I don't know an answer to that question. Port injection is going to have some advantages but I don't know if you can really feel the difference on a street car.

That looks like a pretty clean install.

One thing that favors EFI is the lack of anti-vapor lock additives in new fuels.
Since the whole system is under high pressure until it’s discharged by the injectors, less weird fuel related hot weather issues to deal with.

There is still heat related issues, most of which is getting the whole load of fuel hot on long drives. Using a 600HP fuel pump to cruise around town causes lots of return from the hot fuel rails. The drag week people fight it the most, you see fuel coolers, ice packed fuel cells, etc on hot days.

I asked my question because of the additional pieces involved with going MPI - fuel rails/injectors, controllers etc. Guessing any noticeable difference would probably be more related to finite tuning ability of MPI vs throttle body.

However, it seems like you could save yourself some headaches by not going to individual injectors. Point being if the Sniper provides decent enough results then there is probably less reason to choose MPI.

I guess I was “assuming” the sniper type throttle body systems were dead head from the pump to the throttle body........ no return....... which would help curtail the hot fuel issue bad340 is talking about.

I’m likely assuming this incorrectly though...... I do see two lines in the upper left corner of Andy’s last pic.

Fuel system:
All efi fuel systems should be a return type.

TBI vs mpi
Multiport helps with cold start because the manifold is dry. It also eliminates distribution issues. Allows individual cylinder adjustments. Gains hood clearance because MPI TBs are shorter. Almost required for high boost applications. But in most cases there is very little difference in a street car.

Andy does the flat hood on your 65 work with your trick flow intake?

Yes, the flat hood works just fine with the Trick Flow intake. No problems closing the hood. Plenty of clearance for the air cleaner as you can see.

Looks like it almost works. Lol how thick is the filter?

Andy, what fuel pump did you use with this system? Holley now offers direct fit fuel tank kits (made by Tanks, Inc.) that come with a Walbro (I think) 255 lph drop in pump. They claim the 255 pump will support up to 550 hp. I know you are making more steam than that. They have a 400 lph pump as well. Did you use something like this or did you go another route?

Holley/Tanks Inc. '68-'70 B body EFI tank kit

Holley 400 lph fuel pump

I used the Aeromotive Phantom pump which is only 200 lph. 200 lph is 53 gph or 318 lbs/hour which is enough fuel for more than 600 hp.

The important thing is the flow rating at 60 psi. For a 600 hp engine you need 50 gallons per hour at 60 psi.

I'll have to see how the pump does on the chassis dyno. On the street it holds pressure just fine even at WOT on the freeway. The 400 lph pump would also work in my car but would be overkill.

If the 255 pump will put out 255 lph at 60 psi then it is good for 800 hp. I wouldn't have any problem using one of those in a hot street car.

Holley doesn't list specs on the pump so you have to go to the Tanks Inc website. Tanks Inc does an excellent job listing specs and even shows a flow vs. pressure chart with different voltage and amp draws.

The GPA-4 which is the 255 lph pump will deliver 65 gph at 60 psi if the alternator is working (13.5 volt system).

65 gph is 390 lbs/hour which is enough fuel for 800 hp. So I don't see any reason to use anything bigger than the 255 lph pump for the normal Mopar stroker engine. You would need to be running a monster of an engine on the street to need the 400 lph pump.

I run a Racetronix 255lph, no issues with fuel pressure, system runs at 58psi. I can control PWM and slow it down at idle and cruise, but fuel still heats up. Not enough to cause issues though.

Even ran the 255 when my car was carb'd regulated down to 6psi.

This is a little off topic...who's valve covers are those Andy?Very clean look. Also, any decision on the water neck/sending unit piece?Would like one for sure.

Good info on the fuel pumps, thanks. It's easy to get sucked in to thinking you need more flow capability.

Looking at the GPA-4 flow chart, the difference in pressure between 12V and 13.5V is something to consider though. Like you said Andy the alternator needs to be doing it's job.

I actually run 2 Walboro 255LPH Pumps. One runs all the time and the other comes on over 3500RPM if throttle is greater than 70%. At maybe 600HP I can live on one pump but the extra doesn't hurt. It has also come in handy when I had a pump die on the road, I just moved my fuel pump relay wire and I was back in business in less than a minute.

Same here, 2 pumps in the cell, one 340LPH that I switch to when I spray it. Having a spare was the main driver though.

I made the valve covers. Just start with a big chunk of aluminum and whittle away at it until it looks like a valve cover!

I'm going to get more of the water neck spacers built. I sent a CAD file out for quotes so I should have parts on my website in a few weeks.

Yep, having a good alternator really helps. If you look at flow vs. amps you'll see that running the system at 13.5 volts increases pump flow significantly but doesn't require much more current.

The new stuff with PWM really helps. The Sniper can't deal with PWM (as far as I know) but the higher end EFI systems can control the pump in a smart way. That way you don't need to have the pump on full bore all the time.