Real Street Performance

XR7 Dave

Registered User
It has been repeatedly brought up that certain blower applications are better than others for street performance, so I thought it might be of interest to compare two different blowers in similar applications and how they help the 3.8L SC motor make useable street power.

I specifically cut off both of these charts above 5200rpm for 2 reasons. 1) street performance is below 5200rpm 99% of the time, and 2) both applications were having issues with either belt slip or insufficient injector above that rpm.

Both charts are available in full if someone so desires but that is not the topic of discussion here in this thread.

The cars used for this comparison are both excellent runners and easy 12 second cars. Both engines exhibit decent street manners and could be considered daily drivers. Both motors have some "trick" parts with neither one having a significant advantage in terms of cylinder head flow or camshaft profile.

In the first case an MPII at 15% OD was used for one run and an MPIII with 20% OD used on the second pull. Some adjustment was made to compensate for an overly rich condition as you can see from the AF chart. Further adjustment of AFR and timing did not result in any more power so the final number could be considered an optimized tune for comparison purposes.

As the chart shows this netted a gain of 7.9rwhp (2.3%) and 18.5rwtq (4.7%).

In the second case an off the shelf Magnusen S-Port was used with 5% OD on the first pull and a total of 10% OD on the second one. No adjustments were made between pulls.

Net result was a gain of 5.7rwhp (1.7%) and 15.8rwtq (4.1%).

This means that with the MPIII conversion the motor had lost about 51% of the gain in torque it had netted earlier in the rpm range, and the S-Port had lost about 58.5% of it's torque increase by 5200rpm.

Discuss.
 

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Nevermind i'm retarded. They seem to be relatively close together. Is almost 10rwhp worth it to switch MPIII, well I just dont know.

What motor combo is that on?
 
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So, does this mean that switching to an MPIII from and MPII gains only 10 to 15 rwhp at 5200 rpm? And that is spinning it at 20%??
 
but isnt this on motors that already have all the horsepower squeezed out of them? But lets say on a lil bit above stock motor? I am pretty sure you can see a big gain from an MPII to an MPIII? Right?
 
WoW! thats alot closer than expected.

I was surprised to see the s-port actualy beating the MPIII up to around 4,500. It looks like there is not a significant advantage for the MPII or MPII over the s-port till you get around 5000 rpm, after that it looks like the s-port is starting to really run out of steam. Above 5,000 it apears the MPII and III have a much shallower fall off and more potential if you have the motor and the injector to handle it.

Unfortunatly these are on different motors so its not a perfect comparison but still a very interesting comparison. How much boost was produce for each example given?
 
When someone has the time/money to do so it would be nice to see the MPI MP II DaveAR and S port on a non slipping belt setup. On both a stock and heavily modified motor. Dan Slys blower should be thrown in tehmix as well to see what one can do with a modified stock blower.

I dont see this however happening as a lot of money and time would be involved in getting it all done legit. But who knows
 
Being that this was done on two different cars we cannot come to the conclusion that these facts are 100% correct. We must remember that each car responds different to modification. I will be conducting a similar test this summer swapping my MPIII for a stock 94-95 Blower and dyno the difference. :) With that being said I can believe what I am seeing. I'm sure there is reason for this too.

What I would really like to see is the ultimate M90 blower shoot out. ESM, S-Port, MP, MP II, MP III. But it wont happen. :D
 
I posted this to hopefully initiate some discussion on the effects of blower changes and OD ratio on the performance of the motor in the rpm ranges likely to be seen most often on the street. The S-Port blower and MPIII represent the opposite ends of the spectrum when it comes to porting an M90 which is why I chose to use them. The difference in the power curve from an MPII and MPIII might be hard to see, but it should be much easier to see the difference in how an S-port performs vs. latest MPIII.

With all the enthusiasm and resulting controversy over the MPIII, I thought perhaps it would be good to look at the real world results of overdriving your blower and what it means to you on the street.

All too often people focus on peak HP numbers without paying close attention to the area under the curve. As Charles pointed out in another thread, useable HP and peak HP are two different things. I thought there were some interesting things about those graphs other than peak numbers that people might want to talk about.
 
Ok so now I get to sound real dumb again. Wouldnt the better option for the street be a blower that made power without having to overdrive it to much or am I missing something. Move the most amount of air to a point I guess. Is there a diminishing return after a certain amount of overdrive.Say at 15% you get 15 pounds at 20% what would you get? Is the extra boost worth the parasitic loss? It would seem there has to be a point of diminishing returns. Or am I missing something?:eek:
 
Has anyone put a MPIII on a STOCK motor and tested for power increases? I know that modded cars have done it, but I am curious about a stock motor with stock cam, heads, IC and all that jazz.
 
We need a bench test comparison

....this may be unrealistic but I would really like to see a comparrison of all our sc options on a bench. I dont know how a manufacturer goes about testing their models, but it would be interesting to know.

There are too many hidden variables that we just cant see on a dyno. For example, seeing comparisons of drive power loses for a given rpm and pressure ratio, outlet temps., and loses to belt tension would be ideal. In the real world though, testing all the blowers on the same car with as much data logging info as possible (inlet/outlet temps, boost pressures ect.) would get us closer.

Those graphs are a reminder to me about the compromise we have to make with supercharging. Regardless of which blower/pulley combination we chose there will be a certain range that it is most effective. I think there may be potential to extend that range but that is a topic of another thread.

QUOTE=XR7 Dave] The S-Port blower and MPIII represent the opposite ends of the spectrum when it comes to porting an M90 which is why I chose to use them. QUOTE]

When you say opposite ends of the spectrom do you mean how exteme they are ported, or the aproach they took with the porting?
 
I agree that all of these blowers need to be dynoed on ONE car. SC's vary too much in order to determine the differences in the outcomes of the blowers accurately.

Swade, the S-Port is a mildly ported m90 as opposed to the MPIII being the highest end of porting as far as m90's go.
 
In regards to the blower porting. The S-port is a very mild porting job. It is the standard port match done by Magnusen and repeatable by anyone with a couple hours and a dremel or die grinder and it fits the stock 94 plenum.

On the other hand the MPIII represents the epitome of M90 porting technology. It has been upgraded in every way possible to take advantage of everything we have learned about these blowers over the past 15 years. The case has been cut and modified and it requires a special inlet.

I figured if there was a real world difference to be seen, then these two blowers would make it obvious.

If the club really wants comprehensive testing done all they have to do is pony up the cash for the dyno and ship the blowers to one location where a suitable vehicle and witnesses are available for testing. However, that was not the intent of this post.


I was asking people to discuss the dyno charts in question.



What do you notice about the first chart? Well first of all you see a linear gain from the MPII to MPIII all the way from the initiation of the test to about 4800rpm. Average gain is about 20rwtq until (we assume) belt slip starts to eat into the power gains. How much of that gain is due entirely to the additional 5% OD? That is the question I was hoping to answer by posting the chart of another test done without changing the blower.

What did we see? Up unti 4000rpm we saw a an almost identical 20rwtq gain. Since we know that both motors have similar flow capabilities it follows that blower efficiency has fallen off slightly above 4000rpm.

Remember. Both of these dyno tests were done in an attempt to show the cars in the best possible light. There were no attempts to cover up anything or make anything look any better or worse than it was. Both were done on nice days with good air. Neither test was done with anticipation that they might be compared to one another some day, they were done over a year apart.

Shall we continue?

What about the raw numbers? People have stated several times above that different cars, different dyno's ....... ect. I hear ya.

However.

Both of these cars are well documented on the race track. The MPIII car ran 12.86@111.1mph at the SC Shootout immediately following it's dyno session. This calculates to 353rwhp.

The S-Port car ran 12.90 @ 108.2mph at the V6 Challenge immediately following it's dyno session shown above. This calculates to 335rwhp.

So, do the 1/4 mile times match the dyno numbers? Do we agree that both of these cars performed as expected?
 
I would expect minor power differences between an S-port/mpII against an mpIII below 5,000 rpm. But I would expect the mpIII is optimized to make much more power above 5,000 than the others as it's capacity to move air efficiently is best above this range. In essence, the mpIII is not going to make a whole lot of difference below the max inlet air flow capacity of an S-port/mpII- the mpIII flows nearly the same up to a certain point until the higher air velocity/volume requires larger flow and a larger inlet- this is where the mpIII inlet gets much bigger and supports the higher flow with max efficiency.

I would also reason that on a stock motor an mpIII is not going to make a whole lot of difference from an S-port/mpII (both at 10% OD), but if the mpIII is very heavily overdriven, you might see some crazy torque numbers, and maybe even higher hp numbers that never could have been achieved otherwise on a completely stock SC motor. the mpIII is definitely much more efficient at higher air flows and it's designed to be heavily overdriven, which is where the mpIII will be superior to the other two.

Just my opinion, which maybe only worth 1 cent.
 
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Ok so what is being said is for a highly modded m90 blower to really give gains is that it has to be really overdriven and the engine has to turn a lot of r.p.m.s. or did I miss something again? Wouldnt it be better if a blower could make power without being driver so fast and at less engine r.p.ms.:confused:
 
XR7 Dave said:
In regards to the blower porting. The S-port is a very mild porting job. It is the standard port match done by Magnusen and repeatable by anyone with a couple hours and a dremel or die grinder and it fits the stock 94 plenum.

On the other hand the MPIII represents the epitome of M90 porting technology. It has been upgraded in every way possible to take advantage of everything we have learned about these blowers over the past 15 years. The case has been cut and modified and it requires a special inlet.

I figured if there was a real world difference to be seen, then these two blowers would make it obvious.

If the club really wants comprehensive testing done all they have to do is pony up the cash for the dyno and ship the blowers to one location where a suitable vehicle and witnesses are available for testing. However, that was not the intent of this post.


I was asking people to discuss the dyno charts in question.



What do you notice about the first chart? Well first of all you see a linear gain from the MPII to MPIII all the way from the initiation of the test to about 4800rpm. Average gain is about 20rwtq until (we assume) belt slip starts to eat into the power gains. How much of that gain is due entirely to the additional 5% OD? That is the question I was hoping to answer by posting the chart of another test done without changing the blower.

What did we see? Up unti 4000rpm we saw a an almost identical 20rwtq gain. Since we know that both motors have similar flow capabilities it follows that blower efficiency has fallen off slightly above 4000rpm.

Remember. Both of these dyno tests were done in an attempt to show the cars in the best possible light. There were no attempts to cover up anything or make anything look any better or worse than it was. Both were done on nice days with good air. Neither test was done with anticipation that they might be compared to one another some day, they were done over a year apart.

Shall we continue?

What about the raw numbers? People have stated several times above that different cars, different dyno's ....... ect. I hear ya.

However.

Both of these cars are well documented on the race track. The MPIII car ran 12.86@111.1mph at the SC Shootout immediately following it's dyno session. This calculates to 353rwhp.

The S-Port car ran 12.90 @ 108.2mph at the V6 Challenge immediately following it's dyno session shown above. This calculates to 335rwhp.

So, do the 1/4 mile times match the dyno numbers? Do we agree that both of these cars performed as expected?

Dave,

It looks like both cars performed about the same up to 4000 rpms, they each reached 300 rwhp at about the same point. The S port car was actually slightly ahead of the MP car at that point. Still not sure where you are going with this.

Yes I think the track times are consistant with the dyno numbers.

David

PS: For what it's worth, my latest dyno pulls show I don't reach 300 rwhp until 4700.
 
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Swade said:
Unfortunatly these are on different motors so its not a perfect comparison but still a very interesting comparison. How much boost was produce for each example given?

The S-Port was making around 15psi, MPIII around 16-17psi.

SCaddict said:
Has anyone put a MPIII on a STOCK motor and tested for power increases? I know that modded cars have done it, but I am curious about a stock motor with stock cam, heads, IC and all that jazz.

The MPIII has been run on a stock motor but I have not seen any comparisons to other blowers on the same car.

hytorksc said:
But I would expect the mpIII is optimized to make much more power above 5,000 than the others as it's capacity to move air efficiently is best above this range.

This point is well noted. Unfortunately we are still waiting for hard data to back that up.

tim said:
Wouldnt it be better if a blower could make power without being driver so fast and at less engine r.p.ms.

That's part of it.

David Neibert said:
Dave,

It looks like both cars performed about the same up to 4000 rpms, they each reached 300 rwhp at about the same point. The S port car was actually slightly ahead of the MP car at that point. Still not sure where you are going with this.

Yes I think the track times are consistant with the dyno numbers.

David
You guys are heading in the right direction with these observations.

Hint:

S-port car's cam has .513" lift. Basically a CMSI cam.

MPIII car has a Dr Fred cam with .520" lift.

Both cams are from trusted sources and both were designed specifically to be street cams with strong midrange and 5500rpm maximum rpms.
 
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