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+--- Thread: Simple mods to increase power (/showthread.php?tid=2474)
Simple mods to increase power - playadude - 04-04-2011
Hi,
After reading these forums, I've decided that I want to:
- Set my boost to a higher PSI (14psi or so ?)
- Remove exhaust gas recirculation system
- Remove oxidation catalyst (OxCat)
- Replace stock muffler with a resonator (less restriction)
Thank you, Pete in Denver
- I have a 1991 3.5 liter diesel (rod bender)
- Recalled and rebuilt in 2001 ($10,000 cost)
- I have a rebuilt transmission.
- Car runs and drives perfectly
RE: Simple mods to increase power - led-panzer - 04-04-2011
You won't see all that much unless you turn the pump up. Those things all help though.
RE: Simple mods to increase power - playadude - 04-04-2011
(04-04-2011, 12:36 PM)led-panzer You won't see all that much unless you turn the pump up. Those things all help though.
So I'm describing these items correctly?
Also, Pump means Turbo right? Do you think 14psi would be a ton more strain on the motor?
Thank you,
RE: Simple mods to increase power - yankneck696 - 04-04-2011
Pump means the Injection Pump, which controls fuel.
Ed
RE: Simple mods to increase power - muuris - 04-04-2011
I'd say forget any planning for engine tuning until you know what the pump means in these (and how a diesel engine works, does the power come from air, is there a controlled constant air/fuel ratio as in petrol engines etc...)
Also, if your mechanic doesn't know how to up the power without your list, there is a great risk of something going wrong.
Better to have a stock, fully functional car than a "tuned" one that won't work properly, right?
RE: Simple mods to increase power - yankneck696 - 04-04-2011
Yeah, what Muuris said... Browse the forums for a week or so, then decide if you still want to persue the idea. At least you will be better informed, or understand enough to have the confidence to do it yourself (much more satisfying).
Ed
RE: Simple mods to increase power - playadude - 04-04-2011
(04-04-2011, 01:38 PM)muuris Better to have a stock, fully functional car than a "tuned" one that won't work properly, right?
Agreed, however,
I understand that MB had to add more emissions equipment to the engine, and that equipment required more power, so they increased the engine size to 3.5. However, the 3.5 still does not produce the same horsepower as the older 3.0.
I know that everybody hates the 3.5, but mine was rebuilt 10 years after it was first introduced. Surely, MB figured out how to fix the problem.
My point is, I want to get rid of junk on the engine that doesn't do me any good, and that was introduced in 1991 for environmental, noise, or other issues.
EGR, OxCat, and anything in the tailpipe, etc.
Perhaps I would leave the Pump and Turbo pressure alone.
Pete
PS. Thanks for helping me guys, sorry I'm so stupid about stuff you guys know a ton about. I sincerely appreciate any advise you can give me.
RE: Simple mods to increase power - 300D50 - 04-04-2011
You're not stupid, you just didn't know it. There's a big difference between the two.
RE: Simple mods to increase power - ForcedInduction - 04-04-2011
(04-04-2011, 12:27 PM)playadude [*]Set my boost to a higher PSI (14psi or so ?)Waste of time.
Quote:[*]Replace stock muffler with a resonator (less restriction)Waste of time.
Quote:I have to ask my mechanic to do this since I don't have the skills necessary.He will not legally be able to do it.
RE: Simple mods to increase power - ForcedInduction - 04-04-2011
(04-04-2011, 12:36 PM)led-panzer You won't see all that much unless you turn the pump up.
Thats the ONLY way to increase power.
RE: Simple mods to increase power - playadude - 04-04-2011
Forced!
What equipment on my engine is superfluous? I know that they used to put Air Pumps on engines for emissions.
Does my engine have stuff on it that I can get rid of? Stuff that is just making it work harder?
Pete
RE: Simple mods to increase power - ForcedInduction - 04-04-2011
(04-04-2011, 02:46 PM)playadude Does my engine have stuff on it that I can get rid of?Legally that your mechanic can do, no.
RE: Simple mods to increase power - aaa - 04-04-2011
Get a boost guage and see what your boost is before you mess with it.
(04-04-2011, 02:38 PM)ForcedInductionQuote:[*]Replace stock muffler with a resonator (less restriction)Waste of time.
The 126 and 124 exhausts are different from the 123, they're more restrictive.
RE: Simple mods to increase power - ForcedInduction - 04-04-2011
(04-04-2011, 02:48 PM)aaa The 126 and 124 exhausts are different from the 123, they're more restrictive.
Incorrect. That is why they installed two resonators instead of one.
RE: Simple mods to increase power - led-panzer - 04-04-2011
If were going to take the stance that everything the OEM did was the best that can be done then this site shouldn't exist.
Improving air flow into and out of the engine is important, even if it doesn't increase horsepower directly. Airflow becomes more important if he does turn the injection pump up
RE: Simple mods to increase power - Captain America - 04-04-2011
The weight savings will help. I'd guess mine weighed at least 50lbs
RE: Simple mods to increase power - larsalan - 04-04-2011
(04-04-2011, 04:51 PM)led-panzer If were going to take the stance that everything the OEM did was the best that can be done then this site shouldn't exist.
Improving air flow into and out of the engine is important, even if it doesn't increase horsepower directly. Airflow becomes more important if he does turn the injection pump up
And that's why Forced was running that 4in hood stack with his compound turbo setup
I don't get how he can play both sides. Extreme mods and no mods cause they are all illegal or bad for the environment etc.
RE: Simple mods to increase power - ronnie - 04-04-2011
You may want to check your local laws. mostly what inspections do you have? Removing any emisions equipment is of course not legal, however if there is no inspection that would catch it then there would be no inforcement.
So assuming you do not have to have it smog checked, I would bring all things up to factory specs first,
Check fuel pressure
boost pressure, would not turn up boost until turning up the injection pump. This is something you need to do with someone experianced in doing so. Your local mechanic may not know enough to do this properly,ask first.
valve adjust if this engine has adjustable valves( I have 616, and 617's, so not up on this engine)
egr usually can be blocked off in a way that all parts are still there, just disabled.
Then see if you like it.
RE: Simple mods to increase power - erling66 - 04-04-2011
My advise would be to buy a few books. One about basic diesel engines and one about tuning them. After you read them, you will start to understand what people are discussing in this forum. And after that you will be able to do some tuning yourself. It is a great feeling when you tune a car and feel some difference afterwards.
There is no fun in having a mechanic doing the tuning for you
RE: Simple mods to increase power - larsalan - 04-04-2011
(04-04-2011, 06:14 PM)erling66 There is no fun in having a mechanic doing the tuning for you
totally, and if you do get to a project where you need some fabricating help or something and explain what you need to a mechanic they'll be interested to help.
here is an bit about diesels I find interesting
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/diesel.html
also wikipedia is a good place to jump off
RE: Simple mods to increase power - babymog - 04-04-2011
Lets start at the top.
Remove the EGR: This will yield no measurable power increase, but it will stop the oil/carbon mix in the intake from continuing to gunk it up and restrict airflow. You could then remove the crossover tube and intake to clean all of the tar out of it, which shouldn't return after the EGR delete.
Increase boost: As others have mentioned, more boost will create no more power without more fuel, in fact it will create increased exhaust backpressure. No gain.
Remove Oxydation Catalyst: You don't have one on a '91. The inclined-injection head burned clean enough that it didn't need the earlier trap-ox or catalyst.
Replace muffler with resonator: Although it might reduce backpressure somewhat, the turbo wastegate opens around 2500rpm, adequate air is not a problem on these engines.
Turn up pump: This, combined with extra boost, can increase power. However, your engine already makes more power/RPM than the 3.0L engine. The difference in max. HP between the OM603.96x (3.0L) and the OM603.970 ('90/'91 SD/SDL) is due to the max. RPM of the 3.0 being 5150rpm, and the early 3.5L (yours) at 4550RPM. Horsepower is torque and RPM combined, reduce one or the other and HP drops.
To that goal, I wouldn't recommend turning up the 3.5L (much anyway). The OM603.971 ('92-up) did run a little higher RPM, IIRC around 150RPM more, but never was run at 5000+ RPM like the 3.0, and unless someone can find out exactly why, ... I'd keep that long-stroke engine down. The engine also gained a windage tray due to the close proximity of the crank throws to the 6mm higher oil level in the sump, the lower wrist-pins in the shorter pistons increased the rod angle and side-loading on the pistons, they were pushing the limits of the metal and available space in there.
Another point touched on above, there was nothing added to the 3.5L for emissions AFAIK. It actually burned cleaner than the earlier 3.0L due to the new prechamber design, so it didn't need the Cat. This involved angling the injectors 5* toward the rear of the car, changing the mixer/ball shape in the prechamber, and 5mm shorter glowplugs to stay out of the fuel stream and improve mixing/starting. Oh, it also got "afterglow" where the glowplugs will cycle on/off with the engine running depending on coolant temps, which was an emission and cold-idling improvement but has no negative effect on power.
So enjoy the car, keep it all together, it's fairly robust as-is.
RE: Simple mods to increase power - totaldisaster - 04-04-2011
Babymog,
Would you also suggest this is NOT the engine to go over-boosting and dumping generous amounts of fuel into considering the history?
---Other than being rebuilt, what specific information do you have about the rebuilt engine, playadude?----
RE: Simple mods to increase power - playadude - 04-04-2011
(04-04-2011, 06:53 PM)babymog Lets start at the top. ...
... So enjoy the car, keep it all together, it's fairly robust as-is.
Wow! I researched rod-benders for months before I bought this car, nobody online had the kind of information that you have.
I'm extremely happy to find you. I never get the car above 3,200 RPM, (even when shifting) usually never above 3,000. I am very careful with my cars, (I treat them like a baby) and my main concern with this one was crap like air pumps and the like.
I didn't want to keep any extemporaneous, unnecessary equipment.
Thank you babymog, it is a true pleasure to have met you.
Pete
PS (I want a Unimog too, but don't have anyplace to keep it, and my wife would kill me :-) )
(04-04-2011, 07:33 PM)totaldisaster ---Other than being rebuilt, what specific information do you have about the rebuilt engine, playadude?----
Here's my confession ... I bought the car, sight unseen from a Doctor in Texas, it was his mom's car who is also a Doctor. He told me that it was recalled and rebuilt by Mercedes and I trusted him.
He could be totally lying to me, but the car does have good power and doesn't burn any oil.
Oh, yeah, his Mom is elderly and couldn't get any records together, so I don't have her service history.
I know, perhaps I'm being lied to. (I'm waiting for all of you Pro's to start giving me a hard time about this.) I hope my trust was not mis-placed.
RE: Simple mods to increase power - babymog - 04-04-2011
If it's original, there is a paper VIN sticker like the one on the body panels, on top of the bell-housing flange on the block. If it is a factory re-man engine, there is a stamped metal tag riveted there. Also, you can check the VIN to find the original engine number, which is stamped on the engine block top where the head doesn't cover it, just rearward of the fuel filter stand.
The head is another item to check. The head has a sequence of numbers cast in just aft of the #2 injector, "603.XXX.YY.ZZ" The numbers YY in this example (16-22) tell the head casting number, should be 16 or higher. If it's higher, the head also has been replaced.
Watch for oil useage. There are a few theories out there as to why the engine bends rods, one that I have gotten to favor is the possibility of head-gasket leaks leading to hydrolocking as the engine can hydrolock with around a teaspoon of fluid. Be sure to not overheat, and if it's smoking or cross-contaminating oil or coolant, get it fixed.
A very nice car really. I had a '91 SDL with ASD and SLS, miss the car and those options.
RE: Simple mods to increase power - playadude - 04-04-2011
(04-04-2011, 08:40 PM)babymog If it's original, there is a paper VIN sticker like the one on the body panels, on top of the bell-housing flange on the block. If it is a factory re-man engine, there is a stamped metal tag riveted there. ....
Thanks babymog, what do you think about me running it at 2,500 to 3,200 RPM (thats 60 to 80 mph, about as fast as I need to go).
Does it hurt these motors to run them higher?
The funny thing about this motor is how smooth it is at 1,000 to 3,200, it revs really well, and sounds great at speed. Kind of like it "likes" to be 'reving." When it idles, it sounds like a big diesel. When it's at RPM, it doesn't.
RE: Simple mods to increase power - winmutt - 04-04-2011
Re exhaust, straight pipe it from the down pipe to the rear muffler, removing the cat and the resonator. It makes a noticeable difference.
Turbo 13psi is nice. Using a manual boost controller will keep the WG from bleeding prematurely.
Are you talking about the trap oxidizer or the catalytic converter? I am assuming you have no trapOx and are referring to the catalytic converter when you say Ox Cat.
RE: Simple mods to increase power - babymog - 04-05-2011
It will be very happy at 3200rpm, it's designed for it. Mine (the 3.0L version) revs happily to 5400rpm and makes lots of power all of the way up.