Delta 202 cam no good?

[FellowTraveler]

I had a cam ground locally ,but it had some overlap that caused a major drive-ability problem. It had tremendous spoolup power,but the engine would run off of it's own exhaust,and clatter like crazy,it didn't matter were I set the injection timing.

Had found this out with wild grind N/A cam &/lot's of overlap in a turbo gas motor without clatter it was crazy powerful but short lived w/fuel igniting in turbine and exhaust.

 

[Jorge6.5]

I don't understand why non of these vendors post cam specs. How is one gonna know it's what they want with out at least knowing some of the numbers?

The specs are readily available if your buying any cam for a SBC for example. It's so people know what they are getting and can decide if its gonna work for them or not.

I don't understand why these vendors are keeping secrets and then have the nerve to charge outrages prices for said parts.

Sorry for the rant, just my thoughts. I hope the 202 cam works out for you.

 

[FellowTraveler]

I don't understand why non of these vendors post cam specs. How is one gonna know it's what they want with out at least knowing some of the numbers?

The specs are readily available if your buying any cam for a SBC for example. It's so people know what they are getting and can decide if its gonna work for them or not.

I don't understand why these vendors are keeping secrets and then have the nerve to charge outrages prices for said parts.

Sorry for the rant, just my thoughts. I hope the 202 cam works out for you.

You are a million % right this is the standing argument and the vendors still resist like it's a trade secret no one should know but them but they still think you should buy it form them anyway "arrogant" comes to mind.

 

[devildogadam]

Very true Jorge & traveler. But the mentioned vendor is that way with all of his products. Take his "hot rod" injection pump for example. He will not release any specs on the pump. But if I wanted to buy a hot rod p7100 for a Cummins those vendors would say, this is our pump it flows this much at this rpm. The plungers are this big and it comes with this long of a warranty. Same with his turbos and all of his products. So why is he so unwilling to tell you what you are buying.

 

[devildogadam]

Sorry for beating that horse after it was already dead. Sometimes I get carried away.

 

[DieselCash]

He does not want to share his specs. He never has, he never will. He wants all the money to himself. He does not want to share.

Only way to stop it. Stop buying his products. Stop using, sharing, saying, or promoting him or his products. Bankrupt him.

Our, purchase his product and spec it out yourself. Then post it all over the internet.

I have never purchased any of his products. I feel his prices are way to high.

 

[turbovanman]

All the stock cams are the same, including the P400, IIRC.

I know why vendors don't release the specs and sorry, but you can't blame them. Too much copying going on, it happened so many times in the Turbo Dodge community. I had a RV cam made for a 3.0L turbo V6, posted the specs, a person bought one, turned out he's a 3.0L guru, had Delta copy my cam and now he sells them as his own.

I know Colt Cams locally makes a turbo cam for us but its costly and I am not willing to take the risk even though he's made me cams for my Caravan and other customers and they worked better than I expected. If I did try one, my biggest issue is I am building a GEP, so everything is different,

 

[FellowTraveler]

So, when buying a bumpstick for the 6.5td chest-waders are required too?

I'd stay clear of anyone who sells performance parts w/o offering the specs so I can make an informed decision.

 

[Will L.]

I just grabbed this randomly online in about 10 seconds for an old school sbc.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1258&sb=2

Any cam I ever bought, for any engine, from any supplier, I was always given this info. Why is the 6.5 so magically secrative? Because of its overwhelming power to weight ratio? Lol.

Seriously, deck the heads, Now realize we are dealing with a 4-5k rpm engine at best so figure valve float useing roller rocker arms. You can get 1.5 or 1.6 arms. Pick one, doesn't matter right? Now knowing lift determines your arm and valve to piston clearance. Kind of important, no? What's the real purpose of those thicker head gaskets?

How's about figuring the valve spring tension - you need to know duration and angle point of open and close to know scavange over lap (or amount in negative In Our case) to keep from either floating your valves, or throwing away power with too much drag on cam and possibly wiping out cam lobes and setting injection timing based on the scavange event timing, right?

Why are you supposed to work your heads and get the flow
Before ordering a cam? Because if you can not unshroud the valves all the way- lets say your stuck with .010 on the intakes, but you got all of it on the exhaust. To get proper flow you need the cam to lift the extra .010 to flow proper. Now you know you have to cut that extra recess in the piston tops. So in a 6.5 all the options are not there because this is not a performance engine. Nothing in this engine stands the real abuse of high perf.

So I get it that someone doesn't want to do a bunch of research and not get paid for it, if that's what they are after. But if I tell you I have these killer kit that add 100 hp and 150 torque, but can't tell you anything why would you buy it for you 6.5? Yeah it's a propane bottle running at 150. Poof here's your power and poof there goes you crankshaft on the ground, and through your fender, and some over there by that tree. To not tell someone basic cam specs for them to know what impact it will make on the engine is stupid. Ask any 2nd year highschool auto shop class if matching a cam to your build is important.

To tell me the greatest thing is 4 different cam lobes to get the most out of my side mount turbo, then turn around and say side mount doesn't matter and neither does boost vs ambient? Total sales pitch bs.
He done a lot for the 6.5 yes, but remember he claims to have invented the rear hose cooler head kit (thought up by many a person who ever had one over heat and kill a #8 hole). Why doesn't he sell it now? Oh yeah, cuz even GM shot that thing out of the water and proved it did more damage than good.

If someone can not show you the specs, or show you the dyno, I have to question it deeply. The race truck and the business to hand in hand.

I worked for Lynn Goodfellow when he was building his ride that set the record for his class. Its all money. If Bill wants to sell parts for an oddball engine, a claim to fame is the best advertisement and excuse for saying "trust me"

 

[FellowTraveler]

For now I'm very happy w/my 6.5td so no new, exotic or mystery bumpstick for me!

 

[great white]

Very true Jorge & traveler. But the mentioned vendor is that way with all of his products. Take his "hot rod" injection pump for example. He will not release any specs on the pump. But if I wanted to buy a hot rod p7100 for a Cummins those vendors would say, this is our pump it flows this much at this rpm. The plungers are this big and it comes with this long of a warranty. Same with his turbos and all of his products. So why is he so unwilling to tell you what you are buying.

Honestly, the specs on a DS4 are pretty much irrelevant anyways. Without some VERY involved programming work in the ECM, it's hard coded to max out at 79.7 mm3:

I only know 3 people who have the ability to break that limit in the coding and 2 of them don't sell anything, it's all private/personal work. The third can't be bothered anymore as there's not enough money in it. Pop pressures, plungers or whatever: all pointless with the software limit in place.And even then, just because you are commanding it over 79.7 mm3 that doesn't mean you are actually getting it....

A DB2 is a different story though. No software to overcome, just mechanical limits. I don't work in those, so I don't have any specific info on them.

 

[great white]

Let me take a shot at trying to give some understanding of cam choice in a forced induction engine in as short and simple a way as possible.

Lift is less important than lobe separation angles (LSA) on a FIE. Lobe duration has a more salient effect than lift, but it also starts interacting with LSA to change overlap when it gets bigger (which can be a negative thing as we will see further on).

The other problem you are facing in a 6.5 is inherent to the design, but I’m getting a little ahead of myself.

Lift is limited in a 6.5 by a couple things, but mainly the geometry (IE: valve clearance). Lift is also not as important because you’re dealing with more than 1 atmosphere trying to rush into the cylinder. It’s not irrelevant, but not as big of a gain. Lobe duration is more effective than lift to get more of that 1+ atmosphere in that chamber.

LSA is directly related to the amount of pressure in the exhaust. Basically, more pressure at the exhaust port means more overlap means more reversion in the exhaust flow.

Yeah, that’s really nice but what the heck does that mean?

If you have too much overlap (say somewhere around 108-109 degrees LSA, keeping in mind overlap is a function of both LSA and lobe duration) in a turbo engine (normally in the 112+ degree range), you end up with exhaust trying to cram it’s way back into the combustion chamber while the exhaust valve is open too long. You can think of it as the opposite of scavenging effects in a NA engine.

The 6.5 itself and its exhaust system are another big issue here. The turbo is naturally a restriction, but it has to be there or we wouldn't be having this discussion. The exhaust is another restriction, both in it's design and just by the nature of friction in the pipes. You can free it up with a more modern turbo (increased efficiency) and a free flowing exhaust. Then, in theory, you could tighten up the LSA in an old 6.5

But there’s another gotcha in the 6.5 to re-jigged LSA: High compression and head design. Tightening up the LSA means opening the exhaust valve sooner. The danger of this is possible bent pushrods.

Say what? How can LSA bend pushrods if it clears the piston?!?

Well, the valve face surface pushing against high combustion pressures (remember we’re starting at 21:1 here) is quite large relative to the rest of the valve train components. This means increased pressure in the valve train. Everything in the valve train is relatively robust and supported in guides and bores, except…..the pushrods. When push comes to shove, the rods loose and deflect. Believe it or not, I've seen it before. We all thought there was something binding somewhere bu there were no obvious rubs or binding when turned over by hand. Had us all bedeviled. Swapped in an OEM cam (not a 6.5). Bingo, pushrod problems went away and the engine made darned near the same output. Well, as much as we could run the engine on the dyno before it roached a pushrod that is...

It’s all kind of moot anyways. The 6.5 heads are a pretty poor design by modern standards. heck, they're even a pretty poor design for 1982. Easy and cheap to produce, but low expectations in the power dept. Keep in mind GM built these to be “penny pinchers” in both running and production costs (and it shows).

And even if you do manage to overcome all those tidbits and end up with a cam with tons of overlap that works, the prechamber design is going to throttle you right back to crap gains at best. Open ‘em up and you lose efficiency which starts to cost you power as well.

It’s just innate to the design…runs great on crap fuel, low injection pressures and met noise and emissions in it's day, but makes low power. Only way to get around the basic design is to yank it and drop in something better from the start, which is what GM did with the LB7.

Now, assuming all this didn’t deter you and you still wanted to design a cam that worked better, you’re going to get in pretty deep. You would have to redesign the combustion chamber, exhaust manifolds, turbo and exhaust to match it. I would suspect this is why people selling “cams” for a 6.5 TD are reluctant to public specs: those that know would read them and know they aren’t that much different than OEM. They can’t be unless you redesign the whole system. Releasing specs and them being close to OEM would be “letting the cat out of the bag” as it were and any chance at profit would be gone like a fart in the wind.

Unlike a NA engine, it’s not as simple on a forced induction engine as swapping cams and enjoying more HP at the range you want…..a cam is just knocking over the first domino in a very expensive run.

And we still haven't even touched on how cam selection is effected by vehicle weight, gearing, torque converter, etc.....toss in how it effects prechamber behaviors and the characteristics of the diesel cycle (ie: ignition delay, fixed burn times, etc) and it gets really murky really fast. This is a lot of why DI is easier to build more power, you can literally just cram in more air and fuel to make more power (until it pops, then just build it stronger).



I kind of went back and forth there a little bit, I pulled that off the top of my head and I haven’t messed with cam geometry or abstract combustion theory in a while. Please excuse any errors.

 

[turbovanman]

I thought there were some cam programs where you could play with specs and see what works?

Great insight, thanks.

 

[great white]

I thought there were some cam programs where you could play with specs and see what works?

Great insight, thanks.

Lots of 'em out on the 'net....most are set up for NA though. Estimating for forced induction isn't easy...

 

[EWC]

I did post the specs for the Crane cam as I was told I was only the second person to get the regrind . First was for a boat and Crane had no way to get ahold of the owner . Right now the engine is assembled and sitting on the stand . I was happy to find another cam for the 6.2 as this was a while ago and the only one I had heard of . I primed it and could turn the engine over and that's as far as I went . Ported heads , gear drive and yes it had to be moved when I degreed it . Should run pretty good with the Banks when/if I get it running .

 

[devildogadam]

Thank you for that explanation. Very well put together for a seat of the pants answer. But the main problem I saw was the fact that their main selling point is a cam with different lobe profiles for different cylinder. That simply won't work. You would have different air to fuel ratios in cylinder as the motor was trying to run. There is no way this could smooth it out or make more power. Now different profiles for intake and exhaust make perfect sense but what they said as a sales pitch just plain won't work. Keeping trade secrets is one thing, but blowing smoke is uncalled for.

 

[great white]

Actually, the theory is not total BS. Several grinders have/do offer these types of cams. But to my knowledge, they're all for NA engines.

It has to do with unequal intake runner lengths, turns in the intake path in the manifold and the cumulative effect on VE.

Theory is (IIRC, been a long time since I looked at it) the lower VE in a specific cylinder resultant from the intake tract, the more duration required and the higher VE runners need less duration.

Now, VE is less effected in a forced induction engine, but the effect is there. But there could be some gains if managed properly in the cam profile.

As to whether the people selling cams under this theory have got the profiles correct.......dunno. It would take some fairly extensive dyno work on each grind. That's why I would tend to take the larger companies who have the R&D budget more at their word than smaller shops.

BS in theory?

Nope.

BS in execution?

Maybe.....

 

[great white]

Designs like Banks' Boss Hoss manifold get around all this camshaft buffoonery by using equal length runners:

(there might be at least one 6.5 running around out there with this style intake )

This makes the "multigrind" cam useless, maybe even detrimental.Dunno, you'd have to dyno one to know for sure.

Here's a few quick images that might give a little more clarity on the subject:

Of note: those are for NA carb and FI engines and equal length runner intake manifold make the "multigrind" useless on them too.

And there's still the "did the cam grinder get it right" factor to consider.....

 

[devildogadam]

I do see how this does work on a na motor with vacuum. But as soon as pressure is introduced it becomes pointless. I don't think Mr. Heath would sell something without extensive research, but this still scares me on a forced induction engine.

 

[great white]

There is some validity to its employment on a 6.5 TD since it uses unequal length runners and a twisting low rise manifold.

While the VE of a forced engine is less affecedt by this, it is still affected.

Therefore, validity in concept.

In execution I would suspect there is fairly minimal gains to be had. Gains to be sure, but I wouldn't expect them to be very noticeable. Again, you'd have to get it on a dyno and do the work to find out.

Its up to the consumer to decide if that potential gain is worth spending the cash or not.

I would not.

There are better places to spend your time and money for gains in this old design.