LMM: S371 to S475 conversion.

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Dragbear

Dragbear
Aug 4, 2013
36
0
6
Hi my name is Rick Abare.
I have a LMM daily driver that i pull 2.5 workstok in.
I ran a S371/ 83/ .91 all last year with no issues. I wanted to upgrade to the S400s for this year and my son has a
S475 / 91 / .90 so I bought a S400 install kit from HSP and bolted it on.
What a PIG!!!! What a nightmare to drive!!
No power below 2500rpm just a lot of smoke. I have to run 4th gear 80mph to keep it above 2500 to get up any hills.
Wear am I going wrong??? This turbo came off my son's 5.9 Cummins and made 70psi of boost. He was putting 50' on me at the pulls!
My set up is:
Built bottom end 15.8 comp.
Alt fire cam.
150% injectors
Twin CP3s
Fass
Pro fab headers and up pipes
T4 pedestal
Thanks for any help!!
I am about to abort this s400 nightmare!!!
 
torqued2dmax

torqued2dmax

Member
Mar 26, 2017
646
1
18
Brookville, PA
Auto or stick ? What tuning system ? What gears ? So are you not going to pull work stock anymore ? Someone with alot more knowledge than me might let us know if you need to change to a T6 pedestal ! Good luck!
 
ikeG

ikeG

Oughta Know Better
Apr 19, 2011
2,472
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Western PA
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If it actually is the 92mm turbine, it is the laziest turbine you could of chosen. The 3 common Borg warner turbines are 83/74, 87/80, & 96/88. They also made a 92/82 that flows less than the smaller wheels and also manages to be super lazy.
 
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Dragbear

Dragbear
Aug 4, 2013
36
0
6
At this point the converter is out of the pitcher because I am on the road over 45mph and the converter is locked. If I can't get it to work work better here there is no reason to go any further.

I had issues with the mass air reading going to 0 a lot so Danville tuned the mass air out of the tuning. It reads 600 all the time now. It has been that way for 2 years and runs great.
I have tuning from Starlight also and he uses the mass air and it runs no better than Danvilles tune.
The mass air goes to 0 above 3000rpm. I have replaced it and it no longer goes to 0.

Still running stock gears with a built Allison Trany. I had to get the torque converter restalled for the S371 and could foot brake it to 2200rpm and 20psi of boost. With this S475 the best I can get is 1800 and 1psi of boost.

I am thinking that I need to get rid of the 91mm turbine and get an 83mm??
Thanks, Rick Abare
 
D

Dragbear

Dragbear
Aug 4, 2013
36
0
6
I didn't buy this turbo it is a spare from my son's dodge truck. It is a 2.5 pulling turbo from Tator. I just wanted to try it before I bought one.

I am still running 2.5 work stock in some places and 2.6 in others. Most places require you to have a stock turbo so i get forced into the 2.6 class a lot.
 
DAVe3283

DAVe3283

Heavy & Slow
Sep 3, 2009
3,732
302
83
Boise, ID, USA
You need to play with your transmission tune. You keep saying the converter is locked missing what we are all implying: it shouldn't be.

My truck is tuned to unlock the converter as soon as it starts to lug. That lets the RPM come up so it gets some boost, then it locks again.

And it does sound like your converter is too tight too, if you can't build boost on the line. I was in basically your situation with my cam+turbo combo, and I solved it with a re-stall and tuning (both engine and transmission tunes).

Sent from my Cat S60 using Tapatalk
 
quinton

quinton

Active member
Nov 28, 2011
1,883
0
36
Granbury Tx.
dAVe3283 is correct. Convertor and tuning will fix it. Ran a few different s475’s and each one I had to adjust tuning every time, convertor restalled made a world of difference too. You don’t want the convertor locked that low of speed with that turbo setup. These guys telling you answers, like Ne-max, more than likely have been through the same scenario and already have done the trial and error.
 
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Dragbear

Dragbear
Aug 4, 2013
36
0
6
Thanks for all the information. I do realize the stall will need to be changed to be able to launch the truck. I am just not sold on this turbo and I am trying to figure out if I would be a lot happier changing to a smaller turbin before changing the stall. I can unlock the torque manually and see how that works but they build a lot of heat if you run it very long that way.
Thanks, Rick Abare
 
DAVe3283

DAVe3283

Heavy & Slow
Sep 3, 2009
3,732
302
83
Boise, ID, USA
Dragbear said:
Thanks for all the information. I do realize the stall will need to be changed to be able to launch the truck. I am just not sold on this turbo and I am trying to figure out if I would be a lot happier changing to a smaller turbin before changing the stall. I can unlock the torque manually and see how that works but they build a lot of heat if you run it very long that way.
Thanks, Rick Abare
Click to expand...
Just keep an eye on transmission temperatures and get a torque converter with a warranty if you do re-stall. I run up hills all the time in 5th unlocked, and it never overheats. When towing, I usually gear down instead of unlocking, but towing with a big single is going to hurt mileage, so I don't stress.

It is a different animal for sure with a large single. In your case, it is probably cheaper to try a new turbine, but even then you'll probably want a torque converter. That's the rub, you have to commit to the big single life or it won't work for you at all.

Sent from my Cat S60 using Tapatalk
 
D

Dragbear

Dragbear
Aug 4, 2013
36
0
6
Thanks
I went through all this for the last 2 years when I changed from the 63mm cheata vnt to the S371. It ran fairly well until I hooked to the sled and couldn't light the turbo for the first 75'.
Got the torque restalled but it was a bit to high. As soon as I took off it would go to 3900rpm until I locked then it would drop to 1900. Way to much!!!
Had it restalled again and it was perfect. 3600rpm down to 3200 locked.
 
ikeG

ikeG

Oughta Know Better
Apr 19, 2011
2,472
152
63
Western PA
www.facebook.com
Rick, you need to verify if that Borg is indeed the 92mm turbine. They are rare and if you wouldn't have said it, I would have bet a 1000 bucks it wouldn't be that turbine wheel. If it is the 92, there is not a converter in the world that will make you satisfied with street driving that charger. The larger turbine, the 96/88, will actually spool & drive more sensible when fitted in a t4 housing. Sounds like the ideal s400 for you would have the 87/80 turbine wheel.

Sent from my XT1585 using Tapatalk
 
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Dragbear

Dragbear
Aug 4, 2013
36
0
6
The turbo is from Tator and he is putting 91mm turbines in them. I measured it also. It is also in a T4 .90 housing.

It is crazy that it runs so well on my son's Cummins. Normal driving he is pushing 20psi and full out it is over 70.

On mine normal driving is 2psi and maxes out near 40
 
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