With the cast pistons I wouldnt go more than a 100HP hit.Make certain your furl and ignition are up to the task as well...One lean out at WOT and its by by pistons...
Good and timely question. My brother bought me a NOS setup for Christmas, but FedEx hasn't delivered it yet, so I have no ide what it is. I am up at 3am wondering how much I can throw at my engine without scattering parts all over....
I have sprayed 150 horse shots on "stock" engines with no adverse affects. BUT they were tuned to the max and had adequate fuel supply. That is where most mess up, They lean out on fuel then "N20 blew up my motor". Where they really burnt up their motor. I have saw this scenario many times in the past years. I cant stress enough about the fuel supply,And just because you show pressure doesn't mean you have the volume.Timing is next, Be sure where your timing is at. Verify TDC, don't take the balancers word for it verify it for yourself. 28 degrees total is a very good place to start, Yes you will give up a little power but it will be safe. Read the PLUGS after every pass. If somthing is wrong the plugs is the first to show the signs.If you will treat NITROUS with a LOT of respect you can get away with using it without any damage. But dis respect and it will slap you in the face hard.One other thing, Nitrous for racing is nasty, I'm sure its due to the handling, Filling process. But it would amaze you at some of the stuff i find in my filters. I have never used Teflon tape on my nitrous stuff and my filters will be full of it. USE MORE THAN ONE filter. And be sure to use one at the solenoid entrance. I prefer the screen wire ones here. You don't want a hung N20 solenoid.
So, would it be safe to just disconnect the vacuum advance on race night? Mine runs up near 50 degrees with vacuum on. Which, based on your description, is WAY too much. Car runs fine on it, but it doesn't sound like nitrous would like it.
You need to recurve your distributor. 38 degrees tops. Disconnecting the vacuum advance is a no no. Nitrous and timing has to be on the money or it will go BANG
If the vacuum advance is off, it is 10 degrees at idle, 40 full on. So if I backed it off a couple degrees at idle and kept the vacuum off, it would be right at 38. That is why I asked.
But it LIKES 50 degrees. Dynoes with and without and it ran better with the vacuum on and running 50 degrees. Actually, (Sorry for hijacking the thread) I am in the market for a better distributor, and not just this pertronix-in-a-stock jobby. I need something I can tune, and not just live with what it gives me.
Sorry about hijacking this thread also. If you want the engine to last any time at all then tune it to be dependable...not tuned for max hp. Why do you think the big boys rebuild engines in the pits between each run? They are looking for maxuim power at all cost. How offten do you drive at WOT? If you're building a racecar that will be pushed on a trailer is one thing but if you drive it on the street is another. You can't have your cake and eat it too.
Actually, I don't drive the car much, and when I do, I am often at WOT. But I know what you are saying, and I know I have been in need of a better dizzy for a while. Actually trying to get one off another member as we speak.
I am glad the question got answered in the first few posts before I got it all hi-jacked...:sorry: On the bright side, though, if he is planning on spraying his engine, he probably needs this dizzy info as much as I do.
When looking at your advance it is not unusual to see 50 degrees with the vacuum connected. With the vacuum disconnected a Ford small block with stock configuration heads should have around 34 degrees maximum. When you are at WOT there is not enough vacuum to advance the timing with the vacuum advance - that is why it is not counted in the max advance for power equation. That is also why it is simply disconnected when checking total advance and then reconnected to run.
