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Discussion Starter #1
I’ve been reading through all the threads on compound turbos, but hoping to hear feedback on your setups. Especially interested to hear towing performance.

I’m looking at an S400 over the stock turbo and don’t need to exceed 700hp. It seems the S475 is the most popular choice. I’m wondering how happy people have been with that turbo choice. Do you notice lag with the spool of the 475 as it starts to feed the 351?? Does it seem to drop out with shifts? Do you think the 472 would have been a better fit??

Despite most of my driving being unloaded, I’m looking to make improvements for towing a 12k 5th wheel. The majority of the hauls are freeway but it’s the last handful of miles are the worst. This is typically when it turns to windy mountainous roads and a grand finale of long steep slow climbs with the pedal to the floor in to maintain forward movement. As you would expect EGT, coolant and trans temps are to the limits.

Maybe I’m thinking too much about this and have paralysis of analysis. Either way your feedback is appreciated.
 

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I have a s475/stock setup from DPS, great pulling power and easy to daily drive. Even with 100hp injectors EGT’s stay in check rarely touching 1100. I’m not sure how much difference a 472 would have made, boost comes in pretty quick.
 

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he351 with gate port drilled to 1.0" will help relieve back pressure.

The s475/1.15AR is the better choice for spool up. We have switched a few people to the 1.15AR from the 1.32AR for towing and daily driving applicaitons when they has a 57mm-62mm and they have been quite happy with the faster response. I think its worth the extra $250 or so to have the faster spool up.
 

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Discussion Starter #4
Thanks!
I intend to drill the waste gate and agree it’s money well spent for the tighter AR turbine housing. I hadn’t even consider the 1.32 as an option.

In my searching I’ve been contemplating the S472 and S475 but did not catch the differences that the 472 is an SX-E with a T-4 housing vs the more standard S475SX with T-6 housing.

Sorry for the confusion.
 

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there is 171701 Which is 71.1mm that people commonly refer to as a 72mm 171702 is 74,56mm and people call a 75mm

Then there is the SXE 72mm which is more efficient than the s475 and flows a little bit more. It has an 87.1mm turbine wheel. Trouble is it only comes in a T4 so it may limit the turbine housing options. The BD kit uses the T4 SXE for their piping kit. But they also use an s300 for the little turbo.

Which way are you leaning?
 

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Discussion Starter #6
I’m not leaning one way or the other yet. As much as I’d like to make gobs of power, I have to be realistic and should expect to tow under 500hp. There are a few variables to work out and consider.

I still have stock fuel and no tuning. With 225k and an occasional rougher idle, I’m looking at new injectors. If I’m spending the $$ I might as well go a little over right??

I didn’t expect to run more than 400hp, but with more fuel and tuning it’s not unrealistic to exceed. Now looking at the compounds, I question if I should make a few more upgrades to hold beyond 600hp while it’s on the stand.

I need to check for exhaust manifold cracks and the turbo health. If both are not good for another 250k, then I will weigh the manifold/turbo/kit vs a complete s300/s400 kit.
 

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I’m hoping you go with the 472sxe like in the PDD kit and let us know how it is. I’ve been looking at the same type of kits and looks like the 472sxe will flow more and spool faster than the older s475 but at several hundred dollars more. Curious to know if it’s worth it.


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Definitely go for the 1.15AR. My compounds were 1.32AR S475 with an HE351 with the wastegate drilled out. While I removed the compounds for other reasons, I know you've read my comments on the VGT thread where my driving habits and fueling had me not normally in the operating region for the primary and it affected performance. Bigger isn't always better.

I wish ATS still made their old add a turbo compounds with an A5000, it has a 71mm compressor, 83mm turbine with a 0.90AR housing. They had a cast hot pipe that oriented the A5000 in the same location as the HE351. This comment isn't so much about the turbo choice but packaging, I know you still can get the A5000 that way.
 
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I love my stock/475 combo. It gets me to about 700hp, and the truck tows like a champ. MPI made my setup.
 

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I'm very happy with my stocker S475 setup. I don't think there would have been much of a noticeable difference if I went with an S472. I do have a manual and I don't have an issue with spool up after a shift. How early or late (RPM wise) I shift will make a difference in how fast the turbos spool back up.

I don't tow very often at all and when I do, never much weight. A few years back when I moved, i rolled over a scale with the loaded trailer. I weighed 19,500 lbs. There is a windy mountain hill i had to go up, around 7 miles long. It's a fairly steep grade but I pulled it doing 70 MPH in my top performance tune. I'd slow down for the corners and then hammer down till I got up to 70 again. My EGTs never 1500 or 1600°, I can't remember which one and my ECT hit around 237°, but I also had the fan clutch unplugged.

Tuning is going to play a big role in how well a compound set performs. So make sure you get quality custom tuning if you get compounds.
 
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Discussion Starter #11
“DaveB.inVa” said:
Definitely go for the 1.15AR. My compounds were 1.32AR S475 with an HE351 with the wastegate drilled out.
I did read your responses in the VGT thread but I didn’t realize you were running the 1.32. That’s actually what started me questioning if compounds would still be an option but seeing it’s truly driving habits vs sizing mismatch gives me more confidence.

GRUNT 11B said:
I do have a manual and I don't have an issue with spool up after a shift. How early or late (RPM wise) I shift will make a difference in how fast the turbos spool back up.
Thanks! I was hoping you’d comment about that. It’s basically my main question/concern. Having to get out of the gas, loose the primary spool and then back in. If you could imagine it as a dyno plot, I was wondering if it would show somewhat of a power dip while the primary recovers.

“Kmehr” said:
I’m hoping you go with the 472sxe like in the PDD kit and let us know how it is.
I’d love to see back-to-back testing of the two types of kits.
 

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You will lose some boost when shifting, but how fast it comes back will depend on your RPMs. Tuning will also play a big role.
 
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