double roller plus tensioner plus bad luck

[Steve Wood]

ow......

[Pyro6]

That yours??

[Steve Wood]

nope..I don't use a tensioner...gu y sent the pic to me asking about using a tensioner on a roller chain a second time-this one made 3000 miles before it broke, got caught in the crank gear, broke the chain and destroyed the cover and front of the pan

[Pyro6]

Thought so, had to ask.

[Forzfed]

What a mess!  Glad I'm not using a tensioner.

[Scoobum]

Stock junk works just fine for me.

[Steve Wood]

he has a roller cam

[Scoobum]

Like I said...my stock junk works just fine.

[Steve Wood]

Be that as it may, there is a benefit to using a larger cam when employing a large turbo.  And, it seems that a roller cam produces better longevity when going to that larger cam.

[Charlief1]

That's a TA timing cover I believe. I believe you can use a tensioner, but not the stock one. It's a hard rubber so it would get chewed up easily. Now if you went with one for a later 3800 it's got a very hard plastic block so it wouldn't be subject to the same issues.

[Scoobum]

Be that as it may, there is a benefit to using a larger cam when employing a large turbo.  And, it seems that a roller cam produces better longevity when going to that larger cam.

Longevity...ye s. Be that as it may...there's two S2 cars in the Toronto Area and a twin turbo SBC Regal with roller cams running 11's. Maybe they should try flat tappet?

[earlbrown]

That looks like a hi-vo chain, that's smooth on the outside, which is OK to use with a tentioner.

 Blow up the pic and look at some of the link pins. It looks like it might have been a chain failure that resulted in the carnage, not a tentioner problem that started it.

[Steve Wood]

Don't know, guy had three thousand miles on the engine, tensioner came apart, got caught between the chain and the crank gear and locked up breaking the chain and wrapping a section around the gear ending up in the damage to the cover and pan you see.

If the tensioner is not made to be used specifically with a roller chain so that it meshes correctly, I am not doing it...I don't care if it is hard rubber, or jello, I am not trying it

[Steve Wood]

Be that as it may, there is a benefit to using a larger cam when employing a large turbo.  And, it seems that a roller cam produces better longevity when going to that larger cam.

Longevity...ye s. Be that as it may...there's two S2 cars in the Toronto Area and a twin turbo SBC Regal with roller cams running 11's. Maybe they should try flat tappet?

I don't know anything about the cars so I have no idea why they don't run better but I know there are lots of possibilities that don't necessarily have anything to do with whether the cam is a roller or a flat tappet

My statement was that a roller cam made it easier to use the potential of a large turbo.  Given that a turbo is simply an air pump, if one puts a large turbo on a car that has poor volumetric efficiency such that the output of the turbo cannot be consumed, then the car is not going to perform to its potential--assuming the engine builder had a reason for selecting that turbo...now, we know assumption is dangerous and perhaps the Toronto engine builders were dealing with too much assumption and not enough understanding.

In a 231 " Buick, a major bottleneck is the cam profile when trying to use a big turbo.  A bigger cam that will turn more rpm will allow the turbo to make more use of its capacity because all formulas for VE depend greatly upon total rpm used.  Given that we normally don't like to turn a stock block to 7000 rpm, a roller cam allows us to use a lobe that provides more area "under the curve" and start increasing efficiency of the process at a lower rpm.  It will also allow us to spin it up to around 6000 rpm which, in my opinion only, is about the point where stock junk starts edging upon the total junk point.  So we get better efficiency at a lower rpm and carry it forward to a point about a thousand rpm higher than so called stock junk.

If we use a flat tappet cam, we don't gain as much under the curve and we have to use quite a bit of spring pressure to keep the lifter planted which might be okay on some cars; but given the poor lifter location on some of the lobes of our engines, we shorten the life of the lifter and cam-hence my longevity comment.  And, of course, we are still rpm limited on a stock block.

It's all about the synergy of the parts in the combination if one wants to give the tuner the best chance of squeezing out the potential hp.

[motorhead]

Well, now ain't that some shit?

For our LS1 build I am employing an "LS2" chain damper to prevent potential chain wrap.  This damper sits inside the chain/gear assembly in the void between the gears - single row timing chain with a .600"+ lift cam and 400lb/in dual springs.

Tell me again why we saddle ourselves with these dinosaur engines for reasons other than nostalgia?