K series MPG & race tweaks

[TomB]

Firstly, sorry if this has been done before, but search aint working!

 

My 1.4SS / 1996 / no cat coverter / 5 speed / MEMS, ex racer, is returning MPG around 32 miles, which I gather from the specs in literature, is fairly poor for a K series. According to the brochure, i should be getting high 30 or low 40s. I know to treat these figures with a pinch of salt. This is a longish average over about 4 fuels tanks full.

 

Reason I ask, is I have noticed that my race prepped engine has no lamda sensor, a variety of hoses, breathers or vents on the plenium missing or blocked, and it failed the emissions test (although being 96 & kit built he shouldnt have tested it).

 

I was wondering if race tweaks such as removing or blocking breathers might squeeze more power, but ruin fuel efficiency & make it run rich.

 

Suggestions as to what these intake mods might be & whether I should get the ECU reprogrammed to lean the mixture off a bit.

[Chris W]

My 1.8K 140hp is returning just a fraction over 40mpg even when driven hard. (road use only). That's monitoring it by noting litres to fill rather than using the gauge so it should be pretty accurate.

 

Forgive me if I'm incorrect, but aren't you located in the USA or is that another Tom? If so the US mpg for my car would be 33.2mpg which is very close to your figure.

 

Chris

 

1.8K SV 140hp see it here

[TomB]

No I am in Merseyside, but I'll check the conversion. My diary states 1 gallon = 4.55 l.

[Chris W]

Your diary's correct Tom.

 

Chris

 

1.8K SV 140hp see it here

[Lawrence_Z]

The 1400 race engines run very rich at idle due to the large amount of overlap on the cam timimg, and the mems ecu inability to reduce fueling.

This can be remedied by fitting one of those nice Emerald ECU's or reducing the overlap.... but you wouldn't like that

 

Lawrence

[TomB]

So its a compromise then caused by MEMS?

 

An Emerald would cure this, but what about the missing breather hoses, eg. one from the back of the throttle pot to the side of the plenium, and 2 on the engine side of the plenium (one of which is blocked up with rubber?

[Nifty]

I'd be happy with that Tom.

The literature is having you on, my road spec 1.4SS is doing a little over 30 mpg.

 

This drops considerably if out blatting with Bentley Boy 😬 😬 😬

[TomB]

Really Nifty? I thought they were meant to be more than that. Interesting.

 

Does yours have a pipe from the rear of the throttle pot to the plenum? I need to visually compare mine to a road spec engine to spot the differences. Dont suppose you've got any digi pics of that part of the engine?

[Lawrence_Z]

There's vacuum hoses from the plenum to the ECU via the ful trap, and from the plenum to the fuel regulator reference. On my one (no reason for this to be the norm) the one nearest the throttle body goes to the FPR.

There's also the larger breathers to the cam cover. One from the atmosphere (Filter) end of the TB going to the rear cam cover breather. The other quite short from plenum to cam cover.

HTH

 

Lawrence

 

[Sheds Moderator]

My 1.4kss did 34 on a 500 mile trip weekend, most of it on the A1 in top gear at 80 odd mph, so 32 is OK. The book is having you on at 40, unless you are talking constant 56 which I am sure we all cruise at!

 

If you don't like 32 to the gallon then pushing the right hand pedal less hard generally improves economy

[Rob Walker]

It is a bit unrealistic to expect high fuel economy if you are not running with a Lambda probe/closed loop fueling. Also you can only expect high economy if you use a lot of constant throttle motoring, when the MEMS will optimise the fuelling on that contsant throttle setting.

 

Edited by - Rob walker on 28 May 2003 10:09:43