|
Pick me a cam
#1391155
02/20/13 10:26 PM
02/20/13 10:26 PM
|
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
1_WILD_RT
OP
Management Trainee
|
OP
Management Trainee
Joined: Jan 2004
Posts: 27,347
Today? Who Knows?
|
I'm playing around with the idea of a cam swap in my Challenger, nothing big just hoping to optimize what I have.. The Car... !970 Challenger R/T Vert.. Heavy probably 3700lbs 3.23 gear which is staying, this is a highway cruiser not a hotrod 727 with stock convertor currently it with flash 2200ish Stock exhaust manifolds to tips Stock A/C, going to change to a Sanden compressor The Engine... Original 383 with 75K miles since O/H .030 O/S KB 162 pistons .018 in the hole 5cc valve trough with the current 906 heads C/R is around 8.2-1 But I'm changing to a set of 915 heads which have been cut .030 which reduced chamber volume to 76cc New C/R should be 9.7 Current cam is the OE Resto cam Intake is a Performer RPM & Carb is a Holley 4776 600cfm D/P I've jetted it down four sizes & opened the PVCR's I know the official stance is a heavy car with tall gears should have a vacuum secondary carb but it runs well & I accept the fuel mileage.....  So lets hear your thoughts...
"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."
|
|
|
Re: Pick me a cam
[Re: RoadRunnerLuva]
#1391160
02/21/13 10:24 PM
02/21/13 10:24 PM
|
Joined: Aug 2005
Posts: 4,800
ILL
MLR426
master
|
master
Joined: Aug 2005
Posts: 4,800
ILL
|
Quote:
Quote:
From the VooDoo line I would say a 60302
 with Pacnorth....this cam would work
well with your combo IMO....makes good power
from 2000-5500 rpm.
XE268H Comp Has a wider operating band than the Voodoo 
MLR426
|
|
|
Re: Pick me a cam
[Re: 1_WILD_RT]
#1391161
02/22/13 02:32 AM
02/22/13 02:32 AM
|
Joined: Jul 2008
Posts: 259
Khemi, Stygia
Mebsuta
enthusiast
|
enthusiast
Joined: Jul 2008
Posts: 259
Khemi, Stygia
|
I don't know. Relative to other cams its size, the OE resto cam has late intake valve closing, early exhaust opening. In theory, I think you need pretty high compression, and it kind of lends itself to high rpm operation in 383.
I use it. It's trouble-free but not spectacular. If I try another, I will use something that closes intake sooner and traps more cylinder pressure, like old single-pattern Comp 268H or Erson tq20h, or a copy of something like that.
Well, since you are changing to closed chamber heads, see what it does with increased compression before you change cams.
68 Roadrunner. 383 4-spd. Beat up.
|
|
|
Re: Pick me a cam
[Re: RoadRunnerLuva]
#1391165
02/22/13 01:18 PM
02/22/13 01:18 PM
|
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
Quote:
Quote:
From the VooDoo line I would say a 60302
with Pacnorth....this cam would work
well with your combo IMO....makes good power
from 2000-5500 rpm.
X3.....yes this cam has less .050 duration than the XE268, but it probably has similar .2" duration, for similar max power potential, while having an earlier intake closing point for more cylinder pressure and low RPM torque. the slightly wider lobe separation will also keep the torque curve flatter, and carry the HP high enough for most street hooliganing (~5500 RPM)
personally, I think most people overcam their cars....
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
|
|
|
Re: Pick me a cam
[Re: Dunnuck Racing]
#1391167
02/22/13 04:16 PM
02/22/13 04:16 PM
|
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
|
Personally, I prefer wider LSA's, it sacrafices a little bit of peak torque in exchange for more torque above the torque peak, so for a given duration, your powerband will be wider, and your torque curve flatter. I also like short duration, high lift cams. the XE268 is a .842" lifter lobe profile, but a very aggresive one. as a comparison, Bullet Cam's most aggressive .842" 226@.050 lobe is 270 adv, 226@.050, and 138@.2" with .326" lobe lift (.489 with 1.5 rockers)... their most aggressive .904" lobe with the same 226@.050 duration is 270 adv, 226@.050, and 142@200 duration with .335" lobe lift (.502" lift with 1.5 rockers, 4 degrees more duration over .2" lobe lift) and their least aggressive 226@.050 .842" lobe is 274adv, 226@.050, 127@.2, and .273" lobe lift.... so...to get similar .2" durations as the aggressive .842 lobe with a .904 lifter lobe, you can drop .050 duration down to 220@.050, or to the less aggressive .842 lobe, you can drop your .050 duration down to 212-214 degrees http://bulletcams.com/Masters/Hlobes.htmhttp://bulletcams.com/Masters/HClobes.htmI had an XE262 in a 360 running about 8:1, and it wasn't bad, but it was a little cranky at low speed, and idle was a bit more radical than I would have liked. that was with a MP166K converter, low gear 904 and 3.55's....don't think I'd want bigger than that in a daily driver/cruiser, personally.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
|
|
|
Re: Pick me a cam
[Re: patrick]
#1391168
02/22/13 04:42 PM
02/22/13 04:42 PM
|
Joined: Mar 2007
Posts: 3,300
Northern Indiana
Dunnuck Racing
master
|
master
Joined: Mar 2007
Posts: 3,300
Northern Indiana
|
The wider lsa / peaky torque curve idea is nothing more than a common misconception . I have proven it is a myth on several different builds as have several other people. A lot of guys still believe intake closing points are the main thing to look at too,but that is 80's technology being passed down. I just tested a few different cams with the intake closing point being nearly identical , moderate duration,and varying lsa in a mild 360. The best overall torque curve was the narrowest lsa Keith
|
|
|
Re: Pick me a cam
[Re: Dunnuck Racing]
#1391169
02/22/13 05:30 PM
02/22/13 05:30 PM
|
Joined: Jun 2006
Posts: 5,187
CT
GTX MATT
master
|
master
Joined: Jun 2006
Posts: 5,187
CT
|
Quote:
The wider lsa / peaky torque curve idea is nothing more than a common misconception . I have proven it is a myth on several different builds as have several other people.
A lot of guys still believe intake closing points are the main thing to look at too,but that is 80's technology being passed down.
I just tested a few different cams with the intake closing point being nearly identical , moderate duration,and varying lsa in a mild 360. The best overall torque curve was the narrowest lsa
Keith
Keith,
Do you think that as the duration grows relative to the displacement and overall aggressiveness of the build that a wider LSA will become more beneficial, assuming the same intake closing point? If you take a stock low performance .430 lift big block cam and change the LSA from 115 to 108 (I know you cant change LSA, but theoretically) I would think it would wake it up a lot merely because it would provide the engine with more overlap, and the overlap on that cam is so low. Take, for example, a 440 that had a single plane intake, headers, and a larger carb and head work. The thing would probably work best with an insanely tight LSA to compensate for the insane lack of duration.
Take a 509 cam and stick it in a 383 that's 100 percent stock otherwise and tightening up the LSA would kill it even more. Open it up and you'd likely see better overall performance due to the fact that now the thing isn't choking so much on the low end, and it didn't have the capacity to work the 509 on the top end with a 108 LSA. (Mopars theory on those new turdy 114 LSA cams since everyone complains the old school ones are doggy in stockish setups)
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
|
|
|
Re: Pick me a cam
[Re: BSB67]
#1391171
02/22/13 06:13 PM
02/22/13 06:13 PM
|
Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 16,376
|
|
|
|
Re: Pick me a cam
[Re: Dunnuck Racing]
#1391174
02/22/13 06:29 PM
02/22/13 06:29 PM
|
Joined: Feb 2004
Posts: 4,501
Gainesville,FL
goldmember
master
|
master
Joined: Feb 2004
Posts: 4,501
Gainesville,FL
|
Quote:
The wider lsa / peaky torque curve idea is nothing more than a common misconception . I have proven it is a myth on several different builds as have several other people.
A lot of guys still believe intake closing points are the main thing to look at too,but that is 80's technology being passed down.
I just tested a few different cams with the intake closing point being nearly identical , moderate duration,and varying lsa in a mild 360. The best overall torque curve was the narrowest lsa
Keith
We knew in the 80's(I'm sure others in the 50's did as well) the easy way to kill torque and hook a car up was to stretch the lobe centers. Car was a turd but easy to hook. Sticky tracks you'd better get out of the way or put the right cam back in it. I agree also that the wide lsa (broader power band)believers are way off track. Now if you must have 20"idle vac and run a tiny engine in a heavy car,yadda,yadda and don't know a strong performer you'll be happy with your results.With modern induction systems the cam requirements are not what the old tech stuff might prefer. As far a hyd cams go I am not a big fan of any .904 lifter stuff unless your RPM limited by some part of the build. The numbers on the cam tables are not what the engine will see when the hyd lifter gets confused. 
|
|
|
|
|
