Tempo Accessory Drive Rework

[Frank Lee]

It's not an alt delete; it's not an electric water pump or electric power steering...

It's a simplification and re-ratioing of the accessories and the drive belt system that with any luck will show a modest fe increase.

The Coupe's radiator started leaking so I pulled it out. Suddenly access to the engine accessories radically improved. This set into motion a chain of events that I probably wouldn't ever get around to otherwise: reworking the accessory drive system.

I removed the a/c compressor; the a/c didn't work anyway and I have no desire to fix or use it. The condensor came out as well- this should improve the flow through the radiator too. There should be a nice weight loss from those deletes (weights to come).

Next up was the power steering pump. It's a small car and I'm not small... manual steering should be quite sufficient. It'll eventually get looped lines but for now the system is intact and the pump pushed off to the side.

The '92 has a 95 amp alternator. Especially since the a/c delete, there is no need for that much. Early Tempos with a/c had 60 amp alternators/ 40 amp w/o; and even that should be more than enough for mine although the earlies didn't have electric fuel pumps. Sure would be nice to throw a half-sized unit in there! I do have an older 50 amp alt from some random foreign car but have opted to keep the stocker and simply spin it slower... so far.

Lacking output readings from it at different rpms, I'm simply going to assume it's like the Delco units described in a Delco alternator paper I found online that say optimum efficiency is found at 2000-2500 rpm and 30-40% of max rated output. Engine rpm is 2000 @ 55 mph so anything down to nearly 1:1 should work if all idling is eliminated, and the way I operate the car, it pretty much is.

Car Craft "All about pulleys" says water pumps can be underdriven 25%, so I took that as my guideline, and figured I could even exceed 25% by some amount for my application based on not much more than 12 years of owning the car and not having any overheating issues even with the grille blocked off.

So now I have a simple three pulley system: crank-water pump-alternator and with the a/c compressor and power steering pump deletes, it appears I can also remove an idler pulley and an idler tensioner pulley. Woo Hoo! FOUR pulleys gone! It'll look like the 283 in my '59 Bel Air, only serpentine, and perhaps with the alternator spring loaded to become the tensioner... or else use an old-school manual tensioning system.

I wasn't about to spend the big bucks I see aftermarket pulleys selling for- not only that, I didn't see Tempo specific ones (not that I looked very hard) so off to the local scrapyard I went.

The easiest thing would have been to find an under-sized harmonic balancer but at about 4" diameter stock, I figured my chances of finding a smaller unit that would bolt on would be nil.

So I found a Windstar(?) alternator pulley that bolted right on to the alt, no mods whatsoever, for a 13% alternator rpm decrease. Car Craft says -10% causes no issues for most. It isn't the 50% reduction I thought I could get away with, but time will tell if it was the right move or not.

Found a water pump pulley from a Sable that's 33% bigger. The big pulley is plastic while the stocker is steel, so they feel about the same weight. The mounting bolts line up but it's a 6-rib unit vs stock 5-rib and space is at such an extreme premium that I'll have to cut the 6th rib off and go flangeless on the backside. It's so close to the block the belt has nowhere to go anyway.

Both my "new" pulleys are 6-rib while the harmonic balancer and stock Tempo stuff is 5-rib. No problem, I'm going to ignore that extra channel on the alt pulley. Perhaps, if there's a 4-rib belt, I'll try that.

The lack of idlers eliminates "back-bending" the belt; the new much straighter path should lower belt hysteresis losses. The larger drivens- as opposed to having a smaller drive- should also reduce hysteresis as the belt won't have to make those sharp little bends. The three remaining pulleys will have quite a bit less belt wrap and of course less hysteresis.

The jerky, heavy transient load of the a/c being gone may mean the system will work with less tension. That the new belt will be about 40% shorter may help some too. Additionally, the groovey side of the belt will no longer be stretching as it moves; only compressing and straightening. I think this will help reduce the cracking of the rubber there that these belts all seem to suffer up here. I'm told that a lot of that happens at -20F and lower.

Total cost so far is $10 for the two junkyard pulleys; next up is to fab a new alternator bracket and figure out how long the new belt needs to be.

It might be a stretch to hope for the "-10%" of an alternator delete, but the likely range of improvement should be between 2-10%???

Purely guessing (but somewhat educated guessing)... simple removal of a pulley should be good for at least .5%-1.5% loss reduction due to hysteresis (bending the belt rubber losses) plus spinning the pulley mass accel/decel plus the pulley stirring up air plus removal of any misalignment losses plus bearing losses- which even though are small, are something. The smaller the pulley deleted, the greater the gain. So deleting four pulleys could be 2-6%...

Add to that the savings from deleting power steering pump loads (whatever they were), and reducing alt and water pump loads. Any guesses on what that might be?

[CigaR007]

Pretty cool ! Where are the pics ?

By the way, wouldn't a manual steering rack require less force when compared to a powerless power-steering rack ?

Definitely looking forward to the end result !

[Frank Lee]

Perhaps I can add some pics tomorrow.

Yes, a manual rack would probably be the best, and although rare for this car, they do exist. However, being lazy AND cheap, looping the lines seems the easy yet effective way out.

On a separate but related note, the replacement radiator will be smaller than stock. I thought I was so smart with my stockpile of 4 Tempo radiators- a lifetime supply! Alas, three of them are the plastic tanked kind- as what's in the Coupe- and they ALL leak, and the local shop refuses to try to fix them. The fourth radiator is all-metal, from an '84. But since it's smaller, I'm also having to re-engineer the radiator mounts and electric fan as that stuff all changed from '84 to '92.

[slowmover]

I knew you were good at scrounging. I'm impressed that you found what you wanted (having spent many hours in boneyards; most old stuff down here was long ago sent to the electric scrap mills). I don't have a guess as 2-6% is low, but I will bet that the "feel", the "sound" of the car improves all around, not just steering. That should make for improved driver inputs as cues become sharper.

Starting to look like a big lawn rider under the hood?

Nice description of work.

.

[mcrews]

nice frank.
I was able to follow most of that.

Get pics!!!!

[ProDarwin]

I like this thread. These are some of the mods I have considered. I hope the results are pretty good.

Available for my car there are some relatively cheap underdrive pulleys that also weigh less than stock, but I want to go the junkyard approach as well. My car being a 12si GM alternator means the main body is shared with almost any FWD GM car made in the last 20 years, so there should be some options for a factory-underdrive, and the body could be swapped for a lower output 12si or a 10si. Hadn't thought of this until I read this thread.

Regarding the water pump, one of the other "under-drive" options I have heard of is (depending on the shape/style of the pump) to remove it from the car and cut off a few fins in a symmetrical way - i.e. if you have 8 fins remove 4 of them. I recall reading somewhere that the Neon SRT4 pump is a normal Neon water pump minus a few fins.

[Frank Lee]

Ha- me adding pics "tomorrow" = fail!

But I got it together today and survived the test runs. I used the big water pump pulley and the +13% alternator pulley. I welded up a new lower alternator bracket from angle iron, and modded a top bracket (with old school adjustment slot) from an old 327 Chevy engine. I put the old belt back on just to hold it tight and make marks on it, then went to the parts store to match one up. The belt ended up being 45% shorter than original at 48" vs 86".

Been driving this thing for 12 years now so suddenly having "Armstrong Steering" was a surprise, even though I knew it was coming! Only noticeable at stops/low speeds; on the road is functionally no difference at all. Will have to try looping the lines.

Once I gain experience and get comfortable with this setup, I will push the envelope further by re-mounting the old water pump pulley onto the alternator. Then the alternator would barely be turning faster than crank speed.

Junkyard pulleys: $10
Bolts: $1.95
Belt: $11.75

[zonker]

Good old yankee ingenuity...
I did the same thing a while back on my old 2.3 mustang, using a ford ranger crank pulley and a tbird turbo water pump pulley, with the larger alt pulley you describe.

[Frank Lee]

Did you notice any effects?

[zonker]

yes i noticed a small power gain, but i did not measure fe at that single change point.

it did help me to get that mustang to 540 miles on one tank of gas...