Summit 25% under drive pulley.
09-18-2017, 09:57 PM
#1
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Summit 25% under drive pulley. help me decide if I should buy it or not. Car has long tubes, lid. 85mm MAF 85mm throttle body, ported ls6 intake ms3 cam and Stock heads. some people say yes some say no. I'm just wanting the most out of my set up as it is a "max effort cam" and if there's anything else you would recommend doing let me know.
09-18-2017, 10:12 PM
#2
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Your power steering will weaken (less fluid volume), your alternator might not charge nearly as well at idle(75% of normal amperage) and your A/C will not be as cold. PLUS, your water pump will not cool as well either. Is all that worth gaining a few HP? The cam will still help your engine put out "max effort".
09-19-2017, 07:58 AM
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^^^^what a dumb post 
Go for it OP, I ran one for years and years without any issues. Not to mention, with aftermarket cams your idle is RAISED, so your accs are actually spinning at stock idle speeds, but when it revs they accelerate slower, which you will notice!
Go for it OP, I ran one for years and years without any issues. Not to mention, with aftermarket cams your idle is RAISED, so your accs are actually spinning at stock idle speeds, but when it revs they accelerate slower, which you will notice!
09-19-2017, 10:58 AM
#4
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I can accept your insult, though your premise that the idle is raised, negating the decreased flows from the accessories, does not always apply. Many using the pulley do NOT have a cam that necessitates a higher idle. THOSE users WILL see effects of decreased accessory function. SO if you think my post is still dumb, you are a victim of your own narrow-minded thinking.
09-19-2017, 12:21 PM
#6
TECH Senior Member
I read what HE has, but was speaking for other situations. For THIS situation, yes, it would function as you say. Sorry for over-generalizing.
09-19-2017, 06:02 PM
#7
You were both right and you both generalized. I've noticed he's just a massive dick head to everyone. Just ignore it. The dump post **** was uncalled for just because his car didn't have the issue doesn't mean everyone's experience will be the same.
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09-19-2017, 06:18 PM
#8
TECH Senior Member
Thank you 00pooterSS! You try to do what would be helpful, but yeah, what you said!
09-20-2017, 11:42 AM
#9
To the OP under drive pulleys do offer small gains, but there are several trade offs. I don't like them personally because in the Honda world the light pulley doesn't soak up the harmonic vibrations and many people have had oil pumps shatter. Happened to a buddy of mine recently with his high dollar forged motor turbo supra. A couple hundred dollar pulley nearly wrecked his big dollar motor. They factory style pulleys are called harmonic balancers/dampers because they absorb harmonic vibrations in the crank shaft. They are able to do that because of their weight, remove the weight and you remove the harmonic balancing/dampening capability and increase harmonics in the crankshaft.
Not worth it in my opinion. But it's your car, not mine.
09-20-2017, 03:16 PM
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tberg725 (10-13-2020)
09-20-2017, 05:39 PM
#11
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I doubt you hurt any feelings, because I really don't give a rat's ***. I just put out here what I know. And what I know usually "holds water"
09-20-2017, 05:40 PM
#12
I bet, you'd be hard pressed to find anyone with SOLID issues due to running an underdrive pulley that was NOT related to some other underlying cause. That plus during our platform years, 98-02, very very little changed. All accs could be swapped from year to year with likely the exact same specifications. So, they either cause issues or they dont, it's not like some magical car can run one fine and another it's complete chaos because the car can't deal with it. Gimme a break. It was a dumb **** post, and if I'm a dick head cause I called it out so ******* be it. I can't help it you wear your feelings on your shoulders.
I agree, when you have an underdrive pulley on the crank, you need the overdrive pulley on the alternator. I ran mine without the overdrive pulley for about a year, then the battery died while I was idling in line at the track. Some bozo had dropped his tranny on the track so we had to wait a long time. I installed the overdrive pulley, and no issues whatsoever since then (5+ years).
Last edited by 00pooterSS; 09-20-2017 at 05:52 PM.
09-20-2017, 05:45 PM
#13
I've had friends that this happened to and finding others with the problem also took seconds just now. Here's one example
Skip Cannon
15th March 2006, 01:51
A few years ago, quite a few people blew up oil pumps (and engines) - and almost all of those were running an underdrive crank pulley, like Unorthodox Racing, on a boosted engine. Speculation is that the UR underdrive lightweight crank pulleys do not include a critical harmonic damper element, and allow dangerous harmonic vibrations be transmitted to the oil pump drive, which eventually (sooner rather than later) shatters.
By any chance, were you running an aftermarket crank pulley on your boosted engine?
I think I was the first to have an oil pump shatter. There were at least 8 of us who experienced the problem. All had undampened underdrive crank pulleys and high horsepower turbo engines. It seemed to take about 2,000 miles from installation of the pulley to trashing the engine. By the time we figured it out, I was nearly 2,000 miles into a new engine, still using the underdrive pulley. I pulled the engine and inspected the oil pump. There were marks on the lobes of the G-rotor oil pump. I figured I caught it just in time.
Someone I knew inside of Mazda searched the computer records and could not find any recorded oil pump failures on any Miatas. The only oil related failure in the system at that time was from running the engine out of oil.
Prior to purchasing the pulley, Unorthodox Racing had assured me there would be no problem going from the factory pulley/harmonic dampener to their underdrive pulley without provision for harmonic dampening. They were wrong but when presented with the facts, denied the pulley was responsible, refused to take any responsibility and wouldn't even refund the price of the pulley. Some of us looked into the possibility of a class action suit but determined the company didn't have the resources to pay any judgement.
As far as the engine that is the subject of this thread, what were the symptoms of the failure? Did oil pressure go to zero, where there any unusual noises prior to complete failure?
When my engine blew at the track, it was at about 6,500 rpm and off the throttle at turn in to a series of S bends. When I fed it throttle at the apex, there was a noticable lack of power and a sound similar to an old British 4 banger with badly synchronized twin SU carbs being reved up. I looked at the oil pressure gage and it read zero so I shut off the ignition and coasted to a stop. By that time, the engine was toast.
Skip
Skip Cannon
15th March 2006, 01:51
A few years ago, quite a few people blew up oil pumps (and engines) - and almost all of those were running an underdrive crank pulley, like Unorthodox Racing, on a boosted engine. Speculation is that the UR underdrive lightweight crank pulleys do not include a critical harmonic damper element, and allow dangerous harmonic vibrations be transmitted to the oil pump drive, which eventually (sooner rather than later) shatters.
By any chance, were you running an aftermarket crank pulley on your boosted engine?
I think I was the first to have an oil pump shatter. There were at least 8 of us who experienced the problem. All had undampened underdrive crank pulleys and high horsepower turbo engines. It seemed to take about 2,000 miles from installation of the pulley to trashing the engine. By the time we figured it out, I was nearly 2,000 miles into a new engine, still using the underdrive pulley. I pulled the engine and inspected the oil pump. There were marks on the lobes of the G-rotor oil pump. I figured I caught it just in time.
Someone I knew inside of Mazda searched the computer records and could not find any recorded oil pump failures on any Miatas. The only oil related failure in the system at that time was from running the engine out of oil.
Prior to purchasing the pulley, Unorthodox Racing had assured me there would be no problem going from the factory pulley/harmonic dampener to their underdrive pulley without provision for harmonic dampening. They were wrong but when presented with the facts, denied the pulley was responsible, refused to take any responsibility and wouldn't even refund the price of the pulley. Some of us looked into the possibility of a class action suit but determined the company didn't have the resources to pay any judgement.
As far as the engine that is the subject of this thread, what were the symptoms of the failure? Did oil pressure go to zero, where there any unusual noises prior to complete failure?
When my engine blew at the track, it was at about 6,500 rpm and off the throttle at turn in to a series of S bends. When I fed it throttle at the apex, there was a noticable lack of power and a sound similar to an old British 4 banger with badly synchronized twin SU carbs being reved up. I looked at the oil pressure gage and it read zero so I shut off the ignition and coasted to a stop. By that time, the engine was toast.
Skip
09-20-2017, 05:48 PM
#14
Thought you said this would be hard. Taken from another forum
dont do pullies. i did them, and was disappointed with the results, to put it nicely. lights were dim at a stop light, everything just about died. i only run a cd player head unit on stock speakers, so if your runnin an amp/sub or two, you will definately have problems. then to top it off, my car ran hotter, not much, but hotter to say the least. i did not notice any performance at all. dont waste your money, trust me. save it for something else, or like you said, get those sub frame connectors. thats probably one of the best mods to do. wont notice anything probably but your chasis will thank you...if it could talk....or something.
dont do pullies. i did them, and was disappointed with the results, to put it nicely. lights were dim at a stop light, everything just about died. i only run a cd player head unit on stock speakers, so if your runnin an amp/sub or two, you will definately have problems. then to top it off, my car ran hotter, not much, but hotter to say the least. i did not notice any performance at all. dont waste your money, trust me. save it for something else, or like you said, get those sub frame connectors. thats probably one of the best mods to do. wont notice anything probably but your chasis will thank you...if it could talk....or something.
09-20-2017, 05:50 PM
#15
He's just one of those guys that gets loud behind a keyboard apparently. I keep the feelings out of it online, I prefer getting loud in person.
09-20-2017, 10:07 PM
#16
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Well I got called the ******** so I figured you got your panties in a wad. I didn't read your bullshit, but I can say that if you throw some bullshit unbalanced pulley on the front of your engine yeah it could cause issues. But that has nothing to do with the accs being driven slower....it's because your motor is balanced and this China crap isnt. I personally had good luck with slp/powerboat so that's all I can speak for. His post was still BS, amazing after I posted that I get PMs saying that guy is an idiot. Just saying.
Rent free.
Rent free.
09-20-2017, 10:11 PM
#17
09-21-2017, 11:37 AM
#19
TECH Senior Member
Sounds like there's 2 topics interwoven here:
- pulley being undersized,
- pulley not being constructed as a harmonic damper.
The second one causes much more devastating problems.
- pulley being undersized,
- pulley not being constructed as a harmonic damper.
The second one causes much more devastating problems.
09-21-2017, 01:25 PM
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i have the summit 25% UD pulley. i was worried about dim lights so i added the OD alt pulley. negative is balancer doesnt have a key slot to lineup timing marks (i thought that was odd) seems to work fine however since i added a torque convertor i get some belt squeek it revs up & down so fast. maybe air belt but both belts have stayed on car. you decide. cheers!