Pontiac GTO Forum banner

1 - 20 of 27 Posts

·
Registered
Joined
·
4 Posts
OHC engines HAVE to be revved to take advantage of the engineering costs. They are always attached to small displacement engines, that produce modest HP unless they are zinged to the moon. Look at the tourqe curves on a OHC V8, pathetic. If engineering comes down to more with less, why add more? More in the case of OHC = engineering and manufacturing costs, weight, parts, paresitic drag, physical size, etc.
Wrong again Dave, ever heard of an Allison or Rolls Royce aircraft engine? They were OHC and didn't rev high at all . . . 3000-3200 rpm and they definitely made torque. Where the cam is located doesn't have anything to do with torque.:seeya

Allison V1710 Engine
 

·
Super Moderator
Joined
·
2,640 Posts
Discussion Starter #4
For a Moderator, you sure instigate alot of ****. lmao Twin Turbines FTW!
Thank you very much Mr. Sticks... LOL! As you can see from the smilie, I really mean no harm. I just think after some of the threads that went sour we should loosen up a little bit. ;)
 

·
Registered
Joined
·
44 Posts
No way man, turbine engines have to few moving parts, dont weigh enough, have to be spun to 100K rpm to make any power and are lame! They best turbine engines have pushrods, guide plates and gear drives, sheesh.


Lol, way to loosen things up man.

The fastest vehicle I have been in besides aircraft was a boat with a single turbine engine, 32' Skater tunnel hull owned by Howard Arneson. 160+ on the water was friggen awsome.
 

·
Registered
Joined
·
44 Posts
Stalwart, you have sunk to this level to prove me wrong? Wow. Aircraft engines? Provide a link to OHC engine that does all of the following -

Is lighter than a 7.0 litre Z06 engine
Gets better fuel economy than a 7.0 litre Z06 engine
Produces less emmissions then a 7.0 litre Z06 engine
Is physically smaller than a 7.0 litre Z06 engine
Costs less to produce than a 7.0 litre Z06 engine
Is more reliable than a 7.0 litre Z06 engine

I will leave it at that for now. This should keep you running in circles for a couple of years.
 

·
Registered
Joined
·
4 Posts
Stalwart, you have sunk to this level to prove me wrong? Wow. Aircraft engines? Provide a link to OHC engine that does all of the following -

Is lighter than a 7.0 litre Z06 engine
Gets better fuel economy than a 7.0 litre Z06 engine
Produces less emmissions then a 7.0 litre Z06 engine
Is physically smaller than a 7.0 litre Z06 engine
Costs less to produce than a 7.0 litre Z06 engine
Is more reliable than a 7.0 litre Z06 engine
Nope Dave, I'll not bite on that one. You were the one that said OHC's are essentially inferior, on that you are wrong. I'm going back to where I belong, Ford forums, I only have 6 BB Chevy engines and no GM cars: 2 naturally aspirated (one with NOS), 2 supercharged with 420 cid blowers and 2 with twin turbos. Your brother only saw the first 2 of 'em.:seeya:
 

·
Registered
Joined
·
199 Posts
Wrong again Dave, ever heard of an Allison or Rolls Royce aircraft engine? They were OHC and didn't rev high at all . . . 3000-3200 rpm and they definitely made torque. Where the cam is located doesn't have anything to do with torque.:seeya

Allison V1710 Engine
I read through that allison page you referenced. 60 degree V-12, SOHC, 4 valves per cylinder, 2 stage supercharger with 50/50 water/alcohol Anti-detonation injection (kinda like intercooling), up to about 1200 HP ... but I didn't see any torque specs. Just saying they made plenty of torque doesn't tell me anything. Of course a motor such as that will make "plenty of torque" ... but how does the HP/TQ ratio compare to a comparable pushrod v12?

It has been my experience, albeit anecdotal, that the typical OHC multi-valve motor produces about as much HP as it does TQ, whereas the typical pushrod motor produces about 1.2 to 1.3 times as much TQ as it does HP.

That being said, it's also been my experience that most of your high hp small displacement motors, (which can be VERY fun to drive, BTW) such as Mazda's 1.8L DOHC - 7500 RPM redline, produce their peak torque at a higher RPM than a more basic motor...
 

·
Registered
Joined
·
4 Posts
I read through that allison page you referenced. 60 degree V-12, SOHC, 4 valves per cylinder, 2 stage supercharger with 50/50 water/alcohol Anti-detonation injection (kinda like intercooling), up to about 1200 HP ... but I didn't see any torque specs. Just saying they made plenty of torque doesn't tell me anything. Of course a motor such as that will make "plenty of torque" ... but how does the HP/TQ ratio compare to a comparable pushrod v12?
3692 lb.ft. of torque, is that plenty enough . . .especially out of 1710 CID?
 

·
Registered
Joined
·
44 Posts
Stalwart

I understand the benefits of OHC cam engines and personely dont have anything against them. Hell, I think the ZR-1 DOHC engine and the Northstar sibling were two of the best engines to ever come out of GM. But they have there draw backs as well as benifits. The current LSX engines should not be looked down upon becuase they dont have cams located ontop of the heads, especially considering the price and reliabilty.


I have spent alot of time on other boards watching employees ( people paid to post) of forigne manufactures tear down US products and have a hard time letting go of the attitude when I post on pro US sites like this.

Sorry for the attitude.

By the way, I know your Shelby will spank my IROC, but would love to run it anyway. Atleast before I install the AFR's and larger cam.
 

·
Registered
Joined
·
199 Posts
3692 lb.ft. of torque, is that plenty enough . . .especially out of 1710 CID?
Good God! ... Nice number, but again, how does it compare with a comparable pushrod v12? If there aren't any, perhaps there are lesser motors (v8's or v6's) that could be compared.

since the discussion referenced the relative merits of pushrod over OHC, I think all of the anecdotal evidence in the world will not prove one side or the other. The only thing that will would be comparable motors, one being pushrod, one being OHC, with similar displacements (and bore x stroke), compression ratios, fuel delivery systems, induction systems, ignition systems, cam lift/duration, and valve size / number.
 

·
Registered
Joined
·
1,448 Posts
Great information....really. I did not know there were 2 GTO's and I'm glad one survived.

Bumble Bee starting a out as a GTO is also a cool fact.
Thanks
 
1 - 20 of 27 Posts
Top