Turbocharged project, done

[Guest trofeo73]

I have finally attemped it and am having some problems with it running right. At first the car had awsome power and ran well, (aside from the oil leak from one of the lines) My O2 sensor was connected as follows: One end was just wraped around another wire with nothing more than electrical tape, the other was butt spliced on the connecter that is part of the harness. Why am I mentioning this,,,well, at first, when it ran well I was getting a constant reading from the o2. At the second run, the o2 read:/ 0.00 for a long time , even while running. It would occasionally register though. While reading .00 it ran very bad. BTW I am blowing into the MAF, is that bad?? While getting a constant o2 reading it ran real well, very powerfull.

Here is the link to see what it sort of looks like

http://discussions.gmforums.com/attachment.php?postid=275666&s=6331af4ed3a75eab5fdbd4a5cb81a671

[Guest EDBSO]

Congratulations!

Try soldering O2 connector wires first.

Link requires user name and password <img src="http://www.aaca.org/ubbthreads/images/graemlins/shocked.gif" alt="" />

[Guest trofeo73]

Sorry, I will try and upload one tonight or tommarow. Does soldering it really make a difference? Or should a good electrical connection do?

[Guest trofeo73]

try this

[Guest EDBSO]

Solder will help with both the electrical and mechanical properties of the connection.

Are you running both exhaust manifolds through the turbo?

The O2 sensor is a long way from the heads and may not be running hot enough can it be moved closer?

[Guest trofeo73]

I have the o2 sensor right after the turbo as it is on most cars. I figured that it would be ok, right???? What happens if it does not get hot enough??? Would it register 0.00??? Anyway,I fixed numourous oil leaks(return line) and figure that if I can at least get that right I can drive it. I am running both sides through as well. When It all ran well it had a noticable increase in power! What do you all think???

[Guest Stan Leslie]

A reading of 0.00 is indicating "lean" and will force the engine to put in more and more fuel (which will cause the engine to run rough due to rich misfire). The 0.00 reading could be a wiring problem (I suggest soldering also) or it could be that the sensor itself is damaged internally.

[padgett]

a) Suspect you have bad wiring or a bad O2 sensor, if not getting hot enough it will read a constant .5ish, not zero.

which side of the turbo the MAF is on does not really mater. Which side of the throttle plate is something of a holy war. Personally believe in putting the throttle plate in front of the turbo for several reasons:

- faster response

- less back pressure

- less residual heat

Rationale: if the throttle plate is behind the turbo, it is like blocking the blower end of a vaccuum, the turbo inlet has ambient air pressure & the outlet is blocked. This raises the air pressure and temperature in front of the plate but slows the turbo and increases the exhaust gas resistance. This makes the turbo slower to spool up on demand and takes more power at cruise.

Putting the throttle plate in front of the turbo is like putting your hand over the suction side of a vaccuum. Blades are spinning in a partial vaccuum so run at full speed while absorbing less HP and generating less residual heat. When the throttle is opened, you are already spooled up. The only downside is that the turbo spins faster at cruise (most of the time) which may shorten life but can be controlled with a good waste gate system.

In my opinion putting the throttle plate in front of the turbo inlet is a win-win situation but does require some additional engineering. No difference in peak horsepower but consideable in engine temperatures, cruise MPG, and response.

Nice thing about a MAF system is that it does not care what the pressures are as long as you do not exceed the maximum by too much (in the stock Reatta "C" engine this is 170 gm/sec).

[Guest Buick Mike]

What are some cars that have the turbo behind the throttle plate? I'd like to see how that would work.

Mike

[padgett]

Covairs for a start. Almost any supercharged installation. With carburetors the long runners were liable to cause lags as the pump shot had to travel through the runners to the engine but with port FI this is not a problem.

With draw through you also get a smoother transition from non-boost to boost whereas with blow through you get one shot as the pressure behind the plate comes through then a drop as the impeller spools up.

This jump/drop/spool sequence is what is perceived as "turbo-lag".

Only downside is that you must relocate the throttle plate which requires blocking the water passage but that is hardest part.

[2seater]

I had sort of the same problem when I tried mine with the O2 sensor in the approx. original position. As soon as the engine temp. came up so it went closed loop it ran terribly. mine was even further away than yours. I looked at the stock GN location and it is just before the turbo inlet so it will stay hotter. The turbo uses a lot of the exhaust heat to make it work so it will definitely run cooler. One other reason to move it would be to avoid any additional possible exhaust leaks ahead of the sensor which will give a false reading too.I relocated mine to before the turbo on the front pipe, plus I am installing a heated three wire sensor. First solder the connection and see if that works. I am so envious. Mine is still in storage and it's 4deg. below zero F. right now. I figure it will be two months before I can try mine. By the way, it looks like the compressor outlet isn't connected to anything? <img src="http://www.aaca.org/ubbthreads/images/graemlins/grin.gif" alt="" />

[Guest trofeo73]

Yea, the pic is outdated, its all hooked up now. Looks alittle crude though. On my 88 sunbird 2.0 turbo, the o2 was after the turbo, the same for the merkur(the source of the turbo that is on my car) I wonder why they did that?

Anyway, I reconnected the 02 sensor and it ran great. I gave it hell and it broke the tires at 20 mph! The jet engine sound freaked out the teenage kids working on their cars! They ran to the edge of the street to see what was the cause of such a strange sound comming from an oldsmobile!!!!

I have been fortuneate to have nice weather here in southern mo. I am going to make it look nice(engine and plumming) when it gets warmer.

[Guest trofeo73]

I road tested it again today and noticed that it started running rough when the hose to the TB fell off. I put it back on and away I was. My transmission shiffts differently now, I am wondering if it has to do with me accidently moving the TV cable. I have a one way checkvalve to my vacum modulator. I did'nt want it to see any positive manifold pressure. I am thinking that may be the source of the soft shifts. Any ideas??

[Guest EDBSO]

Get that transmission oil cooler on fast!!!

[padgett]

a) The only 4T60s I have seen shift firmly are Pontiacs however it is a <span style="font-weight: bold">vaccuum</span> modulator. One way valve amy be holding a vaccuum unless you have a port also.

Please explain the rubber hoses and the thingie where the two come together near the strut tower.

[Guest trofeo73]

Well....The rubber hoses are the only thing that I could make it work immediatley. The thing near the strut tower is a blowoff valve that is not in use. There is a nipple that needed somthing pluged in so...I thought I would put it to good use. The car is incredibly fast, I estimate 250 hp or near that. The high pitch screek is a real head turner, especially with the import crowd. The only problem now is I cooked my Ac hose from dumping the exhaust too close to it, and the fact that the charge air hose keeps blowing off sending my MAF into a frenzy. The car has that pull in second gear that I only felt when driving my freinds cadillac. I wish I would have done it a little more professionally, but I am on a college budget and its my daily driver(gulp!) I am going to buy another car soon though. The knock sensor is very active, somtimes pulling timmimng back 15 degrees or so. So far I have had no detonation however the coolant temp runs about 10-20 degrees hotter. Oil pressure is not 25 psi instead of 43 at idle, but it jumps to 50 as soon as I hit the throttle. The car is a bit cold natured though, startups being a little perilous. I am glad I finally did it, I have wanted to do it for quite some time.

[Don B.]

Make sure your trans vacumm actuactor is

on the intake side of the turbo.

If on the pressure side it will shift funny.

I've been of the forum for awhile, what motor

are you using?

[2seater]

I thought about a check valve in that line too but it will trap vacuum between the check valve and the modulator causing the line pressure to be low and soft/slipping shifts will probably result. You need some sort of bleed off or remove it and try again. Yee Haw! Any idea of the boost pressure you are seeing?

[Guest Buick Mike]

15º of knock retard is a lot!! I would mess my pants if I saw that on my car. You are likely to hurt something running with that tune. My suggestion would be to start with the basics and add fuel and drop boost until you get NO knock. Then tune from there... adding boost and playing with fuel as necessary. Tune for no knock and anything more than 5º and I'd be out of the throttle. Use only the highest octane gas you can find.

If all you've done is install a turbo with no other modifications to the engine, chances are it may not be happy for very long. Unless properly fed and cared for, turbos have a way of finding the weak link and doing bad things.

[padgett]

First question needs to be "what fuel are you using" ? If 87, I would not be surprised at 15 degree pull back. This is why the supercharged engines are marked "premium fuel only". Even a properly tuned modern engine will show some knock particularly at low rpm/high load. Would also be paying attention to the knock counts - if increasing under normal cruise conditions, I would be concerned.

Unless I am mistaken this is a stock "C" block engine that had a turbo added and not one with the 7-7.5:1 compression usually found on a boosted motor.

Have seen boost-controlled water or methane injection work as a knock suppressor before. Whole idea is to run everything as cool as possible and earlier increased operating temperature was mentioned.

If you want it to live, it would also help to limit the boost. 3-5 psi is probably enough.

For a lo-buck fun job, it sounds very good but not to be surprised if the bottom end goes away. Fortunately 3800s are plentiful.

[Guest trofeo73]

I will look into the check valve idea, I am in the process of running a boost gauge as well. I have the vacum line ran directly to the wastegate actuator, perhaps the actuator is bad or it has a spring set up for more than a couple psi. On my sunbird, when the wastegate solenoid was at 100% duty cyle, it had little more than 2 psi. I may have to open the flaper manually to bring boost levels down. I would say that 15 degress was with my foot in it pretty hard. I am using 91 octane, I am probulbly running more boost than I should, I do not hear any pinging or it cutting out though. I figured 8.5 to one was a safe compression ratio?? I have a rising rate fuel regulator to help compensate for boost as well.

[Guest]

I bet some braided stainless steel hoses would work.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Well....The rubber hoses are the only thing that I could make it work immediatley. The thing near the strut tower is a blowoff valve that is not in use. There is a nipple that needed somthing pluged in so...I thought I would put it to good use. The car is incredibly fast, I estimate 250 hp or near that. The high pitch screek is a real head turner, especially with the import crowd. The only problem now is I cooked my Ac hose from dumping the exhaust too close to it, and the fact that the charge air hose keeps blowing off sending my MAF into a frenzy. The car has that pull in second gear that I only felt when driving my freinds cadillac. I wish I would have done it a little more professionally, but I am on a college budget and its my daily driver(gulp!) I am going to buy another car soon though. The knock sensor is very active, somtimes pulling timmimng back 15 degrees or so. So far I have had no detonation however the coolant temp runs about 10-20 degrees hotter. Oil pressure is not 25 psi instead of 43 at idle, but it jumps to 50 as soon as I hit the throttle. The car is a bit cold natured though, startups being a little perilous. I am glad I finally did it, I have wanted to do it for quite some time. </div></div>

[Don B.]

You need to change the fuel pressure regulator

and the fuel pump to Grand National or 3800 S/C

specifications. That is if you changed the fuel

injectors to one of the above engines and not

just slap on a turbo. BTW O2 sensor in a GN is

located on the exhaust manifold before the connecting

pipe into the turbo, nothing on the down pipe to the cat.

[Guest trofeo73]

As long as I dont' hear knock and my A/F guage is good, I am not worried about adding Gn or sc3800 fuel components. Many expensive import turbo kits utilize ONLY a rising rate fuel regulator. They only run 6-8 psi, which is what I need. Yea, I guess if I wanted to do it RIGHT, I would have had someone customize a block, cam, rods, pistons, trans, ect. The car is paid for, and it is my toy, I could only get 1500 bucks out of it anyway. I would maybee go that route if I was restoring it.

[Guest Gomer]

Well i guess i will have to supercharge my reatta and put some NOS in it 2. that seem to be the only thing not tryed!! lol. not going to happen. well have fun with it while it lasts. WARNING: I have heard that if u don't let the turbo slow down before u shut it off u can squeek it. just a thought. had it happen to a friend. the car never ran right after that. have fun and watch for the fuzz.