603 Power Increase Questions
 

I think I have this straight, am going to embark on a modest power increase project on my 300D/603.

Boost is limited first by the overboost protection: sensor on the intake plenum which cuts boost to the ALDA at 10.5psi.

If that fails, the wastegate will open at 15.6psi.

Both of these limit boost, to increase boost one would need to change the wastegate spring and eliminate the overboost protection circuit.

Fuel enrichment is limited by the ALDA which essentially meters the fuel to the intake plenum pressure, via the overboost protection circuit. Can be enriched, but only slightly, by adjusting or removing the ALDA.

Maximum fuel flow is adjustable in the fuel injection pump AKA: IP, but it can only be increased a little bit, limited by the plunger size/volume.

RPM is limited by a governor internal to the IP, Centrifugal I'll assume, and probably against spring counter-pressure (which might weaken over the years from wear and increased tolerances). If so, it is likely that (like many mechanical governors) its job of limiting no-load max. RPM costs some power in the top of the RPM band as the mechanical governor requires some throttling zone.

The power curve on the 603 is still in a good rise/slope when it hits redline, so it apparently has the abililty to breath pretty well at the top end.

Correct me if I'm wrong please.

So, I'm installing a 55-trim turbo from a 3.5L engine, a 17 head to handle the additional pressure, and a 3.5L IP. The 3.5L IP should be able to deliver more fuel than the 3.0 IP? Or is it the same IP with the same elements, just turned up a little? Different cam or the same?

To use the additional fuel and add some boost pressure, I guess I'll have to change the wastegate spring, or add an adjustable rod. What have people here used to increase boost? Also, is there a way to change the overboost protection sensor to a higher PSI?

I know I need an aftercooler to use this fuel and boost safely, still working on that, and I plan to retain my A/C functions so I can't stick it where the condensor is now.

What about ALDA? Will the stock one be fine with turning the IP up? Just reduces fuel at low boost right? So 10psi+ should have the ALDA limited out and revert to the IP settings?

Not going to go crazy, just would like to get north of 200hp if possible. bigger exhaust and such are not in the cards at this point. What about the stock auto-trans though? Is anyone out there running 200hp through one successfully? The differential? Engine mounts and subframe/suspension issues with the increased power?

I haven't seen anyone lately who has done this and talked about it, was a guy with a 126 a while ago, think he crashed it though and isn't on the forum anymore. I'd sure rather do this right the first time instead of breaking things as I go, learn from the experience of others, it's cheaper that way.

Oh also, is a wastegate necessary? My big CATs didn't have one, just wasn't enough fuel to overboost, what is the max the engine can take for short runs, and can the turbo generate that much without serious fuel mods?

Thanks for any advice,

You have those backwards. Your wastegate is opening at 10.5psi and the overboost is tripping at ~1.1bar (~15.9psi).

The 3.5L pump uses the same 5.5mm plungers, just different tuning.

HERE is what you need to set the boost pressure.

Absolutely. Your cats have a turbine A/R matched to the engine's power specs. Removing the wastegate from a wastegated turbo WILL overboost. Setting the boost pressure higher than you need is just wasting energy, you don't need 25psi of boost just to get 200hp.

Thanks for clarifying the boost limiting for me FI.

I think I'll build the MBC you've linked, but with a return line w/ check valve instead of the bleed hole, that will allow the wastegate to return to rest as the blowoff pressure drops. I think I have all of the SS pneumatic fittings in the shop, should look pretty ;~)

Are the 3.5L '91 nozzles the same opening pressure as the '87 3.0? Might be the 3.5 has a higher injection rate to help emissions, different cam profile and timing, but that would likely take a lower "pop" pressure.

Do you have the link to the DIY for turning up the IP output? I haven't been able to find it, was on this forum.

I'm not sure if it does. I do know the 3.5L uses different injector bodies with an angled precombustion chamber design.

I also know the OM606 turbo (98-99 E300) uses 6mm elements in it's pump. You can swap/buy those larger plungers into your existing pump.

There is a good guide HERE.

That's the one, thanks!

Can the 606 pump be used? If so, what should I look for?

I'm working on my 350D trunk badge, ... if I have a good mid-life 3.5L, why not drop that in and start with a bigger engine? If it made it 200k without bent rods, ... am I poking the bear to turn up a 3.5L?

If a 606 pump does swap in, I would think you'd only want one from a 1995 since I believe that is the only mechanical 606. Or maybe I'm getting i confused with something else ane there is in fact no mechanical 606...

Most of the time, I hear about modded 603 pumps being used on 606's for more performance, not the other way around.

I'm pretty sure the non-turbo 606 pumps are the same 5.5mm as the 603.

Go for it! I haven't seen anybody make one yet. Although, when people fail they usually don't archive their failure on the internet for everyone to see....so there probably has been attempts, just no record of their success/failure.

I agree. There's no sense squirting more fuel into an engine that doesn't have enough air in the first place. The turbo version of the engine is another thing.

Does anyone know the stock horsepower of the 3.5L 603?

Is this a North America only engine? Wondering if the Finns have ever played with the 3.5, or if there's a reason they don't. It'll probably be out of the car by the weekend so I can tear it apart and determine its fate.

I think the weakness of the rods in the 3.5L engine would keep it from being a good candidate to bomb... unless one had bigger rods made perhaps... I think you could safely squeeze more power out of a 3 liter engine because the cylinder walls are thicker though, as well as the liners.

Think the 603 3.5 liter engine puts....
 

[QUOTE=babymog;1826603]Does anyone know the stock horsepower of the 3.5L 603?

Out about 15 horse power less than the 3.o liter version, so instead of 150 it is about 135. Not sure about torque but think it is less also.

Regards

Run-Em

The 3.5 has more torque but less HP due to the lower redline. (fuel cut is 4100 rpm on the 3.5)

-J

I think the 3.5 has around 229 ft-lbs and the 3.0 has 187? Less than 200 though. Also, I think the 3.5 peak torque is at 2000 instead of the 3.0's 2400. Could be wrong on that

Okay, new plan.

Car: '87 300D

Engine: 603.960, .5qt/5000miles Mobil Delvac 1, seems solid. ~200,000miles currently, I've been driving it on/off for about a year.

Donor Engine: 603.971.

.960 Long-block retained.

Head: #22 from donor.

Turbo: Garrett 55-trim unit from donor. Adjustable wastegate rod installed.

I.P.: 603.960 unit for higher RPM and higher HP of .960 engine, full-load limit turned up. Also watching the delivery-valve shoulder trimming thread. Here's where I need more information though.

My diesel tuning has been mostly CAT and DD. In the CAT when I changed IP, I also had to change nozzles. The injection rate changed in the new pump, and the pop pressure /flow rate of the nozzles were matched to the pump, so new nozzles. From what I hear so far all M-B turbo nozzles are 135bar pop, so they should match? Also, the .960 engine put out more power, and at higher RPM, so it makes sense that the IP and nozzles had to inject more fuel during a shorter time than the slower/lowerHP .971.

Will the .971 nozzles restrict flow or are they the same flow? Seems that the .96x nozzles won't fit the .97x head (different pre-chambers) so I need to retain the .97x nozzles or do some machining, does anyone know of any differences between the .97x nozzles and .96x nozzles? Emissions was IMO the main reason for the .97x engine, which could have driven changes in the nozzles and I.P., that's what worries me.

Moving down the line, ... the .971 oil pan (sump) is apparently larger than the .960 pan, will the .971 pan fit in the 124? Will the .961 pan fit in the 124?

Next is the cam. I'm figuring the .97x cam has retarded exhaust timing for emissions and planning to use the .960 cam, but don't know. Anyone know how/whether the .96x and .97x camshafts differ?

Aftercooler is still an unknown, and probably the largest hurdle.

Thanks for any information on the .96x vs .97x injection pump and nozzles.

<edit> Also installing the "afterglow" glow-pllug relay from the .971.