I have a lbz with a built motor. .020 Mahle pistons, The heads have been worked a little, Oversized valves, SoCal 3388 cam, ats pulse flow manifolds and up pipes, 25 lpm ddp injectors. The turbo is the htt 371 with the t4 .91 exhaust housing. It surges real bad from 1700 to 2250 rpm when it's making 10-20 lbs of boost. What could cause it to do this. And what would be the fix. I have a dsp 5 and it does it on all tunes. So I don't think it's tuning related. It really sucks because when I'm going 70 mph it has to be in 4th gear up any little hill or it surges.
Htt s371 surging
- Thread starter Jackmo
- Start date
What size is the turbine wheel since it is an s300? If the turbine wheel and compressor are close in size, the turbo can sometimes have surging Iissue's.
I don't know how to explain surging very well. It's kind of a barking sound. The wheel is stalling out because the turbo is pushing more air than what the engine needs.
It kinda sounds like the turbine is too close in size to the compressor wheel. Possibly a bigger turbine wheel?
Not sure what the op has going on here but judging by what the op posted about the issue is not when towing however it could be worse if the op were to try towing Subd as I'm interested to hear what the problem is having a set of wheels that close to each other almost sounds like egts would be high as well
I talked to him he says its probably due to the head and cam work need to step up to a s4 turbo. this turbo has done 800 hp on built truck before though and has done very well on some 6.0s with fueling and motor work. never herd of anyone having surging issues with it have you tried checking it for play in the shaft?
You said shaft!! :rofl::rofl::roflmao:
I would talk with HTT and then look at tuning.
Yellowchevy
Have had awesome success with that turbo without many complaints. I'd guess the increased flow from a better cam and the head work have something to do with this. Could be gearing and elevation related as well. I'd bet moving to an s400 frame with a larger turbine is going to be your best answer.
That 371 has done 807 without surge issues in an lb7, but it was stock heads and cam.
That 371 has done 807 without surge issues in an lb7, but it was stock heads and cam.
It does it wether I'm towing or not. It was a new turbo when I put it in and it has done it since day one. My tune #1 is 1300 us and the Egts are 1200*. #5 is 2500us with the Egts being 1850*. That seems high to me but I'm not real sure with the power it's making. I haven't dynoed it but I'm guessing 750+ hp. I called htt. I can't remember if it was jake I talked to but he said it has never been an issue before with this turbo. Is it possible that the exhaust side of the engine flows better than the intake side and make it do this?
It sounds like you have too much fuel to drive it. If you put a blow off in the system you will prevent damage. Without it and you will rebuild it often. On stock fuel it is great. With 100 overs it would surge but was preventable with careful driving habits. Problem is a combination of things going on.