Exhaust out the hood or the fender?

[zboi]

I have a turbo ls 240z. Right now I have the turbo dumping kinda out the hood, through hood vents. My hood is like this one: 

 

Problem now is the hood vents are getting melted, and a bit of the fumes are getting into the car. I can either cut an opening in one of the vents to have the exhaust fully exit the hood (I had it that way before I put the hood vents on). Or have it come out the fender near the battery. I don't really want to do the fender exhaust since my battery area is mint and it probably wouldn't be good for the value of the car, but that said it would be the best place for it as there would be no worries of fumes or rain. 

What are your opinions?

[AydinZ71]

Apologies. I have to admit, I had a bit of a chuckle when I read this (melty melty). Yes... the exhaust will damage your finish. Primarily from the heat but also from chem's in the exhaust itself. If its FRP, it will destroy your hood unless you clad the area within several inches with an SS or AL heat-shield. Even then, that hood will have an expiration date on it. 

 

Unless its a drag-strip car and you are wearing a respirator, empty the exhaust behind the driver. Where is entirely up to you. There is a reason the old Cobra's have the exhaust run along the rocker and exit behind the driver. Its just impractical to have the exhaust dump ahead of the driver for something that is meant to be driven on the street. Just my opinion of-course. 

 

The whole exhaust out the hood or out the front fenders looks cool, but its just not practical. That is a lot of exhaust out that motor, and with a turbo you will be dumping large amounts of fuel to keep the turbine spooled between shifts and will be running rich in-general under boost. Carbon deposits are for-sure, unless the pipe is sticking way-out. Like several inches. 

[zboi]

Hood is the stock hood with fiberglass vents bonded in. I can only squeeze a 2" pipe between the firewall and passenger exhaust manifold so would need to transition the exhaust down big time. Seems like it would kill the power, also would need to rewire the car as a bunch of factory looms are there asking to be melted (and a brake line). When I had it coming out of the hood before it was only about 1" above the hoodline, was working fine without residue on the windshield or fumes. Maybe that was alleviated some due to all the high pressure under the hood also shooting out of that hole, may not have the same effect with dedicated vents now. Only place I could dump it otherwise is down into the ground in front of the steering rack.

[AydinZ71]

Having a hard time following the locations you mentioned but it sounds like it would be a pain to re-route. S30’s have a massive underutilized amount of space behind the front wheels in the wheel well. If I could not reroute the exhaust to the rear of the car, I’d consider a hole through the wheel-well from the engine bay. Then I’d route down and back and have them exit the front fender just before it meets the rocker. It will still stink at idle but at least the low air pressure here should carry the exhaust away fairly quickly when moving. 
 

you can dump below your engine/suspension/steering rack but I think your engine bay will become quite sooty over time. Exhaust being really hot is going to want to “rise” once the momentum from the pipe is no longer a factor. Hence, your engine bay will be a stinky mess at idle or when not moving. 

Edited August 8, 2022 by AydinZ71

[Dat73z]

On my friend's former turbo nitrous LS he dumped it out the pass fender. 

 

I'd rather do that than the hood. It'll keep fumes down and your windshield cleaner. 

[AydinZ71]

@Dat73z  yep that’s looks like what I had in mind 

[Dat73z]

You could also likely clean up the routing a bit as well and gain some space in that area. The muffler was added due to California Vehicle Code 27150 I believe which requires all street vehicles to be equipped with a muffler