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MG MGF Technical - Change of throttle body - the outcome
|Following our earlier discussions of this matter, I can now report back on the outcome of the swap of throttle body that I have done on my VVC-engined Elise 111S with a K&N panel filter.|
First of all, a word (or two) of warning: my findings relate to my Lotus Elise. They may not be entirely relevant in the MG F application. Moreover, it must be said that in various Elise circles and bulletin boards voices have been heard which warn of the possible inability of the MEMS, even on the VVC engine, to provide enough fuel at full throttle to cope with the enhanced breathing. If this is the case, the engine will run too lean with all the nasty consequences that this could entail. If you have a 1.8i, I would definitely double check that your fuelling is up to it, before doing the swap.
Right, having said this, what about the result?
Yes, it's really great! The power gain is very clear from about 3500 rpm and becomes truly stunning between 5 and 7000 rpm. I would guess that I have at the very least 10 more bhp. Torque is also better with the car pulling stronger already at 2500 rpm. Induction noise is up slightly too in a really nice and throaty way. Throttle response is also enhanced! What more can I say? It seems to me to be the ultimate upgrade for VVC engines: easy to do (and to undo), discreet (looks like the normal aluminium TB), almost legal (in the sense that, with your cat still on, you will pass any MOT easily) and providing real power gains!!
Are there any drawbacks? Honestly, the only one I have noticed may be that city driving may have become a tiny bit more jerky. Maybe this is because I have on purpose adjusted the throttle cable in such a way that it has a tiny bit of slack in the closed position, in order to really make sure that it always closes completely. Maybe the very slight jerkiness is also linked to the more noticeable fuel cut-off on a trailing throttle above 2000 rpm, although I'm not sure there is that much more fuel being injected at such low rpms...
In any case, I am really happy with this new TB and I can stronly recommend it for all VVC-engined cars. Regarding the issue of there being greater risks of HGF on more powerful K-series engined cars, I guess only time will tell...
thanks for your report. Now I know what I want for Christmas.
|For those who missed the earlier thread on this matter, the TB I used is the one from the MGF Trophy, part number MHB 000261.|
|£112.50 plus vat|
|Mines on order with PTP (3 weeks lead time from MGR) - £98+VAT. My dealer quoted 130+VAT.|
|Hi Per, Thanks for the feedback as this is a further mod that I'm looking at. I currently have the VVC with obligatory K&N, MS Daytona, FSE Boost Valve and a tuned SuperChips RACE Chip. My car was set-up on the rolling road and has 159BHP (148) at the wheels, with peak torque of 136lbft (124), before the ICON installation and setup in brackets. |
I was looking to perhaps install the enhanced exhaust manifold and TB to try and flatten and enhance the torque curve on the RR, therefore this could be really interesting. It is interesting to see that you find that the low speed driveability has decreased as I also find this with mine although with the standard TB, as the car doesn’t like the low revs as much and will judder. I must add though that this is a very mild issue when compared to the huge power gain over standard. :)
PS You can the original post on my car in the archives under “WOW 159BHP at the wheels” as there are some links showing the SuperChips before and after PowerPlots.
|>>>Regarding the issue of there being greater risks of HGF on more powerful K-series engined cars, I guess only time will tell...|
This mod is extremely interesting, Per. What do people think are the likely risks of this sort of mod knackering a 2001 VVC? If it's reasonably safe, then I may be following your example!
|Hi David, Hopefully I won't suffer HGF however I just got my car back today from MGR having had the new enhanced Head Gasket installed with the steel dowels, etc... They also changed both manifold gaskets, etc. and I get a 1yr guarantee on the HG failing! Which was not bad for £430 Inc VAT! :) |
|Thanks for the encouraging report Per- the first time I've heard of anyone fitting a Trophy TB to a non-Trophy car. Great to hear such a positive result! :o)|
This corresponds nicely with the impressions and experience that Dieter and Carl have documented with the even-larger diameter GM TB.
Bearing in mind that the MEMS used, certainly on the original batch of Trophy 160s, is identical hardware-wise to the VVC- I can't see that there would be a problem using this TB, Per. If you visit a Rover or Lotus specialist with access to Testbook, the fueling map could presumably be interogated and modified? From Roger Parker's experience however, the MEMS should easily cope with the altered specs- he has an original MEMS on his 1.8i running a standard TB but on a cast VVC-like inlet plenum and a ported cylinder head with larger valves. This combination I am sure would be far more demanding on fueling than a slightly larger TB alone?
Thanks for the feedback. I had understood that the fuel map that the MEMS has been programmed with is locked and that there is no interface that would allow a user (not even a dealer with a Testbook) to alter it.
However, the experience of Roger Parker that you mention is interesting and I, for one, certainly hope that the MEMS is up to it! I'll keep my fingers crossed and "que sera sera"... ;-)
|Per, you are right regarding the programming of MEMS. But I have *heard* that there are versions of Testbook (or perhaps were certain security protocols are satisfied) that ARE able to alter certain aspects of the map.|
Unfortunately, this is not substantiated information- just hear-say. BUT interesting food for thought don't you think?
|A throttle body for only £112 plus VAT. Seems too cheap. They are normally £400 plus. Am I right are you saying that i can get one from a Rover dealer and fit to a 1.8I with out any other changes or bits to buy? If so I am interested.|
|what's more interesting is they are made in Italy by Delorto ... now how about new throttle body plus ITG ... nice combo ...|
|Multiple throttle bodies (MTP) are sold as kits for circa 400 quid, so the price of the single TB seems about right. From what Per says, the Trophy TB is a straight swop; even the butterfly cam is identical Steve.|
Gaz- Trophy TB + ITG- now there is a Christmas gift I'd love for Santa to drop down the chimney for me :o)
|Just to confirm what Rob said: It is a straight swap! Every bolt, cable, hose and wire fits just like on the original. I even managed to re-use the funny clip holding the air filter hose to the TB. Half an hours' work on an Elise, probably a bit more on an MGF with that body crossbar in the way.|
|>> Gaz- Trophy TB + ITG- now there is a Christmas gift I'd love for Santa to drop down the chimney for me :o) |
Yeah same here Rob. When I placed my order with PTP they already had 15 on back order so I'm down the queue (that was on 28th Nov). They don't expect to get any until mid-Jan. If only I didn't have to shell out for new rear tyres I'd go for the ITG ... waiting game ... its always a waiting game ...
|David, the later cars are fitted with the improved gasket and dowels which should hold together better than the earlier cars.|
|Do they fit the 1.8. Can I just order the TB and Gaskets and fit. Nothing else required?|
|>>If only I didn't have to shell out for new rear tyres I'd go for the ITG ... waiting game ... its always a waiting game ...<<|
I know EXACTLY what you mean mate. For me, the insurance is due next month, otherwise I'd be asking that nice Mr Satur for a shiny new Sprint exhaust system, plus a few other bits and bobs. Oh well. The TB will have to wait... the waiting game.. always a waiting game...
|Rob, have just the thing for your stocking this Christmas, the Trophy rally car featured in last issue of MGW, this has come up for sale.Speak to Santa!!|
|>>Speak to Santa<<|
And maybe a couple of debt counselling services...
|You know, I was reading through that very article last night- sounds like a very interesting car that should be quite easy to convert to circuit racing...|
Bad news though- we're buying a house, so circuit racing budget has just been reappropriated :o(( Nuts.
I've been a very very good boy this year....
o<:o)> (<-- that's supposed to be a Santa smiley in case anyone is wondering!)
|Looks more like a carrol singer....|
|Does this mean I'm insane, Doctor?|
|>>Does this mean I'm insane, Doctor? <<|
Oh no you're not!
Well, it is the panto season! ;o)
Rob, if You buy the rally-car could we look forward to a REAL story in any magazine ? I have always liked MGW for their good tech. articles but IMO when they had the chance to further examine a rally car with probably all the refinements we all look for they do severly fail ! So many years after the intro of that rally-car there can be no big secrets left. Info about cooling system / suspension etc. with some pict would have been nice. The "Chalk and cheese" one was better - but where did the supposed torque-chart for page 43 go ??
Regards , Carl.
|>>>From Roger Parker's experience however, the MEMS should easily cope with the altered specs- he has an original MEMS on his 1.8i running a standard TB but on a cast VVC-like inlet plenum and a ported cylinder head with larger valves<<< and ITG.|
Indeed this self correcting fuelling is also the experience of K series development engineers. The system is self calibrating to a point within the confines of the original map. The airflow and general operating conditions are to be expected to change as the engine ages and as such these variations have to be catered for. This is where the 'flexibility' built into the standard system comes into the frame. There is always a limit to this and I am pretty sure I am close to it. A friend with a modified VVC engine in his car has significantly more power and has also not yet 'run out of fuel' and it doesn't feel to be as close to the limit as mine is.
However time doesn't stand still so my VVC friend and I both have 52mm throttle bodies to see whether the fuelling can cope. Early testing for the new year on the rolling road.
Another aspect to be examined will be the standard fuel pressure regulator. The MEMS systems run at a pressure of 3 bar, less the manifold vacuum which will reduce this to about 2.4bar on a closed or nearly closed throttle.
However what many forget to note is that the actual acceptable pressure range for a standard regulator is 2.8 to 3.2bar, through manufacturing tolerance. This difference will equate to about 8% in total fuel flow through the injectors. So lets assume your regulator is actually opening at 2.8 bar. This means that the maximum fuel flow you will see will be about 8% less than another visually identical regulator on another car.
At idle and light throttle conditions where the closed loop control is active then the injector open time is ammended by MEMS to ensure that lambda is mainatined, and emissions are compliant. However on wide throttle openings the lower setting means that you run leaner, or in circumstances where like me you increase airflow into the engine, the limits are lower and the throttle response may have a degree of hesitation of 'flatness'.
This is the principle which allows the FSE to work as it does, but to be honest on the kits I have seen, I see the method of fitting being crude. I am currently following a route which allows the standard regulator to be altered to a slightly higher measured pressure. I do have a feeling that with the 52mm throttle I will actually need this extra fuel.
We shall see.
|> I do have a feeling that with the 52mm throttle I will actually need this extra fuel.|
Vauxhall GM throttle (57mm !!) as well waiting for your FSE experiance ... *g*
I still wonder why you all pay loads of money for the Trophy part.
So easy to convert the GM (IMO) ;)
|Hmmm........i hope thats a MGF not a V2 your working on there Dieter. I am worried that you may have Liverpool in your slights. Mind you if there is some MGF in the mix i don't have to worry!|
|>>> I still wonder why you all pay loads of money for the Trophy part.|
So easy to convert the GM (IMO) ;) <<<
1) getting the GM-part
2) knowing that it is in a good health (when it is second hand)
3) modifying it
4) trying to get it fit
4 good reasons why I will go for the Trophy part.
Thanks Per for sharing your experiences.
Thanks Roger for your thoughts and facts, I will read them again and again and again, maybe then I will understand a small part of it ;-)
much easier then a spoiler *g*
>1) getting the GM-part >> you didn't ask me:)
>2) knowing that it is in a good health >> (when it is second hand)
>> see No. 1
>3) modifying it >> no 'mod' but just add two brackets and a self made sealing
>4) trying to get it fit >> same as the Trophy,... nearly
Only troubles is to finding any fitting hose for oil sump breather.
BTW.. Carl used to use 'garden hose'... *grin*
|Used Garden Hose!|
Don't give MGR ideas Dieter!
|>> Thanks Roger for your thoughts and facts, I will read them again and again and again, maybe then I will understand a small part of it ... >>|
Glad I wasn't the only one ...
|Sorry if I lost you, essentially I am saying that there is a quite wide degree of automatic adjustability in the standard systems which will cater for production variations between different engines and wear through the engines life. |
The point on the pressure regulator is that they have a mechanical operating setting which, because it is mechanical will vary. In addition being as this is a spring setting over time the spring will weaken and so operating pressures will fall. For emissions this is accomodated with the 'self calibration' of MEMS, but when you go wide open throttle and have an engine that breathes better then a higher pressure setting on the regulator is ideal. The reference to the 2.8 to 3.2 bar for the standard regulators is the pressure range standard MEMS is capable of coping with and providing the normal expected performance, economy and emissions.
Hope this makes it a little clearer.
|Ok, so a better way than the mechanical fuel regulation of the so called "Power Boost Valve" would be to adjust the existing system to use a higher fuel pressure. This sounds interesting but why has no one tried this yet? |
When you say it is a mechanical adjustment, does this mean that it can be adjusted without interfering with the MEMS (within the permitted range, naturally). If so, how do you do it?
Merry Christmas, I'll go for the GM unit if I can get the dosh together.
it is well known between the "DIY-ers" that on most (but not all) fixed pressure regulators there can be a tweak made by fitting a washer or any other suitable thin spacer under the standard spring to increase spring pressure and as a result of that also fuel pressure. The most convenient way to do this is to incorporate a M4 or M5 -type screw and make the thing adjustable . Just as the original FSE-system . But maybee a little more crude and some DIY-ing involved that may not be avaible to all.
Merry Christmas and a Happy New Year,
|>This sounds interesting but why has no one tried this yet? |
Tony, the existing is not so easy to dismantle. (IMO) Did it together with Nikolaj when he got his FSE in the other month
Pictures under point 4 and point 5 show my dirty hand :)
(http://www-users.rwth-aachen.de/nikolaj.klingemann/mg-f/pbv/regler3) As Carl mentioned it sounds all a bit 'rude', no adjustment experiance possible.
|Ok, so what's wrong with the power boost valve then? Surely this will still improve things even if it's not the ideal solution. What are the practical solutions? Put that V6 down Roger....|
Sorry, but I'm a little out of my depth and am trying to learn how to swim.
|is it possible to install the throttle body on a Trophy 160? Would I get more power, or would it be too risky to try?|
you mean the Vauxhall throttle body ? or the power boost valve ?
From my knowledge the inlet flange for the TB is the same and as well the PBV is.
We still havn't seen any test results from any upgraded MGF. So each comment is only individuell feeling currently... and I and some more feel very good :)))
Just try yourself. I daubt there will be any risks regarding the different Engine ECU.
BTW. Trophy ECU is different to the old MEMS, is it ?
Am not really sure whether to try messing with my trophy yet, only 3 months old... would probably invalidate the warrenty, however,, I am interested in seeing what performance increases can be gained from the standard tuned VVC., the trophy is very noticably quicker than the 1.8i I had before, dont often get "bullied" on the roads now!!!!
I have read a lot about how poor MGR cars are. but I have to say, since owning my first F from july 2000 I havent had one problem!! The 2 ford cars I had before were just a complete nightmare,, always something wrong, and always big bills!!
My first F was a company car,, I initially wanted an MX5, due to reliability, but beings that my boss was paying,, I thought I'd try out the F,, I liked the looks more, and it is british. I, like everyone else who just hears stories about how bad these cars are built was expecting to be back and forth from the garage!!!!,, but,, no,, not a single problem,, and the mfg trophy I have now, I payed for it myself,, so I no longer believe the "myths" about how poor MGR build cars.
This thread was discussed between 19/12/2001 and 29/12/2001
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