Discussion
I own a Cooper 500 Sport MPI, and am looking to increase performance, i have a budget of around one and a half grand (Can be increased if needed) and am just looking for some improvement in acceleration (just to eat those silly little boys in their Nova's). But after reading the article in 'Keeping Your Mini Alive 4' i've been somewhat disheartened, they managed to make it sound like it was more trouble than it was worth.
Any advice welcomed....
Any advice welcomed....
From what I’ve been told the mpi system can’t be played with so a new mapable injection is needed. That's why older coopers often go back to carbs, you could get a head etc but to get the most out of it you’d need to spend big money setting up the fuelling. I looked into tuning my 1996 equinox 1.3 spi but ended up selling and getting an older car.
It is possible to tune the injection models without resorting to a new ECU, but you are limited. All the usual modifications work, better exhaust, inlet, head, cam etc, the limitation is with the Rover ECU. It does have an 02 or lamda sensor, so it can increase the fuel a bit for a small increase in air-flow. However, you can't reprogram or "chip" it in the traditional sense. This is the bain of MGF/TF, Elise and Caterham tuners too. If you need different ignition or lots more fuel you can't change the maps. There are ways of "cheating" like using a rising rate fuel pressure regulator like those made by FSE (power-boost valves I think they are called), or by using Superchip's ICON intercepter ECU. This device is wired between the Rover ECU and the engine sensors, and fudges the data from the sensors into the ECU, effectively fooling the ECU into thinking the engine is somewhere else in its operating map. This works fine for outputs upto about 90hp @ flywheel, and most of the Si kits use one, other or both the above.
With a high output motor (>90hp) you now run out of injector time before making peak power, so you think move up to the next size injector. Now the standard injector times at idle flow too much fuel for a nice smooth idle..... So you replace the ECU with an aftermarked one. Now you can reduce the injector time low enough for idle speed, but the atomisation at very low times is poor so you still have a poor idle. Rover recongnised this and fitted something called the idle air control valve or stepper motor valve on the standard injection system. It's all good fun isn't it ?? Mike Barratt in Lincoln has been working on a system for high output minis in conjunction with MiniSpares centre and Keith Calver of Mini Magazine, it's in the May issue of the mag and is on the MiniSpares web site.
With a high output motor (>90hp) you now run out of injector time before making peak power, so you think move up to the next size injector. Now the standard injector times at idle flow too much fuel for a nice smooth idle..... So you replace the ECU with an aftermarked one. Now you can reduce the injector time low enough for idle speed, but the atomisation at very low times is poor so you still have a poor idle. Rover recongnised this and fitted something called the idle air control valve or stepper motor valve on the standard injection system. It's all good fun isn't it ?? Mike Barratt in Lincoln has been working on a system for high output minis in conjunction with MiniSpares centre and Keith Calver of Mini Magazine, it's in the May issue of the mag and is on the MiniSpares web site.
Mini's can be a pain to put management on due to the siamise inlet port configuration. Lots of cylinder robbing takes place and Rover performed some clever trickery as far as injector timing and pulse width are concerned to get over the problems. It can, and has been done however. Programmable, after market ECU's are the best way to go, (much preferred to ICON unit in my opinion) and provided it's all set up on a reputatble rolling road with someone who knows what they're doing you shouldn't have any problems. A very good ECU can be had for no more than £600. Factor in a £200 rolling road mapping session and you're still well within your budget when you add a cam and head to the list.
However, if it's purely accel improvement your after I would investigate lightening the flywheel and raising the diff ratio. Accel and engine response will improve at the expense of higher cruising revs.
However, if it's purely accel improvement your after I would investigate lightening the flywheel and raising the diff ratio. Accel and engine response will improve at the expense of higher cruising revs.
Well thanks you for the advice. Since then i have spent most of that money and have a few bits to show for it. The car is in pieces in the garage waiting to have them all installed, and will probably be out of action for another month (unfortunately i dont have enough spare time to work on her, allways the way).
I ended up taking some of your advice as well as what other people told me. i bought a new exhaust system, air filter, lightened the flywheel, polished the inlet manifold, got an LCB exhaust manifold, a new final drive, a "stage 3" head from MED, and some roller rockers, i think thats about it. this should take me up to 90 at the flywheel with any luck.
You said something about a decent ecu being available for around 600, i don't suppose you know which ecu and where it is available from do you?
I ended up taking some of your advice as well as what other people told me. i bought a new exhaust system, air filter, lightened the flywheel, polished the inlet manifold, got an LCB exhaust manifold, a new final drive, a "stage 3" head from MED, and some roller rockers, i think thats about it. this should take me up to 90 at the flywheel with any luck.
You said something about a decent ecu being available for around 600, i don't suppose you know which ecu and where it is available from do you?
Now I'm not an expert on injection cars, but I did hear that if you remove the temperature sensor which sends the temp to the ECU, the ECU gets confused and puts the injection into 'safe' mode. This richens up the mixture at the top end and gives a couple of BHP extra. Anyone confirm this?
Cooperman said:
Now I'm not an expert on injection cars, but I did hear that if you remove the temperature sensor which sends the temp to the ECU, the ECU gets confused and puts the injection into 'safe' mode. This richens up the mixture at the top end and gives a couple of BHP extra. Anyone confirm this?
Safe mode (aka limp home mode) occurs when various sensors fail completely or give out of bounds values. This makes the ECU run a very basic, fixed set of parameters such as fixed timing and fixed engine temperature. This general dosen't help performance
However, there are certain tricks you can do e.g. increasing the resistance of the air temperature sensor which can make the ECU advance the igntion slightly (thinking inlet air is colder). The gains aren't going to be huge though.
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