Dan From Sault Ste Marie Ontario

Well if you can read Taylor's book, then you just might have the math skills needed for "Design and Simulation of Four Stroke Engines"
 
I am not afraid of the math...it just takes me forever to figure it out. Took lots of it in school (some how I passed my PDE course, but it was only barely)
 
I used to easily breeze through most math like trig, and most geometry,
those disciplines, were logical at least you could visualize the answers that made some sense ,
but once I got into later algebra and calculus I was not having fun at all!
 
Alright Indy, here is the data

Spec Value
Bore & Stroke: 3.903" x 4.000"
Displacement: cubic inches 383ci
Rod Length: 6.125"
Heads Make/Model with flow numbers: Flow (CFM) at several lift points. stock 706 heads that I will port- for flow see note 1
Combustion Chamber Size in CC’s: 61cc
Dome Volume: For a domed piston use a (-) negative number: 0
Valve Relief Volume: For a piston with valve reliefs or dish, use a (+) positive number. +15cc
Deck Clearance: 0.005"
Head Gasket Bore: 3.910"
Head Gasket Thickness: 0.036"
Valve Sizes Intake/Exhaust: 1.89/1.55
Intake Manifold Model Type: [Single or Dual Plane] stock ls truck manifold (not sure what to put here)
Model #: 78mm TB
Carburetor Size or EFI (CFM): 792 cfm
Blower/Turbo Make/Model: none
Belt Ratio: no turbo
SCR & DCR: SCR: 10.3 & DCR 8.3 (DCR listed with CAM info in note 2, I calculated it with +25 degrees from 0.050" as per the wallace racing calculator info this is slightly higher than the DCR calculated based on seat-to-seat DCR)
Header Tube Diameter: 1-7/8"
Cam Card: Need all 8 valve timing events at seat-to-seat and at 0.050” & lobe lift or valve lift See note 2
Rocker Ratio - Intake/Exhaust: 1.7
Cam Installed per Cam Card, or Retarded or Advanced: 0 advance or retard
Fuel Used: Gasoline, Methanol, Ethanol, E85 ..... Gasoline

Note 1 - Cylinder Head flow *this is for non-ported heads*

Lift (inches) Intake (cfm) Exhaust (cfm)
0 - 0 0
0.05 27.7 24.6
0.1 59.9 48.7
0.2 126.5 89.1
0.3 180.6 126.2
0.4 213.4 158.1
0.5 220.5 180.9
0.6 231.3 193.5
0.65 234.2 198.1
0.7 237.1 201.6

Note 2 - Camshaft info *SCR is posted with each camshaft*
INTAKE EXHAUST
opens closes opens closes DUR @ 0.050" DUR @ 0.006" LIFT with 1.7 rocker
BTDC ABDC BBDC ATDC int/exh int/exh LSA int/exh DCR
Option 1 -1 39 47 0 218/227 278 287 112 0.600/0.600 8.3
Option 2 0.5 44.5 53.5 -1.5 224/232 280 287 115 0.590/0.590 8.3
Option 3 3 43 55 3 226/238 275 288 113 0.600/0.600 8.1

I will upload a pdf of the cam info in case that table I made doesn't make sense, or if your screen size makes it hard to read.
 

Attachments

  • Specs for calculator.pdf
    228.1 KB · Views: 1
  • Note 1 - Head flow.pdf
    212.5 KB · Views: 2
  • Note 2 - cam info.pdf
    221.5 KB · Views: 2
Wow, that's the best info I have received so from anyone! Usually I have to go looking thru the thread or DL the cam specs.
Thanks!

I might have something later this afternoon.
 
As I look thru your great info, I have questions about some of your numbers on Note 2.

Do you have VVT or variable valve timing ?
How are you changing the LSA or Lobe Separation Angle ?
Do you have a manufacture's name and part number ?
How much did you bore this block ?
 
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Do you have VVT or variable valve timing ?
No VVT
How are you changing the LSA or Lobe Separation Angle ?
I was not changing or calculating anything here, just posting what the manufacturer has listed. (I am not sure I understand your question, please clarify).
Do you have a manufacture's name and part number ?
Option 1 - Summit Racing 8720 - https://www.summitracing.com/parts/sum-8720
Option 2 - Crane Cams 1449121 - https://www.summitracing.com/parts/crn-1449121
Option 3 - Summit Racing 8707 - https://www.summitracing.com/parts/sum-8707
How much did you bore this block ?
The bore is 3.905 from 3.780 I was looking at the ATK blocks as it comes magna fluxed, bored and aligned honed - https://www.high-performance-engines.com/product-p/13g2.htm

Feel free to inform me on the quality of the summit cams. I live by the motto "don't buy cheap tools or condoms" from everything I have read on this site I can tell it applies to engine components too.
 
I was not changing or calculating anything here, just posting what the manufacturer has listed. (I am not sure I understand your question, please clarify).
Ok, I didn't realize you had 3 different camshafts in mind, hence my confusing about the 3 options.

The bore is 3.905 from 3.780 I was looking at the ATK blocks as it comes magna fluxed, bored and aligned honed - https://www.high-performance-engines.com/product-p/13g2.htm
If that is taking a 4.8L block and boring .125", that is usually considered to be way to much. Now I've
not been involved with the LS motors, so maybe there is something different for them. Or maybe you
are buying a block that started out larger from the factory, so you are not actually boring it .125".

The Option 1 camshaft must have asymmetrical lobes which my software does not know how to handle.
I have talked to the software developer Larry Atherton and he expressed a interest in making the
software so it could handle them. But nothing has happened yet.

I will look at the other two and see what I come up with.

As far the the quality of Summit cams, I will have to defer to Grumpy who has the experience to address
this concern.
 
Concerning the Crane 0049121 Camshaft.

My software calculates a 1° difference then what you have listed in your PDF file. Initially I entered the
"0.050 Inch Duration:" on the "Camshaft Specs" tab as 224°, but when I move to the "Valve Event Timing"
tab and enter your number for the "Intake Valves Closes (IVC)" as 44.5° it will change the 224° to 225°.
Note the area highlighted in GREEN on the graphics below.

This is what happens sometimes when there is an asymmetrical lobe, but it's usually more pronounced.

Where did you get your numbers? If you have the cam card please post so I can include it in my camshaft
library, those things can be hard to find sometimes.

Yes, these kinda of things are typical of getting to a valid HP/TQ graph.

HR_Crane1149121_Tab-CamshaftSpecs.jpg
HR_Crane1149121_Tab-ValveEventTiming.jpg
 
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Here is the cam card info as posted in the Crane Master Catalog (see upload)

If that is taking a 4.8L block and boring .125", that is usually considered to be way to much. Now I've
not been involved with the LS motors, so maybe there is something different for them. Or maybe you
are buying a block that started out larger from the factory, so you are not actually boring it .125"

The iron block can be bored out all the way to 3.910 from what I have read, but you have to check the block real good (that's why I was leaning to purchasing a block). There is a good table in the link below showing the max bores for various LS blocks.
https://www.hotrod.com/articles/max-overbore-for-ls-blocks/
 

Attachments

  • Crane 1449121 CAM Info.pdf
    462.5 KB · Views: 3
Sum 8707 CAM CARD
sum-8707_xl.jpg
 
Let's start with your first Summit camshaft 8720 and resolve my questions about it before we
move on and making this anymore confusing. One thing at a time or we will get lost in all the
changes/differences trying to discuss all three camshafts at the same time! Let me email Larry
Atherton and get his input. It's time I headed inside for tonight, so I will email him tomorrow.
When I get his input I will post again, hopefully tomorrow afternoon.
 
Sent an email to Larry Atherton, so I'm waiting for his response.

In the meantime, I wanted to confirm the changes I made to the file called "Note 2-Cam Info". Let me know what you think.

CamInfo-Note2_Corrected.jpg

I found the Crane cam specs. Did you notice that it changes the firing order ?

Crane_HR_1449121_590_590.jpg
 
Watched engine masters yesterday about that. First I heard of such. It made a very small change but no reason why and determined not really worth effort.
 
Thanks Rick!
I remember there was a link to find the crane cam cards, but I could not find it. What you shared is exactly what I remember finding. Do you have the link?
 
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