Re: Under Drive Pulleys..and the problems they cause.
 

It doesnt make that big a difference. The further away from the flywheel the worse the harmonics get. That's why the damper is critical at the far end of the engine. The real problems come from the furtherst crank throws.

If you are tempting fate by running over 6500 RPM with a small damper, you may not want to press your luck with a lighter flywheel too.

Re: Under Drive Pulleys..and the problems they cause.
 

i'm not sure what to think about this one anymore. i am a firm believer in the crankshaft harmonics causing serious issues with oil pump gears and main bearings being left to absorb all the excessive vibration. i have even discussed it with many whom i consider to be top in the Modular Motor world. I have even seen and experienced a few that have no problems and then change to a smaller balancer and or lighter flywheel and all of a sudden oil pump gear failure or BADY worn main bearings. now, for passing on my experience to others, i have been slammed on the inter web thingy by some whom i consider knowledgable and i respect very much.....i was recently called "an internet bench racer" over the whole **** thing....LOLOL...while i may find it funny now, believe you and me, i was ILL when it happened and have since lost quite a bit of respect for this person!!
so, what do i know with 25+ years of being an auto mechanic...20 of which being a master tech???? and the experience of a couple hundred or so mod motors i have been through or have built over the years. all i wish is to know FOR SURE if this is a problem or not!!!!!!!
not that i am impervious to failure myself but i have been spinning a stock short block Mach to 7500 rpms for years with 6500+rpm launches, just about every time at the track, with a Fluidampner and stock flywheel. now recently i have been debating a lighter flywheel change and am not sure if the luck i have pushed for years will finally catch up and go BOOM!!!! i just wish the info i once thought was accurate on the subject be definitively prove yeh or neh once and for all.
just running some thoughts past ya'all....

Re: Under Drive Pulleys..and the problems they cause.
 

Fluid damper is not a typical small diameter damper. The fluid is supposed to compensate for the smaller size. I dont know that much about them but I've never heard of a failure with one. What other modifications have you done to your engine? What kind of power is it making?

Re: Under Drive Pulleys..and the problems they cause.
 

Just for reference, the company "Fluidampr" makes two differnt diamater dampeners: http://www.fluidampr.com/FORD.htm, 7.5" and 6.5"

March's fluid dampener comes in only one diameter, I believe it's 6.25".

The stock Ford 4.6 dampeners are just under 7" in diameter and have various weights.

5.8lbs for NPI 2vs
6.5lbs for cobras and marks 8s
8.95lbs for PI 2vs
9.9lbs for marauders, mach 1 automatics and aviators

Note how the cast iron crank 4vs and the PI 2vs have a heavier dampener than the 4v engines with the forged cranks.

Re: Under Drive Pulleys..and the problems they cause.
 

not a lot done...just....
p&p heads
custom short runner ported intake
stg 3 crowers
long tubes
nitrous
and a ton of supporting mods...

i know the fluidampner that i have is stock size...i made sure. my stock balancer came apart on a launch a few years ago. but with my stock flywheel and fluid filled dampner i am wondering if i will be pushing my luck with an aluminum flywheel...or if all the harmonics issues will even come into play. my experience tells me to stay how i am....i do know that @ about 7000rpms the harmonics almost double and get worse over that rpm.
i don't know what to think anymore...LOL...just passing the subject around with ya'all to see what you think.

Re: Under Drive Pulleys..and the problems they cause.
 

Well, nobody knows exactly when you cross that line, especially since production tollerances and many other factors can change where that line is. For what it's worth, even ATI and Innovators West offer small size dampers for modular engines but the tech guy at ATI told me in no uncertain terms that the DOHC Ford should NOT be running the smaller diameter unit they offered. If you've ever held an ATI in your hand you find his statemen hard to believe. They look like they could dampen an elephant.

The small dampers from ATI and IW were produced with the lower reving, SOHC engine in mind. Just because a company makes a small damper for our cars, it doesnt mean we should use it. Problems usually come from secondary marketers who buy direct from the manufacturer and lack the knowledge or desire to sell you the right product. Most companies would be happy to sell you the small damper for your DOHC. ATI direct wont do it.

Re: Under Drive Pulleys..and the problems they cause.
 

LOL...i won't throw anyone under the bus, but they are on this forum...LOL...it is no big deal now...i just wish i wouldn't have been grouped or stereo typed like that...LOL...guess in the end it did bother me quite a bit because i see so many internet bench racers all the time. when i myself am not one to just post my butt off and i mostly TRY to keep to myself and help when i feel i can.

Re: Under Drive Pulleys..and the problems they cause.
 

LOL...NO definately not...LOLOL...i'm in san diego all the time, i woulda paid him a visit...LOLOLOL

i just now talked with and straightened everything out with the person after they read this. it was something that happened on svtp...LOLOL...yeah i know, i need to stay off of there....but the good news is, it seems it was a misunderstanding and the post was directed toward others and i took it the wrong way because it was under what i had posted and about the subject we were all speaking of....AWESOME news is the person apologized and me, being HUGE on respect, I VERY MUCH value the apology!!

Re: Under Drive Pulleys..and the problems they cause.
 

sorry i'm taking to long to post...i'm playing x box with my kids and posting here....LOLOLOL

Re: Under Drive Pulleys..and the problems they cause.
 

Interesting. There are a number of engineering elements that come into play. I thought this was an interesting statement from veteran motor head Gene Berg:

"The job of the flywheel is to smooth out firing pulses, stop vibration harmonics, and torsional twist. The most economical way for the factory to do this was to use a heavy flywheel. We ran tests for years on lightening flywheels with stock engines and found that indeed VW knew what they were doing to make the engine live a normal life with the stock crankshaft."



People only here what they want to hear!


Dang, sounds like a mean combo. Do I have you on my HP List on Corral? Sorry if I forget. If not, can you provide some SAE Dynojet numbers?


That's good news. Glad you got it resolved.

Re: Under Drive Pulleys..and the problems they cause.
 

Jerks in every group, don't worry about them. I appreciate you spreading your knowledge! :worship:

Re: Under Drive Pulleys..and the problems they cause.
 

Back years ago on the first page of this thread it says automatics suffer less vibration. So am I good to go with underdrive pullies? I'll never mod my car more than CAI and gears. I'd like to add the pullies.

Re: Under Drive Pulleys..and the problems they cause.
 

I've had them on my auto for 10K miles and no problems. I race the car hard and rev to 6000 rpm all the time.

Re: Under Drive Pulleys..and the problems they cause.
 

The actual under drive pulley's for the accessories are fine for any combo but if you're considering the smaller damper I'd keep it under 6500 RPM and it should be fine. You might have better luck with the fluid filled unit over the others.

Re: Under Drive Pulleys..and the problems they cause.
 

how does the power come on?? is it the more spin the motor the more it adds? do you have the dyno graph?

Re: Under Drive Pulleys..and the problems they cause.
 

So much speculation. Does anybody know any engines that failed right after the pulleys were put on? My bud's '91 5.0 had the pulleys on for years and the oil pump seized at about 110K miles. We tore the motor down and replace the pump and it ran decent but never as good as before. I'm sure the oil starvation hurt the motor some. I had a '95 5.0 with pulleys from 50K miles 'til 102K miles, no problems. I had a '99 GT with pulleys from 55K miles 'til 98K miles, no problems. My Mach got them at 45K miles has 67K miles now no problems. I raced the piss out of all these cars and went to redline and beyond many times.

Re: Under Drive Pulleys..and the problems they cause.
 

The pushrod and modular engines are both Mustang engines with underdrive pulleys and crappy oil pumps. I just thought I would share about it along with my experiences of the modular motors.

Re: Under Drive Pulleys..and the problems they cause.
 

What are you the Mach 1 police? What did I say that was not factual? Don't tell me what to post. You have a serious attitude problem, do you do this to people in real life? If you did you would get in lots of physical fights. You need to chill out and go get laid or something. :ORANGE:

Re: Under Drive Pulleys..and the problems they cause.
 

http://www.summitracing.com/parts/SUM-C2511/

I have this set on my '03 automatic. No problems from 45K to 67K miles with lots of hard racing and revving to and over redline. Do you guys think this set will cause the oil pump failure?

Re: Under Drive Pulleys..and the problems they cause.
 

Bill is just echoing the frustration the rest of us feel when someone with a clear lack of education on this subject contradicts widely understood information. You add further insult to injury when you refer to the opinion of every top modular engine builder in the country as "speculation". Bill just has a "unique" approach.