On the Lotus Elise BBS, there have been some reports recently of people replacing their original throttle body with the bigger one fitted to the MGF Trophy (part number MHB000261). They say it was very easy, took just a few minutes and made a big difference!

Apart from Dieter's change to a GM item a while back, I haven't seen any similar reports here. Has anyone tried this and, if so, has it been a big improvement? I would be particularly interested in perceived changes on a VVC engine.


Hi Per,
I did some time ago write about it and also performancewise gave info from findings on my VVC.
No takers... Hit by the "not invented here syndrome " Assume it floats around in cyberspace or in the archive :)


In the current issue of the MG Car Club magazine "Safety Fast" there is an article about possible changer to the regulations for MGF racing. There may be kits coming of modifications to road going 1.8i and VVC cars to enable them to be on an equal footing with the 160 Trophy I think this is so that they can all run in the same class.

It may be worth waiting to see if the throttle body change features in these kits. If you register as a competitor you will probably get a discount.

David Witham


I just found your thread from a while back in the archive ("GM throttlebody on VVC..."). Interesting observations!

However, you wrongly state that the Trophy throttle body is the same diameter as the regular one. This is not true! It is 52mm inside, i.e. a few milimeters bigger, while being almost identical on the outside, thereby making the swap dead easy as well as highly worthwhile!


Hi Per,
Yes, found out about the error almost immediatly after I sent the message... Anyway - the swap is well worth the money and effort if Opel or original Tropy body doesnīt matter ! There are pict. on Dieters Tech site from my installation.
The swap for Your unit will be even easier as everything will fit without too many alterations. The GM-body needs a bit of DIY but is dead cheap from any scrapyard.. The debete is ongoing on the Elise tech site, some do not belive in it - probably because it doesnīt cost an arm and a leg and is hard to find at some Gandalf-type engine guru :)

Best of luck , Carl.

if its the same diameter outside - would it not be possible to open the origional throttle body up a few mm ??? and replace butterflies etc ?

I'm sorry, I suppose it was me who stated wrong about the Trophy diameter.

So they made it bigger :)) WHY ? .... ROFL...

he, he, ... now I know from 'official' that the Vauxhall, GM, Opel body was the best and cheapest I did to my car ;)

My MPI goes under current cold ambient temperatures up to 6200 revs an a flat motorway. Downhill more :)
Dyno measurement still delayed, but I'll go as soon as I find a cheap place.

Dunno how much followed the installation to the MGF until now. It is me, Carl, Nikolaj, Matthias and Jens.

If somebody likes one (non reworked) for own DIY than let me know. I can't promise availiability but put you on list of interested for a working but 'dirty' looking second hand part including a brand new but mild steel ball joint to attach the cable.
Gimme your quote by email :) How much is it worth ?

At last
- four holes to make longer (+1.8mm) with a file
- rubber sealing to be cut to seal the body and the intake manifold from air leaks
- flange plate for the throttle sensor to be done from 5 mm Aluminum plate. two of 3mm work as well.
- two wires at the connector to be swapped
- bracket for throttle cable to be done.
Bolt off the old, bold on the larger. Adjust the sensor. (Resistance measurements recommended)
... wrooooommm ...
Carl, did I forget anything ?

>to open the origional throttle body up a few mm ??? and replace butterflies etc ?

Tony, not worth to think about, but I can sell a second hand plasic crap thing for own tries.

Dieter Koennecke

>>>It may be worth waiting to see if the throttle body change features in these kits. If you register as a competitor you will probably get a discount<<<

They may well be a feature, but don't expect to get any discount without production of a current RAC race licence.

The larger throttle provides a potential for an increase in the peak airflow that is able to pass through it. If the original throttle size is actually a restriction then reducing that restriction will enable a greater peak power to be achieved. Also at all other openings the potential airflow through the throttle body is greater and this can lead to a situation where more power is generated at a given throttle opening, subject of course to the correct fuel and ignition timing.

However the adaptive nature of the MEMS helps to cover this quite adequately. Clearly though the main benefits comes on larger throttle openings and more so as revs rise.

Anyone thinking of the change should note the correct part number as shown by Per and be sure this is what they get. There are two other current metal throttle bodies listed!!!

Roger Parker

PTP are selling the Trophy 160 throttle for Ģ 98.00 if anyone needs one, My main Rover dealer wanted Ģ 116.00 quid. I found the car to respond better but have yet to put it on the rollers,
Steve James


the PTP price looks good, but see the measures below.

Diameters of availiable parts:
Mk1 plastic until VIN 1D522xxx is 48mm
Mk2 metal since 1D522xxx is ???
Mk3 Trophy 52 mm
Vauxhall/GM/Opel is 57 mm :))) and it has needle bearings :)))

Can somebody confirm and/or add the Mark2 diameter please ?
Dieter Koennecke

Dieter, how much for you to come to Holland and help me fit it :-)
Tony Smith

*g* it is so boring for an engineer to make things twice... ;)
Gareth wanted one and Rob as well with a 'may be'). Now you as another good mate. These three are currently the stocked.
Anyway, I need a new Camera, so at first cash and than fun. Please wait with patience, I booked you in. Will get 'social' cheap in any way.

PS any news about Cor V. ?
Dieter Koennecke

Now what would my insurance company say about this mod :-(
Tony Smith

No quest will be no answer :)
Nobody will see any difference, cause it looks professional.
Dieter Koennecke

If I had the money I'd flog the F and get a TVR Tuscan. So if the lottery god is listening....
Tony Smith

I have now received my new throttle body :-). Quite apart from the performance boost I expect it to give, I must say that it is also a beautiful piece of precision engineering! It is fascinating just to sit and play with that big throttle butterfly. Incidentally, it is made by Dell'Orto which brings to mind images of outrageous Italian supercars from the past. But I digress...

I actually have a question: I want to make the swap in a very discreet way, i.e. I would like it to look as if it is the factory fitted TB. Therefore, I would like to keep the original worm clip which attaches the rubber hose to the TB without any screw. Does anyone know if it is possible to remove and refit that clip or does it get destroyed when you remove it? In that case, do MG dealers have a special tool to refit a new clip of that kind?

Thanks in advance for your help!



Surely, all the people who have fitted K&Ns onto their cars must have come across this issue...?


I was unable to preserve the clip and had to use a worm one.
I suspect they are a one-use clip on the original.

Hi Per,
it is as You suggest - a special tool BUT can be opend with a screwdriver (slightly bending open ) and closed with a poly-grip (using the foremost part of the polygrip to put some tension to make the "lock" engage again) . A bit difficult first time but tends to improve with number of times done !

Regards , Carl

Thanks guys, I'll have a go at it, and I'll keep you posted on the outcome.



>>>Mk2 metal since 1D522xxx is ???<<<

MHB 000080 believed to be still 48mm.

The original clip can be refitted with some perseverence with a pair of long nosed pliers.

Roger Parker

I take it this is the throttle body manufacturer ...

Scroll down until you see the TV code.


wonder what problems you got. ;)

The factory clamp can be attached back without any problem.... if you understood how easy it works.

Try it at first with no tool, just in your hands to see how it works. Than to the body with hose and heckle it on.

BTW. has the expensive original body as well needle bearings at the flap axle ?

Dieter Koennecke

direct link is :
(in italian)
I guess Per's is the TV5 (dia 52mm)

>> Does anyone know if it is possible to remove and refit that clip or does it get destroyed when you remove it?<<

As the guys say Per, it is possible to remove the clip without damage with a screw driver and re-fit it successfully afterwards.
Have you made the swop yet Per? What do you think?

I saw Dieter's GM TB mod in the 'alloy' recently- and was impressed by the neatness of the installation. Dieter has kept the original 'non-linear' butterfly valve cam which slows initial throttle openings, but rams it open with greater pedal movements... should make for smoother travel in traffic compared to the more linear cam found on the standard MGF TB. How are you finding the car to live with Dieter?
Rob Bell


I haven't done the swap yet, been quite busy lately. I'll let you know how it feels when it's done.

As Gaz and Fabrice indicated, the TV5 body is the relevant one. Although my school Italian is a bit rusty, I interpret "comando a camma diretta progressiva" as meaning that the opening is not linear but is done through a progresively shaped cam. Looking at it, I must say that it looks quite circular and "unprogresive" to me, but we'll see when it's on...


A friend has done the 160 TB swap on his Thielert 150 upgraded Elise. He reported that it took 15 mins to change & the throttle response was a lot swifter. It was a direct replacement, whereas the GM one needs a bit of fiddling with IIRC. He's a very happy bunny now anyway.

BTW, I agree with you Per, it is a thing of beauty :o)

Hi Rob and all,

unfortunatly I think itīs the other way around. (Canīt check as I am not at home). Faster opening in the beginning and slower at the end of opening the flap. Thatīs the reason why I simply reworked the things to get a more linear response.
I once had this response on a Porsche (add on thingy made by previous owner ) but never got on terms with it - especially not on the track and slalom events

Apart from that I can fully recomend the swap :)

Rergards , Carl.

Slow at the beginning and fast at the end is the opening behavior of the large GM throttle flap.

I can't state anything to the response sensitivity...
It's much better than before, special in the mid range of revs (2500..5000).
At higher revs there is no feeling IMO, cause there nothing more to speed up at our small K-Engine :)

Anyway, I do each weekend 100miles from home to work and back. One quarter in top speed (I'm sorry !!). The car gets now 6.300 revs on plane motorways under current weather conditions and if the road is DRY. Uphill less and I bother trying top speed downhill. That's enough for me :)
Did no comparison run with any other F until now. :(

Oil temperature seams as well lower than before, but it can be an error due low ambient temperatures and the replacement of the open K&N to a K&N panel filter with short hose from the filterbox downwards to the air inlet. Isn't 130° C at 5500 to 6000 revs a nice value ? :))

Dieter Koennecke

Carl, Dieter mentioned that you had modified the GM throttle cam! Just thinking about it now, that cam would confound any subjective impression about responsiveness from the TB change, but since others report favourable changes in throttle responsiveness with Trophy TBs and this matches your experience with the GM TB with a more linear throttle opening is very encouraging.

I'd love to undertake the swap- but there are other deciders, such as buying a new Mk3 MGF when it comes out, keeping the current car for sprinting, or buying another (!!!) for racing leaving me free to play with my current car. Oh choices choices... ;o)

Dieter, I wonder why oil temperature should be so sensitive to intake charge temperature/ TB throttle diameter??? Is there something about the positioning of the oil temp sensor location?
Rob Bell

Price must have gone up 112.50 + VAT from the Hampton dealer ...


But, only but and doubts... *g*, mate you've been to often for visits in germany ... ROFL.

Carl only removed one moving part and replaced the sliding joint with a ball joint. Easiest mod.
Original GM
My near to the original version

The milling works he did to get space for parts with lack of clearance can easy be done with the hacksaw and file.
(Don Liang will of course use a Laser to cut *grin*. Don do you read ?

Required hoses can be used from pieces of any garden- hose (fitting diameter).

Two positions at the throttle sensor to be swapped, one aluminum flange plate and one aluminum bracket.
Updated the site the other week for Don's questions with some more details.

Wanna see a throttle body test articel in MG World before next Silverstone meeting.
I think you need one than.
Going back to the plastic is easy works and can be done quick if you keep the dismantled parts.

I see I need to complete the TB at home with brackets and joints. After christmas, Promised.
Would 50 quid be OK ?
Dieter Koennecke

Definitely Dieter! ;o)

BTW expecting to return to Germany a few more times this comming year! :o)
Rob Bell

This thread was discussed between 09/11/2001 and 30/11/2001

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.