4" downpipe on a bottom mount manifold?

[slowgsr]

Well, I just quickly made up this downpipe yesterday because I was bored. Its NOT welded yet, since incase I have to 'tweak' the bottom bend that goes under the pan to fit the rest of my exhaust easily I will be able too. However, It should be fairly close.

Well, I had to use some 'cheater' bends, Since I am using a bottom mount, I didn't have room to get the full radius 4" bend in there.

The car has a full 4" exhaust with no muffler, its very straight and very 'un-restrictive'. Im just worried that the sharp bend coming off the turbo is going to cause too much restriction?

I don't really think it will be an issue since the rest of the system is a very free flowing 4", and it is afterall 4" turbo-back? What do you guys think. I mean there isn't really much I can do about it, but if it may be a big concern, I could put a backpressure sensor in the downpipe to make sure its OK.

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I must say, that 4" stainless is hard on my bandsaw blade! Don't mind the vice grips, I only had 1 bolt kicking around and had to improvise.

 

[biglady112]

It looks great. This is how I roll.

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[dsmdeliveryboy]

Wow, both cars are very impressive looking.

 

[Imback]

I think the transition and radius of it are fine. I've seen tighter ones. Are you going to have the pipe coated afterwords?

 

[slowgsr]

I'm not sure, if anything I will wrap it. It's all 304 stainless.

 

[99gst_racer]

Great work, Eric. That's some excellent pipe fitting there.

Don't worry about it being too restrictive. I've seen much worse from cars that performed very well, so I think you'll be just fine. I can honestly say that I would completely trust running that on my own car. I know some of the turbine outlet bends have very sharp, less than desirable angles, but you've done a good job at utilizing the space that you have to make it the least restrictive as possible.

 

[slowgsr]

Thanks, Ill get some finished pics on here and update the thread once its all welded up and connected with the rest of the exhaust, on the vehicle etc.

 

[slowgsr]

Heres a couple of 'finished' pics.. I Just have to have the vband welded to the aluminum, but thats all gravy.

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The waterpipe DOES fit.. However, I will not be using a factory full length waterpipe, since im moving the outlet on the rad to the lower drivers side rather then the lower passenger side.

I had to 'modify' the dipstick, but its done, it was a huge pain! However, The dumptube(s) will dump right infront of the downpipe between it, and the crossmember, so I needed some space there.

I also plan to add a before the flex under the pan somwhere to help support the downpipe, 4" stainless is damn heavy

 

[92tsiawdguy]

this is my 4" exhaust

heres a link 27197 1306506704976 1299780231 30991285 1559409 N - DSMtuners Gallery

27197 1306506464970 1299780231 30991284 877065 N - DSMtuners Gallery

28178 1308044503420 1299780231 30995333 5390412 N 670009 - DSMtuners Gallery

 

[95GreenGSX]

I don't really think it will be an issue since the rest of the system is a very free flowing 4", and it is afterall 4" turbo-back? What do you guys think. I mean there isn't really much I can do about it, but if it may be a big concern, I could put a backpressure sensor in the downpipe to make sure its OK..

It looks great! This is one of the most non restrictive 4" exhausts Ive seen. Looks like your doing a great job, keep it up!
Got to love those forward facing oil filters!

this is my 4" exhaust

Yours looks like its a 3" to 4". His is a straight 4". Its nice, but doesn't really compare.

 

[bwhite]

that looks nice. I dont even want to show the one i just made.

 

[92tsiawdguy]

how does mine not compare? It's 3" for about 3 inches. The exhaust is moving so fast at that point it's not restrictive.

 

[bwhite]

Here is my 3 inch 409 SS downpipe. Do you guys think its going to be a problem by the oil filter? Dont look at the welds please.

 

[92tsiawdguy]

you better wrap that thing or it will cook the filter

 

[Boosted98gsx]

you better wrap that thing or it will cook the filter

+eleventy

 

[slowgsr]

I'll get some pics up tonight, it's all tig'd up and been installed.

 

[bwhite]

You think I should remake it?

 

[95GreenGSX]

how does mine not compare? It's 3" for about 3 inches. The exhaust is moving so fast at that point it's not restrictive.

It looks like 3" pipe for a bit more than 3 inches. The whole problem with the 4" was the bend right off the turbo. The OP did a great job with the bend and the whole exhaust. 3" tubing is a bit easier to make the bend. Im not saying yours looks bad, I like it, its just easier to make the bend rather than the 4" pie cut. Or just 4" in general.
I like your return line, did you weld the -12an (assuming) on to the pan?

I'll get some pics up tonight, it's all tig'd up and been installed.

Stainless down pipe to aluminum exhaust? Looks good, I like.

 

[92tsiawdguy]

if my turbo had a 4" exit i could have use a tight radius 4" 140* bend that would have been easy. i mocked it up on my hx55 but for now im running the hx40. and yes thats a 12an drain line with a welded bung in the pan.