Good Cam Choice?

-
Dale Davies said:
Dan, for street you want a torquey engine to get you rolling off street lights and stop signs. Some of the commenators here live with HP up their hoop. Fine for them. A big HP engine will have a cam that provides higher RPM torque. That with higher RPM gives a higher HP figure, and that high HP allows you to drive at 150 to 200MPH. Not exactly street.
Then the arguement goes to a torquey engine making you smoke the tires every time you step on the throttle. Well maybe if you have no filter, but judiscious application of the loud pedal controls that. A torquey engine allows use of taller rear gears which enables better fuel economy. A torquey engine in a truck allows pulling a trailer with less throttle opening again giving better fuel economy.
If you go to show and shines and to the strip a couple of times a year, more gear can be tollerated.
The "RV" cam designation came about as the design gave slightly more duration and lift than the OEM cams, which allowed easier hill climbing in motor homes and trucks pulling a holiday trailer. Then motor homes and trailers got bigger and that market moved to diesel engines, and diesels provide great low RPM torque for those working applications.
Click to expand...
Hp happens at every rpm not just peak. No one is just saying peak hp only matters, it's the hp created at every point in an engines powerband from idle to redline that moves your car.
 
Dale Davies said:
Kinda so. But HP is the result of torque, and torque does the acceleratiing.
Click to expand...
The end result of torque and rpm, torque and rpm what moves and accelerates your car which hp, a running engine always outputs torque and rpm (power) why do you guys keep on insisting to separate these two functions. No one talks like this about watts volts and amps, it's understood a circuit has power running through it which is a combination of volts and amps, same goes for hp and torque and rpms.
 
srduster340 said:
My 414 Duster has a Comp flat tappet with specs of 242/250, 106 lsa, 107 ic installed, weighs 3300, 3.55 rear, 28" tires & 4 speed. Makes killer low end & mid range but is done @5400. I have FiTech efi, air gap intake. Timing was locked out @ 34 degrees & was a dog on the low end with a carb. Switched to efi which controls the timing now & it feels like a different car with the increase in low end power. I can be cruising on the hwy @2500 in high gear and floor it. No hesitation, pinging, it just gets up & hauls. Takes a little more rpm when taking off with the stick but so much fun to drive. The thing I love about this combo is from 3000-5400 the torque is at least 450ft;lbs. Peaked 510@3900. I'm sold on the narrow lsa.
Click to expand...
That sounds like a great combo. Im glad you like it. Self Tune or did someone tune it for you.
 
Dale Davies said:
What is the intake valve size. Using 2.05" in the 128 formula indicates a 102 LSA. Pretty tight so I would order the cam ground on a 108° LSA.
For the intake manifold it depends on what you expect for street manners. The Performer AirGap will provide a little better off idle torque, but with the 3.91 gearing the Victor should work well as the revs will pick up quickly.
Click to expand...
They have a 2.08 intake. When I did the equation, it said I should use a 106. From the input, sounds like that is still too tight for my application so I will probably do with something a little wider
 
Newbomb Turk said:
It depends on how many compromises that can be put up with, and really it comes down to how much work goes into doing it. Most guys won’t do the work to build something they can’t see done on a forum.

Then there is the tuning aspect. And that’s all I’ll say about that.
Click to expand...
The guy that tunes mine is really good. There are a lot of good tuners in the holley world.
 
Dale Davies said:
With an exhaust O2 sensor the tighter LSA increases overlap which can allow unburned fuel to get out the exhaust during the overlap period. The O2 sensor sees this as a rich condition and tries to lean it out. Throttle body injection is more difficult. With multiport the beginning of injection can be tuned to reduce that.
Click to expand...
That makes sense, thanks for the info.
 
siuauto said:
That makes sense, thanks for the info.
Click to expand...
Just a thought here; DV just released a Polyquad 4 valve discussion video. Now I realise the SBM is a 2 valve, but pick tidbits where you can. If you sink the exhaust valves about 0.100", the exhaust is almost closed when the intake opens and the inkake air/fuel skips over the exhaust valve head instead of some finding its way out the exhaust. Also 40° exhaust seats allow blowdown quicker in like manner to back cutting the intake valves. This helps reduce pumping losses as the piston rises on the exhaust stroke. If using headers it also increases the strength of the pulse tuning. Could help with tuning the EFI and keeping the O2 happy.
 
Dale Davies said:
Just a thought here; DV just released a Polyquad 4 valve discussion video. Now I realise the SBM is a 2 valve, but pick tidbits where you can. If you sink the exhaust valves about 0.100", the exhaust is almost closed when the intake opens and the inkake air/fuel skips over the exhaust valve head instead of some finding its way out the exhaust. Also 40° exhaust seats allow blowdown quicker in like manner to back cutting the intake valves. This helps reduce pumping losses as the piston rises on the exhaust stroke. If using headers it also increases the strength of the pulse tuning. Could help with tuning the EFI and keeping the O2 happy.
Click to expand...


40 degree exhaust seats? If true, that’s as *** backwards as it gets.
 
Dale Davies said:
Dan, for street you want a torquey engine to get you rolling off street lights and stop signs. Some of the commenators here live with HP up their hoop. Fine for them. A big HP engine will have a cam that provides higher RPM torque. That with higher RPM gives a higher HP figure, and that high HP allows you to drive at 150 to 200MPH. Not exactly street.
Then the arguement goes to a torquey engine making you smoke the tires every time you step on the throttle. Well maybe if you have no filter, but judiscious application of the loud pedal controls that. A torquey engine allows use of taller rear gears which enables better fuel economy. A torquey engine in a truck allows pulling a trailer with less throttle opening again giving better fuel economy.
If you go to show and shines and to the strip a couple of times a year, more gear can be tollerated.
The "RV" cam designation came about as the design gave slightly more duration and lift than the OEM cams, which allowed easier hill climbing in motor homes and trucks pulling a holiday trailer. Then motor homes and trailers got bigger and that market moved to diesel engines, and diesels provide great low RPM torque for those working applications.
Click to expand...
Again, you’re confusing Dan. Torque does not move a car. Never has.

If that were the case, we’d all be running diesel engines.
 
273 said:
Hp happens at every rpm not just peak. No one is just saying peak hp only matters, it's the hp created at every point in an engines powerband from idle to redline that moves your car.
Click to expand...

Thats the argument they use to prop up their bad theory.

I’ve never seen anyone run a car based on average torque. It’s average horsepower that moves the car. The more gears the more critical it is.
 
Newbomb Turk said:
Vizard tried to sell the 30 seat nonsense probably 30 years ago.

Anything less than a 45 is just dumb. Some of us have caught up to 2001 and we use 50 degree seats. And make more power doing it, regardless of how much lift you use.
Click to expand...
OK. Explain why or how 50° seats make more power.
 
To claim a 30* intake seat is useless is just ignorant. The 30* intake seat is beneficial to about 400-450 lift. High hp engines are using more than 450 lift.....
Many folks will use a lower valve lift for a variety of reasons. Working to a budget, cannot afford new springs/head work for more valve lift, happy with a modest hp increase, want to reduce stress on the valve train, etc.

See below, Edelbrock Pontiac head converted to 30* seat.
 
RustyRatRod said:
It straightens out the flow path more. I'm sure there's a point of diminishing returns.
Click to expand...
They also wedge the valves in the seats more preventing valve bounce and promoting better seal.
As with everything there is benefits and disadvantages. In some situations the situation is skewed more in favor of one or the other.
The 40° favors lower total valve lift by getting more at the low lift.
 
Try again for post #140

img340.jpg
 
Bewy said:
To claim a 30* intake seat is useless is just ignorant. The 30* intake seat is beneficial to about 400-450 lift. High hp engines are using more than 450 lift.....
Many folks will use a lower valve lift for a variety of reasons. Working to a budget, cannot afford new springs/head work for more valve lift, happy with a modest hp increase, want to reduce stress on the valve train, etc.

See below, Edelbrock Pontiac head converted to 30* seat.
Click to expand...

LOL. Yeah, everyone is using 30 degree seats because it’s the hot ticket.

It never was and never will be a performance valve job.
 
siuauto said:
That sounds like a great combo. Im glad you like it. Self Tune or did someone tune it for you.
Click to expand...
I tune it myself. Still learning though. Took a while to get it to stop stalling when I would turn a corner. Turns out it was the IAC steps.
 
Of course in Newbomb's world, only 45* or larger makes more power. In the real world, it is different.....
MM Muscle magazine did an in depth porting exercise on BBM heads, about 20-25 yrs ago. Spread over a few issues. I have them, have to dig them out. Pretty sure they went to a 2.14" intake valve & 30* seat....& got more flow.
 
Bewy said:
Of course in Newbomb's world, only 45* or larger makes more power. In the real world, it is different.....
MM Muscle magazine did an in depth porting exercise on BBM heads, about 20-25 yrs ago. Spread over a few issues. I have them, have to dig them out. Pretty sure they went to a 2.14" intake valve & 30* seat....& got more flow.
Click to expand...
If that was the Dulcich exercise, He's abandoned that altogether. It's not the lift that's key there, it's the duration seat-to-seat that's the limitation on a 30°vj, like Newbomb said...it's a flowbench "lie". Anything significant over a mild stock cam, say the avg. Factory HP, will experience reversion & lose more Hp than the "flow" will gain...
 
Bewy said:
Of course in Newbomb's world, only 45* or larger makes more power. In the real world, it is different.....
MM Muscle magazine did an in depth porting exercise on BBM heads, about 20-25 yrs ago. Spread over a few issues. I have them, have to dig them out. Pretty sure they went to a 2.14" intake valve & 30* seat....& got more flow.
Click to expand...


And lose power doing it. Geezus, step up to the 1970’s and forget they ever made a 30 degree seat.
 
You must log in or register to reply here.
-

Back
Top