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Old 03-02-2020, 10:24 AM   #1
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Boost increase on ISC-350 by adjusting wastegate

Anyone ever adjusted (increased) max boost on an ISC-350 by just adjusting the threaded rod extending from the wastegate air cylinder?

More interested in info from those who have actually DONE it, than opinions from those who have not.
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Old 03-02-2020, 10:39 AM   #2
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Look for posts by IMPRSD, he thinks outside the box, and isn't afraid to try new ideas. For instance he has his ISC churning out over 400HP.
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Old 03-02-2020, 10:51 AM   #3
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Look for posts by IMPRSD, he thinks outside the box, and isn't afraid to try new ideas. For instance he has his ISC churning out over 400HP.
Ray, I've read all his posts, I think. Don't recall him mentioning anything about this. There are "boost foolers" available that simply leak air from the wastegate cylinder so that it cannot move far enough to limit boost as much as in the stock condition. Seems to me that the threaded rod from the wastegate actuator could be adjusted. I'm going to try it. Just wondered if anyone else had done it.

I installed the FASS fuel pump system that IMPRSD did, but for different reasons. I expected absolutely no performance difference from the installation, nor did I get any.
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Old 03-02-2020, 04:33 PM   #4
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Do what you want, waste gate is there for a reason. Too much boost for too long and you start lifting the head off the block. You also create a lean burn, and your pistons end up with melted spots and or holes in them.

Better off to add more fuel. Just remember black smoke is wasted fuel

And any time you play outside the mfg engineered design you should be monitoring EGT.
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Old 03-02-2020, 05:36 PM   #5
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Do what you want, waste gate is there for a reason. Too much boost for too long and you start lifting the head off the block. You also create a lean burn, and your pistons end up with melted spots and or holes in them.

Better off to add more fuel. Just remember black smoke is wasted fuel

And any time you play outside the mfg engineered design you should be monitoring EGT.
Lean burn pertains to spark-ignition gasoline engines. More boost than necessary to burn existing fuel only lowers EGT in diesels. Additional fuel raises EGT. No one ever burned a piston from too much boost...too much fuel, but not too much boost. All modern diesels (20+ years) run with excess air (boost). That is why they do not smoke.

Never heard of a single instance (SUBSTANTIATED, not anonymous undocumented Internet tale) of "head lifted off the block" from too much boost.

This very series of engine and head have been available from Cummins for years with stock boost as high as 32-35 PSI, and HP in excess of 400. My ISC-350 runs about 23 PSI boost. I installed an EGT gage on this coach as well as my previous Cummins-powered coach, which I also "hot-rodded" with no problems whatsoever. I know what my EGT's are, what causes them to rise or fall, and what I need to do to keep them within safe operating limits.

Knowledgeable people with HANDS-ON EXPERIENCE have been improving the performance of diesel engines without problems since before Cummins itself hot-rodded one of its own engines and entered it in the Indy 500 in 1931.

I'm not trying to scorch you, but I did ask for replies from folks with REAL-WORLD EXPERIENCE, not those who parrot what they have read. Misquotes from "Auto Shop 101" don't contribute anything of value to any post.
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Old 03-02-2020, 06:17 PM   #6
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Removed the wastegate assembly today. Like anything exhaust-related on an older diesel, it is always a challenge because of rusty bolts that have been exposed to high temperatures for years.

The wastegate itself, inside the turbo, is free. The wastegate actuator also functions as it should, although I checked it only for operation and not for cracking pressure. So, I think the wastegate function is operating properly.

The actuator has a 1/2" stroke, and the pivot point on the turbo wastegate has very nearly the same stroke.

I'm going to start by limiting the stroke of the actuator. The actuator has a strong spring that holds the wastegate closed. The assemblies are "factory calibrated" and the clevis end is staked to the threaded rod extending from the actuator. The actuator operates by extending its rod when turbo pressure rises to a certain level and overcomes the spring force inside the actuator. I drilled thru the staking on the actuator clevis so I could rotate it on the threaded shaft. I'm going to start by shortening the assembled length by about 1/4" and see how that affects boost pressure. That will prevent the actuator from fully opening the wastegate. I have some obligations at my church the next couple of days, but expect to get it back together and try a test run by Friday. I'll report back then.

BTW, something I've learned in working on a lot of situations where heated/rusted bolts present a challenge is to use an air hammer and a right-angle impact wrench with throttles that will let you "tease" them. Use the air hammer and a blunt-end tool to carefully pound the bolt head. Then use the impact wrench on its lowest power setting and "tease" the throttle to keep it operating at a very low torque setting. You can even use the impact wrench to tighten the bolt with the same low impacts to help loosen it. Sometimes it can take quite a while, but the repeated light impacts will almost always break the bolt loose without breaking it, rounding the bolt head, or damaging the threads. Always use a 6-point socket, of course.
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Old 03-02-2020, 09:04 PM   #7
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Now thatís what I like, someone willing to experiment. When I was checking my waste gate, I thought of doing the same thing. Canít wait to see what you find and if lowers your EGT.

Many years ago, when the Fass fuel pump conversion wasnít common, members like Smitty dared to experiment. Now itís very common.

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Old 03-02-2020, 10:41 PM   #8
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Way to go Vanwill!

There are a lot of Woodchucks out there "chucking wood." ...But at the same time us "out of the box thinkers" need to be restrained sometimes and these naysayers/woodchucks help in these regards. So you woodchucks keep chucking wood... you can count on it... and the rest of us will try to figure out sensible things we can do to improve the performance and MPG of our engines.

I find this thread interesting, because I maybe pulling my turbo this summer and doing an overhaul on it. (TBD)

I have 100,000 miles on my coach and I plan to do an engine inspection as soon as I pull my RV out of storage in May.

So right now I'm just learning about turbo chargers... and I'm finding out that there are a lot of modification "street people" do to their turbos to get more boost (more air flow into their engines).

Consequently, I am keenly interested in my RV turbo and I wonder why I can't find much information about them on IRV2.com?

Vanwill may be on to the least expensive, most reliable, and effective way to increase HP & torque & MPG? TBD.

As for me, I just spent $700 for an Ag Diesel #12100 Power Module (aka "fooler") and now I have 20% more HP (350HP => 420HP). ...So why do I care about getting more HP? ...I don't! ...But I am interest in getting more HP by creating more boost my engine can handle for $0... and I care about lowing my EGTs if that is possible?

Remember what they say: A diesel engine is a "lean burning engine." So if you can add more air... via more boost... then why not do that?

And on the subject of MPG:

What I want to know is why a 38' Monaco at 32,000lbs that is powered by an ISC-350-CAPS is getting 9-9.5 MPG... when my 40' Itasca "Horizon" at 32,000 lbs that is powered by the same engine is only getting 7-7.5 mpg? Is it all aerodynamics or is there a turbo difference involved here?

...But I digress.

I have also read the the Holset HX40W turbo is capable of producing higher turbo boost by just adjusting the actuator rod... just like "Vanwill" wants to do.

This procedure is based making the actuator connecting rod "shorter" so the diaphragm opens the waste gate later... and that will increase boost.

That's sounds easy enough, but does our pre-2004 ISC/ISL turbos have an adjustable actuator connection rod? ...I hope Vanwill can tell us?

And here's a video on a diesel truck that address this adjustment. Of course, this turbo is off a truck, but I think it's applicable to our pre-2004 ISC/ISL turbos. Or so Vanwill tell us soon enough!



My guess is that Vanwill is on to a less expensive way of increasing boost in our Holset 40 turbo. So I will stay tuned to this thread!

In addition, our ISC engine components are the same used in ISL applications that see 30-35" of boost. And these ISL engines are also are rated at 400-450HP, but they do have safety switches built-in to protect from catastrophic failure where our ISC engines do not. And I think the ILS exhaust manifolds are "beefier."

...So while our older ISC motors are under-powered compared to what they can do, that doesn't mean we should "floor it all the time".

This summer I may also add an Aero XL5050 or Jones XL5050 resonator, to replace my muffler. My hope to to reduce EGT. ...However, I would also like to see what Vanwill discovers. And I'm guessing that if that actuator rod is not adjustable, one can always be made or bought that is? TBD

STOCK MP: My MP was always 24" prior to installing the Ag Diesel "fooler" Power Module and then it was 25-25.5" of MP. I chalked this up to more heat... and a faster spinning turbo, but I would have preferred more boost from more air.

That's why I will look into rebuilding my turbo with a "batwing" compressor wheel and some other fine-tuning when the time comes. But more on that later. Right now I want to know if Vanwill discovers he can get more boost out of his turbo by shortening that actuator rod on his turbo?

===

And this is interesting... Back in the day a company called TST Products sold a $200 Turbo Boost "fooler" product that apparently tricked the diaphram into opperating later. This effectively added 5" of boost. Here is the link I found by reading other threads:

https://www.tstproducts.com/83cumminsengines-1.aspx

Is this a viable product? ...I have no idea. Is it worth $200? I have no idea, but they must have sold some. Can you do the same thing by just shortening the rod? I have no idea, but maybe Vanwill can tell us more?

===

Note: The pictures below are for a 2005 ISL turbo with a speed sensor and temperature sensor. ...But frankly, I'm not sure our pre-2004 Holset 40WG turbos (#4025180) with a turbo assembly (#3596079) have a speed sensor or a temperature sensor? I don't think they do, but I have not looked at my turbo yet. This summer I will know more!
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Old 03-02-2020, 11:16 PM   #9
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Lots of the truckers simply pinched off the line to the servo back in the early days of turbo's with waste gates.

Just have to be careful you don't get cavitation happening. It can cause the shaft to snap.

We did lots of little tricks with resistors fooling sensors, etc.

Have fun, but not too much fun. I have seen a number of Cummins engines cook themselves on long climbs after they have been jacked up.

Best to back out and drop a gear if you are climbing a long hill.

Happy Glamping.
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Old 03-03-2020, 02:29 AM   #10
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Maybe this video will bring back memories? ...But if you ever did this, how well did you like the spring actuated waste gate approach?



Here's what some other people said:

* The spring I use has a working range from 12.9 to 30 pounds. Here's the source: https://www.mcmaster.com/9628k58

* The reason for vacuum waste gate is to dump unwanted pressure after you let off throttle.

* I personally hate spring waste gates, because I can never seem to control them properly on compound setups. They either open early allowing a leak (which results in decreased performance) or they open late, which creates "boost creep." However, I also know many people have great results with them!

So this is where I bow out and other people give Vanwill the benefit of your experience. What's the best way to increase boost pressure with a Holset-40WG?

So far I see only three ways to do this:

A) Use a "Boost Fooler" like the one from TST?

B) Modify your vacuum diaphragm arm so it can be adjusted... which presumably is based on travel. I.e., a sorter arm means the waste gate will open more and that that will create more HP, but it also could me the waste-gate will leak prematurely. TBD

C) Take out the vacuum diaphragm altogether... and install an adjustable I-hook (arm) and spring? ...like in the last video.

Now I can't wait to see what Vanwill will come up with?
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Old 03-03-2020, 05:13 PM   #11
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Lean burn pertains to spark-ignition gasoline engines. More boost than necessary to burn existing fuel only lowers EGT in diesels. Additional fuel raises EGT. No one ever burned a piston from too much boost...too much fuel, but not too much boost. All modern diesels (20+ years) run with excess air (boost). That is why they do not smoke.

wrong, more boost than the CAC can handle taking the heat from will raise EGT. It's a heat exchanger designed for your engine and do you know if your peticular turbo can handle more boost without surging? Or are you just gonna see what happens and hope you don't take out the bearings?

Never heard of a single instance (SUBSTANTIATED, not anonymous undocumented Internet tale) of "head lifted off the block" from too much boost.

really, you got to be kidding me. Stretched head bolts and blown head gaskets are common from constant overboosted over fueled engines.

This very series of engine and head have been available from Cummins for years with stock boost as high as 32-35 PSI, and HP in excess of 400. My ISC-350 runs about 23 PSI boost. I installed an EGT gage on this coach as well as my previous Cummins-powered coach, which I also "hot-rodded" with no problems whatsoever. I know what my EGT's are, what causes them to rise or fall, and what I need to do to keep them within safe operating limits.
that's great, that's all I advised is to make sure your monitoring your EGT's if your gonna play with the fire. Never asked for a pompous remark



Knowledgeable people with HANDS-ON EXPERIENCE have been improving the performance of diesel engines without problems since before Cummins itself hot-rodded one of its own engines and entered it in the Indy 500 in 1931.

Capt'n obvious ehh

I'm not trying to scorch you, but I did ask for replies from folks with REAL-WORLD EXPERIENCE, not those who parrot what they have read. Misquotes from "Auto Shop 101" don't contribute anything of value to any post.
have worked on Cummins and Cat motors in charter boats (offshore fishing yachts) since I was in high school, you dont know who I am or what I have done. I don't need a prima Donna with pompous remarks telling me what I do and don't know

My real world experience is what I said. You're not doing a dam thing by adding more boost without the fuel, fuel is your power, you even stated for the past 20yrs diesels have been operating with excess air (boost)(shall I requote that for you?) what the h#ll does adding even more gonna do for you . Adding more boost without fuel is like cleaning your teeth from your @$$ instead of through your mouth.

Have a good day Sir!
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Old 03-03-2020, 05:34 PM   #12
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Just thinking out loud:

Since the ECU reads actual boost, is it possible that excessive boost beyond factory spec. will cause the ECU to go into derate mode, and actually produce less power?
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Old 03-03-2020, 07:18 PM   #13
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Im running 30psi max boost on my HX35 turbo on my ISB 5.9 but i also installed a cometic tri metal head gasket and ARP studs and Banks tuner with gauges. The Banks system automatically controls EGT max temp. Around 5k miles so far no issues lots more power available, great fuel economy, no regrets. Best of luck to you.
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Old 03-03-2020, 07:23 PM   #14
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Just thinking out loud:

Since the ECU reads actual boost, is it possible that excessive boost beyond factory spec. will cause the ECU to go into derate mode, and actually produce less power?
My Banks tuner reads the actual intake pressure then sends a lower pressure signal to the ECM to make it happy. The Banks also controls the fuel rate so its in full control.
They provide a harness that goes between the ECM and the sensor, plug and play.
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