fuel pressure

A friend of mine has a 704 tall deck chevy in a boat with a 1471ssi with a 1100 fuel pump.He has a 80 in the pump loop,110 in the high speed,and around a 100 main.His fule pressure goes over 200 psi on launch and stays over 180 the whole pass.I think this is way to much fuel egt's are at 800-900 but,he wanted me to get ya'lls opinion.He has blown this thing up allot and I am just trying to help him out.My fuel pressure stays aruond 80 psi and works just fine.Thanks for any help.

 

that is about the same pressure that we run...read the plugs and rod bearings..Dave
www.myspace.com/daveloweswr

 

This is where wedge/splayed motors and hemi's part ways. I found this out from a friend of mine who's done alot of flow work on wedge motors. I was always a firm believer in maxing out the fuel pressure. Higher pressure means better atomization which means more power. But, when it comes to wedge and splayed valve motors, lower fuel pressure is better. Because of the turbulent air inside the chamber of a Chevy, the higher fuel pressure will have a tendancy to tumble and bounce off the chamber walls. Then you get fuel droplets that fall out of suspension. Lower pressure will just flow right into the chamber and burn better. Picture yourself inside a hemi chamber. It's like being in a wind tunnel where the wind blows in one side and out the other. Now, picture yourself inside a Chevy chamber. You have wind blowing from all directions trying to blow you all over the place. For all you east coast people, we call that Santa Ana winds. I didn't believe this at first until I tried it. The motor liked it.

 

I run low pressure also.....wedge motor, SBC. 6.60's 203 8% over 8-71 393 inches.

 

fuel system tuning

pressures exceeding 200 psi will damage or atleast severely shorten the life of the pump! A good opperating range is between 125 and 175 psi max. I would start with slightly larger hat nozzles and increase the pump loop a tad also. The altimate goal being to keep the system pressure down a bit and too keep the main jet sized around .080 . Don't forget when you do this and the system pressure runs lower, the high speed will need less opening pressure to react at the same time and a little smaller jet to move the same volume of fuel at less operating pressure. good luck! Dont forget to start with an 080 main with these changes !

 

Which head gets better gas milage or bsfc? cant has better squish hemi has better flow.

 

From what I've seen the chevy conventional style head (Dart 360) has a much better BSFC than for instance a Brad-4, but it won't make more power

 

I like my fuel pressure to be in the 145 to 150 range; if you are running higher than that, make sure your pump saver valve is set up so it won't open during the run, especially if you plumbed it back to the tank or to the fuel pump inlet. If you plumb it into the back of the hat, a leaky pump saver valve will just go back into the motor and shouldn't hurt anything.