Originally Posted by Oldsm
Are underdrive pulleys just waste of money?
How about holley sniper? It is only east way to drive with moderate mpg or can it give good mpg? Example with vortrc heads and cam.
The Sniper is a high pressure TBI, like the GM TBI you have it is targeted at replacing carburetors, like any TBI or carburetor for that matter equity in cylinder to cylinder fuel distribution is a problem, so the mixture ratio is set so the leanest running cylinder is correct so these are never as good as port injection as that eliminates the weird things that happen to mixtures between the device and the valve.
Under drive pulleys are intended for high flow coolant pumps that deliver more flow per RPM so don't need to spin so fast. They also tend to result in low alternator output as it spins to slowly. Here again for a stock coolant pump, they just don't consume much engine power till you get the engine constantly at or above 4000 RPM. The pump uses fractional to onesie, twosie horsepower in its normal operating range, once again the resultant savings, if any, make it hard to justify the cost except in the minds of advertising executives.
Unfortunately magic fuel burn savings just aren't there against the cost of chasing them. You may end up at the pump spending 48 Euros on a fill up instead of 50, but the 2 Euros saved against the cost of the modifications to get them takes a long time to recover. Been there, done that; as before I retired I did a lot of driving and really worked on getting fuel burn down. As in San Diego to Newport Beach 160 miles each day; Snoqualmie to either to Auburn, Everett, Kent, Renton, or Seattle every day those are from 60 to 100 miles a day. When my friends and I opened our shop in Smohomish I ran parts between there and the machine shop in Centralia that's 240 miles on I-5 at least once a day, so yeah I know about big gas bills.
I know many crazies that pursue high mileaging to the edge of sanity, it can be done but it ain't comfortable and in many cases plain unsafe. I had a neighbor in Snoqualmie a few decades ago, he put a Fisher carburetor on his Dodge van. The Fisher lacked a power enrichment circuit which if you live in flat country and keep an egg between your boot and the accelerator you're OK, but you can't get into nor out of Snoqualmie without some steep and long grades. His fuel savings soon cost a piston, but that was state of the art back in the 1970's, today we have much better engineering with fuel injection so that isn't likely to happen but the cost of the technology is rather large compared to a Fisher carburetor.