383 building advice

Thank you Rick for good and valuable input.

I am wondering about the Hydraulic Intensity of 48, is this a high no.? As the Crower 00471 has 50, I wonder if these 2 deg. make a large difference ?.
What I can see is that the Jones cam come out at 8 i DCR and with my limited knowledge it seems that it could be a interesting choice. Would be very interested to hear if Grumpy have some comment to this cam, and if it could be a good alternative for my engine.

From what I can see the figures for advertised duration for the crane cam is at @.04", and if I have understood it correctly these figures can not be used directly into the table for dynamic compression, or am I wrong on this ? I think I read that you need to subtract some degrees to get the figure for @.06 and use this figure.
I read somewhere that a good estimate of the duration @ .006" will be 275° in and 283° ex. for this cam, but I have sent a email to Crane to check.

I also got a reply from Howard cams today and they proposed a 111145-10, which I have attached spec for.

I will check some more and hopefully learn some more on my way.

Regards

Pal
 

Attachments

  • 111145-10.xls
    18.5 KB · Views: 8
cornor said:
(1.) Thank you Rick for good and valuable input.

(2.) I am wondering about the Hydraulic Intensity of 48, is this a high no.? As the Crower 00471 has 50, I wonder if these 2 deg. make a large difference ?.

What I can see is that the Jones cam come out at 8 i DCR and with my limited knowledge it seems that it could be a interesting choice. Would be very interested to hear if Grumpy have some comment to this cam, and if it could be a good alternative for my engine.

(3.) From what I can see the figures for advertised duration for the crane cam is at @.04", and if I have understood it correctly these figures can not be used directly into the table for dynamic compression, or am I wrong on this ? I think I read that you need to subtract some degrees to get the figure for @.06 and use this figure.
I read somewhere that a good estimate of the duration @ .006" will be 275° in and 283° ex. for this cam, but I have sent a email to Crane to check.

(4.) I also got a reply from Howard cams today and they proposed a 111145-10, which I have attached spec for.

I will check some more and hopefully learn some more on my way.

Regards

Pal

1.) You are most welcome, it's enjoyable just helping!

2.) I think I asked Grumpy to comment on this last time, since I don't have tons of
experience with these numbers. I can calculate them, but then I'm lost when it
comes to helping someone else. I don't want to speak about something that I don't
direct experience with.

3.) If they give you a closing number at advertized duration, then use that, it's
the best you are going to get. It's usually quoted at .004 or .006 inches of lift. Your
number @.04" is actually .040 or forty thousands lift. Maybe you just left out a zero.
The only estimate I've seen is by Grumpy ...... add 15° to the duration @.050 inches.

You lost me when you stated @.06, I've not seen that number used for anything
camshaft related. I've not seen an estimate based on .006 and add 8°, this is usually
used as a closing number and can be used for DCR directly.

4.) It will be tomorrow before I can take a look at the Howard cam ..... this is so
much fun. I only hope you are enjoying the conversation.

 
guys , keep in mind this is NOT an exact BLACK and WHITE OFF or ON point your looking to hit, as you select components in a build, that allows you to achieve the ideal combo, its more like a SERIES of DOZENS of OVER LAPPING BELL CURVES ,EACH CHOICE IS A COMPROMISE in some area,yes you can make intelligent well informed choices to maximize your results but don,t think small mistakes or perfect choices will totally ruin or make a combo far better than anyone elses, its the combination, generally not a single choice (UNLESS ITS SPECTACULARLY BAD) that makes or breaks the final results theres dozens of choices to be made and each has a sweet point that will vary depending on the choices made with the other components selected, EACH CHOICE WILL EFFECT THE RESULTS YOU GET WITH THE OTHER CHOICES ,YES, YOU CAN MAXIMIZE YOUR RESULTS BY TRYING TO GET AS CLOSE TO THE PEAK ON EACH CURVE AS YOU CAN BUT SOME CHOICES WILL NECESSARILY NEGATE THE BEST SELECTION ON OTHER CHOICES.
ID also point out that MOST ENGINE DYNO PREDICTIVE SOFT WARE IS NOTORIOUS FOR PRODUCING LESS THAN REALISTIC RESULTS < AND WHILE ITS USEFUL ITS HARDLY RELIABLE, AS TO PREDICTING ABSOLUTE POWER/TORQUE NUMBERS AT ANY RPM RANGE

bellcurve.GIF

COMPRESSION TO REQUIRED FUEL OCTANE
bellcurve.GIF

FUEL OCTANE REQUIRED FOR CYLINDER HEAT LEVELS
bellcurve.GIF

EXHAUST SCAVENGING EFFICIENCY
bellcurve.GIF

THERMAL LOSSES TO FRICTION AS RPM AND LOADS INCREASE
bellcurve.GIF

OIL TEMPS TO LUBRICATION EFFICIENCY
bellcurve.GIF

IGNITION ADVANCE CURVE
bellcurve.GIF

COOLANT TEMPS VS COOLING EFFICIENCY
bellcurve.GIF

AIR TEMP VS COMBUSTION EFFICIENCY
bellcurve.GIF

QUENCH EFFICIENCY
bellcurve.GIF

PORT FLOW VELOCITY
bellcurve.GIF

PORT STALL SPEED
bellcurve.GIF

VALVE CROSS SECTIONAL AREA TO CYLINDER VOLUME
ETC...ETC...ETC.
compccsguide.png

lets say the piston deck height averages .011 below the block deck, then you would subtract .011 from .044 and get .033, you would find a .030-.033 head gasket (.032 is very common)


lets say the piston deck height averages .011 above the block deck, then you would add .011 too .044 and get .055, you would find a .050-.052 head gasket


p173610.jpg

they measure the piston deck height after the machined block has the rotating assembly test fitted
deckx.jpg

piston%20down%20in%20hole%20at%20TDC.jpg


then buy the required head gasket thickness to allow the quench to fall in that .040-.044 range

if you select a certain STATIC COMPRESSION, your limited to the fuel octane ratings you can use without getting into detonation
this also changes with the cylinder head temperature, quench, cam timing, overlap, cylinder scavenging, ignition advance, the finish or thermal barrier coatings on the piston and combustion chamber, oil temperature, coolant temperature fuel and air temperature, use of and combustion temp regulators like methanol/water mist injection, and a dozen other factors each one of which is going to effectively generate a bell curve of performance that over lays and effects the other factors its melded with.
you can look up info related to each listed factor above "and a dozen more" and try to select the best possible choice, but what you'll eventually realize is that its 100% impossible to maximize ALL the potential, related factors simultaneously.
In an ideal internal combustion 4 stroke engine there would be zero friction, the fuel would ignite instantly at TDC, produce ever increasing pressure from TDC to at least 145 degrees past TDC on the power stroke,at a rate just a bit below a realistic safety factor concerning the strength of the rotating assembly and burn completely leaving no residual emissions or ash and achieve near 100% efficiency with little heat,loss.
we currently use about 8:1 DYNAMIC compression as a target simple due to the crappy low octane pump fuel available currently in most areas to prevent engine damage



viewtopic.php?f=55&t=2718&p=41142&hilit=octane+calculate#p41142

viewtopic.php?f=52&t=4081&p=10861#p10861

http://victorylibrary.com/mopar/cam-tech-c.htm

viewtopic.php?f=50&t=9816&p=40642&hilit=detonation+damage#p40642

viewtopic.php?f=52&t=727

http://www.race-cars.net/calculators/compression_calculator.html

http://garage.grumpysperformance.com/index.php?threads/a-few-calculator-links.7108/#post-27382

http://www.projectpontiac.com/ppsite15/compression-ratio-calculator

http://www.wallaceracing.com/dynamic-cr.php

http://www.rbracing-rsr.com/comprAdvHD.htm

http://performancetrends.com/Compression_Ratio_Calculator_V2.3.htm

http://www.wallaceracing.com/cr_test2.php

http://www.pcengines.com.au/calculators/Calculate dynamic Comp Ratio.htm

http://www.csgnetwork.com/compcalc.html

http://www.diamondracing.net/tools/

https://www.uempistons.com/index.php?main_page=calculators&type=comp

https://www.rbracing-rsr.com/compstaticcalc.html
 
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cornor said:
I also got a reply from Howard cams today and they proposed a 111145-10, which I have attached spec for.

I will check some more and hopefully learn some more on my way.

Regards

Pal

The Howard cams operates at a lower RPM compared to the Crower 00471.



 

Attachments

  • Compare_Crower00471_To_HowardCams111145-10.JPG
    Compare_Crower00471_To_HowardCams111145-10.JPG
    53.3 KB · Views: 34
viewtopic.php?f=71&t=555&p=45747&hilit=when+shift#p45747

this is one of those cases where you look at the predicted dyno result and instantly think, wow! look at that difference Id be foolish not to select one cam vs the other , but are you really basing the decision, on the facts?
a great deal about how a car performs relates to its power to weight ratio and its drive train gearing, obviously you'll want to gear the car and select tires etc. to maximize performance in the area ,or under the operational conditions that are most important too you!, this will generally require some compromises in other areas.
this is also where an over drive transmission allows you to get most of the performance benefits in both areas. a 3.73:1 rear gear ratio certainly will allow you to operate in the upper rpm ranges to extract the desired power

the fact is, your more than likely not basing the decision on the correct data, think it thru, you don,t really care about the low rpm torque as long as is available in sufficient quantity to easily move the average 3000 lb car rather effortlessly ,if its geared correctly, and it generally takes less than 250 ft lbs of torque and 80 hp to drive around town at part throttle
keep in mind you don,t use the whole power band while racing nor do you use the same section of the power band while driving around town as you do while racing.
while racing you'll seldom have the rpms fall much below the engines torque peak if the cars geared correctly to maximize its power transfer potential and it will shift at rpm levels above the power peak so it falls back near the torque peak.
your current 4 speed has a 2.2 first gear ratio, a 5 speed you referred to has a 2.87:1 first gear ratio and a .64:1 OD ratio.
ideally the rear gear x the transmission first gear ratio will fall in the 10:1-10.5:1 range, with the muncie and that 3.73:1 rear gear you have a 8.2:1 which if further hurt by the TALL 31" tire size
the TEMEC 2.87:1 first gear x that 3.73 rear gear come out to a 10.7:1 which is about ideal with that tall 31" tire

http://www.summitracing.com/parts/awr-t ... /overview/

http://www.datsuns.com/Tech/whentoshift.htm

http://www.welltall.com/ymc/discovery/car/shiftpt.html

viewtopic.php?f=71&t=555

while driving for decent fuel economy youll rarely exceed 4000rpm
Compare_Crower00471_To_HowardCams111145-10.JPG


notice the power curve used while racing would be rather different
11145-10.jpg
 
Thank you Grumpy and Rick for educating me :) . You have come up with so much interesting and useful information, and I really appreciate this. I understand that there is some many other factors to consider than only looking at the engines torque and power curve. My first impression looking at the Howard visa Crower curves was that the Howard would be a better cam for a street driven car, but then after considering the good inputs from Grumpy, this may not be so clear.

I will in the near future have to make some decision on what additional parts I shall purchase. If I buy a two peace timing cover, it will make it easier to change the cam in the car later, IF I end up with something that not work with my car and my driving style.

Thank you again and good night from Norway. Pal
 

Grumpy,

It may not make a big difference in the concept you are explaining. When you
labeled the graph, the "Torque Peak" label seems to be pointing to the Howard
torque curve and the "Shift Here" seems to be pointing to the Crower HP curve.

Is this what you intended???

 
I was not, really concerned with which cam particularly was being targeted, I was pointing out that on a 383, your generally limited with a hydraulic valve train and piston speed limitations to about 6400-6500 rpm as an upper rpm limit if long term durability is a reasonable concern, (and shifting at 6300rpm sure won,t hurt durability) and what I'm saying is you generally shift at or a bit over the engines power peak and keeping in firmly in mind the limitations imposed by piston speed and valve train limitations, and ideally shifting so your falling back at or near the torque peak, (usually and Id say, ideally ,just a bit lower in the rpm band), this will generally produce the most consistent and highest average useful power and torque applied to the driving wheels to propel the car.
that milder Howards cam potentially has a good deal more lower rpm torque, than the Crower cam its being compared to, (according to the software dyno prediction) below 4000rpm but thats almost an illusion in one respect, and heres why,if you installed both cams in the car separately and test drove them you would without doubt notice the milder cam produced a bit more low rpm response and was easier to drive accelerating at part throttle, but once you decide to accelerate briskly and open the throttle , what happens? your engine rpms rapidly increase as the engine takes advantage of the now available increase in air flow, remember you control the engine rpm by RESTRICTING OR STRANGLING THE AVAILABLE AIR FLOW AVAILABLE, so at part throttle that mild cam takes full advantage of what,limited air flow is available, but once you make a good deal more air flow available, it can no longer keep up, its not lifting the valves high and long enough to allow nearly the same air flow as the slightly more aggressive longer duration Crower cam, thus once the RPMS have increased , and your demand for increased power is there the Howards cam rapidly falls behind.Think about that a second!
when you don,t really need the power the milder cam provides the torque and as long as your not demanding more than part throttle it would suit the demands in most cases rather well, yet if you really want the car to accelerate, its going to fade noticeably , on the other hand the Crower cam provides all the power you can use in the lower rpm ranges AND more power in the UPPER rpm ranges, but it will have a bit less off idle responsiveness.
now everything is rather relative, and if you talk to RICK Im reasonably sure he can describe the way that cam responds to him pushing his foot down on the throttle,and I doubt he will tell you hes found it seriously lacking in responsiveness or power.
and so can I, having installed and run it previously in my 1985 TPI 383 powered corvette. every choice you make is a compromise, personally I selected a CRANE 119661 as ideal for my particular combo and I tried at least a dozen cams over 7-9 years .
keep in mind its not just the cam, factors like gear ratios stall speed car weight header design come into play my vettes got the same 3.73 rear gears but it has 25" tall tires and a 700r4 trans with a 3200 stall converter

keep in mind the formula for horse power
torque x rpm /5252=hp
higher rpms allow,and engine matched too proper gearing to have the engine perform more work in a given time frame


BTW
one of the cams I tried after listening to a friend give it rave reviews was the Erson 119824 WITH 1.6:1 ratio roller rockers and a TPI intake, having good off idle torque and good power all the way to the peak rpm where the stock auto transmission shifts at, I must admit but it lacked power above about 5000rpm, ESPECIALLY after I swapped to the ported holley stealth ram intake
ersonret.png

http://garage.grumpysperformance.co...etting-much-harder-too-read.11162/#post-50044
viewtopic.php?f=32&t=430
 
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