2084 Turbo Build

[Schweg]

Nice!! Look forward to the results!!! More then enough time to get it tuned up and ready!

[kangaboy]

Well, time for a little update. I got the motor broke in, changed out the oil for the second time (first after initial break in, and second after about 75 miles of driving), and everything on the bottom end seems to be jiving well. I did a bunch of little tweaks and updates to get everything ready for the track day this weekend. One big thing that I am still working on solving is the fueling system. I don't REALLY know what the issue is with it, but I'm hoping it's just a fuel delivery issue, as my fuel pressure dropped to 23psi the other day when I was tuning at about 5000rpm and 18psi of boost . Fuel pressure seemingly went down 1:1, instead of up, and that caused the ol' AFR safety system to kick in and say "stop what you're doing". Went home, looked at the log and was really confused how it was happening...I had this same fuel system and injector setup on the 1776 and got that motor up to 25psi of boost at 5000rpm with no issues. Maybe this new motor takes a bit more fuel? With the car off, I turned on the fuel pump and hooked the fuel pressure regulator to a bike pump and put 20 psi on it...I took a log while I was doing this and sure enough, it rose from a base fuel pressure of ~40psi up to ~60psi. I THINK this helps me rule out the FPR as failing, and makes me think the Airtex Amazon pump isnt keeping up with the flow needed for the now bigger combustion chambers. IDK, but I ordered a new 020 Bosch fuel pump (supersedes the 044), and need to replace all the flex lines on it while I'm at it, along with a new fuel filter. I also made note that I need to put the filter AFTER the pump, as I currently have it in front of it. Most folks say that fuel pumps push better than they pull, so while having the pump in front of the filter could have been causing a little issue, but likely not. Also, I have the poor man's fueling method going with the stock (1/4"?) line coming from the fuel tank and going into a T to supply fuel to the system. I don't know when, or if there is a cut off to how much HP this can supply, but I imagine it has a hard limit.
Anyway, assuming I can get this fueling issue figured out by Sunday, I'll get some time slips for the new motor. My only goal for the strip has been to go faster than I did last time, and so far I have been meeting it. With the new motor sporting a few more horsepower than the 1776, I feel like it will be no problem...assuming my stock T1 Trans can hold together for a few runs...but that will be another story all together when that baby give out.
I'll get some pictures up regarding the fuel system and the current state of the bug in general. I missed a bunch of stuff, but gotta start my updates somewhere.

[madmike]

Better pump and bigger fuel line

[kangaboy]

Better pump and bigger fuel line

Pump just came in the mail last night. Going to get some fittings from the local shop and get it plumbed up tonight.
A quick google peek says that my 3/8" feed line should be good for 600hp...but I'm mostly concerned with the 1/4" line from the tank to the T.

[Ol'fogasaurus]

Better pump and bigger fuel line

Pump just came in the mail last night. Going to get some fittings from the local shop and get it plumbed up tonight.
A quick google peek says that my 3/8" feed line should be good for 600hp...but I'm mostly concerned with the 1/4" line from the tank to the T.

Interesting question! Going from the smaller dia. hose to the larger dia. hose could cause a swirl or at the worse maybe some air bubbles. This is a guess based on something that happened to someone I knew but it was also a long time ago too.

Lee

[Clonebug]

Tap the stock feed hole with a 1/4 npt pipe tap and put your tee there. I did that and have a 1/2 inch feed line off one side to the pump and a 1/4 inch barb for the return.
There are pics in my build probably around page 20…….

[Schweg]

That 1/4 return shouldn’t restrict fuel flow. If anything I would assume pressure would increase due to it “stopping” flow.

[Clonebug]

He has a 1/4 inch short line feeding the pump….. at least that’s how I understand it….

[Ol'fogasaurus]

If I understand what is going on correctly: the "Tee fitting" brings fuel out of the fuel tank as a "gravity feed" process unless there is a fuel pump from the tank and the tee is there. It goes into the larger dia. pipe to the fuel pump where it is then pressurized into the fuel distribution area (carbs/FI, etc.). The "return line', I would suspect, is still pressurized (at least somewhat anyway) going back to the Tee from the fuel tank. The pressurized fuel could be then drawing some fuel out of the fuel tank as it makes its return to the fuel distribution area.

Again, it's been a long time, but I have seen/heard something like this happen before.

Lee

[V8Nate]

Tap the stock feed hole with a 1/4 npt pipe tap and put your tee there. I did that and have a 1/2 inch feed line off one side to the pump and a 1/4 inch barb for the return.
There are pics in my build probably around page 20…….

Page 41, that was good to re read the history of the carb to fi days:)

[kangaboy]

Yep, sounds like I explained it well enough that everyone is on the same page. 1/4" line from the tank via the stock feed to a T, then 5/16 hose barb on one end going to pump and filter, then to fuel rails, and then from fuel pressure regulator down to a 1/4" return line, and then going back into the other end of the T.
I actually meant to post this over in my previous thread. I figure that I am done building the 2084 and have it running, it's time to get back to my main page. I got a bunch of fittings and stuff this afternoon, so I will update my main build page with all the fueling changes.
Also, that pic that Nate just posted from Clones build is the way I need to go. Race day on Sunday, so wont have time to take it out and do it in one day, so hoping that it can live the way it is for now. I'll know after this weekend if the new Bosch 200 fuel pump solves the previous issue though.

[GS guy]

Ditto Clone's recommendation, or get the CB Tee fitting:
https://www.cbperformance.com/product-p/6483.htm
CB says it screws directly onto the fuel tank fitting? 1/4NPT outlets.
Sounds like that little 1/4" line out of the tank is starving the pump.
Also, make sure any "pre-pump" filter is in the 50-100 micron range. Use a finer 8-15 micron filter post-pump.
Jeff

[Bruce.m]

Mental checklist

Pump creates flow
Restrictions before the pump reduce flow
The restriction downstream creates pressure.
Excess demand = no spare flow capacity to create pressure.

[Schweg]

Yeah I misunderstood for sure. The CB T or a brass t would get you sorted out with more flow for sure.