Hey people, question for those running a Raptor V with standard 6.5psi pulley.. At what rpm does boost start coming on? Mines off for repair and I want to drive around NA and need to know what rpm I can safely rev to without fouling the plugs. Cheers!

Damon, revolutions per minute shall be determined by the quality of the bearings. If you know the maximum speed of the bearings are installed, then you can calculate the size of the pulley.

I'd say being a belt driven supercharger boost would be almost instant even if its a very low psi reading

I read somewhere they hit positive pressure somewhere around 2000rpm. Able to just unplug the piggyback?

I'm talking about the rotation of the impeller. As far as I know the Raptor V develops 56000 rpm. It is important how many will stand the bearings of the impeller.

I really wish I put a plug on the standard and piggyback wires... Would have made life so much easier! Stuff redoing it now though. I should be right just shifting at 2k.. Even if the injection is mapped for 1-2psi, it shouldn't be rich enough to foul my plugs.

Stayer, I'm not too sure of details of the Raptor, even if we knew the bearing speed, we would still need to know the pulley size to calculate it properly wouldn't we?

Yes you are right. But the formula of calculation is very simple. Multiply the engine speed for the gear ratio the pulleys. Next, multiply the resulting value of the reduction ratio within the gearing Raptor V. You will get the value of revolutions. The next step is to get the maximum speed of the bearings. And calculate the size of the new pulley. For Example. The standard size of the motor pulley 6.5 inch. Supercharger pulley 3 inches (I don't know the real size). The gear ratio 2.17, 6500 rpm x 2.17= 14105 rpm Reduction ratio within the gearing Raptor V - 3.05. 14105 x 3.05= 43020 rpm. Now we need to find out the speed of the bearings. Further to calculate and obtain the size of the pulley.

You understand the course of my ideas? If for example the impeller installed bearings SKF and they will stand 75000 rpm, the 75000 : 43020 = 1.75 You can safely install the pulley 1.75 inch to the input of the compressor. If you can find the bearing size, the speed of looking for a directory.

His supercharger is taken off, and he doesn't know what RPM his aftermarket ECU is set to inject the extra fuel that the engine would use when on boost.
He wants to drive his car for a few days while the supercharger is off, if it is possible unter a certain engine speed without running too rich.

I found indications of the actuator Raptor here they are http://www.928motorsports.com/parts/raptorsuperchargers.php Pulley at the entrance 3.5" 19000 rpm. That is, your engine rpm 6500. 19000 : 6500 = 2.9 inches You can safely install the pulley 2.9 inches. However, if you know bearings, then looked directory you will know the speed which you can develop. Then make recalculation and to find out the size of the pulley.

Sorry I think you may misunderstand slightly, I am not looking to put a pulley on, I am wanting to know when the standard pulley begins to produce positive boost

So I'm just an asshole. Now I understand you. Positive boost must be from 1600 -1700 rpm engine.

Hah that's all good mate, I appreciate the help!

It's more convenient to several high pressure. Further controlled using blow off valve. That is, up to 1600 -1700 rpm BOV open and pressure is not created. Further speed increases and the valve should be closed, the pressure is positive.

Does this prevent negative pressure while the turbine is spinning too slowly to produce positive pressure?

I cant remember if it was the ECU's that Tim was selling with the superchargers or it was someone else
But there was a blanking plug that you go buy if you ever wanted to remove the aftermarket ECU for some reason and leaving the wiring there
Maybe contact Tim from raptor and see what he says, would be your best bet

Does this prevent negative pressure while the turbine is spinning too slowly to produce positive pressure?

Like a blow-off valve in upside down, venting atmosphere pressure into the intake vacuum?
A reverse blow off valve? Suck off valve? :S

Until the open blow off valve in the intake manifold of negative pressure. That is, the lower atmospheric pressure. And no matter how quickly rotates a turbine. As soon as the blow off valve closes, the pressure becomes positive. That is above the atmospheric pressure.

Thread mine!!!

apart from raptor is there another place I can get a smaller pulley from (boost increase), I can remember someone saying that the eaton pulley (supercharged v6 commondoe) was the same