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snoopy64
Member
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Posted: Sunday October 28th, 2007 07:44 pm |
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Hi all, new to the game, well after a 25 year break!! Got a great very late Cooper Sport, bit dissappointed with the performance though, have had it a few months now, it's had a good service, done 30k.
Anyone recommend an engine mod?
I understand the 90hp JCW is still available, is that official, is it worth the cash? Have heard other less drastics tweeks are possible.
Would appreciate the voices of experience. Probably an old chestnut!!
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taffy1967
Member
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Posted: Monday October 29th, 2007 12:26 am |
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I doubt you could get the conversion done by John Cooper Garages, because they've now completely finished with classic Minis.
I believe this company will do the work, since it's run by an ex-employee of JCG: -
http://www.classicminis-online.co.uk/
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oz
Moderator
| Joined: | Wednesday January 31st, 2007 |
| Location: | Livingston |
| Posts: | 67 |
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Posted: Wednesday October 31st, 2007 12:49 am |
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I've not done any serious mods to the engine on my MPI.
I've fitted a K&N air filter, done some mods to the filter housing and removed the L shaped restricter bracket on the side of the throttle body.
Contemplating fitting a larger throttle body but not sure cos I've heard that you need a remap of the ECU.
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snoopy64
Member
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Posted: Wednesday October 31st, 2007 05:58 pm |
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| Thanks for that. Am very tempeted by the 90bhp conversion, there are a couple of original JC branded kits left. But I have heard that they are not good for the engine, can this be right as the A series unit is so de-tuned??
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Wednesday October 31st, 2007 08:49 pm |
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oz wrote: I've not done any serious mods to the engine on my MPI.
I've fitted a K&N air filter, done some mods to the filter housing and removed the L shaped restricter bracket on the side of the throttle body.
Removing the throttle stop is a bad idea, as it's possible to now take the throttle disk past 90deg, effectively closing it again. You can refit the bracket, then grind it down until the throttle reaches 90deg.
I cant really see how the JCG kit can be bad for the engine, mines been on there since 2004 and had been in daily use until this year, no problems with the engine so far.
An RC-40 exhaust system would be the first start for tuning, the standard one is too restrictive. No need to remove the cat as modern cats are pretty efficient, removing it would only give you maybe 1bhp at the very top end of the power band.
The main reason the MPi's "feel" sluggish is their high final drive, it gives you a quieter drive, higher top speed and better economy, but at the expence of acceleration.
Some will tell you that there are better value tuning kits out there, but the JCG one has actually been developed, it makes little difference to the fuel economy for example. Many of the other cheaper kits are pretty much a bunch of parts thrown in a box based on someones 'opinion' of what they might do for the performance.
The larger 52mm throttle bodies do apparently make a difference, and there is no need to remap the ECU (actually you cant really remap it, its self adjusting,up to a point) If you have the original Plastic throttle body, they tend to crack and warp anyway.
I think the first step you could make is changing the exhaust, I changed mine to an RC40 twin box from the cat back before i had the JC kit fitted and it did make it more responsive.
Also decent quality petrol makes a big difference too, mine runs on Supermarket stuff, but goes like stink on Shell and BP petrol, the V-Power/ultimate fuels are slightly better still.
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snoopy64
Member
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Posted: Wednesday October 31st, 2007 10:16 pm |
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| Thanks Hb that's a comfort to here. how many miles has your JC conversion done? I'm swinging back towards it now.
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sparkymini
Member
| Joined: | Monday October 29th, 2007 |
| Location: | |
| Posts: | 5 |
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Posted: Thursday November 1st, 2007 11:58 am |
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i've got
stage 3 head
Burlen 52m throttle
Worked airbox with K&N
3.1 final drive (which makes it drive like a proper mini)
SW5i cam - the best for MPI
Lightened and Balanced Flywheel
Straight cut drops
uprated fuel pressure valve
Duplex Alloy Vernier Pully
RC50 with CAT bypass
Which makes for a nippy and still extremely reliable mini, anything more than that you'll be looking at having to buy an Emerald ECU
also being a lady, and having a sensible head, its also got KAD brakes, minifins, and a fully adjustable mostly KAD suspension set up, oo and the subframes have been seamwelded to give the extra stability, with solid mounts
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Friday November 2nd, 2007 07:21 pm |
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| she's on about 70k now, i think she had about 40 on the clock when i had the kit fitted. I'd have to check my records to be totally certain though.
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nige_w
Member
| Joined: | Thursday September 27th, 2007 |
| Location: | |
| Posts: | 11 |
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Posted: Wednesday December 5th, 2007 02:30 pm |
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Hi, had this done to my previous Mini and wasn't entirely happy with it. Apart from changes to rockers, JanSpeed exhaust etc, also included a chip to run the fuel mix richer which gave me a few problems. Eventually had the chip removed.
At its best I don't think I got near 90hp. Also spent a lot of time having it serviced due to rich running. May have just been unlucky.
Gear boxes on these later ones had quite long gearing for motorway driving. Changing the gearing would make some difference I expect without even touching the engine.
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Wednesday December 5th, 2007 05:40 pm |
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| The JC conversion never came with a 'chip' just an uprated fuel pressure regulator, a very simple device.
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Graham Bichard
Member
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Posted: Thursday December 6th, 2007 09:57 am |
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Good question about mods this - it's the sort of thing I'll get around to eventually.
I fitted the 57i K&N kit to my mini, and promptly took it off again! Too noisy (nice for short distances but I try and use mine whenever possible even if it is a long/motorway trip), I replaced it with a K&N element in the standard housing. I seem to remember the car feeling a bit nippier with the 57i fitted though.
As for exhausts, I thought about getting a LCB manifold, but to be honest I've heard resonable things about fitting a 'magic pipe' to the MPi - with the extent of tuning available on the MPi, is it worth the extra expense of the manifold, any thoughts?
One thing I won't be doing is changing the gearing (because of the possible motorway journeys). But I am in two minds about fitting increased ratio roller rockers. I have heard that this can have a detrimental effect on MPi's regarding emissions. Again has anyone done this, or experienced the effects? I don't really want to change the cam (although when I get around to rebuilding a gearbox / engine out, I might change my mind! Usually do!)
I will eventually get a more efficient head fitted (may even have a go at porting one myself) and also the 52mm throttle body, but all these mods would need a cumulative effect for me - I'll only be able to afford (time & money) one stage at a time.
So yes I'm interested in the thread, and of peoples experiences of modding!
Last edited on Thursday December 6th, 2007 09:58 am by Graham Bichard |
hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Thursday December 6th, 2007 05:54 pm |
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mine has high ratio rockers, part of the JC kit. It's always passed MOT's fine, fitting high ratio rockers has the same effect as fitting a slightly hotter cam shaft.
With regards to gearing you could always fit a 5 speed box with a lower diff ratio, then you get better acceleration, plus you still keep the top speed and cruising ability.
Reducing the over all gearing, does improve 0-60 times, but it also reduces your top speed.
Induction kits do generally make cars 'feel' more nippy, but it's more of a psycological effect due to the increased roar when you put your foot down i think. So they always sound like they make more of a difference than they really do.
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Graham Bichard
Member
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Posted: Friday December 7th, 2007 06:29 am |
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hb, I totally agree with your comments about the induction roar - how much of the effect is 'in the head'?
You've got my thinking spot on about the high ratio roller rockers, the effects of a hotter camshaft but without changing the cam itself, thereby giving me a bit more performance. But, my next question(s) is, what ratio is your new rocker shaft? And would it work effectively without changing the head itself (without affecting the emissions)? Or would the rockers only give an increase when used in conjunction with a new, ported head? In fact how would an MPi react to having just high ratio rockers fitter? Can it adjust itself enough? I'm guessing so as it seems to be part of the kits (along with head/manifold etc) you can get. (Weren't things easier with carbs & needles and stuff!!!)
My gearbox needs a rebuild ('there plenty of life left in it yet!' - hopefully!) and I would love to fit a five speed gearbox, the biggest limiting factor being the cost. Also in my limited investigation, it seems almost impossible to get a road going (i.e. NOT straight cut) 5 speeder these days. Unless anyone knows different.
Anyway, I'll be keeping an eye on this thread to see if anyone else has done the piecemeal approach to modding (while doing the important stuff, like wheel bearings, on my car first!).
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Friday December 7th, 2007 03:10 pm |
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Minispares sell 5 speed all helical boxes, and gear kits too i think. I believe they're special order though. Jack knight who originally made the 5 Speed boxes for JCG are still going, whilst they may not 'list' a helical all syncro box, i'm sure they could still supply one.
Thing is decent roller high ratio rockers are getting close to £300, so i doubt they'll make a worthwhile increase on their own compared to the price. Although the good thing about rockers is, you can fit them, if it makes the car run rough or too lean, you can always swap them back in an hour or less. I doubt emisions would be a problem with just rockers as if anything the car would run too lean rather than too rich.
I think the vast majority of the extra performance comes from the stage 3 head, but you will need the uprated fuel pressure regulator, this has the same effect as changing the needle/jet in an SU. Do a google search for common rail electronic fuel injection systems, it's not so much of a black art really.
I cant remember what ratio my rockers were, 1.5's i think.
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mpiman
Member
| Joined: | Monday January 23rd, 2006 |
| Location: | |
| Posts: | 5 |
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Posted: Friday December 7th, 2007 09:29 pm |
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I believe Mike Raven owner of Classic Minis may well have just 1 original new JCG 90 BHP kit left, worth a phone call 01903 859430. I don't think there is much wrong with the JCG kit although 90BHP may be a little optimistic.
My own mpi has gone through a number of stages of build over the last few years and is currently a 1380 with Stage 3 head, roller rockers, SW5i cam, race valves & springs, 52mm throttle body, lightened flywheel, OAP Miglia crank, belt drive, modified inlet manifold, adj fuel presure regulator, 3.44 final drive, turbo clutch, lightened & balanced rods, maniflow manifold and exhaust etc etc etc etc.
I still run the standard ECU, the car performs well with very good acceleration and although it gets there quickly it does runs out of revs at about 106 mph, it does however have good fuel economy of 40 plus, always passes the MOT, has the cat left on at all times and does not overheat.
It did have the K& N mpi kit fitted which I must admit did look good but on the rolling road at Slarks it was actually loosing it BHP against the standard box which I have now refitted athough it is modified as the JCG one is. The problem was the K& N was weakening the mixture and the car would run lean.
email me if you need any more info
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Saturday December 8th, 2007 09:43 pm |
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I think it's probably 90bhp AT THE FLYWHEEL on a properly assembled engine, if tested on a proper engine dyno and not a rolling road.
I think the trouble with many of the figures you see in the mags is they're all done on rolling roads, so they only tell the performance AT THE WHEELS, it's then pretty much up to the operators opinion or the opinion of the RR makers what the transmisive loss will be. Then you have the variation in calibration of the RR and then there are other factors such as condition of the engine, type of tyres used on the test car, condition of gearbox, condition of the wheel bearings, quality of air and fuel. There are so many variables on a rolling road, where they're eliminated only by best guess.
I suspect the 90bhp figure came from a true engine dyno, thats a hand built engine with perfect timing hooked up to a dyno without a car, with thermostatically controlled air supply, high quality fuel, and the gearbox, disengaged with the flywheel connected directly to a brake.
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mpiman
Member
| Joined: | Monday January 23rd, 2006 |
| Location: | |
| Posts: | 5 |
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Posted: Sunday December 9th, 2007 01:47 pm |
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I agree with the views expressed regarding RRs, the following are a series of results from different RRs for the JCG 90BHP conversion, all are at the flywheel.
63.10, 67.50, 70, 70, 81, 81.19, 81.65, 84.20, 84.50
quite arange of figures
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Sunday December 9th, 2007 05:30 pm |
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Exactly, it may be the 63bhp car was defective, but then it could even be caused by something as simple as under inflated tyres.
I think doing a rolling road day with your mates is a good way of comparing each others cars relative to each other, ie. point at your mate and say 'ner mines better than yours', but i dont know that you can say the actual output figures mean very much.
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DaveShreeve
Administrator
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Posted: Sunday December 9th, 2007 09:44 pm |
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| I'd generally agree with hb, however, rolling roads are also very useful for checking what you're doing; presuming the operator doesn't mod the road, and even then they usually have a good idea what correction factors to apply between old and new. You still have to make allowance for atmospheric conditions but if you've got a starting point before you start modding you can at least see you're personal gains.
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Graham Bichard
Member
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Posted: Monday December 10th, 2007 08:16 am |
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| I had a 998cc Mayfair that had 28 Bhp at the wheels on a rolling road, once...............
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