Underdrive Pulley Bashing.

dmontzsta · Aug 1, 2006

I have seen alot of threads talking about pulleys being a waste. But, they are known to make 5hp/5tq gains, which is pretty common. So I just wanted to start a thread up again and get some real opinions, on why they are so bad? 5hp/5tq to me, seems pretty good, you really want all you can get. You can pick up a set of pulleys for $75-$150 new or used. That is a pretty cheap bolt on really. Alot of guys in the import world spend big bucks on full exhaust systems, that will not even net as much as 5hp/5tq. What are your thoughts?

Here is an old write up 5.0 Magazine did.
http://www.mustang50magazine.com/techarticles/33479/index4.html

The other reason I wanted to do this thread, is because I am thinking of picking some up, but just wanted to revisit it for the 1 millionth time!

Kilgore Trout · Aug 1, 2006

What is up with that 75 circle racer? Got pics?

01Steeda · Aug 1, 2006

I never had any issues with my steeda's.. but they were put on proffesionally. Only problem I had was I forgot to tell my tuner about them and they cut 6lbs of boost out of it when he put the blower on

dmontzsta · Aug 1, 2006

01Steeda said:
I never had any issues with my steeda's.. but they were put on proffesionally. Only problem I had was I forgot to tell my tuner about them and they cut 6lbs of boost out of it when he put the blower on

Thats another thing, people say you cant use them if you go S/C. I say, why not? you just get the right size belt to compensate for them.

dmontzsta · Aug 1, 2006

Kilgore Trout said:
What is up with that 75 circle racer? Got pics?

Here you go...

OT: But I am building a 650+hp 429 right now. It will use Super Cobra Jet heads, with a offy T-ram (SCJ ports) dome tops, nice big cam and two Holley 750s. Should do around 110mph and hit single pin turns at 65mph. They pull so many Gs in a turn, that you have to hold on for your life, it is undescribable.

CobraRed_96_GT · Aug 1, 2006

I like mine fine, feels more responsive to the pedal and it revs up a lil faster. I put em on myself just need to bake the crank pulley and use a harmonic balencer

rebelleader · Aug 1, 2006

dmontzsta said:
Thats another thing, people say you cant use them if you go S/C. I say, why not? you just get the right size belt to compensate for them.

The size of the belt is not the issue, the diameter of the pully is why it is not good for a s/c application. The U/D pullies will spin the s/c slower, thus producing less boost. Less boost yields less power.

01Steeda · Aug 2, 2006

rebelleader said:
The size of the belt is not the issue, the diameter of the pully is why it is not good for a s/c application. The U/D pullies will spin the s/c slower, thus producing less boost. Less boost yields less power.

exactly.. belt size is irrelevant as the same belt works... it is the ratio of pulley sizes. the crank pulley on an underdrive set is about a half inch smaller.. thus causing the blower pulley to turn slower.... less boost.

and no you cant run a smaller blower pulley to compensate.. to much of a ratio to make up.

svtpower · Aug 2, 2006

oil pump gears failure

Underdrive pulleys have been linked to many late model (99+ especially) oil pump failures because of the oil pump gears shattering. The stock crank pulley is best for high rpms unless you have strong aftermarket oil pump gears. I have zero first hand experience with this, but I have read several posts about it over the years.

In short 5hp is not worth putting an internal component like that at risk. That along with people breaking off the crank pulley bolt head. To me its just not worth it

san~man · Aug 2, 2006

svtpower said:
Underdrive pulleys have been linked to many late model (99+ especially) oil pump failures because of the oil pump gears shattering. The stock crank pulley is best for high rpms unless you have strong aftermarket oil pump gears. I have zero first hand experience with this, but I have read several posts about it over the years.

In short 5hp is not worth putting an internal component like that at risk. That along with people breaking off the crank pulley bolt head. To me its just not worth it

I don't believe I've ever read of that happening personally. But, I've had mine on for about 4 years with zero problems.

stangGT97 · Aug 2, 2006

san~man said:
I don't believe I've ever read of that happening personally. But, I've had mine on for about 4 years with zero problems.

There was actually a thread not so long ago in which this was brought up. I guess the majority of people having issues with bad balancers causing component failures were guys w/ built motors spinning them to 7000+. That would also make this a bit of an issue for the DOHC guys who can easily rev their motors that high. I don't have UDPs but when I first entered the mustang scene, it seemed like that was a hot item to have on your car so I don't know what happened.

JOHNS01GT · Aug 2, 2006

But think about the fact that they are cheap and easy hp/tq and a lot of mustang owners have them. Of course every now and then you will hear a horror story, but the majority, and I mean majority have no problems whatsoever. 2 years with mine with many 6000 rpm powershifts...0 problems.

RandyStinchcomb · Aug 2, 2006

svtpower said:
Underdrive pulleys have been linked to many late model (99+ especially) oil pump failures because of the oil pump gears shattering. The stock crank pulley is best for high rpms unless you have strong aftermarket oil pump gears. I have zero first hand experience with this, but I have read several posts about it over the years.

In short 5hp is not worth putting an internal component like that at risk. That along with people breaking off the crank pulley bolt head. To me its just not worth it

on the above problem, from what I've seen, was due to people putting the damper and bolt back on wth an air impact gun.

BooWFO · Aug 2, 2006

if you can get them at a price you consider resonable. They are a nice helping mod. However they do make the ac less effective, causing you to run it at max more and thereby lowering mpg on the highway in the summer.
Now personally I only like the 1peice models, and they are rather pricey for a 5hp increase at best. I picked mine up used for less than half the cost of new.

stangGT97 · Aug 2, 2006

BooWFO said:
if you can get them at a price you consider resonable. They are a nice helping mod. However they do make the ac less effective, causing you to run it at max more and thereby lowering mpg on the highway in the summer.
Now personally I only like the 1peice models, and they are rather pricey for a 5hp increase at best. I picked mine up used for less than half the cost of new.

could you name specific brands that produce a 1 piece model?

jstreet0204 · Aug 2, 2006

svtpower said:
Underdrive pulleys have been linked to many late model (99+ especially) oil pump failures because of the oil pump gears shattering. The stock crank pulley is best for high rpms unless you have strong aftermarket oil pump gears. I have zero first hand experience with this, but I have read several posts about it over the years.

In short 5hp is not worth putting an internal component like that at risk. That along with people breaking off the crank pulley bolt head. To me its just not worth it

This is an issue with the aluminum block 4v's spinning 7000+rpm. I have yet to see this issue with a 2v iron block.

[Twitch] · Aug 2, 2006

BooWFO said:
if you can get them at a price you consider resonable. They are a nice helping mod. However they do make the ac less effective, causing you to run it at max more and thereby lowering mpg on the highway in the summer.
Now personally I only like the 1peice models, and they are rather pricey for a 5hp increase at best. I picked mine up used for less than half the cost of new.

I have Steed UD pulleys and the AC is as cold as ever, I actually had to lower it because it was getting too cold. Yestereday, it was 115F here and it worked perfectly, on the "AC" setting, not the "Max AC".

myponyrocks · Aug 2, 2006

I abuse my car, and have had Steeda UDPs on for 48k miles... no issues. PERIOD.

SilverBullet00 · Aug 2, 2006

RandyStinchcomb said:
on the above problem, from what I've seen, was due to people putting the damper and bolt back on wth an air impact gun.

IS this damaging becuase of over torquing the bolt then? In my shop manual it says to use a impact gun?

And I thought you were suppose to run at MAX AC for the best temp and efficiency? Am I backwards?

svtpower · Aug 2, 2006

may be right

You may be correct that it is only an issue on the 4V crowd. I will say that on my 5.0 they made a VERY NOTICABLE power increase and seat of the pants said money well spent. On my 99GT I had the Steeda ones and I honestly could not feel the difference. That and the belt never stopped squealing after they were installed. I tried 2 different belts and checked the tension several times. The crank bolt was properly torqued with a torque wrench. Who knows...on the Cobra I decided against them.

Honestly if you want a good seat of the pants boost get a timing adjuster or better yet a Predator or Xcal2 or something like that. The most noticable mod power wise I did on my 99 GT was the Predator, using it on my Cobra with a custom tune and very happy with it.

Underdrive Pulley Bashing.

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