Go-Faster Fuel Economy

[danmason]

In a recent post Fen mentioned that fitting a MAF to his Turbo resulted in a decent increase in fuel economy. Well, over the next couple of years it's likely I'll be carrying out some tweaks performance-wise and it's interesting to me that certain upgrades could in some way counteract the negative economy aspects of others. And with our ridiculous fuel prices going nowhere but upwards, fuel economy is fast rising on my list of considerations.

I'm sure some of you have plenty of general advice around the economy implications of various performance upgrades - I'm all ears! []

 

[John Sims]

Our beloved 944's are IRO of 15 years old now and use technology older than that. Cars have developed over the years and elements are replaced for those that are more efficient. MAP & MAF come under that heading. Both systems do away with the restrictive Air Flow Meter "Barn Door" and clean up the induction as a result. If the system is functioning correctly it should both provide better performance and better economy.

The big issue here is "If". All modifications are a bit hit and miss. There aren't that many modified 951's in the overall scheme of things. Add to this that everyone modifies their cars slightly differently and each modification is then next to unique. Even purported turn key solutions maybe of limited quantity and equally limited proving.

Engine modification is a bit of a black art. What works on one car may not work on another for all manner of unrelated reasons. If it was easy, anybody could do it. []

I'm not trying to put you off but, from personal experience, as soon as you start changing things you are on the slippery slope to potential poverty. Modifications are expensive and hide all manner of extras. You will never recoup the expenditure in greater fuel economy. If you want an economical car sell the 944 and buy a Ford Focus, or a Seat, or VW or anything modern.

 

[Fen]

I think John has a point, but then again where's the fun in a Focus? Coincidentally the very MAF (and chips to go with it) that took my car from 360 miles on a tank up to 410 is sitting in my garage feeling unloved... To be fair I did have a top end rebuild and a recon turbo (also in the garage feeling unloved) and a TiAL wastegate fitted at the same time.

 

[sawood12]

Well i'm chuffed to bits with my 25 or so MPG I get from my turbo especially when it appears to be pretty insensitive to how I drive it. Mates who have hot hatches (Cupra R's, Type R's, TT's etc) can get well into the 30's mpg but mostly get low 20's as they don't tend to drive in the most economical way (usually because they are trying to keep up with me!). On trips with my mates my 17 yr old 944 compares admirably to the fuel economy of modern and more advanced machinery, especially on the motorway thanks to it's more areodynamic shape. And it certainly isn't lacking in the perfomance dept.

So far i've barely dipped my toe into the world of performance mods with a dual port wastegate and ESS exhaust giving me 237.5bhp at 0.8 bar boost, but am forcing myself to stop at that. The only mod I can see myself investing in now are Guru chips (or MAP sensor and chips if I decide to push the boat out). Having said that i've promised myself that if or when my turbo goes i'll replace it with one from a 250bhp 944 turbo. Much beyond that I feel you are getting into the territory of the law of diminishing returns. As much fun as the modding game is (and it's certainly tempting) i'm managing to resist the temptation.... so far.

 

[eastendr]

Quite right.

Modified cars are the work of SATAN [][][]

 

[danmason]

I'm not trying to put you off but, from personal experience, as soon as you start changing things you are on the slippery slope to potential poverty... You will never recoup the expenditure in greater fuel economy. If you want an economical car sell the 944 and buy a Ford Focus, or a Seat, or VW or anything modern.

Thanks for the words of caution John, very true but I don't want an 'economical' car per se, nor to recoup my outlay - just to ensure I preserve most of the fuel economy I get at the mo. Non-Porsche motoring is not something I fancy, having driven enough modern cars to know that Porsche were making 'em better (and much more fun) 20 years ago! [8D] For around-town motoring, where the Turbo guzzles the gas, I go with the 924.

I should probably also have added that I'm mainly looking at subtly upgrading through replacement of tired components rather than an obsessive faster-faster mentality. My car's wonderful as it is, pushing out 250bhp and virtually lag-free with the BlitzChips and Boost Enhancer, but after 30k miles one does become sensitive to its few foibles.

I'm sure a new wastegate & turbo would tidy things up nicely, but a MAF kit does seem like an appealing option. Unfortunately though Fen I won't be in the market for one for around 6 months [&o]

 

[944Turbo]

Much as I would like to encourage you down the modded turbo route - and economy is a good excuse as any [] - unless you do a lot of miles, any gain is likely to be offset by increased insurance.
Tony

 

[Guest]

Whatever mods you do, you'll never get your money back unless you do massive annual mileage.

Case in point: LPG is £1500-£2000. You need to do around 20,000m to get your money back. (NA) Who knows if it's Turbo compatible?

Case in point: economy spark plugs - how many miles do you have to do to amortise the extra cost?

Having lost lots of sleep by pressing too many calculator buttons, I then bought a second car just to cheer myself up!