Yep, what he said. I mis-conveyed my thoughts. I didn't mean to say just take the ratios from another car. What I meant to say/type is what you so eloquently did. Figure the whole CFM ( as well as boost ) per RPM thing. Basically the rpm of the SC. I was just saying that you could get a baseline from other setups.

 

Speaking of exhausts (Dr O's post)... Bob, what are you running now? I recall you last having Webb's, but your sig doesn't seem to mention it.

 

I just started reading this thread this morning but must admit that I was thinking that the whole time. I'll be like spiderX, give them my car if they work on it Twincharged 62... wow. That would be awesome. If anyone wants to try take my car. I can just run to work.

 

bolding done by me...

Wouldn't there be more volume at the desired pressure since the M62 is a larger blower?

For example, let's say M45's make a certain amount of boost, lets say 13 psi, with X amount of cfm. If we were to put an M62 directly in and put a pulley on it to run the same 13 psi, wouldn't there be the same amount of pressure among the air, just more of it (which happens to be cooler too)?

I'm not very familiar with superchargers, but with turbos you can have a little turbo spinning out at 20 psi and barely move any air, whereas you can have a massive turbo thats spinning at a measly 10 psi (which is most likely going to be out of its efficiency range) and it'll still move much more air and make more power.

So if we had a super massive blower, that was running only 13 psi, would it put out the same volume of air as an M45, only at cooler temps?

 

No, to get the same boost, you have to spin the M62 slower. To use your example, to get the same X CFM out of the M62 at 13 PSI of boost, you'd turn it about the rpms of the M45 divided by 1.3 (the ratios of SCs), or whatever the exact number is....This has to do with the efficiency map of the turbo and where you run it (in terms of boost vs airflow), the whole idea behind the M62 is that it's more efficient than the M45, so you benefit by cooler air, and hence more power potential.Yep, that's pretty much it, give or take little bits...

Matt

 

Unfortunately, the M62 is only slightly more efficient than the M45. The Eaton website shows that for a given output, the M62 requires about 10% less shaft hp than the M45. I don't understand how saving a couple hp on the SC is going to add 50 whp.

 

I'll tell it like it is.... the original WMS exhaust that I posted all the video on was killer except is was too damn loud.....I waited for months for the re-do and what they came up with was a mess...... the resonator was taken out and the muffler rattled and had all kinds of wierd resonances... I keot it on my car about an hour and took it off...... at this point Randy got disgusted with the whole vendor relationship and brought it "in house" and that is the last I heard.... I currently run a Milltek which I like very much.....

 

Thanks Bob. It appears that you have a full Militek system: head, cat, and back. Just trying to better visualize the flow potential for the M62 on your car... A good weekend to everyone!

 

Have a great weekend as well......

 

and now I'm baffled... So, for the M45

10 psi boost flows ~210 cfm @ 10,000 RPM with a temp rise of ~145 deg F and requires 15 hp to drive...

The M62?

10 psi boost flows ~205 @ 8000 RPM with a temp rise of ~180 deg F and requires 15 hp to drive.....

This would make the 62 worse at this flow and boost.....

So I looked a little deeper...

For the M45

10 psi boost flows 305 cfm @ 14,000 RPM with a temp rise of 180 F and taking 25 HP to drive.

The M62?
10 PSI boost flows 305 cfm @ 10,000 RPM with a temp rise of 180 F and takes 22 hp.
So now the M62 is slightly better.

Now let's look at one last one..... But backwards....

For the M 62
10 PSI boost flows 450 CFM @ 14,000 RMP with a temp rise of 195 F and takes 35 HP to drive.

For the M45 (I have to estimate, the graphs don't go that high)
10 PSI boost needs almost 20,000 RPMs to flow the 450 CFM, and comes with a temp rise of 200-250 F and takes 45-50 HP to drive.

So what's the lesson here? The M62 is more efficient at higher flows. But at lower flows the M45 is more in the sweet spot. But for sure, the M62 to do what an M45 with a small reduction pulley can do without paying the heat price the smaller blower pays. The temp rise curve for the 62 is actually a higher number than the 45 at low RPMs, but it's essentially flat up to and beyond the SC red-line. That's why it's a winner....

Matt

 

Hi Matt....the 62 car feels no no car I have been in with a 45.....

 

Matt, I was sort of under the hope or expectation from what's been shared that the M62 would help with low-end performance, torque. It seems from what your guesstimating, that might not be so? It seems that there are some unknowns or missing data to deduce accurately... and we'll just need to wait for some results.

 

one of the things I learned was that the right pulley ratio to get "equivalent" performance to the M45 is RPM and boost level dependant, it's not just a simple scaler.

Also, that this mod is really about higher end airflow, as the 62 can reach flow numbers that would have the 45 creating so much heat that it would melt down into a puddle of aluminum.

Matt

 

Whut? Sorry but I need interpretation on this one. Most I'm pretty good at reading between the lines.

 

The most impressive thing about the 62 car is the low end......maybe my car has no low end due to the exhaust/header/head/cam

 

such that it gives you more down low.... I just wonder how much boost up top one will end up with....

And people shouldn't get all wigged out... The tables don't have any numbers where we like to run, which is well over 10 lbs of boost, it's possible that the higher levels would move the relative efficiency numbers around some, I just can't tell because there isn't enough data to see the trends vs boost.

But it is possible that you set it up to be 10% stronger at 3000 RPMs, that it will be much more than 10% stronger at 7000 RPMs. Now, that wouldn't be so bad, would it?

Also, the real world is very different (sometimes) than data extrapolation from insufficient graphs... So I'll love to see how this all compares to the real system when it's all finished.

But it does mean there is a way to figure out the smallest pulley you'd want to run, figure out the airflow you want at red-line, and size from that. Build one as see how much boost increase there is at low RPMs.

But also, this reinforces the what is, at least in hindsight, obvious: you want all parts of the system sized in a complimentary mannor. If you have a stock motor, it's better to keep the M45 than and underdriven 62 (at least at the same power levels) because they are better matched. Actually, this may not be really true, it seems the MCS is right on the outer limit of what you can do with a 45....

But I'm sure you'd all agree that one of those big huge blowers that goes on top of a dragster probably won't be the best for our cars.....

But this also means the 62 is a better match as the engine HP climbes above what the stock car offers, for a certain range of hp, then it too will be spinning too fast for the air-flow! Just what these HP limits are, I have no real clue! I just know they are there.....

Matt

 

I think he was saying that the 62 feels like no car he's been in that has the stock 45 blower.

But then didn't that 62 you drove Bob have something like 23 lbs of boost? If so, that might explain it!

 

TonyB - Thanks!

Matt - And I thought Bob was good at doing the balancing act. Pffft! You just showed a whole new level at that skill.

 

I have been up very late the last two nights and I'm very tired and not very sharp...... the 62 feels a lot stronger a than a 45 car..... it accelerates in 6th gear very nicely..... from say 3K cruising.......which my car also does very nicely but it has a lot of other mods.....I am decidedly off balance but still standing and I have a date tonight

 

here is a way to look at it:
the 62 is the same as a 45 but with longer rotors; if you spin it too fast, it will heat the air just like a 45. the reason you spin the 45 faster is to get more air output (cfm). with the 62, you can get the higher cfm at lower rpm without whipping up the air.

so if you put a pulley on the 62 that spins the rotors at the same rpm as the 15% on a 45, you will get the same heat, but a lot more air.

now dumping more cfm into the restriction of the intake manifold, et, al, will necessarily create more boost pressure, but the charge temp will still be rpm related

 

Bob, get some rest... take a nap. I'd hate to see you fall asleep tonight and get taken advantage of .

Thanks John for some clarity! So, with what you know, what would you speculate as to potential power that we can probably expect? It would seem that we have enough info to draw some conclusions for a ballpark range at least...

 

Thanks Tony, now I got enzyte commercials with "Bob" being "up all night".

 

You know how the 19% and above underdrive combos get knocked for the high RPM heat? Using the M62 creates a system with the flow benefits low down of high underdrives, but doesn't pay the heat penalty at the top....


that's the part that everyone will like!

But there's no free lunch, and like that initial run that got 23 lbs at 5000 RPM showed, something that's bearable at 3000 RPM may not be at 6000! This is a perfect example of setting up the system with too much benefit down low for the system to handle up high! But I bet it felt good at first!

A little more digression into the SCs....

Here's the performace graphs of the 62 4th generation (actually the MP 62 because it had the VE graph).... (such as they are).

Look at the volumetric efficiency. That shows that as rpms climb, you get closer and closer to delivering the actual volume of the SC per revolution. An easy way to think of this is that as the rotors spin faster, there is less time for the air to leak back in the small gaps between the rotor and the housing..... Anyway, that gets better the faster it spins......
Now look at the temp deltas.... it rises slowly, but it does rise. Over all SC efficiency will be something like the VE curve divided by the temp delta curve (not exactly, but conceptually you get the idea.....)

Now lets look at the 45..

While the VE isn't shown, the shape is the same. But look at the temp curves. This is where the action is. At high RPMs, the VE curve is pretty much flat, but the temp curve for the 45 is starting to rise, and quickly at that.

Now the fact that the 45 starts falling off at due to temp performance at high RPM while the 62s temp performance is still pretty much constant, is why the 62/45 benefit ratio will increase with RPM....

Matt

 

No doubt, the M62 is preferred over the M45 when flowrates way outside the M45 design are needed. I suppose this should have been obvious, although Matt's analysis is nice to see. So let's say what the M62 brings to the party is the greater pumping ability. Unfortunately, the stock engine can't swallow that much air, so the pressure goes up. I think I read 20 psi in an earlier post. At that delta P, the M62 thermal efficiency will likely be quite a bit worse than at the 10 psi delta P Matt used in the high flow calculation. So, in reality would the M62 be an efficient high flow pump for the MINI? I still have my doubts, although I'll be the first to admit I'm no SC expert.

 

indicates some benefit can be had! Just how much is what's interesting. And this should be a screamer with a ported head.....

Matt