NTPOG Underdrive Pulley Review

Author: William Howell

Initial Impressions
I was originally going to order an Unorthodox underdrive pulley, at least, that's what I thought I ordered. I bought it through Danny's Import Service from a friend of mine. Anyway, I told him that I wanted an Unorthodox pulley, and when I picked the pulley up, I noticed that it didn't come with anything. No box, instructions, or stickers. I gave Top Speed a call (his supplier), and I found out that they don't carry Unorthodox. However, Anthony told me that they carry a knock off that is CNC machined from the same type of aluminum and is made to the same specifications as the Unorthodox. After looking the pulley over very carefully, I decided to go ahead and install it (I bought it for a really good price, so I wasn't complaining TOO much). The pulley looks like a very high quality piece. It even has timing marks on the larger diameter pulley. The new pulley is, obviously, smaller in diameter, but the picture doesn't show the huge difference in weight. I would estimate that the stock pulley weighs FOUR times more than the underdrive pulley. Here is a comparison of the new (left) and old (right) pulley:


Installation Impressions
My best advice is DO NOT install this pulley yourself. Todd and I had an 18 inch breaker bar with a 2 ft. cheater bar on top of that when we tried to remove the stock pulley. We were flexing the hell out of the breaker bar, to the point that both of us were convinced that we were about to break either the breaker bar or the 1/2 inch drive extensions. I decided to take the pulley to Danny's Import Service and have them install it. In the end, I was very happy that I took it there because it ends up that you have to drop then engine a little to get the pulley out. Plus, reaching the adjusting bolt for the alternator is almost impossible without an air ratchet. Here is a picture of the stock pulley when the car was on the rack (note the long breaker bar on the Honda tool for the pulley):


Once Jason got the engine lowered a little, he put the Honda tool on the pulley (see the above picture). He had to use a 2 ft. 3/4 inch drive Snap-On breaker bar with a 3 FOOT cheater bar to break torque on the stock pulley. It took a few tries, but finally torque broke on the pulley bolt. After that, the pulley easily slid off of the crank. Here is a picture of the installed underdrive pulley:


Now it was a matter of finding the right belts to fit. The belts that Top Speed and Unorthodox recommend DO NOT fit. They are too big. Both recommend using a Gates 060408 (alternator and a/c) and Gates 040410 (power steering). We ended up using a Gates 060390 and Gates 040395. The 060390 barely goes on, but once you get it past the lip on the pulleys, it fits like a glove. Both belts leave plenty of room for adjustment, and the Gates belts are some of the best belts that I have seen.

Performance Impressions
Once we got the belts adjusted and double checked everything, it was the moment of truth. The car started without a problem, and idled fine. We checked the alternator and it was putting out a steady 14.4 volts at idle even under a slight load. I went out behind Danny's where there is some industrial buildings to do a few 0-60s on the GTECH. I really botched the first one up, but the second one was a 6.29 sec!! I am sure that is a fluke, but I have not tried to reproduce it yet. I decided not to do anymore runs because of the amount of traffic.

The engine seems to pull slightly harder in first and second, but there is a noticable difference in third gear. Also, throttle response is greatly enhanced. One benefit that I like is that the A/C no longer drags on the engine so much. The only side effect to this is that the A/C is not as cold at idle. When driving around, the A/C is as cold as stock, however when idling, the A/C is slightly warmer than stock. Not really a problem in my opinion, even with the hot Texas summers.

I have now had the pulley on for about 10000 miles, and I have had absolutely no problems. I have been sent e-mail concerning the AEM ad that states that the crank pulley contains damping material that is "critical to engine life." True, the stock pulley is potted in a rubber compound, but I suspect this is to damp vibration from the p/s pump, the alternator, and the A/C kicking on and off. I haven't noticed any increase in engine vibration and engine sounds fine at idle and WOT. I am not saying that the guys at AEM don't know what they are talking about, but on our particular application, I don't think that changing the crank pulley will affect life at all. Also, the crank pulley is not a harmonic balancer; that is what we have the twin balance shafts for. There is much debate on this topic, and this is just my opinion. If you ask three different people, you will get three different answers!

Update- READ!!!
Since the original writing of this article, a few of us with these pulleys have done much more research. Billy has recently had his engine built up by Larry at Endyn. Upon dissasembly of the engine, Larry reported that the bearings, with 40k miles on them, looked like they had "a hard life." Roughly 20k of those miles were before the pulley, 25k of them after.

We have no idea what the bearings from a 45k mile engine are supposed to look like, but by comparing the #1 bearing to the #5 bearing in Billy's engine the difference is stark. The # 1 has deep grooves which have worn away all the original machining marks, still visible on his #5 bearing. Larry also reported that his oil pump was so damaged as to be unusable. It is possible, though unlikely, that overly tight belts may have contributed to this.

While we aren't going to detail all the arguments for or against pulleys, or tell you what you should do with your daily driver or track-only car, we (and Larry feel that the damage in Billy's engine far outweighs the benefits seen by the pulleys. We (including Larry) feel that the "accessory" pulley kits offered by companies like Unorthodox should NOT cause the same damage we think the crank pulley did- the harmonic balancer is weighted and damped to absorb the impulse energy created by the accessories as well as the crank itself; while changing the pulleys on the accessories will alter the characteristics of the load, we feel that any change would be a positive one. - Todd Marcucci

For comments or questions, e-mail me.

This page last updated 4/3/01.