Nitrous cams...farce?

[Freiburger]

I don't believe in "nitrous cams." How about you? In my experience, you build the most power you can get on motor, then stack nitrous on top of that. I have not seen a case where a "nitrous optimized cam" that makes less power on motor then makes more power on nitrous. Then again, my experience is limited to 275hp shots and less, which could be the issue.

What are your thoughts?

[Scott Liggett]

Re: Nitrous cams...farce?

From what I've read about Nitrous or Blower cams in the catalogs is they have a wider lobe separation. They have 114 degree separation instead of the non Nitrous cam's 108. Also, they open the exhaust valve earlier to help completely scavenge the cylinder during the exhaust stroke. Supposedly, the wider angle helps keep cylinder pressure up and not lose it through the exhaust valve. The exhaust valve opening earlier supposedly completely empties the cylinder in order not to contaminate the incoming air/ fuel charge. According to Comp Cams, this builds power.

Sounds like your first comparo article in the making.

[TheSilverBuick]

Re: Nitrous cams...farce?

Along those lines with a wide LSA I thought they were designed to help prevent an intake backfire. I've never used Nitrous nor really ever intent to, so superficially that's what I thought.

[JustinSuhas]

Re: Nitrous cams...farce?

I've never used Nitrous nor really ever intent to

? you don't like nitrous?

[Eric68]

Re: Nitrous cams...farce?

I don't believe in "nitrous cams." How about you? In my experience, you build the most power you can get on motor, then stack nitrous on top of that. I have not seen a case where a "nitrous optimized cam" that makes less power on motor then makes more power on nitrous. Then again, my experience is limited to 275hp shots and less, which could be the issue.

What are your thoughts?

That is an interesting thought and one that I've wondered myself.

The wide LSA and long exhaust duration open the exhaust valve early so blow-down starts earlier, but in the process you waste pressure out the exhaust too.

Personally, I subscribe to David Visard's position that the best way to maximize performance on the bottle is to have a head with a killer exhaust port and keep exhaust duration more "normal."

Didn't HRM do a N2O cam dyno flog a while back that didn't really show any improvement?

PS. My opinion is that N2O cams are often a crutch for a non-optimized exhaust port.

[VWMMP]

Re: Nitrous cams...farce?

There was talk about this at www.speedtalk.com last year. IIRC the reason to open the exhaust a little earlier was to cut down the on the pressure spike and heat before they got out of hand. The reason for the longer duration was to make sure to scavange the cylinder completely, just to make sure you did not get a build up of nitrous. These were discussions regarding 300-500 hit systems on a big block. One person mentioned that the amounts of change needed slowly increased depending on the amount of spray.

One builder mentioned that his motors are designed quite a bit differently when running nitrous. So much so that they are down on power versus a similar setup not designed for nitrous.

[ethelkilledfred]

Re: Nitrous cams...farce?

When we run a nitrous cam, it has more duration and wider lobe centers to take advantage of nitrous. We over cam it. Usually a smaller cam will go faster in the motor. We treat the motor as if it was bigger, due to the power we can generate with nitrous. So a 468, we threat it like a 540 or a 633 depending on how big a shot we put in it.

[TheSilverBuick]

Re: Nitrous cams...farce?

I've never used Nitrous nor really ever intent to

? you don't like nitrous?

I don't like the idea of having to fill two tanks to make power, gasoline is enough. Besides I'm a high altitude resident, I'll go for a supercharger or turbo first.

[min301]

Re: Nitrous cams...farce?

I don't believe in "nitrous cams." How about you? In my experience, you build the most power you can get on motor, then stack nitrous on top of that. I have not seen a case where a "nitrous optimized cam" that makes less power on motor then makes more power on nitrous. Then again, my experience is limited to 275hp shots and less, which could be the issue.

What are your thoughts?

That is an interesting thought and one that I've wondered myself.

The wide LSA and long exhaust duration open the exhaust valve early so blow-down starts earlier, but in the process you waste pressure out the exhaust too.

Personally, I subscribe to David Visard's position that the best way to maximize performance on the bottle is to have a head with a killer exhaust port and keep exhaust duration more "normal."

Didn't HRM do a N2O cam dyno flog a while back that didn't really show any improvement?

PS. My opinion is that N2O cams are often a crutch for a non-optimized exhaust port.

This has long since been my opinion.

[JustinSuhas]

Re: Nitrous cams...farce?

i know what you mean about altitude. my father lives in denver, his mustang is supercharged and his jeep soon will be ;). however, being a poor college student, nitrous is my most affordable power adder.

[ethelkilledfred]

Re: Nitrous cams...farce?

I've never used Nitrous nor really ever intent to

? you don't like nitrous?

I don't like the idea of having to fill two tanks to make power, gasoline is enough. Besides I'm a high altitude resident, I'll go for a supercharger or turbo first.

We had a lot of guys tell us the same thing at the track, but when they saw the results we were having and knowing we were on a tight budget, they started trying it out for themselves and found out that going fast is still going fast, no matter how you do it, turbo, blower, nitrous or N/A. Our 7.80 pass brought the place down that night. Everyone was having trouble getting down the track that night. This is a track where 12 second cars were getting loose and crashing. We laid down the 7 second pass skating down the 1320, it was quite memorable.

[TheSilverBuick]

Re: Nitrous cams...farce?

Oh, I am not against it's use, it's just not for me. I don't have to be the fastest, just fast enough to keep my mild ego satisfied 8) Not to say 20 years from now I'll be eating these words and going all out ;D

Yeah, I'm another 1000' above Denver too.

[JeffMcKC]

Re: Nitrous cams...farce?

Its seems there is two schools on this, the killer motor little shot, or stout motor huge shot.

If you build a killer N/A motor it wont take the huge shot, pistons are to light, runners to small headers are to small. The head volume and intake need to be bigger headers are bigger. The gas takes up space.

There is more power made with the spray, so if you are going to kill it with 800 plus hp of spray ( there are guys with 5 systems) you got to have a custom piston ( look at BRC ED Wilson pistons) ,ring stack, rings, exhaust valves and cam and springs to take the hit, plus a real tight converter to not blow right threw it. Its is unbeliveable how much guys are throwing at the engine right now.

I have been looking into this a lot : and it seems 250 is the cut off, after that your tune better be right on if your going to use non- spray built stuff.

[VWMMP]

Re: Nitrous cams...farce?

Off topic for a minute - Jeff I see in your signature "Thanks RFD...." Did Curtis port your heads?

[KeithTurk]

Re: Nitrous cams...farce?

Jeff I believe Freiburger would still build a standard Nitrous Motor... he would simply optimize the combination naturally aspirated before he started sorting out the Nitrous side... Ultimately allowing the N/A side to dictate the came rather then the Nitrous "grind"...

To run Nitrous successfully you still have to have the thick pistons... rings down in the bore... ring gap's and so on...

The only thing I'd like to add to the comments... is on the Nitrous cam side... you can open the exhaust sooner simply because what's in the chamber past half stroke is junk... totally spent..... all bang, no push....

Keith ( and yeah we've run a bunch of motors on the bottle successfully with both cam styles... though today I'd do it David's way )