[Katech_Zach]

Bigger is not always better. The larger, heavier rotors have more drag/loss when spinning them. Maybe it makes 2-3 more lbs of boost but sucks up 50 more hp spinning it, which cancels out... The 2650 is very good, and very efficient. It is very hard to beat.

[EDFHOBBIES]

Originally Posted by Katech_Zach

Bigger is not always better. The larger, heavier rotors have more drag/loss when spinning them. Maybe it makes 2-3 more lbs of boost but sucks up 50 more hp spinning it, which cancels out... The 2650 is very good, and very efficient. It is very hard to beat.

If that's the case they need to start making carbon fiber rotors or hollow titanium rotors that take less effort to spin maybe even ceramic bearings.

Is the 3100 gonna have port injection or use the spacers?

[Puddin]

Originally Posted by EDFHOBBIES

If that's the case they need to start making carbon fiber rotors or hollow titanium rotors that take less effort to spin maybe even ceramic bearings.

Is the 3100 gonna have port injection or use the spacers?

There won't be a 3100.

[radz28]

Originally Posted by EDFHOBBIES

If that's the case they need to start making carbon fiber rotors or hollow titanium rotors that take less effort to spin maybe even ceramic bearings.

Is the 3100 gonna have port injection or use the spacers?

Magnuson had a video where it seemed like they were farting around with a 4100-or-something rotorset and either the rotors or the housing was a composite or something. It was interesting.

[toohighpsi]

The 2650 is a great blower because it is pretty much perfectly sized for a 6-7L engine that runs up to about 7500 RPM.

Since SC power consumption is measured at steady state on a test stand the rotor weight doesn't have any impact on this number, but the actual increase in weight between a 2650 and 3100 is probably quite small (I think the rotor was 6mm longer and 4mm bigger in diameter.

The problem with a bigger displacement SC on these size engines is the fact that you end up spinning it slower. The thermal efficiency of these PD superchargers is highly dependent on the ability to create "dynamic seals" between the two rotors and the housing. There is an optimum speed for the best sealing at a given pressure ratio and flow.

Spin it too fast sealing get better, but the air handling gets worse - it becomes increasingly difficult to fill the control volume between the lobes and then exhaust the air in a short time which decreases thermal efficiency and increases power consumption (example - a 1740 on a 416 trying to make 25+ psi boost).

Spin it too slow, the air handling is good, but the internal leakage at high pressure ratio (high boost) will increase - causing lower thermal efficiency. This is quite easy to think about, if the air from the control volume (space between the lobes) is forced around the outside of the lobe into the previous volume, it essentially needs to be pumped twice. That of course is going to consume more power and create more heat.

So maybe a 2650 is pretty ideal for most the street race applications out there up to 7500 RPM, the 3100 of the same rotor design would probably be too big and spin too slow for the desired pressure ratio.

Now put that 3100 on a 7L that spins 8500+, the blower speed goes up, pressure ratio decreases and things are happy again.

Now I've really simplified this, we would generally build fairly complex models to understand the air handling inside the SC - which then need to be verified with testing. Sorry for the rambling, but hopefully this helps to explain the reasons bigger is better, up to a point...

As for the 4100 - it was a quick unit we pulled together creatively named after the date of it's conception - APRIL 1st.

[Joshinator99]

Originally Posted by toohighpsi

The 2650 is a great blower because it is pretty much perfectly sized for a 6-7L engine that runs up to about 7500 RPM.

Since SC power consumption is measured at steady state on a test stand the rotor weight doesn't have any impact on this number, but the actual increase in weight between a 2650 and 3100 is probably quite small (I think the rotor was 6mm longer and 4mm bigger in diameter.

The problem with a bigger displacement SC on these size engines is the fact that you end up spinning it slower. The thermal efficiency of these PD superchargers is highly dependent on the ability to create "dynamic seals" between the two rotors and the housing. There is an optimum speed for the best sealing at a given pressure ratio and flow.

Spin it too fast sealing get better, but the air handling gets worse - it becomes increasingly difficult to fill the control volume between the lobes and then exhaust the air in a short time which decreases thermal efficiency and increases power consumption (example - a 1740 on a 416 trying to make 25+ psi boost).

Spin it too slow, the air handling is good, but the internal leakage at high pressure ratio (high boost) will increase - causing lower thermal efficiency. This is quite easy to think about, if the air from the control volume (space between the lobes) is forced around the outside of the lobe into the previous volume, it essentially needs to be pumped twice. That of course is going to consume more power and create more heat.

So maybe a 2650 is pretty ideal for most the street race applications out there up to 7500 RPM, the 3100 of the same rotor design would probably be too big and spin too slow for the desired pressure ratio.

Now put that 3100 on a 7L that spins 8500+, the blower speed goes up, pressure ratio decreases and things are happy again.

Now I've really simplified this, we would generally build fairly complex models to understand the air handling inside the SC - which then need to be verified with testing. Sorry for the rambling, but hopefully this helps to explain the reasons bigger is better, up to a point...

As for the 4100 - it was a quick unit we pulled together creatively named after the date of it's conception - APRIL 1st.

Great info Mike, thanks for sharing.

LOL at the 4100…!

[cjperformance]

Originally Posted by toohighpsi

The 2650 is a great blower because it is pretty much perfectly sized for a 6-7L engine that runs up to about 7500 RPM.

Since SC power consumption is measured at steady state on a test stand the rotor weight doesn't have any impact on this number, but the actual increase in weight between a 2650 and 3100 is probably quite small (I think the rotor was 6mm longer and 4mm bigger in diameter.

The problem with a bigger displacement SC on these size engines is the fact that you end up spinning it slower. The thermal efficiency of these PD superchargers is highly dependent on the ability to create "dynamic seals" between the two rotors and the housing. There is an optimum speed for the best sealing at a given pressure ratio and flow.

Spin it too fast sealing get better, but the air handling gets worse - it becomes increasingly difficult to fill the control volume between the lobes and then exhaust the air in a short time which decreases thermal efficiency and increases power consumption (example - a 1740 on a 416 trying to make 25+ psi boost).

Spin it too slow, the air handling is good, but the internal leakage at high pressure ratio (high boost) will increase - causing lower thermal efficiency. This is quite easy to think about, if the air from the control volume (space between the lobes) is forced around the outside of the lobe into the previous volume, it essentially needs to be pumped twice. That of course is going to consume more power and create more heat.

So maybe a 2650 is pretty ideal for most the street race applications out there up to 7500 RPM, the 3100 of the same rotor design would probably be too big and spin too slow for the desired pressure ratio.

Now put that 3100 on a 7L that spins 8500+, the blower speed goes up, pressure ratio decreases and things are happy again.

Now I've really simplified this, we would generally build fairly complex models to understand the air handling inside the SC - which then need to be verified with testing. Sorry for the rambling, but hopefully this helps to explain the reasons bigger is better, up to a point...

As for the 4100 - it was a quick unit we pulled together creatively named after the date of it's conception - APRIL 1st.

I love the technical explanations, even if simplified. Its what im here to learn.

[radz28]

Thanks for all the info. I didn't know about that April Fool's 4100, lol. I recall VMP abandoning 3100. Oh well. Too big for me anyways.

[laynlo15]

Well we know the 2650 can now make some big power, Jason's Vengeance Zl1 made 1405 rwhp on about 28 lbs of boost with Mike's new tensioner and Port Injection, Jason had been getting lots of belt slippage and the new tensioner cured that. Unfortunately, he cracked a cylinder wall on the stock Lt4 block at the Caddy Attack. He's going all in with a new LME sleeved block getting ready for Tx2k in April. Hold on for some 7 second passes, hopefully.