soundengineer

iTrader: (16)

also, as far as lasting longer....
it is a well known fact that the better you control vibration and harmonics the longer a part lasts...period.....
so the more control you have, the longer pieces will last...
which means the potential for your engine to last longer....after all...its only going to last as long as the first piece that fails.

DANOZ28

iTrader: (1)

while i understand that being critical in a drag racing engine is it really that critical for a street car that rarely sees over 6k rpm? thank you.

soundengineer

iTrader: (16)

all of it is technically "Critical"...but its the level of how critical that you have to personally weigh out...

if a part fails, your engine stops running...so yes...its critical.
however...if it can be replaced with no ill damage or stress to your engine...then yes...its far less critical..

if your springs fail, you could drop a valve, destroy a piston, even destroy the block....its a lot of money out of pocket to replace...
lots of people talk about that and for that reason everybody says to not go cheap on valvesprings...

nobody talks about the Crank balancer because its usually not thought of as part of the problems...
your crank damper is made to control vibrations... it takes mass to control that.

there are two ways to create vibration control...physical mass, or simulated mass(absorption)
the amount of vibration control does not change at lower rpms...but the stress caused by those vibrations goes up with RPM....
so the more the vibration, and the higher the RPM, the more control you need

will you have issues with the SLP underdrive.... probably not....most people dont notice any perceivable problems from their Underdrive pulley...

however..most people dont think long term either...
stock engines have been known to make it to 300,000 miles with no issues as long as there is regular maintainence.... will yours make it that long?...nobody knows until you get there.
will an ATI pulley allow it to get there.... I feel theres a better chance of it due to better control...




is it worth the cost?
well... you are going to drop over $1000 on a cam/springs/pushrods......
how about the $1500 most people spend on a set of heads?
what about the exhaust??? probably another $1000 if you go with a nice set of stainless headers?
catback??? X-pipe? more money.....

most people probably spend close to $5000 on their "Daily Driver with full bolt ons and a set of heads"
why not protect your investment by spending another $500 on a a good Harmonic Damper.




as far as what I spent......
I have probably spent a lot more than most people will...
my short block alone was $7000.....I've probably got close to $20k in my motor and motor accessories....
I would wager to say I'm a good 40k into my racecar project total including the chassis...I also have many years invested in it..this wasnt spent all at once...its been well spread out over many years...
so yes... I'm gong to buy an ATI damper to protect part of my investment..

DANOZ28

iTrader: (1)

i thank you for your explanation, my point is that in your opinion this ATI part may be the very best money can buy based on your experience & your drag racing buddies. i dont think your qualified to say / imply everybody elses stuff is junk.

soundengineer

iTrader: (16)

I'm pretty sure I did not call any body else's stuff junk....
I said the ATI was the best out of all of them and its trusted by the NHRA.

And I said an slp underdrive was failing to keep up with the vibration dampening on my motor which far exceeds 500 hp and far exceeds 6200 stock ls1 rpm Rev limiters...

soundengineer

iTrader: (16)

Also... to prove a point...
Single spring vs double spring..
Application dependent of course....
But I would not say a lesser single spring is junk....but a double spring is typically a vast improvement over a single and is usually preferred when buget allows.
Double springs control the valvetrain better than a single...
The ATI damper will control the crank harmonics better than the SLP underdrive will.

DANOZ28

iTrader: (1)

this is good info, wish i read this awhile back the last ? i'd like to pick your brain is what condition was your SLP pulley in when it failed, brand new? used 100 passes? how old? thx

soundengineer

iTrader: (16)

Bought new for the stock engine....
Installed on the 408 after approximately 12,000 miles of use

I don't think it failed....
It just wasn't up to the task of a 700hp engine spinning to 7500-8000 rpms

DANOZ28

iTrader: (1)

kinda funny we were just discussing this and last weekend horsepower tv was building a n/a engine with edelbrock LS-R heads that dynoed 785 fwhp. they used an ATI super damper! i think S.A.M. was building the motor?

2nd Gen Fl 'bird

iTrader: (13)

I have a March UD pulley which is a little bit heavier(mass) than stock. What's your take on this piece? Under drive but, not light either. Is it a diameter thing on controlling harmonics? Part not installed or ever ran to question it myself. Just curious about the previous comments.

mrvedit

Great thread! Glad I read it BEFORE buying a damper.
I was going ATI, but was considering a 10% underdrive. Not any more.

However, since I don't have A/C, I was considering #917302, which is half-way in weight (6.75 lbs) between the 917242 (9.75 lbs) and the UD units (4.5 lbs). I have an LS2 with a 231/239 cam and other mods that easily runs to 7000 rpm.

So, is that big and heavy enough and I should still get the 917242?

Also, since the LS2 is swapped into an '81 Camaro and I am switching to the Hooker brackets, I can just as easily go with Y-body (Corvette) spacing.

Thanks.

Burken01

iTrader: (88)

917242 is the full steel version, that's the one I have and was recommended by ATI, Kurt urban, and everyone else on yellowbullet when I was bugging them with questions..

The aluminum hub version was not recommended since ill be daily driving it.

mrvedit

The #917302 I am considering is steel hub with aluminum pulley.
Burken01: I assume what you meant is that the aluminum pulley is not suitable for a DD because the belt will quickly wear it out. I forgot about that - so thanks for the reminder.

Burken01

iTrader: (88)

I don't know about the belt wearing out quicker, but you want a steel hub if daily driving..

Aluminum hub will heat up too much if your daily driving it..

mrvedit

I meant that the aluminum pulley would wear out quickly.
BTW - You keep saying "hub" when you mean body or pulley; the inner hub which mounts on the crank is nearly always steel.
Thanks, you are helping with my decision.

Burken01

iTrader: (88)

ATI has aluminum hubs with aluminum outer pulleys, steel hub with aluminum outer, and steel hub with steel pulley..

I should have clarified, you want the steel/steel version for street use.

I called ATI about the steel hub/ aluminum outer vs the steel/steel and he said they are both fine to use.. I just wanted the heavier one..

But now that you mention it the aluminum pulley might possibly wear out quicker, but I have no direct experience with that..

GTO3DEUCES

Hiya,
As you’re very knowledgeable, what’s the basic premise of underdrive balancers ?

Is it that it’s taking stress off the accessory system ?

OR

It’s allowing the crankshaft to spin faster ?

All The Best,
Dave - GTO3DEUCES

big hammer

both

25% ATI makes a noticeable difference. The SLP is ok but it’s freaking heavy. The ATI is a lot lighter