How fast on N/A crank and rods?

[Ted]

I know there is a difference between the turbo and N/A cranks and rods, but is it really a big deal?

How fast have people gone with the "wrong" parts so to speak?

Would this be safe for mid 11's?

TD

 

[frankg]

I used to go low 11's consistantly with a NA crank in the buildup below, never any problems. A local guy Banning goes 11.0-10.9 range with many trouble free passes on a NA crank also. I would run a NA crank again without thinking twice. Frank

 

[J Banning]

Originally posted by Ted
I know there is a difference between the turbo and N/A cranks and rods, but is it really a big deal?

How fast have people gone with the "wrong" parts so to speak?

Would this be safe for mid 11's?

TD

See times in my sig

It's all how you have the car tuned. I have over a dozzen 10 sec passes just this year, plus 2+ dozzen in the 11.30 & faster. I spin it up to 6,300rpm on the 2/3 shifts... but tune the car for ZERO detonation.

 

[scarface]

Is there any thing that has to be done to make fitt or drops right in insted of the turbo crank and can u use turbo rods with n/a crank

 

[vicious6]

Direct replacement. Everything should bolt right up.

 

[cool 84]

Rods are the same.

 

[J Banning]

Originally posted by vicious6
Direct replacement. Everything should bolt right up.

Yep.

 

[Ormand]

The rolled fillets on the turbo crank, and the 4.1 crank, are there to cut down on fatigue failures. The N/A crank will withstand just as much power, only for less time. How much less? It would be a pure guess, but could be a lot less. As seen above, the N/A crank will last for a while, making good power, so it's just a matter of how lucky you feel.

 

[J Banning]

UPDATE: 10.62 @ 125.45mph w/1.47 60'

That's shifting the 1/2 & 2/3 at about 5,900rpm & NO DETONATION.

 

[PEACHS]

I am beginning to think that the NA crank is way under rated. You hear of more turbo crank failure then the na cranks. I wonder if a heat or cryogenically treated crank would make them stronger then the rolled fillet crank.

 

[John Larkin]

The lack of N/A cranks in use distorts a true comparison. Unless Banning wants to endorse them, the build & tune is going to determine how they live case by case.

 

[Turbo-Archie]

Originally posted by vicious6
Direct replacement. Everything should bolt right up.

But wouldn't the N/A crank need to be ballanced with the new piston/rod weight?

 

[Ormand]

But wouldn't the N/A crank need to be ballanced with the new piston/rod weight?

That's a good question. It seems like Buick managed to get the rods/pistons for the 3.8 and the 4.1 to weigh close to the same, and maybe did the final balance with the flex plate and/or the balance hub on the front of the crank. May be true of N/A and the turbo, too, but I sure don't know.
The cryo treatment sounds like a good idea, but don't know about the cost As mentioned above, the rolled fillets are a fatigue fighter, to extend crank life cycles, not power capacity. Buick was covering themselves for warranty, who knows how long the lifetime might be? There are turbo engines with well over 100,000 miles (mine, for instance) and still going. If you were going to build a road race engine, to run for hours at high rpm, and high power, then fatigue would be a concern. But if you were doing that, why wouldn't you run an Eagle, or a Scat forged crank? As the turbo cranks get used up, I guess we will all learn more about the other cranks, and some will learn the hard way, unfortunately. But how else to learn?

 

[Turbo-Archie]

Originally posted by Ormand
That's a good question. It seems like Buick managed to get the rods/pistons for the 3.8 and the 4.1 to weigh close to the same, and maybe did the final balance with the flex plate and/or the balance hub on the front of the crank. May be true of N/A and the turbo, too, but I sure don't know.

Thats true but useing the same crank and making up the dif in the hub. Mixing an N/A crank with turbo pistons/rods and turbo hub should make it off ballanced.

I allways wondered that with the motor I ran. It didn't vibrate too bad and never fell apart.