Is there a way to do it? Maybe by changing drive gears or something? If that made it produce too much boost up top, could a bleeder valve be installed to vent the excess boost? Do some brands build boost more quickly than others? Thanks.

 

buy an ATI supercharger....F series. The F1 is the same size as the D1SC and is what you are looking for. It has a 5.0:1 step-up gear ratio

this will get you what you want

 

If you use a high internal gear ratio, or pulley the supercharger faster, it will come into boost earlier in the rpm range, but the peak boost will go up accordingly. For instance, if you want 6 psi boost at 2500 rpm, you'll get over 14 psi at 6000 rpm.

Curved inlet vanes will help a centrifugal start building boost earlier. The Vortech S and T trim's have this. The ATI P600B does not. I'm not sure about the other models and brands.

Mike

 

The simpliest way is to change pulley size. I recommend starting with the crank pulley. My Vortech S Trim came with a 6" crank pulley; by changing to a 7" crank pulley you will reach boost at a lower RPM and increase belt surface area to help prevent belt slippage. You can also reduce the size of the pulley on the blower unit to "spin up" your blower sooner. Blowers are only designed with a max impeller speed so you'll need to size your pulleys to the meax engine RPM you plan to run. Vortech has an impeller speed calculation on theitr website. Remember that the belt size will need to be changed to match your new pulley combo.

Pulleying up will also raise your intake temperatures...you'll probably want to look into an aftercooler to prevent pre-ignition.

 

Thanks for the answers. Now I'm just wondering if I can install a blowoff valve on a centrifugal. That way I could get the boost down low and not run too much boost before I rebuild the engine. I'll probably do that after the rings start to go or I spin a bearing or (insert various "bad things" here.) Then I'll make it into a forged 383 with heads and a blower cam. One step at a time, though.
With the higher boost setup and the bleeder valve (or blowoff valve?) I'd still be seeing high intake temps. How can I install an aftercooler without breaking the bank? I could install a used one from a different app, couldn't I? What should I watch out for if I try to do that?
Would it be cheaper (at least initially) to run a water/methanol setup? I could conceivably run smaller injectors and make up for the lack of fuel with the methanol. That might allow me to get better mileage off boost.

 

This has been discussed before and been agreed on that the added boost down low is not worth the heat you will get up top to only achieve 6-8 PSI .. Let's say you get 6-8 PSI at 2000 RPMs or something like that, and you want to keep it there all the way to 5500, that's all fine and good, you can do that, but, the supercharger is going to be spinning like crazy, will be heating up the air and you will end up getting a hotter intake charge than normal with 6-8 PSI. The supercharger won't be even close to working efficiently..

If I were you, I would just pulley for the total you want and deal with the lower end 'lower' boost levels .. I don't think you will be disappointed..

--Sean

 

Adding a small shot of nitrous to your system is a way to gain power at lower RPMs (I wouldn't fire it below 3K) and keep the air cool. With a window switch you can even shut the nitrous off early if you're worried about too much power on the top end (if the engine's not built to take it). Rich Krause is probably the expert on this setup.

 

gasnmyveins, I think you need to slow down a little. First, tackle the challenge of installing a supercharger and making it work properly. It may be harder than you think. Then find ways to improve the set-up. You may be jumping too far ahead with too little supercharger experience.

You can't and shouldn't try to compensate for a lack of fuel using methanol.

This wouldn't help your gas mileage off the boost anyway. I'm using 42 lb/hr injectors (stock is 24 lb/hr) and my gas mileage hasn't changed. When you change the injector constant in the computer, it cuts the pulse width and runs the same at idle and part throttle. Also, an FMU only increases fuel pressure under boost, not part throttle.

Mike

 

My s-trim will make 7lbs but only at wot. anything under 3500 I barely see any boost. My gauge is new so I assume its correct. I always wondered if their was a way to make that 7lbs at least long enough to see it!!! You guys running more boost, when does it start to come on??? Does anyone run the methanol ??Thanks