Fuel System on Firewall

Hi GRM, 

This is my first post here but I've been a long time reader. 

I'm attempting to determine if I've created an unsafe fuel system. Based on my research it seems like I have but I'm looking for more feedback before I start back in to fabrication. 

I mounted my FPR, Filter, and Fuel Rail on the firewall and ran stainless lines for the feed and return. I didn't think too much about it as some of my other vehicles which I've taken to HPDEs have this configuration both from the factory and what I've done in the past. 

After doing some further research it seems like this is banned from drag racing. I don't intend to drag race this vehicle but I do plan HPDEs and I'm curious if I should relocate these components and what the safety concerns are. Could those more knowledgeable let me know? 

Attached are pictures of what I've done. 

Thank you

That looks totally fine to me.  A lot of OEMs mount fuel stuff to the firewall (CRX).  I'd just make sure there are no holes in the firewall that can get into the cockpit - I mean thats what it is, a fire wall.

Looks top notch BTW

I'm guessing that you ran the feed and return lines up the transmission tunnel and that is what's giving you pause correct? Also is that a 280Z?

Looks freaking great to me.  Make sure that the fuel pump circuit is controlled with a cutoff switch. Run one more line for the fire suppression nozzle if you're really concerned. 

In reply to Dusterbd13-michael :

Whoops didn't hit reply.

The lines are tucked up in the tunnel and this is a 240z blowthrough turbo (triple sidedraft carbs)

What's been giving me pause is the feedback I've received from drag racers (I'm not a drag racer) is the firewall can and will deform in a crash, the lines by the bellhousing/clutch within a distance should be shielded or stainless braided in the event of clutch explosion, and generally if there is a fire on the firewall smoke and flames will enter the passenger compartment much quicker

Maybe not ideal for those reasons they pointed out, but it's not a bad setup, and not different from what a lot of vehicles had from the factory. If you're not worried about passing NHRA safety inspection I'd say keep going.

In reply to GameboyRMH :

Not worried at all for NHRA tech. I'm not building to any class or rules...maybe when I'm long gone and this car is in a museum somewhere 

Leanings towards just moving forward. Running out of time and other vehicles need to move in the garage.

Do you (or anyone else) know of any tech rules at open track days prohibiting this? I've never been questioned on this at Buttonwillow or Laguna Seca. My Integra type R has the fuel filter bracketed to the firewall too as OE

In reply to Dat73Z :

Unless we are talking top fuel drag racing, I don't get those concerns. 

Yes, a firewall can deform in a crash. Is there any panel or frame component that will never deform in a crash?

Yes, the lines should be protected from hazards. Isn't the exposed moving driveshaft a bigger risk than the clutch exploding with enough force to shatter the bellhousing and still cut the lines?  I know a clutch CAN explode (and come through the floor, etc), but again, that with the stresses in drag racing. 
 

A fire on the firewall?  If your penetrations are sealed, you've got to have a pretty significant fire to compromise the firewall. By that point, hopefully you have already exited. 
 

Sometimes people overthink stuff. 
 

Your car looks great!

Beautiful work. 

I just added a surge tank in the trunk of my 200sx racecar. Rules required all fuel components are separated by a firewall... So I built an aluminum box around it. It was my least favorite project ever on a racecar and I didn't do a very good job. In hindsight I should have bought a surge tank half the size and mounted it under the car or in the engine bay, and saved all the trouble. As long as you have quality components it should be just as safe or safer than stock. 

I'm going to disagree and say move them. If a flywheel /clutch or convertor explodes you have the risk of shearing off the lines. At that time the electric fuel pump will continue to pump fuel unrestricted until the fuel in the carb bowls is used up (assuming an oil pressure pump shut off ). That can be quite a bit of fuel in a short period of time with an electric pump and 1/2" feed line. Likewise, running the feed and return lines in the trans tunnel also creates a problem if a driveshaft or universal joint lets go. Up the passenger side of the car on the outside of the frame in the firewall area is safer. You really don't want fire that close to your feet if things go bad. Also you'll be increasing the temp of your fuel with the system in it's current position and with a return line you'll warm up fuel in the tank as well.

You may not think your current driveline combo could break but what if the next owner decides to put a different combo in reusing your fuel system? Say a V8 with enough power to break things that would shear the lines. Moving them now might save a life.

Many years ago I had a car with aftermarket pressure regulator mounted to the firewall of a car. Tech inspectors at a HPDE track day (SCDA at Lime Rock IIRC) let me run but suggested I move the lines to a protected area. Then I failed tech at a drag strip and figured I'd better move it before any more events of any type since it sucks to arrive at some type of event planning to drive and then spending the day as an observer.

Nhra firewall rule has to do with the clutch/converter/flywheel letting loose. Not uncommon for those kind of cars especially with old (cast iron) parts. 

If it were really a concern one could shield the lines in and around the bell housing area.

Thanks for all the responses. A lot of good points to consider. In my redesign originally was planning to terminate the hardlines around the firewall and run braided along the framerail and wrap around the engine. Although I'm not going to drag race I've seen a lot of high HP drag datsun Zs running this way. My engine dynod around 450hp/trq at 15psi of boost at the flywheel I think so it's definitely getting up there to parts breakage, especially if I crank the boost up. 

Thinking about this more, the OEM configuration of the early late 60s-early 70s Z cars was running the lines through the trans tunnel basically what I duplicated here. By the late 70s 280z I think they had moved the lines out of the tunnel and ran them under the car by the frame rails. 

This came together quickly to get the car done and I should've put more thought into it. Ultimately I think I need to completely redesign the system and run the lines out of the tunnel with some skid plates or shielding for off track excursions and meet the engine at the front of the car. This will likely need to be a project for another day. 

I'd be worried that in a good frontal punt, the engine will crush the fuel line distributor/fuel pump. It looks like it would be easy to move them over to the passenger side.

In reply to VolvoHeretic :

The engine would need to move back 4-6" and the head would have to flatten the hood latch area first, but these cars are built like tin cans and any frontal impact beyond 20-30mph will pancake the entire frontend. 

Definitely something Ive been noodling on...the joys of driving vintage I suppose

In reply to Dat73Z :

Why don't you just install an inertial cut off switch?

Pegasus Auto Racing Supplies has them for $60. 

In reply to Tom1200 :

I have one in my system. I can't remember what car it came from but I grabbed it from the trunk of some GM or Ford at the junkyard maybe a decade ago

I have intentions to do something similar on mine. Yours looks really good. 

In reply to birdmayne :

Thanks. If you're going to do it knowing what I know now I'd recommend staying out of the tunnel for safety purposes and simplicity. 

I basically did this iteration following closely to the stock 240z. I used custom machined aluminum spacers where the stock clamps would go and did maybe 20 or so bends per line to hug the tunnel tight. 

I'm working on a revised design now which is more of the 280z pattern by the framerail. It'll be much easier and also your runs will only need a few bends per line which would also be better for flow. Most importantly if the driveline lets go you hopefully won't go up in flames. 

I've attached pictures of what you're up against if you go in the tunnel (I have finished pics too if you want them to reference...these were in progress on my phone).