Performance Cam

[chevyinlinesix]

Short and sweet;
I stated exactly why the stock camshaft works so well with everything else being 100% stock.
I also stated what makes the stock camshaft so bad once you start changing anything.
What is needed cannot be gotten with a re-ground military camshaft.

 

[buddy]

Nice theory. They MAY produce these big gains... I fully understand the theory behind changing cam dynamics, and what you indicate as fact ("they will make") applies fairly well to naturally-aspirated gassers.

wow did you just call me out that I was stating my theoretical opinion, how novell?

 

[JiFaire]

Sigh. No.

What I did was subtly (or perhaps not so subtly) echo your earlier post to TD...

You dont understand, the problem TD is with you emphatically posting your opinion as fact. Please preface it with IMO, IMHO, or the word might, may, some kind of qualifier.

Stand by your opinion all you want, but make sure others know its just that, an opinion.

Why did I do that? Because you followed up my (I thought) reasonable attempt to get the discussion back on the topic or Cams by making a post that ignored your own request to TD...

Stating that

Modded Camshafts and valve control will make a big gain in efficiency...

(emphasis added) seems to indicate that your opinions do not need to be prefaced with IMHO, but others' opinions do. I do indeed find an issue there...

That's all. As I indicated, the theory behind this is sound; what is not yet known is how well that theory applies to a 6.5 diesel engine. I'm actually quite interested in somebody trying this out and showing me that it does or does not work, and then creating more theoretical basis for WHY that happens.

If you wish to interpret this as "calling you out", fine. It's not my style, but I'm not too worried about it, either. I've been wrong before, and I'll be happy to be proven wrong on this topic, too. But stating things as a definitive and proving them are two different things.

Again... Can we please move the discussion back to the topic? Having to revisit ego-space every few posts is really counter-productive.

 

[JiFaire]

Short and sweet;
I stated exactly why the stock camshaft works so well with everything else being 100% stock.
I also stated what makes the stock camshaft so bad once you start changing anything.
What is needed cannot be gotten with a re-ground military camshaft.

Yep... makes sense to me, too. I really am looking forward to seeing some R&D on this.

 

[buddy]

Arguing those opinions or sparring about the semantics of the statements (does it really matter if the statement is prefaced with IMHO or if the paragraph is finished with "this is what I think at this time"?) <insert emphatic "no, of course not" here>

Applying double standards now, exactly my point. You make it a point to say my post is theoretical but when I try to make it a point that a mods post is only their opinion I get different response.

No need to respond....everyone gets it.

 

[randomid25]

Dude. Chill out. Seems to me that you are getting all bent out of shape because the majority of the people chiming in don't agree with you. If you believe there are big gains to be made with a cam change, do some testing and post up your findings. I too am curious about this subject and would like to see what gains could be had.
The mods are trying to keep the subject on topic while keeping the tone of the conversation civil without any disrespect to you. Seems to me that they are doing a great job.

 

[buddy]

randomid I could care less if people agree with me, including you, they can post their opinions like everyone else. You dont know me, so dont comment about me. Im simply pointing out some forum decorum that everyone else follows could have been used.

I had a simple request not to make definitive statements about who could benefit from the development and the next post was this...

Okay I'll type slow evidently the message isn't making the trip, For ......Most .....Of .....The ...... 6.5 .......Crowd......Aftermarket Cams........In......Their.....Truck.....Over.....&.......Above......What.......GM......Provided...Will.....Be.....Pretty.....Much.......Useless........Is......All......I .....Am......Saying,

I don't know how else to say it, and it isn't pidgeon holing we had been asked in the past to provide a performance area, just not enough discussions at the time to warrant it's own area.

By pigeon holing I was talking about limiting the applicability to racers, not about putting the thread in the performance section. It was a simple request to qualify the statements as opinions.

 

[Turbine Doc]

Is the .65 a "deadhead" system or dos it have a return line? And what are the big fuel issues w/ it?

6.5 has a return circuit, limitations on fuel are physical limits of the IP ability to move fuel beyond 92^3mm/1000 plunger output. Several folks making attempts to improve that.

 

[Diesel Warrior]

You dont understand, the problem TD is with you emphatically posting your opinion as fact. Please preface it with IMO, IMHO, or the word might, may, some kind of qualifier.

Stand by your opinion all you want, but make sure others know its just that, an opinion.

Lighten up Francis.

 

[Slim Shady]

Is there a good thread about camshafts? Any gains to be had? I had read the one from SSD provided some low end bump in performance.

With stock valves and springs would it matter?

Could it help off the line, or with slight turbo lag on ATT? Maybe get rid of that puff of black smoke that I didnt have with the GM4?

Thanks, Tom

We are working on a cure for the slight black smoke that you get. I don't think this is a problem with the turbo as much as it has to do with the fuel table curve. Kojo has a nice set up that I think will take care of most of the black smoke issue. I really don't notice any lag with my setup, how noticeable is your lag off the line.

The fuel curve for the gm series turbos is fat in the bottom end because it was developed for a turbo that is quite a bit smaller than the ATT.

My personal opinion is that boost below 1500 rpm contributes to lower end failure because of the harmonics and loading at low rpm, LUGGING a engine that is designed for higher rpm (V8) engines particularly: is not a good thing. Square engines ( bore and stroke the same or very close) are not LUGGING engines. NOW a six or 4 cylinder in line with a long stroke is truly a motor made to lugg, low rpm torque and horse power curve.

Hence the gm 6.5 makes torque peaks at 2100 rpm, where as the Cummings makes peak torque at around 1700 rpm, big difference hence the difference in the Holset turbo and the ATT design.

This is just my observation, and thoughts.

 

[buddy]

Yeah, I was looking to modify the fuel table, working on that too.

I have been thinking about the cam since that ATT discusion began, taking advantage of the backpressure drop. back when most insisted there is overlap of the valves, and I thought that would be terrible.

 

[Slim Shady]

Yeah, I was looking to modify the fuel table, working on that too.

I have been thinking about the cam since that ATT discusion began, taking advantage of the backpressure drop. back when most insisted there is overlap of the valves, and I thought that would be terrible.

If you are inclined, do the cam: if I had listened I would have never put the turbo on my truck. All you have to lose, is a little time and money. Curiosity killed the cat, satisfaction brought him back to life.

Just do it and find out, hell be stubborn headed like me, DO IT. ):h

 

[buddy]

Stubborn to get beyond those with the opinion that a bigger turbo would be useless for most 6.5ers, becauase the 6.5 aint for racing.

Lucky for me, and everyone else, Will is well on his way already, and I wasnt planning on getting into it until next summer. I will be eagerly following his progress. And what I had in mind is not as much as Will, more like what anyone rebuilding might do, hopefully not more than $1000 total, and thats not accounting for some parts that you might need to buy new OEM anyway.

For certain the cam at SSD is not what I would consider, just wondering if anyone had used it. The specs on it are not what I had in mind for increasing efficiency and power.

 

[buddy]

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.

CIL6, does that mean at lower compression ratio the valve drop will be greater? I was thinking of using a thicker head gasket to decrease compression ratio just a little. I believe those gaskets are available.

Obviously at TDC I want the valve closed, but if you have the 10 and 15 degree valve drop values I would very much appreciate that, so I could know how fast the cam has to get the valve down as close to TDC as possible.

Thanks

 

[SmithvilleD]

I agree with your thoughts on lugging the 6.5 is a bad thing for the bottom end. (At least on the positive side, we don't see the 5th gear issues in our NV4500's as often as the 5.9 Cummins guys:smile5

Also agree on the concept of bore/stroke ratio & how that impacts the rpm range an engine works well in.

However wouldn't you agree the fueling curve/mass airflow is still gonna be the overriding factor setting the torque curve in most 6.5T examples? The stock setup's peak torque is around 1750 - 1850 rpm. Would expect the ATT to move that somewhat higher as larger turbo's tend to do.

The torque peak of the Pennisular marine 6.5's are higher in the rpm range w/ the same bore/stroke. With bigger turbine & compressor section turbo's & a unique fueling curve well matched to one another & their intended use.

Has anyone actually spoken with Matt, or anybody else at Penisular to see if they've done any experimentation with different cam profiles?

It occurs to me they saw enough merit in improving 6.5 cylinder head flow via porting, that they now offer such a product. It would surprise me if they hadn't looked at cam profile also. Not that their 6.5 knowledge has to be the final word on 6.5 performance; but if you're gonna put the effort into creating a custom grind cam, it couldn't hurt to call them & possibly compare notes.

 

[Goldsburg]

I have done the cam analysis on the 6.5TD. Any changes to the cam (without modifications to anything else) will result in significant loss of bottom end power to realize only minimal gains in the mid-range and upper end. Changes to heads, turbos, etc, may minimize the low-end loss, but there will still be a loss. The GM engineers did their homework for making a "towing" cam.

So if you want to tow and use the truck as a daily driver, keep the stock cam. If you want to mod a 6.5 for racing or (for heaven sakes) truck pulling then their is definitely power to be gained with a cam change.

If someone wants to experiment with the commercially available "performance grind", then by all means go directly to Delta Cam to get the regrind and cut out the middle man. Talk to Scott about the 6.5 regrind that they make.

Regards,

 

[dragogt]

Has anybody put the numbers in a desktop dyno yet? Just curious what that would look like. Or is not applicable for diesels?

 

[buddy]

The thing is, everyone is right its not just a cam change. New rocker assemblies for higher lift, and I'm hoping honing comes down in price in the next 6 months for the exhaust manifolds. Things that wouldnt be out of the question during any engine rebuild if its under $1000 for the project. Although right now honing is expensive there needs to be some competition in that business.

since the fuel is squirted in based on a computer program with no regard for air, I shouldnt lose any amount of power from combustion that is currently there at the low end. I would think it would extend the torque curve not shift it. Because there is no lean condition.

Although if it does that, then maybe cruising at 75MPH will be more efficient and I'd still be happy enough. The use of the ATT will also change all the analysis done in the past.

 

[chevyinlinesix]

Has anybody put the numbers in a desktop dyno yet? Just curious what that would look like. Or is not applicable for diesels?

I am going to try that right now, numbers won't be accurate I don't think, but it should show a shift in power band.

buddy, yes lower compression by getting thicker headgaskets (or fly-cutting the piston) would increase the valve drop.

.056" intake valve drop, with .020" thicker head gaskets would net you .076"

I'll PM you the other camshaft info tomorrow :thumbsup:

 

[Matt Bachand]

We are working on a cure for the slight black smoke that you get. I don't think this is a problem with the turbo as much as it has to do with the fuel table curve. Kojo has a nice set up that I think will take care of most of the black smoke issue. I really don't notice any lag with my setup, how noticeable is your lag off the line.

The fuel curve for the gm series turbos is fat in the bottom end because it was developed for a turbo that is quite a bit smaller than the ATT.

My personal opinion is that boost below 1500 rpm contributes to lower end failure because of the harmonics and loading at low rpm, LUGGING a engine that is designed for higher rpm (V8) engines particularly: is not a good thing. Square engines ( bore and stroke the same or very close) are not LUGGING engines. NOW a six or 4 cylinder in line with a long stroke is truly a motor made to lugg, low rpm torque and horse power curve.

Hence the gm 6.5 makes torque peaks at 2100 rpm, where as the Cummings makes peak torque at around 1700 rpm, big difference hence the difference in the Holset turbo and the ATT design.

This is just my observation, and thoughts.

I thought 6.5 made max torque at 1750rpm, thought from seeing old dyno charts. Do you have a chart showing 2100? Although, 2100 is EXACTLY where I sweetspot my RPM's for driving, I even changed tire-size to accomodate road speeds and 2100 rpm. So I agree, just would like to see it on a dyno as I was under the impression itw as 1750. IN MY OPINION lol