A few years ago Hot Rod magazine published an engine build story trying to see if it could build a 500-horsepower motor from scratch for five thousand dollars. So of course, it started with a Chevy small block and was successful. But that’s kind of like trying to predict whether a kid is going to prefer candy or broccoli–too easy.

As a sort of follow-up, the magazine allowed me to take up the same 500-for-$5,000 challenge with a bit of a twist. Instead of going for the safe bet, I started with a 400 Ford. The idea was that since nobody gives the old 400 any respect, you can find a block and crankshaft dirt cheap. That gives you more cubes for less money compared to a SBC, and hopefully a leg up right out of the gate.

I got this one out of a junked F100 pickup for free, but for the magazine we started with a figure of $125. The secret weapon in this build was a pair of aluminum Edelbrock Performer RPM 351C heads. An update on Ford’s great Cleveland heads, Edelbrock’s Performers feature signifcantly improved chambers and ports over the stock heads, besides being about half the weight than the origianl cast-iron pigs. Edelbrock also makes a dual-plane intake for this block and head combination, and that was used as well.

But from there things got more difficult. That’s because the 351M and 400 engine family enjoys almost zero aftermarket support. I partnered with KT Engine Development for the build, and we did a lot of head scratching to find parts on the cheap that would help us hit the horsepower goal. We ended up going with a set of K1 connecting rods with a 6.300 inch length for a big block Chevy and matched them with eight KB hypereutectic pistons for a 340 Dodge because the compression distance was what we were looking for. Custom slugs would have been much preferrable, but we couldn’t afford them under our five-grand budget.

Because the 400 rarely gets any love from performance enthusiasts and because we built it with a variety of parts for different makes, we ended up naming this engine “The Mutt,” and the subsequent article that ran in Hot Rod was headlined the same. We ended up getting an OK 504 horsepower out of it, but what was really impressive was the incredibly flat torque curve that started out at 560 lb/ft at 3,800 rpm and didn’t drop below 500 until 5,400 rpm. Peak torque clocked in at a whopping 565 lb/ft. But we did, however, exceed our five-grand budget by a few hundred–and that’s not counting the new valve covers you see in the photos.

Below is a short video of the dyno session at KT Engine development when we were finishing up this motor. It sounds great and has never been seen before, so I thought I’d include it here. I believe the dual-plane intake was great for torque but really choked off the air flow beyond about 5,500 rpm. One of my regrets with this build is we didn’t have the time or money to try a single plane intake, which I think would have produced a big jump in peak horsepower.

This engine is still sitting in a corner of my shop, and I’ve been pondering using those fantastic heads on a Windsor block for a future build. It probably won’t have this engine’s 431 cubic inches of displacement, but with the right selection of parts it should come close to matching the horsepower numbers, if not the torque. And a Windsor won’t have the same bellhousing and engine bay fitment problems the primarily truck-based 400 will have when trying to squeeze it into a car. So what do you think? How should we build out our upcoming Windsor and Cleveland mix? (Clevor in Fordspeak.) Let us know in the comments, or the forums, and we’ll try to work ‘em into the build. 

If you’re interested, you can check out the original Hot Rod article here.

Here’s the dyno sheet showing the Kansas-flat torque curve:

And here are more photos from the original build: