This thread now has more technical info on downpipes than it does on EFR turbos on a 4G63

 

Yeah but not really.

 

No point in having EFR turbos if you can't fit them to the car and allow them to breathe as they would like to

 

^ +1

May as well discuss packaging the turbos because 4+ years and 234 pages later theres still SFA EFR results LOL

 

sorry but saying 10-20% better flow from those restrictions? I would say you read too much and lack actual testing. I have swapped exhaust on cars and have seen the difference. going from a 3 inch press bend exhaust to an ultra expensive buschur stainless 3 inch mandrel bend exhaust yielded zero HP on a 400whp car.

 

Marginally.
Neither of them is truly intended to operate in the 1600-1800F range that EGTs get to. To say one is superior is a stretch; while they both offer significant improvement over 304, neither is really the "ideal" material for this application. None of use really blast along at 1600+ EGTs for periods long enough to cause IGC to be a concern either though so it's kind of a moot point.

The head port should actually be larger then the runner diameter to some degree. It should have some excess volume to allow the initial blow-down to exit the valve quickly and then should taper in to recover the velocity as it progresses into the manifold.

I am of the sentiment that you want minimum cross section that can get the job done and focus on stuffing the biggest bend radius in as possible. Bend Radius/Tube Diameter is very important and has a SIGNIFICANT impact on pipe flow losses. I'd rather have a 10% smaller ID and 1.8:1 R/ID ratio then the larger tube with a 1.25 R/ID ratio. That's why I'm not a big fan of weld-els, the bend radius sucks in them.

Hypertune has addressed these issue though by offering bends with larger CLR.

Great looking welds man.

Not all pie-slices are the same man.

Your CFD (appears to be off somebody else's website though?) also looks odd to me as I've done the CFD work along with the basic fluid mechanics courses and that doesn't match conventional pipe flow characteristics. Although, it's highly dependent on the exact bend and flow conditions along with inlet/outlet constraints. Typical turbulent pipe flow though has the highest velocities on the outside of the bend. Too tight of a bend and you end up with flow separation on the inside of the bend which causes eddies to form and huge flow losses.

Pie-slices done correctly however are within a few percent of flow to a mandrel bend of equivalent bend radius. Knowing the correct angles and sizes to get that similar flow characteritic though does take a little bit of knowledge.

But also keep in mind, that "few percent" is based on a PERFECT mandrel bend with zero ovalization of the tube. I've NEVER bought a "perfect mandrel bend" before so I can't really comment on how they really stack up. I can say for certain though, pie-slices done right do have some advantages over mandrel bends in applications that require complex bends.

 

I prefer a double layer of carboard, a box within a box, and soft foam blocks inside. Turbo wrapped in dual layer plastic bags, nestled within the foam . I like the foam to have a smooth radius so that it wraps around the turbo with less restrictions.

 

Fitting that 3.5" downpipe around everything without lowering the crossbrace is some seriously impressive work. I love my MAP O2 eliminator downpipe, but it requires some gigantic crossbrace spacers to fit, leaving the crossbrace hanging lower than I'd like on a street car.

The pie-cut bends may not be ideal, but the 3.5" exhaust already has 36% more cross-sectional area than a 3.0" exhaust, and I doubt a couple of pie-cut bends would come anywhere negating those flow gains.

 

At only 400hp the restrictions are not relevant. The more pressure and flow you have the more it matters. Try that with 700 and above and report the results. Even 2.75" with smooth bends would be fine for that power envelope. Do not assume that just because you didn't see much of a difference at around 60% of the peak flow of that pipe that there isn't one at higher flow levels.

 

the restrictions for this down pipe being discussed are not relevant either. thats my point. and thats using your same logic. the turbo being used is no where near the exhaust flow limits of a 3.5 tube.

 

Is anyone aware of any particular enhanced requirements for oil lines? Either supply or drain? Someone is telling me that the -8 lines are not sufficient and that I need -10. Seems excessive to me. He is currently having problems with one of his turbos smoking and claims that's what is causing it.

 

Then how did he get 400rpm spoolup improvement? Unless those are just anecdotal results?

-8 should work fine if the line is straight, no kinks. These turbos don't use much oil, so there's a slim chance it'll back up in the cartridge. The turbo also needs to be oriented upright so gravity pulls the oil straight down. Good crankcase vents are also needed, if there's excess crankcase pressure it can push oil out of the seals. Of course, don't forget to check the engine for sources of burning oil such as the valvestem seals or rings.

 

Please consider that chet has an X. Also consider that X's have Mivec on both cams. Will a 9 experience 400 rpm spool improvements on a 3 vs 3.5 inch DP? I'd doubt it.

 

At PRI the guys at the Borg booth said to use a -10 drain line.

It still comes down to the fact that the best exhaust for a turbo car is the biggest/least exhaust. Any kind of restriction after the turbine is going to impede performance. Sure there are compromises, but if you can fit a 3.5" downpipe, you should do it.

 

I didnt make any changes to MIVEC or anything in the tune after I installed the downpipe. Litterallly all I did was install the 3.5" dp.

I definitely think that if you are running a large enough turbo, a 3.5" dp would for sure improve spool and overall response.