i was wondering what is sohc, dohc, and pushrod. what is the performace related to thes and i know gm is pushrod but what is the mustang and viper. I own a 87 trans am so please be objective, it would be preaching to the choir. Also, what do you notice in performace when you increase torque as compared to increasing hp thanks

 

Let me be the first to welcome you to Thirdgen.org I've learned a lot here hopefully you will too.

To answer you question pushrod is what all of us have here on our f-bodies. Also call over head valve.
Double over head cam is in the stangs as you mentioned as well as many new cars these days. These cars have two cams, one top of each head. sohc is just one cam but instead of being buried in the block like the overhead vlave (OHV) its on top of the head.
as far as increasing torque vs. HP, well, HP is only a function of TQ, i forget the exact equation I am sure someone knows, i think is
hp=(TQ)(RPM)/5500

something like that, so when you increase one you are bound to increase the other.
Again welcome.

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i saw that formula, but then why do some cars have the same horse but half the torque my cars has? And these differnat cams whats the trade off? i see that the dohc would have to be used in a v engine and the sohc are probably only for inlines, but what about pushrod/ohv vs dohc

 

A DOHC engine has 2 cams in each head, however many there are; one for the intake valves which are usually over on one side of the head where the intake and fuel injectors and such things are, and one over the exhaust valves, which are (duh) on the side where the exhaust goes. A DOHC V8 would actually have 4 cams, 2 in each head.

A push rod motor has the cam down in the block, with the lifters riding on it, and the push rods sit in those and get pushed up; there are rocker arms on top of the heads at the other end of the push rods, which push the valve down (open) when the cam raises the lifter.

Horsepower doesn't really exist. It is a mathematical creation to express the time rate of doing work. Torque is a measure of how much work the engine is capable of doing (how hard it can push, or twist, something). Horsepower is the product of torque and RPM and a constant related to the definition of horsepower (one HP = raising 33,000 lbs one foot in one minute). Since HP is a function of this product of the 2 numbers, an engine can have very high torque but low horsepower (think of a tractor motor) or low torque but very high horsepower (a Formula One motor), according to whether its torque output is at a maximum at low or high RPMs. I'm reminded of a tractor I once had that had enough torque to pull down a building, but was rated at only 65 HP; on the other hand, it wouldn't go faster than about 2500 RPM.

Since torque is what actually moves the car, you could have 2 engines with similar HP ratings (say, a Maxima or Lexus and your Formula) but vastly unequal performance, since their torque output is so different. The Maxima engine can't push the car nearly as hard as your V8 (lower torque) and therefore won't be nearly as fast, but it can continue to produce meaningful power at a much higher RPM than yours can because its cylinders are so small compared to the passages that feed them, which helps when passing on the highway or the like. The product of its lower torque at a higher RPM produces a similar HP number to your car.

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"So many Mustangs, so little time..."
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ok i think i get it thanks

 

umm two cams per head is called dual twin cam actually, DOHC just implies two cams i would say. ive only seen a dual twin cam once, crazy stuff, it was on a cutlass supreme, early 90's