Ray Gamma Posted September 12, 2008 Share Posted September 12, 2008 I'm very seriously considering using my x flow as my 10,000 miles per year daily driver. I've done this in the past, and I'm happy to battle the elements. BUT Is there anything that I can do to optimise fuel consumption? If I can get my MPG between 30 - 40 😳 then this would be an economical and fun alternative to my current lease hire car. I don't really want to consider an engine transplant. I would value your thoughts Rob ETA - I've also posted on ChitChat for advice about sensible / comfort upgardes - here Edited by - Ray Gamma on 12 Sep 2008 17:05:02 Link to comment Share on other sites More sharing options...
Roger King Posted September 12, 2008 Share Posted September 12, 2008 I'm assuming that the engine is healthy to begin with. 3D ignition will make a big difference if mapped well. Not only does it improve efficiency on part throttle, but it makes the engine willing to pull a higher gear in any given circumstance. Assuming that you currently get low 20s, it is likely to give mid to high 20s depending on driving style. Beyond that you are really into full engine management which is much more precise with the fueling, but you will never get a Crossflow to be as economical as a modern 4-valve engine. Don't bother to think about detuning the engine - so long as you keep to a pair of DCOEs the fuel consumption will remain roughly the same. Link to comment Share on other sites More sharing options...
7 Posted September 12, 2008 Share Posted September 12, 2008 I agree with Roger. On a recent 60 mile round trip on mostly motorways, my steel crossflow with Weber Alpha 3d did 33mpg. I was very surprised! If you go 3D and are not affraid of DIY then the megajolt solution is really good. I had one for a while and I prefer it to the Weber Alpha as you can alter the map and other config youself. Link to comment Share on other sites More sharing options...
Ray Gamma Posted September 12, 2008 Author Share Posted September 12, 2008 Thanks for the replies 😶🌫️ The engines very standard (1700), no rebuilds etc, and done about 40,000 miles, I'm not qualified to comment on it's healthiness. What is the ball park cost of such conversions (promise I won't hold you to it )? This is beyond my DIY skills, realiability and good mpg are a priority over performance for this project (don't worry I've got a fast one as well 😬). Now that Roger has retired; where'd you get this sort of work done? Cheers Rob Edited by - Ray Gamma on 12 Sep 2008 16:12:43 Link to comment Share on other sites More sharing options...
New Cat Posted September 12, 2008 Share Posted September 12, 2008 With a little help from a few fellow Seveners I would expect to fit a Megajolt setup for £200-250 and this includes using many of the bits that make life easier such as the genuine Weber Throttle Position Sensor. Best to start collecting the bits and then collar whatever help you're left needing... I can vouch for it being very good but you will lose most of the pops and bangs ☹️ 😬 Jon 1994 1.7 Supersprint De-dion X-Flow. Yellow with black cycle wings - Now with Megajolt ! Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted September 12, 2008 Area Representative Share Posted September 12, 2008 Ray 1:- Roger knows what he is talking about and has forgotten more about Crossflows than most of us will ever know... but... 2:- I have been thinking about the same issue (with respect to GJT the crossflow) and talking to Oliver Sedlacek at Penn Sevens, he said that the biggest difference to fuel economy for his crossflow was the replacement of the standard item with forged pistons. This, he explained, is due to their lighter weight; lowering the mass of the bits you are pushing around in the engine makes a difference. It's worth noting that Oliver was using the Crossflow daily at the time (he has a 120,000+ miles on the clock to demonstrate this) Having said that he also put in 3D mappable ignition subsequently and says that he now can achieve 30+mpg (approx). I intend to have an engine refresh done on GJT soon (spring next year I think) and plan to have both forged pistons and 3D ignition at that time. GJT has done over 90,000 miles and was, in the past, used as the daily commuting car. Having moved house and started freelancing, I now don't have a regular commute but use the train when I travel into London (my most regular destination). The other reason GJT is used less often is that I bought 524 (my 21 ) which is more economical on fuel despite now having a VHPD under the bonnet. Democratic dissent is not disloyalty, it is a positive civic duty. Edited by - Golf Juliet Tango on 12 Sep 2008 17:44:26 Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted September 12, 2008 Area Representative Share Posted September 12, 2008 Ray I am aware that you are in North Yorkshire but I am a long term customer of Ratrace/Protune and they would be an excellent choice for your Crossflow work. Protune or Ratrace Democratic dissent is not disloyalty, it is a positive civic duty. Link to comment Share on other sites More sharing options...
6speedmanual Posted September 12, 2008 Share Posted September 12, 2008 Longer gearing would almost certainly help with economy if you can find suitable combination of gearbox and rear crownwheel and pinion. P 6SpeedManual *tongue*There's no such thing as too much BHP per Ton 😬 Link to comment Share on other sites More sharing options...
Ray Gamma Posted September 12, 2008 Author Share Posted September 12, 2008 Great advice - keep it coming. What would be the stages (equivalent to performance stages) for reliability / mpg tuning in a x flow, i.e can all those expensive sounding, internal upgrades be a sensible upgrade, or are they just good for highly stressed, high maintenance race engines? Rob Link to comment Share on other sites More sharing options...
john g Posted September 12, 2008 Share Posted September 12, 2008 How about ... remove the twin 40's and replace with a 28/36 or 32/36 carb ... oh and a manifold and bonnet. Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted September 12, 2008 Area Representative Share Posted September 12, 2008 6Speed has a good suggestion on ratios:- Do you have an Ital axle? I understand that there is demand (from race/sprint drivers) for 4.11 diffs. If you replace with 3.89 or even 3.63 you will loose acceleration but gain in mph per 1,000 rev. Equally adjust your driving style (but you may have done this already) Democratic dissent is not disloyalty, it is a positive civic duty. Link to comment Share on other sites More sharing options...
Pezky Posted September 13, 2008 Share Posted September 13, 2008 not sure on the 6-speed gearbox, 6th in the caterham box (designed for high revving k-series)is equivilant to 4th in a 4/5 speed box. Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted September 13, 2008 Area Representative Share Posted September 13, 2008 No, I am not saying put in a six speed 'box - I am agreeing with Peter (6speedmanual) Democratic dissent is not disloyalty, it is a positive civic duty. Link to comment Share on other sites More sharing options...
Irrelevant Posted September 13, 2008 Share Posted September 13, 2008 *idea*Borrow some bigger rear wheels and see if the gearing chance makes much difference before farting about changing axles and boxes....Not sure it will make much difference for 70mph cruising though. If you gear it too high, it won't have the torque to pull the high gearing at cruising revs. Link to comment Share on other sites More sharing options...
Pezky Posted September 13, 2008 Share Posted September 13, 2008 Sorry GJT Must read posts a bit more carefully Link to comment Share on other sites More sharing options...
Setok Posted September 14, 2008 Share Posted September 14, 2008 Interesting thread... If 3D ignition is used, can that still be used with a Zetec upgrade, if one would want to go down that path at some point? --- Kristoffer Lawson Link to comment Share on other sites More sharing options...
eric Posted September 15, 2008 Share Posted September 15, 2008 my 1600 sprint 110 HP is 28 / 30 mpg only an aldon with ignitor choke 30 main 120 air 180 F16 idle jet 50F9 if you want something like 30 /32 mpg replace twin webers with the vertical weber Link to comment Share on other sites More sharing options...
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