Dyno results Underdrive pulleys

mustangsquared · Jan 11, 2007

I believe all the stangs from 95 forward had a 130 amp alt.... I still need to add my UD's.... havent had the time to do it.

MBDiagMan · Jan 11, 2007

The slower alternator speed will only present a problem if you spend A LOT of time with the engine idling such as LOTS of stop and go traffic. The alternator output is regulated and the energy is stored in a battery. As long as the alternator gets some time at speed, there will be no alternator output problems.

Good luck,

05canuck · Jan 11, 2007

I have the pullies and have had no effects whats so ever on the alt , I run the shaker 500 with a custom built sub box 2-10's and a 500 watt amp. I have run it in the summer with the ac on and in the fall with the heater on and nothing. As long as you don't go pass your cars alt ability which is the case with the stock as well you'll be fine. BTW I work for Ford and did ask a tech before I did this and the respnse was the same, hope this helps Mark

'69Stang · Jan 11, 2007

I've read, and been told, that 80%+ of all the RWHP gains from U/D pulleys comes from the lighter weight of the after-market aluminum pullies versus the steel OEM pullies. Lower weight of the recipricating assembly always frees uo horsepower. It therefore might make sense to run stock aluminum sized pulleys, unless the stock ones are now aluminum (which I doubt).

khendrix2374 · Jan 11, 2007

There are ZERO negative effects running under drive pullies on these cars... Unless you change the size of the alternator pully, there will be ZERO negative effects. Period!

mustangsquared · Jan 12, 2007

'69Stang said:
I've read, and been told, that 80%+ of all the RWHP gains from U/D pulleys comes from the lighter weight of the after-market aluminum pullies versus the steel OEM pullies. Lower weight of the recipricating assembly always frees uo horsepower. It therefore might make sense to run stock aluminum sized pulleys, unless the stock ones are now aluminum (which I doubt).

If that were the case then the best mod would be to replace the drive shaft since it weighs in at approxiamtely 50lbs.... and the aftermarket ones weigh in at 20 lbs... by slowing the waterpump down there is less resistance on the water pump propeler since it is not pushing as much water in the same time frame/RPM which is what free's up the power... every pulley under the hood turns something that has a set minimum resistance.... slow the pulley down and it reduces the HP used by the engine to turn that pulley. Think of it as starting out in 3rd gear (stock pulley's) and then trying again in 1st gear (UD's)...

red05bullitgt · Jan 14, 2007

Thanks for all your replies and input guys, I'm very grateful...I'll either be going with the Steeda or Roush pulleys..

bigcat · Jan 14, 2007

red05bullitgt said:
Thanks for all your replies and input guys, I'm very grateful...I'll either be going with the Steeda or Roush pulleys..

both are good choices. remember, the roush cuts a stud on the alternator bracket, while steeda replaces the stud with a bolt.

i have a write up for the roush, but its on the back burner for now. we have a few other important things to work in in the mean time. if you want, i can email you the .doc, but you will have to wait for pics. up to you.

red05bullitgt · Jan 14, 2007

Sounds good Bigcat, I'll be looking forward to you're e-mail..

black93gthatch · Jan 18, 2007

isn't it true that you can just buy the crank pulley and the water pump pulley? and still get significant gains? that's what i'm tryin to get done tomorrow.. is buy those 2..

red05bullitgt · Jan 18, 2007

If you're referring to the current 05-07 Stang ? then YES...as far as I'm aware of ? both the Roush and Steeda pulleys are only available and require the use of the Water pump and Crank pulleys.. I believe that BBK also has the same setup.

8850 · Jan 18, 2007

black93gthatch said:
isn't it true that you can just buy the crank pulley and the water pump pulley? and still get significant gains? that's what i'm tryin to get done tomorrow.. is buy those 2..

You can buy just the crank pulley directly from ASP if you like. They manufacturer most of the underdrive pulleys for our distributors. They will give you the part number of the shorter belt required. The crank pulley does most of the job. The water pump pulley adds some additional gains but it is already slowed by 25% from the crank. Or if you order from one of our distributors tell them part number 526400.

red05bullitgt · Jan 18, 2007

No offense but I'll have to respectfully disagree...Both the crank and water pump pulleys combined reduce accessory drag by 25% in addition it's the water pump pulley that's considered as the power robbing thief..And you can ask Bigcat that question personally..

8850 · Jan 19, 2007

red05bullitgt said:
No offense but I'll have to respectfully disagree...Both the crank and water pump pulleys combined reduce accessory drag by 25% in addition it's the water pump pulley that's considered as the power robbing thief..And you can ask Bigcat that question personally..

Did you not read my post #26? You get additional reduction from the water pump pulley assuming it is larger than the factory. That's in addition to reduction produced by the crank. You don't have to install the water pump pulley to have reduction of the water pump.

red05bullitgt · Jan 21, 2007

No I didn't notice your post #26, I responded directly to your last one..But I can confirm that the Roush, Steeda and BBK water pump pulleys are larger than stock and I also like the concept of retaining the stock serpintine belt as well..

JTGrant · Jan 22, 2007

How about every one's take on the steeda pullies. I purchased a set but I have not installed them yet. How is the SOTP feeling?

Jimp · Jan 22, 2007

JTGrant said:
How about every one's take on the steeda pullies. I purchased a set but I have not installed them yet. How is the SOTP feeling?

To be honest I didn't really notice much of a difference. I'm sure it made a difference but after my other mods I really can't tell.

chad9350 · Jan 23, 2007

Use only the underdrive crank pulley..

dont use waterpump, eventually playing with fire... and dont use the alt. pulley... again, need a good charge...

a tip for getting around the alt.: use a alt. bypass on a toggle swith... turn off a idol... make run, turn on at idle

metroplex · Jan 23, 2007

In the end you must consider your application. I would recommend against underdrives for daily drivers or if you EVER plan to go with a supercharger in the future. If this car is a naturally aspirated dedicated race car, or if you desire the most power output possible and need to squeeze and every last pony, go for it. Chances are if you fall into this category, you are also running a 93 octane tune for daily driving.

tom281 · Jan 23, 2007

Use the Steeda pullies and forget about your worries.......... there is very little reason to worry about underdrives on these cars. Roush pullies are nice, Saleen pullies are too expensive, Steedas are SFI approved and are the best selling pullies on the market for these cars.

If you want to go one step further, buy only the crank pully and do an electric water pump.

Dyno results Underdrive pulleys

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start with the upper hole, and if more traction is

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