just want some reassurance on combo choices

I remember talking to Ron Iskenderien on the phone.
I was talking about getting the Cam made for my Trans Am.
He said no problem I can grind it again.
Led to engine theory.
I praised how Good His Camshaft worked the last one.
And the Tremendous hit punch of torque and Power that would not lay down.
He laughed.
I brought up those Online Dynamic Compression ratio calculators.
He immediately stated they were Crap Shit all.
Caught me off guard.
180 of what Grumpy taught us all.

Ron Iskenderien was and is still Right Correct.
 
Grumpy never stated the online dynamic compression calculators were always going to be giving exact results,
only that they tended to be a good useful guide to keep you from making really bad mistakes.
experience helps a great deal, and while the soft ware dynos do tend to predict rather well,
BUT only if provided with all the input data is correct, even they are simply a tool or guide.
for example I think all the soft ware dyno results predicted so far on this 400 are about 30 ft lbs and 35 hp low.
WHY?
LiftIntake CFMExh CFM% Exh/Int
0.200 145 11076%
0.300 207 145 70%
0.400 258 180 70%
0.500 283 206 73%
0.600 285 213 75%
0.700 291 216 74%
0.800 297 218 73%
software dynos are a good tool but they are never exact, they show trends and approximate results

well many of the previous similar engines I built that got dyno tested produced a bit higher than the predicted numbers
then these calculators
http://www.wallaceracing.com/calcafhp.php
http://www.bgsoflex.com/cgi-bin/flowcalc.cgi?cfm=296&tp=28&mode=Inches_Water&cid=400&cyl=8
https://www.hotrod.com/articles/airflow-research-cylinder-power/
https://www.powerperformancenews.com/tech/cylinder-head-tech-airflow-vs-power/

sgndl.png

now that problem may be in the parts selected or the data input but its not a good indicator ,it tends to show that some data in the software, or component is mis-matched
Id also point out that about 6400 rpm is about the max most hydraulic roller cams in a sbc will maintain valve train stability unless a reve kit and stud girdle are employed

Duration_v_RPM-Range_wIntakeManifold01.jpg
 
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Grumpy said:
Grumpy never stated the online dynamic compression calculators were always going to be giving exact results,
only that they tended to be a good useful guide to keep you from making really bad mistakes.
experience helps a great deal, and while the soft ware dynos do tend to predict rather well,
and only if provided with all the input data is correct, even they are simply a tool or guide.
for example I think all the soft ware dyno results predicted so far on this 400 are about 30 ft lbs and 35 hp low.
WHY?
LiftIntake CFMExh CFM% Exh/Int
0.200 145 11076%
0.300 207 145 70%
0.400 258 180 70%
0.500 283 206 73%
0.600 285 213 75%
0.700 291 216 74%
0.800 297 218 73%
software dynos are a good tool but they are never exact, they show trends and approximate results

well many of the previous similar engines I built that got dyno tested produced a bit higher than the predicted numbers
then these calculators
http://www.wallaceracing.com/calcafhp.php
http://www.bgsoflex.com/cgi-bin/flowcalc.cgi?cfm=296&tp=28&mode=Inches_Water&cid=400&cyl=8
https://www.hotrod.com/articles/airflow-research-cylinder-power/
https://www.powerperformancenews.com/tech/cylinder-head-tech-airflow-vs-power/

sgndl.png

now that problem may be in the parts selected or the data input but its not a good indicator ,it tends to show that some data in the software, or component is mis-matched
Id also point out that about 6400 rpm is about the max most hydraulic roller cams in a sbc will maintain valve train stability unless a reve kit and stud girdle are employed

Duration_v_RPM-Range_wIntakeManifold01.jpg
Click to expand...

Roller Camshafts hate hitting valve float.
Failure is imminent.

Enough Airflow to hit 600 HP in theory .
Super Stock High Rev but short engine life 700 Hp.
 
Im not debating the software dyno result, based on the input data was correct, it looks reasonably close.
I'm simply stating that several very similar engines built in the past, provided maybe 5%-10% more power.
keep in mind the software can,t differentiate between an off the shelf intake or one extensively port matched and ported,
, it can,t tell the difference between a crap valve job and a 5 angle valve job with a back cut valve,if port and bowl clean-up was done,
or headers blended entrances with matched length 38" primaries and 18"long 3.5" collectors and ones with
20 inch tube primaries and a 4"long 3" collector, and it certainly can,t account for a good tune vs one not so well balanced ETC.

http://garage.grumpysperformance.com/index.php?threads/engine-dyno-predictive-software.895/

http://garage.grumpysperformance.com/index.php?threads/building-custom-headers.961/

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/
 
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Grumpy said:
Im not debating the software dyno result, based on the input data was correct, it looks reasonably close.
I'm simply stating that several very similar engines built in the past, provided maybe 5%-10% more power.
keep in mind the software can,t differentiate between an off the shelf intake or one extensively port matched and ported,
, it can,t tell the difference between a crap valve job and a 5 angle valve job with a back cut valve,if port and bowl clean-up was done,
or headers blended entrances with matched length 38" primaries and 18"long 3.5" collectors and ones with
20 inch tube primaries and a 4"long 3" collector, and it certainly can,t account for a good tune vs one not so well balanced ETC.

http://garage.grumpysperformance.com/index.php?threads/engine-dyno-predictive-software.895/

http://garage.grumpysperformance.com/index.php?threads/building-custom-headers.961/

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/
Click to expand...
They are both really good cams the Crane & Isky.
John's Program does a better job taking VE Cylinder rate into calculations than your software, Rick's & Mine.
Why Results are much different than expected.
I noted the Isky Cam does not need a big CFM carb to perform.
The Crane Needs a large cfm carb to optimize.
Smaller carb will provide better throttle response .
Big CFM carb needs the Bells & whistles & top secret tricks done by BLP Bolaws, AED, ect. Stuff very difficult or impossible to pull off at home.

Isky has better torque nice clean curve.

Is what it is.
 
Last edited by a moderator:
Grumpy said:
Im not debating the software dyno result, based on the input data was correct, it looks reasonably close.
I'm simply stating that several very similar engines built in the past, provided maybe 5%-10% more power.
keep in mind the software can,t differentiate between an off the shelf intake or one extensively port matched and ported,
, it can,t tell the difference between a crap valve job and a 5 angle valve job with a back cut valve,if port and bowl clean-up was done,
or headers blended entrances with matched length 38" primaries and 18"long 3.5" collectors and ones with
20 inch tube primaries and a 4"long 3" collector, and it certainly can,t account for a good tune vs one not so well balanced ETC.

http://garage.grumpysperformance.com/index.php?threads/engine-dyno-predictive-software.895/

http://garage.grumpysperformance.com/index.php?threads/building-custom-headers.961/

http://garage.grumpysperformance.com/index.php?threads/calculating-required-exhaust-pipe-size.11552/

http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/
Click to expand...
I think you mean 30 inch long primary tubes.

Problem with many Musclecars & especially Corvettes is ground clearances.
Off the shelf headers today not really that good as you know.
Custom built needed.

Chevy Big Block has best off the shelf headers for A & F boy Chevelle & Camaro.
Still Hooker & Headman are #1.

Pontiac RAIV & SD455 its early Trans Am 2nd gen.
Hooker #4202.
2.000" primary.
28.0 inch long.
3-1/2 Inch collector.
Work real nice.

SBC to get 4.00 inch collector you have to fab TIG on specialty pieces.
Then everyone wants 2-1/2" yet.
Look what happens on DC...Pro Tour lingers a bit yet.
Selling Race Tech we know impossible.
 
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I'm still curious about the other isky grind, the hr-558 and the clay Smith cam. I think the Sim is a little low. But it shoesan excellent trend and response curves.
 
Isky custom ground 1.6 dp.PNG
Here is the Custom Isky on the Dual Plane

three cam overlay.PNG
All three dual planes on Overlay both Isky and Grumpy's crane I personally out the three like Brian's choice just my .02 .
 
The way I see it Grumpy No Exotic parts are Required going Isky.
Making Fantastic Power for the Street.
Be 100% Reliable.
Able to use pump gasoline with No Octane Booster.
Be easy to Tune.
We are in the Safe Zone you prefer.
Unless Racing Hellcats but we are not with this 400 sbc.
Going to stomp many with a Real Nice small block.
It will sound fantastic passing people.

Only a Big Block Chevy or Pontiac 455 can do Better.
 
Looked at comp lobe catalog all are similar .050 and advertised gotta say Isky here. Pretty close all specs reality comes to who you want cam from I like the Isky but that's me Brian loves Isky also what we have ran and used in past. Just as grumpy Rick used crower and crane. Has Crane added any grinds lately I have not been on there site in long time.
 
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