DIY PROMDo It Yourself PROM chip burning help. No PROM begging. No PROMs for sale. No commercial exchange. Not a referral service.
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Have you guys any experience or links regarding calculating rough idea of fuel economy of a engine combination, by knowing roughly the dyno graph (engine), gearing and vehicle weight?
Re: Calculate fuel economy of engine before running..
Hit the road...
Soooo many factors involved.
If you had a full map of the engine characteristics (torque vs MAP & RPM, and record the fuel flow or pulse width at each MAP & RPM point - to get BSFC contour map), you could at least compare it to another engine in the same vehicle setup. But that takes a bit of time on an engine dyno. You could also punch in some estimated drag on a mustang chassis dyno, and go to cruise speed, and record the engine fuel consumption, or even run a drive cycle with some fuel flow data. Better data is found on the road though.
You can generalize some things (like x improves economy, and y hurts it), and hope to know which way the balance works out compared to the original case. For example, compression helps, EFI (fuel and spark) tuned 100% helps, cubes hurt, gears hurt, fat tires hurt, tall tires help, overlap might hurt, headers and loud exhaust help, heavy foot hurts, hood scoop hurts aero, lowered car helps aero...
__________________ -Jeremy- EFI Calibration Engineer, Director of R&D, Software Designer, System Department Manager (Fuel Injection Technologies - dianpen.com) - Living in China since Nov '04!!!
86 Z28 - rusty, tired, needs to be put to sleep - 89 GTA 5.7L needs new paint and the parts on the shelf installed, 79 Malibu Classic with '91 L98, 4L60, 3.73
Re: Calculate fuel economy of engine before running..
Quote:
Originally Posted by RednGold86Z
Hit the road...
Soooo many factors involved.
If you had a full map of the engine characteristics (torque vs MAP & RPM, and record the fuel flow or pulse width at each MAP & RPM point - to get BSFC contour map), you could at least compare it to another engine in the same vehicle setup. But that takes a bit of time on an engine dyno. You could also punch in some estimated drag on a mustang chassis dyno, and go to cruise speed, and record the engine fuel consumption, or even run a drive cycle with some fuel flow data. Better data is found on the road though.
You can generalize some things (like x improves economy, and y hurts it), and hope to know which way the balance works out compared to the original case. For example, compression helps, EFI (fuel and spark) tuned 100% helps, cubes hurt, gears hurt, fat tires hurt, tall tires help, overlap might hurt, headers and loud exhaust help, heavy foot hurts, hood scoop hurts aero, lowered car helps aero...
I see what you mean!
I was kinda pondering what my vette might get for fuel economy with the 358, blower, and 6 speed vs my truck. My truck gets around 14mph highway, 10 city.
While my camshaft in the vette has a little overlap, the car only weighs like 2800lbs, is very aerodynamic and has a 6 speed transmission. Maybe I'm mistaken, but the blower HELPS fuel economy under a light throttle cruise, doesn't it?
I know if I went WOT light to light it would get about 7mpg, but I'm curious how it would be over the highway.
I've only driven the car twice with the new combo before the snow hit so I have no idea how much fuel it uses.
Re: Calculate fuel economy of engine before running..
Quote:
Originally Posted by anesthes
Maybe I'm mistaken, but the blower HELPS fuel economy under a light throttle cruise, doesn't it?
-- Joe
No, pretty much can't help. It's a source of friction/drag. When not open throttle, the RPM of the blower is the same (closed or open throttle). The blow off valve should be set to be opened if there's some manifold vacuum though, so it won't be making pressure, but it's still spinning (belt and gear friction) and moving air (doing some work).
Re: Calculate fuel economy of engine before running..
Quote:
Originally Posted by RednGold86Z
No, pretty much can't help. It's a source of friction/drag. When not open throttle, the RPM of the blower is the same (closed or open throttle). The blow off valve should be set to be opened if there's some manifold vacuum though, so it won't be making pressure, but it's still spinning (belt and gear friction) and moving air (doing some work).
Hrmm..
I wonder if it at least would be better than my truck
I wonder if I could get the MPG display to work with my '730 ECM using the $58 code..
Re: Calculate fuel economy of engine before running..
ScannerPro has the math functionality to display it although its just a calculated value.
Seemed pretty close to what I actually get.
I put my foot down too much to relize the average that it indicates.
See the S_AUJP V4 definition I made for SP.
It is modeled after the one Magnus put in the $6E definition.
Keep in mind this uses the PW from the ECM but the PW at the injectors has some hardware compensation for voltage applied.
