Mission May: Complete Twin Turbo FD V8
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
that is exactly it, spark plug clearance. the damn plugs are at an angle to head.
you can see in this pic if i angle the runners clockwise (which i have to due to turbo placement), i decrease the plug clearance a lot
log manifolds in general are poop as you know already :p i didnt want to go with tubular style manifolds either cause they takes too much damn space and i wasnt aiming for anymore than 700bhp
you can see in this pic if i angle the runners clockwise (which i have to due to turbo placement), i decrease the plug clearance a lot
log manifolds in general are poop as you know already :p i didnt want to go with tubular style manifolds either cause they takes too much damn space and i wasnt aiming for anymore than 700bhp
And why stainless for the intercooler piping instead of the much lighter aluminum? I used to make mine with stainless before I had the equipment to weld aluminum.
Hope it doesn't sound like I'm picking you apart...I just want to understand your decisions.
What EMS are you going to run?
That makes sense. So my next question is, why not stainless? :P I don't doubt that the SCH40 steel will hold up really well considering the rather weak EGTs of a piston engine compared to a rotary, but in bulk the supplies in stainless aren't much more than mild steel. Of course it requires much more fussy welding.
And why stainless for the intercooler piping instead of the much lighter aluminum? I used to make mine with stainless before I had the equipment to weld aluminum.
Hope it doesn't sound like I'm picking you apart...I just want to understand your decisions.
What EMS are you going to run?
And why stainless for the intercooler piping instead of the much lighter aluminum? I used to make mine with stainless before I had the equipment to weld aluminum.
Hope it doesn't sound like I'm picking you apart...I just want to understand your decisions.
What EMS are you going to run?
Other minor reasons are low carbon steel expands less than stainless steel, don't need to back purge low carbon steel, low carbon steel warps less than stainless steel (not only when welding, but during service too).
You are right, stainless steel weld elbows cost about $1 more than steel in bulk. So cost really isn't a factor.
Ideally, the ULTIMATE manifold would be thick cast stainless steel! I'm planning to make a kit out of this if this works out well in the future. When I get to that point, I will definitely be making cast stainless manifolds because the cost will be justified, the setup well be proven, and there will be no welds to crack
I used to make aluminum intercooler piping before. You're right its lighter. For my current setup, it'd be about 6lb lighter. Aluminum on the other hand is absolutely garbage in terms of being scratch resistant! After a couple times removing the piping in and out of the car, they'd be scratched easily. **** even putting them on the work bench meant they'd get scratched! I can throw my stainless pipes onto the table, across the room (don't ask me why), and they don't get scratched or dented. Another reason is cost. I can get stainless mandrel bends for a lot cheaper than aluminum mandrel bends. $13 vs $22 on average. So it costs less, looks better (yes I've got ricer tendencies hehe), and weighs slightly more -- this is why i use stainless over aluminum.
Joined: Feb 2001
Posts: 29,798
Likes: 128
From: London, Ontario, Canada
I like to use low carbon steel for turbo manifolds because when you weld it the heat affected zone (HAZ) has composition that's very similar to the base metal, therefore the weld has a very similar grain structure to the base metal grain structure. This is because there isn't enough carbon or other alloys to form brittle crystalline structures. Stainless on the other hand will rapidly form brittle crystalline structures at the HAZ. Even though stainless has better creep resistance than low carbon steel, if you consider in the composition at the HAZ, the low carbon steel welds have better creep resistance than stainless welds. You'll notice most properly welded stainless manifolds will crack in the HAZ. (If they crack in the center line of the weld, that is just a bad weld -- wrong filler, little penetration)
Ideally, the ULTIMATE manifold would be thick cast stainless steel! I'm planning to make a kit out of this if this works out well in the future. When I get to that point, I will definitely be making cast stainless manifolds because the cost will be justified, the setup well be proven, and there will be no welds to crack
downpipe coming together slowly. still gotta recirculate the wastegate dumps. thanks to my buddy brian for helping me out major under the car.
right side setup:
left side setup:
right side setup:
left side setup:
