Detonation or pre-ignition?
- Thread starter Lazy JW
- Start date
My truck will keep the 300, but I have an 81 1/2 ton PICKUP that could get by with a bit less grunt if need be in order to squeeze a few more mpg out of this liquid gold. Just trying to get ideas for now, the 240 would be a long-term project, I am working on freshening up a 300 for it now but it is a minimal rebuild just to get going.
Any thoughts on the 240 w/EFI head and flattops?
Joe
Any thoughts on the 240 w/EFI head and flattops?
Joe
Ever thought of using a NP 205 transfercase behind the 4sp? Then you could put a TALL gear in the back for empty driving or highways. And you would have the 2 to 1 low range for low speed power(can you say 150HP Tractor?)
Lazy JW":p7je2yev said:
You know the swept volume is 40CI, and the chamber volume is around 68cc, so you can figure the compression yourself (my calculator is in the truck, it's cold, and I'm lazy). IIRC, it's annoyingly close to 10:1.
I don't know that the 240 would be any more economical. It takes X number of HP to go down the road, and since you're dealing with a situation where "all other things are equal", my guess is that it would be a wash...
Look at it this way: Say you want to shoot .38 special ammo as accurately and economically as possible. Which would be better, a Smith & Wesson 'K' frame in .38spl or .357 mag? We know which one has the potential for more HP & torque, should you be inclined to put your foot in it. Therein, I think, lies the practical difference.
6bangerbill
Well-known member
I think your right, the mpg would be ideally equal depending the efi tuning skills of the owner of the two engines being compared, and of course his foot mass. Some other variable other than cubic inch displacement would probably be the determining factors for mpg.
Not EFI, just carburetors for me. Of course the power required will be the same to do the same work, BUT, if one could squeeze more power out of the same amount of fuel it should help. A little, teeny bit. If we could make an engine more resistant to detonation, then we can run more compression. A long rod 240 has a theoretical advantage, and topped with an EFI fast-burn head with a tight quench we should be able to run what, maybe 20:1 compression 
:roll: . Just trying to keep ideas coming.
Joe
:roll: . Just trying to keep ideas coming.Joe
6bangerbill
Well-known member
I could never understand the reason that the 300 and 240 had such a low compression. Also why the piston crown was designed with at least a .060 or more deck clearance. Just raising the piston top for a .040 or .045 head clearance should really wake up these engines, even more for at least 9.5 compression. I guess they must have been designed to use drip gas.
A
Anonymous
Guest
Ill have to add that one year (15 years ago) my dad and I took a trip to FL. He driving a '90s Aerostar and me in my good 'ole '73 Econoline E-250 with a 240 in it following behind. We filled up at the same time each time. I actually got 22 mpg in that van with 4:11 rear end at 65 mph. He didnt even make 20 mpg with all the fancy EFI and Vee-sixed-ness. I drive a '90 1/2 ton Econoline with a 300 six and 308 rear and dont get that good of mileage.
Is there a possibility here that 240s get better gas mileage just because maybe they have 60 cubic inches less displacement... Thats kind of alot...
I mean its a big pump thats taking in more gas and air every revolution right?
Is there a possibility here that 240s get better gas mileage just because maybe they have 60 cubic inches less displacement... Thats kind of alot...
I mean its a big pump thats taking in more gas and air every revolution right?
6bangerbill
Well-known member
You would think that a van would like the 300 better unless you were tailgating or drafting. Or it could be the extra friction and piston speed also affected your gas milage.
I ran a quick comparison on my engine modeling program for both engines in racing form and found only a 23hp decrease when compared to the 300. I ran the 240 to 8000 rpm and the 300 to 7500 rpm. Friction losses were 137hp compared to 189hp for the 300. Piston speeds maxed at 4282 compared to 4942 ave ft/ min. Not bad considering the 500 rpms higher revolutions. The 240 requires a smaller intake runner and plenum.Using identical cylinderhead ports, volumetric efficiency increased about 3%.
Maybe this explaines the performance of the Ambrose 260 ci ford inline roadster that ran 7.60 et's in nhra competition in the nineties. He turns 9000 rpms and 700hp on his runs.
I ran a quick comparison on my engine modeling program for both engines in racing form and found only a 23hp decrease when compared to the 300. I ran the 240 to 8000 rpm and the 300 to 7500 rpm. Friction losses were 137hp compared to 189hp for the 300. Piston speeds maxed at 4282 compared to 4942 ave ft/ min. Not bad considering the 500 rpms higher revolutions. The 240 requires a smaller intake runner and plenum.Using identical cylinderhead ports, volumetric efficiency increased about 3%.
Maybe this explaines the performance of the Ambrose 260 ci ford inline roadster that ran 7.60 et's in nhra competition in the nineties. He turns 9000 rpms and 700hp on his runs.
A
Anonymous
Guest
with all the talk about mega strokers in hot rods and such it kinda makes you wonder if any body is making a shorter throw crank and even longer rods for the 240. an Anti-Stroker! In these days of high gas prices it would pay to try anything that might help. That seems like one heck of a program you got there 6bangerbill. What is the name of it if you dont mind me asking??
6bangerbill
Well-known member
I have several, because each program omits some important information, no one program provides enough information. The one I use the most is an old dos version of Engine Analyzer v2.5 by Performance Trends. It is so useful that Im still finding new ways to use it (especially for intake manifold construction).
THe other is Racing Systems Analysis, Engine Pro v3.1 by Patric Hale. It is unusual in that the intake cam lobe dimensions, intake manifold, and head flow are input and his program recommends the other perameters. (specific for drag racing engines only) It is the only program that I know of that plots port flow versus piston and valve position. Ever wonder at what piston position and valve lift the maximum port flow occured during the intake cycle? It even provides specific cfm flow and inches of vacuum at each valve and piston position. You can dublicate the perameters on a flow bench to match the flow requirement to each valve lift position.For example for a 240 ford max piston speed during the intake stroke occures at 77.4 deg when the intake valve is open to .568 lift. Guess at what valve lift the port should be flow tested and for max cfm? It really answers many questions we all were afraid to ask.
Another program that helps the drag racer is Performance Trends - Drag Race Analyzer. It can tell you when your cam duration is too large and you killed off torque needed to pull that big 14" drag slick. Just plug in your converter stall and engine torque curve.
No one program claimes to give all the answers, but it gives an educated place to start on an odd ball racing combination like a 240 six in a 1700# street/drag roadster.
THe other is Racing Systems Analysis, Engine Pro v3.1 by Patric Hale. It is unusual in that the intake cam lobe dimensions, intake manifold, and head flow are input and his program recommends the other perameters. (specific for drag racing engines only) It is the only program that I know of that plots port flow versus piston and valve position. Ever wonder at what piston position and valve lift the maximum port flow occured during the intake cycle? It even provides specific cfm flow and inches of vacuum at each valve and piston position. You can dublicate the perameters on a flow bench to match the flow requirement to each valve lift position.For example for a 240 ford max piston speed during the intake stroke occures at 77.4 deg when the intake valve is open to .568 lift. Guess at what valve lift the port should be flow tested and for max cfm? It really answers many questions we all were afraid to ask.
Another program that helps the drag racer is Performance Trends - Drag Race Analyzer. It can tell you when your cam duration is too large and you killed off torque needed to pull that big 14" drag slick. Just plug in your converter stall and engine torque curve.
No one program claimes to give all the answers, but it gives an educated place to start on an odd ball racing combination like a 240 six in a 1700# street/drag roadster.
