Rob, what material are you talking about? Is that so that the centering ring on the crank blower pulley will set inside the dampner like the stock one from Vortech?

Chas

 

The excessive forces that are applied to the crankshaft snout and balancer when spinning a supercharger (especially a centrifigul style blower) will create greater radial load on those parts than the stock ones can sometimes handle. The result is either a broken crank snout and/or a broken harmonic balancer. ATI manafucturers a larger style hub to replace the standard size piece that is much less likely to break. They are typically machined with two keyways. It is recommended that you have your crankshaft snout broached to accept a second crankshaft key. Additionally, you will need to machine the timing cover to accept a larger seal for the harmonic balancer as the diameter and therefore the actual thickness of the hub is considerably larger than the stock sized hubs.

 

Yeah, you have to have the crank pully machined to fit hub centrically into the hub. Plus I had to have about 1/4" milled down. This way the pulley will line up using the inside of the hub vice the bolts. The hub is MUCH bigger than stock, therfore the crank pulley has to be machined to accomodate. No-one told me this before hand so I had to find out the hard way.

 

In response to Boosted_Z28's post:

More or less thinking out loud here......machining for a second keyway will improve load distribution through the hub and crank. However torque on the crank snout does not change ie) torsional load that the crank will see by the blower. Assuming that failure is caused by crack propagation through either the hub or crank, I can see how multiple keys would help. If crank snout failure is caused by pure torsion then it wouldn't matter how many keys you had.

For those that may want a quality hub without machining, ASP Racing sells (or at least did) a single key, billet machined hub for ~$65 which requires no further modification to install and run. I ran this hub and was very impressed with the quality of the product.


-Scott.

 

Maybe I should have gone into a little more detail...I didn't mean for my post above to sound like I was saying that additional keyways will lesson the likelyhood of a crank snout failure. In the simplest terms, utilizing two keyways in the crank and hub will reduce the possibility of the hub "spinning" on the crank snout.

I was stating that if you purchase an ATI "big block style" balancer for the LT-1, it will come with two keyways cut in the hub (although, I believe you can special order it with only one keyway if you desire) and therefore should consider broaching your crank for the additional keyway. The biggest advantage of using this balancer is the fact you are reducing the possibility of cracking the hub due to its increased size. Sorry, I should have been more specific.

 

Hey no problem, I guess my point was that if anyone reading is concerned with hub failure, or wants to upgrade from a stock non-keyed hub to a stronger single keyed piece, that ASP might be a good choice. The BB hub kind of seems like an expensive solution if we're talking typical street/track car.

Regards,
Scott.

 

I have the T-trim Vortech also. I use an Ebay bypass valve and had to seal it up better than it came, but it passes a lot of air without going to that giant one they sell at Vortech and mounts in the same place the plastic Bosch one did.

I still have the stock hub (keyed), modified stock damper, and a very good quality crankshaft. Sometimes I wish I had gone the BB hub route, but it does look like an expensive mod.

I made sure I didn't get a timing gear with a bunch of keyways in it and I debured and radiused every sharp edge where those parts go together. I also use a good quality coated main bearing. Other than that, I didn't do anything special.

I'm not making a comment on how others have done their cars, this is just what I did and it works well for me.

 

Is it just me or is everybody making a big deal over dual keyed cranks when the Vortech head unit uses a single 1/8" key? I understand where the key slot makes the LT1 hub weak, but dual keying a BB hub just seems to be an overkill considering what the head unit uses.

Chas

 

Back to one of your original questions about the maf location, I too had t trim on my 383 with the sensor located by the air filter. I never had any tunning issues but i'm now installing a D1 and am considering mounting on the pressure side to see how that works. As for intercoolers make sure you dont cut any corners, I sold my T trim to a friend who installed a fmic and could only get #8 but after he removed the intercooler and used the stock vortech piping he instantly jumped to #16.

 

one more bit of advice. The stock kit has a tube from the suck side to the valve cover to pull off crankcase pressure. This setup tends to suck oil and if you dont mount a trap of some sort and you put the maf on the pressure side you will probably get oil all over the electrodes which could affect the performance of you car.