DD Cam and Donnelly Head

[cumminsgetme]

My brother and I just got finished installing his new DD cam and Donnelly ported head. He saw roughly 400 deg drop in egt and about 8psi loss in boost. He didn't think the truck was much stronger (however we didn't anticipate it to be much stronger), but egt's were way down. We didn't have much time to test because he was in a hurry to get back to Las Vegas, however I'm curious to see how he likes it over the next few weeks. I'll be able to give some more solid numbers in the next few days.



-Cord

 

[Jim Fulmer]

He saw roughly 400 deg drop in egt and about 8psi loss in boost Sounds like he needs more fuel now



Good to see you back on the board Cord!



Jim

 

[Don M]

Yeah Cord I saw an EGT drop too with just the head. Still saving my greenstamps for the camshaft.

Oh, I lost a few pounds of boost too. The cool things is... . now the air is getting into the engine not bottled up in the manifold.



Don~



good to see ya back again

 

[Strick-9]

I'm still amazed at that. 400° is a HUGE deal.



Jim, maybe someday Cord will share with you the story about how his truck broke down on us (more than once) and his brother had to come pull us home. When you are sitting behind that truck, you would never say it needs more fuel.



We were being pulled by a 15' chain and there were times when the smoke was so thick, we couldn't see the truck in front of us. hehe. That was hilarious.



370's, a #0, and he could push his HX-40 to 43-44 psi of boost.



Amazing that DD's cam is that good. Simply amazing.



-Chris

 

[HoleshotHolset]

So I guess that DD's cam is no longer an in-house install ONLY type of thing?



Matt

 

[cumminsgetme]

It was tough for me to accept 400deg... ... like Chris said, that's huge. I think a lot of people kid themselves of the performance gained simply in an attempt to justify the money spent. We have thrown money at parts trying to lower egt's yet never seem to gain more than 50-75deg. I still want to personally drive the truck and convince myself that it is an actual 400deg drop. My brother is afraid of breaking things due to the fact that it's a 4wd ext cab dually with ***** piled to the top of the bed (literally..... Chris can comment). I'll try to steal the keys in the next few days to put it through my own tests!!



JFulmer-



I slipped timing twice after installing the new pump. Chris was with me the second time (the first time I had a 3 mile walk back to the house only to find Chris and another buddy laid up on the couch eating carne asada ). We get the chain hooked up and before I can close my door we're in a cloud of black smoke running about 30mph. Once I finally get my truck under control he hits 5th and lays in it (the whole time our vision is blocked due to the smoke)... ... ... well, he misses the street because we're running 70... . and of course blames it on me. We get turned back around (as fast as possible with two trucks and a chain) and head back to the street HE missed. Only he doesn't slow down... ..... he whips the wheel and sling shots us around the corner at about 40mph (if Chris has finally managed to get the rest of the seat dug out of his a$$ he'll tell you it was fast!!). I don't think I have ever been so glad to get unhooked from a chain in all my life!!



Thanks for bringing that up Chris..... I'm definately going to steal his keys now..... I'll have some test results for you guys in a day or two.



-Cord

 

[Todd T]

it doesnt take much to pull and cam and spec it out yourself.



how long did they think that little signed waiver would keep them safe anyway? it just detours business, if you asked me. by the time i shipped my truck to LV and back i could have a couple custom ground cams on the shelf just my opinion though.

 

[cumminsgetme]

HoleShot-



The cam is still an in house install. I simply did the grunt of the work. Joe was near by during the install. DD trusted Joe to supervise the install to ensure that the cam wasn't copied.



-Cord

 

[KatDiesel]

Originally posted by Todd T

how long did they think that little signed waiver would keep them safe anyway?

Who told you you had to sign a waiver? I wasn't asked to do anything of the sort.

 

[Jim Fulmer]

Cord, that's what I call a good story, puts a different twist on smoking out a tailgater



Jim

 

[Todd T]

deep breath....here goes...

it really doesn’t matter if YOU had to sign anything or not. Maybe they didn’t want to loose you to the competition with you being somewhat of pack leader and in the spotlight? (not a dig, just an observation. You deserve to be where you’re at and have come a long way to get there. ) it's the fact that this cam is taunted around here as a cure all for the horsepower and EGT woes. But then it is not marketed in a practical manner. that makes it not worth taunting at all. It just furthers the gap between customers(potential or otherwise) and vendors. Pickup a Summit Racing catalog and look at cams. The specs are all right there for you to see. and lone behold, all the different manufacturers have managed to still stay in business with their competition knowing what is being sold. Maybe it’s because they have good products AND good customer satisfaction. More so of the latter.



And don’t give me the “you just have to ask them and they will tell you line” its more than that. it’s the principle behind the idea that they cannot allow something like a camshaft grind to come between them and their competition. so the consumer has to suffer because of it. well, THIS consumer doesn’t allow the vendor to mandate to him, how and when he spends his money. What kind of CUSTOMER loyalty is that? that just makes me want to get out a saw and cut the bottom of someone’s podium out. with one phone call I can have my hands on an older version of that cam and it wouldn’t be far from there, that I could come up with the current one(not that I intend to, just making a point). But just stop and think of the guys who cant afford to run their truck to Nevada that went down the street and spent their money somewhere else in the meantime. I know a few. It makes me think the profit margin is enough they dont have to care. I hate getting jerked around, I really do…



Off my soap box now, flame away.

Todd

 

[Sled Puller]

Holy cow!

ToddT speaks his mind!



Kwik Kat, lock the thread! Lock the thread!

 

[Doubleclutch]

Sounds like we need a DD-East, and a DD-West, and maybe a DD-in middle... Valid points Todd makes. The drive is worth it though! With a DD cam, J. D. ported head, and ATS manifold- it kinda sounds like headders... smooth

 

[Boldt's Wagon]

You might be a little cautious in thinking you have a full 400 degree drop in the combustion chamber. Most of this drop is probably due to more overlap with the intake and exhaust valve opening. With the overlap, air flows directly through both valves and cools the exhaust gas. The maximum temperature the piston has seen may be the same as with the stock cam.



Two cycle diesels typically used 30-40 % excess air to flow through the combustion chamber to help cool the pistons. Two cycle diesels have been known to melt pistons also.

 

[Don M]

Originally posted by Boldt's Wagon

You might be a little cautious in thinking you have a full 400 degree drop in the combustion chamber. Most of this drop is probably due to more overlap with the intake and exhaust valve opening. With the overlap, air flows directly through both valves and cools the exhaust gas. The maximum temperature the piston has seen may be the same as with the stock cam.



Two cycle diesels typically used 30-40 % excess air to flow through the combustion chamber to help cool the pistons. Two cycle diesels have been known to melt pistons also.

They are measuring the drop in the manifold. Not the combustion chamber. The scenerio you speak about would only raise the manifold temps higher. Overfueled engines dont need extra air injected into the exhaust side at all.



Don~

 

[LSMITH]

I think you are being a bit quick and presumptuous Don. Boldt makes a good point. Do you have evidence to refute his point?

 

[Don M]

Originally posted by LSMITH

I think you are being a bit quick and presumptuous Don. Boldt makes a good point. Do you have evidence to refute his point?

Of course I do LSmith. I cant speak about the DD cam (cuz I dont know anything about it) and dont want to get into camshaft design, but I will tell you why you dont have/want overlap on a turbo engine.

Most of it has to do with turbine housing size and exhaust back pressure. We all want spool-up and so most of us have a small turbine housing that when at full power has a higher drive pressure than the boost level is. What does this mean?

For another clue... What happens when you add oxygen or more air to an exhaust stream that is ladden with unburned fuel?



I think Bolt has a good point about not doing this for a performance cam. The engines he deals with are probably not fueled to the hilt like the hot-rod diesels we run though. The drive pressures are not as high as ours are either.



Don~

 

[msmtd]

ON Edit;



Chad, those comments added nothing to the context of the subject other than to antagonize other members. which is not tolerated here.



Todd- Moderator

 

[LSMITH]

Don, you said you don't know anything about the profile of the DD cam, yet you say you know what it is? I asked for evidence. the overlap portion is small and it can push some heat out, the temp in the manifold will drop as the air cannot take on much heat in a short time.



If you are right what is the drive pressure in the instance we are describing and what is the boost pressure?

 

[Jim Fulmer]

Don, I know very little about these trucks, but has anyone ever measured back pressure on the exhaust. I do know that some of the gasser guys fight this and they say that equal back pressure to boost is optimum but it never happens, some have measured 60lbs of back pressure and usually ends up as a blown head gasket... ... ... guess I need to ask them more questions.



Jim