W350 Crew Cab - The ultimate first gen - Pics and history

[AH64ID]

Not following... ...

I don't 100% why, but I have heard that the performance cam's don't exhaust brake as well as the stock cam. I beleive it has to do with the duration and overlap from intake to exhaust. In an effort to retain as much braking as possible I went with the Stage 1 cam. I do know that rpm for rpm the Stage 1 has lower backpressure than the stock cam. The truck feels about the same, but there is lower pressure until about 2500 rpms. I also noticed that my IAT's will slightly increase under EB use now, where the never did before. . tells me the overlap causes a little back flow, very little the IAT's only go up 6-10* F.



Just what I heard, and from what I have seen I could see the backpressure decreasing even more with a larger profile cam.

 

[RSchwarzli]

Guess it makes sense.



Guess I will see!

 

[HHhuntitall]

Hmm, I'm not convinced. It can only flow so much air through the engine... . with the fuel cut, you're only filling the cylinder, which is the same amount of volume per stroke cycle... ... then you're restricting the release of that air through the exhaust valve by the brake to create resistance against the piston, which resists the crank, drivetrain, etc. I wouldn't think cam overlap would affect braking resistance that much, unless the intake valve were opening before the piston reached bottom center. IF it did that, it wouldn't run very well. While that cam opens quite a bit earlier for air flow, I wouldn't think it would effect the exhaust cycle..... exhaust opens at the same time on both..... There might be a small amount more air in the cylinder due to a longer opening time, but I don't think without boost it would be effectual on the exhaust braking effect... . Hmmmmm... . Robert, go work on your truck so we can all know firsthand!!!!

 

[RSchwarzli]

Hmm, I'm not convinced. It can only flow so much air through the engine... . with the fuel cut, you're only filling the cylinder, which is the same amount of volume per stroke cycle... ... then you're restricting the release of that air through the exhaust valve by the brake to create resistance against the piston, which resists the crank, drivetrain, etc. I wouldn't think cam overlap would affect braking resistance that much, unless the intake valve were opening before the piston reached bottom center. IF it did that, it wouldn't run very well. While that cam opens quite a bit earlier for air flow, I wouldn't think it would effect the exhaust cycle..... exhaust opens at the same time on both..... There might be a small amount more air in the cylinder due to a longer opening time, but I don't think without boost it would be effectual on the exhaust braking effect... .

That was along the lines of what I was thinking...

Hmmmmm... . Robert, go work on your truck so we can all know firsthand!!!!

Nice! :-laf

 

[AH64ID]

Hmm, I'm not convinced. It can only flow so much air through the engine... . with the fuel cut, you're only filling the cylinder, which is the same amount of volume per stroke cycle... ... then you're restricting the release of that air through the exhaust valve by the brake to create resistance against the piston, which resists the crank, drivetrain, etc. I wouldn't think cam overlap would affect braking resistance that much, unless the intake valve were opening before the piston reached bottom center. IF it did that, it wouldn't run very well. While that cam opens quite a bit earlier for air flow, I wouldn't think it would effect the exhaust cycle..... exhaust opens at the same time on both..... There might be a small amount more air in the cylinder due to a longer opening time, but I don't think without boost it would be effectual on the exhaust braking effect... . Hmmmmm... . Robert, go work on your truck so we can all know firsthand!!!!

That was my thought as well. None of the cam mfgr's I talked to had even thought about how a cam would effect exhaust braking, and actually they all thought the backpressure would rise with a cam, but thats not the case. With the stock cam I made 40 psi of backpressure at about 1400 rpms, now it takes almost 1600. By about 2400-2500 the pressures match stock vs my cam.



All I know is I read about several people claiming lower exhaust brake retarting power after a cam swap, and the fact that now my retarding pressure is lower per rpm and my IAT's now rises 6-10*. I didn't beleive it would happen either... but I have seen the hard numbers.



The exhaust does NOT open at the same time, at least not on a 3rd gen. That's one of the main reasons to run a cam in a 3rd gen. . The issue with exhaust brake power could be directly related to 3rd gen's and my not be noticed on 1st and 2nd gen trucks. Also I know that on 2nd gen trucks guys have to periodically clean their MAP sensor from minor reverse flow from the EB, where this is not an issue on a 3rd gen with a stock cam. . I'll know in a few months if its an issue on a modifed cam. I plan to pull my MAP sensor when I am installing my new turbo.

 

[HHhuntitall]

Hmmm, now I'm curious. Looking at the cam numbers Robert posted above, I thought he was comparing a stock cam... . That was a MARINE cam. So the stock cam in our 12v Dodges is at 204*, and the HPCR is at 191*, so now I can see where there could be a reduction in the exhaust braking effect, as some piston speed is lost in compression before the valve opens. I'd think the engine braking effect would be a little higher than stock, though. Of the engine itself, that is. Seeing as how you have the cam installed and the numbers in front of you, I'll have to say,"You know better than I would!!" Certainly didn't want to step on any toes there. But that's what happens when an uneducated man opens his mouth to talk about something he "don't know crap 'bout"!! I do like the look of the Colt Cam Stage 4..... no fly cutting, just drop in..... and hammer down!!

 

[AH64ID]

It's still kinda fuzzy for me as to why it happens. To be honest I was looking at the 175/210 cam but didn't becuse I was affraid of overpowering the exhaust brake, until I read about the reduced effect and then the numbers I saw... My break still works amazing, I don't feel any reduction in effect, I just see lower backpressure.



I am guessing you saw all the specs on the colt site, but for folks who haven't.



Cummins 5. 9L Custom Cam Shafts - Improve your Diesel Performance with Colt Cams

 

[RustyJC]

If there's more overlap and/or more intake duration, the intake valve will begin opening earlier (more degrees before TDC). This will allow the cylinder pressure to take the path of least resistance into the intake at trailing throttle instead of being forced against the closed exhaust brake butterfly valve, thus dropping retarding horsepower generated by the exhaust brake and allowing some fouling of the MAP sensor.



Rusty

 

[DVolk]

just curious what are you running for fuel lines ? and what did you do to marry the wiring harnesses to gether ?

 

[RSchwarzli]

Fuel lines are 3/8 rubber lines as it is a FASS pumped truck.



As for wiring, I made all my own harnesses. I merged a 98 motor harness with a 93, then wired my Autometer gauges into the new harness as well. Not much stock in wiring minues the main ones behind the dash.

 

[DVolk]

Im not real shure on the fuel lines , ive thought about metal fuel lines but then

I think about my big rig stuff and there all steel braded lines from the tanks . As i see in Summit and jegs you can buy deisel approved lines for around $30 for 3/8" and 1/4" lines etc for 25 foot roles . I guess really there isnt much to add onto the 93 wireing harness to activate the fuel sylinoid etc maybe a after market tach ? What is the reason for the Fass Pump as they clain that piston pump is good for 400 HP ????

 

[RSchwarzli]

FASS - The motor is running twins and 60 psi of boost/600 HP. Thats why.



As for wiring, yes, and no. Simple things like AC compressor, fuel pre heaters, etc all need to be changed. Also I am running 20 some odd gauges. Thats alot of wire.

 

[HHhuntitall]

FASS - The motor is running twins and 60 psi of boost/600 HP. Thats why.



As for wiring, yes, and no. Simple things like AC compressor, fuel pre heaters, etc all need to be changed. Also I am running 20 some odd gauges. Thats alot of wire.

SUPPOSED TO BE 600hp..... I bet it won't do 500!!! Let's see you prove me wrong... ... . this week!!!



AWWW, C'mon, it wouldn't take you 3-4 days to put it together... ... ... ... ... working 24hr shifts with a crew... .



Just a friendly prod... mine's not running either... . :-laf

 

[RSchwarzli]

SUPPOSED TO BE 600hp..... I bet it won't do 500!!! Let's see you prove me wrong... ... . this week!!!



AWWW, C'mon, it wouldn't take you 3-4 days to put it together... ... ... ... ... working 24hr shifts with a crew... .



Just a friendly prod... mine's not running either... . :-laf

Smart butt. :-laf







I really dont know what the actual power will be. Everyone I ask says they have no clue but it will be better than the 350 I was planning on!



If it could be done in 24 hrs, I would bring every friend I have in and get er done! I am so ready to be driving vs wrenching!

 

[RSchwarzli]

Well, everyone remember this shot?



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Well, this is what it looks like today!



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Decided to fire ring the head:



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And whileit was off it was decked:



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And as I want to do things right, may as well post it for better breathing! No more cutting corners!



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And the new gasket ready to roll:



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[ENafziger]

So, is the head ready to put back on? I'm so excited about you getting the truck back together, that I wish I lived closer to help you work on it!!!

Keep the updates coming!

--Eric

 

[gtoli]

So, is the head ready to put back on? I'm so excited about you getting the truck back together, that I wish I lived closer to help you work on it!!!

ROAD TRIP!!!! Oo.

 

[RSchwarzli]

So, is the head ready to put back on? I'm so excited about you getting the truck back together, that I wish I lived closer to help you work on it!!!



Keep the updates coming!



--Eric

Head is ready to go on as soon as I swap the cam. Easier to do that first.



My issue with the cam is I found out on the first gens you need to either cut the center support of the rad core, or remove the rad core period. The cam gear hits the center brace!#@$%!



The job just got bigger! Seems normal for this project!:-laf



I appreciate the offer for help! If I get to the point I call on the entire TDR to come finish it I will let you know!:-laf

 

[BIGNASTY]

Nice truck but can I move into your shop! At my new address in MT I have built a Steel span type shop but im afraid its going to be a 60ft refrigerator in the winter.

 

[RSchwarzli]

As long as you are handy with wrenches..... :-laf