na mpi tuning
Turbo Mini Forums

hi, this post isnt anything to do with turbos. but as there is quite a bit of knowlege in this forum i might as well give it ago

...whats the best performance i can get from an mpi with standard bore size/injection?

was thinking a 274 cam, rockers bushed to aprox 1.4 ratio(which i already have), k+n induction, and maybe a head skim? and decent exaust system.
think i would put this with sc drops and performance clutch.
any thoughts would be appreciated, thanks

would this lot work together with the standard injection, and what power do you think it would give? thanks

to be honest i've spoken to a few people before and they all seem to say that you cant get much more power out of a MPI with out dumping the injection.

a friend of mine fitted a flowed MG metro head, rockers, air filter, exhaust power boost valve mild cam and i think its about the same as before. could be 5 bhp more or even less. its gutless.

its for my dad, his engine runs so nice and its v low mileage so wants to keep the mpi really. he doesnt want it to be ultra quick, just a bit quicker than it is now. thanks for the reply though. anyone else have mpi tuning experience?

To my mind it's never going to be a power monster as they don't rev due to the method used for injection.

What you can do thiough is improve the mid range torque, which in the real world is far more important than a number on a dyno sheet.

Every day is a school day ...........

How fast and how expensive ...... the same question...

Roger / Turbo Shed - have either of you owned and tuned an mpi? Not being rude but if not then these posts are just hearsay that i've found on every forum to do with minis.

Cos the "they dont rev cos of the method used for injection" is complete rubbish mine pulls like a train from 3k to the limiter at 6.7k

In reply to Welsh Dan -

I have an Mpi and if you stay standard bore no you will never make massive power but its the same with any mini na standard bore.

I would reccommend as i have these on mine - but this doesn't mean it would work as well on yours -

SW5i cam
Stage 4 head
1.5-1 rockers
PBV
Shorter diff ie. change from 2.7 to either 3.1 or 3.44

Hope that helps.

And sorry if anyone thought i was being off there. it just really gets my goat when people say things along the lines of "well i spoke to a few people and they say..." esp. when its not true.

Cheers

TurboDave said

"Fab's right of course.

Maybe you should take your styling ideas off the French instead! "

ok, sorry. i should have been more clear.

MPI minis are slow. changing the head and cam will give about 5bhp if your lucky. get an exhaust and air filter and atleast it will sound fast.

changing the final drive is the best thing you can do. John cooper did this in his 90bhp conversion. the cars never had anywere near 90bhp but they felt better due to the final drive change.

Have you got any figures Dev.

"Pulls like a train" is a little wishy-washy as a statement.

It's just I've heard people say their car pulls like a train before, and then they only manage a mid 17s 1/4mile run. which is pretty average (my 998 will do that).

Any decent 1380 should run 15 or 16s IMO.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

nitrous or a blower kit from vmax

I have wil

98 bananas and 98 curley wurleys

I ran 18.3 at avon last year, granted that is slow BUT in my defense it was my first ever go and i was so hungover i am not sure i should have been driving in the first place. But i didn't think it was that bad for std bore.

JC never sold the conversion with the diff change AFAIK. Well it wasnt an option back in '03 when i first looked at doing my old mpi.

Granted an mpi will never be as quick as a turbo etc but a well sorted one driving well will always be quick and far from slow. Anyway lets not turn this in to a TMF/MF style bitch fest and just provide Dan with the info.

TurboDave said

"Fab's right of course.

Maybe you should take your styling ideas off the French instead! "

Dev, I understand what your saying and agree with you 100%. I have never owned one but have done engine work for a good friend. When we were done we had 87BHP and a really nice flat and solid torque curve .... just the sort of thing you want for back lane overtacking. To be fair I love that car and if she ever sells it (not likely!!!!) I would make sure it was to me!!!

The mods were;

274 MPi cam

Head was ported and matched to manifolds, std valve sizes on 3 angle seats, chambers matched, CR10.5 IIRC.

Bottom end was standard bore (only done 22k when we did the conversion) but was reshelled and balanced properly.

Windage tray fitted

Aweful oil pump replaced.

The inlet manifold was matched to the throttle body.

Maniflow exh manifold and PlayMini twin box system used.

Uprated filter fitted to standard air box (can't remember which one ...)

Gearbox was checked over and was all in good condition so was left other than fitting a 4 pin diff and a 2.9 final drive (car does plenty of motorway miles).

The result was a loverly car to drive, once MEMS had got used to running that engine ....

No matter what you think or how the car feels the MEMS system can not really hold on to optimum fueling much past the late 4s early 5s x1000 rpm. It's all to do with the way the charge robbing effects the fuelling and the scope for being able to inject the "optimum fuelling". Don't get me wrong the engine doesn't rev like a diesel but it's just not running as well as it could. This is the reason I went the way I did with her engine, all torque low and mid range.

Every day is a school day ...........

How fast and how expensive ...... the same question...

Nitrous in ok but limited range for usage and insurance can be a real problem.

Supercharging works, or at least seems to, as it will bulk up the mid range nicely rather than trying to produce power at high revs.

However I got the impression welshdan wanted to stay NA by his opening comment.

Every day is a school day ...........

How fast and how expensive ...... the same question...

welshdan, I'd not think it necessary to put SC drops in and the best of the verto clutches will do just fine.

I would consider going to a 4 pin diff and slightly lowering the raising drive ratio (2.9 works with lots of torque, 3.1 for a milder build)

Every day is a school day ...........

How fast and how expensive ...... the same question...

18.3 seconds.

we took a crappy old 1ltr nissan micra to avon and got a 19 second run

we also took a mini with an almost standard MG metro engine so estimate about 80bhp and that did 15.5 seconds

I did say i was hungover didn't i??

I know i can go faster mate. Just in that heat i had to go lie down like a big girl.

I'll be back this year just it wont have the same engine fingers crossed.

Ah you see i dont have mems hence why mine is different, to your friends.

Having tried a 3.1 and a 3.44 i think i would have gone 3.1 had i considered how much motorway i would be using but the 3.44 is brilliant. IMO

TurboDave said

"Fab's right of course.

Maybe you should take your styling ideas off the French instead! "

18.3 isn't much off where i'd expect that to be tbh. If you get that down to a 17.4 you should be pretty pleased with yourself. I'm assuming it's still in full road trim with 13"s and not stripped at all?

15.5 is very impressive from a 1275 mini, but hardly typical of the performance you can expect is it? A lot of the turbos were clocking in at over 16 seconds.

Yeah full road trim, inc 13's and a fat driver, well not fat but well built shall we say.

TurboDave said

"Fab's right of course.

Maybe you should take your styling ideas off the French instead! "

thanks for the replies. was just thinking along the cam changing lines as he is going to change the clutch soon and he can swap a cam in a few hours whilst the engine is out. and as for the rockers, they can be changes with the engine in the car obviously. he was just wondering about the cam just to give it a bit more bite and as it doesnt take too long...

why would you take the engine out to change the clutch?

if your taking it out, i would change the diff for a 3.1

cos with all the gubbins in the bay its easier to take it out for the first change and after that if you leave the 7 o'clock bolt out they can easily be done in car.

dev

TurboDave said

"Fab's right of course.

Maybe you should take your styling ideas off the French instead! "

we ususally change clutches with the engine in, with the one side jacked up. but as it would be halfway out anyway...

you can buy a replacement ecu from emerald which is totallty re-mappable, im sure vmaxx scart uses it on their mpi supercharged conversions which take the bhp to around 145ish and the ecu still uses the origional sensors on the engine!

VMAXX Scart use a 'wet' manifold on their supercharger kits.

The emerald is indeed MEMS plug and play, however, theres still the port robbing issues on the five port A series

hi, i know this is an old post, but how much are these ecu s? do they have a website? thanks

Gooooooooooooooooooooogle-

Emeraldm3d

Just getting my evil little mits on an MPi lump to tune and run in Candice's Mpi.

I am going to keep the Mems initially just to prove to myself what level of tune it can actually correct the air-fuel ratio with. I know it can live up to 87bhp from my friends engine and I believe Sprokcket got to the magic ton on his Spi but as that is a different control stratergy I think we have to discount that level in an MPi.

After that I will be running Jean's MegaSquirt code to help test and prove out that (hence why I am doing it with a spare engine .. .lol) ..... actually don't tell Candice but that is why I bought the seven in the first place .... not the selfless gift she thought it was ..... lol

Every day is a school day ...........

How fast and how expensive ...... the same question...