Colt Cam for BRM, another piece of the cam failure puzzle?

This premature cam failure issue has been the subject of much research by some on this forum. I have learned quite a bit from the liturally hundreds of posts I have read. Just starting a new thread after an interesting conversation I had with Geoff at Colt Cams today.

I approached Colt for a regrind cam after learning on this site about their improved lobe profiles, parkerize coating and increased performance. Geoff told me that he had done many cams for the BEW engine but not the BRM. He finally had a chance to compare the BRM to the BEW cams and made some interesting observations.

• The intake and exhaust valve lobes share common timing, lift and duration. However, the injector lobes are quite different. He explained that the valve lobes are a bad profile for hydraulic followers due to a very poor transition off the base circle to the ramp portion, pretty much insuring failure.
• The BRM cam injector lobes have a similar transition problem coupled with a very aggressive ramp. This is quite different than the injector lobe on the BEW cam which he claims is a superior design and execution.
• Major difference that makes the BEW cam "better" is the transition and gentler ramp. However, the BEW injector lobe has about 0.010" less lift.

On Geoff's recommendation, I then called Jeff at Rocket Chips to find out if this different injector lobe profile would be an issue with my RC2 tune. The answer was no problems. Jeff said that the PD injectors pump about 150% of what they actually need returning the excess. He didn't think the slight difference in lobe profile or lift would have any effect whatsoever on performance.

Long story short, this Colt BEW cam might offer a significant gain in cam longevity in the BRM engine.

That is not to say that the cam bearing and oiling modifications are not also parts of the puzzle along with oil and ZDDP. I plan on considering the bearing mods and will definitely change to M1 TDT with Cam Shield ZDDP additive as well.

Geoff is shipping me out a BEW stage II cam today. Due to my schedule, I may not be able to get the change done for a couple weeks but will post updates as the project progresses.

My appologies for any redundant info here if this has been done before. Just that Geoff had only just figured out this difference in the last day or two. I am emailing a link to this thread to Geoff. He said he would keep an eye on it and be happy to answer any questions.

Wow that is pretty sweet. That BEW Stage II Colt cam is what I'm saving up for.

Are you getting the black lifters?

Congrats!!

Good to know there is finally some concrete info on the differences between BEW and BRM cams.

If, or more accurately, when I need a cam, I will definitely go with a Colt BEW regrind.

The test mule 2006 TDI that I went through got some tweaking done to the valve lobes and of the changes, the most important was to relieve that nasty transition from base circle to ramp.

Parkerize the lifters and the cam, use a good break in oil and assembly/blueprint process, checking bearing bore alignment and bore concentricity, camshaft straightness front to back and correct as needed, change and match the valve springs, and carefully set closed height of the valves, and don't let the thing idle at it's first startup for at least 30 minutes.

Yes, the black followers and new bearings will be part of the repair.

Rod Bearing said:

The test mule 2006 TDI that I went through got some tweaking done to the valve lobes and of the changes, the most important was to relieve that nasty transition from base circle to ramp.

Parkerize the lifters and the cam, use a good break in oil and assembly/blueprint process, checking bearing bore alignment and bore concentricity, camshaft straightness front to back and correct as needed, change and match the valve springs, and carefully set closed height of the valves, and don't let the thing idle at it's first startup for at least 30 minutes.

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Rod Bearing, any follow up on the BRM that you built with the improved cam lobe profiles and blueprinting efforts? Did you find any significant issues in terms of cam bore concentricity or sizing? Mileage and results so far?

Will definitely follow proper cam break in procedures, lots of moly lube, extra ZDDP, maintain 2000 RPM give or take in the shop for 20-30 minutes on initial start-up then verify cam timing with VCDS. I also like to shorten up the first OCI with new parts like this.

Thanks for posting this A5INKY, its made me decide that I want a colt reground cam if time comes to do this again.

A5INKY said:

Will definitely follow proper cam break in procedures, lots of moly lube, extra ZDDP, maintain 2000 RPM give or take in the shop for 20-30 minutes on initial start-up then verify cam timing with VCDS. I also like to shorten up the first OCI with new parts like this.

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I don't know if its been debated somewhere, if so I have lost track. But I do distinctly remember jasonTDI saying something about how he idles the car for break-in, I found it very interesting because that's how I broke in my cams back in September. Revving just puts more stress on the cam system.

But since colt recommends it, I suppose to each his own.

A5INKY said:

Yes, the black followers and new bearings will be part of the repair.


Rod Bearing, any follow up on the BRM that you built with the improved cam lobe profiles and blueprinting efforts? Did you find any significant issues in terms of cam bore concentricity or sizing? Mileage and results so far?

Will definitely follow proper cam break in procedures, lots of moly lube, extra ZDDP, maintain 2000 RPM give or take in the shop for 20-30 minutes on initial start-up then verify cam timing with VCDS. I also like to shorten up the first OCI with new parts like this.

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The two issues that concerned me were the installed valve heights as they measured at teardown and the cam bearing bores. The head got some very fine work done by a longtime friend who does all my racing stuff. Align hone the cam bores and properly done valve job. I also noted the fit of the cam followers/lifters in their bores left some room for improvement. I've built tons of race engines with solid lifter cams and I always zap them with a 2-3000 RPM 30 minute no load break in from the first puff of smoke. Others prefer to idle them. I don't think that delivers enough oil flow to new cam bearings and surface contact points.

Last look at the cam was some time ago, and it still had some of the parkerizing on the lobes, so it was broken in nicely and doing very well. The car has almost 40,000 miles on that cam right now. I let an employee drive the car as her own. She never warms it up and it hits the highway every day for a 45 mile trip to work. I used Joe Gibbs BR break in oil and their assembly grease. I run Delvac 1300 Super 15w40 DINO oil in it.

The cam lost a bit of lift and no doubt a tad bit of duration with the re-profiling but I can't feel any difference.

I suspect the cam will run a long life judging on oil analysis and how the oil looks at each change.

Just curious, why parkerizing? Isn't that just an anti rusting covering? It eventually will wear off, and I am unaware of any extra protection it would give. It may hold onto oil a little better then bare metal.

Jnitrofish said:

I don't know if its been debated somewhere, if so I have lost track. But I do distinctly remember jasonTDI saying something about how he idles the car for break-in, I found it very interesting because that's how I broke in my cams back in September. Revving just puts more stress on the cam system.

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Exactly. If RPM rise then there's demand for more fuel resulting in more pressure request by the injectors. ~3000 RPM is nearly 75% of power by RPM range.

I also idled mine as a break-in.

I think the injector compresses the same amount of fuel regardless of how much goes out the nozzle. And the return spring rate is the same regardless of rpm.

2footbraker said:

I think the injector compresses the same amount of fuel regardless of how much goes out the nozzle. And the return spring rate is the same regardless of rpm.

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So we are at 27000 psi at idle too??? No wonder these cams are failing so often.

I have built a few engines of various kinds and worked with a couple of automotive machinists and engine builders that have all given the same recommendation for cam break-in. I honestly can't authoritatively say exactly why to run them in at a higher RPM and no load. It is just what I have always been told and done. When Geoff at Colt gave the same recommendation it did not occur to me to ask why. Intuitively I would agree with Rod Bearing about the oil supply being greater considering the nature of automotive oil pumps and systems. I have never experienced an engine oil pump that functions at it's full flow at idle.

I did question Geoff about cam surface hardness and he indicated that hardness is not nearly as critical as finish and lobe design (getting rid of those nasty transitions). I would assume that Parkerizing is better for holding lubrication. The fact the Geoff doesn't clean up the injector lobes until after Parkerizing (so that the finish is removed) would support this reasoning. The injectors have roller followers and he said that Parkerizing is not appropriate for rollers.

I am no expert on the PD engine's injection system, but intuitively it would seem that the injector would need to see a relatively constant pressure regardless of load or RPM. By making the pressure a constant I would think that the ECU would be able to more accurately control the injection events, similar to typical gasser engine EFI strategy. If that is the case, injector induced load on the cam would also be relatively constant and not dependent on RPM.

If I am off on any of this, I would like to learn why.

A5INKY said:

If I am off on any of this, I would like to learn why.

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Me too.

Discussing not the fuel supply pressure to the injector, but the actual force that the camshaft must apply to the rocker (and it to the injector). To me it seems to be physics. Say for example at idle you are injecting X amount of fuel over a time span of Y through a Z sized injector, when you hit the accelerator the car would inject X^2 over (1/2)Y through Z. Pressure required to accomplish that feat increases.

I think you are correct on that the supply of fuel to the injector needs to be consistent for the computer to give an accurate amount of fuel to the unit injectors to begin with, but then the force to inject said fuel is on the cam.

As for the oil pump, I think the BRM engines got a beefier oil pump than the BEW. Sure while it might not provide its full flow at idle, it provides an adequate flow of oil with the engine in a state of minimal load.

A5INKY said:

I have built a few engines of various kinds and worked with a couple of automotive machinists and engine builders that have all given the same recommendation for cam break-in.

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How many of them had flat tappet + roller rocker controlling injectors cams?

Jnitrofish said:

So we are at 27000 psi at idle too??? No wonder these cams are failing so often.

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Yes. It only varies about 700 psi from idle to full fueling. The same amount of fuel is compressed regardless of requested fuel. What changes is when the solenoid opens to relieve the pressure. That timing is what determines injection quantity.

Therefore, running at idle will not decrease the cam load.

2footbraker said:

Yes. It only varies about 700 psi from idle to full fueling. The same amount of fuel is compressed regardless of requested fuel. What changes is when the solenoid opens to relieve the pressure. That timing is what determines injection quantity.

Therefore, running at idle will not decrease the cam load.

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That contradicts. You prove me right and you still say I'm wrong. So now I have to go research this better (and im supposed to be researching Hamlet for college, unit injectors are much more fun ).

And the results are...you are correct! I completely forgot that this is a high pressure injector to begin with, requiring upwards of 5000psi to lift the pin to start injection into the cylinder, and then continuing to build pressure rapidly due to the nozzles being so small and volume of fuel compressed being greater than I originally thought.

The change in injection pressure from idle to WOT is minimal on the grand scale of things. Unless the volume of fuel required for idle can be injected before the injector reaches its peak pressure. (?) But surely anything beyond idle should be little to no difference in injection pressure.

So again, as break-in goes, to each his own, I'm glad we could at least make a more informed decision on this matter.

I have already sent Colt an email through their contact form, hope to hear back.

hid3 said:

How many of them had flat tappet + roller rocker controlling injectors cams?

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None, all have been flat hydraulic or solid tappet. Please expand on why you think the cam should be run in at idle for a combo cam like ours.

The issue seems to be oiling of the flat tappet, intake and exhaust valve lobes similar to what I have built before. The flat tappet portion is what is failing on BRM cams, not so much the roller injector lobes. Since the roller lobes are not wearing prematurely, injector induced forces on the cam do not seem to be dependent on RPM, and the cam specialist (Geoff at Colt) recommends a higher RPM/no load run in, I am leaning toward that procedure.

If you have information that contradicts this, please share. I want to do this right the first time and am open to better ideas.

A5INKY said:

None, all have been flat hydraulic or solid tappet. Please expand on why you think the cam should be run in at idle for a combo cam like ours.

The issue seems to be oiling of the flat tappet, intake and exhaust valve lobes similar to what I have built before. The flat tappet portion is what is failing on BRM cams, not so much the roller injector lobes. Since the roller lobes are not wearing prematurely, injector induced forces on the cam do not seem to be dependent on RPM, and the cam specialist (Geoff at Colt) recommends a higher RPM/no load run in, I am leaning toward that procedure.

If you have information that contradicts this, please share. I want to do this right the first time and am open to better ideas.

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Firstly, I don't have any scientific info on this, just my thoughts which are now being discussed in this thread (injection pressure).

So as for idle: I still think that at no power/idle situation the injectors require less pressure so it's less pressure on the cam (downwards). If you bump the throttle the demand of the pressure (on the cam, downwards) increases. This might cover the oiling holes in cam bearings causing oil starvation situation.

Just ordered assembly grease and break-in oil from Joe Gibbs Racing. Here is a link to their cam break-in guide:

http://www.joegibbsracingoil.com/trainingcenter/tech/cambreakin.html

Another vote for 2000 RPM no load for 30 minutes...

2000-ish rpm for several minutes (30 may be overkill) makes sense. Keep in mind that the cam loading condition doesn't much care how much load is on the engine. 2000 rpm consisting of running down the road with the cruise control set will do just as well.

GoFaster said:

2000-ish rpm for several minutes (30 may be overkill) makes sense. Keep in mind that the cam loading condition doesn't much care how much load is on the engine. 2000 rpm consisting of running down the road with the cruise control set will do just as well.

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Wow, this is what I've almost done. After having my cam replaced, I started the car (it was winter outside) and idled for about 20-25 minutes. After that I gently took off for some highway traffic. I was driving steadily at 1750-1800 RPM with minimal acceleration. I drove around 180 miles this style.

hid3 said:

Wow, this is what I've almost done. After having my cam replaced, I started the car (it was winter outside) and idled for about 20-25 minutes. After that I gently took off for some highway traffic. I was driving steadily at 1750-1800 RPM with minimal acceleration. I drove around 180 miles this style.

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To each his own I guess, but IMO your method is textbook on how NOT to break in a flat tappet cam. Cold weather. First life 30 mins idling. Drive at low RPM.

Yeah, but what could I do? Warm up the weather? It wasn't that cold, maybe around -5*C. We turned over the engine a few times by hand, that should have ensured at least minimal amount of oil where it supposed to be during any startup...

I know, I know. If I'd be replacing my cam right now, I'd be doing much things differently.

What is the cost of a new BEW stage 2 cam? Do you still send Colt the BRM as a core? I am trying to weigh the pro's and cons of a Colt cam vs. a stock cam. If the BEW lasts longer it would be a plus over the BRM. Why not just get a stock BEW cam and place it in the BRM engine? I don't know if the slight increase in horsepower is worth the extra cost of a Stage 2 vs. stock.(For my use.) Thanks for letting me think out loud!

From what I have learned and conversations with Geoff at Colt, I would not go back with an OEM cam at this point due to the lobe design issue, not when an alternative exists. Colt offers a stock replacement version that has the design corrections and parkerize coating for not much more than an OEM cam from one of the vendors that frequent this forum. True, the BEW design might be an improvement over the BRM unit. But the int/ex valve lobes are still not the best design for longevity.

This is not exactly proven IMHO. But it makes sense to me and with the narrow cam lobes and other design issues of the PD engines, the solution just might be a combination of factors.

For a couple of hundred dollars, the gains reported by going stage II look like a good return on investment when the cam is getting replaced anyway. We shall see...

Will you post some pics of a reworked cam? Thanks.

Geoff and I are in conversation for bringing in cams. I certainly am not arguing that he's got something going and he's looked at my improvements and sees the reasoning in them.

I think the biggest advantage for state-side buyers will be no big shipping fees or duty coming across the border. We just need to figure out what needs to be stocked.

If there are any particular suggestions besides the BEW/ BRM cams, I'm all ears. PM me.

This basically confirms what I and others suspected... that the solution is to replace the BRM cam with a BEW cam. That was a factory configuration on some european PD models I believe, par posts from foreigners on here.

So a poor profile on the injector lobe is now coming up as an issue...? What else could they have done? lol

heh, this whole thing just becomes a puzzling mess every time I think about it. For example, my current quandary; I thought that the injector lobe was just something was just to help the bearings and yet I cant exactly say if its effecting the lifters, and if its significant, except that the BEW engines don't fail lifters as often...

• The intake and exhaust valve lobes share common timing, lift and duration. However, the injector lobes are quite different. He explained that the valve lobes are a bad profile for hydraulic followers due to a very poor transition off the base circle to the ramp portion, pretty much insuring failure.
• The BRM cam injector lobes have a similar transition problem coupled with a very aggressive ramp. This is quite different than the injector lobe on the BEW cam which he claims is a superior design and execution.

Click to expand...

So if that's all true, and the BEW engines have the same valve/lifter lobes, with only a mild difference in injector lift/ramp, then why are the BRM's failing more often? Is that extra lift shoving the cam deeper into the head?