8 replies to this topic

[LeeDJC]

I'm looking at tuning an SPi engine in a mini that I'm getting shortly, what's the best options to start with in regards to exhaust, filter etc? Looking for something loud, but which won't decrease power.

[Don't Panic]

If your choosing an exhaust to give a nice 'note' i'd reccomend going to see your local club as its quite hard to tell how loud an exhaust will be.

A single box exhaust has just one silencer (the backbox) and a straight through pipe to the cat. This will be loud and go for a RC40 or Maniflow center or side exit.

A twinbox exhaust will be quieter as it has two silencers, again RC40 or Maniflow

The other consideration is the diameter 1.75" is ideal for performance. The manifold you use will also make a difference. Best to see whats on the car before deciding these things may have already been changed.

I have a LCB manifold and a 1.875" twinbox centre exit maniflow exhaust and it sounds lush! having 2 silencers doesn't mean its silent; you can hear it in the car, it just doesn't hurt my eardrums.

[AlexM]

Get a Maniflow Injection LCB, a K&N element air filter and an RC40 exhaust.

[MinipixMatthew]

Unfortunately there isn't a huge amount you can do with the SPi engine, you're pretty much just limited to exhaust and air filter choices. Unless you want to go dabbling in altering the ECU, but I've not heard of people normally bothering to do that, I suspect the gains in power won't be worth the hastle reprogramming it!

I've got an SPi engine in my Sidewalk, which at the moment has a K&N air filter replacement and an RC40 cat back exhaust. The power difference isn't huge, I have to admit, but it does seem to accelerate more comfortably now. It certainly doesn't feel at all under-powered, and motorway cruising is fine. Before I put the K&N in I was getting 52 bhp, which is fairly respectable, but nothing special. Putting the whole stage 1 kit on in one go might do you some good, as you'd notice the power increase immediately! Exhaust and air filter are the easy ones, manifold is slightly more demanding as it requires taking bits off the engine so you can get to it.

Besides that, you're looking at making better use of the power you've got. Lightening the car can help, and getting some good wheels on will probably help traction and ensure that the power gets to the black stuff! I always notice how much faster my Mini goes when I haven't got a passenger - if you can take out the weight of a person in terms of unnecessary bits of the car, you're gonna notice it. For instance, if you know you're not going to be taking passengers, take the back seats out, don't fill the petrol tank up to full, cut holes in metalwork (as long as it's not structural), leave the spare wheel in the garage, and don't install a massive bass woofer!

[who_loves_the_mini?]

i think the ecu limits power to around 80-85 bhp before you start needing to swap for carbs or mess around installing a new ecu

new exhaust, air filter (standard air filter housing with holes drilled in it and replacement filter seems the best way) uprated head "stage 3" etc and a new cam should give it a bit more poke and be more fun to drive

[m3ntalist]

Mini Sprocket is the man for the Spi!

ive currently got a 274i cam, k&n, maniflow lcb, cat removal pipe, rc40 single box

isnt massive quick or anything but drives nicely

next I need to uprate the suspension before going for extra power I think....

[Bounce]

Unfortunately there isn't a huge amount you can do with the SPi engine, you're pretty much just limited to exhaust and air filter choices. Unless you want to go dabbling in altering the ECU

Not strictly true, you can do pretty much anything to an SPI as you can to any engine. Its just a matter of how far you want to go and what your budget is.

With mine Ive got Stage 1, SW5 cam, 1.5 Roller rockers and double valve springs. And theres a hell of a difference between mine and my friends stage 1 SPI.

Without touching the ECU you can have different cam profiles, different stages of head, uprated throttle bodies, a bigger bore injector. Then you can go into changing the displacement, crank, flywheel work, and maybe even forced induction! The list gose on, again, its all about your budget.

Take a look at Mini Sprocket's last project, the spec for his SPI engine, is quite impressive!

[Faultless]

will removing the cat make much difference to the noise or performance

ive seen im mini mag that the cat makes little difference to injection minis altho i think that was mpi not spi.

are the cat removal pipes hard to fit thanks Lee

[Bounce]

It'll certainly make your exhaust louder, possibly even give you a little bit more performance. But seein as you need the cat fitted by law due to the age of the car, youd be running the risk of trouble from the police!

Just stick to legal mods, declair them on your insurance and you cant go wrong.