Discussion in 'Builds and Fabricators Forum' started by Lifesgoodhere, Aug 22, 2009.
yearly check for slip.......................
Happy Thanksgiving....dyno slip?
Probably next year....
you guys are unrelenting
He's still trying to use Microsoft paint to make that dyno slip.
Happy thanksgiving .......dyno slip?
So I to am building a Hot Rod 134 but mine is an L.
.035" shaved head
.004" decked block.
By my math I have 7.2+ compression ratio (which will run on about 78 octane fuel with lots of timing LOL) about +6hp
All NOS or new Valve train all hard seats Including a Later 134L WILLYS NOS cam +0hp
everything from the crank pulley to the clutch pressure plate has been computer spin balanced +3-4hp
Modified Peirce aluminum intake manifold designed for a Weber DGV 32/36 progressive 2 bbl fresh air intake system +3-4hp
Custom built Header into a 2.25" exhaust with a Dynomax turbo muffler +3-4hp
Vac Advance Distributor with Petronix ignitor and MSD 6A spark box. Accel wires and super coil +2hp
electric fan +4-5hp
Holley electric fuel pump +2-3 hp
if my match is correct between the increase in compression ratio the improved intake system and exhaust system as well as the removal of parasitic drag (fan and fuel pump) I should see an increase in draw bar BHP of about 25 -30 HP. I'm using conservative numbers Hoping it surprises me. I went to college for auto tech so I have done this type of modification before (my wifes 67 200L6 mustang now gets 26mpg commuting on country roads and has done 31 on long freeway trips Stock they got 19.5)
My project should be on the road about late fall this year. You can start asking for a Dyno slip about early NOV 2017
You got it!!!!
Should be able to easily make 60 HP on a dyno.
I assume your talking about a chassis dyno. It requires approx. 20 Bhp to operate the stock drive train so 60 at the draw bar would be 80 at the flywheel.
I'm pretty sure I can see numbers closer to 65-70 at the draw bar. But like I said you can ask to see the slip in about a Year.
interesting thread that evaporated?
nice, clean fhead though.
id pay money for mine to look like that!
Curious as to how you get the 2-3 hp difference between electric and mechanical fuel pumps. Standard knowledge? I'd never heard of it.
The only way an electric fuel pump will save power is if it only runs on demand. For the same amount of work, it's going to cost more to convert fuel to electricity then use the electricity to pump fuel rather than to convert fuel directly to pumping more fuel.
From what I understand, it's not the power being consumed, but the frictional drag on the cam that the pump arm is creating. Similar concept to traditional vs. roller rockers.
This is how I'd have seen it. You should see the size of the military fuel/vaccum pump on my fhead on the A1. The spring is pretty stiff and I marvel at the integrity of the camshaft lobe that it rides on. I could see some parasitic loss, but 2-3 hp seems on the high side.
Golly... you would think that the engineers in 1950 could have designed a low-friction fuel pump, if it was actually responsible for a 2-3 hp loss. 3 hp is 5% of the peak output of the L134. Do you really need the power of a lawn mower engine to run the fuel pump? At most, it's maybe 5 gal/hour an at 3-5 psi. I'd think you could achieve that with a slot car engine.
Also, the pump is riding on a film of oil on the cam eccentric, which will be significantly lower friction than metal-to-metal contact. The problem with a metal-to-metal bearing should be obvious.
This has been a good read... Lol. I think if it was that easy to make a bunch of horsepower with an F head, more people would be doing that instead of swapping for V6 and V8s...
Try moving the pump arm 2000 times a min and see how much energy it takes. You can turn a drive shaft and rear wheels with your hand but just try doing it even 600 times a min and see how much energy it uses. Now try 3000 times a min.
Yeah - but it seems that you are assuming a 100% duty cycle at full flow rates, but it is actually far, far, less than that. Using your model the pump would empty the fuel tank in seconds.
The pump doesn't take a stroke from the cam until it needs it. By design, the back pressure is holding the pump arm floating more or less in neutral, and the diaphragm spring is storing the necessary pressure/energy until the fuel is consumed. In real life it is just taking tiny hits off the cam to keep the spring pressure "topped up."
Out of those 3000 revs you cite, I'd bet it's actually "using" less than one of them. Far far less, in fact. Figure out how much fuel one full pump stroke provides - then calculate your engine's fuel consumption per minute. That's that's actual energy loss. (= tiny.)
Plus - Think about the resistance of a fuel pump spring - it's way less than just one intake or exhaust valve, and they are working full time, unlike the pump.
I think Timgr is right.
I would bet that the average alternator drag for an electric fuel pump may actually exceed the mechanical. Putting on an electrical pump may actually cost you HP just as some electric fans do.
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