Fuel Consumption

Simeon · Post by **Simeon** » Tue Apr 10, 2012 8:39 pm

Ok Chaps
I have a RV8 3.5 in a Westfield. It has a piper 270 cam and an Edelbrock 500 carb. I gave it to Janspeed in Salisbury to play with and to be fair it goes like the clappers however it goes through way too much fuel. I've worked it out to be between 10 - 15 mpg and that's driving it conservatively. I noticed tonight that it back fires now again whilst foot off the throttle. I assume it's running very rich. My knowledge of tuning engines is nill and was wondering if there was anything I could do to improve the mpg?

ChrisJC · Post by **ChrisJC** » Wed Apr 11, 2012 6:59 am

I would fit a wideband lambda sensor with in-car readout. Then you can monitor the mixture over all driving conditions to see if there are any issues.

Chris.

DaveEFI · Post by **DaveEFI** » Wed Apr 11, 2012 7:59 am

It's all to easy to get an engine to 'go like the clappers' by making it run rich at all times. Hence the diabolical fuel consumption. The real skill is retaining that performance while giving good economy when you're not using full power.

sidecar · Post by **sidecar** » Wed Apr 11, 2012 10:36 am

DaveEFI wrote:The real skill is retaining that performance while giving good economy when you're not using full power.

....Which is possible with an Eddy 500 if you sort out the jetting and get the ignition setup correctly.

kiwicar · Post by **kiwicar** » Wed Apr 11, 2012 2:57 pm

Hi
Back firing is generally a sign of an air leak into the exhaust, (or a very lean mixtue on overrun) not really a sign of an over rick mixture. . . . flames out the tail pipe is a sign of a very rich mixture

.
As said above the skill is to get it to go like the clappers and and return good economy when not applying the boot.
Best regards
Mike

Simeon · Post by **Simeon** » Wed Apr 11, 2012 4:37 pm

OK
So who would be the best person to take my car to, to maintain the performance whilst giving better fuel economy.

With todays fuel prices a trip to a specialist would pay for itself within a week.

kiwicar · Post by **kiwicar** » Fri Apr 13, 2012 9:47 am

Hi
To be honnest your best bet to get this set up well would be to do as Chris surgests and get a wide band lambda sensor (an inovate LC1 for instance) and a gauge and fit it, then note the results. Post the results on here and there are several chaps on here (muscle manta, sidecar & spend for instance) who are very knowlagible on setting up 4 barrel carbs and can help you with recommended set ups based on the information you get from the lambda sensor. You have a base line set up that you know goes well to work from, you just really have to lean out the cruise, maybe back off the full throttle a little and you will be there, the lambda sensor and a stopwatch will tell you the effects of anychanges and the guys on here will tell you what to change.
Best regards
Mike

Eliot · Post by **Eliot** » Fri Apr 13, 2012 11:51 am

the problem with fitting a wideband is that you will quickly realise how crap 4 barrel carbs are and want to replace it with fuel injection.

DaveEFI · Post by **DaveEFI** » Fri Apr 13, 2012 12:19 pm

It could be because they are the market leader, but I see lots of reports of problems with the LC1.

Eliot · Post by **Eliot** » Fri Apr 13, 2012 12:21 pm

Indeed - i've used a Zeitronix and seems well built.

http://www.zeitronix.com/

DaveEFI · Post by **DaveEFI** » Fri Apr 13, 2012 1:05 pm

Eliot wrote:Indeed - i've used a Zeitronix and seems well built.

http://www.zeitronix.com/

As is my Tech Edge - but then I built it myself.

ChrisJC · Post by **ChrisJC** » Fri Apr 13, 2012 3:54 pm

I've got an Innovate LM1 which I am happy with. It is obsolete though, so I can't say if the newer Innovate stuff is any good.
I've hooked it up to my MJLJ so the MJLJ logs Lambda value as it's aux signal. Very interesting!

Chris.

JSF55 · Post by **JSF55** » Fri Apr 13, 2012 9:58 pm

ChrisJC wrote:I've got an Innovate LM1 which I am happy with. It is obsolete though, so I can't say if the newer Innovate stuff is any good.
I've hooked it up to my MJLJ so the MJLJ logs Lambda value as it's aux signal. Very interesting!

Chris.

JUst done mine too, shows how poor a carb can really be ! but at least i'm getting 22 mpg !

sidecar · Post by **sidecar** » Sat Apr 14, 2012 8:17 am

Carbs don't have to be crap, Muscle Manta and I have spent along time setting up his webber 500, His car also runs an MSD ignition system with a MAP system for the vac advance. Get this, 27 MPG from a stage III 4.6 running at motorway speeds!

Cobratone · Post by **Cobratone** » Sat Apr 14, 2012 11:38 am

sidecar wrote:Carbs don't have to be crap, Muscle Manta and I have spent along time setting up his webber 500, His car also runs an MSD ignition system with a MAP system for the vac advance. Get this, 35 MPG from a stage III 4.6 running at motorway speeds if it had a good efi system!

Fixed it for you Pete