C-8.3 mechanical engine turbo & fuel changes

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C-8.3 mechanical engine turbo & fuel changes

November 16, 2013, 06:27:17 pm

We have an opportunity to make a small increase to our well-running 1997 model-year Cummins C-8.3 mechanical engine power and wonder if we should proceed.

Our engine runs fine with no overheating, but it has never been looked at or adjusted during its 16 years of being on the road.

We understand our current OEM turbo, which now will reach 19 psi, is capable of producing about 24 psi. Plans are to increase a few psi, but not push to its 24 psi limit.

And with increased psi, fuel injector pump needs to increase the amount of fuel injected into cylinders to keep air-fuel ratio in balance.

Questions:
Are the above correct and do they make sense?
Anyone have experience with these 'peaking' adjustments?
What to watch for during adjustments and afterward?
Can we expect a little more power?
Since the engine has never been adjusted, does it seem logical to make sure it is in spec and to increase it a bit?

Thanks,
Barry & Cindy

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #1 – November 16, 2013, 07:57:59 pm

Barry and Cindy, hope you are both well.
To answer your question in a way. The coach we have (you know it) it is an 8.3 350 Cummins and the last owner put the Banks Stinger in and that can give us 32/34lbs of boost tops. We have no overheating issues or pump problems and there is about35k miles since that addition. I drive it hard like I did with all my cars. I could not go back to a "before" condition as it seems like it is dragging a load( had it not working for 2 days and hated it).
I feel the Resonator has added a touch, so not being a "gear head" I cannot give you #s etc but ours moves along nice.
John H

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #2 – November 16, 2013, 08:48:22 pm

On my ISM450, when installed the resonator, the turbo boost went up 3.5-4 psi, then when changed to the ISM500 setting it went up another 3.5-4. Have seen 34 psi, but normal would be 30-31 area, depending on rpm & gear.
I would also highly recommend having the valves adjusted at Cummins, did mine at 102,000 area, glad I did as they were little closer then wanted the clearance.
Too bad you can not run the VMSpc on the mechanical engine, it can provide lots of info.
No idea how the 8.3 responds to such.
Cheers

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #3 – November 17, 2013, 08:00:08 am

I got about 3 lbs of extra boost with the resonator on my M11 but have not upped it to 500 hp yet.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #4 – November 17, 2013, 08:10:26 am

I will watch this thread and hope you get good info. I too have not adjusted valves for twelve years. Years ago I did add a "wet" air filter for better flow and wrapped the turbo and exhaust to keep heat where needed. Creating a "hotter" engine is a concern of mine and so I tend not to explore or mess with what has been working so well.... andy1

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #5 – November 17, 2013, 09:17:26 am

I'm interested in seeing where this goes also, as I feel the 8.3 mechanical is close to an optimal engine but a little down on power as the toad/toys list grows. Lots of people put in the Banks kit and are happy with it. Before I do that, though, I'd probably exhaust other options, basically making sure the engine is in as fine state of tune and error free as possible. I have always liked the advice given by this mechanic, below.

The base 8.3 is a workhorse engine. If i had a coach this is probably the engine i would have in it. The p7100 pump is as bullet proof as the engine if you keep water out of it. [ good fuel system maintenance ]
When it comes to timing I think you should leave it where the factory said to set it. Remember when they designed this engine they designed it to work hard and have a very long and trouble free service life. Unless you truly understand what your doing to cylinder pressure and fueling leave timing set where it is supposed to be. Now we are assuming the timing is set correctly to begin with ok.
Does your engine have an after cooler or is it charge air cooled? If you dont understand what im asking look for large diameter pipes that go from the turbocharger outlet to the front of the radiator or side if you have a side and not rear cooling system. If it is charge air cooled and its an older coach have someone check the charge air system for leaks. It should have no leaks. Leaks in that system cause low power and smoke and poor fuel mileage and hot pyro temps.
Next make sure the primary transfer pump which is a piston type pump and is bolted on the left lower side of the block [ standing at flywheel looking over top and twords the front of the engine your left hand is left side of block ] is putting 35 to 45 psi of fuel pressure into the p7100 when the engines rpm is around 1200rpm. If its not there is a check valve on the front head side of the p7100. This check valve which looks like a big nut has pump fuel drain line hooked to it going back to the fuel tank. The nut is actually a check valve that looks like a big short bolt when you screw it out of the pump. If the check valve spring is weak or it has an issue fuel transfer pump pressure will be too low. If your not sure if the problem [ if you have one ] with transfer pump fuel pressure is the transfer pump or the check valve pinch the fuel line coming off that nut shut for about 10 seconds with a pair of pliars. Dont bother doing this unless you have a fuel pressure gauge hooked between the transfer pump and the p7100.
and yes you have to usually drill into the cap nut that holds the fuel line in to the p7100 and tap it to 1/8 pipe to put in a gauge. The gage should go to 100 psi as a good lift pump can put out 80 to 95 psi when dead headed. If yoiu close off the return line and the pressure is still only 20 to 40 psi the lift pump has issues. By the way dont close off the return line to save money if the check valve on the pump is bad [200bucks for valve ] if you close off that line you will seize the p7100 and a rebuilt exchange is ball park 3500 bucks.
so now you have fuel pressure and you made sure your throttle linkage is pulling the throttle lever to absolute full throttle. If it is not you are not moving the internal rack to fuel fuel and losing horsepower. Short 1/4 inch of full throttle can be around 40 horsepower loss. Also make sure the pull off solenoid is pulling the off lever all the way to its stop. It is designed to do this geometrically so as long as the pull off linkage inside the boot is not worn out or broken your stop adjustment should be correct. Next make sure the turbo wastegate can on the turbo is not leaking air from a bad diaphram. If it is even a slow leak due to the signal air plumbing you may not be opening the afc in the 7100 all the way. Once in awhile you will find the afc air in fitting on the 7100 loose in the can it fits in and that causes power loss too.
You didn't mention the horse power this was but i have seen them at 350 in trucks and run for 800k miles.
The headgaskets are very good with really no problems. If you jack the timing up you may cause premature headgasket failure. Make sure the radiator is in good shape and charge air cooler if it is not aftercooled. Most of the failures i see on this engine in a coach are due to the following. cooling system failure [ plugged or salt rotted radiator causing overheating and premature headgasket failure and more if overheated enough.
Next I see cracked exhaust manifolds and or cracked warped manifolds and or turbine housings as well. This is due to leaks in the charge air system or the boost system what ever you want to call it. If the turbo boost is below specs do to a system failure like a cracked charge air cooler or hole in a charge air boot the exhaust system will take some serious heat because the fuel cant burn in the cylinder due to low oxygen to fuel ratio so the burn continues slower and the fuel is still burning coming out the exhaust port instead of being consumed in the cylinder. I have seen exhaust manifolds so hot they almost look transparent. This drastically shortens engine life. Not to mention fuel mileage is in the dumper.
So if it was mine:
*check air[boost] system
*I would pull out the nozzles and take them to a good bosch shop and have them flow tested and spray pattern checked. Many times a new tip on the nozzle and the nozzle pop off adjusted back to specs will do magic for mileage and smooth running and power. If you want to tweak the 7100 pull it and take it to a trusted bosch shop with the nozzles and ask them to set it up a few percent. You will know if you find a good pump man because he can tell you what percent to set up the pump to enhance pulling but not waste fuel or over fuel. I wont tell you what percent so dont ask.
*cooling system inspected and radiator repaired or recored if needed.
*oil sample analyzed. This only costs around 30 bucks and is well worth the money. IF you do an oil sample change your oil and filter and then run the unit until it is time to change the oil again and then take the sample at the oil change. Know the total mileage on the oil sample. know the brand and viscosity of the oil. know any additives you might think you need to put in the oil but really dont need to put in. know if you added any oil between the change and the sample. Tell the sample lab the above and you will get a good sample. The lab will explain the sample to you if you dont understand what your seeing on the report and dont feel bad unless your a chemist you wont. But the sample is a very good litmus of what is happening inside your engine. Last I would take it to someone who was recommended as a good mechanic and pay them to look it over and see if they see anything that needs addressed with just a visual inspection if you dont want to pay them for the diagnostics i talked about. No dowl pin issues no headgasket issues a really darn good engine.
You said you wanted a reliable engine your mom could drive trouble free. My response here is to that end. There are many who can tell you how to boost performance to almost magical ends out of this engine. But remember "the candle that burns twice as bright only burns half as long" [ bladerunner ]
ok i wrote too much already and this was just all my opinion but it is worth thinking about what i said ;-)

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #6 – November 17, 2013, 03:55:22 pm

We appreciate the great responses to our questions on moving forward to increase our C8.3 power a little. What great clear reading and with many detailed things to check. Thanks guys for taking time to help us. We are going ahead to have our experienced engine mechanic do his magic this week. We will let you know how things turn out.

Others thoughts are welcomed, too.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #7 – November 17, 2013, 04:32:51 pm

Quote from: Barry & Cindy – November 17, 2013, 03:55:22 pm

We appreciate the great responses to our questions on moving forward to increase our C8.3 power a little. What great clear reading and with many detailed things to check. Thanks guys for taking time to help us. We are going ahead to have our experienced engine mechanic do his magic this week. We will let you know how things turn out.

Others thoughts are welcomed, too.

Without saying your mechanic should not be in charge the mechanical cummins injection pump used to be adjustable by itself.

Small plug on top of an part on the end of the fuel pump.

Early ones if memory serves me had a hex on top for a tool to remove it. Later may be safety wired.

Once removed a wheel with serrations at it edge was visible.

We marked the edge of the wheel with fingernail polish so you could count its turns.

Using a small screwdriver the wheel could be turned increasing the fuel pressure.

Same pump if memory serves me on 8.2 detroits and 5.9 cummins.

Noticeable increase on power. Free. Did quite a few over the years.

Many have hundreds of thousands of miles on them since. All brands.

Good safe starter mod. Most never went farther. Some went in to banks.

There are probably more technicaliy correct mods since but this worked well.

Two turns or so was available on most engines.

Mileage went up. No smoke. No heating issues. Just a little more.

Bob

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #8 – November 17, 2013, 08:21:26 pm

I have seen 25lbs of boost pressure on my Cummins 5.9 with the Banks Stinger package. Rarely but it has happened. Normal boost on hills with the cruise control engaged is about 20-23lbs. I do not think Banks messes with fuel feed with the Stinger package. There is one higher package with more HP and more Torque and perhaps that does.

The Banks Stinger package is a remarkable system. I had no idea that the coach we bought had it until I started looking closer at the instrumentation. The original owner had it installed and the paperwork is still in the coach. Banks claims that it increases HP to just under 300 and with 22,500 lbs coach weight that makes a nice weight-to-horsepower ration; the normal 5.9 is 240 HP and even that is better than 1 HP for every 100lbs.

Calculating weight to HP for many larger coaches it's not at all uncommon to see 400HP engines on 47,000 lb motor homes. Foretravel has always had a very good ration of weight to engine power in their coaches but the Banks system is just an extra without breaking the bank.

Craig

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #9 – November 18, 2013, 12:14:05 am

What exactly is a Banks stinger system? What does it cost. Does it need additional gauges to monitor boost, etc?

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #10 – November 18, 2013, 12:27:35 am

Quote from: Gayland Baasch – November 18, 2013, 12:14:05 am

What exactly is a Banks stinger system? What does it cost. Does it need additional gauges to monitor boost, etc?

http://www.xtremediesel.com/bankspowercumminsmotorhomestingersystem.aspx. There are other things you can do to improve performance which are less intrusive and more cost effective.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #11 – November 18, 2013, 12:47:44 pm

PatC, what can be done other than the Banks to improve performance as much, and not be, as you put it "less intrusive and cost effective"?
It would be interesting to hear as I have the Stinger package and see no effects of it on the Cummins other than better performance and better fuel economy??? But I am listening intently.
John H

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #12 – November 18, 2013, 02:58:27 pm

Looks like the turbo housing is changed along with a waste gate added. When I did a lot of turbo work in the 70's and 80's, we had to add fuel or there was only a marginal increase in power and the EGT (exhaust gas temperature) went down quite a bit. We did a lot of standing start quarter mile runs comparing stock, turbo install and then turbo with pump work. I remember a 240D Mercedes took about 34 seconds stock, 28 seconds with the turbo added and 18 seconds with turbo and fuel added. Probably only a hour or two on the bench to get the mechanical pump to increase the fuel. On the older 5.9 Cummins, you could pull the plate off the top of the pump and just take a file and remove a bit of aluminum so the lever could travel further. With the computer engines, it's just a firmware adjustment. A good shop will know how much fuel can be added without causing the EGT to go too high or black smoke out the back.

Pierce

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #13 – November 18, 2013, 05:24:07 pm

No smoke at all from my 5.9B with Banks. I was not around when the package was installed so I don't know for sure if they changed the fuel pump settings. But if they did, then they did a damn good job of it. I get decent EGT readings and good boost PSI from the system and I am pretty sure it's at least 15 years old.

I know that a good mechanic can get more out of an engine than "stock" (or even a new "chip") but Banks has got the system down well. And if their system blows an engine (which seems highly unlikely) at least you have someone to blame it on.

I drive conservatively (58 to 62 mph) but the extra safety margin getting onto a freeway is a major plus. Long, steep hills and I still have to shift down and go slower to keep the transmission temps reasonable. I do like getting better fuel economy and, as I have said many times, if my Foretravel got 20mpg I'd wouldn't want to drive anything else.

Craig

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #14 – November 18, 2013, 05:35:57 pm

I own a 97 5.9 12 valve and my 8.3 12 valve have the same P 7100 injection pump...You can go on line and look up tons of info on simple steps to get more power out of the pump for your FT but I have played around on my FT with exhaust, pump tuning, and yes you can make Big power out of the 8.3 but the trans hates it.. I had to back off mine do to harsh shifting and found the sweet spot around 50 to 75 extra HP, Any more a the trans will let you know fast its not liking it...Also if you pull the 4 bolts off the top of the pump to slide the cam plate you need to loose the factory muffler and install a pyro Gage to monitor your EGTs...High EGTs will kill a diesel FAST and so if your tuning the P 7100 pump to fuel harder, More air flow is going to be a must so the muffler has to go because it's big time restrictive....Just my 2 cents

FYI, Check your boost too, Some of the Charge Coolers on the 8.3 are known for welds cracking/Leaking Boost and this will deff make for a Sluggish Cummins..

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #15 – November 18, 2013, 05:58:07 pm

My Banks (and surely all) has a Pyro gauge and I watch it all the time while climbing hills esp".
I did have 3 holes in the CAC but not thru' the design, but by rubbing of the cooling rad (fuel return) mounted on the face of it. I repaired it myself and pressure tested the CAC to 45lbs for a few hours so I know it is good.
My Muffler has gone and I installed a resonator, so that is ok.
The Allison does NOT seem to have a problem and I also got rid of the Transynd and now have Amsoil "HighTorque Synthetic" in it, and I am convinced it IS working better AND cooler than before. My high Boost has been 34lbs but I keep it around 30 tops .
No complaints at this end at all, and I love the difference.
John H

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #16 – November 18, 2013, 06:01:44 pm

Transmissions without lockup are going to be much more affected by increased HP and will see higher temps.

P

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #17 – November 18, 2013, 07:48:39 pm

Hate to keep harping on the resonator idea, but if you do not have it, and you install it, you will kick yourself repeatedly for waiting. Of course some would not see a 200 hp increase, and some can detect a 50 hp increase, so if your one of the former, forget it.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #18 – November 18, 2013, 09:29:31 pm

Quote from: Dave M – November 18, 2013, 07:48:39 pm

Hate to keep harping on the resonator idea, but if you do not have it, and you install it, you will kick yourself repeatedly for waiting. Of course some would not see a 200 hp increase, and some can detect a 50 hp increase, so if your one of the former, forget it.

What unit did you install?

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #19 – November 18, 2013, 11:24:52 pm

I did mods of a #10 fuel plate, and muffler (resonator), and star wheel adjustment on my 1994 Bluebird BMC 37'. Spartan chassis, Cummins 8.3 turbo mechanical engine, MD3060 Allison trans. I have an extensive thread (11 pages) that includes discoveries, discussions, and dyno charts of the results. Thread here:
Brazel's Performance RV (BMC Service) - Wanderlodge Owners Group

Later I added pyro and boost gauges discussion here: Recommendations for boost/pyro gauges? - Wanderlodge Owners Group

I also bumped up the timing 2.5 degrees later.

I'll post this, and in the next post see if I can add attachments of the dyno chart results.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #20 – November 18, 2013, 11:28:54 pm

Dyno charts attached if successful.

This was on a brake dyno. Coach in direct drive (4th gear), Run up against rev limiter (2500 pm), hold pedal to floor as dyno consistently and evenly builds pressure using water as the resistant force against tires, Computer uses load cell to calculate torque and then horsepower as it "pulls" the engine down to the point where it has to downshift out of 1:1 ratio, full throttle during the entire test, let off when the vehicle kicks down out of 1:1 and at that stop the test.

Note: I watched an attached boost gauge2/11/10. At 2400/2500 rpm there is minimal boost, test starts, dyno load is induced, boost slowly climbs to max boost. No max boost on higher rpm range on test results below. Climbing a hill under load at high rpm in the real world equals more hp and torque than indicated on paper.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #21 – November 19, 2013, 12:48:05 am

Whether you do Banks or piecemeal there are great gains to be made off of a C8.3 without affecting reliability. The fuel plate available is the same one that Banks includes - designed by a retired Cummins Engineer. The Banks Holset body as far as I know is a stock one but includes a better waste gate control with (I think) a stronger spring. An MT643 trans is a little light for this power. An MT647 does just fine. 3060 6 speed, no problem. Biggest thing is watching the EGT. I seem to remember hitting 28 lbs of boost in mine. Dyno is what you really should do to dial it in whether you piece it together or buy a kit. Dyno it first to make sure its getting full throttle, no coolers leaks, etc. Then Dyno it after to see the results and be amazed.
Note - November/December Banks used to mark down their returned kits by 30-40%. Not sure if they still do, but its worth a call if you. I have recommendations written up in the archives on mine from 7 years ago. I did it all backwards and still loved the result.
If you aren't concerned about cost throw in a new charge air cooler. It is 30% larger than any stock one on a 280 with cast end caps vice welded plate.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #22 – November 19, 2013, 12:58:04 am

Dave, isn't it funny that we have (Craig and some others too) the Banks system and talk about what a difference there is in all around performance compared to the original, and yet some folks that do not have it say "not worth it or similar comments". They can jump in my coach any time they want and see for themselves what we talk about.
John H

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #23 – November 19, 2013, 10:59:13 am

Quote from: Dave M – November 18, 2013, 07:48:39 pm

Hate to keep harping on the resonator idea, but if you do not have it, and you install it, you will kick yourself repeatedly for waiting. Of course some would not see a 200 hp increase, and some can detect a 50 hp increase, so if your one of the former, forget it.

In my opinion, free flowing exhaust (getting rid of muffler and adding the resonator) along with larger fuel lines will do wonders for most diesels. Over the years I seen lots of diesels built up and they are more trouble prone and require shorter maintenance intervals. A mild boost if fine, but I seen lots of diesels built up to where they come apart if you are not careful. But I will admit that Gale Banks has the best commercial engine performance systems on the market.

Re: C-8.3 mechanical engine turbo & fuel changes

Reply #24 – November 19, 2013, 11:44:21 am

The ISC banks is truly a plug and play - because the electronic controls do all the protection and automatically cut back power and torque.

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