I would say an HH would be OK with extensive bowl work and detailing and a properly set up shoe and loader. Once the hull moves five feet, I would call the HH issues moot.

Then again, may just be me.

We got to play with a custom high lift impeller years ago, all I remember is the bowl pressures were higher at lower RPM and fell off at speed (I read into that to be severe cavitation). The HH impellers increase the torque demand in the middle, (read; more bite).

I am still not sold on the idea of High Helix impellers. Seems to be some majorly contradicting results floating around out there.

Load it, straighten it and control the restriction on the nozzle, that is where the science is. JMHO

Make sure the impeller is enhanced for the given RPM and that the bowl reflects the same enhancements and it negates anything an HH can do..... Hope I didn't strike a nerve.

GT

I would say an HH would be OK with extensive bowl work and detailing and a properly set up shoe and loader. Once the hull moves five feet, I would call the HH issues moot.

Then again, may just be me.

We got to play with a custom high lift impeller years ago, all I remember is the bowl pressures were higher at lower RPM and fell off at speed (I read into that to be severe cavitation). The HH impellers increase the torque demand in the middle, (read; more bite).

I am still not sold on the idea of High Helix impellers. Seems to be some majorly contradicting results floating around out there.

Load it, straighten it and control the restriction on the nozzle, that is where the science is. JMHO

Make sure the impeller is enhanced for the given RPM and that the bowl reflects the same enhancements and it negates anything an HH can do..... Hope I didn't strike a nerve.

GT

1000 HP on a AB will be spooky.... 

As for Blowers, you definitely don't need to go HH, unless of course my injected on alcohol comment got you to thinking... 

I have a friend that did some time with BDS, at that time, hard anodizing and billet rotors were all the rage... Things have not changed much in the GM huffer world...

How many RPM are thinking you will need to run? I can tell you that everything will run out of steam above 6,200...

GT

Which heads are you thinking?  Im not sure you will see an increase in HP from just the head change.  You might even lose HP if you don't step up the overdrive.  Just going to a larger head with no other changes will cause a drop in boost as it is a greater volume to fill.  Aluminum heads lose a lot of combustion chamber heat.  There is also some debate that the boost will drop with better flowing heads.  There is also a rigidity factor that is preventing me from switching to aluminium.  My engine with iron heads rarely changes lash settings compared to my friend's engine with aluminum heads.  I am really curious of your outcome.  I have never had the opportunity to run multiple sets of heads on the same engine.

I have a friend who worked at Pfaff Racing Engines when a customer ordered two blower engines and told them to design the whole program.  The decision to build one with their standard head (for the application) and one with an aggressive (LARGE) port size was made.  The engine with the large heads was down on power and responsiveness.

Hmmmm, how much do you want for your Merlins?

12.3% overdriven?

Big on bottom = 14:1 over

Little on bottom =12.3:1 under....

GT

First off, what motor? The same 468? An 8-71 turning 14% over I would think would make way more than 8PSI, closer to double that.... Then again, I could be FOS.

It is my personal opinion that the blower should be spun as slow as possible while giving you the boost you desire.

The efficiency drops like a turd into an outhouse when you get much higher than 25%, I would call that a point at which a larger blower is needed.

I dunno, probably every case is different, but something sounds funny.... To me anyway....


GT

With a non stripped set up, the efficiency takes a poo earlier.... I still think that somehow you are short on pressure..

Any idea what camshaft?


GT

Having your blower tightened up will make a huge difference.  Without strips, you have clearance between the rotors and housing which translates into a lot of leakage.  Contact Littlefield, Mooningham, Hampton, or your favorite "race" blower shop and have them clearance it for gasoline.  Mert Littlefield has always treated me very well and since his passing, Littlefield Blowers still treats me very good, even though I am a nobody.

I'm willing to bet that you will have a whole new animal on your hands.

Totally agree.

Literally the only people I have ever dealt with when it came to blowers was Blower Drive Service (BDS) in Whittier. That being said, I have never heard anything but good coming from Littlefield.

I would be willing to bet your current blower is pretty tired and ready for some help. According to my calculations, even without teflon, you should be well into the 12 PSI range at 6,000 RPM. If Clay Smith did your camshaft, I would doubt seriously that there is a whole bunch of unnecessary lift on the intake side. So unless you have puny carburetors, I would say I think I know where some of your budget needs to go.

GT

Totally agree.

Literally the only people I have ever dealt with when it came to blowers was Blower Drive Service (BDS) in Whittier. That being said, I have never heard anything but good coming from Littlefield.

I would be willing to bet your current blower is pretty tired and ready for some help. According to my calculations, even without teflon, you should be well into the 12 PSI range at 6,000 RPM. If Clay Smith did your camshaft, I would doubt seriously that there is a whole bunch of unnecessary lift on the intake side. So unless you have puny carburetors, I would say I think I know where some of your budget needs to go.

GT