Performance Cam

[chevyCowboy]

thanks for clearing that up iv searched and never really found any thing

 

[dragogt]

Dragogt

The precup (located in the head) is the actual combustion chamber.
The injector, glow plug are in this little chamber and this is where it all begins.

As the piston approaches TDC the air in the cylinder is forced into the precup through the little slot that connects to the cylinder.

The angle of the slot in the precup starts the air swirling around inside the cup and then the fuel is injected and combustion begins.

The hot gases build pressure and then exit the pecup into the cylinder.
The little indents in the top of the piston direct the outfloe from the precup into two swirling masses of burning fuel and this causes more mising with available oxygen in the cylinder.

Here is a pix of SOME of the different cups used.

The concept of the precup is to provide a cozy little place for combustion to start and to help the mixing of air and fuel.

The Precup design has been around for a long time. Caterpiller used the precup in diesels back into the late 30's and continued its use way up and even into the 70's

Emmision regs and advancements in design eventually forced the precup design out.
Engines like the Cummins 5.9 have the combustion chamber in the piston top.

The precup has many advantages but also is a slightly dirtier engine (emissions)

The precups in the 6.2/6.5 morphed a lot over the years of production.

The early 6.2's had a very tiny port in them and as time went by the port changed sizes and shapes many times with various little marking being stamped into the cups to identify them.

The late 6.5 TD cups have a diamond stamp on them.
These had the largest size port ever used in a prduction 6.5

As a rule of thumb the smaller ports give higher velocity and better fuel economy than the large ports.

Early 6.2's in K Blazers could be counted on if driven right to deliver 24 MPG Highway with ease.

This was due to in part to the precup design and the fuel delivery settings.

The J series 6.2's of the later 80's had a much larger port in the cup plus a higher fuel setting. They produced more power but at a reduction in MPG's

The 6.5 saw several incarnations of the precup. The N/A version had two common sized ports and the Turbo Charged models saw at least three changes. The most common being the Cups stamped with a "T" and also the one with the "Diamond"

The "T" Port was used in the 92-93 engines and the 94 and later usually had the diamond BUTTTTTTTTT there was always the odd duck.

Now then there is Military stuff, All bets are off here. These critters had a variety of stuff that in many cases was peculiar to the MIL stuff (Just like Injection pumps)

The precups can be swapped back and forth to get just what you want.
The only things is that all the cups have to be the same.

I have pulled engines down that have had two different sets of cups. (heads swapped)
This is a bad thing as it changes the running characteristics of each bank of cylinders.

I have even seen two or three deifferent cups in one head. OMG what were they thinking????????//

The biggy is to be sure the cups are matched (same markings) and they they sit flush to no more than about .003" above the head surface. (Never lower than the surface)

Some aftermarket cups will fit GM heads and some wont.

Some shops surface heads with the cups left in place. This is a bad plan. The cups should be machined afterwards to fit correctly. (Takes a special jig)

The aftermarket heads I have seen come with the precups pressed in and the heads ground afterwards to assure a good finish ?????????/

I have used Clearwater heads and they work fine. (these had the cups and heads finished at the same time)

I used the "T" cups in my DaHooooley build this summer.
Not because of anything special, but because I found them for a right price (free) and they were not cracked all the rat poop like my diamind cups were.

The ports get very hot and they will crack at the mouth. The cracks will propagate outward and if they get over 3/16" long the cup is junk.
If the crack crosses the fire ring on the gasket it will eventually cause the gasket to fail.

Hope this is useful

MGW

Ah ok tks, So basically they work the same as the IDI chamber on a 6.9/ 7.3..

Except that that they are interchangeable, is there any performance difference between them all things being equal?

 

[Woody35]

the diamond precups in turbo 6.5 f engines have the best performance

 

[Missy Good Wench]

Yes the diamond was and is the last incarnation.
Even the aftermarket stuff from Clearwater is marked with a Diamond. Now this said the aftermarket stuff is different. The factory cups are non magnetic and the aftermarkets will see a magnet stick them.
The port size seems to be the same though. The interior shape is also different on many of these cups too.

I used the "T" cups because I got a set FREE from a used set of heads.
The difference is very slight and will likely make zippo difference is power output


MGW

 

[Missy Good Wench]

There may have been some connections to emmission levels too.
I dont know this to be an absolute, but would suspect that there might be a connection to the precup designs and the emmision levels.

MGW

 

[chevyinlinesix]

Yes the diamond was and is the last incarnation.
Even the aftermarket stuff from Clearwater is marked with a Diamond. Now this said the aftermarket stuff is different. The factory cups are non magnetic and the aftermarkets will see a magnet stick them.
The port size seems to be the same though. The interior shape is also different on many of these cups too.

I used the "T" cups because I got a set FREE from a used set of heads.
The difference is very slight and will likely make zippo difference is power output


MGW

I think you got it backwards, the factory precups are non-magnetic (300 series stainless is the most likely alloy group)

The aftermarket precups are magnetic from what I have heard, and it sounds like they are a 400 series stainless (which generally has a higher chromium content among other things that make it magnetic)

After talking for a while on the phone with Clearwater Cylinder Head, I would never want to use their heads, or anything else on my engine.

 

[Missy Good Wench]

I think that is what I said, The stock stuff is NON Magnetic and the afternarket will stick to a magnet.

Its early, I know he he he

I have used heads from Clearwater and had great luck.
Ratman has a set on his truck, same feelings.

Their service was great and the price was even better.

What bothered you with these guys??? Curious I am.

One of the other folks that comes here works for a shop that services the little delivery chip trucks and they buy the clearwater heads many sets at a time and have had great service from them

???????????????????

MGW

 

[Brooklyn Tow]

I try to leave materials that are useful and helps others.

MGW

And it's apprieciated Sister.

 

[chevyinlinesix]

I think that is what I said, The stock stuff is NON Magnetic and the afternarket will stick to a magnet.

Its early, I know he he he

I have used heads from Clearwater and had great luck.
Ratman has a set on his truck, same feelings.

Their service was great and the price was even better.

What bothered you with these guys??? Curious I am.

One of the other folks that comes here works for a shop that services the little delivery chip trucks and they buy the clearwater heads many sets at a time and have had great service from them

???????????????????

MGW

I think you right, it must have been too early in the morning and I obviously read it wrong :mad2:

I was going to get my heads from them, but as I found out, their stuff is cast in China "with whatever metal we send over there" is what I was told. I like to know what grade the material is I use for everything, and also was hoping it was cast in either Canada or the USA.

 

[ak diesel driver]

there's someone one ebay selling blocks that are cast and machined in canada might check with them.

 

[buddy]

So it seems strange to me I havent heard much about the cams on these engines. Like it hasnt been well explored possibly due to preconceived notions about turbo diesels. I was hoping someone had actually tried a different grind and what it was and the effects. I'm interested in trying it, but need to find a donor camshaft I guess, because I think I read that you can get custom grinds for $150-200 on a core cam.

So since we got onto precups, which ones are used in L56 engines versus L65 engines.

 

[chevyinlinesix]

there's someone one ebay selling blocks that are cast and machined in canada might check with them.

Thanks aka diesel driver, I called them too, and sadly they receive them from Canada, but are cast in China. Places tend to give you the truth when you tell them how high profile of a build you are doing. That's when you find out what they are all about, is becoming a real eye-opening experience for me.

Your prices on custom re-grinds are accurate buddy. Call up Crane Cams, their prices may be lower now due to their recent re-structuring.

 

[mr_goodwrench_06]

Here's my take on some things...Doing work on the intake side of the engine will release more power than people tend to think. Boost pressure is a result of restriction to flow, right? Building boost costs power. I have seen turbocharged V8 gas engines loose boost psi and gain good amounts of power by porting/polishing matching etc. Less restriction to flow means the turbo has to build less pressure to achieve the same air flow. A turbo that doesn't work as hard doesn't rob as much power from the engine.

These engines have a lot of power that never surfaces because it costs alot of power to run them. The power is already there, we just don't see it! Freeing up this power allows more to get to the wheels without taxing the inner workings past the safety point.

I personally believe that a cam change, a turbo change, headers and some work on the heads could result in a bunch of power.

Just MHO

Bill

 

[mr_goodwrench_06]

Has anyone actually used a degree wheel on a stock cam? I'm just wondering how accurate the numbers being used are. Are the valve events quoted at a certain lift value? The exhaust valve needs to be absolutely closed BTDC and there can be absolutely NO overlap...We can work with pretty steep profiles though, I guess. Roller lifters allow for that.

Just wondering...

Bill

 

[Missy Good Wench]

I have degreed stocks cams. Not sure if the factory specs are taken from the .050" lift point or not.
Many cams are speced from 000" to make them look better.

Custom cams like crane, Isky etc are as far as I have seen "Right spot on what they print on the spec sheets"

I did get a crane "Blue Print" cam one time that had the key out of whack and I did not degree the thing (SBC) truck ran like crap and I had to redo the thing.

Degreed it out, found the issue and then yanked the cam and replaced it.
Easier to do it before buttoning the thing up though AAAAAAAAAARRRRRRRRRRRGGGGGGG

On the 6.2/6.5 the valve events that happen close to TDC such as exhaust closing, definately NEED to be shut before the piston reaches TDC.

With the very close VTPC any deviation from stock is going to cause a wreck.

IMHO
The cam profile on these engines is likely quite adequate for the amount of power that these engines can produce without going into self destruct mode.

A good power chip (electronic engines 94 and later) or a turned up DB2 (6.2 and early 6.5 ** 92-93) plus a really good exhaust of 4" diameter plus a turbo that can flow some serious air will take these little engines right up to and beyond any reasonable power levels,

Chasing any little last tid bits of performance is IMHO a waste of time here.

Now make no mistake, I love the 6.2/6.5 even with their faults.

Guess I am a sucker in love with the underdog.

These little engines were never designed to be a 400 HP moose motor.

They were concieved to deliver up to about 200 HP (flywheel) and produce some hefty torque numbers in the upper 300 to low 400 ftlb range.

The real point that made these engines so great was that a 7000# DaHoooley 3500 pickup can cruise at 60 MPH and under ideal donditions get near or slightly better than 20 MPG

The competition is not in this arena.

A well setup 6.5 can run with the big Dogs but its not gonna go head to head over the long haul with highly modified Cummins and or 7.3 strokes

A 6.5 with some work can run off from a 7.3 stroke that is in near stock trim.

I am always interested in cool stuff and Cams are definately cool stuff.

I really believe though that worrying about the cam profile in one of these engines is in effect, "Chasing the wind"

If someone is interested, try giving Peninsular diesel a call. These guys have been building 6.2/6.5 since the early days and they make some serious HP from their marine engines.

I would ask them if there is any tweeky or tricked out cam profiles for this application.
If these guys are not using anything other than stock cams, its a good bet that there is little to be gained in that area.

Peninsular builds a Marine 6.5 that will make a Metric Buttload of power and do so reliably. This tells me that if there is some tricks, they will know of them.

I have spoken to these folks a few times and they were great to talk to.
They are the source for the "Forged Cranks" for the 6.5

Just some thoughts

MGW

 

[buddy]

What do these values mean?
Intake valve drop @ TDC = .056"
Exhaust valve drop @ TDC = .057"

Is it that the valve are open somewhat at TDC but not fully? Like the open and close are complete open, but they are still both open at TDC?

Is there a reason the exhaust valve lift if shorter than the intake lift? I wonder if we could get 0.5" on both with stock valves and springs.

If someone has actually tried and failed then that would be one thing, but I have not heard of this, so the skyis the limit on power as far as I'm concerned. As long as temps are in check then the engine will take it. Is the 6.5 block weak compared to others that would cause it to break just because its pushing more torque, or is it unchecked temps that kill them?

Thanks

 

[chevyinlinesix]

mr goodwrench 06, I took got all my specs using a Comp Cams professional degree wheel kit. I took all my measurements at .050" off the seat, as this is the industry standard, and makes it easy to compare camshaft profiles to ones that are already produced. I checked everything over 7 times, took me a whole day.

Buddy, valve drop @ TDC is simply how far the specific valve is needs to open to contact the piston at TDC. For example, the intake valve can open .056" @ TDC, that is the point at which it contacts the piston. The reason the numbers are SLIGHTLY different between intake and exhaust is just because the valves seats are a bit differently recessed into the heads.

I also have measurements 10 degrees and 15 degrees before and after TDC for both the intake and exhaust valves, along with a slew of other measurements that I did not include. This is because those measurements are if you run very tight piston to valve clearances, and were necessary to order my set of custom billet pistons.

As for the springs, factory stuff breaks under factory specs. so the choice is yours. I'm not using any factory parts because the springs can't handle the high lift, RPM, and ultra fast valve opening rates.

The 6.5 block is weak in my opinion, but for yo with proper parts selection.

 

[chevyinlinesix]

Cams have been explored, been found to be low bang for buck if at all improvements, I spent some quality time at a dyno meet with Dennis Garmon http://www.garmonsdieselperformance.com/ one of *THE GUYS* in Diesel performance world I asked his opinion on it, he recommended that there are better ways of going for power, cams were not on his list of things he likes to do to a performance Diesels, that was March 2005, maybe he's changed thought on it, but I doubt it he was pretty convinced at the time it was more or less a waste of $$$

Turbine Doc, I mostly agree with your statement as it applies to stock manifolded engines. But, in an engine where other options of making power have already been exhausted, and someone is trying to get that little extra edge, there is room for improvement.

I wouldn't take anything from many "performance shops" too seriously, as they consider the 6.5 diesel a waste of money, you WILL get laughed at. So how can they justify all the time it takes to properly design a camshaft, if they are putting it in a crappy engine? Once a powerful 6.5 diesel is built, more people will realize the potential these engines have.

This is what I say to people who think a 6.5 diesel can't be powerful "It's just an engine"

Keep the questions coming buddy

 

[Matt Bachand]

Turbine Doc, I mostly agree with your statement as it applies to stock manifolded engines. But, in an engine where other options of making power have already been exhausted, and someone is trying to get that little extra edge, there is room for improvement.

I wouldn't take anything from many "performance shops" too seriously, as they consider the 6.5 diesel a waste of money, you WILL get laughed at. So how can they justify all the time it takes to properly design a camshaft, if they are putting it in a crappy engine? Once a powerful 6.5 diesel is built, more people will realize the potential these engines have.

This is what I say to people who think a 6.5 diesel can't be powerful "It's just an engine"

Keep the questions coming buddy

Lovin your enthusiasm and your threads bud. Keep the progress coming!

 

[Turbine Doc]

Turbine Doc, I mostly agree with your statement as it applies to stock manifolded engines. But, in an engine where other options of making power have already been exhausted, and someone is trying to get that little extra edge, there is room for improvement.

I wouldn't take anything from many "performance shops" too seriously, as they consider the 6.5 diesel a waste of money, you WILL get laughed at. So how can they justify all the time it takes to properly design a camshaft, if they are putting it in a crappy engine? Once a powerful 6.5 diesel is built, more people will realize the potential these engines have.

This is what I say to people who think a 6.5 diesel can't be powerful "It's just an engine"

Keep the questions coming buddy

This is the crux of my position/statement CIL6 my recommendations are targeted toward the average 6.5er not the performance guy with custom intake, fueling etc. SSD's "performance cam" sold to the average 6.5er does little except to lighten the wallet, as far as Dennis Garmon just being a speed shop guy, not hardly, he's probably one of the best in the Diesel drag circuits and otherwise heck of a nice guy to boot,

His recommendations or lack of it for cams as a performance improver for Diesels is based on work with his 500rwhp #2 only daily driver Dodge Cummins, the recommendation was there are better things worth doing than cams, you are custom with your intake & fueling so for you cam might be and option, for rest of the 6.5 crowd not going all out cam not best choice for things that work on the 6.5.

We now have a performance area it's going to be interesting to monitor your pushing the envelope there, wishing you success in this endeavor.