Peter Carmichael Posted August 4, 2007 Share Posted August 4, 2007 Today, I drove my Seven 35 miles and it took 4.4 litres to fill it up again (fuel level showing in the filler neck). This was no accident. I've been refining the map successively to get the fuelling as close to spot-on as I am able to achieve using a wideband lambda setup. For many years, I'd not achieved decent fuel economy from a throttle bodied installation of the engine. I'd not been convinced there was any good reason apart from poor/partial setup/mapping that caused poor fuel economy. Today's configuration... ... had no flat spots or hesitation ... had no kangerooing ... had no poor manners ... maintained lambda between 1.0 and 0.9 except on overrun when a fuel cutout was implemented ... ... and pushed out 250 bhp 😬 The 35 mpg run included full throttle fuelling tests (still refining this area of the fuelling), and a fair bit of pootling about. Fuel economy will plummet when the setup is used to its full potential, but I am gratified that I'm not burning money for the sake of it. Link to comment Share on other sites More sharing options...
stevefoster Posted August 4, 2007 Share Posted August 4, 2007 Yeah, I've been playing about with mine for ages to get it as sweet as possible. I still have a slight spot of light throttle where a little more fuel is needed. Break out the lappy again. Hants (north) / Berkshire club here Area meeting pics here My Racing here Link to comment Share on other sites More sharing options...
rj Posted August 5, 2007 Share Posted August 5, 2007 Well done Peter! Link to comment Share on other sites More sharing options...
oilyhands Posted August 5, 2007 Share Posted August 5, 2007 Peter, Nobody likes a smart-arse 😬 Well done, kind of satisfying when you get something so obviously right. Oily Link to comment Share on other sites More sharing options...
Billyboy Posted August 5, 2007 Share Posted August 5, 2007 *eek* *eek* *eek*35mpg *eek* *eek* *eek* *eek* *eek*250bhp *eek* *eek* *eek* *eek* *eek*blimey *eek* *eek* *smokin* *smokin* *smokin* take a bow! lucky if I get 25 mpg from my 165bhp R300 WELL it is an SV Link to comment Share on other sites More sharing options...
Bloggsy Posted August 5, 2007 Share Posted August 5, 2007 Hmmm.... 35mpg, 250bhp therefore if my pretty much standard 1.6 SS has 135 Bhp I should get... ermm... just under 65mpg. I just haven't got enough horses per gallon ☹️ P.S. Well done. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 5, 2007 Author Share Posted August 5, 2007 This has not been an exercise particularly to achieve good fuel economy. I just wanted the fuelling to be as good as possible and I've used every trick and tool available to me to work on the fuelling. The starting point was to translate a map from Emerald format to EFI-Tech format. The EFI-Tech ECU came with the wideband kit and with some experimentation it has been very good at refining the general running settings. I've had to come up with different strategies to explore the high throttle opening settings and the high rpm/large throttle fuelling is now settling down. This is giving me the confidence that the high power fuelling is not bore washing, but has a bit of extra fuel keeping the cylinders cool. Up until yesterday's test runs, lambda had been dropping to 0.8 and below on large throttle opening, but I've been able to trim it to 0.85 in the course of a couple of test runs. The NTK sensor I'm using is quick reacting enough to measure transient fuelling - this is the final challenge. For all that a rolling road session is a great and necessary way of getting the majority of engine running settings right, there is nothing like getting feedback directly from the engine in the real world. The process is iterative. You'd go bankrupt trying to do all the development work on a rolling road. Link to comment Share on other sites More sharing options...
Bilbo Posted August 5, 2007 Share Posted August 5, 2007 Peter Looks like you getting OLD and not using your right foot enough Having said that bloody hell ❗ 😬 impressive 😬 I have manage 25+ mpg on a slow run out of town with care, actually that was when last 'running in' and long run driven hard between 21.5 and 22 mpg but that's carbs with mapped ignition. Track........... 🤔 'Can you hear me running' ......... OH YES and its music to my ears 😬 😬 😬 1988 200 bhp, 146 ft lbs, 1700cc Cosworth BD? engineered by Roger King, on Weber's with Brooklands and Clamshell wings, Freestyle Motorsport suspension. Link to comment Share on other sites More sharing options...
Pat the Plumber Posted August 5, 2007 Share Posted August 5, 2007 R400, 70miles on the clock, only 14 litres left on the gauge , 212bhp..... 😬 makes me want more power so i can get more miles to the gallon Duratec is the way forward!! Link to comment Share on other sites More sharing options...
Powderpuff Posted August 5, 2007 Share Posted August 5, 2007 Have you bought a new toy Pat?? Link to comment Share on other sites More sharing options...
Irrelevant Posted August 6, 2007 Share Posted August 6, 2007 I drove my Seven 35 miles and it took 4.4 litres to fill it up again Well as there are 4.54 litres to the imperial gallon, you actually achieved 36.11mpg . . . . Well someone had to point it out Link to comment Share on other sites More sharing options...
Mark Durrant Posted August 6, 2007 Share Posted August 6, 2007 Peter Why not bring it to Curborough and prove how quick it is. Keep your ACB10's, enter in Class 6 and take on Alex Wong and DaveyBee Mark D Comp Sec Link to comment Share on other sites More sharing options...
Irrelevant Posted August 6, 2007 Share Posted August 6, 2007 Why not bring it to Curborough Indeed - Would be nice to see it As it should only use 7.93 gallons to get there and back, it should be a cheap day out as well 😬 Link to comment Share on other sites More sharing options...
dannylt Posted August 6, 2007 Share Posted August 6, 2007 Peter - isn't the issue with high rpm/wide throttle that you can only know from a dyno what mixture is actually giving you best power? But for part throttle it sounds great - I need to do the same! Link to comment Share on other sites More sharing options...
S47zz Posted August 6, 2007 Share Posted August 6, 2007 What is a good first adjustment too make to achieve better economy on TB setups? My car was set up by DW at emerald, it's pretty good but I'd like to improve the motorway 'cruising' light throttle running economy if possible any suggestions?? Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 6, 2007 Author Share Posted August 6, 2007 Can't do Curborough. I'll be mountain biking in the Alps. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 6, 2007 Author Share Posted August 6, 2007 isn't the issue with high rpm/wide throttle that you can only know from a dyno what mixture is actually giving you best power No. Peak power is fairly predictable, with AFR down to 12.5:1 (lambda 0.85) used to keep in-cylinder temperatures reasonable, with very little variation in power. The wideband lambda sensor I am using is the old-school NTK item. This is a fast-switching unit which means you don't get caught out with mis-readings when the engine operating needs are changing quickly. Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 6, 2007 Author Share Posted August 6, 2007 it's pretty good but I'd like to improve the motorway 'cruising' light throttle running economy if possible The first thing to do is to look at the graphical view of the fuelling map. Chances are it is quite a spiky affair. I'm going to get myself in trouble now... (as anyone does when they state generalities with regard to engine mapping, a process that can lead to broken engines if done without sensitivity). ... a spiky fuelling map is wrong; cannot be right; is the result of believing a number on a computer screen rather than thinking about the requirements of an engine. How can a spike in the fuelling possibly be right... if you are having to rely on bald luck that the spike happens to coincide with a load site/speed site? Fuel injection maps are subject to the limitations of digital sampling, as stated in the Nyquist-Shannon sampling theorem:The sampling theorem means that uniformly spaced discrete samples are a complete representation of the signal if and only if the bandwidth is less than half the sampling rate. Spiky maps are wrong. Rolling road operators tend to believe the numbers their expensive machines tell them. You get a spiky map out of a rolling road session and it is wrong. Edited by - Peter Carmichael on 6 Aug 2007 14:21:02 Link to comment Share on other sites More sharing options...
paulyb Posted August 6, 2007 Share Posted August 6, 2007 Having just had a great little run in Peter's car on a few of the local roads and most importantly roundabouts 😬 I can certainly testify to the refinement of Peter's set up. Spinning smoothly all the way through the rev range from pottering along in sixth at 1800 revs to maximum acceleration around and out of the roundabouts Most impressive is the tractability of the engine - dawdling along in sixth at little above idle you can floor the throttle and accelerate away with none of the usual stuttering and kangarooing which that usually produces. .....and the neatness of the wiring under the bonnet means I'll be too embarrassed to ever remove my bonnet and exposed the mass of multi-coloured spagetti ever again 😳 Genuinely puts all the installations I've seen previously in the shade Link to comment Share on other sites More sharing options...
S47zz Posted August 7, 2007 Share Posted August 7, 2007 Peter Thanks for the advice I'll check out the fuelling graphs when I get a spare evening *thumbup* 😬 Link to comment Share on other sites More sharing options...
Swiss_Tony Posted August 7, 2007 Share Posted August 7, 2007 Peter I am concerned that there is something wrong with my car/mapping 😳 I went out for a blat the other week with another 7 and over the 200 mile journey returned a tad under 40mpg Dont even think of suggesting the possibility that I was driving like an old woman James Su77on Se7ens Link to comment Share on other sites More sharing options...
Dickie Normuss Posted August 7, 2007 Share Posted August 7, 2007 ah, but were you in the 7 VX HPC - Loud and proud here Watch out, whatever hits the fan will not be distributed evenly Link to comment Share on other sites More sharing options...
Swiss_Tony Posted August 7, 2007 Share Posted August 7, 2007 ric My tin top has been known to drop to 6or7 mpg during enjoyable driving Out of interest have you painted your calipers on your new tin top 😳 I would consider a diesel but as the old saying goes:- "Owning a diesel is like being gay. Its becoming more accepted but its still wrong 😳" James Su77on Se7ens Link to comment Share on other sites More sharing options...
Peter Carmichael Posted August 7, 2007 Author Share Posted August 7, 2007 Dont even think of suggesting the possibility that I was driving like an old woman Tempting, tempting... I'll settle for: ... if people are getting poor mpg from their mapped, throttle bodied engines, there is something fixable that is wrong. If there are flames coming from the exhaust and a strong whiff of petrol that might be a starting point for investigations. Link to comment Share on other sites More sharing options...
caterhamnut Posted August 7, 2007 Share Posted August 7, 2007 *arrowup*Kill joy 😬 www.mycaterham.com here Videos here 101,000 miles car Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now