Morning all. So recently I sold my sidewinder manifold and am looking to do something a little different but want some input first regarding top mount manifolds. First question I have is...

1. Do you think a top mount T4 single scroll manifold will support 1000whp? (think p-fab top mount ELT T4) And currently who has the highest HP top mount setup out there.

2. What RUNNER LENGTH, DIAMETER, and SCH PIPE would be ideal for a high HP goal?

3. What is the largest turbo that can be fitted to a top mount manifold?

4. Can a 4" Downpipe be routed under the car from the top mount location?

5. What is the limiting factor on a top mount? I.E. why can a top mount T4 tubular manifold make the same power but more torque than a long tube sidewinder manifold? (Playing devils advocate here)

I know there are a lot of great sidewinders out there but im difficult and just want to do something different, also I like the idea of having a slightly shorter runner to increase throttle response and bottom end power. Also the fact that a top mount is less prone to cracking than a sidewinder (usually) and you can keep your factory oil filter is also a big plus for me. Oh and also my entire exhaust side of the bay is shaved and tucked so there is nothing at all in that corner. As far as the turbo goes I am running a precision 6870 which if you don't know is the first "small frame turbo" that is said to support over 1000whp, I believe precision actually rates it at 1150hp which is the same as their 7285 PTE. Thanks all and please post photos of whatever tubular top mounts you have seen or are available on the market currently. (No logs please)

 

P-Fab ELT Single Scroll

P-Fab ELT Twin Scroll

 

Custom "Team Ballistics" single scroll top mount manifold

 

I have a pfab t3 and a 3inches down pipe. My pipe runs pretty close to my side frame and runners. I don't think a 4 inches down pipe will fit going down under the car. I have a gt3582r with a 1.06 ar housing. I had a hx35 7 blade with the 12cm housing before and the cold side compressor wheel didn't clear my valve cover.

 

4" down pipe wont work with a top mount. But you could route it out the fender or through the hood if you want something that big. I don't think you'll fit anything bigger than a 35r/6266 on any of those mention manifolds. You could maybe custom make a manifold to tilt the flange further out for more space for a bigger turbo.

 

The top mount with runner lengths and such is very similar to a ram horn style, just flipped around and these designs aren't for big power IMO due to the way the runners curve and space available. Forward facing manifolds with straighter designed runners is what would be best for big power IMO.

 

Yeah I agree, I am thinking of doing a custom top mount for my Gen 2 6870 which cosmetically isn't much bigger if any than a standard 35R but is rated for 1100whp. Im thinking if I can utilize the battery area more and maybe get a little angle on it I could get away with the 4" under car but worst case ill just do a 90 degree out the hood or fender lol.

 

I agree that the straight runners help but from what I have learned/read I think the primary determining factor is the runner length and not the bends so much. As long as there is no sharp bends and the design is gradual slow swooping it should perform. Also design wise the merge collector and wastegate placement can be identical to any high end sidewinder out there. If the ram horn/top mount design was limiting why would big power 1000-1500hp B series, K series, DSM`s, and EVO`s run them? (Playing devils advocate here lol) I agree a sidewinder is a definite way to make big power but I am trying to see if it can/has/will be done on a s2k. Thanks for the input, good point!

 

I would love to ultimately run this design (full race twin scroll b series t4)

 

Im putting together a custom kit using Pfab t3 topmount equal length mani. I went this route due to a couple reasons. Quicker spool, produce power that of longer runners, no need to relocate oil filter, and I personally like the look of where the turbo sits on a topmount. Can vent the hood and feed cold air or draw out hot air directly over the turbo/dp.
Main issue is having to relocate battery, fuse box, and ac lines. I'll be posting a build thread soon but I got side tracked and bought some 17x10 ce28, spec r springs, and new tires....kind of mad at myself for prolonging my already 2yrs of collecting parts, but I couldn't pass up on my favorite set of volks -__-