Cutting gas tank, doing side exhaust, adding rear diffuser.

MAMotorsports · 10-06-2015, 01:11 PM

I think we have a cut 370 tank sitting in the shop here somewhere if anyone is looking for one. Has worked for us in the past as a temp thing until a customer goes to a fuel cell. They have seen many track days. 350Z guys have been doing it for years.

synolimit · 10-06-2015, 02:48 PM

Quote:

Originally Posted by 2011 Nismo#91

Your way is definitely much more cost effective. Going easy on the track got me 8.4, harder was getting something around 6-7. Depends alot on the track/driver =P and I know I'm not that good.

Chris Forsburg did it so I hope it works. Now just checking to see if we can tap into the passengers fuel level float since we are removing the drivers float so my fuel gauge still works! I pray the ohms are the same.

synolimit · 10-06-2015, 02:53 PM

Now that the tanks out I'm taking the time to delete all the evap. Once again more damn rear weight removed!!

!

This was easy. My TB coolant lines have been deleted for years! So all I had to do was pull the sensor and cap the manifold nipples. In the rear I just cut all the metal lines and pulled everything out. The electrical plugs got taped up and I removed the fiber glass side bottom and pulled the 1/2" line running down the side up to engine.

I've also picked a Y pipe. Instead of modding my X pipe I'll just sell my full CBE.

synolimit · 10-06-2015, 02:57 PM

Quote:

Originally Posted by MAMotorsports

I think we have a cut 370 tank sitting in the shop here somewhere if anyone is looking for one. Has worked for us in the past as a temp thing until a customer goes to a fuel cell. They have seen many track days. 350Z guys have been doing it for years.

How was the pump modded? We were thinking about plugging the nipple where the black accordion hose attaches to that runs over to the passenger side. That way the only fuel pick up will be on the bottom of the white oem surge tank. It's a little black plastic corner with tinny holes drilled in it to feed the pump.

Rusty · 10-06-2015, 05:49 PM

In for the result.

Davey · 10-06-2015, 06:59 PM

Me too.

2011 Nismo#91 · 10-07-2015, 08:19 AM

Y pipe will definitely be much easier to deal with then the X. Keep us updated, sure looks interesting.

synolimit · 10-07-2015, 11:16 AM

Something tells me I'll be doing resonator after resonator instead of exhaust pipe haha.

MAMotorsports · 10-07-2015, 12:33 PM

Quote:

Originally Posted by synolimit

How was the pump modded? We were thinking about plugging the nipple where the black accordion hose attaches to that runs over to the passenger side. That way the only fuel pick up will be on the bottom of the white oem surge tank. It's a little black plastic corner with tinny holes drilled in it to feed the pump.

Im pretty sure we did the same, but I will see if I can find it and double check. Been a little bit since I looked at it.

synolimit · 10-07-2015, 09:41 PM

Cool, thanks

Davey · 10-08-2015, 05:41 AM

OK so here's a couple of dumb question, because I'm dumb...

The fuel starve is caused by the saddle-style tank, so what you're doing here is actually cutting the other half of the tank off, reducing the capacity by half?

So I imagine that the passenger side bit of the tank is still in place, is there just empty space where the rest of the tank used to be?

I find this interesting because the gas tank in the 370Z is huge anyway and I actually only use half of it (because I can fuel starve the car even on the street when below half a tank just taking long off-ramps at a reasonably fun speed) so I kind of wonder why Nissan didn't just put a small tank in like this in the first place.

In summary, I'm not really seeing a down side to a 10 gallon tank and no fuel starve, especially if this were a relatively inexpensive (and still fully streetable) mod. Although it looks like you are removing a lot of evap/emissions stuff but that's understandable in your case.

synolimit · 10-08-2015, 06:48 AM

Thats correct. Heres a pic of chris forsberg 370z and what mine will look like. Only difference is my CBE will turn out the drivers side skirt in this empty area. This will be 100% DD as nothings changing hook up wise. Evap is here nor there. Just turn the CELs off. Only thing i gotta figure out is how to remount the driver fuels float so my fuel gauge will work. Apparently i cant tap into the passengers float so my gauge wont work. Im thinking about cutting a hole in the new tank and mounting it somehow.

Quote:

Originally Posted by Davey

OK so here's a couple of dumb question, because I'm dumb...

The fuel starve is caused by the saddle-style tank, so what you're doing here is actually cutting the other half of the tank off, reducing the capacity by half?

So I imagine that the passenger side bit of the tank is still in place, is there just empty space where the rest of the tank used to be?

I find this interesting because the gas tank in the 370Z is huge anyway and I actually only use half of it (because I can fuel starve the car even on the street when below half a tank just taking long off-ramps at a reasonably fun speed) so I kind of wonder why Nissan didn't just put a small tank in like this in the first place.

In summary, I'm not really seeing a down side to a 10 gallon tank and no fuel starve, especially if this were a relatively inexpensive (and still fully streetable) mod. Although it looks like you are removing a lot of evap/emissions stuff but that's understandable in your case.

phunk · 10-08-2015, 02:07 PM

Cutting the tank in half will absolutely work great at reducing and nearly eliminating fuel starvation, and you should end up with a 10-11 gallon tank in the end because you will want to cut it closer to the driver side.

All the EVAP stuff, fill breather, and rollover valve etc is in the dead center top of the tank, and you will want to keep that stuff. So strategically cut the tank in the correct location and save yourself a lot of trouble.

Notice the photo I took from my RRP installation page and editted. The yellow areas are calling attention to parts of the tank you want to keep. When I cut that opening in the fuel tank, it was put there intentionally because lots of gizmos are attached to the top of the tank right there, and are still mounted to the panel I removed. This tank was never going into a car, it was purchased new for RRP development and now just hangs out at the shop, so it was fine for me to remove those devices.

You should cut around the red line area.

Like I mention in a PM, you need not even consider the in-tank siphon transfer hose, no need to plug anything or any considerations, just dont hook it up to the fuel sending unit anymore.

The largest struggle with this procedure to the fuel tank you are undertaking is that you will be missing one of the fuel level floats that are essentially variable resisters in a series type circuit.

The driver and passenger side level sensors have a slightly different OHM sweep range... why, I cannot tell you. But this means that fuel level has more value to the gauge on one side of the tank than it does on the other side of the tank.

If you simply bridge the 2 wires together for the missing driver side float sensor, you will basically be telling the gauge that the driver side is full. If you measure the OHMs across the sensor in the bottom position and wire inline a resister that matches, you will be telling the gauge the opposite, that this side of the tank is always empty. This would be ideal because the gauge would always be accurate, it just wouldnt ever reach the pegged full position. The only way you are going to get the gauge to operate entirely OEM like is to add that driver side sensor back in to the passenger side of the tank, which will be a hassle.

It is possible to swap the potentiometer chip inside the level sensor with chips from otherwise identical float sensors. So perhaps if you look in some Nissan service manuals for FWD vehicles that would only need a single sensor, such as maybe a maxima, its possible that the potentiometer chip from one of those vehicles is calibrated to produce the sum of 2 sensors in the Z, either that or their instrument cluster is just calibrated for a single chip of half values like the Z.

PS external surge tanks dont work out well in the 350z or 370z, which is why nobody usually tries them! However, with the tank cut in half and no more need for the jet pump off the regulator bypass.... if you still experience mild starvation with your cut tank, let me know, and I can set you up with everything you need to add an external surge tank for very low cost... you do not need rails or anything crazy. Just a little canister, a cheap walbro pump, and some hoses and fittings. Under $500 easy.

phunk · 10-08-2015, 02:38 PM

Or let me slightly adjust my recommendation... Cut the tank at the red line to begin and gain visual line-of-sight with the things you want to keep. Then alter the vertical cut into a downward slope cut where at the top still matches the red line, but the slice angles towards the center of the tank and meets up with the peak of driveshaft mountain. This should be able to keep all the objects in the tank, and also make sure to not leave a pocket for fuel to get trapped, all while maintaining maximum capacity without sacrificing much surge protection. Obviously the overall smaller you make it, the better it will reduce starvation, but there is a balance to juggle there as you probably dont want terrible range/capacity.

synolimit · 10-08-2015, 02:44 PM

We ended up cutting it in between the rear 1/2" nipple and 1/8" nipple. So pretty much dead center so im guessing 9.5 gallons.

Anything in the tank is now gone. I dont understand your roll over valve comment. The 1/8" line has no valve from what i can see. Its a direct hole right out of the tank below the gas cap unless theres a valve in that small line somewhere. I do find it odd that gas and fumes can just come out of there. To me everything in the tank had to do with the 1/2" nipple that went directly to the evap can.

As for the transfer hose to getting plugged, id feel safer to plug it. Since its about 3" higher than the bottom of the tank it just seems at less than 3" of gas i could get air in there. I dont think it'll hurt to do a plug right?

What im thinking for the float is cutting the white head off the float that gets pinched between the metal ring and gasket wen installed about half way down the white plastic. This will leave about a 1/2" x 2" rectangle. On the tank ill cut a hole or a slit in a flat section near the fuel pumps white head with connector and fill nipple. Ill bolt a thin piece of metal to the plastic and from the inside bring that metal up through the slit and weld it to the tank. Then just need to run the wires oit somehow and seal it up real good.

Ok sweet! Ill let you know how it goes and if i need that stuff.

Thanks for the help.

Quote:

Originally Posted by phunk

Cutting the tank in half will absolutely work great at reducing and nearly eliminating fuel starvation, and you should end up with a 10-11 gallon tank in the end because you will want to cut it closer to the driver side.

All the EVAP stuff, fill breather, and rollover valve etc is in the dead center top of the tank, and you will want to keep that stuff. So strategically cut the tank in the correct location and save yourself a lot of trouble.

Notice the photo I took from my RRP installation page and editted. The yellow areas are calling attention to parts of the tank you want to keep. When I cut that opening in the fuel tank, it was put there intentionally because lots of gizmos are attached to the top of the tank right there, and are still mounted to the panel I removed. This tank was never going into a car, it was purchased new for RRP development and now just hangs out at the shop, so it was fine for me to remove those devices.

You should cut around the red line area.

Like I mention in a PM, you need not even consider the in-tank siphon transfer hose, no need to plug anything or any considerations, just dont hook it up to the fuel sending unit anymore.

The largest struggle with this procedure to the fuel tank you are undertaking is that you will be missing one of the fuel level floats that are essentially variable resisters in a series type circuit.

The driver and passenger side level sensors have a slightly different OHM sweep range... why, I cannot tell you. But this means that fuel level has more value to the gauge on one side of the tank than it does on the other side of the tank.

If you simply bridge the 2 wires together for the missing driver side float sensor, you will basically be telling the gauge that the driver side is full. If you measure the OHMs across the sensor in the bottom position and wire inline a resister that matches, you will be telling the gauge the opposite, that this side of the tank is always empty. This would be ideal because the gauge would always be accurate, it just wouldnt ever reach the pegged full position. The only way you are going to get the gauge to operate entirely OEM like is to add that driver side sensor back in to the passenger side of the tank, which will be a hassle.

It is possible to swap the potentiometer chip inside the level sensor with chips from otherwise identical float sensors. So perhaps if you look in some Nissan service manuals for FWD vehicles that would only need a single sensor, such as maybe a maxima, its possible that the potentiometer chip from one of those vehicles is calibrated to produce the sum of 2 sensors in the Z, either that or their instrument cluster is just calibrated for a single chip of half values like the Z.

PS external surge tanks dont work out well in the 350z or 370z, which is why nobody usually tries them! However, with the tank cut in half and no more need for the jet pump off the regulator bypass.... if you still experience mild starvation with your cut tank, let me know, and I can set you up with everything you need to add an external surge tank for very low cost... you do not need rails or anything crazy. Just a little canister, a cheap walbro pump, and some hoses and fittings. Under $500 easy.

10-06-2015, 01:11 PM	#16 (permalink)
MAMotorsports Track Member Join Date: Jul 2015 Location: Glen Arm, MD Posts: 872 Drives: 370Z Rep Power: 16	I think we have a cut 370 tank sitting in the shop here somewhere if anyone is looking for one. Has worked for us in the past as a temp thing until a customer goes to a fuel cell. They have seen many track days. 350Z guys have been doing it for years. __________________ Daelen @ MA Motorsports MA-Motorsports.com https://www.facebook.com/pages/MA-Mo...C/125379858828

10-06-2015, 02:53 PM	#18 (permalink)
synolimit A True Z Fanatic Join Date: May 2013 Location: Columbus, OH Posts: 5,051 Drives: 2013 Silver 370z Rep Power: 3388	Now that the tanks out I'm taking the time to delete all the evap. Once again more damn rear weight removed!! ! This was easy. My TB coolant lines have been deleted for years! So all I had to do was pull the sensor and cap the manifold nipples. In the rear I just cut all the metal lines and pulled everything out. The electrical plugs got taped up and I removed the fiber glass side bottom and pulled the 1/2" line running down the side up to engine. I've also picked a Y pipe. Instead of modding my X pipe I'll just sell my full CBE. gbrettin and 2011 Nismo#91 like this. __________________ 13 370z-

10-06-2015, 05:49 PM	#20 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 68 Posts: 34,860 Drives: 2011 Nismo GM 6M Rep Power: 2684436	In for the result. synolimit likes this. __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

10-06-2015, 06:59 PM	#21 (permalink)
Davey A True Z Fanatic Join Date: Apr 2011 Location: Indiana Posts: 3,766 Drives: '15 NISMO 6MT Rep Power: 117171	Me too. synolimit likes this.

10-07-2015, 08:19 AM	#22 (permalink)
2011 Nismo#91 A True Z Fanatic Join Date: Mar 2011 Location: NJ Posts: 2,381 Drives: slowly Rep Power: 33858	Y pipe will definitely be much easier to deal with then the X. Keep us updated, sure looks interesting. synolimit likes this.

10-07-2015, 11:16 AM	#23 (permalink)
synolimit A True Z Fanatic Join Date: May 2013 Location: Columbus, OH Posts: 5,051 Drives: 2013 Silver 370z Rep Power: 3388	Something tells me I'll be doing resonator after resonator instead of exhaust pipe haha. __________________ 13 370z-

10-07-2015, 09:41 PM	#25 (permalink)
synolimit A True Z Fanatic Join Date: May 2013 Location: Columbus, OH Posts: 5,051 Drives: 2013 Silver 370z Rep Power: 3388	Cool, thanks __________________ 13 370z-

10-08-2015, 05:41 AM	#26 (permalink)
Davey A True Z Fanatic Join Date: Apr 2011 Location: Indiana Posts: 3,766 Drives: '15 NISMO 6MT Rep Power: 117171	OK so here's a couple of dumb question, because I'm dumb... The fuel starve is caused by the saddle-style tank, so what you're doing here is actually cutting the other half of the tank off, reducing the capacity by half? So I imagine that the passenger side bit of the tank is still in place, is there just empty space where the rest of the tank used to be? I find this interesting because the gas tank in the 370Z is huge anyway and I actually only use half of it (because I can fuel starve the car even on the street when below half a tank just taking long off-ramps at a reasonably fun speed) so I kind of wonder why Nissan didn't just put a small tank in like this in the first place. In summary, I'm not really seeing a down side to a 10 gallon tank and no fuel starve, especially if this were a relatively inexpensive (and still fully streetable) mod. Although it looks like you are removing a lot of evap/emissions stuff but that's understandable in your case.

10-08-2015, 02:38 PM	#29 (permalink)
phunk A True Z Fanatic Join Date: Mar 2009 Location: Chicago Posts: 3,654 Drives: 370 Rep Power: 944523	Or let me slightly adjust my recommendation... Cut the tank at the red line to begin and gain visual line-of-sight with the things you want to keep. Then alter the vertical cut into a downward slope cut where at the top still matches the red line, but the slice angles towards the center of the tank and meets up with the peak of driveshaft mountain. This should be able to keep all the objects in the tank, and also make sure to not leave a pocket for fuel to get trapped, all while maintaining maximum capacity without sacrificing much surge protection. Obviously the overall smaller you make it, the better it will reduce starvation, but there is a balance to juggle there as you probably dont want terrible range/capacity. synolimit likes this. __________________ Charles @ CJ Motorsports : Website \| Facebook \| Instagram \| YouTube Home of the 9 second, stock longblock, stock drivetrain 6MT 370z. 9.91 @ 142mph Last edited by phunk; 10-08-2015 at 02:44 PM.

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