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MG MGF Technical - More power from VVC
|The tuning mods available for the VVC have been limited with most mods being available for the 1.8i...until now, a gasflowed head with uprated valve springs giving a usefull power boost.In addition to this I am looking at reprofiling the VVC cams,something that hasn't been done yet!This meens dismantling the VVC cams although a little complicated can be done.This will give a higher lift and combined with the attributes of the variable valve timing should give the F the extra power it needs.This conversion will only be offered on customers own heads and will be fully built ready to refit.I have no costings or expected power outputs yet as these developments are "hot off the press".These developments have been brought about because of the number of VVC owners requesting more power.Interested owners please comment.|
I am interested - subject to seeing how much power and torque I'll get for my £££.
Any news on the SS down pipes? My cars sounding bl**dy awful.
Trouble is once you've paid for the upgrade, how much more do the insurance bods want? Rules out anything if you have to pay London insurance rates.
Of course if it's invisible to the casual examiner's eye.....
|Some interesting discoveries which could help VVC owners at some time, the VVC cam assemblies are about318gbp each and you need two! I reckon these could be reconditioned with new bearings and seals at a far lower cost than new,of course if the lobes are worn as well then it is a new assembly as the cam is not available separate from the VVC thingy.Because the cams are made by shrinking the lobes to the shaft of the cam(?!)new lobes could be made and fitted,these could be made with higher lift and longer duration for more power!If anybody has a knackered VVC head let me know ,must be a few about!Rover's policy has been to replace the complete head if any problems have occured with the VVC's.Must be a pile somewhere.|
Paul still waiting a delivery on the new down pipes AND manifolds.Try turning up the stereo for now.
Hugh as with any power gains there has to be a loss some where usually this is counted in Pounds.
I have said it before and I'll say it again, PLEASE PLEASE think about setting up in Australia, preferably the West. Some of the ideas you are contemplating doing I would love for my VVC, but we just dont seem to have anybody down under who is competent or interested enough to even think about some of these modifications to our cars. Be it a Holden or Ford you can get what you like, but otherwise just dream and read about it. I had a dickens of a job getting some seat covers for my MGF, in the end I had to get a set professionally made which of course were extremely expensive. Never mind we do have beautiful weather and gorgeous meter maid girls so we cant grumble too much can we !!! Regards Peter H
|In June I fitted a development head from PTP onto a Rover 200BRM for some evaluation work. That included testing that car at Bruntingthorpe at the same time that the Rover 25 converted into an MG concept was also tested. This car has the high torque 160bhp engine and close ratio gearbox and the performance was very close. |
Originally I did some rolling road back to back testing on before the head fit with different air filters. Interestingly the results in the 200 did not follow the pattern found with the MGF VVC air filter tests and the K&N Cone was slightly down on power. A panel filter was best by 5bhp or 4%. This difference should not be interprested as applicable to the F. Of interest we did add a fuel additive (which you can't buy - yet) and saw and immediate additional 5bhp and the throttle response sharpened with it. This lasted to the next fill up!
The head is developed as a spec that could be produced in reasonable volume but at a price, as the mods are labour intensive. The immediate effect, once I solved why the engine wouldn't reach max revs,(6700rpm and on the limiter. Cause was the VVC solenoids were in line when they should be offset.) was to feel a much stronger mid range and less of a transition when passing through 5000rpm. Top end seemed to benefit less.
Subsequent to this the car was fitted with a Janspeed specially made exhaust which was fitted by them and run before and after on their rolling road. The difference was an additional 5bhp at the wheels. The difference in rolling roads would not make much difference to that figure so the exhaust is worth about 4% tops.
Last week I went back to Pete Bugess's rolling road for a few further runs. The average of many runs was to settle on a rock solid additional 25bhp at the wheels over the level of the previous airfilter tests. That is with the head and the exhaust, so the head is worth about 20bhp at the wheels.
The end result is an engine that is approaching 100bhp per litre so is not far off becoming less pleasant for road conditions. Also fuelling is being stretched at this level and any additional power would have to take account of the need for additional fuel by way of another mapped ECU or perhaps an FSE Power Boost valve if that doesn't destroy the superb fuel economy that is still present.
Consideration to matching the ports on the inlet system has been given, but this will be held back until the system I am building is tested to see if it is worthwile. Additional thought has been given to create the Cup style of exhaust manifold where the pipe welding is on the outside and not on the inside where the gas flow is. Two manifolds have been welded up and will be ground out internally. The testing on the rolling road shows a quite considerable heat build up in where the pipes join at the manifold to downpipe.
MIKE - this may add to the effect of the downpipes??
The new spec VVC engine which I understand will be the 160bhp spec, may well feature cam variations as the head mods are not production line suitable, it will be more than interesting to see a modded head on this spec as the fuelling should have some greater flexibility, and the overall engine spec will be poorer than it would have been 2 years ago owning to the current and forthcoming OBD engine managment restrictions. This 'could' provide a window for tuners to gain more, subject to the knock on effect of legislation as it applies to owners.
Enough from me for now.
|Rog,what actual BHP figure are you achieving at the rear wheels? The exhaust manifold is a BIG restriction on power and a new system with bigger primaries will be advantageous.|
The VVC mods I am looking at are new higher lift VVC camswith redesigned profiles in conjunction with gas flowing and matching ports to manifold ,a revamped ECU and some other mods admitedly the VVC head is better ported than the 1.8i and so smaller gains will be had in comparison.The estimated gains in out put will be around 165-175BHP.The exhaust manifold and downpipes are vital to these power gains apart from the fact the std items are not up to the job (IMO)
Peter,send me the air tickets!
|Mike the average of the first set of quite a few runs was 125 at the wheels and this is now averaging at 150. Allowing for a realistic 10% plus 12 losses between tyres and flywheel gives a result of about 177 at the flywheel. The numbers of course are specific to that road only, but taken at face value they do match the figures achieved by development engines that were considered for the BRM 200 models.|
With this specific head I mentioned that the mods are not ideal for volume production as they are quite time and labour intensive. However I have little doubt that this extra work has helped considerably to this pleasing result.
The feedback from 'those who have the test rigs and experience' say that the matching of the VVC manifolding is not worth the effort. I have seen how mismatched it is in standard form and would really prefer to see a negative result from matched manifolds. I have a set not only matched but flowed so this should hopefully give an insight. The other comment that comes from this quarter is that the VVC inlet is reaching it's limits at about 100bhp per litre and then the advantages of multiple throttle bodies comes into their own. With your concept of different ECU this option is one that should be much easier to set up.
|Rog ,I agree that matching inlet ports wil only have a marginal effect and in some tuning applications may have a retrograde effect ,especially on the torque, so your results are awaited with some interest!|
This thread was discussed between 16/12/2000 and 26/12/2000
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