OEM pulley not good for big HP :( ... sad news

[upgradedsupra]

The engine is fine and will be up and running when I get my new ATI pulley but luckily I decided to take it off when I did.

Not many people run this much hp and let alone with the OEM pulley. I was planning to get an ATI pulley soon but have been putting it off. Well the time has come! After a few pulls on the freeway and some 32PSI pulls on a deserted road this past Saturday, I noticed the pulley had a little wiggle so in case of something that could go wrong, I decided to take it off. Well the bolt broke off. Yup! The hardened steel crank bolt (in the crank) Not a big deal as that is the easy part. The crank pulley welded to the crank and I have to simply grind it down which again is easy. (with a stone) The key is perfect (thank GOD) so I am ordering my custom ATI pulley tomorrow. When I spoke to them on the phone, they said I needed an 8" dampener (OEM is 5") and since the trigger wheel is also custom, it will be down for a little while.

Lesson learned from this? Now people SHOULD replace the OEM pulley with a proper one when getting up in the big hp range :biglaugh:

Thanks for helping out Dave

Duane

 

[Tun_x]

Don't scare me like that.. Hey Duane what ign coils are you using?

Jason

 

[kwnate]

Mine is fine and I have more power then you. But I will be upgrading mine as well. Was the bolt rusted in place?

 

[upgradedsupra]

Mine is fine and I have more power then you. But I will be upgrading mine as well. Was the bolt rusted in place?

How about drive yours first and see what happens..:icon_razz A whopping 19HP more! :aigo: (Until I get a clutch)

 

[IJ.]

Duane: LMAO @ "stock damper" I chickened out at 500 and till then had been running a brand new one

 

[upgradedsupra]

Duane: LMAO @ "stock damper" I chickened out at 500 and till then had been running a brand new one

You still running OEM? This was new

 

[IJ.]

I ran a new OEM till 500 then went ATI

 

[upgradedsupra]

I ran a new OEM till 500 then went ATI

The OEM from ATI is only good good for 400-500 max they said

Duane

 

[IJ.]

Ahhh I see what you mean now

Figgie has the larger one on his car but as I knew 500ish was my upper limit I just grabbed the Stock size one to compliment my Light Crank and the JE's in the new build.

 

[suprarich]

They have a newer oem size unit now rated for 600hp. I think they have a considerable safty margin on the ratings.

 

[Dirgle]

Maybe some one could enlighten me on the technical details as to why a dampener/pulley might have an established max HP rating? Such as with the ATI or even why the OEM one itself might fail at higher numbers?

 

[jt2ma71]

Damn! my ATI is only rated @ 800 and that is crank HP. I don't like taking things to the the limit so I will only be @ ~600+ at the wheels?
Duane glad you got it all sorted out, so everything was easy huh :naughty: :1zhelp:

 

[jt2ma71]

Maybe some one could enlighten me on the technical details as to why a dampener/pulley might have an established max HP rating? Such as with the ATI or even why the OEM one itself might fail at higher numbers?

maybe have something to do with harmonics absorption. I would also think that it should be rated by RPM alone but the vibration is much more intense at higher HP's.

That's why it helps to have everything balanced. When my motor was balanced, it was done with the flywheel and clutch assembly with the crank pulley to be used. Not to mention the bolts, although each piston and rod was weighed and balanced also and the crank was balanced by itself.

 

[ForcedTorque]

While we are enlightening, I have a question from what I have read here. Duane, you have used the stock damper for some time now at 800+, and several others have runn 500+ , and I have never heard of a lot of trouble. It has been stated that the ATI stock size damper was good for 400-500hp max. On this much info only, this leads me to believe that ATI may not even be up to the quality of stock. I know there's a good bit of ignorance in that statement, but I wouldn't mind a little discussion on that (I'll read quietly now).

 

[IJ.]

The ATI OEM size damper is half the weight of stock so this would explain the lower comparative rating.

I'm guessing the larger ATI is much closer to the stock weight and can absorb the harmonics much better at higher degrees of crank deflection.

 

[figgie]

They have a newer oem size unit now rated for 600hp. I think they have a considerable safty margin on the ratings.

No such thing

the only one the sell for the 7m that is stocked is good for 400hp-500hp at the crank SUSTAINED.

basically for every 100 above that requires 1 inch increase in diameter.

Ie for a sustained 800 hp at the crank requires a pulley with an 8 inch OD. ATI will tell you this right up front.

 

[figgie]

The ATI OEM size damper is half the weight of stock so this would explain the lower comparative rating.

I'm guessing the larger ATI is much closer to the stock weight and can absorb the harmonics much better at higher degrees of crank deflection.

well it has to do more with the elastometer sizing within the shell.

like my custom made one. Good to high 600 sustained. It can go higher but requires frequent inspection and rebuild at that point.

 

[IJ.]

Wayne: Thanks for the clarification

All these young hotshots with their hopped up racers

In my day..................

 

[figgie]

While we are enlightening, I have a question from what I have read here. Duane, you have used the stock damper for some time now at 800+, and several others have runn 500+ , and I have never heard of a lot of trouble. It has been stated that the ATI stock size damper was good for 400-500hp max. On this much info only, this leads me to believe that ATI may not even be up to the quality of stock. I know there's a good bit of ignorance in that statement, but I wouldn't mind a little discussion on that (I'll read quietly now).

actually just because the OEM worked does not mean it was actually doing its job. And on top of that the age of the running oem cramk pulley is basically making the rubber not doing ANY dampening whatso ever. Again the ATI hp rating is SUSTAINED.

IE like NASCAR... 800 HP SUSTAINED.

I would like to see the stock OEM damper hold up to 400 hp SUSTAINED for an hour and see what really happens. I myself would not bet a motor on that

 

[figgie]

Wayne: Thanks for the clarification

All these young hotshots with their hopped up racers

In my day..................

haha

"IJ: In my day we could run a barbeque pit in the car while I was driving down the road, cooking shrimp!!"