Has anyone did back to back testing with the exhaust crossover blocked and not blocked? I pulled the intake off my engine and the crossover was not blocked,maybe thats why I had trouble in hot weather,the longer it sat,the quicker it ran,or the colder the air the better it ran. I had 4 tenths variance between cold and hot air. I didnt have a lifter valley splash pan either or windage tray in the oil pan,heck I might have got another tenth out of this combo. Both problems will be fixed with the new motor graemlins/thumbsup.gif

I have not done any testing. Generally, on a street motor, the exhaust crossover improves cold weather driveability by warming the carb to help prevent icing in the carb. A race engine doesn't need this and would probably be best if the crossover was blocked or eliminated.

I didnt think the Performer RPM had the crossover under the plenum,but it sure enough does. I have to think it hurt me a little bit,especially in the shoe polish race :D

not sure it would help surpass your best ET, but it probably would've been alot more consistant in hotter weather.

i went thru the whole ordeal with cooling my carb down for my z28 bbc 414. during test and tune there was a decrease in performance when the car was ran back to back on runs which isnt to good for bracket racing. specially when it comes down to the final few runs and there is less time for the engine to cool between rounds.im already running a cold air induction assy. that is sealed just to recieve outside air via my factory cold air hood scoop.

i took my intake off and added a splash shield under the rpm intake.(i already have a windage tray in the bottom) cut some block off plates out of a pop can for the heat cross over. and i wrapped every last inch of my fuel line with insulating padding from the time it enters the engine compartment to the carb. and i also rerouted the fuel line farther away from heat sources...like the block.

all in all i reduce some areas of the intake about 50 degrees (that being fully warmed up) specially the area were the cross over are blocked. there wasnt much change at the ends of the intake (runners like #1 or #2). the carb bowls lost about 25 degrees in heat because i think the fuel wasnt getting warmed up anymore going to the carb.

the end result made the car more consistant between rounds.

i have a thermo gun that i took readings from different parts of the engine and was able to notice the drops in areas from what i did.

i also use the thermo gun to determine when its time to go to the staging lanes to run and keep track of engine temps.