cam vs mpg
06-01-2011, 06:59 AM
#4
Great topic, i am heavily thinking of yanking the LQ4 with the Trex out of the 89 RS in favor of a 5.3 with a tiny cam and 112 LSA along with a 750 VS to see if i can hit 30
MPG, i no longer street race so having a 6 speed street car is dulling down with so much lack of streetability, if my 5000 pound stock 5.3 powered trailblazer that is a moving brick gets 22 MPG on the highway, my 3150 pound aerodynamic 6 speed RS should get 30 or so i think.
MPG, i no longer street race so having a 6 speed street car is dulling down with so much lack of streetability, if my 5000 pound stock 5.3 powered trailblazer that is a moving brick gets 22 MPG on the highway, my 3150 pound aerodynamic 6 speed RS should get 30 or so i think.
06-01-2011, 06:33 PM
#5
I have the HT1 cam in now. And i have the lq4 cam in box that came out of the motor. The cam does great. All except for the gas mileage. It smells like fuel at idle at 13.8 to 1 fuel ratio. I have it in my lq4 85 burb with fast ez efi. It pulls hard but i could use a few more mpg due to haveing to drive it 12 miles each way to work. If it wont make a huge difference i will keep the after market cam in. Drives great on street with a 18-2000 rpm stall and 700R4 4.10 gears. In 4th with converter locked it will do 1100 rpm threw town fairly smooth. Just looking to get rid on fuel smell.
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06-02-2011, 12:30 AM
#10
Find a small cam with a wide 114 LSA to get the most, it moves the power band up but it wont hurt the carb, a tighter LSA will bring power in faster and carbs do tend to like them, but nothing a street car would notice as far as maximum performance if it is mildly used for racing.
06-02-2011, 06:24 PM
#12
I dont have a carb any more i swaped to an ez efi kit from fast. So i am not to worried about the lsa. But i need all the low end i can have due to the 6000 lbs my burb ways. I am scared to swap in the lq4 cam and loose a bunch of power and only get .5 mpg better. Is there any ignition up grades i can do to stop the smell and help mpgs?
06-02-2011, 08:13 PM
#14
I would not be concerned with a lean condition. Go ahead and lean the idle mix out even more. You should be able to have that thing idle at 14.7-15.1'ish and be just fine. The software should allow you to richen the mixture at throttle tip-in, just off of idle to prevent a lean condition upon acceleration.
06-02-2011, 08:54 PM
#15
I may play with it over the week end to see how it does. I can set the ratios at idle wot and cruse. The cruse comes in any throttle position over 0% and wot fades from cruse to wot at 50% or more in a linear fashion so at 75% it is half ways betten cruse and wot setting.
06-02-2011, 09:15 PM
#17
http://67-72chevytrucks.com/vboard/s...d.php?t=393076
06-03-2011, 01:20 PM
#18
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re Find a small cam with a wide 114 LSA to get the most, it moves the power band up but it wont hurt the carb, a tighter LSA will bring power in faster and carbs do tend to like them, but nothing a street car would notice as far as maximum performance if it is mildly used for racing.
Why do you want to go with a 5.3 now? do you feel like the 6.0 is too much or is it because you should have kept it stock or do you think its now too fast because its not stock?
06-03-2011, 04:04 PM
#19
This is no hard fast rule, but in general, when cams get above 210 degrees at .050" is where fuel economy starts to drop off. I usually ran single pattern cams in those scenarios to keep the overlap low, but you could run a dual pattern as long as the spread is not too big.
06-03-2011, 11:30 PM
#20
This is no hard fast rule, but in general, when cams get above 210 degrees at .050" is where fuel economy starts to drop off. I usually ran single pattern cams in those scenarios to keep the overlap low, but you could run a dual pattern as long as the spread is not too big.