[v606er]

what is the difference between the push rod(i think the vette zo6 has them) and the dohc/sohc(our cars)

[ReverendDexter]

entirely different engine design.

Pushrod has a single cam in the block.

SOHC has a single cam in each of the cylinder heads.

DOHC has two cams in each of the cylinders (one for intake, one for exhaust).

[ReverendDexter]

In terms of performance, pushrod motors are usually torquier, and OHC designs will rev higher and be more hp oriented.

OHC designs are usually more efficient.

[v606er]

Originally Posted by ReverendDexter entirely different engine design. Pushrod has a single cam in the block. SOHC has a single cam in each of the cylinder heads. DOHC has two cams in each of the cylinders (one for intake, one for exhaust).

o. i assume the pushrod is better cause the z06 is faster... but which one is actually better?

EDIT: ok well that answers my question. i guess we posted at the same time

[ReverendDexter]

Chassis aside, the Z06 is fast for two reasons:
1) The LS-series are the most efficient pushrod motors ever made.
2) The LS7 is 7 liters... as in 427 cubic inches.

[RandoGT]

Originally Posted by ReverendDexter Chassis aside, the Z06 is fast for two reasons: 1) The LS-series are the most efficient pushrod motors ever made. 2) The LS7 is 7 liters... as in 427 cubic inches.

with that said, (hypothetically speaking of course) if Ford was to take their 4.6 and say "hey, let's make it a 7 liter", use the same technology as the LS7, same grind cam, head ports alike, everything...which one would make more power?

2nd option. if the 4.6 was to be upped to a 5.7 (to match the LS1), leaving it as is, how would they match up powerwise?

[Eagle2000GT]

Originally Posted by RandoGT with that said, (hypothetically speaking of course) if Ford was to take their 4.6 and say "hey, let's make it a 7 liter", use the same technology as the LS7, same grind cam, head ports alike, everything...which one would make more power? 2nd option. if the 4.6 was to be upped to a 5.7 (to match the LS1), leaving it as is, how would they match up powerwise?

Ford already has (had?) a 7 liter pushrod engine. It was the 428 Cobra Jet and they used to put them in Mustangs. They changed to the modular motor for a more efficient manufacturing process.

If you want a 5.8 modular motor, MMR has the block for you. Scroll down about half way.

Modular Mustang Racing

[qwik48r]

Originally Posted by ReverendDexter In terms of performance, pushrod motors are usually torquier, and OHC designs will rev higher and be more hp oriented. OHC designs are usually more efficient.

just FYI... ALL GM trucks and SUV's between 1999 and NOW all have LS series engines. i have a 4.8 in my truck which see's 7000+ rpm every weekend... stock motor, just upgraded vlaves springs... 20 minute chore.
in all fairness, if built correctly (actually balanced... or at least halfway...)most any OHV V8 motor will spin just as well as any OHC V8 motor.

i like to think about like this: every GM vehicle with 5.3 to a 6.0 ls v8...
all you need is a cam/spring swap, good exhaust (as in NO manifolds or shitties) and tune and 100 extra hp can be had.... out of any LS... with any miles... 6 bolt mains, cathedral cylinder heads, stock internals can withstand upwards of 700 hp and 20+# of boost.................................... hows that for some chevy knowledge...

[qwik48r]

Originally Posted by Eagle2000GT Ford already has (had?) a 7 liter pushrod engine. It was the 428 Cobra Jet and they used to put them in Mustangs. They changed to the modular motor for a more efficient manufacturing process. If you want a 5.8 modular motor, MMR has the block for you. Scroll down about half way. Modular Mustang Racing

and ford actually had a 427... called it a side oiler. put it in the cobra... actually ford came out with the 427 first... a original 427 Sideoiler block is worth about 5 grand now in good condition... have a buddy thats got an original sitting in his shop right now... its got a busted main bearing valley... once he gets that welded... its going in a factory five for some lucky bastard....

[v606er]

Originally Posted by qwik48r and ford actually had a 427... called it a side oiler. put it in the cobra... actually ford came out with the 427 first... a original 427 Sideoiler block is worth about 5 grand now in good condition... have a buddy thats got an original sitting in his shop right now... its got a busted main bearing valley... once he gets that welded... its going in a factory five for some lucky bastard....

they are selling roush 427s where i am

[qwik48r]

yea they arent 427 CUI motors.. just 427 hp..

i m talking about the 427 s.o made in the 60's (started in 64' with the cobra.. after the 289 lol)... then chevy decided to make a 427 and put it in the vette

[ReverendDexter]

Originally Posted by v606er they are selling roush 427s where i am

Yeah, those aren't named for their displacement.

Ford also had a SOHC 427 or 428 (I forget which) back in the 60s that was going to be used as a NASCAR motor.

If you were to take a current 3v 4.6L and scale it up to a 7.0L, assuming no efficiency gained or lost, it would make ~466 hp. Scaled up to a 5.7L it would make ~372 hp.

OHC designs are more optimal for rpm due to the reduced oscillating mass. You're not fighting the extra intertia of the pushrods & lifters to actuate your valves. I've also yet to see an OHV motor with more than 2 valves per cylinder (if my memory serves, 5v motors are mathematically the most efficient design you can have - which is why Ferraris use 5v motors, as did the top-end Toyota 4A-GE).

If you think that a OHV motor can rev, compare the most advanced pushrod motors in the world (NASCAR engines) with the most advanced OHC engines (Formula 1). Nascar motors turn 10-11k rpm (if I recall correctly, please correct me if this is wrong). F1 motors turn 17-19k.

OHV motors do have their advantages, too. Their compact heads allow a much larger displacement motor to occupy the same amount of space: a DOHC 4.6L is the same size externally as a 429 or 460. This means you can have a LOT more torque in a smaller package, and keep the rpms down (which in turn leads to motor longevity).

[v606er]

i heard about that engine ford made that was supposed to be for nascar, but it was too good or something

[v606er]

why the push rod if ohc's are better(thats what i got out of your last post), then why is there the pushrod?

[Doc8224]

The OHC heads aren't that compact. A 4v 4.6 is alot wider than a big block. If you compare a cobra motor next to a LS-7 the ls motor will look like a baby and it is mostly the heads. As for power to size. a 5.0 cammer (dohc 5.0 modular from FRPP) is over 400hp and thats with about 302ci. The power in the OHC motors is in the heads. The 2v's can make torque to compare with a pushrod motor but the 4v's make the HP but need to rev high to do it. GM has a great motor in the LS and the mod motor is a love or hate thing. There is alot of power to be had in them but the cost can be high. You can make 450whp with a 4v with alot less cubes than the LS has.

[v606er]

i am really confused. what do the 2v or 4v mean? is that v6 and v8?

[Doc8224]

2v head or 4v head.

[Doc8224]

4v head. Like on the cobra and Mach motors. 4 valves per cylinder


2v head like on the Mustang GT's. 2 valves per cylinder

[qwik48r]

Originally Posted by ReverendDexter Yeah, those aren't named for their displacement. Ford also had a SOHC 427 or 428 (I forget which) back in the 60s that was going to be used as a NASCAR motor. If you were to take a current 3v 4.6L and scale it up to a 7.0L, assuming no efficiency gained or lost, it would make ~466 hp. Scaled up to a 5.7L it would make ~372 hp. OHC designs are more optimal for rpm due to the reduced oscillating mass. You're not fighting the extra intertia of the pushrods & lifters to actuate your valves. I've also yet to see an OHV motor with more than 2 valves per cylinder (if my memory serves, 5v motors are mathematically the most efficient design you can have - which is why Ferraris use 5v motors, as did the top-end Toyota 4A-GE). If you think that a OHV motor can rev, compare the most advanced pushrod motors in the world (NASCAR engines) with the most advanced OHC engines (Formula 1). Nascar motors turn 10-11k rpm (if I recall correctly, please correct me if this is wrong). F1 motors turn 17-19k. OHV motors do have their advantages, too. Their compact heads allow a much larger displacement motor to occupy the same amount of space: a DOHC 4.6L is the same size externally as a 429 or 460. This means you can have a LOT more torque in a smaller package, and keep the rpms down (which in turn leads to motor longevity).

its funny NASCAR small block makes about the same power as an F1 motor at half the rpms.... OHV's make there magic, in their heads


that was the 427 cammer your talking about


the less inertial mass is why they make more power up high... again OHV makes power in the head and chamber design correlating perfectly with the cam profile. OHC with less inertial mass, is ACTUALLY able to twist to 19K+, taking advantage of a different type of cam profile.. OHC motor generally can accomodate a more aggresive grind while still being tame...

we have a 383 here in the shop... actaully used to be a 2 bolt main we retrofitted after it flung a slug... got a set of Racer Pro's from Australia (cheap good head) and a monster bumpstick... we dual step it.. 5000 and th400 redline is set at around 10,000rpms

[ReverendDexter]

Originally Posted by v606er why the push rod if ohc's are better(thats what i got out of your last post), then why is there the pushrod?

Pushrods are an earlier design, easier to work on, cheaper to modify. And pushrods are pretty rare anymore when you look at cars on a global scale. American companies are the only ones that still sell a pushrod motor, and even then it's only GM and Chrysler.

If you give Joe America the choice between a 427 and a Turbo 3.8L, he'll take the 427 almost every time, even if the Turbo 3.8L makes more torque, more hp, and gets double the fuel economy.