Discussion
I'm trying to increase my knowledge of my car with a view to eventually improving it.
To that end does anyone know the timing of the standard MPi cam?
Cooperman, you've told me in the past you've rebuilt MPi's using the standard cam, can you help?
Has anyone any experience using any different cam? I'm aware the standard fueling with the ECU is a limiting factor, so are the advertised Injection cams just a ploy to take money off of us? If the standard cam is as 'mild' as I've read, and fueling is the limiting factor surely there's no point in using a hotter cam?
I do know you can get the uprated fuel regulator, also using higher ratio rockers, but don't these lead to problems with emissions?
Just thought I'd ask.....
To that end does anyone know the timing of the standard MPi cam?
Cooperman, you've told me in the past you've rebuilt MPi's using the standard cam, can you help?
Has anyone any experience using any different cam? I'm aware the standard fueling with the ECU is a limiting factor, so are the advertised Injection cams just a ploy to take money off of us? If the standard cam is as 'mild' as I've read, and fueling is the limiting factor surely there's no point in using a hotter cam?
I do know you can get the uprated fuel regulator, also using higher ratio rockers, but don't these lead to problems with emissions?
Just thought I'd ask.....
Virtually all BMC/ARG/Rover standard cams time in at 110 deg ATDC (inlet), whereas the Kent range time in at 106 deg ATDC.
I usually time cams in about 2 deg advanced from that (i.e. 108 deg and 104 deg, respectively). Remember, the timing chain stretches most during the initial 1000 miles and this effectively retards the cam timing slightly. By setting the 2 deg extra advance, you are optimising the cam timing during the greatest part of the chain life.
Of course, others may think differently!
I usually time cams in about 2 deg advanced from that (i.e. 108 deg and 104 deg, respectively). Remember, the timing chain stretches most during the initial 1000 miles and this effectively retards the cam timing slightly. By setting the 2 deg extra advance, you are optimising the cam timing during the greatest part of the chain life.
Of course, others may think differently!
Edited by Cooperman on Monday 3rd March 16:53
Cheers cooperman, this ties in with what Vizard says in the book (as you know my knowledge is all theoretical 
)and I don't always believe what I read (or at least question it!).
But he does talk about timing cams so they are 2-4 degrees advanced in normal operation, as it tends to give more power. Why wouldn't Austin/Morris/BL/Rover et al cotton on to this and adjust their recommended cam timing to take advantage of this? (See, I said I question what I read!).
I've also read that the MPi cam is VERY mild - do you (or anyone) know the BTDC/ATDC degrees for inlet/exhaust, and what is the standard lift of the MPi cam?
Oh, and I think I've got a cylinder head Peter - I'll e-mail you more questions about this later (More questions I'm afraid!).
)and I don't always believe what I read (or at least question it!).But he does talk about timing cams so they are 2-4 degrees advanced in normal operation, as it tends to give more power. Why wouldn't Austin/Morris/BL/Rover et al cotton on to this and adjust their recommended cam timing to take advantage of this? (See, I said I question what I read!).
I've also read that the MPi cam is VERY mild - do you (or anyone) know the BTDC/ATDC degrees for inlet/exhaust, and what is the standard lift of the MPi cam?
Oh, and I think I've got a cylinder head Peter - I'll e-mail you more questions about this later (More questions I'm afraid!).
The actual cam profile/timing figures for that cam do seem to be a secret. I have nothing which tells me what they are. I guess the only way to be sure would be to produce a cam diagram by rotating the cam between centres with a DTI and a protractor and measuring the lift every 10 degrees for one complete revolution after determining the zero-datum.
The problem with the MPI can be the emissions check for the MoT. I recently had to do a complete re-build of a John Cooper 'S-Works' which, at 80,000 miles, would not pass. The cam was replaced by a new standard one and the offset 1.5:1 rockers replaced by standard ones. With all new pistons, out to 1330 cc, and a re-built head/valves/guides, slightly increased comp ratio, etc, it passed easily. I was somewhat disappointed at the quality of the gas-flowing of the John Cooper modified head though. They are very expensive, but no attempt had been made to improve the exhaust porting at all. I did some more work on the head and although it went back to a standard new cam and rocker shaft, the owner said that it went better than it had ever done from new. Maybe the key to getting better power from the MPI is to improve the breathing and increase the capacity and comp ratio.
The problem with the MPI can be the emissions check for the MoT. I recently had to do a complete re-build of a John Cooper 'S-Works' which, at 80,000 miles, would not pass. The cam was replaced by a new standard one and the offset 1.5:1 rockers replaced by standard ones. With all new pistons, out to 1330 cc, and a re-built head/valves/guides, slightly increased comp ratio, etc, it passed easily. I was somewhat disappointed at the quality of the gas-flowing of the John Cooper modified head though. They are very expensive, but no attempt had been made to improve the exhaust porting at all. I did some more work on the head and although it went back to a standard new cam and rocker shaft, the owner said that it went better than it had ever done from new. Maybe the key to getting better power from the MPI is to improve the breathing and increase the capacity and comp ratio.
Thats kind of what I'm (ultimately)trying to produce, cooperman, the engine you've rebuilt.
We've spoken before about the high lift rockers (and don't now really want to use them) but I'm interested in what lift the standard cam produces (out of curiosity mostly!). I can't see me going to the extremes of measuring a cam, but am interested in knowing if something like the SW5i cam (which seems to be the popular injection choice) gives a worthwhile improvement without falling foul of the emissions - I suspect not!!! Gains/cost etc. I'm a LONG way off sorting out a bottom end, but thinking about all this stuff keeps the brain ticking over!
As for the standard of the JCG cylinder head, well, we all know mine will be better
We've spoken before about the high lift rockers (and don't now really want to use them) but I'm interested in what lift the standard cam produces (out of curiosity mostly!). I can't see me going to the extremes of measuring a cam, but am interested in knowing if something like the SW5i cam (which seems to be the popular injection choice) gives a worthwhile improvement without falling foul of the emissions - I suspect not!!! Gains/cost etc. I'm a LONG way off sorting out a bottom end, but thinking about all this stuff keeps the brain ticking over!
As for the standard of the JCG cylinder head, well, we all know mine will be better
It's a personal opinion, but after all my years with Minis of all types I am firmly of the belief that the best way to improve the road performance of any Mini is to ensure that everthing except the engine is set-up first. In fact, my priority order for doing thing to improve performance is as follows:
1. Ensure that the rear suspension is correctly set to zero to -1 degree neg camber with a toe-in of 1/16" to 1/8" and with the rear wheels in line with the fronts. It's surprising how many Minis go along 'crabwise' (if anyone wants, I'll post the easy way for doing all this using a piece of timber and a square board).
2. Set the front suspension to a small amount of neg camber using the offset lower arm bushes. You can use neg camber bottom arms to give -1.5 degrees, but I am thinking of the lowest cost way. The tracking should be 'straight ahead'. Adjustable tie bars are useful for fine setting of castor angle.
3. Make sure the ride height is standard. If a Mini is lowered, which is fine for the race track, there can be insufficient suspension travel for normal road bumps and a car won't steer when the suspension is hard down on the bump stops.
4 Change the dampers for adjustable ones like GAZ or SPAX. I've never really liked KONI for the road as they are soft on bump and stiffer on rebound. Again, fine for racing, but for the road you really need the equal double bump/rebound stiffness which GAZ and SPAX give.
5. Check out the braking system and fit improved pads such as Mintex 1155 or better. I have little experience of EBC, but I'm told their 'Green stuff' is a good alternative to Mintex. Don't worry too much about the rear brakes as they do little actual work in slowing from higher speeds. Make sure the discs are good too. The rear disc brake conversions for Minis are a complete waste of money, but good for those selling them!
6. Think about the uses to which the car is needed and select a diff ratio for that use. If a lot of motorway driving is planned, than maybe a 2.9 or 3.1 is best, but for twisty lanes and minor A-roads, a 3.44 could be much better.
6. Now the car will go around corners and allow later braking, it will be time to do some engine work.
The old adage 'don't make it faster until it corners and stops as well as it possibly can' always holds true.
I hope all this helps.
Peter
1. Ensure that the rear suspension is correctly set to zero to -1 degree neg camber with a toe-in of 1/16" to 1/8" and with the rear wheels in line with the fronts. It's surprising how many Minis go along 'crabwise' (if anyone wants, I'll post the easy way for doing all this using a piece of timber and a square board).
2. Set the front suspension to a small amount of neg camber using the offset lower arm bushes. You can use neg camber bottom arms to give -1.5 degrees, but I am thinking of the lowest cost way. The tracking should be 'straight ahead'. Adjustable tie bars are useful for fine setting of castor angle.
3. Make sure the ride height is standard. If a Mini is lowered, which is fine for the race track, there can be insufficient suspension travel for normal road bumps and a car won't steer when the suspension is hard down on the bump stops.
4 Change the dampers for adjustable ones like GAZ or SPAX. I've never really liked KONI for the road as they are soft on bump and stiffer on rebound. Again, fine for racing, but for the road you really need the equal double bump/rebound stiffness which GAZ and SPAX give.
5. Check out the braking system and fit improved pads such as Mintex 1155 or better. I have little experience of EBC, but I'm told their 'Green stuff' is a good alternative to Mintex. Don't worry too much about the rear brakes as they do little actual work in slowing from higher speeds. Make sure the discs are good too. The rear disc brake conversions for Minis are a complete waste of money, but good for those selling them!
6. Think about the uses to which the car is needed and select a diff ratio for that use. If a lot of motorway driving is planned, than maybe a 2.9 or 3.1 is best, but for twisty lanes and minor A-roads, a 3.44 could be much better.
6. Now the car will go around corners and allow later braking, it will be time to do some engine work.
The old adage 'don't make it faster until it corners and stops as well as it possibly can' always holds true.
I hope all this helps.
Peter
cooperman, I'm at stage '3' (completed) with stage '5' completed too .
And yes, do post how to do the geometry with string and a board - I'm going to be tackling this over the Easter break I hope!
Regarding the ride height, I'd be interested what you set your cars at. I started a topic on the Mini Cooper Register website discussing this very topic - I need to reset/check my car after replacing bits and pieces.
(And I will eventually get the geometry figures to you as we discussed - won't be next week tho, I'm going skiing! Even better - its thru work!!!)
. And yes, do post how to do the geometry with string and a board - I'm going to be tackling this over the Easter break I hope!
Regarding the ride height, I'd be interested what you set your cars at. I started a topic on the Mini Cooper Register website discussing this very topic - I need to reset/check my car after replacing bits and pieces.
(And I will eventually get the geometry figures to you as we discussed
- won't be next week tho, I'm going skiing! Even better - its thru work!!!)It might be a bit long to post on here in its entirety, but I'll ask MiniMan (James) if he will host it on his website for me as he's done before with a suspension geometry bit I wrote a while back.
In fact I did the rear suspension job with my Grandson (Mayfair Kid on here) last weekend and it took most of a morning. However, we had done the geometry calculations the evening before, so it was just measuring, filing, then a bit of welding.
In fact I did the rear suspension job with my Grandson (Mayfair Kid on here) last weekend and it took most of a morning. However, we had done the geometry calculations the evening before, so it was just measuring, filing, then a bit of welding.
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