Blower Question

[Chiefmike]

I'm doing a frame-off 67 swb. I bought a ZZ4 350 a while back but now I'm wanting to add a blower/supercharger. I'm not really looking for the added power, but more for the look and sound...I just want it for the "Wow".

The first question is, can I do it with this 10:1 compression motor by changing the cam and backing down the boost with a pulley change? Anything else that would make this work for just a weekend show cruiser?

The second question....does anyone know if this can be done (with the low profile 144) and it all fit under the stock hood?

[jocko]

this won't answer your questions - however, if you're looking for the sound and not the power, a Pete Jackson (or equivalent) gear drive to replace the timing chain will mimic the sound of a blower and easily fit under the hood leaving everyone to wonder... "what's he runnin under that hood???"

10:1 is normally too high for a blown motor. For street use, 8.5-9.0:1 is more in the ball park. You pose a great question though, boost reduction and cam changes. If you're more in it for the wow than the go, then perhaps the gear drive is a viable option.

All I can say is that I grew up driving past Van Senus Auto Parts on Kennedy Avenue in East Chicago - and every single day, a two-tone white and yellow 55 bel air went screaming by and I could have SWORN it had a blower stuffed under the hood somehow. Until one day I stopped at the shop and asked him - it was a mild 327 with gear drive. So, a little later, when I was hot rodding an old 57, I included PJ Gear Drive for the "sound" and had two holleys for the wow. It was fun. Good luck, I'm interested in other folks more direct answers to your good questions.

[hugger6933]

the 144 will fit under your hood with the small block.I have a blower on my shelf at the shop that use to be on a buddies 68 GMC.he gave it to me after he screwed up the intake and saw the prices of replacements. I had another friend who bought one of the very first zz motors and put it in a pro street truck with like 18.50 mickys and quickly blew it up. It had a combo of too much boost and too much compression[ I feel]but he has a 6-71 type blower on his. I feel if you could pull the heads and add a thick head gasket to lower the cr down some to say 8:75 to 1 you could make it live with the underhood blower.Just make sure till you get it adjusted out right err on the side on fat side of things yes it robs power but it saves motors as well. Jim

[TBONE1964]

It is possible but not recommended. You ideally want to keep your static compression below 9:0:1.

I would contact BDS or Weiand tech support and ask the people that know. Cam selection is critical, not for lift as much as duration. You ideally want a longer valve opening on the exhaust side. One thing to consider is your exhaust primary tube size if you are running headers. You have to be ale to exhaust the additional air coming into the engine.

The 144 style roots blowers are a perfect upgrade for a stock engine with low compression. Also keep in mind that to much boost will blow stock head gaskets.

Here is a chart that should help you as far as compression vs boost.

Hope this helps

[Chiefmike]

Thanks for the good info guys. Looks like I need to decide to use the ZZ4 regularly aspirated or buy another engine for the blower.

[davepl]

I ran 8psi into my 1994 LT1 forever without a problem. Until a bug in the MS-DOS version of the old FAST software gave me 255 degrees of advance. But until then it was great.

That motor was 10.4:1, so even higher. But I'd definitely (a) keep it to 6psi or less and (b) retard timing under boost (I used an MSD BTM but there are probably more modern solutions).

That, however, was centrifugal, which has better adiabatic (sp?) efficiency.

Remember the Roots is just a big air mover. A 6-71 sweeps 426 cubic inches of air every rotation, so you can underdrive it to not even make boost if you just want the look. Heck, you could probably underdrive it so much you had vacuum at WOT. Back in the 80s when fake Pro Street was cool some people didn't even run rotors (I hated that era).