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MG MGF Technical - Engine tuning.

Hi guys,

I've two little questions.
I'm driving an MG-F 1.8i VVC, year 1997, and I did a few modifications on the engine.
- revised engine (after belt-failure)
- gasflowed head
- head skimmed
- cc-ing job
- portmatched
- modified valves
- magnecor ignitionwires
- splitfire sparkplugs
- K&N filter
- Tenzo Racingsports airpiping to bring the filter to the side opening.

Now I'm planning my next step, and I think new cams are the best move now (?). But i want to do more. I'm thinking of also doing the MEMS and changing the throttlebodies to Jenvey throttlebodies.

Is this a good choise or do I have to do other things first?
How far can I go without making it neccessary to change the crank, conrods and pistons?

Thanxx in advance.
Greetings, Jan.
Jan

Jan,

Your biggest hurdle here will be the VVC mechanism. With this in-situ you'll struggle to find a replacement ECU, certainly the ever popular Emerald is not able to cope at the moment (though there may be one in the nearish future) though there may be another developer with a suitable unit but this will come at a huge cost. Typically in your case the next stage is to ditch the VVC mechanism in favour of solid cams, Jenvey TB's and an emerald. This will return some very respectable results, with a large valve, ported VVC head this could be up to 185-190bhp.

However with your current modifications the next step if you want to retain the VVC mech is to replace the Exhaust cam for one with slightly hotter timing. Dave Andrews is the man to quiz about this. www.dvapower.com

Of course one other modification which could be considered in a decent 4-2-1 manifold, this would release a little bit more mid-range torque.

As far as the bottom end is concerned, the K-series is able to cope with a decent amount of power before considering forged pistons and crank etc.... if considering anything in the order of 190 it might be a good idea, however convoluted exhaust tract is the thing which restricts the ultimate top end perpormance of the car. Dave Andrews has developed a K-series engine up to 250 bhp (this was a race spec 1.7 engine Mmmmm) but this was in a caterham with a lovely straight exhaust.

Any way this gives you a few things to think about. Do you retain the VVC or ditch it in search of the ultimate naturally asparated performance engine!?

Tim
tim woolcott

Hi Jan, the engine sounds like it is coming together really well! :o) I agree completely with what Tim has said, and as he's going down similar avenues to you (as has Dave and Kingsley) he is a good person to listen to :o)

>>Now I'm planning my next step, and I think new cams are the best move now (?)<<

Yes, I'd agree with this. Exactly what you do next is dependent upon exactly how far you want to take your engine.
I'm guessing that with your car's current spec, you've got somewhere in the region of 170 bhp? An exhaust cam, keeping the original MEMS and VVC should see a few more bhp added to that tally for not too great an expense, but if you want to break the 180 bhp/ 100 bhp/litre barrier then something a little more special is required.

>>But i want to do more. I'm thinking of also doing the MEMS and changing the throttlebodies to Jenvey throttlebodies.<<

And this sounds exactly the way to go. You'll need a Piper cams kit, with blanking kit to replace the VVC, a re-programmable ECU (most seem to go for the Emerald M3D) and direct to head throttle bodies (Jenvey, as you say, are probably best). Add to this shopping list, Bernard Scouse's excellent airbox and throttle linkage (that also retains the standard fuel rail - clever)and you'll be away on the engine front.

>>Is this a good choise or do I have to do other things first?<<

I think that Tim's suggestion of paying attention to the exhaust extraction is very sensible: a decent 4-2-1 manifold is a must for optimal power, along with a decent exhaust back box. You might even consider a replacement sports catalyst (or even cat bypass tube, if you are permitted).

Then there is the chassis and brakes to consider: the standard brakes are particularly poor, and really ought to be one of the things you sort out first.

>>How far can I go without making it neccessary to change the crank, conrods and pistons?<<

With a 7500 rpm limit, you'll probably get away with standard parts, but for optimal power you'll probably be wanting to increase the rpm limit to above 8000 rpm - and at this point, the engine internals will need upgrading. Consider too a stiffer bearing ladder and block flex may also become a problem...

Good luck Jan - and keep us posted on progress! :o)
Rob Bell

I'd leave it!
170bhp has got to be enough!
spend the money on brakes and handling that'll improve your cars performance far more significantly.

If you must get more power then a loud straighthrough exhaust and a cat bypass pipe will get the last out of it and make the thing sound a whole lot quicker too.

I wouldnt dump the VVC. you are looking at serious money to get anything more out of it. concentrate on the things that make it really faster. Brakes tyres, bushes suspension etc
Neil

I don't understand something.
Why do I have to get rid of the VVC meganism?
It's possible of tuning an B18A DOHC engine (Honda VTEC) to 650 bhp with remaining the VTEC system.
The VVC system isn't that different, I thought..?

By the way, the engine isn't the only thing I've modified.
For anyone who's interested...

Styling:
- Car restyled and partly resprayed
- Trophy style front spoiler
- Polished stainless steel grilles
- Polished stainless steel aerial
- Smoke side and front repeaters
- Red/smoke rearlights
- High level stop light
- 40 mm lowered suspensions
- Union jack labels
- Titan-wood dashboard
- Tenzo Racingsports Pro 5" Tach White
- MOMO gear knob
- Polished stainless steel door tread plates
- Alloy door button escutcheons
- Windbreak screen
- MG badged rubber mats
- Removed wheelarch rubbers
- Custom made alloy spacers 25 mm
- 17" Avalini Jet rims
- Toyo Proxes T1S Tires 205-40-17
- MG tire valve caps
- Original MG-F VVC rims for the winterdays
- Black hardtop for the winterdays

Tuning:
- Complete revised engine
- Ported and gas-flowed cylinder head
- Portmatched intake and exhaust ports to manifolds
- Chamber cc-ing job
- Skimmed and resurfaced cylinder head
- Painted valve cover
- Blue performance hoses
- K&N 57i air-inductionkit
- Tenzo Racingsports intake pipes
- Small K&N filter
- Magnecor competition ignition leads
- Splitfire Premium spark plugs.
- Super Sports exhaust MkII
- Cat by-pass pipe
- EBC green stuff brake pads
- EBC front turbo grooved brake discs

Ice:
- Enough to make a lot of noise :-).

Lester side-skirts are ready to be placed now.
The Pro 5" Tach should be connected well soon.
Jan

VVC is quite different to the Honda VTEC Jan, insofar as it isn't a case of two separate cam profiles coming in at different rpm: the VVC is continuously variable.

Unfortunately, the VVC mechanism isn't quite as strong as Rover's engineers would have wished for - and significant research was commenced to improve the material performance of these cams. Unfortunately, this research was stopped during the BMW years, as effort was concentrated on the NG4 engine (made at Hamm's Hall). Since BMW and MG have gone their separate ways, research has restarted on ways for improving VVC performance, but nothing has yet surfaced.

Bottom line is that the VVC can become unreliable if pushed too far. This, combined with a lack of a re-programmable ECU for controlling the VVC mechanism means that most tuners choose to replace the VVC with more conventional cams :o(

However, you can keep the standard VVC, and replace the exhaust cam with a Piper 270 - and this should yield some promising results :o)

What kind of power output are you aiming for Jan?

BTW, as Neil emphasised, a very good idea to really upgrade the chassis and brakes: EBC pads don't really tolerate serious performance :o(
Rob Bell

I'm looking for at least 200 bhp.
(I also thought about a 50 bhp shot of Nitrous Express, but that would be a bit tricky for my engine I think.
I like bhp without cheating with Nitro better!!)
Jan

Jeez...sounds very costly!
but I see no mention of big four pot brakes!
if you have already invested in big wheels then you should go and get a set all round. Hi Spec do a good set that will work!

If you have money to burn there are ways and means of extracting monster bhp from the K series but it has to be said they are non VVC ones!

turbochargers from BBR others have superchargers or some of the really radical engineers Janspeed got 600bhp from a K series (1.4 ?) for the Bonneville salt flats record car

or of course there is the valhalla of performance
the K2000 race engine...if you do only a few thousand miles a yeah it'll last years
Neil

200 bhp is quite achievable: what is your budget, and do you fancy forced induction?

215+bhp and a huge wadge of torque is available with the turbotechniques conversion. Power comes in well before 7500 rpm, so altering all the engine internals is not strictly necessary. No cam change either! See the Turbotechnics website: http://www.turbotechnics.com/

It's proven to be pretty reliable, as the Lotus Elise owners will tell you (same engine as ours!). Only down side is a bill of close to 6000 UKP
Rob Bell

This thread was discussed between 29/12/2003 and 30/12/2003

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