Intercooler boost pressure on 603.... - PeachParts Mercedes-Benz Forum

87tdwagen · #1 11-07-2005, 10:48 AM

Hello all,

Just installed my IC on my 603 and took it out for a quick spin just to make sure everything held together. It did so far, but I noticed a lower boost pressure on my gauge. The pressure builds up more slowly now and it tops out a couple of psi less than stock.

Now granted I just added 6 additional feet of plumbing underhood and I was expecting a slower boost spin-up, but is the lower presure limit due to the:
1. system capacity increase??
2. the cooling efficiency of the IC??
3. Leakage in the system??

I cannot hear any audible leaks while driving and none fealt at idle. I have not had much luck convincing my friends to help me take off the hood so they can lay prone on the engine bay while I make some full boost passes and then tell if there is a leak or not. Any takers on this list

Any help would be appreciated, expecially anyone who has done this conversion and noted the changes, experiences etc.

Thanks

boneheaddoctor · #2 11-07-2005, 10:51 AM

Quote:

Originally Posted by 87tdwagen

Hello all,

Just installed my IC on my 603 and took it out for a quick spin just to make sure everything held together. It did so far, but I noticed a lower boost pressure on my gauge. The pressure builds up more slowly now and it tops out a couple of psi less than stock.

Now granted I just added 6 additional feet of plumbing underhood and I was expecting a slower boost spin-up, but is the lower presure limit due to the:
1. system capacity increase??
2. the cooling efficiency of the IC??
3. Leakage in the system??

I cannot hear any audible leaks while driving and none fealt at idle. I have not had much luck convincing my friends to help me take off the hood so they can lay prone on the engine bay while I make some full boost passes and then tell if there is a leak or not. Any takers on this list

Any help would be appreciated, expecially anyone who has done this conversion and noted the changes, experiences etc.

Thanks

Have you tried plying them with beer?

87tdwagen · #3 11-07-2005, 10:55 AM

Quote:

Originally Posted by boneheaddoctor

Have you tried plying them with beer?

That and pizza, nothing works, yet somehow they all offer to do the driving part

Red Pike · #4 11-07-2005, 11:03 AM

The intercooler provides additional head loss in the air charge line. Depending on the configuration, significant additional losses can occur at each elbow in the line from the turbo to the intercooler, and from the intercooler to the intake manifold. If the lines to and from the intercooler are smaller than the stock connection to the intake manifold, this, too will add losses. Finally, the additional length, and any internal roughness of the lines, will contribute additional losses.

87tdwagen · #5 11-07-2005, 11:13 AM

I managed to keep everything intact as OE except the following items which were deleated:
1. EGR somehow the only part that got lost in the process, hmmmm
2. EGR Mixer pipe mid section and top crossover coupler
3. #1 cylinder heatshield the little short one in front of the header.

All else stayed or was reused.

Intake mods include the removal of the airbox and isolation as well as insulation of the airbox chamber.

Keep ya posted on EGT results and what not

87tdwagen · #6 11-07-2005, 11:19 AM

Quote:

Originally Posted by Red Pike

The intercooler provides additional head loss in the air charge line. Depending on the configuration, significant additional losses can occur at each elbow in the line from the turbo to the intercooler, and from the intercooler to the intake manifold. If the lines to and from the intercooler are smaller than the stock connection to the intake manifold, this, too will add losses. Finally, the additional length, and any internal roughness of the lines, will contribute additional losses.

Thanks Red,

Floating out another idea, of course I could up the boost vian the controller to the point where I regain at least stock boost pressure, maybe more if I up the fuel. I guess is I have say a 20% loss of pressure due to system inefficiencies, if I run 18psi at the turbo, my manifold pressure should drop by the 20% to ~14psi in my manifold.

Any idea of the upper safe limit for this turbo? Can they safely operate at say 20 psi without major risk of damage? am I gonna blow up this thing...

Mitch H · #7 11-07-2005, 05:28 PM

If your turbo has an external hose to the wastegate, get a longer hose and hook the wastegate up to a post-IC pressure source.
The overboost protection solenoid kicks in at 17psi or so. From what the Finns say, the stock turbo gets pretty inefficient if you go much higher than that, so you may as well stick to 15-17psi post IC.

87tdwagen · #8 11-07-2005, 06:41 PM

Quote:

Originally Posted by Mitch H

If your turbo has an external hose to the wastegate, get a longer hose and hook the wastegate up to a post-IC pressure source.
The overboost protection solenoid kicks in at 17psi or so. From what the Finns say, the stock turbo gets pretty inefficient if you go much higher than that, so you may as well stick to 15-17psi post IC.

This should really help. I was pushing it a bit harder this afternoon and I kept hearing a pssst at about 12psi on my gauge (manifold), the pressure would not drop below nor go above, maybe the overboost relief system is kicking in? No obvious sources of leakage noticed anywhere.

will keep on at it,
Bill

Hit Man X · #9 11-07-2005, 06:51 PM

I'd try to bypass the overboost solenoid first. If not, that IC has a pretty high pressure loss.

Where did you pick up the core?

Brian Carlton · #10 11-07-2005, 07:01 PM

You really ought to have a look at this thread over on BuyMBparts:

http://***************/forum/showthread.php?t=159&page=1&pp=20&highlight=intercooler

Casey (H202 over here) has a thoroughly detailed progress report on installation of the intercooler in an '87 300TD and his subsequent adjustments to the pump to get proper performance out of it.

There is nothing comparable to the work and the documentation that he has done.

Enjoy the read.

87tdwagen · #11 11-07-2005, 07:29 PM

Quote:

Originally Posted by Hit Man X

I'd try to bypass the overboost solenoid first. If not, that IC has a pretty high pressure loss.

Where did you pick up the core?

Hitman, the core I'm using is from a SAAB 9000T, its 9x9" not too big but it fits under the passenger overhang nicely. I'll also ckeck out boost solenoid as suggested.

Thanks,

87tdwagen · #12 11-07-2005, 07:30 PM

Quote:

Originally Posted by Brian Carlton

You really ought to have a look at this thread over on BuyMBparts:

http://***************/forum/showthread.php?t=159&page=1&pp=20&highlight=intercooler

Casey (H202 over here) has a thoroughly detailed progress report on installation of the intercooler in an '87 300TD and his subsequent adjustments to the pump to get proper performance out of it.

There is nothing comparable to the work and the documentation that he has done.

Enjoy the read.

Thanks again

Hit Man X · #13 11-07-2005, 10:53 PM

Quote:

Originally Posted by 87tdwagen

Hitman, the core I'm using is from a SAAB 9000T, its 9x9" not too big but it fits under the passenger overhang nicely. I'll also ckeck out boost solenoid as suggested.

Thanks,

Hrm, that could be why! I know many stock ICs have high pressure drops through the core. That WRX I had was a 2.5psi drop!

I think those Turbo Volvos are even worse.

t walgamuth · #14 11-07-2005, 11:03 PM

my cummins has a huge intercooler. i have no idea what boost it runs but it is getting 370 hp and 500 ft lb out of 5.9 liters. and the o5s are rated at 600 ft lbs so i am guessing they just turned up the boost and fuel. i guess that is not all that much more than the 603 in terms of power per displacement.

the cummins has four valve head and iron head too. and it doesnt make the temp go up even when towing my 35' travel trailer at 73 mph.

it is fun to watch your progress. hope it all works out for you.

tom w

#15 11-07-2005, 11:41 PM

Remember that with any good intercooler...you are trading off between space considerations, IC size (efficency), and pressure drop from inlet/outlet.

The Volvo IC's cool down the air real well but they have losses as far as pressures go and stacking in the IC.

A smaller IC (Audi, etc) works good to get less psi drop but now you are starting to loose your cooling efficency.

I am toying with the idea of taking this IC I have (aluminium) and going air/water and just doing without the silly piping.

Anyone interested in a setup using the stock air cleaner!