CAMS!!

[ARRESTmeRed04]

ok, what are the limitations(spelling?) on our factory valvetrains?? as far as lift and so on, i'd like a cam but i 1. want more than 8-10hp(i've hear thats all you get from the 708) 2. don't want to spend 2k to change it 3.is there any other choices out there that offer maybe 25hp with the factory valvetrain???

 

[kyle's srt10]

Let me tell you from my experence on the cam swap. I got talked into buying one from GARY he was really good at that:dontknow: I got the 708 cam and ended up going with a comp cam and hardend pushrods I done some smoothing and gasket matching to the heads:rock: I have a really nice lope at idle especially with the SC'r now My cam should benefit me more with the blower than it did NA So let me tell you unless you plan on some ported and polished heads and some shaft mounted rockers like T&D's don't waste your $$$ on the cam swapI believe I have a little over 2k in my swap and HOURS of grinding,smoothing and prolly only gained 15rwhp on my NA tune If you want to go ahead with the swap get with Joe at PPJ for sure:rock:

 

[rottenronnie]

ok, what are the limitations(spelling?) on our factory valvetrains?? as far as lift and so on, i'd like a cam but i 1. want more than 8-10hp(i've hear thats all you get from the 708) 2. don't want to spend 2k to change it 3.is there any other choices out there that offer maybe 25hp with the factory valvetrain???

25 H.P with the o.e.m. heads?...I kind of doubt it.

25 or more with properly ported heads or aftermarkets is quite likely. I gained 30+ with a cam that matched the heads I used, more closely than the o.e.m. cam.
The o.e.m. cam that comes with our trucks is matched quite closely to the heads (which is what you want to do regardless of which cam you choose) and that is why there is a relatively low performance boost (say with the 708) when that is your ONLY change. The o.e.m. is a decent cam already.

It is quite a bit of work to change a cam just for a different sound. And if you get one that is too big, it won't be much fun to drive.

 

[Yellow venom]

25 H.P with the o.e.m. heads?...I kind of doubt it.

25 or more with properly ported heads or aftermarkets is quite likely. I gained 30+ with a cam that matched the heads I used, more closely than the o.e.m. cam.
The o.e.m. cam that comes with our trucks is matched quite closely to the heads (which is what you want to do regardless of which cam you choose) and that is why there is a relatively low performance boost (say with the 708) when that is your ONLY change. The o.e.m. is a decent cam already.

It is quite a bit of work to change a cam just for a different sound. And if you get one that is too big, it won't be much fun to drive.

Hey Ron,I think we need some more elaberated info,atleast I would,LOL!, By goin to big what do you mean by not much fun to drive? too touchy or just poor performance? What did you do with your heads? port and polished the stock ones or all diff heads all together? Thanks for the info.:rock:

 

[ARRESTmeRed04]

thanks for the info, i'd have the heads ported and polished too i was just wondering why there were no gains. it seems these engines don't respond to mods well at all(with out spending 5K or more) i know they already put out close to or right at 1hp per cubic inch out or the factory and it's hard to get much more than that NA. i'd like to eventually get to at least 530rwhp NA and i plan on nitrous later on. what kind of money would i be looking at to reach the 530rwhp? i can do all the work(as far as pulling the engine and so on) my self and i plan on a SCT so i can have more than one tune.

 

[kyle's srt10]

thanks for the info, i'd have the heads ported and polished too i was just wondering why there were no gains. it seems these engines don't respond to mods well at all(with out spending 5K or more) i know they already put out close to or right at 1hp per cubic inch out or the factory and it's hard to get much more than that NA. i'd like to eventually get to at least 530rwhp NA and i plan on nitrous later on. what kind of money would i be looking at to reach the 530rwhp? i can do all the work(as far as pulling the engine and so on) my self and i plan on a SCT so i can have more than one tune.

Tim (vipertruck2933) had 535rwhp and 567rwtq out of his truck:rock: Joe at PPJ done all of his work I believe he had mentioned that it set him back between 5-6k:dontknow: He done a custom cam grind PP heads,intake,TB,and I think he was running t&d rockers:rock: I am sure he will peak in tomorrow morning to let you know more details:burnout:

 

[rottenronnie]

Hey Ron,I think we need some more elaberated info,atleast I would,LOL!, By goin to big what do you mean by not much fun to drive? too touchy or just poor performance? What did you do with your heads? port and polished the stock ones or all diff heads all together? Thanks for the info.:rock:

Joe,
A BIG cam can create a host of problems for a primarily street driven vehicle such as low vacuum during idle and low speed driving. This can create problems for some power brake systems (like little or no power assist), trigger misfire codes, really stink up the environment during idling (esp. with a cat delete system) from unburned or partially burned mixtures, "force" your engine to rev before it produces power; etc.
A high r.p.m. power gain (horsepower), due to a cam swap, will often be at the expense of low end torque which is what you should be concerned with in a heavy vehicle like our trucks. A cam that provides poor low speed torque will also kick the crap out of any gas mileage you might get now. And there are other concerns.... So a bad choice here will make things worse. It is a fairly big job to change the cam in these engines.

Cam technology has come a long way but it is still an important decision to make when considering a swap and can really affect overall engine operation. The cam the Viper engines come with isn't bad and changing it to another one won't give any big power boosts unless other changes are made as well.

I went with different heads altogether (with a complimentary cam) because I wanted more than ported o.e.m. heads could offer.

Hope this condensed version helps, but it is an extensive topic...

 

[ARRESTmeRed04]

ronnie what kind of numbers are you putting out?

 

[rottenronnie]

ronnie what kind of numbers are you putting out?

566 wheel/586 TQ

No headers
No cold air intake
No ported manifolds

 

[kyle's srt10]

566 wheel/586 TQ

No headers
No cold air intake
No ported manifolds

That's pretty stout for a QC isn't it:dontknow: That would be around 600rwhp in a RC right

 

[rottenronnie]

That's pretty stout for a QC isn't it:dontknow: That would be around 600rwhp in a RC right

Close, I would say. I went round and round with this before and I think there is a 30 'ish h.p. loss through the auto.
I am not a big dyno fan (which is why I don't list numbers in my sig) but two dynos told me the same thing; I will know better when the track opens.
The mods made an enormous difference however...The first victim was the auto, but it is fixed now and stronger.
More recent victims are guys I raced last year...a big difference there...

 

[Yellow venom]

566 wheel/586 TQ

No headers
No cold air intake
No ported manifolds

Hey Ron,more questions for ya! LOL! Why no headers or a CAI? Wouldn't they help you out?

 

[rottenronnie]

Hey Ron,more questions for ya! LOL! Why no headers or a CAI? Wouldn't they help you out?

At this point, it just doesn't feel like the engine is at all restricted. It pulls like a freakin' train.

Maybe at sea level it would appreciate headers and intake but I just can't see either of them making much of a difference. In fact, the K&N c.a.i. kit was my first mod (when the truck was new) and it took a step backwards in performance, so I ebayed it just as quick as I could.

The factory manifolds and air box just aren't all that bad. Even more proof now that the heads and cam put higher demands on both and so far, so good...

 

[Yellow venom]

566 wheel/586 TQ

No headers
No cold air intake
No ported manifolds

Hey Ron another question for you,LOL! Why aren't you using headers and a CAI? Wouldn't they help you out?
566 are some sweet #'s! :rock: :burnout: :rock: :burnout:

 

[ViperTruck2933]

To the original poster. Kyle is right. My truck (tommmy03's now) made 535 rwhp and 567 rwtrq with PBJ ported heads, custom grind cam and portmatched intake runners/TB, headers, CAI.

Those numbers DID NOT sacrifice low end torque. That is a misconception, because while it is TRUE that if you over cam for big hp numbers you WILL lose low end torque, MY CAM was ground for TORQUE. It was NOT ground for high hp. I could have posted much bigger HP numbers (and lower torque numbers) with my set up if I had wanted to go that way. My torque curve was high and almost flat across the top of the graph after my build.

My cam was also considerably bigger than a 708 cam. Unfortunately, to use the cam I used you NEED to do the heads and runners and you need headers and CAI. So you are not going to see my results with 2K.

As for how well the setup worked......well just ask the Paxton blown 630 rwhp 05 RC that couldn't keep up with me from a dig or a roll. :rock:

If you are serious about doing the cam swap, you need to talk to Joe at PBJ. He knows exactly how big you can go with your supporting mods without over sizing and he knows just how big to go to maximize your particular set up.

 

[rottenronnie]

To the original poster. Kyle is right. My truck (tommmy03's now) made 535 rwhp and 567 rwtrq with PBJ ported heads, custom grind cam and portmatched intake runners/TB, headers, CAI.

Those numbers DID NOT sacrifice low end torque. That is a misconception, because while it is TRUE that if you over cam for big hp numbers you WILL lose low end torque, MY CAM was ground for TORQUE. It was NOT ground for high hp. I could have posted much bigger HP numbers (and lower torque numbers) with my set up if I had wanted to go that way. My torque curve was high and almost flat across the top of the graph after my build.

My cam was also considerably bigger than a 708 cam. Unfortunately, to use the cam I used you NEED to do the heads and runners and you need headers and CAI. So you are not going to see my results with 2K.

As for how well the setup worked......well just ask the Paxton blown 630 rwhp 05 RC that couldn't keep up with me from a dig or a roll. :rock:

If you are serious about doing the cam swap, you need to talk to Joe at PBJ. He knows exactly how big you can go with your supporting mods without over sizing and he knows just how big to go to maximize your particular set up.

I didn't have to sacrifice low end either as my cam choice also provided a nice broad, reasonably flat torque curve; and is also bigger than a 708. I was simply trying to illustrate what can happen with the wrong cam choice.

As for NEEDING HEADERS AND A COLD AIR KIT, I'd have to call you on that one.

 

[ViperTruck2933]

I didn't have to sacrifice low end either as my cam choice also provided a nice broad, reasonably flat torque curve; and is also bigger than a 708. I was simply trying to illustrate what can happen with the wrong cam choice.

As for NEEDING HEADERS AND A COLD AIR KIT, I'd have to call you on that one.

We could argue the point all day and get no where. I think that you would make even better numbers with headers, CAI, portmatched intake runners, ported TB and CAI.

Did you look and see how much of a difference there is in the intake runners and the intake ports on your heads? :dontknow:

 

[ARRESTmeRed04]

tim, thanks for the input i wasn't talking about 2k total that was just for the cam and supporting valve train stuff to handle it, you wouldn't happen to have a dyno sheet laying around would you?? and ronnie man those are some awesome numbers man i can't wait to see what you run at the track. as for me tims setup sounds like a step in the right direction and then add a little laughing gas and shoot for 11's

 

[rottenronnie]

We could argue the point all day and get no where. I think that you would make even better numbers with headers, CAI, portmatched intake runners, ported TB and CAI.

Did you look and see how much of a difference there is in the intake runners and the intake ports on your heads? :dontknow:

I wasn't arguing; I was just trying to let some of the guys understand the pitfalls of swapping a cam in this or any other engine. Especially a BIG cam.
As I have no idea what their backgrounds are or just what each individual is trying to accomplish, I thought it would be generic and clear enough to help someone out. Perhaps not....

The rest was done with private emails.

There are an almost infinite variety of paths to take in engine development.

Yes, I looked at a lot of things while taking my engine apart and putting it all back together. I was particularly horrified at just how bad the burn patterns were on the piston tops and matching areas in the combustion chambers for a performance engine with flat top pistons.

I left the intake/head port mismatch intentionally to act as a reversion dam. It is perfectly fine to leave a mismatch as long as the mix is going into a larger port than a smaller one (that would be bad). Enlarging the intake ports in the manifold would slow the velocity (especially in a n.a. application) and at our altitude, not something I wanted to do. Am I trying to suggest that you shouldn't port match? No, not at all.

As for headers, I don't think it would be worse but looking at the numbers, there doesn't appear to be an exhaust restriction nor the need for more efficient scavenging.

The cold air intake doesn't appear to be a required item either. Same for a ported throttle body. Perhaps good items for you or many others that have installed them.

Some of these items are for bling, in my opinion, and I think right now I am at the cost vs. performance point of diminishing returns.

Rotten (learning as I go like the rest of us) Ronnie

 

[ViperTruck2933]

I hear ya. I was just speaking hypothetically that we could argue the points. Didn't mean to sound like I was accusing you of argueing. I applaud you for doing your research and your results are definitely impressive.


I think going too big with the cam is probably one of the most common mistakes in engine building.