Soooo.... I'm toying with the idea of picking up an 8-71 blower kit for a 440...

I have two options to set it upon:

1968 440 HP Magnum that's currently in my Challenger;

1973 motorhome 440 with a steel crank;

I'd probably put it on the later due to likelyhood of having a lower compression ratio and if/when I scatter it there won't be anything desirable lost.

I plan on changing the cam to something wilder, maybe doing a mild port on a set of 906s but leave it otherwise stock.

I am just building a grenade by leaving the stock pistons and bottom end in it? The car already has a decent CD ignition system and headers/exhaust.

Thoughts?

Depends entirely on you. Tuneup and supercharger drive ratio will determine how long the engine lasts.
I'd use the '73 engine, 7.2:1 stock compression and all.
The heads on that engine, if they're not the industrial heads with exhaust manifold bolts not in a straight line, will be 213s. They'll have an induction hardened valve seat for at least the exhaust valve, I sort of remember my 213s having the heat rings around both seats after hot-tanking. They may or may not use "peanut" plugs, mine used a regular 3/8" reach gasketed seat plug, some have the tapered seat 5/8" socket plug.
There's nothing magic about 906s. I'd spend the time bowl porting the 213s. I'd use a cam with around 240 degrees at 50 lift.
An 8-71 on a 440 you will want maybe a 1:1 drive ratio or less to avoid overboosting. Make sure you start out with a super rich mixture and 32 degrees total advance at 3000 rpm.

If you keep manifold pressure below 5psi gauge I don't think yor bottom end will grenade. And as far as a '73 block or forged crank, nothing wrong with it at all, it's not a throwaway. I don't know where you got that idea.
R.

Use the 73, I think it will work very well.

Sheldon

The motorhome piston tops are a lot thicker than the same year passenger car and light duty pistons are, good for supercharging put two carbs on it to make it look tuff You can make 600 HP easy on pump gas, 700 is doable also if your careful

Thanks guys! That's precisely what I was hoping to hear!

i hope you would put some new arp rod bolts in!the TQ you can get from the blower will make an awsome engine.

Keep in mind that the blower drive ratio affects the outcome.

and do yourself a favor and buy the blower setup from "the blower shop", best product and customer service in my opinion.

ARP main studs also.Blower motors are hard on bearings.For the cost its cheap onsurance.Rocky

agree with folks on here, go with the latter engine. your percentage of drive will determine how long things will last. keep it conservative, you won't have to do much at all to it as it sits. get it up there, you will scatter something. as far as cam, if you change it, wide lobe sep, like 114 degrees works best. you could run the stocker and be fine in all honesty. i am running a 6-71 gmc, 10% underdriven, it's giving me 6lbs of boost, and more torque than you will know what to do with. i have had great luck with running edelbrock carbs, the afb's are pretty cheap, and tune easily. a pair of 600's or 750's would be fine. my two cents, living with a blower car driven at every chance given......