Hmmm, the cat's been out the bag for some time then. A certain tuner over here has had a larger crank pulley on their car for several months now. This is a good solution but not a revolutionary idea by any means.

Cheers,

Henry

 

I was just reading about that need:

http://www.nhrasportcompact.com/2003...er/112001.html

 

If you just happen to be the first to break a MINI crank or waste your main bearings it appears ALTA is ready to stand behind their claim that it can't happen because of this pulley, no need for a damper.
Harmonic's occur in all piston engine crankshafts, to brush aside years of research is, well you name it.
Do you have an accurate oil pressure gage? Keep an eye on it.
I just hope for your sake in testing the bleeding edge you don't have to find out.
For your reading pleasure;
http://www.indiacar.com/infobank/tor..._vibration.htm

While it is stated that a 4 cylinder engines critical speed is over 9,000 rpm (read as crank failure) and a torsional damper is not needed it is the minor critical speeds that take out the main bearings.
Here is what possibly the best engine builder/developer in the business has to say about torsional dampers.
http://www.theoldone.com/components/fluidampr/
I hope you understand, I wish you well and you did a great write up.

 

The wesite you gave us was great info, but this is also talking about old stuff, where cranks weren't balanced down to 3 grams! I don't think they even knew what grams were back then! Just kidding! But now a days, the cranks are balaced on $100K machines that are accurated down to .5 grams.

The second article is also talking about Honda's and their specific engine design. Also notice the HP they are talking about having the failures at, 400+. The mini is no where near that HP and tourqe. I know of many hondas that have a soild type crank pulley (using honda's because they "in thereory" are one of the worst offenders when it comes to soild causing failures do to their long stroke design) with 100k plus miles and no problems. Even a friend of mine has a SC integra with literally 80k with the SC on it, and soild crank pulley, and numerous track days, drag races..... and no failure!

I think we can go back and forth all day about if they will cause issues or not. This is something only time will tell.

 

Regarding the larger crank pulley, by no means were we saying we invented something new no one has ever heard of. With all the talk about making a bigger one, i figured it would be a good time to tell people about the pulley we have been working on. Look out for our 2%-4% larger pulley for sale in a month or so.

 

ALTA2, I appreciate you coming-on here, and your frankness (time will tell).

How many of these have you sold to the MINI community, and when was the first? Also, were there any reported problems as of yet? It would be nice if other such pulley owners would chime-in here...
Since it really seems that the jury is out of this one, at least for some/many of us, providing such answers would be helpful. Thanks.

 

I would definitely be interested in a larger lightweight crank pulley. It will help me pull every little bit I can out of the car. Thanx for all the info guys .




Thanx again
Danny

 

Danny, just wondering what you have that has given you 215 Whp? Maybe you have already gone into this, so if you have just point me to the thread.

Thanks!

 

I can't remember the thread, but here are my mods:

P&P Cylinder Head w/ over sized valves
P&P Intake Manifold
P&P Intercooler runners
P&P supercharger
Schrick Racing Cam
Custom made adjustable timing gear
63mm Throttlebody
Larger top mount GGR Intercooler
Screamin deamon ignition coil
Nology Wires
I22 Spark plugs
400cc injectors
Madness 15% supercharger pulley
Milltek Header
Milltek Catback exhaust
GIAC software
Lightweight flywheel w/ uprated clutch

Coming Soon:
Larger crank pulley - Alta
Apexi S-AFC
Pilo racing pistons



Danny

 

Jeff Perrin and I talked about the crank pulley on the phone for quite a while yesterday.

My utmost concerns are essentially thrashing the engine with harmonics and power pulses it otherwise wouldn't see with a high-inertia rotating assembly and a harmonic damper. Of course Jeff couldn't refute that removing the damper would not transmit some increased vibration to surrounding components (bearings, cam chain, accessory belt), the specific design of the engine (i.e. well balanced assembly with firing pulses ever 180 degrees and a very short, strong crank) tends to lead itself to having minimal inherent resonances. This I can understand.

The other aspect is damping the "power pulses", where each compression slows the crank, and each combustion speeds up the crank. Reducing your rotational inertia makes the crank speed vary greater over the combustion cycle. What you end up getting is a crank speed that can resemble a sine wave (though that's just for illustrative purposes). The lighter the rotating inertia, the bigger amplitude the speed variance. This would be relatively fine if there were nothing else connected to the crankshaft, however the valvetrain, the accessories, and the clutch, are. Engines that don't make a ton of power (read: us) don't have enough power in the combustion to vary the speeds that much. Basically, long story short [too late], is there is a practical limit to how much inertia you want to remove from the crank assembly. If you have a lightweight crank pulley, there's probably no need (or desire) to get a lightweight flywheel. You want mass somewhere. If your rotating mass is too light, you end up jerking the chain of the valvetrain, as well as yanking on the accessory belt more, and stressing them more.

Getting rid of some mass in the crank assembly isn't a bad thing. Getting rid of too much can lead to stressing your timing chain and accessory belt and engine bearings to the point of failure. The inherent balance of the rotating assembly is critical too, and according to Jeff, Tritec has done a great job with that. According to Jeff, the MINI, specifically, doesn't benefit much from a harmonic damper, and that removing it will have only a minimal impact on longetivity. Jeff also said that certain engine configurations (like V-8's and I-6's) have very bad resonances in their crankshafts and need a harmonic damper, and engines that tend to have more compact cranks (like the MINI, WRX, EVO) don't really benefit from a harmonic damper.

All that said, I still want to rig up a sensor that graphs the speed of the camshaft, seeing that varying waveform based on power pulses, with and without the added mass and harmonic damper. Anyone have a solution to do that?

 

Very well-thought-out argument.

If the MINI engine is internally balanced, why does it have a vibration damper assembly on the crank at all?

 

RYEPHILE,
Good talking to you yesterday, it sounds like we are on the same page about the mini engine not needing a dampener.

In the end, yes i am sure there is some extra wear on the bearings caused by no dampener, but the many cars with more than 80k on them shows its not that big of a deal. Esspecially considering that the smaller pulleys everyone has are going to cause more wear on the engine than this. I would hope that everyone has considered this when they are modding their car.

Putting a speed sensor on the cam shaft and comparing it to the speed of the crankshaft would be pretty cool to see. The problem is i don't think there is a good way to do it acurately. What i mean is the changes in speed might only be 10rpm. And tapping into the crank sensor to get the crank speed is very hard to do with out messing up the signal going to the ECU. I have tried this and its not as easy at you think. Then rigging up an accurate sensor to the cam might be kind of tuff since it is a chain type that is barried under then valve cover. But if you can come up with a good way to measure it let me know, i would be very interested.

 

The difference is in damping torsional oscillations versus counterbalancing the internal reciprocating assembly. Certain engines due to their design (mostly V configurations with cast cranks) cant be fully balanced by the bobweights on the crankshaft, so the crank pulley/dampener and/or the flywheel/drive plate/torque converter are constructed with a radially offset weight which compliments the bobweights on the crank to fully offset and balance the reciprocating assembly. Inline engines with even numbers of cylinders can generally be fully internally balanced. The MCS engine benefits from having a forged crank which is heavier than an equally sized cast crank, this allows for a slightly smaller sized set of bobweights to balance out the reciprocating (pistons/pins/rods) pieces.

A harmonic damper is still needed on some engines (especially those with longer cranks) to quiet the unwanted twisting forces imparted to the crank by the power pulses coming from the cylinders. The MCS damper is made not only to dampen the usual torsional oscillations at higher RPMs, but also to keep the characteristic 'rpm wobble' that all 4 bangers have at low idle from being transferred to the accessories and especially the supercharger, which has a rather large rotational mass due to it's being overdriven through the belt and pulleys.

 

re-aninating Rajron's link:

http://dinancars.com/whitepapersFile.asp?ID=5

 

Good read, thank you.

 

Thanks everyone, its been a great read. Lots of good info.

Just one quick question. I want my MCS to last, I mean I'd like to drive it for 100K+ miles. I'm planning on going with the 15% pulley soon enough, along with some other popular mods. Should I even consider changing the crank pulley if I have no plans of tracking the car?

 

I will fix that supercharger wobble..... I will just junk it and go to a straight turbo......

 

Just thought I would chime in here, I have the Alta 15% pulley, Rear Sway Bar and Air Intake. Alta's machining work is really top notch, as are their other products. Kudos guys, I am very happy with all of my Alta Parts. They almost seem too nice to hide under the bonnet!

 

Well I talked a bit today with the lead engineer for the Tritec project (benefits of living in Detroit). I asked his perspective on the possibility of removing the crank damper in the name of performance. He agreed it would provide less rotational inertia to overcome, and thus quicker revving, more power to the wheels.

During Tritec's testing phase, one of their engineers took it upon himself to try to break the crankshaft (just to find the limits), and to his frustration, he couldn't do it within the parameters of the stock engine configuration (even w/out the damper). The fact that they could not get the engine to fail is a tribute to what we've found out so far; the MCS long-block is a brick-sh!thouse.

Another interesting tidbit; he told me that the MCS's damper is tuned to a very high frequency, and in fact the accessory belt will end up damping most of those high frequency harmonics before they'll harm anything.

Long story short [too late! ] Getting rid of, specifically, the MCS's damper isn't a bad idea. This is coming from the horses mouth, sort to speak, the team that developed our engine!

A final word he told me, was there could be a slight increase in percieved NVH, and that this may or may not be objectionable to the driver. From what Onasled says, his MCS runs smoother than before. Now honestly I can't say that makes much sense, but perhaps he was just expecting it to be rougher, and it was smoother than he expected. We honestly can expect some reduction in longetivity, due to those very high frequencies not fully being damped out, but I think most of us that will be installing this pulley will have our engines torn apart and re-built before the crank pulley will cause an issue.

Well, that's what my investigation has uncovered so far.
I hope that provided some insight as to why the MINI, among other short crank engines, can get away with not running a damper. That said, I have one of ALTA's new crank pulley's on my desk. Once I get my puller tools from Classic MINI, I'll give you guys some install and before/after dyno plots, NVH perspective, etc.

Cheers,
Ryan

 

Great post Ryan! Just what I needed to hear, being that I'm suffering from Mini installation depression, commonly know as MID.
Actually my statement was "...Car runs as smooth as ever!" I was just trying to get across that I notice absolutely no difference with this pulley as far as vibrations of ANY kind.
I know you'll be happy with yours and look forward to hear from you soon

By the way, what is NVH?

 

You're welcome onasled; I've tried to get as many perspectives as I could on the subject.

NVH = Noise, Vibration & Harshness. A common ackronym for automotive chassis, suspension, and acoustic engineers. A new ackronym (you heard it here first, maybe) is BSR, for Buzz, Squeak, & Rattle (mostly for automotive interior people)

Cheers,
Ryan

 

OK, ... well absolutly no NVH here!

 

Good Morning Ryan....

I have to say I was in the ney sayer camp on this one, but with your thorough
investigation, with more to come, I'l be looking in to getting one my self....

Good job

 

Would there be a larger interest in a Lighter Weight (Then Stock) Harmonic pulley? I have been approached by a MFG who claims this. I am waiting for info to back it up.

 

Ryephile,
Wow, great research! I am glad the engineer back up what we have been saying all along. When i first started reading the post i was thinking oh great, here it comes, no one will ever trust us again. Thanks again for taking the time to do the research.

I heard from an SRT supervisor at Chryslers, a long time ago, that Tritec put 2 of the SC in line and ran 30psi or something and the pistons and crank held up to that. So the engine is bullet proof, now we just need to get something that flows more CFM than 15% pulleyed SC!

Alta