How to build a motor for top end power ?

[THEFERMANATOR]

Yeah, that's what he told me, better lubrication. And it was faster to do, quicker turn around time. I just wasn't sure if it was really the best/right option.

Knurling and then reaming is fine for a short duration use engine, but for an engine you plan on putting some miles on I would have guides put in. When you knurl the guides, you are also losing guide material to wear away so they will wear faster next go round. Most machine shops prefer not to knurl em as it is a band aid instead of a long term repair.

 

[THEFERMANATOR]

I wonder how late the intake closing point could be,and still be able to start ?

I'm sure you could push it out a good bit if you didn't mind starting on ether. I know alot of the guys pushing the envelope have went to cam profiles(and extremely lowered compression ratios) that require using ether to start the engine. Not great for a street driven engine, but works for a competition use engine. Or you could go to adjusteable rocker arms with rhoads lifters and have that wonderful lifter clatter to listen to at an idle(my least favorite option, but does work for some applications).

 

[6.2 turbo]

I just noticed today that my tach has a peg at 5000 rpms,but it kept revving higher,would guess around 5300 rpms. I would go solid lifters,before variable duration hydraulic. Or hydraulic with .002 lash.

 

[6.2 turbo]

From 4000 rpms and up is the problem area. Some of it might be fuel and timing,but I think there is something else going on. The exhaust output at those rpms is tremendous. I had a 1-1/8 inch waste gate open at 10 psi,but by 4000 rpms still made 27 psi boost. Seems like the stock cam is designed to only flow exhaust. If the exhaust valve would open later,would that help keep the exhaust flow down ?

 

[Mike K3500]

WOW 6.2 sounds kinda crazy... Now, are you running all this still with a side hung turbo set up or did you go center mount ??

Would really like to see this thing on the dyno and see how quick it is.

 

[6.2 turbo]

I don't think it runs that great ,just trying to figure out what I'm doing wrong. Still has the factory manifolds,and crossover pipe,with an external waste gate in the middle.

 

[THEFERMANATOR]

From 4000 rpms and up is the problem area. Some of it might be fuel and timing,but I think there is something else going on. The exhaust output at those rpms is tremendous. I had a 1-1/8 inch waste gate open at 10 psi,but by 4000 rpms still made 27 psi boost. Seems like the stock cam is designed to only flow exhaust. If the exhaust valve would open later,would that help keep the exhaust flow down ?

Sounds to me that you are going above and beyond what a stock engine was ever meant to do. You need to do a ground up look at it and start over if your going to dive into uncharted territory. Personally I owuldn't be trying to decrease exhaust output, but instead increase it to make it flow it better and then match the turbo and waste gate to what you are doing. Remember an internal combustion is nothing more than an air pump, the more efficiently one can get the air in AND out the better. I know on teh DURAMAX to cross over about 3300 RPM's efficiently, you need to do some head porting, and if you want to cross over 4,000 you need to do alot of head porting. Otherwise you are choking off the intake and not getting teh air into the cylinder despite having alot of boost on tap.

 

[3500GMC]

Well before it chucks a rod, do a video, I gotta hear this. :thumbsup:

 

[6.2 turbo]

Found this on SS diesel site, not real sure of the manufacturer though and kinda pricey at 599.00

Performance Roller Camshaft kit for all 6.5's in all trucks, all years, all VIN's.Includes a custom ground performance roller cam, new hydraulic roller lifters, and a free tube of cam assembly lube.Add power to your 6.5TD with our performance cam kit.
Specs as follows...

Advertised Duration (Exhaust):300 Deg
Advertised Duration (Intake):260 Deg
Cam Lift (Exhaust):.281"
Cam Lift (Intake):.281"
Cam Timing at .050" Lobe Lift (Exhaust Close):17 Deg BTC
Cam Timing at .050" Lobe Lift (Exhaust Open):39 Deg BBC
Cam Timing at .050" Lobe Lift (Intake Close):11 Deg ABC
Cam Timing at .050" Lobe Lift (Intake Open):13 Deg ATC
Degrees Overlap:65 Deg
Duration at .050" Lobe Lift (Exhaust):202 Deg
Duration at .050" Lobe Lift (Intake):178 Deg
Lobe Centerline (Exhaust):120 Deg
Lobe Centerline (Intake):101 Deg
Valve Lash (Exhaust):Hyd.
Valve Lash (Intake):Hyd.
Valve Lift (Exhaust):.422"
Valve Lift (Intake):.422"

Not real sure how this cam would behave with 300* ex duration.

SS Diesel is selling a stock cam. I put a degree wheel and dial indicator on my GEP motor,all my specs are within .001 of these. I also came up with a 109 lsa,which is also the same.

 

[ak diesel driver]

maybe GEPs have a diff cam than the oems?

 

[6.2 turbo]

Supposedly they are all the same,guess I should check a 6.2,and 6.5 GM cam also.

 

[6.2 turbo]

Another discovery,the stock cam is 7 degrees advanced,SS Diesel's appears to have 9 degrees advance.

 

[Mike K3500]

WOW ... 6.2 ..... VERY, VERY interesting,... NOW, to get the confirmed degreeeez of the DSG gear drive timing set... Bill hates them and claims 4* advance is ground / built into them ( also claims WILL not work with his "600.00" cams ), John "K" has NO love for Bill and claims there is only 2* built into the DSG gear drives ( AND claims Bill's cams are BS ). IF I had the time.. I would buy one of Bills cams and measure / degree the god damned thing and KNOW what is or what isn't = NO secrecy

I wish I knew of all this shat before I finished assembling my engine and put it in my truck.. I would have degree'd the damn thing my self.....

 

[buddy]

CIL6 had degree'd a stock cam a few years ago, and his results are below. Some of the values are a little off I'm sure, since the valve lift is very low on the exhaust. I'm sure that getting these numbers perfect is pretty hard, but how close is a degree wheel typically? Having the same person degree a GEP vs stock GM would be best for consistency in method and tools. I have long suspected GEP could be using the cams that the army spent money to have designed and tested to show a good improvement in their NA engines. My opinion on cams has already been posted at length in a couple threads, that there are gains to be had. Even though we are forcing air in, the question is if we are getting 100% efficiency when boosting. Does the valve open enough so that when you have 15psi of boost the cylinder is filled to the same? If the valve is a restriction then it might not. The valve does not even open enough to provide a cylindrical area between its outer circumference and the head, to equal to the cross sectional area of the head's port. So I surmise that some added lift would help in pre-boost off the line as well as in high RPM to fill the cylinder more efficiently. As well as a little more duration before the intake closes. I also agree that you want exhaust flow, anything to improve it is good, and then a larger turbine housing could be used. Closing the exhaust valve later is a good idea, as close to TDC as you have clearance for. There is only one reason Heath's cams would not work with a set of higher ratio rockers or the gear set, and thats because he brought the valves closer to piston interference, just as I would. But for the most benefit, you would need to make more clearance.

Intake center line = 101 deg.
Intake duration = 184 deg.
Intake valve lift = .404"
Intake valve drop @ TDC = .056"

open close
Intake = 12 deg. ATDC 16 deg. ABDC
Exhaust = 42 deg. BBDC 10 deg. BTDC

Exhaust center line = 117.5 deg.
Exhaust duration = 212 deg.
Exhaust valve lift = .355"
Exhaust valve drop @ TDC = .057"

Lobe separation = 109.25 deg.
Ground in advance = 8.25 deg.

 

[6.2 turbo]

I measured directly at the lifter, duration and opening and closure were all taken at .050. The actual opening and closing is much closer to tdc ,because the ramps are slow.

 

[EWC]

Years ago when I was looking for a cam , NAPA listed all the specs on their cams . That SS cam looks a lot like the stock cam . All the cams for the 6.2 and 6.5 were the same , no difference in years or if it was turboed .

 

[Mike K3500]

Looks to be 2 very different cams between the GM and GEP... Kinda funny to see that Walt is basically selling a GEP cam for $ 600.00 and calling it a "custom ground performance roller cam"
Now to have 6.2 degree the stock GM cam to see if his findings confirm the ones Buddy posted.

 

[EWC]

Buddy , you should delete those specs , not even close and no starting lift number ? The cam SS cam listed above is the stock cam .

 

[buddy]

Those specs were measured on a degree wheel by CIL6. And I do not believe that SSDS is selling stock cams. When another set of specs measured on a degree wheel of a stock cam are posted we can compare them.

 

[THEFERMANATOR]

What rocker arm ratio does the 6.5 use? Are these specs at the cam or at the valve? Just want to make sure everybody is using the same measurements as some people measure at the lifter, and others will measure at the valve. Would also be nice to have somebody check a new GEP otpimizer turbo engine, and then a N/A engine as many are buying up used N/A GEP engines and putting there turbos on them. Knowing teh milatry they very well could be using 2 different cams since they have different pistons and compression ratios between the 2.