would stock heads hold up to low boost in a 400 with stock style forged pistons?

 

I couldn't swear to it, but I'd think so considering that the stock configuration was such low compression to begin with. Those crappy open chamber stock heads won't breathe for beans, tho, so I'm not sure how much of a benefit it would be to "force" them to by introducing an induction system.

If, however, you're wanting to try it to find out, my gut tells me that low boost levels like 5 to 8 lbs probably wouldn't be a problem. Heck, even if it is, the worst thing is that it'll give you an opportunity to rebuild the 400 the way you want to with better breathing heads......and THEN you could probably introduce the boost and notice a much bigger difference. The only issue would be to keep the compression low enough so a forced induction system (blower or turbo) won't burn the thing up. It'd be quite a sight to see an EFI blown 400, but that does also raise some other issues....

If it's a blower, you'd have to go with a type that capitolizes on the low end power of the 400. A twin screw type, like a Kenne Bell, produces max boost at 1800 rpm, and keeps it that way throughout the band. A centrigual supercharger wouldn't seem to be appropriate, as they build boost throughout the rpm band, which means you'd have to take the 400 to high rpms to get max boost, and that isn't where the 400 is most happy. The huge drawback is that you'd have to adapt an intake manifold to accept the Kenne Bell, while also bolting to a 400...tall order. If a GT-40 intake for a 351W can be adapted to a 400, then a Kenne Bell would bolt right up...would be an odd sight to be sure. Maybe a whipplecharger could be adapted to fit as well, by mounting as an accessory, and running the boost tube through a carb hat. Hell, I dunno...just spitballing here.

If, on the other hand, it's a turbo system, they can build boost fairly rapidly, so the boost could potentially be in the middle of the powerband on a 400, if it spools up at the right rpms. There's a company that makes some fairly trick turbo setups, and it's called Squire Turbo Systems, if I recall correctly. They did a twin turbo setup on a corvette, and mounted both turbos where the mufflers used to be. Their systems are designed so you can mount the turbo pretty much anywhere you want down the exhaust of the vehicle. The other added benefit to that is that if you mount the turbo on the far end of the vehicle, you can reduce the temperature of the air charge headed toward the intake without the absolute need of an intercooler (although it'd be nice too).

Anyway....short answer: yeah, I think a stock 400 with its low compression could withstand low amounts of boost (5 to 8 lbs).

 

yea thats about all the boost wanted to run. and wanted to do a turbo setup with an intercooler like a holset hx35 or an hx60 with just low boost. and also trying to find stock style low compresion pistons forged thinkin of checking with tim meyer or trying to get forged 351c pistons.?

 

If you were to run 2 smaller turbos, you would build boost much quicker. The smaller turbos will limit you on your output, but if you are shooting for low numbers like under 15 or so you should be fine. Running each turbo at 5 pounds would net you 10 and that is easily had by a T3/T4 or even a smaller T28. This engine seems to have low enough compression to handle some good boost, you just have to tune it right.
The only draw back to a remote mounted set up is, sounds stupid, but theft. The plus to a set up like that is you really don't have to run an intercooler.

 

In the late 70's shelby made a turbo setup for the 351M and 400 engines it bolts up to the stock engine and uses a ray-jay turbo on it. The turbo can make 10 pounds of boost with no problems. The problem is finding one of these kits, the only one I have ever seen is the one that I have. Good luck

 

i would definately not use a 1975 or later D5 head casting for a forced induction build, the exhaust port is more than somewhat challenged, you'll want the best exhaust port you can get.

it wouldn't be very hard to duplicate a RayJay style turbo kit, most custom installs in the 70's used a stock cast iron exhaust manifold(or both) with a turbo flange grafted onto it. then the opposite side manifold would connect to the turbo manifold, and the exhaust pipe comes off the turbo.



a 'Squires' type turbo install would be even easier to at home, no custom manifolds needed. Squires Turbo Systems - Turbocharged Innovation!

 

1975/78 351M & 400 cylinder heads were VERY prone to cracking.

Some were replaced under warranty with new heads, but some were not.

Some of the heads were welded, but Ford dealers did not do this (at least they were not supposed to).

Magnaflux these heads FIRST before using them!

Passenger cars used 351M's from 1975 thru 1979, 400's from 1971 thru 1979.

F Series trucks used 351M's & 400's from 1977 thru 1982.

351M/400's were also used in 1978/82 Bronco's, 1980/82 Econolines.