38r to sxe

The Brad · Sep 21, 2017

There are only 2 kits that I know of, Irate Diesel and Carson Stauffer Diesel.

KCTurbos · Sep 21, 2017

The Brad said:
I don't think anyone is trying to tow at 1500 rpm, but the ability to do so is indicative of how manageable the EGTs will be at more appropriate towing rpm. My setup with the 38r made good power up top, but I had to keep it at 2500+rpm to keep the EGTs at 1200 while towing 10k which often forced me to 2nd gear over 3k rpm on a 6% grade. Many turbo reviews are subjective since most can only compare to what they know. Knowing what I know now, the best all around DD/towing turbo will spool early, not surge and still flow well up top, both on the compressor and exhaust side. So, IMHO, the vids showing low rpm/high boost are as valid as a wot pull while showing MAP vs. EBP. 1200 degrees doesn't scare me at all, and wouldn't expect to make much power under 2k.

mikeeg02 said:
The only reason I have videos showing boost at 1,500 rpms is to show how early boost can come on, because every one has a different opinion of when a turbo "spools up". I prefer to tow in OD on the highway, usually around 1,800-2,000 rpms and when rolling through hills prefer to lug it up but will shift if necessary. Not wanting to make a smoke show or slow down. I did a lot of research to match my turbo to my fuel, spent hours plotting on compressor maps, gave up after trying to read turbine maps and with a little bit of luck got it right.

That being said, I'm not sure I understand someone complaining about 1,200 degree egt readings. It sounds like they need to understand with a turbo sized to make good power on the big end, you need more heat on the small end to make the turbo work, as turbos work off of airflow (rpm) and heat. Less of one, requires more of the other. (And I know that you know all that) The point I'm trying to make is it sounds like your customer needs more education on how a turbo works. Plus at 10,000' he needs every advantage he can get, whether it be to slow down, increase rpm, or just stay home. LOL just kidding.

With my setup, sub 2,000 rpm I can make up the difference in lack of rpm with heat, but it won't push above 1,200-1,250 degrees in my second hottest file while towing, keeping things pretty smoke free. Im sure with someone elses tuning you could over fuel down low but I'm not trying to break anything.

Thanks for the replies. I agree 100%. Hope I did not muck up your thread.

ja_cain · Sep 21, 2017

Good stuff. The current version of the KC 38r looks to have a copy of the 366sxe compressor wheel and also the 74mm turbine wheel. Plus, dual bb instead of journal bearings. I woukd look into one of those first before going t4 with a 366sxe.

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mikeeg02 · Sep 21, 2017

lariat 7.3 said:
following. Im ready to dump my 38R with mods in the sig what would you all recommend? Main focus is DD and being able to tow in OD. Rarely run it down the strip but would still like to retain some power up top

Where do you want to tow? IE what rpm? With 35s, and 3.73s at the same speeds I tow at, I would probably go for the 364.5, 74mm with a 1.0. I usually tow between 60-70. Usually not over 65mph. I dont have any issue, but I have ~31" tires and 3.73s. (235/85-16s, DRW) At 70mph Im at about 2050 IIRC. If you tow in the same speed range as I do, you may find you're still needing to downshift a little more. If you tow faster than I, it may not be an issue. But if your primary goal is towing and DD, the 364.5 may be a better fit.(Trust me, it will still pull hard on top) The Brad has 35s IIRC and a 364.5 and even has a .9 housing and says it tows like a dream.

Though I wouldnt change anything on my setup. I dont need to watch at my gauges ever.

KCTurbos said:
Thanks for the replies. I agree 100%. Hope I did not muck up your thread.

You're good, its nice to hear from our manufacturers too. Whether its complaints from some of their customers or not. I think it helps everyone understand better what people are trying to accomplish.

lariat 7.3 · Sep 21, 2017

mikeeg02 said:
Where do you want to tow? IE what rpm? With 35s, and 3.73s at the same speeds I tow at, I would probably go for the 364.5, 74mm with a 1.0. I usually tow between 60-70. Usually not over 65mph. I dont have any issue, but I have ~31" tires and 3.73s. (235/85-16s, DRW) At 70mph Im at about 2050 IIRC. If you tow in the same speed range as I do, you may find you're still needing to downshift a little more. If you tow faster than I, it may not be an issue. But if your primary goal is towing and DD, the 364.5 may be a better fit.(Trust me, it will still pull hard on top) The Brad has 35s IIRC and a 364.5 and even has a .9 housing and says it tows like a dream.

Though I wouldnt change anything on my setup. I dont need to watch at my gauges ever.

I don't tow over 70. I don't even cruise over that. I'm typically 65-70 at 1750-1900 rpms. I'm sick of this thing running so under the turbo. Just took a trip down to the Keys towing a 31 foot 10k boat and run 1000-1200 with the rpms screaming at 60-65

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mikeeg02 · Sep 21, 2017

Going off what you just said, I would definitely 364.5, 74mm, 1.0. Myself, The Brad, and others have Carson Stauffers kit. I think its pretty nice. If I was looking for a truck that could DD, sled pull, and drag race I would probably get the IRATE kit because you can get an external gate plumbed in. But I'm not, and Carson's kit is what I have. He is also a great guy to deal with. If you get a chance to talk with him, you will enjoy it. Very knowledgeable guy.

lariat 7.3 · Sep 21, 2017

Is the external gate necessary to keep the BP in check in the upper rpms? Or will the 1.0 be ok

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mikeeg02 · Sep 21, 2017

With my setup and the tuning figured out, I see a max boost / backpressure of 42-65psi. No reason for a gate, still in the safe zone.

lariat 7.3 · Sep 21, 2017

I see. Isn't the irate kit like another grand?

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mikeeg02 · Sep 21, 2017

With a gate I think it is, without I think its a couple hundred more. Haven't looked in a while. I have spoken with them, and they are also very knowledgeable people, I dont mean to take anything from them. I ended up going with Carson's for several reasons, he's local, and I have done a lot of business with him over the years.

lariat 7.3 · Sep 21, 2017

i gotcha

mikeeg02 · Sep 21, 2017

It also cannot hurt to call and talk with both vendors. I would bet Carson would push either the 364.5 or 366, both with 1.0. (he's the one that sold me on the exhaust housing)

CarportMechanic · Sep 21, 2017

mikeeg02 said:
It also cannot hurt to call and talk with both vendors. I would bet Carson would push either the 364.5 or 366, both with 1.0. (he's the one that sold me on the exhaust housing)

Are you an Auto or manual? Sorry if I missed that.

Curious why he recommended the 1.0 vs the .91, did he explain?

mikeeg02 · Sep 21, 2017

Im a manual. Carson told me he likes free flowing on the exhaust side. Run as loose a housing as possible while retaining spool up and boost. Mine is no slouch in spool up. I guess I can populate my sig some.

Bmcgarvie · Sep 21, 2017

Just to clarify I'm definitely not towing at 1500 rpm. I'm just trying to hear everyone's experiences with different sxe turbos. My biggest complaint is that with the 38r I'm usually under the turbo when just cruising along just looking to clean up a little bit of smoke on throttle tip in. The 38r does pretty good but only after 2000 rpm. I'd just like a little more meat below then. Not that I tow there just sometimes get caught between gears.

hucorey · Sep 23, 2017

175/80's are more oil hungry than 200/80's as the 200's are hybrids.

I'm running the updated KC38R, which is the nearly identical as the s366sxe but ball bearing, along with PIS 230/100's. I never had and egt issues even towing 8-9k through Northern Michigan in my hot race tune (LOL).

I am changing to 4:10 gears because sometimes I do tow 12k and would rpms a bit higher when I'm in the 55-60mph range. 3:73 towing heavy in OD just doesn't cut it with larger than stock tires.

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ja_cain · Sep 23, 2017

hucorey said:
175/80's are more oil hungry than 200/80's as the 200's are hybrids.

I'm running the updated KC38R, which is the nearly identical as the s366sxe but ball bearing, along with PIS 230/100's. I never had and egt issues even towing 8-9k through Northern Michigan in my hot race tune (LOL).

I am changing to 4:10 gears because sometimes I do tow 12k and would rpms a bit higher when I'm in the 55-60mph range. 3:73 towing heavy in OD just doesn't cut it with larger than stock tires.

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Awesome! 200/80's are what I'm going with when it's time for injectors on my rig. I have a zf6 and 33's and think the updated KC38R would be sweet. A 364.5 version would be awesome to try too. This is why I haven't pulled the trigger on a turbo yet as I'm holding out for a version like this.

freddie · Sep 25, 2017

hucorey said:
I am changing to 4:10 gears because sometimes I do tow 12k and would rpms a bit higher when I'm in the 55-60mph range. 3:73 towing heavy in OD just doesn't cut it with larger than stock tires.

Good to know. Anxious to see how my truck will tow with the BASB and 35s with 3.55's. Thinking a regear will be in my future, just based on the occasional heavy tow.

MeTo · Sep 25, 2017

For the people thinking about regearing. If you don't want gear noise; you will have to buy OEM gears. I learned that the hard way. Essentially, OEM gears are hobbed, aftermarket are cut. That is why they are cheaper. I have not found an aftermarket ring and pinon set that is hobbed. In the end, I had the rearend Sterling gears "set" to have the whine on deceleration. The Dana 60 OEM gears in front are silent.

After 1.5 years, I'm still looking for a good set of 3.55s for a 10.25 Sterling.

If anyone is interested in some low millage OEM 4.10s (Dana 60 & Sterling 10.25) I have some cheap.

mikeeg02 · Sep 25, 2017

hucorey said:
175/80's are more oil hungry than 200/80's as the 200's are hybrids.

I'm running the updated KC38R, which is the nearly identical as the s366sxe but ball bearing, along with PIS 230/100's. I never had and egt issues even towing 8-9k through Northern Michigan in my hot race tune (LOL).

I am changing to 4:10 gears because sometimes I do tow 12k and would rpms a bit higher when I'm in the 55-60mph range. 3:73 towing heavy in OD just doesn't cut it with larger than stock tires.

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Or you could just put the right turbo on to tow at that rpm, downshift a gear, or put the stock tires back on. The last being the cheapest solution because you'll need tires at some point anyways. But That's my opinion. I can't imagine taking away highway rpms from a truck like that with only 35" tires.

Also, and I don't mean to take anything from the guys at KC, because I think it's great they are still innovating for our old platform. But saying a kc38r is nearly identical to a 366sxe may be a bit of a stretch.

Since you have it, how much boost can you make at 1500 rpms? Can you do it smoke free ?

This is not to be taken as a jab either. From the reports I've seen, the kc38r has been a solid performer when compared to the garret 38r.