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· Powerstrokeless
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71 Posts
Discussion Starter · #1 ·
How much exhaust flow can the stock internal wastegate on our trucks bypass? I want to build a towing compound set-up, that can be run with hybrids using the stock turbo if possible. the only part I don't have figured out is if I need to use an external gate or if the stock one will be sufficient . I will only be looking for around 400 hp max and plan to tow at around 300. I know I don't really need compounds, but I like doing challenging things and I really love the scream of compounds.
 

· Powerstrokeless
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71 Posts
Discussion Starter · #4 ·
If I have to replace the stock turbo, it will be with an S300 feeding an S400. I can get really good prices on Borg Warner products and I know the combo works well on cummins motors. The big thing is that this will be a very mild set of compounds for towing, not all out power. I believe that the stock turbo can be used as the secondary, I may just try it using the stock gate and add an external later if necessary.
 

· Powerstrokeless
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71 Posts
Discussion Starter · #8 ·
why not get a stock 1.0 A/R housing without the WG and add an external WG?
That is what I will more than likely do if the stock housing will not work for my application. I would just like to show that a good towing set-up can be built relatively cheap using stock components, as opposed to having to pay for both a primary and new secondary turbo.
 

· Caption This
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3,898 Posts
yes, that is what I would like to know.
I've measured them in the past but I can't remember what they are. Seems like they may be 18mm. If no one gives you the info tonight, I'll measure one tomorrow morning and let you know.
 

· Powerstrokeless
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71 Posts
Discussion Starter · #10 ·
Thanks, I am just wondering if I can keep the stocker limited to about 20 lbs. using that small of a gate or If I will have to use one in the 30 mm range. I am sure I don't need a 44mm like Charles is using, but I am not sure if 18-20 will be enough. Either way this is just going to be a spare time project for me and I still have a lot of fitment and planning to do before I start.
 

· Registered
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319 Posts
The stock housing is a .84 housing. The .84 has nothing to do with the wheel. I'm with Mike on this one. Get an external gate. Should be able to run it with the stock turbo but if you don't have a big enough gate you'll pop the turbo. Get drive and boost pressure gauges between the stages as well so that you can tune the set up. You want both turbos operating at as close to the same PR as possible for maximum efficiency. And I wouldn't just throw a turbo on because someone else has it on a completely different engine and it works OK. A cummins is 1.4 litres smaller therefore it's turbo needs are different. Do some research and read some maps and find two that will work well together at the boost levels you are looking for.
 

· Banned
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7,730 Posts
Here's what I have found....

The answer to your issue depends heavily on whether or not you plan to intercool the second stage, or run it into the engine directly as I have.

If you do plan to intercool stage 2:

Then yes, I believe the stock integral wastegate is adequate to hold the charger to 20lbs. Or at least the 1.0 housing on the BB would have done it with it's integral gate. The stocker with the .84 housing might be a little dicey, but I think it will work (Good enough to save you the time, money and trouble of adding an EXT gate) Then you can run around 20lbs per stage and be all happy.

If you do not plan to intercool stage 2:

Then no. This is the biggest reason......my 44mm gate is TOO SMALL right now..... :eek: If you don't intercool the second stage you will not want to balance the stages. You will want to run absolutely as much pressure on the first stage (intercooled) as you possibly can. And that means that the second stage will be doing as little as possible (lowest intake air temp). Right now I run about 25-27lbs on the 47 and about 7-10lbs on the 38R when at full boost. Now on the bottom the 38R might make as much as 30lbs alone, but once the 47 starts coming online it takes over and the egts actually start dropping as the power starts coming up.

I have actually removed material from the end of the valvestem on the Tial gate to allow more lift, and also cut about an inch from the lowest rate of the large diameter springs they offer in order to ensure that it is absolutely bottomed out open when I'm up on boost. I wish I could hold that charger down to 4lbs or so. Then I could run upward of 30 on the 47 without popping the manifold.

The other issue is, what manifold boost are you looking for? If I were running say 60lbs instead of 50, that same 44mm gate would all the sudden be more than enough. But at 50, it's asking a lot of it to keep that 38R settled down.

Just my experience with it.

Good Luck.
 

· Caption This
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3,898 Posts
yes, that is what I would like to know.
The wastegate hole in the .84 housing I have measures .720" dia. The wafer that covers it measures 1.2". The hole isn't centered on the wafer but it appears to have a little growing room.
 

· Powerstrokeless
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71 Posts
Discussion Starter · #17 ·
I think the easiest way to set it up will be not cooling the second stage, at least if I try to put the bigger turbo where the passenger battery is. I would rather fab up an external gate than mess with trying to cool the second stage. I don't think I will be looking for much more than 40-45 lbs. of boost. I like the idea of getting moving on the secondary, and then bypassing it almost completely to run on the primary so that is what I will probably do.
 

· Powerstrokeless
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71 Posts
Discussion Starter · #18 ·
And I wouldn't just throw a turbo on because someone else has it on a completely different engine and it works OK. A cummins is 1.4 litres smaller therefore it's turbo needs are different. Do some research and read some maps and find two that will work well together at the boost levels you are looking for.

I am not throwing a turbo on, I can configure an S400, or 300 if necesary, to work well with just about any secondary turbo out there. That is the great thing about the 400, it can be just had in many different sizes and trims and that gives you a wide array of maps to choose from and match with the secondary. I am perfectly confident that an S300 and 400 setup would work on my truck I would just like to avoid buying two turbos if I can use my stocker.
 
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