Spraying An LS3 Based 427
Oh sorry, forgot about the heads thing. Well anyway, the stock L92 heads don't flow as well on the exhaust side compared with some aftermarket heads or worked over stock heads when n2o is considered. Though they are still a good head overall, but not the best sprayed head. So, if your having work done to them, the exhaust side really needs some attention, and your porter should know that your spraying and address the exhaust flow. You can also get a cam spec'ed for these heads that will wake up the exhaust side in comparison to the already good flowing intake side, we want some added duration as well as some added lift. The reason the exhaust side is so important is the fact that spraying increases the exhaust volume but not the intake volume. Here's why, when we are spraying any given size shot we displace air with any added spray volume so as to end up with the same overall intake volume. Then when the spray/air mix gets into the combustion chamber and the added oxygen in the n2o is released at a certain temp, and the added gasoline for this oxy combusts, we now have a greater exhaust volume and thus the reason we need to address the exhaust side all the way to the tail pipe IE: heads, headers, 3" exhaust, no cats... Now with all that said, if spraying only a small shot, the stock L92 heads will be fine out of the box, but who ever stays small with nitrous, lol. What happens with stock heads and/or poor flowing exhaust side going with bigger spray is heat issues. If we can't get a free flowing exhaust system put together and go big, the heat build up can be ginormous and we all know heat equals detonation, and detonation can equal destruction, ask me how I know, lol. Hope this made a little sense, lol, as i kind of jumped around a bit. 
Robert
Robert
Oh sorry, forgot about the heads thing. Well anyway, the stock L92 heads don't flow as well on the exhaust side compared with some aftermarket heads or worked over stock heads when n2o is considered. Though they are still a good head overall, but not the best sprayed head. So, if your having work done to them, the exhaust side really needs some attention, and your porter should know that your spraying and address the exhaust flow. You can also get a cam spec'ed for these heads that will wake up the exhaust side in comparison to the already good flowing intake side, we want some added duration as well as some added lift. The reason the exhaust side is so important is the fact that spraying increases the exhaust volume but not the intake volume. Here's why, when we are spraying any given size shot we displace air with any added spray volume so as to end up with the same overall intake volume. Then when the spray/air mix gets into the combustion chamber and the added oxygen in the n2o is released at a certain temp, and the added gasoline for this oxy combusts, we now have a greater exhaust volume and thus the reason we need to address the exhaust side all the way to the tail pipe IE: heads, headers, 3" exhaust, no cats... Now with all that said, if spraying only a small shot, the stock L92 heads will be fine out of the box, but who ever stays small with nitrous, lol. What happens with stock heads and/or poor flowing exhaust side going with bigger spray is heat issues. If we can't get a free flowing exhaust system put together and go big, the heat build up can be ginormous and we all know heat equals detonation, and detonation can equal destruction, ask me how I know, lol. Hope this made a little sense, lol, as i kind of jumped around a bit.
Robert
Robert
This is probably a stupid question but is there any way to get a bigger exhaust valve in the L92 head?
Not sure on the increase in valve size, but I would think so. really, just a little port work and they flow well; even if you have no work done, unless your going real big, a good cam can do wonders, talk to Pat G, he's our site cam guru.
Robert
Robert
