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MG MGF Technical - Converting MPi to VVC

Hi,

I'm Sander Bogers form the Netherlands. I'm new to the BBS but some of you might allready know me from the usual forums. I've owned a 1997 MGF MPi for over 2 year now and I've bought a second car so my F can become a true "Fun" car for the weekend instead of daily transportation.

I've upgraded quite a few things on my F including AP brakes, lowering knuckles and a full powerflex kit. Now it's getting time to upgrade the power :) Currently I have 116bhp (dyno tested @wheels) by using bolt-on parts.

I've allways wanted a VVC head because of the superior valve/throat design. I've received a VVC head today :) I allways thought a (ported) VVC head with a solid cam conversion would be the ideal upgrade form my MPi but now I'm thinking why take out all the VVC mechanics and lose power while doing it. Since the VVC head came with all sensors and mechanics why not try to convert my MPi K-series into a VVC unit ?

Regarding this idea a few questions came up:
- Can this be done ? Has it been done allready ?
- will the MPi camcover fit since the VVC head is bigger ?
- What more except Ignition/ECU and a VVC wiring loom will I need to complete the conversion ?
- Didn't the VVC gearbox use different ratios ?

What do you guys think about this (any thoughts would be nice) ? I thought this would be the right place to ask since all "guru's" seem to post here nowadays ;)
Sander

by cam cover doi you mean cam belt cover?

Yup to all your other q's.

the Mpi gearbox will be more nippy

the head can be lightly ported keeping the MEMS, or really done over and used with an emerald (the new one drives the VVC)

if you use a MEMS you will have to get your hands on the 5AS alarm ECU which matches it or get it reprogrammed.
Will Munns

Thanks for the reply !

With "solid cam conversion" I mean the kit piper makes to remove the VVC mechanics and replace them with classic "solid" cams like the MPi uses.

What do you mean with "more nippy" ?

I'm not really worried about the alarm ECU since a good friend of mine owns a T4 testbook. I think he'll be able to match MEMS with the existing alarm ECU for me :)

What would typically be the maximum power for MEMS to correctly fuel (perhaps running fuel pressure at 3,3bar ?) The Xpower kit give you 172bhp on a TF160 and MEMS seems to cope with this. Or can this kind of power only be achieved using MEMS3 instead of MEMS2 ? Will it be more difficult to use MEMS3 regarding connectors and matchin to the alarm ECU ? I have a spare TF135 manifold does it use the same sensors on it as the TF160 engine ?
Sander

>With "solid cam conversion" I mean the kit piper makes
>to remove the VVC mechanics and replace them with
>classic "solid" cams like the MPi uses.

Yup, but there is power to be had with the VVC head, yes you can get more by ditching the VVC and using wild cams, but then you lose low rpm torque.

>What do you mean with "more nippy" ?

Better acceleration

>friend of mine owns a T4 testbook.

Cool

>What would typically be the maximum power for MEMS to correctly fuel

I think DVA has had 175Bhp with the standard ECU

>(perhaps running fuel pressure at 3,3bar ?)

I wouldn't run anything other than standard pressure unless you can map the ECU (I don't think the early MEMS are mappable)

The things you need to match are, ECU, engine loom, MAP sensor, keep as many parts from the same car, the easiest interface to match is the car to engine connector as it has the samllest differences between the car (any diffrences?)
Will Munns

Welcome Sanders ;)

>>> I have a spare TF135 manifold does it use the same sensors on it as the TF160 engine ? <<<
I am sure the F VVC engine has the MAP sensor on the manifold itself, while the sensor at the MPi version of the F, is located at the ECU/MEMS. How is this arranged on the TF's ?

Why would you go for the Rover ECU, while there is an Emerald able to operate the VVC mechanisme ?
Erik

>Why would you go for the Rover ECU

Because it's free and a better (if less flexiable) ECU.

The emerald is a fairly dumb ECU, but it's great if you want to control non-standard changes, or see sensor outputs. As he has a friend with access to the testbook I would keep with the MEMS.
Will Munns

Hi,

<.. What do you mean with "more nippy"?

Better acceleration ..>

I hate to be nit-piccy (well, sometimes it's fun) but the Mpi has a slightly higher rear drive than the VVC (3.397 compared with 4.2 to 1), so acceleration could be slightly worse, compared with natural born VVC's. How it will be compared with an Mpi I don't know.

On a personal note I'd spend my money on other ways to make the car better, but it is of course your own decision. The VVC is rattlier and more fragile, and it sounds like a lot of work. I like the Mpi!

Regards, Kes.
Kes

Kes, you beat me to it ;o) Not often Will gets something wrong...

Sander, converting a 1.8i to VVC has certainly been done, and done a number of times, both in MGs and in Lotus Elises.

How easy it is to convert your car depends on the age of your car, and the age of the cylinder head you've bought. For example, if your MGF is a pre-2001 car, and you've bought a cylinder head from a post-2001 MG, then you will run into some problems in that some of the sensor specifications are different.

That said, it is still possible.

You will need a VVC engine wiring loom, a MEMS 2J ECU (or MEMS3 programmed to run a VVC, or an Emerald M3D ECU). You will need a new cam cover to suit the VVC cylinder head.

If you are attaching your VVC head to an early 1.8i engine, bear in mind that the bottom end specification of these early engines are inferior to the VVC and later 1.8 engines (bearing specs commonalised to VVC specifications post 2001 IIRC). You may not have problems, but bear in mind that your engine will loose reliability if run significantly above the original 1.8i's rev limit of 6750 (VVC rev limit 7250).

Using the same gearbox and final drive poses no problem whatsoever - just that you'll loose some in-gear acceleration due to the higher final drive ratio of the 1.8 - but then you'll gain on fuel economy :o)

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

>Not often Will gets something wrong...

LOL, just as faliable as the rest - I just hide it well ;-)

Will Munns

You will need..

ECU
Loom
Inlet plenum and TB
Twin coil setup and leads
Cambelt covers both back and front for the front cambelt
A new cambelt and manual tensioner

You do not need a new cam cover... just make sure you use a post '98 cam cover gasket.

I have seen 179BHP from the stock ECU with ported head, better exhaust cam, retimed VVC mechs, 52mm TB and 4-2-1.

Dave

Dave Andrews

That's allot of replies and good food for the brain ;) Thanks !

>>>I am sure the F VVC engine has the MAP sensor on the manifold itself, while the sensor at the MPi version of the F, is located at the ECU/MEMS. How is this arranged on the TF's ?<<<

The TF135 uses a MAPT (MAP + temperature in one sensor) I think TF VVC uses the same sensors ?

>>>Why would you go for the Rover ECU, while there is an Emerald able to operate the VVC mechanisme ?<<<

Because Bruno has a spare MEMS2 which I'm sure he wants to lend me for testing ;)

>>>On a personal note I'd spend my money on other ways to make the car better, but it is of course your own decision. The VVC is rattlier and more fragile, and it sounds like a lot of work. I like the Mpi!<<<

I like the MPi also but we've seen 160BHP from VVC's with just bolt-on parts. Getting 160bhp form a MPi will require more expensive tuning and losing bottom-end torque I guess ?

>>>How easy it is to convert your car depends on the age of your car, and the age of the cylinder head you've bought. For example, if your MGF is a pre-2001 car, and you've bought a cylinder head from a post-2001 MG, then you will run into some problems in that some of the sensor specifications are different.<<<

I've obtained an Elise 111S cilinder head with the added grooves arround the exhaust valves (and smaller grooves arround the inlet valves ?) I believe this is the 160bhp (post 2001?) cilinderhead. I didn't know the sensors were different. I thought only the inletmanifold sensors and the second lambda would be the difference ? You can see pictures of the head here:
http://dennis.core-lan.nl/mgf/album56/IMG_4308
and here:
http://dennis.core-lan.nl/mgf/album56/IMG_4310

>>>If you are attaching your VVC head to an early 1.8i engine, bear in mind that the bottom end specification of these early engines are inferior to the VVC and later 1.8 engines (bearing specs commonalised to VVC specifications post 2001 IIRC). You may not have problems, but bear in mind that your engine will loose reliability if run significantly above the original 1.8i's rev limit of 6750 (VVC rev limit 7250).<<<

I didn't know that ! That's kind of disappointing. Will the bottom end mainly suffer from high revs and not the higher power ? If I blowup the bottom end is it possible to upgrade the bearings to VVC spec or is the casting different so I would be better of sourcing a VVC bottom end ?

>>>You do not need a new cam cover... just make sure you use a post '98 cam cover gasket.

I have seen 179BHP from the stock ECU with ported head, better exhaust cam, retimed VVC mechs, 52mm TB and 4-2-1.<<<

Thanks for that, I'll surely think of you when the head needs porting :) What is involved with retiming the VVC mechs ? Verniers on both sides of the exhaust cam ?

Sander

Sander, the 1.8 bottom can readily be re-built to later spec with up-rated bearings etc. The comment was meant more as a heads-up, so if something untoward happens, you'll know why! :o)

Dave Livingstone's VVC (with DVA ported head) is currently making 175bhp with a standard manifold. He's replaced this with a Powerspeed 4-2-1 (as have I on my 1.8i), and we're planning to head over to Emerald some time in the new year to see how this combination works. We'll keep everyone posted as to progress.

As regard to VVC valve timing - I'd better let Dave answer that question, but as I recall, he adjusts timing using off-set dowels on the VVC...

Anyone tried a VVC with DTA throttle bodies yet?
Rob Bell

>>>If you are attaching your VVC head to an early 1.8i engine, bear in mind that the bottom end specification of these early engines are inferior to the VVC and later 1.8 engines (bearing specs commonalised to VVC specifications post 2001 IIRC). You may not have problems, but bear in mind that your engine will loose reliability if run significantly above the original 1.8i's rev limit of 6750 (VVC rev limit 7250).<<<
Any idea if this is also true for early Elises ? I just want to know 'cause PTP is/was selling the RT Sport 165 kit which revs up to 7300rpm and this is developed for the Elises.

>>>
>>>Why would you go for the Rover ECU, while there is an Emerald able to operate the VVC mechanisme ?<<<

Because Bruno has a spare MEMS2 which I'm sure he wants to lend me for testing ;) <<<
So I warn you if a VVC MEMS shows up at ebay or somewhere else.
Erik

>>>So I warn you if a VVC MEMS shows up at ebay or somewhere else.

You can also warn me for:
- VVC inlet manifold
- VVC coilpack
- VVC engine loom (think this will be the difficult part)

Right now I believe it's best to go for MEMS2 compatible parts since the car-engine connection will be the easiest.

;)


Sander

>>Any idea if this is also true for early Elises ? I just want to know 'cause PTP is/was selling the RT Sport 165 kit which revs up to 7300rpm and this is developed for the Elises.<<

Yes, it is true of Elises. I suspect that PTP probably sell the engine as a complete package don't they?
Rob Bell

The VVC mechs are indeed retimed using offset dowels. In my experience both of the VVC mechs and the exhaust cam run retarded by around 6-8 degrees; the use of an offset dowel in the front VVC mech and the front of the exhaust cam corrects the front VVC mech, the exhaust cam and the rear mech via the exhaust cam.

A siz degree dowel in each normally gets all three cams within a degree or two.

The lift at TDC should be a noiminal 0 thou on the VVC cams, with lift starting *immediately* after TDC (that is with the VVC mechs fully retarded), Lift at TDC on the exhaust cam should be around 35 thou.

Dave
Dave Andrews

Just a question,
not specifically on topic, but cyl.head related.

I checked my EPC and noticed for the MPI with my VIN n° (SARRDWBGMXD508502) the following possible inlet camshaft options:

partn° LCG105990 MPI camshaft inlet assy high performance S/N 196827 - 694354

partn° LGC107550 MPI camshaft inlet assy
S/N 694354 onwards.

1. why canīt rover dedicate 1 camshaft for my VINn°?

2. Surely mpi heads have not been available with high performance camshafts? My S/N falls in the high "performance" S/N range, but I have a regular mpi (for now ;-) )

I believe the MGR EPC still has some glitches...*LOL*

can someone shed a light on this.

As for the VVC head. Is the VVC mech mechanically or electrically controlled ?
If mechanically, the MPI loom can't be that different from a VVC loom. Only the MAP sensor wire would be additional to Sanderīs MPI loom. Wiring to the coil pack is the same not? Or did the vvc have distributorless ign. from the start?

cheers,
david
David Peters

David,

The VVC mechanism is hydraulically *actuated*, but electronically controlled. It has the following additonal items which are served by the loom.

Cam phase/VVC extension sensor
Oil temperature sensor on actuator
VVC actuator solenoid - extend
VVC actuator solenoid - retract
MAP sensor.

In addition it has a two plug strategy for the ECU on EU2 variants.

The VVC of necessity has ditributorless ignition since there is nowhere to mount the distributor cap, EU2 variants have a block mounted twin coil setup, EU3 variants have two wasted spark type plug top coils.

Dave
Dave Andrews

>>1. why canīt rover dedicate 1 camshaft for my VINn°?
2. Surely mpi heads have not been available with high performance camshafts? My S/N falls in the high "performance" S/N range, but I have a regular mpi (for now ;-) )<<

Ah, the dear old EPC. Fantastically useful for many things, but in the area of obtaining the right cam... er... hopeless, as you've found out. The part numbers and what, exactly, they refer too is as about as clear as a puddle of muddy water. :o(

I suspect that the "High Performance" cams may be the ones specified for the TF135. However, the part number stamped on these cams do not match any in the EPC. Go figure - I'm still scratching my head over this one.
Rob Bell

I've just examined the VVC head a little further and I noticed the exhaust cam uses a pully which seem to be made heavier on puspose. It has a rubber ring in it which is attached to a metal weight. This weight is given some free play by the rubber sleeve.

What's the purpose of this construction ? ballancing of some sort ?
Sander

long shot in the dark: could it be used for injector timing ?
Erik

I can't see how. And why would this part be different for the VVC ?
Sander

If I would be you would stick to the MPI rather than going for a VVC conversion. I have owned both and can state that the VVC mechanism is very complicated and very often troubled. Difference among both MPI and VVC is really small and you can not really notice most of the time. There many mods which will improve your MPI beyond the VVC possibilities and your car will be more reliable -may reliability could be mentioned in connection to a MGF-.
Derek Foster

I've got everything you need to convert an early MPI to a VVC if anyones interested.
Lord Sward

The VVC exhaust pulley contains a torsional damper to damp the load fluctuations caused by the VVC mechs. Normally a camshafts spring harmonics are balanced along the shaft since as one spring/valve opens, it's opposite nnumbr in the engine cycle is closing, which helps to balance the cyclical stresses. With the VVC, only the front cam is driven by the front belt so there are no balancing forces prodived by the rearmost two cylinders, these are driven by the exhaust cam and the opposing forces are absorbed by the exhaust cam which will now have unbalanced cyclical forces. All together a recipe for vibration and torsional stress.

Dave
Dave Andrews

@Derek,
Improving the MPi's output power usually means sacrificing torque (hotter cams) since I do allot of "cruising" with it I like to keep (at least some of)my low-rev-torque. The thing I like about the VVC is you get more power but you can (more or less) keep the torque. On top of that all the VVC mechanics came with the head I've bought and are just 5000mls old so why throw them away and spend additional money on a blanking kit and camshafts ? I'm currently after 180bhp on a plenum so keeping the VVC will be cheapest I think. If the bottom-end fails one day I might be tempted to upgrade the bottom-end and fit solid cams with DTH TB's elaborating more power :) It will all depent on the outcome of this tuning adventure :)

@Lord Sward,
I might be interested in a few things if you are willing to sell items as seperate. Please send me an email an I'll reply with the thing's I'm still looking for.

@Dave,
Thanks for that, why does everyting sound so simple >afer< you've told it ;)

Sander

This thread was discussed between 20/12/2005 and 29/12/2005

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