Let's say hypothetical that somebody had a 6-71 blower that they wanted to put on their 428. They are planning on dual 600 cfm carbs, a new manifold, aircleaner and of course all the blower hardware. Would they need to forge the internals? What is the most boost he could run w/o forging the internals? How would the power of this blown 428 compare the power of a heads/cam 428? Reliability? ~TIA~

 

according to the literature I have you could safely run 5-7 pounds on standard cast or hyperutetic pistons providing the CR ratio is around 8.0:1 already. anything higher will require forged pistons. roots blown engines tend to be very sensetive. if your the type that likes fiddling under the hood all the time go with the blower. If you like the install it and forget it idea go with the heads and cam. The blower will net you more power from idle to wide open though.

 

You also have to concider that a blower setup will cost you 30%, round about, of your final power output. If you are going to install the blower you will want to run at least 10 psi or better to show some improvement over stock. Otherwise run a 50-75 shot of NOS to create the same effect. The small shot of NOS will not hurt the stock pistons.

 

Yeah I see what you mean. I also thought of running that NOS "cheater plate" that goes under your air cleaner. Would the 428 be able to handle a 100 shot?

 

No Way! Without running forged parts your engine will self-destruct if you are going to run low boost AND the NOS. You would be O.K. to run one or the other but not both combined. Most NOS Mfg's will tell you it's safe to run up to a 100-125 HP shot of NOS on a stock engine. I'm estimating your 428 with 6 Lbs. boost will be making around 500 HP and 550 ft. lbs. torque...that's getting borderline for stock parts...Deen

P.S. There is NO comparison between a blown engine (roots style blower that is) and the same engine with big cam and high flowing heads. They can end up making the same HP at higher RPM's
but the torque of a blown engine at low RPM's will turn your tires into melted strips of rubber. Once you've driven one you'll never go back to naturally aspirated again.

 

Deen is right on. Keep in mind also that 6psi of boost or 100 shot of nitrous will ruin your engine if allowed to detonate or especially if it runs lean. Nitrous is a cheap safe way to make power only when done conservatively and correctly. At low RPMs, a 100 shot of nitrous can add well over 200 ft lbs of torque. Good to keep that in mind when you push that button.

 

(quote) No Way! Without running forged parts your engine will self-destruct

i dont agree...ive been running 16#s for a year now on a 8.8c/r stock ford longblock with no trouble. they key here is your a/f ratio. keep it rich and youll be ok. of course there is a limit to what every part can mechanically take but not enough credit is being given here to non-forged parts. i can have all the forged parts in the world...but if im lean they forged dont mean nuthin...they fail just the same. lean is mean on any part regardless. maybe im doing something wrong because i havent self-destructed yet....... maybe i should add some nitrous..oh wait...ive laready done that....oh and my engine just turned 90000mi....

 

hold the phone fellas....I didn't mean NOS and blower at the same time! I meant NOS instead of blower. So what is it going to run the blower I already have on the 428? I have an idea but I want to hear what you guys say. Also, I was thinking about the carb(s) for something like this? Would you need to run dual four barrels? I do have one almost new 600 cfm now, I thought I could get another one of those and run a dual quad setup. Or, would a single be better? Okay one last thing, I was talking to a good friend of our family who rebuilds turbos, blowers and diesel engines for a living and he said when you get a 671 blower off of a engine, a lot of times you need to put bushings between the casing and the impellers because there's a space there which lowers the boost. Anybody know about that? I know I asked a mouthful, thanks for helping.

 

if talking about pulling a 6-71 off a desiel, its way cheaper to get one thats already running on a gas. If taken off a desiel the end plates have to changed (because the detroit runs and lubricates the the blower through a gear drive off the camshafts and not a belt), if taken off an in line 6 detroit the blower casing itself has to be machined because of a ridge on one side of the outside of the blower. Those bushings you talk of, even if they are good, have to be changed to plastic because on a deisel the blower just moves air and developes no boost so the bushings are made of a material(some kind of metal i believe) that will leak pressure when they develop boost and make the blower very ineffecient.

On the other hand you are talking about pulling one off a gas, Providing it has not been abused (had large debris run through it or overheated) the bushings should be the only thing that needs replacing. To check to see if they are in need of replacing check for scores on the ends of the lobes(where the bushings are located) and make sure the blower turns freely with no rough spots. It is a good idea to put masking tape where the carb bolts on(sealing this area) and slowly turn the blower. If the bushings are in good shape the masking tape should dome out when turning one way and suck in when turning the other way indicating air movement.

Depending on your knowledge of tuning carbs, probably one larger carb is better. Beleive it or not a Q-jet makes a fine carb for a mild blower application. Since the back venturies are larger than the front it helps componsate for the leaness that generally comes about from the first second of hard acceleration. This characteristic can be hard to tune in to a holley or a carter and still be able to achieve a decent fuel to air mixture when rpm increases. Also imagine trying to do this with two carbs and trying to get them to run identical to each other. Also 1200cfm would probably too much anyways. I think one carb or 2 2Barrels(if you like fiddling) would be better for a low boost application like you described.

 

Nobody was saying they wouldn't hold up to either, they were just saying both at the same time. Doesn't the lightening 351W have forged pistons? 16 psi and nitrous? You are lucky. Not a safe route to go if your pistons aren't forged even set up with the proper a/f mixture. Non forged parts can take more of a beating than most people think though like you said. I knew a guy with a bone stock 91 AOD 5.0L mustang running 22psi of boost through a supercharger. He blows a head gasket every pass he makes but has never left parts along the track. The small blocks are pretty strong but it will that guy's engine will fail sooner or later.

 

the older lightnings have hypers. i have done my share of head gaskets...its my fusible link...

 

Hey thanks guys, I think I've decided against it.....too much money and time that I don't have. I think I'll just do heads/cam. Thanks alot!