+1
I have the Alta professional pulley puller, and after doing 7 pulley installs, it's worked like a champ. The only thing I would have done differently is that if I had known I would end up doing so many pulley installs, I would have gotten the pulley removal tool from Outmotoring that doesn't require removal of the tensioner assembly to install the pulley.

 

is the gain between a 15% and a 16% really that noticeable?

also, would you need injectors with either of the two?

 

Well, at any given engine speed, the 16% pulley would be spinning the supercharger about 6% faster than the 15% pulley. How the additional supercharger speed would translate into additional engine power is a more-complicated issue, but it's not going to give you anywhere near an additional 6% increase in horsepower or torque.

As for the injector question, I think the stock injectors in either case will be able to provide the required mass of fuel, at least up until the very top of the RPM range. If you're going to be spending a lot of time at very high engine speeds, larger injectors might not be a bad idea, but for daily driving or even autocrossing, they would likely be overkill.

EDIT - which brings me to another point. Not all horsepower increases (even increases that can be shown on a dyno) are useful in real-world driving. As an example, since the torque curve on a MINI is relatively flat, even at higher RPMs, you can pick up a few extra horsepower by raising the rev limiter. The problem is, you'll never see that increase in the "real world", unless your driving involves engine speeds in excess of the original rev limit. Personally, any time I see "before & after" dyno plots, I mentaly cut off anything on the charts past 5500 RPM or so, since that's about the maximum engine speed I see, either on the street or at an autocross event. I'd *much* rather perform a modification that gives me 2-3 extra horsepower *througout the RPM range* than a modification that gives me an extra 10-20 horsepower at the upper end of the RPM range where I spend very little time.

 

Couldn't have said it better.

 

Scott- You my friend have hit the nail right on the top it's head and then some. Believe it or not, this was exatly what I was thinking about the other day. All this high end WHP talk and increase in engine power with raised rev limiter and what have you is sort of an overkill if ou ask me. I mean sure, who does't like more power, even if it is in the high ends but realisticaly, how many times do you spend your time/driving between 6-8k rpms? Like you said, most driving around town and or street driving and occasional auto x is done under 6k rpms. Don't get me wrong, I do drive hard and push the car but I do not red line my car everytime when going through all the gears from 1 to 6th.

I would love to get that extra trq and power between 3-5k rpm. I like to see a tune followed by a dyno test that shows a nice delta between those rpm ranges. Something around 185-190 trq between those rpms would be best in my opinion.

 

Well stated and very true....What if we called it usable HP? I think that is why in most test I've read the 15% was found to be the most efficient size across the board.

 

Well, I wouldn't presume to try to define what "usuable" horsepower is, because there are people for whom a few extra horsepower above 7,000 RPM can make the difference between winning and losing.

As for the supercharger pulleys, I would think that for a car that's a daily-driver (or even an autocrosser), a 16%, 17%, or even 19% pulley might be a better choice. You'd get the increased horsepower and torque down low, and if you rarely see the high side of 6000 RPM, you wouldn't have to worry about needing bigger injectors, overspeeding the supercharger or water pump, or getting the "check engine" light or throwing "overboost" codes on the OBD computer, like you would with a 19% pulley on a race car that routinely sees engine speeds in the 6800-7000 range.

 

FWIW, I've got the M7 16% on my 2005 MCS and I've got a lean condition at WOT that's pretty serious. It's detonating with 91 Octane. With 104 Octane racing fuel it's fine, but at $54 for 6 gallons, it's not a good solution when I fill almost 3 times a week.

Though I just heard from a friend with the same issue on her '05 MCS that larger injectors solved her problem--I'm fully aware of the issues of larger injectors and stock ECU software actually leaning out the engine even more...

I'll know in the next week or two if it solves my problem as well.

Richard

 

Your right...I quess I was relating to track type situations or maybe canyon carving where you are running the car in the mid to higher RPM ranges. If your talking stoplight to stoplight or drag racing a 19% or 17% prob. would be better as you get the power lower in the RPM range...

 

hmm...now this is getting me worried. let me know how it turns out. this guy who does dynapack tuning for any car said i need larger injectors for the 16% pulley (and of course, i would need to have it dyno tuned by him). i actually started a thread about my first batch of mods and included injectors as one of my questions, and almost if not all said i don't need em with the 16%

 

a 16% pulley shouldn't be throwing lean codes all the time, nor should it knock much. I run one as well, and what he's decribing isn't consistant with the parts he has on the car, if all is working properly.

OG, did this show up with the pulley, or did it creap up on you. Most timing related knock can be dealt with via the ECU knock detection loop. I've found that carbon build up doesn't act the same way, as hot spots light off the mixture indepenant of time. Do you ever get a miss-fire code? If so, is it just one cylinder or random? If it's cause you're running lean, check the fuel filter first. See if there's a place that does injector cleaning, and yank yours and get them cleaned (you'll get an idea of the flow match as well... FWIW, mine were almost 5% peak to peak variance before cleaning, just over 1% after) Injectors have filters that can clog, and the little needle that is the valve can have deposits build up. If the fuel filter is clean, and the injectors are flowing well, then it's definantly carbon. Time for Sea-Foam!

If the knock can happen at pretty much any RPM, it's not the injector capacity, it's something else. If it just happens as you near red-line at WOT, then it could be a flow issue, but I'd guess that cleaning will make it all go away.

If you need a set of stock injectors to screw with (did you turn yours in for cores?) just PM me and I can send them to you.

Matt

 

I agree with Dr. O! 16% pulley shouldn't be running lean at WOT are you running a reduced crank pulley with that?

 

As far as I know, no. Remember I bought this MCS secondhand from a NAM member. My friend, Bar10Girl, also bought her MCS secondhand from a Porsche owner, and it was only like a week old when she took it over. Both of our cars run lean when under load. I'm not saying it's because of the 16%, but in my current configuration, of 16% and Alta Intake and before the DT BPV and Invidia Exhaust, I've been detonating to the point of getting SES lights. In the most severe cases it happened when I was already at speed and trying to pass someone, and usually with the AC on. On two separate occasions the SES light flashed, and the engine would quit.

Of course, when I was throwing the most codes, it was due to corroded spark plug wires--which I changed out--and that stopped the misfires. I haven't had any SES lights in awhile, but of course, I don't push the engine when I hear it detonating. I'm no where near redline either---happens around 5,000 rpm.

The first time I noticed it, the supercharger would spool up (rise in pitch the longer the gas was held down) and abruptly cut off and rise in tone and cut off--like it was trying to spool up but couldn't.

Bar10girl had hers on a Dyno this past week and did some changes to her injectors that solved her lean condition--so I'll be trying the same and will report back. Thanks for all the suggestions. I've consulted quite a few engine experts all with different suggestions, so for now I'll stick with my trusted friend with a MINI.

 

Please do keep us posted. I would be interested to hear what you find with that. I have only dealt with on 16% pulley install but we ran the car hard (the guy runs tracks all the time) and it did very well, so I am curious.

 

Exactly: Even at 6800 RPM most of these tunes only 4 -6 more HP and 8 FT/LB of TQ at their peak. Certainly not worth a $700 dyno tune. Dyno tunes are for folks with more mods, like heads.

 

both helix and webb will loan you one of the pulley tools I made for them if you buy the pulley from them. The design does require the removal of the tensioner assy. , but the job can still be done in an hour (or less) Webb has a great "how to" on his site.Good luck