RB install questions

[nickgarthright]

Hello, I have a 1978 280z that I was planning on doing an RB20det swap in. Can you use the original 280z fuel pump because it's fuel injection? I'm trying to keep the cost down so I can spend money in other areas of the car just in case you were wondering why I'm asking this.

 

Thanks!

[pat1]

It will run with the 280z stock pump but I wouldn't suggest it. It's not going to supply enough fuel. Get a Walbro inline pump. You can get one for 130.00

Edited January 14, 2015 by pat1

[mtnickel]

Here's another member who had some to say on the capabilities of the stock pump.

 

http://forums.hybridz.org/topic/76319-bosch-910-fuel-pump/?p=726454

 

"33 gallons per hour at 38psig and 12.85v" with stock pump"..."which is enough for about 270rwhp"

 

That 270whp is likely very very optimistic.

Note:

1) You'd probably want a reasonable safety margin for slight voltage dips, temperature fluctuations, etc. So figure 10% less. = ~245whp.

2) If you're on stock wiring, your pump may not see 12.85. Could be much lower. Lower voltages can drastically affect the flow rate of the pump

3) that measure above is at a static 38psig. Figuring you will run at least 10psi of boost, the pump will need to run at more like 48-50psig. (Remember the Fuel pressure regulator references the manifold pressure). The higher pressure the pump has to work at, again, the less it will flow.

Add all that up, and I would probably only feel safe running 200whp. But given it's age it's a tossup.

 

Back to the short answer "it would run, but I wouldn't suggest it" (I assume pat meant "wouldn't" above).

 

Good luck with the build and welcome to the RB Z world!

Edited January 14, 2015 by mtnickel

[puretone]

Hello, I have a 1978 280z that I was planning on doing an RB20det swap in. Can you use the original 280z fuel pump because it's fuel injection? I'm trying to keep the cost down so I can spend money in other areas of the car just in case you were wondering why I'm asking this.

 

Thanks!

 

Here's another way of looking at it:

 

That pump you are using, the original 280Z pump, is most likely VERY old and VERY tired. Whatever its specs were when it left the factory, rest assured that it is nowhere near capable of providing that kind of flow or pressure it was designed to output initially. 

You can do some seriously bad things to, what I will assume is currently the highest dollar item in your car, your engine by starving it of fuel. Same holds true for oil starvation of course. From what I gather over the years, having spent waaaaaaaayyy too much time cruising car / car engine forums is that literally nobody gives even 1/2 of a single f##k about fuel pumps. Flabbergasting to me, really.

100-200$ gets you a fuel pump that will more than delivery the results you critically need. Pennies compared to engine damage from fuel starvation.

Invest into a Walbro (or similar trusted brand) 190-255lph pump and a fuel pressure regulator. The regulator doesn't need to be made of myrrh or anything, but at the very *least* get something that is adjustable and has some means of monitoring the pressure it flows.

Bonus: you *will* beyond a shadow of a doubt be able to rule out fuel pressure and/or fuel flow rates as gremlins when you do have some other shenanigans going on under the hood. 

 

You really can not come up with one good reason why you should keep an ancient fuel pump around. When you go in for a heart transplant, you don't settle for the 75 year old's recent donation over the young and crispy 21 year old's relatively new heart.