Was at my engine builders shop to-day and saw the new design mechanical fuel pump by Harold Stewart for SB Chevy ( Stewart Waterpump founder) Very nice piece .... Big Block version coming soon, if it does what it says no need for electric pumps and all the plumbing .very impresive not to mention it looks really clean on the side of a motor. Alll kinds of applications .carb , FI and Nitous ... with the pressure and volume it pumps no need for any other pump

http://www.racepumps.com/tech.html

their mighty proud of it aint they, $280 :eek:

I will try the BB one when it comes out and report on it.

280.00 isnt expensive if you only have to buy ONE more fuel pump. I'd be very interested in this pump also. Anyone know how much HP a high volume mechanical pump uses???

I am on their email list when the BB version comes out

Cool, If it replaces noisy electric pump, and will feed a hungry rat's gas guzzling carb, and a shot of NO2 it would easily be worth the asking price. Looks trick as well! I will let others go first, looking forward to some "how it worked for me" reports!!!!!

Bob, they say this about that...

"RacePump also consumes less horsepower requireing only 25lbs of pushrod pressure compared to 125lbs(!) pressure of the brand"E" pump. "

So this one is much less than a standard hi volume mech pump.

It's interesting. I really don't understand how that pump will maintain a constant flow and pressure for fuel injection applications though.

Peter

If it works as advertised, it sure would make EFI swaps a lot easier. Still need a return line, but can eliminate the in tank or in line high pressure pump, along with the wiring. Almost sounds too good to be true.

It's interesting. I really don't understand how that pump will maintain a constant flow and pressure for fuel injection applications though.

Peter

Ditto!!

If the pump produces its pressure on the extension of the pushrod and it only takes 25# to push the rod in, how does it make more than 25# when it pushes out?

I don't see how the orings will be able to tolerate a million cycles using fuel as the lubricant.

Guys , I agree it looks too good to be true , I can tell you at least 2 circle track SB Chevies my builder has out there have it installed and one street motor with Nitrous/FI is being built at the shop with plans to install this pump so if any issues he will find them soon ....... this pump developed by Harold Stewart who as I understand it a pretty sharp engineer ..... supposedly wortked with Nascar owner Ray Everingham after he sold his water pump biz.

Well guys, I have one on order. I'll let you know how it does verses the mechanical I have now. When the motor is back in that is.
I'll make a couple runs with the current pump first and then install the new one.
Hopefully I'll get all the engine parts back from the machine shop by Friday.
Gary

If the pump produces its pressure on the extension of the pushrod and it only takes 25# to push the rod in, how does it make more than 25# when it pushes out?


It takes 25lbs/force to push the rod in, running off the cam lobe. This has nothing to do with outlet pressure. Pressure is resistance to flow, a smaller line will create more pressure for instance, but it's the regulator that resists output flow and creates the pressure.
As for constant flow, a piston pump creates a pulsating flow, same as a diapragm pump, which a stock type mechanical fuel pump is. Neither creates a constant flow, one reason why electric pumps are used.

i was looking into using one of those pumps, kinda hope someone tries one and posts results
aeromotive is coming out with a new one soon, its billet, 20lbs pres

the downside to the race pump is if it needs a rebuild, you have to send it back
the best bang for the buck if you need a mech pump is the carter 172 gph,
$70 from summit-i was going to try one of those, boost ref it and see what happens

That is still old pump technology with a new twist. There are many pumps on the market with that style of o ring design.

It takes 25lbs/force to push the rod in, running off the cam lobe. This has nothing to do with outlet pressure. Pressure is resistance to flow, a smaller line will create more pressure for instance, but it's the regulator that resists output flow and creates the pressure.
As for constant flow, a piston pump creates a pulsating flow, same as a diapragm pump, which a stock type mechanical fuel pump is. Neither creates a constant flow, one reason why electric pumps are used.

If I closed off the fuel line completely, would the pressure go infinitely high and blow up the line? What determines the upper limit of the fuel pressure? If the return spring exerts 25# of pressure on the shuttle, how does this translate to 60# at the outlet?

It depends on the piston area. Just take the force divided by the area. The drive rod has 25lbs of force, then with a piston area of 1 square inch it could make up to 25psi. (you'd have to subract friction losses and such) If the piston was only 1/2 sq in, then the pressure would be up to 50 psi.

I think the 60psi is controlled by the floating valve. If pressure builds up, the floating valve will be forced over to the inlet side (looking at running diagram), cutting off the supply of fuel until the pressure lowers. The valve has holes in it that are designed to do this at a prescribed pressure. Acts like a relief valve.
If you closed off the line completely, pressure would build to 60psi and hold there until it is allowed to escape.
How long do you think those o-rings will last? What about using with alcohol? And if the o-rings go, will fuel leak into the oil pan?
Chris.

Anyone hear of anything additional on this pump?

Thanks,

Bump.

All the SB guys that Ii know that have one are pleased ....Stewart only made 50BB ones and they are all sold and he monitoring the performance in case they need some further mods ( heat issue) expects to make a major run of more BB ones in 3 months ..... he was surprised at demand for BB ones

I am interested in the BBC version for two reasons.

First, next to the Carter 172, its the only mech pump that will be enough for my 454.

Second, its the only pump that will fit in the limited space I have to work with on my little Z car. So, I can't run the Carter (or any other pump) anyway.

Any idea what the cost will be for the BBC version?