nitrous with tight lope sep

[lc-gtr-1969]

Apologies for reviving this old thread...

I just thought it might be of interest to this conversation.

My setup is running a cam with 266@50 thou duration on 100LSA cam, and successfully runs nitrous. I know its not ideal, and cylinder pressure was an issue- it needed copper head gasket and o-rings to keep the pressure in, but now that is sorted its all good.

ideally the same duration on 110LSA would probably produce a better curve etc on the bottle, with less peak cylinder PSI and therefore less risk to damage, but im just replying back here to say it can be done- whether its a smart move or not is another conversation.

[miniv8]

We went from 106 lobe to a 113 lobe on a small sbc nitrous application, and lost performance throughout. The intake manifold cleaned up though.

[Monza355]

We went from 106 lobe to a 113 lobe on a small sbc nitrous application, and lost performance throughout. The intake manifold cleaned up though.

I find that very interesting. Do you mind sharing some details about your combo ?

[miniv8]

combo was 7500rpm 355ci sbc, running 210cc Profilers and a Victor Jr. 200-250 shot of nitrous through a plate system depending on conditions.
Car lost the 60.foot and ran out of breath at the top end with the cam change. Near identical cams except for the lobe.

Well the 106 was a Competition Cam and the 113 was a Howard...

Our guess was, that unless you are running the way bigger jets, the wider lobe will hurt power.
I would suggest the wider lobe for making the engine live under the abuse of large doses of nitrous, not for adding power on sportsman nitrous cars.

Your results may vary.

[bigjoe1]

I did a situation sort of like that many years ago-- Just retard the cam by 8 degrees and it worked out VERY WELL


JOE SHERMAN RACING

[miniv8]

Thanks Joe, I'm willing to try that.

[Truckedup]

I did a situation sort of like that many years ago-- Just retard the cam by 8 degrees and it worked out VERY WELL


JOE SHERMAN RACING

I'll be running nitrous on one of my vintage 40 cubic inch Triumph LSR bikes...It's OHV with a separate intake and exhaust gear driven cams....Cams are usually set up with about 103-106 LSA for gasoline.....Retard both cams or just the exhaust?

[GARY C]

combo was 7500rpm 355ci sbc, running 210cc Profilers and a Victor Jr. 200-250 shot of nitrous through a plate system depending on conditions.
Car lost the 60.foot and ran out of breath at the top end with the cam change. Near identical cams except for the lobe.

Well the 106 was a Competition Cam and the 113 was a Howard...

Our guess was, that unless you are running the way bigger jets, the wider lobe will hurt power.
I would suggest the wider lobe for making the engine live under the abuse of large doses of nitrous, not for adding power on sportsman nitrous cars.

Your results may vary.

How much did you change duration and intake center line? My understanding on a nitrous specific cam is that the intake lobe stays the same and on the same center line, the exhaust close stays the same there for your overlap does not change, the only difference is exhaust opening and added duration to start the blow-down sooner. This will still hurt tq and 60ft times if the cam is retarded as well then it hurt 60ft times even more, add extra duration on top of that it hurts it even more so you have to dbl the amount of nitrous to gain anything.

I have a friend that runs a leaf spring drag radial car and progressive timer with a 400 sbc on a 106LSA with a class limited .076 pill he runs 5.60 eighth mile and in testing they ran as much as a .102 pill and a 5.30... It seems with nitrous when it comes to fine tuning cam specs you would need to get on the dyno with a plethora of cams and small changes in profiles to balance the loss of tq from the wider LSA and the gain you get from nitrous.