Ford 240 inline six supercharge build.

Toyboytoh

Active member
Hello. New to the forum.
I own a 1980 f100 with a 240. Decided to superchargee it with the typical Eaton m90. I got the adapter all made up to sit on the intake. Now working on the pully system. I just have some questions about pressure relief and backfire valve in the intake manifold as its a draw through system. Also any tips at all would be really great. I would add pictures because I have lots but I don't know how to post them from my phone.
 
Open plenum offy C series and the Eaton adapter are on the truck. I'm curious about where to get vacum from to open the blow off valve attached to the supercharger. Also how many pounds of boost this engine can handle while still being reliable.
I also have hedman long tube headers. And I'm using a holy 500cfm two barrel carburetor for the draw through.
Q:How much boost should I run
Q:where to get vacum for the bov
Q: can I have an aftermarket bov to the intake manifold instead.
Q:how much should I advance the timing so I don't get backfire and blow off the supercharger.
Q: should I disconnect vacum advances an run just mechanical advance?
Q: will I have to use 91 octane now.
Q: how much fuel pressure should I run on my electric pump.
Q: aftermarket spark plugs?

If anyone can give me at least some answers it would really really help me. I'm so close to being done this but everything has come to a halt because of these unawnsered question. I have the pully system all pre fabed but need to know how much boost I can put on the engine before I go further. I've made this setup so I can unbolt the supercharger and everything to run N/A in ten minutes. I've also been on other forums and no one has responded to me.
 
If you have a draw through system where the carb is before the supercharger then you don't need a blow off valve.
There is no spike in pressure when the carb is closed suddenly.

The valve attached to the supercharger is a bypass valve used to bypass the supercharger during no boost cruise conditions

Unless you have an intercooler, limit the boost to 8 psi.

The ignition timing partially depends on the compression ratio of the engine and also the cam profile if you are going to use an aftermarket cam. (recommended)

You can use the vacuum advance but it must tie into the intake manifold, not the carb.

Yes on the 91 octane fuel. You may also want to include alcohol/water injection like the Snow Performance system.
Alcohol/water injection would also allow higher boost.

On a draw through system the carb is supplied with normal fuel pressure. Just be sure the supply volume is sufficient to keep the bowl filled.

With 8 lbs of boost the M90 will be drawing less than 400 cfm so a 500 cfm carb should fine.

What year is your 240 engine?
Are the engine internal parts stock including stock cam?
What blower drive ratio are you planning on using?
 
I had to remove "pictures" from the front of the link to get to your pictures.

Why 4 holes in the plate under the supercharger?
I'm thinking it would be better as an open square that matches the intake manifold opening.

Since the 1980 truck did not come with a 240, what year 240 is it?
Are pistons and cam stock?
 
I don't know what year it is. I do know this. That engine is reving out Max at 6100 rpm since I did a test with a new aem rpm gauge. Which is kinda strange to me. Brings me to believe it is has an aftermarket cam.
The holes in the plate were there to maybe help fuel mixture but I decided to go with a full square bore and canceled that idea with the holes.
 
It sure seems like it has a larger cam which will work well with the supercharger.
The larger cam increases the engines Volumetric efficiency which lowers boost for a given drive ratio.
You can start with a 2:1 drive ratio and see what boost you end up with.

At 6000 engine rpm puts the blower at 12,000 rpm which is near it's limit.
It is past the limit of the 500 cfm carb.
You may want to limit the engine to 5000 rpm when running the blower and 500 cfm carb.

Can you take the time to see what a compression tester shows for cylinder cranking pressure?
 
Already decided to go Max 5600 rpm and use some pullys to make 8.8 pounds of boost at 5600.So I figured if we use a 5" v belt pulley and a 3.8" ribbed pulley (same as SC pulley) we should get 9700rpm SC with 5600rpm crank pulley.
As for testing the compression on each cylinder I can't do that right now. I'm working but I will get you numbers soon. ( next couple of days at the max )
 
I'm showing a 6.5" crank pulley with a 3.8 SC pulley to get 9600 rpm at 5600 engine rpm
 
Assuming no head porting and a much larger than stock cam with 8 lbs of boost without intercooling or alky/water injection.

At the flywheel:
Just over 200 hp, maybe 225 between 4000-4500 rpm.
325 ft lbs of torque between 3000 and 3500
 
Well, that sounds pretty peppy to me.
Thank you. And I am looking at poring and polinsh in the future. But I've heard I can use some Chevy pistons in the 240 and was wondering if you knew the right pistons to order along with they're valves. Apparently Chevrolet valves aswell. In the next 3 - 4 months I'd be doing this kind of work to the motor.
 
From 1965-1968 the 240 piston pin diameter is .912" and the connecting rod doesn't have the oil spit hole in the big end which makes it a stronger rod than the later models.
After 1968 the pin diameter went to .975"

The Chevy piston pin diameter is .927" which means you either bore out the early rod small ends or bush the later rods to fit.
If you are looking for forged pistons then it is easier to cross reference to Ford V8 pistons or have custom pistons made.
Most of the Small Block Ford V8 pistons have a .912" diameter pin.
 
Ya the whole system is being moved from the crank to a bracket I made on the alternator then to a cylinder on bearing moving it back 4 inches to reach the superchargers snout, because the stock snout doesn't even make it past my intake manifold. It's kinda strange but I have it figured out. The picture in the link I provided are being updated almost daily with the build if you're interested in what's going on.
 
What type of pulley are you using on the balancer?

I had to have one custom machined for my S/C and I am running mine off of the existing serpentine belt, but went to an 8 rib setup.
 
80-img_20160121_071205_01_f021faa8842795a379879e5329e6eed6978f0f90.jpg
 
Back
Top