How much faster is a GT3 RS than a stock E30?

[Nygdup]

Nice Vid -

I have a few questions about your fuel tank setup, since I'm looking into doing the same thing for my ChumpCar.

-Did you convert completely to the newer tank and pumps with high-pressure feed coming from the tank? Or did you keep the low-pressure feeder and run the stock early-model external HP pump? Which pumps did you end up using?

-Surge tank or the new tank only?

-Were you able to run longer than 2 hours?

-How much gas did you put back in when you filled up?

TIA!

Hiya!
Halston's teammate on the car here. I'll answer the questions since he has no clue what we ACTUALLY do to make the car work.

We installed late model tank with late model fuel pumps. The old dual pump was completely removed.

We didn't measure the gas we put back in. We're not exactly sure how far down we ran the car, but it was showing empty on the gauge. Judging by our previous fuel consumption we should be able to run a full two hours, or very close to, on the new fuel tank.

[Nygdup]

Missed Halston's response.. I guess he didn't notice we removed the surge tank.

[Wh33lhop]

Is the late model tank really better for starvation? IIRC the early model was better with the lift pump feeding the inline HP pump.

[Nygdup]

We read the same thing. Either that is false, or we had something wrong in our old style system. Getting the full 2 hours even with no starvation was going to be tough with the old tank, so going to the new tank was the decided path we took.

[dinanm3atl]

I have no clue? roflmao

I hate you Rich.

We did at least 1hr 20min on track before refueling. This was 30 minutes longer than our BEST before starvation before. We also drove it to the track and home(2 hr round trip). I suspect we have 1hr30-1hr45 before we see starvation. However I was in the car with the light flickering going up turn 1 at Road Atlanta while pushing it. That is when you would see the worst starvation.

I read the same thing. Early SHOULD be better. The issue seems to be rust in tank on early cars. Thus the transfer pipe is blocked. Or you have a combo of weak pumps and the above problems. We could run ~45min and we would see starvation. Based on how much we would fuel on a pit stop at that point we were seeing it starving at more than half a tank.

Late model creates a swirl effect to suck fuel over from the passenger side. The return also dumps into a bowl where the pump sits. It also has baffling in the tank.

[Wh33lhop]

My early model starves at under half a tank, but the lift pump is dead. Haven't replaced it yet.

[nando]

I have never experienced starvation in my car, even on long, hard right hand sweepers and the reserve light on. I did a whole day of autox on 1/4 tank once -granted autox is quite different, but on our bigger courses there are some pretty good long sweepers.

in a steady state, the dual pump system is better - as it can pump more fuel volume for a given pressure (especially if you upgrade the external pump). as for starvation issues, I have no idea, I've only got one E30.

[NigelStu]

nando - are you running the early setup?


Running full-out from a FULL tank, we get the light to turn on about 1:20-1:25 in to a race and start to have stumbles that impact forward motion (and drivers anxiety) at about 1:35-1:40. Looking to be able to get to an easy 2 hours so that we can take running out of fuel out of the equation. I figure we need about 14 gal to run a full 2 hours. The new tank plus a surge is what I'm looking at to make this happen without any stumbles.


I was not aware that the return dumps into the HP pump side into a small in-tank surge. That might be all we need as long as I can make sure the left side of tank an pull all of its fuel.

Looking forward to hitting the track next year!

[nando]

no, I have a late model tank.

[TobyB]

I put a late in- tank pump into an early tank, made sure the crossover was good-
and can get it to pretty darned empty (light on for some noticable number of laps)
with no stumbles.
I had to add a return line, but that was it.
I was expecting to need to put a 1- way flapper into the crossover pipe, but haven't had to.

t