Hp500efi rebuild
 

I recently bought a hp500efi and looking to build a 650 hp 540ci out of it. I'm curious what other guys are running. Retuning the efi system, carb, or installing aftermarket efi system such as holley. As always I appreciate all the help I can get.

Stock EFI intake hits a wall around 600-620hp

These 540's made 630hp, thats all the intake will support

https://cimg2.ibsrv.net/gimg/www.off...0c928d25fd.jpg

I'm assuming bigger injectors? Any idea what I would need to use if I decide to use the efi

This can be done for 13K, looks like more power available with added services.


https://cimg4.ibsrv.net/gimg/www.off...9ffc5a0ae1.png

65 lb hour injectors, stock TB and intake runners, custom grind double swap cam and AFR heads

a 525 style flame arrestor with a monoblade tb properly tuned will help a built 500 gain about 15 to 20 hp on top and more peak torque. The FA's are super expensive at 765$ each though. You CAN buy the 525 throttle blades for 50$ to bore out IF you know a competent machinist . hardin or somone sells a 525 fa for 600$

Did you have the FA's on when you dynoed? I saw a restriction from them at less hp on my dyno

yes, full dressed with CMI sweepers, maybe we should of taken them off and do a pull, but we didnt

I honestly thought someone would have suggested selling the HP 500 and just buying a 540 as opposed to conversion.

A lot less work and prob cost less in the long run too.

https://www.ebay.com/itm/MerCruiser-...QAAOSwjL5ZFdX3

https://www.ebay.com/itm/540-Bulldog...IAAOSwnK9ZVqxK

https://cleveland.craigslist.org/bpd...145891904.html

Just curious, what did you buy the 500 HP for? I've got a 502 MAG (black engine) that I would ultimately like to upgrade and a 500 HP EFI would be what I'd want or replicate for reliability.