650 or 750 hp

[jaspermaggie]

I al looking to get a new street hp dp 650 or 750. I have had 670 avenger and a 750 vac. The 670 felt better but never took it to the track to see.

Chevy 355, rpm airgap, trickflow 195, 10.3 to 1, 1.5 rockers, 284 228/232 480/494 110, full header no cat 2.5 supper 44 h pipe, th350 3000 3.70 27" radial. I also have 125 nitrous. Car is 3500 run 6400 rpm.

I think the car might be fine with a 650 but I know the 750 will make more power. My concern is the car is 3500lb

[BracketNova]

I am no expert, but I would say if you want to spin 6400rpm you should prob go with the 750. It might be a little more responsive with the 650 though.

TCI has a neat calculator here:
http://tciauto.com/Products/TechInfo/Calculators.asp#13

just my .02

[supernova]

750 V !!!!!!!!!

[jaspermaggie]

nova you think stay with the 750 vac? It would save me money. Would you say jet the 750v like the 750dp? What do you think of fuel line? I have a mallory 140 that has a -10 feed -8 to 2 regs the carb reg has -6 to carb and nitrous reg has a -6. Should I use a -8 to carb?

[supernova]

I ran a 780 vac on a 355 years ago but I had more cam, it worked great. The key for useing the 750 vac will be tunning it. Since you have a good converter and gear I would think about putting a 750 d/p on it. I ran a 750 d/p on a 385 sb with the same heads you have for years. I think tunning the 750 vac will help it run better over the 670. Your fuel system will be ok.

I know of a great solid cam that works well with your heads!!!

[BracketNova]

I was told to stick with the -6 to my carb. I thought bigger was better and was going to go
-8 but was talked out of it. It was explained to me that it is easier to keep pressure in a -6 than -8, I had forgot about the laws of physics.

[supernova]

I was told to stick with the -6 to my carb. I thought bigger was better and was going to go
-8 but was talked out of it. It was explained to me that it is easier to keep pressure in a -6 than -8, I had forgot about the laws of physics.

The rule is if you go over 700 hp you should use a #8 line, a #6 line for under 700hp. If your like me and make over 700hp you have to make sure the fuel pump is big enough to supply fuel for the hp range. In other words fuel consumption is the key to know what fuel line to use.
I run a #12 from the tank to the pump, a #10 from the pump to the fuel log, a #8 from the fuel log to the carb (both front and back bowls) , and a #6 from the fuel log to the nitrous fuel solenoid.

Pressure isn't hard to keep with the right pump but as HP rises the consumption rises also. Now you need volume at pressure. It takes more volume in a #8 line at pressure than a #6 at the same pressure.

Bottom line, the more hp the more fuel it will use!!!


Having approx. 1100 hp PRICELESS!!!!!!!!!!!!!!