Power drain from Timing Chain / Valuable Build Tips herein...

[galderdi]

Sorry if this is a repeat. I did search with no hits but maybe the key words are different.

 

I am considering the Kameari Twin idler chain tensioner in my L28 build. I am just wondering if anyone has any idea of how much power drain is involved with the standard tensioner? In other words how much power am I likely to gain by swapping to the Kameari setup?

 

I know there are other advantages but I am trying to justify the cost.

[randy 77zt]

I think the idea is about more accurate cam timing + possably less friction from losing the timing chain tesioner block.If you had a cylinder head that was milled alot and had an adjustable top timing chain sprocket you could easily adjust for your combination of parts.

[Tony D]

Randy has it: it's for the loss of cam timing and maladies related to that not friction reduction.

Lacking your engine specs/intended use and your statement of "justification of costs " likelihood is high your engine will not be in sufficient tune where it will require the device, unless as Ranfy stated...you milled a mile off the head.

[Tony D]

You want "power drain" reduction in that subsystem...

Look to sliding friction of cam live on rocker and valve spring weights.

 

Roller Rockers free 20+ HP but is hard to quantify empirically due to using different cam profiles.

[johnc]

Well... my Sunbelt built 325hp L6 could almost be turned over by hand using the balancer (with the plugs out) so my guess is the power drain in negligible in a properly assembled engine.

[rsicard]

John:

 

Explain how there can be SO LITTLE friction in a L6 engine that it could almost be turned over by HAND! That one is a BIT HARD TO SWALLOW. What is meant by a properly assembled engine? Please go into detail how friction was reduced to that level. Six Ring Packs, Crank Bearings, Cam Bearings, Oil Pump all contribute to friction. Also with a finished engine, upper end cylinder head valve springs, rocker arms, etc. also promote resistance to turning over. What was the measured value of friction by Sunbelt, of the short and long L6 engine? Would be nice to hear the reality of the engine build.

[johnc]

The biggest friction generator, IMHO, is valve spring seat pressure. The cam design and valve spring package Sunbelt designed for my engine (and as a package for other L6 engines) has 25% less closed seat pressure then stock yet was good for 8,000 rpm. That and perfectly round cylinder bores, loose forged pistons, a crank that weighed 35 lbs, and lots of detailed work to reduce internal friction.

[rsicard]

JohnC:

 

With all due respect to your skills, Valve spring seat pressure should be a fraction of the total Piston Ring, Crankshaft Bearing, Camshaft Bearing and Oil Pump Friction. Assuming VERY round cylinder bores, loose forged pistons, less the rings, should have very little friction in a vertical bore engine. The Rings have the largest amount of friction in the engine even though they may be only two per cylinder and VERY thin. That would necessitate the use a a vacuum pump to evacuate the crankcase pressure. Without the metrics of actual measured friction in the short and long block assemblies, it is hard to determine actual friction levels. Crankshaft bearing clearances, not weight, have to do with overall engine friction. Same is true with the camshaft.

[johnc]

I don't profess to have engine skills. I was just repeating what Jim at Sunbelt told me when I asked why the engine was so easy to turn over. When I posted IMHO, I should have post WJTM (What Jim Told Me).

[roger280zx]

It is well known that the L6 is especially sensative to exessive valve spring pressure. Most cams sold for these engines have imprpper lobe profiles, and Jon's engine proves that when as much attention is paid to things like ring packs and bearing clearances, as is paid to lobe profiles and adequate spring pressure... amazing things happen at the dyno, then at the track.

[Tony D]

I believe someone else spoke of valve spring pressure...

 

riscard assuming far too much. Bearing drag in a properly (there we go again) engine --- for instance the crankshaft --- it will freewheel spin given a stout turn on the drive flange if you have a strong enough grip. SUUUURE you can assemble an engine tight as a frogs arse, you aren't going to make power either. That engine is wasting power to overcome friction. Hence the qualifier "properly assembled"...

 

I have had engines that turn over by hand---does John mean fingertips on the crank pulley or a thumb and forefinger on the ring gear? Or a single finger across the ring gear? Rotational friction is a matter of proper assembly lube, proper clearances, and proper insertion of the ring and piston pack.

 

But to say the tension of the rings in ANY way comes close to the forces present by the valve springs pushing up against the cam is ludicrous-especially with low-tension racing rings. The friction of the valvetrain is considerable, to turn the cam in a spring dyno generally requires at least a 5HP, if not 20HP electric drive motor!

 

The difference between a short block and a block with the valve train being actuated is significant and easily quantified. Put your torque arm on the crankshaft nut, and turn it over on a short block using a digital hanging scale...you can calculate ft-lbs if you measure correctly. Then put the top end on and try it again. Interpolation from that point is easy.

 

You are going to be surprised at the result. Most properly assembled bottom ends will, if given a stout turn continue spinning for a short bit. Put that valve train on there, and not only does turning torque go up considerably you don't have that 'freewheel' for 8-10mm up bore like you did previously.

 

The last bastion of frictional reduction in the L-Engine is the valve train. Not many have gone after that parasite. Malvern tried with good results but died before mass production became a reality. All the rest is simply assembly tolerances and lubricant.

[rsicard]

Tony D:

 

How many engines, which have been aftermarket machined, have you assembled to specifications and found "will freewheel spin given a stout turn on the drive flange if you have a strong enough grip"? Just forget about an assembled LONG BLOCK. Just working with the short block wherein the only friction is the Crank Bearings and piston rings.

 

What are the typical clearances for Crankshaft Main and Rod Bearings?

[roger280zx]

You gotta have that Kung Fu grip! Haha

 

Getting back on topic, can anyone speak to their experience of valve train stability provided by the tensioner. It seems to me that most chain slack due to extensive decking can be addressed with the available short valves and tower shims. Given those options it would be quite a stretch for me to make the substantial investment in this system unless there is some other particular gain. I can see that saving your race head, already filled with hours of porting and nice valves, by decking and removing the slack with the Kameari idlers. But to get back to the o.p. what is the benefit (if any) to include the twin idlers in your clean slate build?

[ctc]

My understand from discussion on this site and others is that the Kameari set up adds timing chain stability at RPM's that a normal street engine would not see. I remember seeing a video of a Kameari test, where they made a plexiglass front cover and videoed the timing chain slappping against the guide. They then installed their tensioner and chain slap was reduced to near zero with RPM's in excess of 10K. Again, from memory, a stock chain guide's life can be measured in minutes at RPM's greater than 10K. If the chain is hitting the guide it is causing friction and taking horsepower. On a maximum effort race engine that see RPM's above 9K regularly, stock parts will not cut it.

[ctc]

And not to end this discussion, but searching would have dug up this gem from the past......

 

Kameari idler discussion

 

Again, one should always look at their engine as a combination of parts to achieve a goal.

Edited April 6, 2012 by ctc

[randy 77zt]

johnc's engine is probably built for a certain scca class .When the rules limit what you can do you have to find all of the horsepower you can get.Very carefull assembly(not like me-I run junkyard parts) can get some extra hp but you pay the $ for the talent..My opinion is the biggest horsepower loss is the power it takes to open the valve springs.Engine builders like Sunbelt or Rebello have built enough engines to know if a valve spring with lower tension( and less hp loss) will work for a certain customers intended use.

[Tony D]

Tony D:

 

How many engines, which have been aftermarket machined, have you assembled to specifications and found "will freewheel spin given a stout turn on the drive flange if you have a strong enough grip"? Just forget about an assembled LONG BLOCK. Just working with the short block wherein the only friction is the Crank Bearings and piston rings.

 

What are the typical clearances for Crankshaft Main and Rod Bearings?

 

I personally have done half a dozen L6's and the L4's are a given.

 

SBC Chevy? I've not done one to this level, I don't know. Infinity IRL 3500 V8? Didn't think to try... VW Type 1? Without pushrods, yes as well.

 

The question remains as to "what clearances" and what definition you give to "aftermarket machined"?

 

How many people here know how to check for a bent crank?

 

Bearing clearance concentricity check ASSEMBLED bore-to-bore?

 

People "Assemble" things all the time and they "Work Fine" as always this goes back to a definition of "Works"!

 

Some people are more meticulous than others. If your crank doesn't freewheel several revolutions in the mains once assembled before putting rods on---you need to go back and check more closely! Something isn't right.

 

Will it "Work"? Sure. Is it right? Depends on your preparation standards.

 

FYI: The OSG TC24B-1Z on display at Nostalgia 2-Days recently was EASILY turned by a damper placed on the crank snout till compression built up. Even I was surprised, they claim 400+ out of that engine and it uses timing GEARS... so maybe it's in preparation standards that people are comfortable or accustomed to that is the root of this tangential discussion.

[rsicard]

Tony D:

 

Now my curiosity is peaked. Please expand on:

 

"Some people are more meticulous than others. If your crank doesn't freewheel several revolutions in the mains once assembled before putting rods on---you need to go back and check more closely! Something isn't right.'

 

 

 

Is this level of quality attainable? How many aftermarket engine machine shops achieve this level of quality? What kind of equipment and techniques does it take to achieve this result? I would like to achieve this level of quality in V8 engine rebuilds. Please advise. Thanks.

[PMC raceengines]

Well i spend some times, hours to make my race cranks spin , working in 10ths to get where im happy

lapping thrust berings and swoping berings is normal , as its so hard to get a crank thats right after its been played with by so called pros that have crap standards . BUT when its right the crank spins free with a finger , then move on to the next part , rings must have the same tension and gap , bores must be strate and round ,it all adds up . A short motor will tern by hand ,, 14,lbs

of force is nice . i have tested the twin idler and normal guide back to back , to 8000rpm on a super flow engine dyno , there was a hp gain at 6500 4hp to be exact and 7500 was 6hp up and 8000rpm was up 7.5 hp ,,, but as a street engine that rpms to 5000 dont bother.

[rsicard]

PMC raceengines:

 

Good to hear you chime in. The statement "A short motor will tern by hand,, 14,lbs" does this mean 14 foot/pounds torque applied to turn the short block assembly over? Please reply. Thanks.