I am finally going to start working on the piping this weekend. So I went by Mike Murillos shop today to pick up the T6 flange I needed and talked to Jeremy for a minute which is their fab guy. All they had was an open flange and I have a divided turbo inlet. He mentioned that they prefer to use the open flange and run 2 into 1 pipe entering the flange due to the LQ4 having issues with pulse timing, which isn't good for the divided inlet. So here is my question. I am going to run with this open flange and probably knife edge the turbo inlet to help the air enter easier. I am running 2.25" pipes from the header. What would be a good size to merge these into before the turbo flange? How long could this run be? I plan to install the wastegate into this merge pipe.

Thanks for the input.

 

The "why does everyone use 2.5" crossover pipe" sticky up top has some posts with flow calculations you will probably find helpful.

 

Read it before. Lots of pages to go through and will look at it again. Thought this would be just as easy. I am having to fit the turbo in a tight space so the single pipe may have to have a little length to it to make it all fit.

 

you have 2.25" OD from the header right? 16ga? call that .060" wall since it varies quite a bit. so your ID is 2.13"

area two of those tubes is 2(Pi(r^2)) or ~ 7.13"

so to get that area out of one tube you need

7.13=Pi(r^2)= or ~3.01"

I'd use 3" tube (2.88" ID) since it's easy to find.

 

Thanks for that work and info. LOL I was figuring 3" would work. Issue I think will be that the single 3" will not fill the T6 flange hole. I think it is about 12.5" total. I just got back online to look at the thread again as well. Curious as to how long this 3" pipe run can be. Does it matter since its the same total ID basically? Also seems like I would want it to have a little length to help with exhaust pulse timing if I can get both 2.25" to about the same length. Which I can probably do with a bed mount setup.

 

Honestly I'd do whatever made the most sense fabrication-wise and ease of access/service-wise. (can you reach the plugs? O2 sensor in a good spot?)

as long as the merges are gentle and the waste gate is as close to the turbine as possible the rest can be sorted out in tuning the gate with the boost controller.

that said, the shorter the hotside up-pipes, the better. you lose heat and energy the longer they get.

 

What is the ID circumference of the T6 opening. Why not merge your 2.25 pipes to match the T6 opening? i.e. remove the necessary amount from each pipe (per ID) to match 1/2 the T6 ID. Use a piece of tape cut to length in T6 flange.

 

Thought about doing that too. My pipe parts should be here today and then I can try to figure it all out.

 

You have a divided housing anyway. 2.25" into each side of a divided flange with 2 38mm gates. Keep the banks divided and be done. I've never heard anything about pulse issues... Any actual data on that? Sounds like BS to me if you keep it divided.

 

I didn't ask for data, but when it comes from Mike Murillos fab guy I would tend to believe him. Either way, I don't want to run dual gates. So I am going to run it as a 2 into 1 and into the flange. I will try to merge the 2 pipes together if I can make it a clean transition.

And my piping did not make it to me yesterday so I wont do anything now until later this week or next weekend.

Also looks like a bed mount. I tried many, many ways yesterday to place the turbo with the Jardine up and forwards and its not going to fit. And I am not changing the cage.

 

If you go with the open flange, I wouldn't "knife edge" the the divider in the turbo housing. That will just confuse the flow.
Just round it so that the sharp edges are gone.

 

Dividing the system will only lessen the effect of interfering pulses. You can also maintain a divided system with 1 gate if you want, Just need a divider. Usually 2 gates are easier to install IMO. And often cheaper than one large one.

 

Is that a divider where the gate goes? I have never seen a divider plate there. I thought the op was referring to the T6 flange being divided.?

 

Yes. Don’t see it much on V8’s because there are very few V8 setups that take advantage of a true divided exhaust system. In the 4-6cyl world it’s super common to run a true dived system with a twin scroll housing. If you want to run 1 gate you divide each bank as seen in the picture. That way the exhaust pulses don’t interfere with each other.

 

Thats cool, just never seen it. I know that 1K header I had on my old Ford 2.3 didn't have one, and neither did my DSM, but it certainly makes sense. I think it's funny how much I miss the old little pocket rocket cars I had. Certainly my old Dodge Shelby. LOL

 

So is there any advice on how long the 3" pipe can be between the merge and the flange? Only reason I am asking is that I am running a single wideband sensor so if I can merge the pipes close to the engine then I can put the sensor in the 3" pipe and read the average of both banks. Also it would be easier to run a single pipe to the rear vs a dual setup.

 

Closer the merge is to the turbo the better it may be. Hard to say without images and more details. Just merge it where it makes sense the most with the space you have.

As far as your wideband, you will need to put it AFTER the turbo. Pre-turbo will not work for 2 reasons....1) You need pressure compensation to get an accurate reading. Unless you plan on a pressure transducer with a long standoff to drop temperature at the pressure transducer so it doesnt fail and a non symmetrical scaling function whether your rich or lean, then heres your first reason not to do it 2) Some have reported premature failures of the sensors when exposed to the high temperatures pre-turbo. If you read the maximum temperature and pressure recommendations for a Bosch LSU 4.9 in its specification sheet, If I recall pre-turbo is very close if not exceeding the limits so it would make sense that they could fail. Save yourself all of the headaches and just go a few feet AFTER the turbo in the downpipe.

1 way to do it pre-turbo is build a chamber for it and flow a small amount of gas out of the exhaust (use a flow orifice) into the chamber where it reads and then dump that exhaust sample into a lower pressure location (i.e. to ambient air or back into the downpipe). These systems are kind of dumb in my opinion and i would just resort to EGT per cylinder and/or reading spark plugs if you can only monitor 1 sensor for all 8 cylinders.

 

Why didnt you ask the fab guy these questions?

 

How much power are you trying to make?

What will it weigh?

What will be the bottom ET and Max MPH your shooting for?

 

Sorry for not responding, had a busy couple weeks.

Didn't ask the fab guys because I wasn't thinking about this when I spoke to them. I just wanted the flange to start mocking stuff up. I was there 2 weeks before I thought about it. And the fab guys aren't at the main shop, they have a separate building that's not open to the public just to walk in or call them. Everything goes through the main store. If you would like to help, please do, Its appreciated.

Plus I trust "some" of the guys on this site for actual knowledge and real help.

For the ones that only want to pop in and make smart *** remarks, don't.

Phil, Its a SBE 6.0 going for all I can get out of it. Maybe 1000 rwhp is the end goal. There are some things that have to be changed to achieve this number. Right now I am getting it together to get it going and learn turbos and tuning. If my design doesn't work for the 1000 then I will most likely have a pipe setup built by someone that knows more than I do. The weight is unknown but it was 3250 with me in it before the cage and turbo parts. Its A2W as well. Meth injection on race gas. After removing what I could on the interior and under the hood I would be happy at 3300 lbs. I do not have an ET I am going for, just as fast as I can get it go. I want to race in some no prep and grudge races.

Now for a little update. I finally got to work on it this weekend to get some of the piping done. I ended up using the shorty headers since I had them and the tube sizing is good for my setup. I cut off the 3 bolt flange and welded on a V-band flange to make it easier and get rid of the gasket. Ran 2.25" pipe and have gotten to what the picture shows. Stopping there until I figure out the flange.



Worked on the flanges today and have several options. I am posting pictures for input on what will work best, keeping in mind I am wanting to run 1 wastegate.

I have 1 divided flange and 1 open flange. So I have options.

First, when I formed the 3" pipe its too small for the flange opening. So I modified the pipe to open it up to fit in the flange. Will need some cleaning up and filler pieces but it easily allows me to run a single WG.




Next, I formed a couple of 2.25" pipes. The do not fit "inside" the divided flange. I can weld these to the outside of the flange. I know this is the common way. But its 2 separate pipes and will need 2 WG inlet pipes merged into the 1 WG.




Finally I can install the 2 2.25" pipes inside the open flange and plug up the open areas in the picture. This will still be like a divided setup but again will still need 2 separate pipes to the WG.