^^^No problem, will get your build sorted...

Not 100% sure this is going to happen, but the supercharger lays in the efi valve cover notch like it was made for the 300. Pulley alignment is really close there also. The custom adapter that would have to be made to connect the 4.9 lower intake manifold and Kenne Bell v8 plenum would be rather simple.


The best combo in my opinion is a supercharger with a large turbo feeding it. Instant tq that also makes the engine act bigger to spool a large, less restrictive turbo. Neither power adder will have to work very hard, keeping charge temps down. Similar to a compound turbo setup, but has the advantage of not having to push air through a small turbo in the upper rpm range.

 

 

 

That is a very cool set up. It does look like the valve cover was designed for it. That thing would be a beast with just the Kenne Bell, let alone a big turbo added to that! How big of a restriction does the blower become when also running a big turbo? I've seen it done on the old 6-71 & 8-71 blowers but never a newer style twin screw set up. The only down side to the way you've got that set up would be, the valve cover removal. It would be an even bigger pain then the stock efi upper.

I've wanted to build a blown 300 using the more budget friendly Eaton M112 or H122 for a long time. They aren't as efficient as the KB's but are really cheap compared to a new KB. I wanted to mount the blower on a fabricated bracket on the driver side of the engine and run it thru a intercooler feeding a couple blow thru carbs. But multiple people kept telling me it wouldn't work because the blowers needed a throttle body on the inlets.I didn't see what the issue would be. A BOV is pretty easy to add if the stock recirculation valve isn't enough.

 

Jmerchant6_9: The KB1.5 is the smallest and should support 350-400 crank hp max on a 302. Air flow is air flow but 302's have a short stroke and tend to keep revving and make hp much easier than a 300. The tq will be incredible on a 300 though.

fordman75: The blower will always be less of a restriction than motor alone, as long as the blower by itself is big enough to provide boost to the engine to red line. Then as the turbo builds boost, it helps the blower increase airflow and pressure.

If the blower produces 8psi, and the turbo another 8psi, then the blower pushes 16psi into the engine while only doing the work of the original 8psi. Neither power adder is working very hard, keeping charge temps down. Charge temps from each power adder will of course be compounded as well as psi, but temps will be much lower than pushing a blower hard by itself.

As for the "remote blower/supercharger" set up you want to run, yes, a simple blow off valve that opens with engine vacuum will work great. Can also vent it to the inlet side of the blower for a closed or recirculating system.

Even though centrifugal superchargers don't do much at low rpm, slamming the the throttle shut at 6000rpm and 20psi has the same effect. There is not an inlet side valve, it relies on a blow off valve to vent the boost/air.

 

Thanks for that info. That's good to know.

The turbo & blower set up would open up a lot of options on my tow rig build. That could give big block or possibly even diesel kind of torque #'s out of a 300. And that could do some wicked things in my 54 F100 project on the 240.


I couldn't see that causing a problem. But I thought I would double check with someone that is smarter then me on this subject.

I'll keep watching the progress on your project and see how it turns out.

 

What combination of lower end parts would be OK for 16+ lbs of boost?

 

.032" top ring end gaps, the rest stock with a proper tune.

 

No steel crank/rods? cast pistons? I know (or have heard) steel cranks were in big truck and industrial engines; I've never personally seen one. For rods, I "think" there were no Ford offerings, but know there are aftermarket options especially if rod journals are ground to Cheby size. Of course, plenty of forged piston options if you do the math with the compression height, pin size vs rod, etc, and adapt.

I've never had a forced induction engine and read all kinds of things of what's needed, but like this thread as it's practical and real example of doing it for our big sixes, so hopefully my Qs are tolerated. My '81 would be perfect for this kind of build.

 

The steel cranks came in the HD 300's that came in the big trucks from 65-early to mid 70's. You may find one in certain industrial engines but it's fairly rare. They were mainly in the early HD engines. But the cast crank is plenty strong. It's a beefy crank and is supported by 7 main bearings. I've never sen anyone break a cast 240 or 300 crank. If they did I bet they were turning close to 7,000 rpm.

All 240 & 300 rods were forged rods. They never came with cast rods like some of the small 6's did ( 200 & 250's ) . The early rods ( 65-67 ) , both 240 & 300, are stronger then the later rods. The early rods don't have the oil squirt holes and they have the SBF V8 sized small ends .912" piston pin diameter. The later rods will have the squirt holes and a .975" piston pin diameter. Under very hard ( racing ) use the oil squirters can develop stress risers ( cracks ) . If you are rebuilding a big 6 I would recommend having some ARP rod bolts installed. And you can also have them balanced, polished and shot peened. And that will handle just about anything you'd throw at it unless you are planning some high rpm racing. Then a custom set of aftermarket rods would be the way to go.

The pistons and rod bolts are the weak links in the short block. With boost you need to open up the ring end gaps like Sick6 said. If you don't it doesn't matter what kind of pistons you run they will break. The stock cast pistons were known for cracking skirts, except the 95 &96's which had hypereutectic pistons. If your tune is right, just about any piston will handle boost. But when the tune is off then you start getting into burnt/broken pistons. Hypers or forged pistons just give you a little added insurance. But as Sick6's build is the proof. If done right the cast pistons can survive boost.

 

Great info, thanks Fordman.

 

Excellent post fordman75, thank you.

Well, we have been trying to figure out what everyone is going to do project wise in our community, and some deals have been made.

Riley will be sticking with the twin turbo 351w tangerine Mustang as his only project to keep it nice, and sold the sleeper.

Riley's dad will be getting the supercharger from post 363. He was going to turbo his 5.0 foxbody, but having an AOD and nice exhaust already, the supercharger makes far more sense as a near bolt on deal, and will save him a ton of money vs the labor and needed hardware to go turbo such as stall converter, turbo back exhaust, etc....

Jim, a boss of mine from many years ago, bought the 300 engine from post 363, and I will be turboing it and installing it in a '84 corvette next year. We sat down and talked about doing something wild with a 300 in a Pinto or Maverick. I told him that the only car with a long enough engine bay to fit the 300 decent is a corvette. He said "I have one!"'

I bought the sleeper. I just still want a truck and miss the fun ton. It will get a twin turbo big block and take on a different look. Once a person has a taste of a turbo big block, it's HARD not to crave it.

The 38 will be my final act down the road. Have accumulated an inline six with early rods, hyper pistons, np435, and explorer 8.8. I want this inline to really shine with low resistance drive train behind it, in a lightweight vehicle (under 3000lbs. with me in it) vs a heavy, poor aerodynamic truck with power robbing drive train. A new, undisclosed at this time, turbo cam is in the works.

 

Picked up a 96 efi 460 for the sleeper, just thought I would do a test fit in the 38 for fun before taking the engine to the trailer for winter storage. It will fit without the clutch fan, but too many things are tighter than I like.