top mount vs bottom mount (turbo manifold)

[tvmendoza]

Hello, i am planning to get rid of my ssac top mount manifold, but i want to make my own manifold. Any thips will be great. but what i want to know right now is what would be better, to do it top or bottom mount? i renember Ivan saying that botton mount was better for left side exhaust. but i am not sure how harder will it be. zer...ge=2 I am going to use all the jgs parts:http://www.jgstools.com/turbo/index2.html

Thanks for any input.

[hannibal]

Well, there arent very many bottom mount T3 manifolds around. And I dont know if I'd call Ivan's mani a true bottom mount. To me, that implies the turbo sits below the exhaust ports on the head (like the stock SR setup). IMO, the only possible advantage is smoother downpipe routing like Ivan mentioned.

If youre going with the JGS parts, then youre gonna use the JGS top mount manifold, right?

[savatoge]

Well, there arent very many bottom mount T3 manifolds around. And I dont know if I'd call Ivan's mani a true bottom mount. To me, that implies the turbo sits below the exhaust ports on the head (like the stock SR setup).

This was Ivan's manifold he made available when he was at Sound Performance/Phatka-t...looks like a bottom mount to me:

IMO, the only possible advantage is smoother downpipe routing like Ivan mentioned.

There are other advantages in addition to simplification of downpipe routing...Ivan's own words:

"The scroll of the turbo dictates bottom mount is better...We can run shorter runners with a bottom mount...Keeping the turbo lower keeps the center of gravity lower...Compressor housing doesnt get baked from being over the header..."

Now that Ivan is over at AMS, the word is that AMS will be releasing a KA-T turbo kit in the near future and it will employ a bottom mount manifold configuration. If you've seen any of the AMS DSM and Evo kits, some of those pics are about as close as you can come to turbo kit pr0n. So I for one can't wait to see this AMS KA-T kit when it comes out!

If youre going with the JGS parts, then youre gonna use the JGS top mount manifold, right?

The interesting thing about the JGS log style manifold setup is that you can do a top mount, a bottom mount...

...or even a side mount setup:

[BlackFlag_s13]

You don't have to trip about clearance...

[hannibal]

OK, I realize my definition of a bottom is flawed.

I never considered the issue of the manifold heating up the compressor, although that JGS top/side mount seems better in that sense than the old PK bottom mount.

[savatoge]

although that JGS top/side mount seems better in that sense than the old PK bottom mount.

Yeah, the side mount setup is interesting, as it alleviates problems with heat in regards to the master brake cyclinder plastic reservoir and/or downpipe routing issues with the master brake cyclinder and hard lines. However, when you go side mount, you might have to relocate the power steering reservoir (depending on how creative you get)...that is, if you plan to keep your power steering. Not a problem for some, but for others, this provides yet another reason to go with a bottom mount setup.
Modified by savatoge at 11:20 AM 3/1/2006

[hannibal]

FYI, JGS's DOHC kits come with a PS reloaction kit.

Is a side mount any less stable than a top or bottom mount? With a top mount, the turbo's weight is sitting on the manifold, and with the bottom mount, its essentially hanging from it. But a side mount puts a lot of the weight off to the side. Seems like it could promote cracking and theres no good way to brace it.

[Iamjohnhayes]

i kind of like the bottom mount idea the only problem i could see is that it might cause issues with the plumbing of the intake from the filter and maf depending on how far forward or back it is

---Shameless plug---

i have a side / bottom mount for sale if anyone wants it (KA24E)

[Jookmasta]

i run a jgs side mount...........power steering has to be relocated. no issues with mbc tho. no need for a shield. the only issue i could see is that ur limited by the size of turbo you can run.

[tvmendoza]

that is true and i was not taking into consideration. Thanks, maybe what i can do is getting a flexible hose. I will be ordering everything on a week or two and i will try to post some pictures. before i finish welding so you can tell me what you think. I like the idea of having a bottom mount because there is only a few people with it. Thanks for your input, keep it coming.Tona

[jrb92se]

ive been searching also and have not been able to find many bottom mounts with a t3 flange they make them for t25\28s i was going to pick one up and try and get a t3 flange welded on but didnt know if it would be worth while to do so

[crzycav86]

The only advantage I see in a top mount over bottom mount is that you have more room to fit a big compressor. the phatkat manifold and turbo comes close to having clearance issues, as did my bottom mount/t3 turbo that practically hugs the block.