Return for a ka24de swap

[bertvorgon]

Does fuel starvation happen in corners or going straight?

We had that problem back in the 80's, as the pickup was on one side of the tank. We made a "well" or "sump"
that always ensures fuel available. I think the injection guys all have some sort of surge tank. Others that are injected can chime in on that.

[icehouse]

I’m less concerned with the gas smell and more concerned with functionality, so I guess I can tackle that later. Ha.

Everywhere I’ve looked, it looks like people just run a high-pressure in-line fuel pump for the swap. I haven’t seen discussion of any other option really. What did you do? Or suggestions on how to keep this simple?

Ps…
Fuel starve issue at 5/8 or 1/8 of a tank?

5/8 of a tank. Super annoying. But it's the simplest way. You can weld in a 90's car in tank flange and go that route. I've used the 240sx in tank setup. It was okay still not the best at autox. My coupe has the Z31 in tank setup. My buddy Rich built it for me. Next time I'm going to try Keith's version of a sump. Looks super simple. In my Z I built a maze type internal surge tank. It seems to work. Honestly no easy way to make a kick ass 510.

[James]

I thought all 510's were kick ass inherently?

[mhinkens]

Again, I apologize for asking questions that I eventually find the answer for online. I swear, been reading all the forums and doing lots of googling, ha. But that welded reservoir sent me on the right path to discovering that this is a super common issue with carbureted cars with old tanks. Sounds like you just set up a surge tank.

This is an old diagram, but this stuff is all over the web. Seems like this might be an easy solution.

http://www.sdsefi.com/techsurge.htm

[icehouse]

I thought all 510's were kick ass inherently?

kick ass looking. It's funny to dial in a car for a long time, then get a project 510 and take it for the first test ride. All I can think is "wow this is a long ways off from being a fun rig." haha.

[icehouse]

Under our racecar is a surge tank setup. We call it the meth lab haha.

[mhinkens]

Awesome. That’s actually a very simple solution in my eyes. Way better than cutting a hole in the gas tank. Ha. May I ask which fuel pump you’re using on the low pressure side? I have a decent walbro one that I was going to use to put into the injector system, but I’m gonna need to buy a low pressure one for the surge tank.

[icehouse]

funny you ask that. We had a original 240z pump for a few years until we raced Portland and it decided to die. We tried a few different pumps and they all failed including a high dollar I think Holley pump. It said in the instructions "don't run it dry" which is basically what our racecar does every tank. It lasted I Think 6 hours. funny thing is it will do gravity for about 1/2 the tank just fine. All the cheap pumps were even worse then they Holley. We then bought a Nismo low pressure pump which as far as I can tell it's the same as the OG Z pump. I think it was 225 bucks but it does kick ass! I doesn't miss a beat. We also cut the stock tank open again (first time to put new lines in, the OG were rusted bad) and added a filter on the pickup. It's a fun car to race that's for sure! Waiting on Keith to advise us more so we can get faster!

[icehouse]

[510rob]

I thought all 510's were kick ass inherently?

agreed

[510rob]

Awesome. That’s actually a very simple solution in my eyes. Way better than cutting a hole in the gas tank. Ha. May I ask which fuel pump you’re using on the low pressure side? I have a decent walbro one that I was going to use to put into the injector system, but I’m gonna need to buy a low pressure one for the surge tank.

Another EFI car up here (with an under-car surge tank) is running a Carter high volume low pressure pump to feed the surge tank primary loop, then a Walbro GSL392 to feed the high pressure side to the rail-loop. I don't remember what specific model the low pressure pump is, but it looks something like a Carter P4070 or similar to these things...
https://www.summitracing.com/search/par ... fuel-pumps

[mhinkens]

Thanks for that suggestion.

I was thinking of just running a low pressure version of the Walbro pump I was going to run to supply the fuel rail.

So this one to supply the surge from the oem tank: https://walbrofuelpumps.com/walbro-gsl3 ... -pump.html

And this one to supply the rail from the surge: https://walbrofuelpumps.com/walbro-gsl3 ... .html.html

That make sense?

[510rob]

Makes sense in theory. It all depends on the goal; going to Bonneville? Friday night cruising? Track days?

All you need the low pressure pump to do is keep the surge tank filled; the low pressure pump needs to be able to handle the flow rate of the high pressure pump at your motor's max BSFC plus an engineering 5-10% fudge factor due to variance in applied voltages at each pump. That is probably totally carried away...

Get something that mechanically fits where you need to put it and that is quiet

[mhinkens]

To be clear: this is a street car!

Silly question maybe, why not the same pump then? Pricing is similar for a low and high pressure. Couldn’t I just run another of the same walbro high volume/high pressure pumps?

Update:

Doing a bit of reading here: https://www.radiumauto.com/Blog-Post.aspx

Seems like these two pumps could work well in tandem:

- Walbro, Inline GSL392 = 255LPH@43.5psi
- Walbro inline GSL395 = 130LPH@15psi