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MG MGF Technical - VVC RR - interesting result

Took my 96 F VVC to Southern Carbs for a power run on their RR this morning. Very pleased with the result - peak power was 162 bhp at the flywheel at 7000 rpm. Peak Torque 129 at c5200 rpm. Mods for those interested:

* 52mm TB
* Janspeed 4 2 1 manifold
* M'tek Supersports silencer
* Motobuild "rice cooker" cold air box / induction kit with Piper Cross cone filter.

Have thought about the DVA 170bhp kit but have heard mixed things about whether you can run properly with the standard ECU and the uprated camms. Seems a lot of money for an extra 8 bhp. Any views? Perhaps just a little light porting?
marc h

Talk to Dave Livingstone - 175 bhp from his DVA ported head, and the thing just pulls like a train! :o)
Rob Bell

But is that 175 starting from a 160 TF or from a 145 VVC F? And does that include uprated silencer and induction / filter kit? In other words, as Ive got the TB, filter and silencer upgraded already would I only be buying myself 8 bhp or would I be buying myself 20 bhp? Would ask Dave Andrews but when I last spoke to him he didnt sound terribly interested...
marc h

Starting point was 145bhp. Dave's also got a 52mm TB, an ITG and a Phoenix exhaust. He'll be getting a Powerspeed 4-2-1 exhaust manifold soon.

What would you expect to gain? Good question.

Remember that your 162bhp at Southern Carbs may not translate well to the power recorded at Emerald. For example, if we believed the figures at G-Force, then Dave's got nearly 200bhp... ;o)

Clearly, sadly, he hasn't!

Do you have the power curves Marc - particularly the figures at the wheels?

Bottom line is that I'd expect you to gain somewhere in the order of 15-20bhp - and perhaps a little more to gain if you upgraded the exhaust cam.

All this lot will run very happily on MEMS2J. :o)

Rob Bell

Having been behind Dave as he powers away up the hill at Cadwell, if someone told me Dave has 200 horses I'd not have disbelieved you... :o] Rob, your reasons for fitting a big fan anything to do with you getting the same treatment? ;-)

Sometimes wonder if the variance between rolling roads is their way of ensuring repeat business, surely it can't be too hard to calibrate to at least a reasonable accuracy?

Go on, port & polish the head... You know you want to... Just matching to the manifolds is a big step towards a smooth air path; then get on a track with some other VVCs, and the sense of your investment will suddenly be plain for all to see ;-)
Mike Hankin

>> Sometimes wonder if the variance between rolling roads is their way of ensuring repeat business, surely it can't be too hard to calibrate to at least a reasonable accuracy? <<

Mike, you cynic you! ROFL

Some truth in that though - which is why it is so important to find a 'good' rolling road.

Southern Carbs have an excellent reputation - so I suspect that they'll get reproducible results, which will be useful for you Marc when it comes to judging performance upgrades.

Marc - I have a vague recollection that SC use a load cell-based RR rather than an inertia roller? Can you confirm? Their website isn't clear on the technicalities of their equipment.

Why is this important? The inertia roller dynometer enables you to perform a 'run down estimate' of transmission power losses. This is what Emerald use - along with the majority of RR in the UK.
The load cell doesn't work in the same way, and instead measures the torque applied to the roller under load, and therefore cannot be used to calculate a run-down of transmission losses.
The only solution for these RRs is to use some complex computer algorithm to estimate these power loses based on previous experience. Essentially, they have to guess what the transmission loses are! "Fudge factor three, Mister Sulu!" ;o) Sorry, couldn't resist that! But seriously, that is how it works at G-Force, using their load-cell RR. Flywheel estimates of power loss were way off. Measured power at the wheels were spot on the money - and almost directly comparable to what we see at Emerald (our usual Gold Standard RR).

As with any measurement instrument, there are pros and cons. Load cells are extremely accurate (more so than an inertia roller) and are capable of providing highly reproducible results, but to estimate flywheel power requires a lot of experience with a particular model.
Rob Bell

Hmm I'll have to come up to Emerald next time you go. Im taking the metro turbo to SC tomorrow. As its a standard car Id expect to see 98 bhp. If it comes up about that level does that mean the RR is accurate (ish) or does it vary from car to car? 15 to 20 bhp would be a nice boost. Presumably thats with the new cams? Yes I have the power curve but Im afraid Im very crap at loading these things onto the web. I could tell you the power at the wheels if that helps?
marc h

ps Rob, see my post on the MGCCSC BB.
marc h

Got it Marc.

One area that seems to be a bit vague to me is how the championship handles the MGF and TF. Are they or should they be regarded as the same car?

If they are regarded as running in the same class, then you could consider fitting a Trophy 160 or TF160 cylinder head, which immediately flows a good deal better than you 145 VVC head - and still run in the standard class.
Rob Bell

they have a load cell based rr so youve got me nervous now!

if they can accurately read the bhp on the metro turbo does that mean theyve got it correctly set up? or does it depend on the type of engine (ie you need a special calculation for each type of engine rather than one calculation for all types of engine?) They say they get accurate results for the clio cup cars they test and also the mini miglia cars too.
marc h

Rob,
< He'll be getting a Powerspeed 4-2-1 exhaust manifold soon.>
How is the hunt for the perfect manifold going and the price?.
Andrew Regens

Andrew, I have the perfect manifold on the car as we speak - and I can't begin to descibe to you what a piece of wonder it is! :oD

I need to get up to Emerald for a RR session so I can say definitively where all the gains are - but subjectively (where it's most important I guess) - the gains are everywhere. Pulls harder from idle right up to the top end. I am surprised!!! I've already paid for mine - 450 plus VAT. A group buy would hopefully work out cheaper, but it depends on the numbers wanting one. Plus, Dave needs access to a car fitted with an air con compressor so that he can ensure that the manifold will fit to any car! :o)

>> if they can accurately read the bhp on the metro turbo does that mean theyve got it correctly set up? or does it depend on the type of engine <<

Marc, sorry, I didn't mean to make you nervous. As I said, a load cell RR is an extremely accurate measurement device. The measured figures at the road will be absolutely spot on (assuming that you've got correct tyre pressures), It's only the estimation of flywheel power that will be a little off if they are not familiar with the A-series/ gearbox combination. By the sounds of things, they may well be okay with this if they have experience with classic Minis and will be able to give you a reasonable stab at flywheel power that is representative of the factory dyno figures.


It is worth bearing in mind though that. at the end of the day, setting a car up on a RR requires accurate and reproducible measurement. The actual figure written down is comparatively less important, if you see what I mean.
Rob Bell

Mike, if you want to see an F with a genuine 200BHP on tap, try keeping up with Gerry Hirons Honda powered MS conversion. My VVC, despite its may flirtations with the darkside, cannot get anywhere near Gerrys Honda powered F and annoyingly he drives like a ????.
If you really want lots of BHP the Honda conversion will take some beating, not sure how much it costs though?
Terry

if i want a car with a honda engine i'll by a type r or an s2000. what i like about the f is that the engine and the body are british designed - wont see the like of it again!

rob, what i meant about the rr was that if they seem to get it right with the metro does it mean they are likely to have got it right with the f? or would they also need to be experts in the k series engine? if the bhp at wheel figures are accurate can you then work out what the bhp at flywheel figure would be if you had equivalent figures from a car tested on an inertia rr?
marc h

Okay, I see what you mean. The answer to that is no - the A+ plus engine sitting on top of its 4-speed 'box in the sump with have very different frictional losses to a K-series with a PG1 'box bolted to its side.

Can you use the figures at the wheels and then apply a transmission loss measured at another rolling road? Yes and no. Yes, if you want a rough estimate, and no, because every car is slightly different with a host of different variables at play (e.g. tyres, tyre pressures, final drive ratio, condition of gear box).

Is SC able to supply you with a data file containing your RR results? I could try and 'bodge' a curve to compare with an Emerald result. But at the end of the day, your best bet is to go there yourself. :o)
Rob Bell

ok - next time you go to emerald give me a shout!
marc h

Might be soon - I want to check out the performance of this exhaust manifold of mine :o)
Rob Bell


From someone who has a ported head (albeit in bits at the moment!) I can assure you that the headline power figures are only half the story. The engine is just sweet to drive post-porting.

P.
Paul Nothard

This thread was discussed between 21/06/2005 and 26/06/2005

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