I can't seem to get a definitive answer to this question so I thought I would post it here.

Which of these two cams are theoretically bigger?
The engine with cam 1 is 350 cubic inches.
The engine with cam 2 is 388 cubic inches.

Both engines are LT1/LT4 based.

Cam 1.

Lift 59X-59X
Duration at 0.050 242-248
LSA 113+4

Cam 2.

Lift 62X-63X
Duration at 0.050 248-254
LSA 110+4

I do not have the advertised lift numbers.

 

What do you mean by bigger? #2 clearly has more area under the (lift) curve. That's what most people mean by "bigger". Do you mean rev range as installed in the two motors? They would probably be about the same in typical setups.

Rich

 

Just out of curiosity... how did you shrink the LT1 to 348ci?

 

LS1 = 348ci

Cam 2 is definitely a bigger cam, but might provide a better combination with the extra cubes of the engine. This is assuming all the supporting mods are there. You might need a higher stall/steeper gears for the larger cam.

 

...hense my question.

 

Well obviously he's going to run a LS1 piston for lighter weight and a wider piston to wall clearance for that 500hp shot of nitrous!

Seriously, could just be a mental mistake. What springs were you planning on running with that second cam?

 

Ha ha, I corrected it to say 350, although I think the LS1 is 346 cubes?

So cam 2 is most likely bigger?

 

Define what you mean by bigger. Bigger is not always better when it comes to cams.

 

I agree bigger is not always better, I am just wondering in theory what cam is larger. I posed this question on LS1Tech and was informed there is more to it than the cubic inch factor. Head flow, compression, and other bolt on's like exhaust would have an effect. Although some have said cam 1 is bigger, most say cam 2.

 

More lift, more duration, smaller LSA all make a "bigger" cam. You should build the rest of your setup and then have a cam ground to match it. This includes everything you listed above and also what your goals are for the car.

 

I think everyone is confused by your post. First of all, the statement "most likely bigger" doesn't make sense, since it is easy to tell from the spec's which one is "definitely" bigger. A cam is not larger "in theory".

Secondly, cam 2 had more duration and more lift. How can you NOT tell that it's bigger?

Both seawolf and rkrause asked you to define bigger, but you haven't.

By the way, Donnie, I'm leaving for Texas in 2 weeks, so we really need to finish up your motor next weekend.

Mike

 

I should have worded the question more clearly. I understand what your saying. Total performance and driveability aside, my question is what cam is larger when you factor in the cubic inches.

My question may be more understandable with the following example:

A 220-220 cam on 350 inches would theoretically be bigger than a 224-224 cam with 700 cubic inches...follow the logic? This is my question.

rkrause asked if I was wondering what would rev out more as this would represent its size in comparison to the cubes it would be running. So this would also be my question. Sorry for the confusion.

 

If you're talking about rpm range, then cam 1 will have a higher rpm range. Both cams close the intake valve at 50 deg ABDC. IVC is the most influential cam spec that determines rpm range. With both cams 1 and 2 having the same IVC, the one with less cid will have a higher rpm range, and that would be combination 1.

HOWEVER, rpm doesn't necessarily mean hp. You see combo 2 has more cid, more cam duration, and more lift. It will make more hp, but at a lower rpm. Cam 2 has 12 deg more overlap, so it will lope more and also get more air through the motor and produce more power.

 

Thanks!

 

I pretty much agree with Mike. I would add that IF everything else, especially the heads and the CR were EXACTLY the same the peak hp would be about the same with the smaller motor making the hp at SLIGHTLY higher rpm. The bigger motor would have more torque. Gear appropriately, there wouldn't be much difference between 1/4m. times as the smaller motor could use more gear. The bigger motor would make a nicer street combo, but they would be pretty damn close.

Why do you ask?

Rich