Quick main question..

[Turbo6Smackdown]

Look at the main caps on these blocks here. http://www.turbobuick.com/forums/parts-sale/296820-new-v6-turbo-blocks-sale.html

Are those factory stock? If those are plain old production caps, what do people need billet mains for? Are those not cocky enough? They look freakin strong to me!

 

[DailyDrifter]

Look at the main caps on these blocks here. http://www.turbobuick.com/forums/parts-sale/296820-new-v6-turbo-blocks-sale.html

Are those factory stock? If those are plain old production caps, what do people need billet mains for? Are those not cocky enough? They look freakin strong to me!

They look stock, Billet caps are alot stronger. I think some people have broken caps, or they flex under high load (correct me if im wrong)

 

[dr_frankenstein]

yea those are stock mains.

not strong enough?

If you could slow down a turbo engine enough to see with the eye at full boost churning 6000 rpms the insides move and flex around like gum.

the billets are harder and more rigid, helping to avoid the excessive walk and "gum" action at full boost / 6000rpm.

A.j.

 

[Turbo6Smackdown]

Holy ****. These engines are bad as hell, if they can produce the hp/tq necessary to break those caps.... I guess it's good that I'm going billet mains all the way down.

 

[bison]

Holy ****. These engines are bad as hell, if they can produce the hp/tq necessary to break those caps.... I guess it's good that I'm going billet mains all the way down.

Most break caps because of detonation not because of power. I had over 10 minutes of wide open throttle at 600+hp on one and the caps held up and still looked really good on the mating surfaces. At one point before it cracked the piston it was over 700hp/tq

 

[Turbo6Smackdown]

I see. I know this is an odd question, and hard to answer but.. with bad detonation, am I assuming correctly, that it doesn't matter how low your hp is? If you have bone stock hp levels, will bad detonation still bust one?

 

[joe_schindler]

Most break caps because of detonation not because of power. I had over 10 minutes of wide open throttle at 600+hp on one and the caps held up and still looked really good on the mating surfaces. At one point before it cracked the piston it was over 700hp/tq

I hope you had good ear muffs. How much fuel did you use in 10 minutes?

 

[joe_schindler]

I see. I know this is an odd question, and hard to answer but.. with bad detonation, am I assuming correctly, that it doesn't matter how low your hp is? If you have bone stock hp levels, will bad detonation still bust one?

I probably won’t explain this completely correctly but; no.

You can have detonation at extremely low HP levels. You see it all the time in traffic jams. That type of detonation is more likely to crack a piston skirt or hammer on the bearings than knock out a main cap.

At higher HP; detonation simply adds more load to the already loaded crank, mains, and block. At some point; the weakest link will let go.

 

[Turbo6Smackdown]

thanks. sort of confirmed what I had been thinking.

 

[Mike Licht]

I believe more people break caps to due to the stock crank flexing/twisting. that is why the bearings come out worn so bad on one side in motors that have been run hard. Just my thoughts.
Mike

 

[Turbo6Smackdown]

If that's the case, would just a forged crank help? Would billet mains be needed on a forged unit?

 

[joe_schindler]

Imagine a speghetti crankshaft spinning in a Play-Doh block.

Now imagine a forged steel crank spinning in a Play-Doh block.

 

[bison]

I hope you had good ear muffs. How much fuel did you use in 10 minutes?

Ear muffs?You can figure it out. Its a rough estimate of accumulated time. BSFC is about .63lb/hr per hp. At about 650hp average

 

[bison]

I believe more people break caps to due to the stock crank flexing/twisting. that is why the bearings come out worn so bad on one side in motors that have been run hard. Just my thoughts.
Mike

I agree. The center mains in my high mile high hp engine showed lots of wear on the center bearings but almost zero metal transfer between the cap and block.

 

[Turbo6Smackdown]

Imagine a speghetti crankshaft spinning in a Play-Doh block.

Now imagine a forged steel crank spinning in a Play-Doh block.

So will a forged crank with billet mains all the way down not be any stronger?

 

[joe_schindler]

If that's the case, would just a forged crank help? Would billet mains be needed on a forged unit?

Imagine a speghetti crankshaft spinning in a Play-Doh block.

Now imagine a forged steel crank spinning in a Play-Doh block.

So will a forged crank with billet mains all the way down not be any stronger?

A forged crank with billet mains would be stronger than the stock setup (spaghetti crank and Play-Doh block).

Upgrading only the crank doesn’t buy you much; because the block will still flex.

Billet caps will add some level of strength; I don’t have a measure for that.

A stud girdle is probably a more economical and probably stronger alternative to the billet main caps. I don’t know that billet caps and a girdle are better.

There is no bulletproof combination. At some point; something will let go.

 

[Turbo6Smackdown]

girldles are cheaper? I thought they were more expensive. What about the maching to do one. Isn't that more expensive?

 

[Mike Licht]

For me the best setup is a Steel crank and some billet caps (front 3, rear almost never has a problem) Girdle on a 9 second or faster motor.
Mike

 

[Turbo6Smackdown]

I see. You don't think a block stiffened with a girdle, will last any longer than a billet capped block? 10 seconds and faster don't produce that much torque ya think?

 

[Mike Licht]

Well I put almost 200 10.70-10.50 passes on a junkyard shortblock with the origianal bearings and rings in it. (no caps or girdle) It then went in another car and was driven for about 4 years without problems, secret? no knock, car would have gone 10.20 with an agressive tune up. When we finally took it apart the bearing were wore very bad on one side and looked fine on the other. (crank twist) Bob had a 4.1 stage 1 with a steel crank that he drove very hard at the track a few times and lots of street miles, 2 broken main caps in the end and the bearings were not too bad but lots of cap movement and metal transfer. Dave Bamford had many 9 second passes on a 109 block with steel crank and billet mains, no girdle, this one had an argressive tune with no block or main problems until the block finally failed in the low 9 second area. This makes it hard to anser your question unless I know more about the car and set up, there is no "general" answer. In my experience the caps are my first choice over a girdle. And yes I have seen stock caps break with a girdle installed, it does hold them together however.
Mike