Soft bottom end power om617 - Page 4 - PeachParts Mercedes-Benz Forum

vwnate1 · #46 12-24-2019, 09:46 PM

Good to hear you made some progress ! .

Some here will never grasp / accept that each machine is slightly different and so will respond differently to each thing you try .

rwd4evr · #47 01-03-2020, 03:05 PM

So how bad is it to run no waste gate line and like 16-17 psi of boost? I'm fairly certain it was running like that before I ever put a boost gauge in it. I know for sure the fuel and running it on is less potent than diesel at this point. I really wish I had a pyrometer on here but I just haven't gotten around to doing it. I've messed around with dissconnecting it, definitely seems to pull harder and smoke less. Everything I've read seems to say that you don't hurt a diesel with too much air you hurt it with too much fuel. People are running larger turbos and higher boost so is anything I'm missing bad for it that way? I'm not going to floor it up a hill for 5 minutes towing it anything like that.

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Diseasel300 · #48 01-03-2020, 03:47 PM

My 350SD had a blown diaphragm in the waste gate actuator when I got it and had been that way a LONG time. Someone in the past had long ago deleted the overboost valve, so it was like deleting the ALDA and raising boost pressure.

Other than a LOT more turbo noise (think Peterbilt), the car isn't any faster, doesn't accelerate any differently, and made no noticeable power improvement with the turbo making as much boost as possible. Considering it's a rod-bender engine and it's just fine, I'd suspect it isn't a problem, but you shouldn't expect any sort of magic improvement. I repaired mine and haven't looked back.

rwd4evr · #49 01-03-2020, 03:57 PM

I'll have to do a standing start test on the same flat ground back to back. It certainly feels better but the alda delete did make a big difference in its performance. So maybe it's all just feeling better.

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Jarod · #50 01-03-2020, 05:20 PM

About the only major risk is overspeeding the turbo and it blowing chunks of compressor wheel into your intake. But EGTs are a secondary concern.

Turbos have a efficiency map, and there is a point where they are making the air so hot it hurts performance because you might be blowing 200+ degree air into the intake, but with our cars not having any form of IAT sensor that does any real useful function you'll just raise EGTS above a certain boost level.

Not having any form of intercooling or WMI exacerbates this problem on our cars.

I'm unsure of what the map looks like on the t3 or kkk but I know the kkk chokes out airflow long before the engine is done winding up with or without wastegate.

I know the HX35s on my trucks are good to 35psi (stock is around 20psi) and then they tend to get very prone to failure very quickly, as in sometimes a turbo only lasting a few thousand miles before it explodes if you try to run it at 35 or above.

I've turned up 617s to around 12 psi, as 8-10 is stock from what I recall, on some cars the gate springs were so weak they barely made 6psi.

I'd love to find a VGT turbo, or even a more modern design conventional turbo that would fit fairly easily on the manifolds, but time/money vs benefit I'm not pursuing it very seriously.

Jarod · #51 01-03-2020, 05:27 PM

Now do also keep in mind that extra boost does no good without the fuel to back it up.

You'd need to crack the pump open and turn the full load up to compensate for the extra boost to get any benefit, as the alda doesn't change the maximum fuel delivered, that is internal via the rack limiter.

If you're wanting to get into that kind of performance tuning I'd highly suggest making sure every other part of the engine is healthy before then, timing chain, head gasket, injectors (go a size up, set pop a hair higher, maybe 100psi or so and advance IP timing a few degrees to compensate for the extra pressure)

I'm no expert on all this, just what I've learned from my own stuff, and reading others experiences, my work keeps me 99% on gasoline engines.

hercules · #52 01-04-2020, 09:42 PM

Quote:

Originally Posted by Jarod

Now do also keep in mind that extra boost does no good without the fuel to back it up.

Agreed,but higher volume of air sooner makes a big difference.
Just installed a 60ar compressor 48ar turbine turbo,light throttle 5lbs of boost
in one second, drives totally different. Higher speeds are also improved.
No extra fuel was given,200 thousand on engine. Six lbs boost cruise at
60 mph.

rwd4evr · #53 01-04-2020, 10:26 PM

It's about 10 psi with wastegate line hooked up. Without it's getting up to and I think just barely pinning the gauge I have hooked up at 17psi. It's smoking far less at full throttle which would make sense. I'd say it does feel a bit stronger, like not nosing over, up over 3500 or so. I'm kinda confused because it just started running great again after towing a basically empty(not even 1000#) trailer one night, it felt really weak, full throttle to keep it going 55-60. I popped the wastegate line off to see if it made a difference when almost home. Didn't really notice much. The next day I refueled from the same batch that was in it and it all the sudden had that initial power from almost no boost back and was pulling harder than it had in quite awhile, since the alda started failing at least. But in that whole ordeal I found the cracked wastegate line and fixed it, removed the EGR also and removed the failed ALDA. It has been better since the alda removal but not like it is now. Curiously the engine is a little noisier again, after I started fuel experiments it lost some clattery noises and stopped nailing completely (still not nailing). I'm wondering if it had some carbon buildup that I cooked off towing? Or it just saw that om603 powered car getting some attention and decided to start acting right!

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Jarod · #54 01-06-2020, 01:37 PM

Quote:

Originally Posted by hercules

Agreed,but higher volume of air sooner makes a big difference.
Just installed a 60ar compressor 48ar turbine turbo,light throttle 5lbs of boost
in one second, drives totally different. Higher speeds are also improved.
No extra fuel was given,200 thousand on engine. Six lbs boost cruise at
60 mph.

No doubt, getting boost faster allows better use of the available fuel, and the turbos that came on our cars are ancient tech by todays standards.
Being able to flow more air and spool faster will burn the fuel you have more efficiently, and adding more fuel then becomes doable without going all brodozer bombing around town.

What all did you have to do to fit up that turbo? And what more info about which turbo and flange etc needed might you be willing to share?

I've been pondering an upgrade of some kind but don't want to kill the daily drivability of the car with something that takes forever to spool, I'd prefer finding a vgt or ball bearing turbo that'll light super fast but not choke out the top end.

There is so many options out there for my trucks but very little for the 617s it seems.

I've looked into various options from TDIs as well as sprinters and such but haven't found what seems like an ideal solution.

rwd4evr · #55 01-11-2020, 08:04 PM

Here's another bizarre twist to everything happening at once(well over the course of a couple weeks I guess when it started.) After alda removal it seemed pretty good, maybe down on power a little but I thought it was my diesel brew. After I towed with the car last week(with very little power),I didn't do anything to it and the next day it was running great. I figured it cooked off some carbon in the exhaust or shook a sticky injector loose or something from full throttle on the highway at 55-60 in 3rd gear. It's been running great. Last night I started loosing power slowly over the course of a couple hours delivering pizza. Then I noticed the pedal felt odd and not very springy. I started poking around and found that the slotted adjustment on the first part of the twisting throttle linkage had come loose and slipped to the least possible amount of travel. I adjusted it to the most possible and tightened it up and the pedal felt completely different than it ever has and the car has more power even than it did for the last few days. So I'm guessing it slowly was slipping when the alda started failing. It must have been at the point of loose enough to pop back some and stay the other night and give me more throttle again before slipping all the way. All the time I was loosing power I thought it was fuel related. I was trying to figure out how I towed a 2500 lbs trailer with 2 bikes on it this summer when it would barely do 60 woth the same trailer empty.

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