Now, I'm not a newb at these. and maybe this is best reserved to ask EngineDoctor, Lakesonly, and Obnoxios001 directly, but I thought the question relevant enough that the masses opinion may be valuable.

I recently sold this cat a great deal on a Teflon Stripped 8-71 blower and shipped it to him in Australia. It wasn't a cheapo Weiand, Dyers, BDS or Blower Shop unit either, a real Kuhl unit and fresh. This is going in a weekend drag car and week day/off-season cruiser that will be used OFTEN.

Anyway, he's in the middle of a 540" or so Chebbie build and wants to do this right. He asked me what I thought about rods, pistons, rings choices etc and that is a lot opinion based, y'all can throw what you think, his "mates" are telling him all billet, but my advice was this. Tell me if I'm wrong.

"Forged pistons are a must, and quality, cleaned and beburred paramount for your build. There is some question as to whether forged  factory or similar rods or billet I or H-beams are the order of the day because we do not know the pressures of boost involved, OD ratios, etc, let alone the quality of Aussie Hi-Test gasolines. My personal opinion is this. QUALITY forged I-Beam rods will out perform and out last the best of the best of "billet" I-Beam or H-beam rods on a year to year, mile for mile, cruiser/weekend racer build. ANY Forged steel crankshaft will outperform and out last ANY custom billet crankshaft. End of story, always, no one has proven me wrong yet.

Again, my personal opinion is that while the billet stuff, in Drag racing or other, and is replaced after every run, MAY be physically stronger (I seriously doubt that, just CHEAPER to make more of them), but replacing those in those circles is nothing, and WEAR is a matter they never even remotely see, whereas for you and me? A HUGE deal! I don't beleive, never have, that a billet crank or rods needs to be involved in any Street or Marine application. Nor does aluminum. Racing? those guys have almost unlmited budgets and yes, on paper and a 2 million dollar Rockwell Hardness machine their stuff MAY be "Stronger", but not "Harder" to take wear and tear. Meaning they can throw more HP at it for shorter periods, then replace everything and do it again next weekend. We, the "normal people" cannot, and will not do that." 

Ray   

If it were my motor, I would go a good forged bottom end, with forged h beams and a solid forged blower piston with total seal rings. I agree that if it will see road use, the billet and fancy light weight parts have no place on the car. Also would not run a Teflon insert blower on a street car either but to each his own. My dad has a Kuhl supercharger and it is most definately a better unit than a weiand and the like. Again my .02


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Good info! and actuallly one that was never asked! Yes, the teflon is not going to last more than a few thousand miles in a street application! I did recommend having those replaced with Nylatron, eithe now or when they need it though.

Good eye!   

Ray

tried a blower on one of my mustangs with hyper pistons and a stock bottom end.  ended up breaking a piston skirt which cracked the cylinder, water went in and then it blew a rod out the side. entire motor was pretty much toast. 

forged everything with boost or nitrous.  do it right.

If it were my motor, I would go a good forged bottom end, with forged h beams and a solid forged blower piston with total seal rings. I agree that if it will see road use, the billet and fancy light weight parts have no place on the car. Also would not run a Teflon insert blower on a street car either but to each his own. My dad has a Kuhl supercharger and it is most definately a better unit than a weiand and the like. Again my .02

Sounds like sound advice, but lemme ask this.  How long does teflon coating last in a frying pan that is beat to dath with forks/spatulas/spooons, whetever..........

Ray

You bring up a good point. With the frying pan analogy. The only thing is, the frying pan Isn't trying to tear its self apart the whole time it is in use. (centrifugal force) I know the tolerances are tight and it shouldn't matter but it does. The harder the motor is spun the more cf is being put on those Teflon inserts, they will wear against the case and eventually wear out. 


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Which is worse to wear out tho? Teflon/Nitro inserts or the aluminum itself off from the rotors if they were NOT so equpped?..............

Gotcha guys huh?

Which is worse to wear out tho? Teflon/Nitro inserts or the aluminum itself off from the rotors if they were NOT so equpped?..............

Gotcha guys huh?

The aluminum should never come in contact with another rotor. You put a .006 feeler between them to set em up

When cold set-up, yes, under use? Tdawg, you know as well as I do they rub up against each other in heated use like Lindsay Lohan and Drew Berrymore on a dance floor at a Grunge club...........

Ray

Come on Ray...Drew is old enough to be Lindsay's mom... ewww   

How did G.M.C. get a half a million miles out of them, on the street? Maybe they didn't have the amount of boost?

Daniel

What the things originally did on the 2 stroke diesels was a different matter, really. Wasn't "boost", per se, they simply pushed air into the cylinder and exhaust out and not driven as hard or fast. They also had their case oil shared and pumped around with the engine oil, so more consistent cooling, and the obvious leaks that allowed oil into the rotors no matter what you did. The engines do run forever and are still the choice for backup power plants, etc. because of the amount of power in a smaller package. Hence the "positive displacement" acronym associated with them.   

When some nut back in the 50' or something thought it was a brilliant idea to steal one of these things and strap it onto a Flathead Ford or early Hemi (Not sure what was the first blown Hot Rod built) they realized a few things had to be fixed. First is adding additional pins to secure the rotors to their shafts and using high speed bearings because of the RPM's involved in gasoline street blowers.

Ray

And boy...did them old Detroits "bleed". Oil...everywhere. Inside, outside,'n everywhere in between