[08GOGT]

I think I have it narrowed down to one of these two that I want to get. Both sound good but I think the hot rods have a little better. Does anyone know which one will gain me more power? I bought my intake and tuner from bamachips so I plan on getting the tune from them. Also are you able to rent the special tools from a o'riellys or autozone or where do you guys get the tools from without having to buy them?

 

[07stanggt]

What do you mean by hot rods have a better sound? If you mean more lope. Not even close. Thumprs hit harder then hot rod cams.

For power here is a dyno, same car comparison. Hot rods are red, thumprs are green.

You need gear with thumprs. Really, 4.30s. But at minimum 4.10s. Hot Rods are probably a better street daily driver cam. Thumprs have a nastier idle and are going to be a better race cam. Meaning in the race range of the rpm band, they make a lot more power.

 

[pear0119]

I got the Hot Rods, well for me this was the better choice as I do most of my driving in the city and they were just the better choice for what I wanted my car to be.

If you visit the track often then the Thumprs would be the better choice but if you never go to the track like me and do a lot of city driving then the Hot Rods IMO would be better. With that being said it really comes down to how you are going to use the car, everyone uses their car differently.

The graph Rich posted was the selling point for me as I wanted cams that wouldn't net me much HP loss down low in the RPM range.

 

[IronStomach]

Hot Rods are probably a better street daily driver cam.

Just out of curiousity, never having driven a car with aftermarket cams, why would the Hot Rods be preferable for a daily driver over the Thumprs? Why are the race cams so unpreferable for a daily driver?

 

[TheUNZippee!]

Because the more aggressive a camshaft profile is, typically the more it starts to lose power lower in the rpm range, which is what affects normal daily driving.

 

[IronStomach]

Because the more aggressive a camshaft profile is, typically the more it starts to lose power lower in the rpm range, which is what affects normal daily driving.

Ok, that makes sense. So like Rich said, gears to pair with the powerband.

 

[TheUNZippee!]

Yes.

Did we at one time or another have a discussion regarding camshafts and how they work?

 

[IronStomach]

Yes.

Did we at one time or another have a discussion regarding camshafts and how they work?

Yes. Some thread about technical info that got tossed in the mega tech info sticky. That thread helped me understand engines. Prolly all I'll retain until I actually rip one apart, but it helped.

Though I'm having a hard time rationalizing how a cam can make more power at faster engine speeds while decreasing power at slower engine speeds.

 

[TheUNZippee!]

Because by the very nature of the camshaft's purpose- to allow air/fuel mixture in to the cylinder- in order for it to do more of that, it affects power down low.

Meaning: As we discussed, the camshaft opens and closes the valves. In order for the camshaft to increase power, we typically order a camshaft that does two things:

It opens the valves further, and for longer. This increases valve overlap (the time during which the intake and exhaust valves are open at the same time), and can in extreme cases also affect vacuum. This results in a rough idle, and a engine that cannot fully utilize the extra air fuel provided until higher in the rpm range.

Lobe separation angle can also affect where the power is made. Wider means power higher in the rpm range, more narrow LSA means better power down low.

Another factor in all this is how a different camshaft affects cylinder pressures. A lumpy cam with a wide LSA will see lower cylinder pressures.... and thus less power down low.


LSA is the distance in degrees that the intake and exhaust lobes are separated on the camshaft. Measured at the peak point of lift.

 

[07stanggt]

Because the more aggressive a camshaft profile is, typically the more it starts to lose power lower in the rpm range, which is what affects normal daily driving.

:withhomo

if you look at that dyno the Thumprs lost significant low end torque, like 30lbs or something, now thats with no tuning so that could have been fixed a little bit. But you are going to feel that loss driving around on the street. When you are racing, you shift at 6500, lets just say, your rpms drop to 5100 so you really dont care what the power band is like a 2000rpm. You want the most power in the race rpm range you can get for a faster car. And as you can see in that rpm range the Thumprs make a lot more power then the Hot Rod cams. A lot, average that out you are probably looking at 2/10s. But on the street you care about the low end.

 

[IronStomach]

Thanks you two. I need to study Zip's post.
Starting to make a lot of sense though.

 

[TheUNZippee!]

Cam Specs & Effects, duration centerline separation and lift, more on pereformance engine parts

 

[demon-cleaner]

Thanks you two. I need to study Zip's post.
Starting to make a lot of sense though.

+1. I need to study Zips post closer, but I can't stop watching the sweet ass avitar!

 

[TheUNZippee!]

whoopsie!