Fuel Consumption with larger Cams on a Boss 260 - Any feedback please

themunz2003 · 06-01-2011, 01:12 AM

A couple of members suggested to touch base with Blue Power as they stated that you know these engines inside out.

I have a BA xr8 that is chewing alot of fuel. It was around 27L/100km and then was up to 32L/100km after another tune from a different performance tuner(no dyno - guess work with flash tuner). Initially when I purchased the vehicle, it was a steady 21L/100km. The engine had been rebuilt before I purchased it and has had an extensive rebuild including stage 3 cams (Crower cams 228/232). Injectors are stock. It was retuned (dyno) again just recently by a different performance workshop and although they got a descent amount of grunt out of it (315rwkw) it is still fairly high with fuel consumption. Around 25-26L/100km.

Any feedback if this is normal for cams this size???

Quadcams · 06-01-2011, 03:23 PM

Definately doesnt sound normal.

My old ute (BA XR8) had GTPX cams (about 330rwkw) and used about 18-20L/100 around town, 10-13L/100 on the hwy.
Did depend at on the right foot, did get higher with spirited driving but on avarage was about the figures above.

Wade

tweeked · 06-01-2011, 03:37 PM

Sounds high, I have stage two Comp cams with 400cc extra capacity, and get 11 on the highway and 20-22 around town. (270 km for 55 litres is the worst I have ever got, all stop start inner city stuff)

cjf · 06-01-2011, 05:46 PM

That sounds very high my built GT 290 averaged 12.3L /100km on my trip to Willowbank Drags and back on monday (approx. 500km).
If I drive it very hard it sits at 28L /100km.

themunz2003 · 07-01-2011, 12:06 AM

Everyone keeps saying it's high but when I get it checked (especially just recently) nothing appears wrong. It is driving me nuts. The performance guy I took it to last said it sounds extreme to chew that sort of fuel but after he tuned it said it was normal due to the 'large cams'!
Love to bring the car in to Blue Power to get it looked at but I'm in Sydney.

Grum · 07-01-2011, 12:25 AM

Make the drive south, you wouldn't be the first and won't be the last.

I'm willing to bet a few beers your fuel economy will be better on the way home!

themunz2003 · 07-01-2011, 01:22 PM

I may hold you to that! lol. I will look into the journey.

JOSH · 07-01-2011, 04:55 PM

how old are you 02 sensors?

themunz2003 · 07-01-2011, 08:32 PM

Had them replace mid 09 (inc alternator - expensive!!) with genuine BF o2's. Had them rechecked mid '10 thinking they may be a problem as someone said they had never seen why someone would solder them in as they're is a connection. Asked auto electrician about it. Feedback was the BF o2's are better - something to the effect of better bandwidth(?????)

StockieXR6T · 07-01-2011, 10:06 PM

Ask whoever is doing you tuning what sort of cruise and part throttle timing you are running, larger cams wash off compression at lower rpm requiring more timing at cruise, part throttle and low RPM, if they don't know or don't touch that area then find another tuner who does more than tune WOT. If the fuel isn't leaking onto the ground and the cars runs in closed loop with good 02 sensors as stated then it is likely low cruise and part throttle timing.

themunz2003 · 07-01-2011, 11:07 PM

He did show me graphs on computer in reguards to timing and spent alot of time remodeling the timing. But then again, I don't know exactly what I'm looking at as I don't have that expertise and knowledge in that area. It makes sense what your saying and appreciate your feedback.

StockieXR6T · 08-01-2011, 01:47 PM

Timing is a 3D map as well, some people spend all their time on WOT. WOT is relatively quick to get right, the part throttles take more time. Most of the tuning I get is retuning work to improve driveability, part throttle torque and economy. Another thing is where the tuner decides to put the car into and out of closed loop.

**Bluepower** · 28-01-2011, 01:44 PM

Quote:

Originally Posted by themunz2003

A couple of members suggested to touch base with Blue Power as they stated that you know these engines inside out.

I have a BA xr8 that is chewing alot of fuel. It was around 27L/100km and then was up to 32L/100km after another tune from a different performance tuner(no dyno - guess work with flash tuner). Initially when I purchased the vehicle, it was a steady 21L/100km. The engine had been rebuilt before I purchased it and has had an extensive rebuild including stage 3 cams (Crower cams 228/232). Injectors are stock. It was retuned (dyno) again just recently by a different performance workshop and although they got a descent amount of grunt out of it (315rwkw) it is still fairly high with fuel consumption. Around 25-26L/100km.

Any feedback if this is normal for cams this size???

munz,

what is your average KPH on the speedo readout??

Chris

themunz2003 · 30-04-2011, 01:35 PM

Average kph is fairly low. Usually just above 40! I have been sussing out a few things on the car since the last post. 1) The fuel filter was backed up with ****. 2) I have put the Weapon X coil packs on 3) replaced the fuel filter again after a tank of fuel has gone thru it. All these things changed dramatically on how the car was performing and with fuel economy. Of late the economy has been creeping back up but is still a few litres shy of the above figures! Around 23L/100. I'm awaiting the fuel pump upgrade and at the same time will send the injectors off to be cleaned and give the tank & link a good flush. I dont think the fuel pump was ever upgraded. Will keep post new figures once this has happened.

themunz2003 · 30-04-2011, 01:39 PM

Once I have sorted this bs out would definitely want to upgrade it with a Kenne Bell kit. Keep me posted Chris with my options and many thanks for your time and advice!