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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082418
09/25/11 09:14 PM
09/25/11 09:14 PM
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Joined: Feb 2009
Posts: 1,532
off the grid
340B5
pro stock
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pro stock
Joined: Feb 2009
Posts: 1,532
off the grid
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Man you ask tough questions....makes my head hurt. But I'll be looking forward to the answers.
Yeah, it's got a smallblock.
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Re: Cam duration vs cubic inches
[Re: 340B5]
#1082420
09/25/11 09:51 PM
09/25/11 09:51 PM
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Joined: Jan 2007
Posts: 3,695
nc
emarine01
OP
master
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OP
master
Joined: Jan 2007
Posts: 3,695
nc
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Quote:
Man you ask tough questions....makes my head hurt. But I'll be looking forward to the answers.
This is what happens when I get bored  So if the 265 solid roller has a power band of say 5000 to 7500 in 340 cid... whats the power band @ 408? & to take it one step further if the cam is 108 in @ 104 in the 340... would it make sense to install it straight up in the 408?
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082421
09/25/11 10:01 PM
09/25/11 10:01 PM
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Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
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I don't have any answers for you but I'm hoping it isn't much.
I'm basically going from a 363 to a 408 with the same heads but a bigger valve, 20 cfm more flow, a solid roller from a flat tappet but the duration at .050 numbers are within 1 degree of each other but about .030 more lift. Since I can only buy 1 ratio of pro gear for my 8.75 it's much harder for me to change the RPM range I can run the car in. However since most racing down here these days is 1/8 mile it's a lot more forgiving.
"Follow me the wise man said, but he walked behind"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082423
09/25/11 10:38 PM
09/25/11 10:38 PM
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Joined: Feb 2009
Posts: 1,532
off the grid
340B5
pro stock
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pro stock
Joined: Feb 2009
Posts: 1,532
off the grid
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Ok you got me thinking about it
360/1728 X (RPM/2) = CFM
CFM /(408/1728) = (RPM/2)
The CFM answer from the 1st formula for the 360 is used in the 2nd formula to get the the RPM at which the 408 draws the same air.
Yeah, it's got a smallblock.
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082424
09/25/11 10:45 PM
09/25/11 10:45 PM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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The same cam and head with only a cubic inch change will make aprox the same hp. The larger engine will just make it at a lower rpm. For the 408 to to make its power peak at the same rpm as a 360 the camshaft will have to have more duration and heads need a larger port that moves more air.
Getting old just means you were smarter than some and luckier than others.
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Re: Cam duration vs cubic inches
[Re: dannysbee]
#1082425
09/25/11 11:20 PM
09/25/11 11:20 PM
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Joined: Aug 2006
Posts: 2,141
junction city oregon
viperblue72
top fuel
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top fuel
Joined: Aug 2006
Posts: 2,141
junction city oregon
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1 degree more duration per 10 cubic inches will keep you in the same power band everything else considered. This is just a general rule and hopefully this is correct cuz that's what I remember. So if you add 60 cubes add 6 degrees@050 would be best.
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082427
09/26/11 12:07 AM
09/26/11 12:07 AM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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Aprox 6700 for the 408 with the same heads and cam as the 360 with a 7500 power peak.
Getting old just means you were smarter than some and luckier than others.
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082428
09/26/11 12:21 AM
09/26/11 12:21 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Man you ask tough questions....makes my head hurt. But I'll be looking forward to the answers.
This is what happens when I get bored So if the 265 solid roller has a power band of say 5000 to 7500 in 340 cid... whats the power band @ 408? & to take it one step further if the cam is 108 in @ 104 in the 340... would it make sense to install it straight up in the 408?
Well I cant answer the question YET but I'm running
a 260/262 roller in my 416... I am hoping that it
peaks at 6800 rpm... this is on my W-5 416 I built
for the Rampage... I only want a 7000 rpm engine, max...
this is a throw together parts engine(everything I
had laying around the shop)... I want 550 or so HP
so I should be close
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082429
09/26/11 12:24 AM
09/26/11 12:24 AM
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Joined: Aug 2003
Posts: 43,200
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,200
Bend,OR USA
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I don't know the math but I did switch heads, intake and carbs. this year on my pump gas 518 C.I. street motor keeping the same solid roller camshaft similar to yours, 260 @ .050 intake and 266 @ .060 exhaust side. The motor had a set of CNC ported Eddy RPM heads (intakes flowed 310 CFM at .700 lift at 28 inches of water on a Superflow 600 bench)with a six pak intake and carbs, it made peak power at 5800 RPM the last time it was on a engine dyno and peak torque at 4600 RPM. I switch the heads to a set of Indy SR max wedge ports that flowed 350 CFM at .700 lift on the same flow bench as the Eddy RPM, the peak HP is now at 7000 RPM and peak torque was at 4800 RPM  The car use to cross the finish line in the 1/4 mile at 6200 RPM with the old heads and intake system and now crosses at 7000 RPM with the Indy 400-3 intake and a single Holley 1050 CFM Dominator, no other changes  I say use the cam you got to start with and see if you like the results 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082431
09/26/11 12:39 AM
09/26/11 12:39 AM
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Joined: Aug 2003
Posts: 43,200
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,200
Bend,OR USA
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Quote:
Wow, that's 300 more rpm drop than my best guess  So If we apply the 1* per 10 cube rule 360 to 408 lets say 5* more duration, about how much will rpm rise?
I'm a racer and engine assembler, not a engine sceinintest(SP  ) or theoryist   I can call Comp Cams race dept. tomorrow and get their engineers involved, if you want, That is who I use on new engine combinations for racing, PM me with more info on your total combination 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Cam duration vs cubic inches
[Re: Cab_Burge]
#1082432
09/26/11 12:49 AM
09/26/11 12:49 AM
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Joined: Oct 2004
Posts: 5,618
long island NY
Ari440
master
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master
Joined: Oct 2004
Posts: 5,618
long island NY
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Quote:
I don't know the math but I did switch heads, intake and carbs. this year on my pump gas 518 C.I. street motor keeping the same solid roller camshaft similar to yours, 260 @ .050 intake and 266 @ .060 exhaust side. The motor had a set of CNC ported Eddy RPM heads (intakes flowed 310 CFM at .700 lift at 28 inches of water on a Superflow 600 bench)with a six pak intake and carbs, it made peak power at 5800 RPM the last time it was on a engine dyno and peak torque at 4600 RPM. I switch the heads to a set of Indy SR max wedge ports that flowed 350 CFM at .700 lift on the same flow bench as the Eddy RPM, the peak HP is now at 7000 RPM and peak torque was at 4800 RPM The car use to cross the finish line in the 1/4 mile at 6200 RPM with the old heads and intake system and now crosses at 7000 RPM with the Indy 400-3 intake and a single Holley 1050 CFM Dominator, no other changes I say use the cam you got to start with and see if you like the results
on my 440-6
from the eddy,s rpm to the indy sr,s how much more power did you gain
I have a set of stage six heads and would like to try indy sr,s that are max wedge ported with the indy tunnelram six pack setup im working on
1.39 9.85 - 137 mph
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Re: Cam duration vs cubic inches
[Re: Cab_Burge]
#1082433
09/26/11 12:58 AM
09/26/11 12:58 AM
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Joined: Jan 2007
Posts: 3,695
nc
emarine01
OP
master
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OP
master
Joined: Jan 2007
Posts: 3,695
nc
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Quote:
Quote:
Wow, that's 300 more rpm drop than my best guess So If we apply the 1* per 10 cube rule 360 to 408 lets say 5* more duration, about how much will rpm rise?
I'm a racer and engine assembler, not a engine sceinintest(SP ) or theoryist I can call Comp Cams race dept. tomorrow and get their engineers involved, if you want, That is who I use on new engine combinations for racing, PM me with more info on your total combination
Thanks for the offer but I am just trying to apply some hard learned info for some easy answers.... or if there are any rule of thumb type answers that are even close to real world results...Sometimes these threads produce some real good info with the math to back it up sometimes not,But its all part of the learning curve, Thats what makes Moparts so cool... the diversity and knowledge of its members  Also I did mention I was bored 
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Re: Cam duration vs cubic inches
[Re: emarine01]
#1082434
09/26/11 01:24 AM
09/26/11 01:24 AM
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Joined: Nov 2003
Posts: 5,160
Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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We know the 360 has to turn 7500 to produce the peak hp. In 7500 revolutions the 360 ci engine moves 2,700,000 cubic inches of air. The 408 will move the same amount of air in 6618 revolutions. May not be exact but I bet it is close. A friend did this with a truck. He built a new 408 short block and used all the parts off his 360. Truck was about a tenth faster and that was it. He had to lower his shift points.
Getting old just means you were smarter than some and luckier than others.
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Re: Cam duration vs cubic inches
[Re: dannysbee]
#1082435
09/26/11 01:38 AM
09/26/11 01:38 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
We know the 360 has to turn 7500 to produce the peak hp. In 7500 revolutions the 360 ci engine moves 2,700,000 cubic inches of air. The 408 will move the same amount of air in 6618 revolutions. May not be exact but I bet it is close. A friend did this with a truck. He built a new 408 short block and used all the parts off his 360. Truck was about a tenth faster and that was it. He had to lower his shift points.
IMO.. this is the way to look at it... its a percentage
of increase(everything in a car is a math formula)
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