I am very interested in he Alta crank pulley but the debate over engine longevity is concerning me....as others. But what is the risk? Are we talking a bottom end rebuild..new bearings and crank?......or pistons through the top of the head.....thrown rods etc.

I know that Randy Webb is evaluating as well as Rhyphile. My car is not my dailey driver ( but I drive it almost everyday) I really enjoy the performance......I am trying to get all the hp/torque/responsiveness I can without NO2 or turbo. So what is the downside risk and what will that cost to replace/repair/rebuild/fix?

Additionally, I am planning a light weight flywheel......how does this factor if at all?

 

Im pretty sure it would not mix well with your 19% pully as the boost pressure and the rpm of the supercharger would go well past the critical point! Heat buildup, detonation, ect..

 

I am not going for an oversize but the same size as stock....or possibly a 2% and reuce my pulley to 17%

 

there are two schools of thought:

if you do not dampen the torsional pulses in the crank, you may experience crank failure. this is a problem addressed by the stock dampener. the problem is exacerbated by pushing the power limits higher.

the other point of view is that the problem is over-rated and that the mini engine is so strong it is not affected by torsional vibrations, and that the sc and belt system tend to dampen vibrations.


as the race track has proven time and time again, you have to find out empirically; everything else is speculation.

the missing factor that would help:
long term use reports with high hp Minis using no damper;
maybe some comment from a racing mini about crank failure, if at all (Nuzzo?)

 

A source told me that Nuzzo is not in favor of the crank pulley.

another source told me that the engine designer himself said that they ran the equivelant of 100K with no dampner with no ill effects.

I am not racing this car and the duty cycle is relatively low. I would suspect keeping a car at 5K and higher for the duration of a race over and over would be far harder than spirited driving in the mountains. Frankly, when I am in the mountains I do not run full out on the straights......I just enjoy entering and exiting the turns......I'd like the throttle response to be quicker.

 

I've done five track days so far and in between use it as a frequent around town driver with the lightweight Alta crank pulley. So far the motor is running as sweet as ever. I am putting the 3% on this weekend. It's slightly heavier, but still just around 17oz.

I know that this is not a real long time, but I may be one of the longer runners of this pulley that actually post here.

 

You are one of my kindred spirits.....if we go down we'll go down together....I'll order the part on tuesday.

Thanks

Bob

 

Why would you reduce down to 17% and add 2% at the crank? All you're going to do is overdrive your other accessories and get the same RPM out of your SC (hence Same boost), aren't you? I'm no mechanic, but the math would seem so.

 

The 19% pully is hard on the belts because its so small, the reduced contact area of the belt promotes slippage.

 

exactly

 

Yes, but you will be making boost the equivalent of a 21% pulley.

 

Spider, ive got the lightweight alta crank pulley + 17% sc pulley on on my car and I will tell you what I noticed with it. Overall, not a whole lot of improvement over just the 15% sc pulley. The intercooler outlet temps were so much higher with this pulley, that I dont know that it really makes enough power to warrant the amount of heat it produces. I did notice the power coming on a bit earlier (maybe 500-1000 RPM) and much smoother.

However, this really doesnt apply to you since you will be going from a 19% to this. Let me know what happens when you get it installed.

 

Interesting. You should have Alta address this in their Q&A thread. I'd like to hear their response.

 

Steve (Steve's Auto Cinic) put the 2% larger crank pulley on my MCS last week. I already had a 15% reduction pulley, so now I'm at the functional equivalent of 17% reduction. But it's better than straight 17% due to increased size, though not very much, of the crank pulley. . .you know, the belt issue.

My car's a daily driver, but I drive it hard. So far I'm happy. Power kicks in about 500 rpm earlier and the boost gauge registers a max of 16-17 psi compared to 14-15 without. (no skepticism please. . . I'm just talking about what the gauge registers).

We're not talking huge gains, like the original pulley install, but it is noticeable and not expensive.

 

Why... it's nothing specific to their product. Spinning the supercharger faster = more heat. Everyone understands that right?


I'm a little disappointed to see people continuously asking to be talked into buying a crank pulley. The results are always the same... a bunch of speculation. If anything, I would expect to find uneven bearing wear. It's more of a lifespan-shortening thing than a catastrophic failure. That's why noone has any real proof that anything is, or isn't happening.

 

Because JCampos seems to think that the gains are negligible with the added heat, whereas I have not heard this response from people with a straight 19% pulley (from 15% or 17%). If the heat from a -19% SC pulley and a -17% w/+2% crank pulley are going to exactly the same than I guess it isn't worth discussing. But if that's the case, I didn't know that for sure, so that's why I mentioned it. In any case, he already owns the pulley, so nobody's trying to talk anyone into anything.

 

Just went for short test drive with my new Alta 3% crank pulley. I am running a 15% SC. What can I say, just felt a bit better. I'll know more when the car gets tuned in a week. New injectors coming also.

 

I will pull the 19% off and replace it with a 17 or 15%

 

I have the Alta IC........that should help keep the temps down..... I see you have one too hmmmmm

 

Although I quoted you, the bulk of my reply was to the original post which was questioning the general effect of the [lightweight] crank pulley with no mention of increased diameter or heat.

I guess my cynicism on this topic comes from seeing these threads pop up year after year on messageboards spanning multiple auto makes. I've only seen one post ever that presented any evidence - and that was quite open to debate as well. One individual, quite a few years ago had pictures of the main bearings out of his H22A (honda prelude) engine after running an Unorthodox Racing (lightweight aluminum) crank pulley for some period of time (I forget how long). His pictures showed considerably more wear on the bearing immediately adjacent to the crank pulley. His conlcusion was that the crank pulley was evil and he would no longer use it.

The discussion immediately broke down into a debate about the balance characteristics of the H22 engine vs the more popular B18 (integra) engine and how the H22 possibly suffered from poorer internal balancing (as evidenced by Honda's decision to include a balance shaft). In the end, I speculate the only person who was convinced of anything was the original poster.

I understand everyone's desire to locate solid evidence, but it's just not out there to be found.

 

Here's my anecdotal data: I have the stock-size lightweight pulley. While I haven't put a lot of miles on it I've run about 70-80 autocross runs with it. I've had zero trouble. I think that it helps in situations where you're down in the rpm band to accelerate as there is less rotational mass.

 

I had a question about using it with the light flywheel but apparently this is no big deal.

 

..... I know, I know, .... it's a 'butt' dyno, but I'm a happy camper once again.
Just got back from a breakfast run with my son. He mentioned it before me but when we pulled onto the highway he just looked over with this big grin and said, "man this car really goes!" Thing is I didn't even get on it, but the fact is that you can really feel that stupid little 3%!. I can hear it in the Alta intake and I can absolutly feel the power. I'm actually quite surprised.

Next week are the injectors and then the Unichip tune with a very experienced race shop. Over the winter I'll do the final head and cam thing and that should be it for me.

 

very cool

 

That will be it? My son, you have no idea of the power of the dark side of the force. After the head/cam won't you need better airflow ala throttle body, header? Then comes the dark thoughts of twin charging or twin screw blowers.