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  #1  
Old 10-05-2006, 03:03 AM
Student Driver
 
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Location: Hamilton, IL
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how much more boost (w126)

Ive been playing around with a new intake setup, mounting a a greddy BOV, and now i want to do something that will actully make more power on my w126. now from my understanding the stock boost is 3psi? now my DSM ran 10 stock and now boosts 16psi. (24 psi surges) on stock internals. and is daily driven. now i want to make the w126 at least livible. This is literally the slowest car ive ever driven/owned/riddin in/bla bla. now before i even think about hooking my mbc up to the wastegate. I want to know what these things can reliably boost at. I hear these cars will go 500k driven hard. now what about boosted hard? is tripling the boost (9psi) unsafe? imo thats still weak. but i know that would make a big difference.

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  #2  
Old 10-05-2006, 03:12 AM
bgkast's Avatar
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First off you can chuck that BOV...Totally useless on a diesel.

Your car should not be that slow. I would give it a tune up (valves, fuel filters ect), clean out the banjo bolt and ALDA line, and check the overboost valve to make sure it is not plugged. Then you can try tuning up the ALDA for a bit more off the line power. Try a search on each of these topics for step by step instruction. Also the stock boost is higher than 3 psi...but turning it up wont help with power with out more fuel which requires some more advanced work with the IP. If you turn up the boost and fuel you will need to monitor your EGT and possibly cool things down with an intercooler.
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  #3  
Old 10-05-2006, 10:07 AM
pawoSD's Avatar
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Stock boost is 13.5 psi from the factory, and the overboost protection valve kicks in at 15psi
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  #4  
Old 10-05-2006, 10:21 AM
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chances are youre going to need more fuel, not just more boost...
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  #5  
Old 10-05-2006, 10:38 AM
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Thumbs up

First, drop the Ricer mindset. This is a non-intercooled turbo diesel. Boost is around 13psi at stated. It's not faster at 16psi. You must add more fuel to yield more power, unlike a gasser where overfueling will drop EGTs.

Get the thing setup properly. Adjust valve. Set IP timing. Check cam timing. THEN start to play around.
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  #6  
Old 10-05-2006, 02:23 PM
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0-60 should be in the 12 second range, get it doing that before you tune it.

With a 617 or any one of these engines for that matter you need to add an intercooler to get any significant amount of additional power. If you have an EGT, you can increase boost and fuel a small amount, before the temps get high.
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  #7  
Old 10-05-2006, 05:44 PM
ForcedInduction
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Quote:
Originally Posted by midenginev8 View Post
Ive been playing around with a new intake setup, mounting a a greddy BOV, ... now from my understanding the stock boost is 3psi?
For the love of ***, STEP AWAY FROM THE RICER!
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  #8  
Old 10-05-2006, 07:57 PM
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Oh boy, here we go again. Not to be rude but you have two options:

1. Remove all that ricer crap, sell the MB and buy (insert jap crap here) to install the extra parts on the new ride.

2. Remove all that ricer crap. Learn to use the search function. What you seek has been asked, over and over and over and over and over, etc. Treat a MB well and it will treat you well. Learn how diesels work, they have only a superficial resemblance to gassers.

RT
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  #9  
Old 10-05-2006, 08:02 PM
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There is no 16g silver bullet for these cars.

Sixto
93 300SD
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  #10  
Old 10-05-2006, 08:36 PM
Student Driver
 
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for the guys who left positive replys thank you.
Ive started mounting my old dsm side mount intercooler in the fenderwell. i just have to plumb it. and rotate the snout on the turbo so it faces the passenger side.

ive been going through replacing maintaince parts. next i need to address the fuel shut off switch. as i have to cut fuel from under the hood to shut the car off.


as for those who accused me of being a ricer.

the only thing ive done that you can make that claim towards. is one thing. and that is Venting into the atomishere. so i like the sound of boost.. who doesnt!

there are no flashy colors, erector set wings, or fat cans. just things that either, add performance, or add TASTEFUL cosmetic appeal,

Your not talking to a 16 year old with fast and furious dreams.

need proof that im not a clueless newbie? need proof that i can and have built respectable cars?

try telling me my Carbed 350 SBC V8 4spd. powered Fiero rebody. is riced out will ya.

heres a link to the build threads for my car.
http://www.fiero.nl/forum/Forum1/HTML/060288.html
http://www.fiero.nl/forum/Forum1/HTML/058999.html
http://www.fiero.nl/forum/Forum1/HTML/060577.html

btw i turn my own wrenchs, and do my own bodywork.

and i have plenty of respect for orignal cars too.
my 73 karmann ghia vert is stock along with my 944
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Last edited by midenginev8; 10-05-2006 at 08:38 PM. Reason: more info
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  #11  
Old 10-05-2006, 08:45 PM
ForcedInduction
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Originally Posted by midenginev8 View Post
and that is Venting into the atomishere. so i like the sound of boost.. who doesnt!
Me. For those that know you are driving a Diesel and how Diesels work, they will be rolling on the ground in laughter when they hear it.

Example: http://www.youtube.com/watch?v=jT809VeHCEU

There is absolutely no need for a BOV on a diesel engine. They just look/sound (insert bad description here) on them.
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  #12  
Old 10-05-2006, 09:06 PM
Student Driver
 
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Quote:
Originally Posted by ForcedInduction View Post
Me. For those that know you are driving a Diesel and how Diesels work, they will be rolling on the ground in laughter when they hear it.

Example: http://www.youtube.com/watch?v=jT809VeHCEU

There is absolutely no need for a BOV on a diesel engine. They just look/sound (insert bad description here) on them.
I think that one would actully cause problems. its venting with out being under load. the spring is too soft. and i beleave it would leak boost under accelleration.
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87' Fiero cp.
Lamborghini Diablo replica V8 4spd.
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  #13  
Old 10-05-2006, 09:25 PM
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smoke gets in your eyes
 
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Quote:
Originally Posted by midenginev8 View Post
the only thing ive done that you can make that claim towards. is one thing. and that is Venting into the atomishere. so i like the sound of boost.. who doesnt!
The issue isn't what you want or don't want. Asking about a BOV for an MB Diesel suggests that you don't yet understand the engine. The ricer comments, IMO, are a good natured ribbing way of suggesting that you should have a better understanding of what you're dealing with before trying to oudo MB's engineers.

As you know from DSMs, a BOV relieves pressure between the compressor outlet and throttle body when the throttle closes suddenly (letting off to shift). In factory config 'wasted' boost is routed back to the cmporessor inlet. In modified config boost is vented to atmosphere for that 'pchew' sound. Your 300SD doesn't have a throttle body or throttle plate so there's not much of a boost spike when you let off the pedal. The BOV would only open if the wastegate stuck closed and the overboost protection system failed. Very unlikely events.

In general these engine need more fuel before they need more air. An IC usually comes later in the mod sequence from a noticeable improvement standpoint.

Sixto
93 300SD
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  #14  
Old 10-05-2006, 09:28 PM
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Just for kicks AND as long as you have the pressure gauge attached to watch your boost get a plastic hose clamp (like they sell at Advance auto) and pinch off the wastegate hose. Run the car wide open on the biggest hill you can find and see what kind of number you are getting. If it is under 10 then you have an issue with your wastegate leaking or something like that. It should go up to around 15 psi then fall off when the overboost solenoid takes the fuel out. To increase acceleration from a dead stop you need to tweek the ALDA. Do a search on it and you can read all about it. Also, somewhere in here is a write up to tell you how to turn the fuel up via adjusting the injection pump.
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  #15  
Old 10-05-2006, 10:20 PM
Student Driver
 
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Quote:
Originally Posted by engatwork View Post
Just for kicks AND as long as you have the pressure gauge attached to watch your boost get a plastic hose clamp (like they sell at Advance auto) and pinch off the wastegate hose. Run the car wide open on the biggest hill you can find and see what kind of number you are getting. If it is under 10 then you have an issue with your wastegate leaking or something like that. It should go up to around 15 psi then fall off when the overboost solenoid takes the fuel out. To increase acceleration from a dead stop you need to tweek the ALDA. Do a search on it and you can read all about it. Also, somewhere in here is a write up to tell you how to turn the fuel up via adjusting the injection pump.
my haynes manual will be in tommrow. if it dont cover the fuel ajustment ill do a search.

I addessed a waste gate related leak today. and replaced the hose. ill do some more mantainace. but turbo itself might be a issue. There is quite a bit of shaft end play. and front to back movement. and ive noticed that under hard acceration from 3rd gear the motor cuts out, like the turbo is failing to spool, surging. or there is not enough fuel.

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