I am about to put on a new degree pulley and was wondering if I should get a stock pulley, or a power pulley. I have a stock 1600 am about to put new 88 P & C"s Noticable power or not?
Original Post
Replies sorted oldest to newest
I am about to put on a new degree pulley and was wondering if I should get a stock pulley, or a power pulley. I have a stock 1600 am about to put new 88 P & C"s Noticable power or not?
Check
You might not want to do that. The pulley is smaller in diameter and will run the fan belt at lower speed which will slow up the fan. This will make, in theory, more power...but...the fan will run slower and less cooling.
You might not want to do that. The pulley is smaller in diameter and will run the fan belt at lower speed which will slow up the fan. This will make, in theory, more power...but...the fan will run slower and less cooling.
Chuck,
There are some fair number of things to think about before running a power pulley. Most specifically your normal and peak oil temperature, your head temperature on the hottest day of the year being driven like you normally drive it, and are you using additional oil cooling such as an external cooler? Also, how hot is your engine compartment on the hottest day of the year....?
I have been running a power pulley for years on several different engines, all of which are significantly larger than 1600 cc's. But, I have always set the engines up with the most efficent fan housings and have always used guages and have measured head temps, oil temps, oil pressure, and so forth. In that fashion I am comfortable in saying that power pulleys have worked well for me. By the way, you can't make up for a lack of air flow with more oil cooling....don't want to confuse the issue. But also if you are pushing 225 or more degrees on oil temp and are using a doghouse cooler I would certainly never suggest a power pully was a good idea....
Also, timing of the engine as well as jetting of the carbs can make the engine run hotter or cooler also....so you need to consider those sorts of things too...the guages will tell you where you are, and the air temps, the air flow, the timing, and the jetting may be the "whys" of the temps you have.
To give you some ideas of how my engine behaves with a DTM fan shroud here are my temps last summer one day following a run down the road at speeds of 80 - 120 mph for more than a half hour....and I have a doghouse cooler as well as an external cooler with electric fan.
external temp 100 degrees (its Texas you know)
oil temps 190- 200 degrees F, 11 quart capacity dry sump.
head temp measured at the #1 spark plug 290-300 degrees F
under bonnet temperature 150 degrees (need to duct in more fresh air as well as wrap the headers with thermal tape etc)
Please keep in mind the most cost effective shroud is the early dog house style (see Jake Raby testing on his web site) and while the DTM from Jake is slightly better at cooling a new doghouse shroud is $50 +/- the DTM id $450 +/-.
you can see more than you may want at http://www.pbase.com/tmpusfugit/jims_550_photos&page=all
There are some fair number of things to think about before running a power pulley. Most specifically your normal and peak oil temperature, your head temperature on the hottest day of the year being driven like you normally drive it, and are you using additional oil cooling such as an external cooler? Also, how hot is your engine compartment on the hottest day of the year....?
I have been running a power pulley for years on several different engines, all of which are significantly larger than 1600 cc's. But, I have always set the engines up with the most efficent fan housings and have always used guages and have measured head temps, oil temps, oil pressure, and so forth. In that fashion I am comfortable in saying that power pulleys have worked well for me. By the way, you can't make up for a lack of air flow with more oil cooling....don't want to confuse the issue. But also if you are pushing 225 or more degrees on oil temp and are using a doghouse cooler I would certainly never suggest a power pully was a good idea....
Also, timing of the engine as well as jetting of the carbs can make the engine run hotter or cooler also....so you need to consider those sorts of things too...the guages will tell you where you are, and the air temps, the air flow, the timing, and the jetting may be the "whys" of the temps you have.
To give you some ideas of how my engine behaves with a DTM fan shroud here are my temps last summer one day following a run down the road at speeds of 80 - 120 mph for more than a half hour....and I have a doghouse cooler as well as an external cooler with electric fan.
external temp 100 degrees (its Texas you know)
oil temps 190- 200 degrees F, 11 quart capacity dry sump.
head temp measured at the #1 spark plug 290-300 degrees F
under bonnet temperature 150 degrees (need to duct in more fresh air as well as wrap the headers with thermal tape etc)
Please keep in mind the most cost effective shroud is the early dog house style (see Jake Raby testing on his web site) and while the DTM from Jake is slightly better at cooling a new doghouse shroud is $50 +/- the DTM id $450 +/-.
you can see more than you may want at http://www.pbase.com/tmpusfugit/jims_550_photos&page=all
Great post by Jim; add also compression ratio to the equation: the higher compression ratio the odds of your engine running hotter increase. Fiberglass Speedster replicas are notorious for not having sufficient fresh air flow into the engine compartment so we are always tinkering with our cars to improve cooling. Another trick that has been used quite a bit is installing a Porsche 356 pulley on your generator/alternator/fan which has a smaller diameter than a regular VW and therefore will turn the fan faster. Maybe combining a VW power pulley (same diameter as a stock Porsche 356 crank pulley) and a 356 pulley in the alternator/generator/fan will compensate for each other and work perfectly. Most of us here use a regular diameter VW crank pulley with the 356 pulley up top to optimize cooling for street cars. And as Jim has said I swapped my 36 hp style fan shroud (which looks cooler and more like a real 356 Porsche) for a '71-on OEM VW doghouse (which doesn't look as good but works a whole lot better)complete with the OEM thermostat and shutter system.