How much boost can these motors take?

[baller760]

***How much ABUSE can these motors take?**** CORRECT TITLE
I have a stock 1986 Buick GN running on 91 octane throwing a Code 45 (so it smells like it's dumping straight fuel out of the exhaust), and running 16 lbs of boost. The car will almost always show (except for a couple times less than 1.0 degrees), at the end of 1st and in 2nd gear, 3-8 degrees of knock registering on the scanmaster. Of course I don't keep my foot in it after I see that but I've tested it enough to know that this is what is happening. Also, before I got the scanmaster and had it detuned somewhat who knows what knock I was getting. The most I remember seeing on my car was about 15 or so, before I detuned it and retarded the timeing a bit. Well actually one time from a dead stop only doing maybe 10 mph it showed 30! Car completely buckled. However, I replaced the rear main seal and timing chain not too long ago and took a look at the motor visually at least and checked my oil pan and there was only normal wear. Almost no metal shavings at all really in my pan. And this car is a 108,500 mile stock motor that was never opened before. I also rebuilt my oil pump and my oil pressure is now 25-30 psi at idle where it used to be 5-10. The car runs great and there are no problems and no smoking whatsoever minus that stupid Code 45 that I can't figure out. So my question is, am I just damn lucky this thing is still pulling like nothing happened? Have you guys ever detonated this much and still been okay before? I'm scared that maybe something could be weak in the motor but I don't want to open it up and find out everything is okay and waste money I don't have to. Tell me some of your experiences and thoughts please because I don't know if I want to push too much power through the motor now without a freshening up first. That means no quicker than mid to high 12's.

Oh, and the only thing I want to do but haven't done because I don't know how is a leakdown test to make sure the head gaskets check out. Also, I just found out both of my motor mounts are shot and the drivers side one, the rubber has disconnected from the metal.

 

[QUIP'6']

at that low boost level that knock isnt going to effect it but at 20 plus it will have an effect on bearings and gaskets. do yourself a favor and invest in an alky kit. i am at 25 to 26 psi no knock and 24/21 on timing and my o2's are 800 to 810 :biggrin:

 

[BlackBandit]

What's your combo? What chip, injectors, turbo? Also, what is your base (line off) fuel pressure reading? Need some info if you want help sorting out your issues.

As far as the abuse thing goes there's really only two choices. Run it, or build it. If you've got good oil pressure odds are you're probably all right. Just stop detonating it. Any detonation can kill an engine. I took the mains of an engine detonating at around 14 psi. All stock stuff. The boost has very little to do with how it harms the engine. Sure, more boost will create higher cylinder pressures, which will enhance the effects of detonation, but low boost doesn't stop it from doing it's thing. It'll still take stuff apart for you. HTH. james

 

[baller760]

Car is all stock minus a TA-60 turbo because the original couldn't really be called much of a turbo anymore. I lowered my fuel pressure down a little to about 36 to see if I could get some of the richness going away but it still smells like gas coming out of the car. Throwing a code 45. I replaced the o2 not too long ago with a denso which seemed recommended on here. I did disconnect a line from the evap thing on the driver side near the intake because it had a nasy vacuum leak and the car couldn't hold an idle. matter of fact I still only have about 12 on my vacuum reading at idle. Oh, and EGR is new but not AC Delco.

 

[Dreamcar86]

Car is all stock minus a TA-60 turbo because the original couldn't really be called much of a turbo anymore. I lowered my fuel pressure down a little to about 36 to see if I could get some of the richness going away but it still smells like gas coming out of the car. Throwing a code 45. I replaced the o2 not too long ago with a denso which seemed recommended on here. I did disconnect a line from the evap thing on the driver side near the intake because it had a nasy vacuum leak and the car couldn't hold an idle. matter of fact I still only have about 12 on my vacuum reading at idle. Oh, and EGR is new but not AC Delco.

If your only modification is a turbo then you have other areas that need to be addressed. Starting with a hotwire for the fuel pump, adjustable fuel pressure regulator and larger injectors with a chip to match. Do not take short cuts or it will hurt you in the end. Do you have a scan tool?
Seems to me you are going to go lean before you max out your turbo's potential.

 

[SouthernCal GN]

Looks like there's going to be a new member of the DOTC club !!!

 

[baller760]

Well there is an adjustable fuel pressure regulator and it is hotwired according to the Caspers hotwire kit that is on the car. I don't know what kind of fuel pump is on it though. Injectors are also stock but I think the main reason I can't get it tuned right is because of the Code 45. I don't care so much about racing at the moment anyway, it would just be nice to have a car that didn't detonate anytime it goes above 12-ish psi of boost. I've never raced it because of the knock and the Code 45. I'm just saying it's detonated enough to scare me but it still has great oil pressure at 25-30 and there's no sign of damage from what I could tell when I had it open. Of course I am no real expert.

Now what is the DOTC club? That doesn't sound good. lol.

 

[bison]

With zero detonation pressures of 30-35psi have been run by a few members. Ive run 27-28 psi with the combo in my sig.

 

[bison]

Code 45 is rich exhaust too long. You need to pull your injectors and preferably replace rather than have them cleaned. Id go for more injector depending on your goals. Sounds like an injector is spraying all the time. Not good for cylinder walls. Ill bet your oil is full of fuel also. New injectors and Turbo tweak chip (chip is only $85 and adjustable) should be your next mods before even driving the car again. Block learn numbers should be at or around 128 when idling or cruising in closed loop if the chip is right and there are no other fueling problems.

 

[SouthernCal GN]

Well there is an adjustable fuel pressure regulator and it is hotwired according to the Caspers hotwire kit that is on the car. I don't know what kind of fuel pump is on it though. Injectors are also stock but I think the main reason I can't get it tuned right is because of the Code 45. I don't care so much about racing at the moment anyway, it would just be nice to have a car that didn't detonate anytime it goes above 12-ish psi of boost. I've never raced it because of the knock and the Code 45. I'm just saying it's detonated enough to scare me but it still has great oil pressure at 25-30 and there's no sign of damage from what I could tell when I had it open. Of course I am no real expert.

Now what is the DOTC club? That doesn't sound good. lol.

That turbo is more efficient than the stocker, so it's not suprising that you're detonate at those low boost levels. In effect, the 60 is pushing the same volume of air at 13 psi that the stocker did at 18/19 (or so)- hence, your detonation and problems- the car is leaning out. Lowering the FP only adds to the problem.

Your code problem:

CODE 45
Trouble Code 45 indicates that the O2 sensor is showing a persistently low exhaust oxygen content (rich), despite the efforts of the ECM to decrease injector on-time (thus decreasing fuel delivered). Integrator and BLM numbers may indicate < 128 by a substantial margin.
The conditions for setting this code are:

• no Code 34 or Code 35 (MAF error) present, and
• the O2 sensor voltage remains above 752 mV, and
• the ECM is in Closed Loop control, and
• throttle position is < 2 percent or > 20 percent, and
• the above conditions exist for more than 20 seconds.

Typical causes for this code include:
1) O2 sensor defective or contaminated (if incorrect RTV sealant or too much RTV is used, this may happen)
2) Leaking fuel injectors
3) Fuel pressure too high
4) EMI interference from poor plug wires
5) Evaporative Emission system defect
6) TPS and/or EGR problem
7) MAF sensor reading higher airflow than is actually present

Gotta match the turbo, converter, and injectors to each other- can't just throw parts at the car and expect it to perform. You've got a good turbo- now match the rest to it, and you're good for the 12 (and better )


DOTC- Drive Over The Crank Club

 

[GNVYUS 1]

IMO, these motors don't take as much abuse as many of the import turbo motors can, head gaskets being the one of the weakest links. An Evo just ran an 8.5 with tons of boost with no caps or girdle etc.

But in your case it is most likely a sensor etc issue as it sounds like the car has ran great before on the same fuel pressure settings.

You could have the cam sensor a few degrees out or a timing chain issue etc.

Does it throw the code while idling or only during boosted runs??

 

[baller760]

Ok, so I get new injectors and a fuel pump, turn the boost down a bit, change my oil since you say there is probably fuel in there, and use some Seafoam or GM top Engine Cleaner to clean out the motor again? You said the cylinder walls are probably full of fuel so I should use an engine cleaner right?

Oh, and what size injectors? 42.5's? or 50's? My original goals one day were for mid-high 11's.

 

[Quiky One]

IMO, these motors don't take as much abuse as many of the import turbo motors can, head gaskets being the one of the weakest links. QUOTE]

I disagree...These motors stock are as tough as any motor I have seen. I have pushed 25PSI with 23/21 on 91 octane pump with alky and it is still living.

 

[bison]

Ok, so I get new injectors and a fuel pump, turn the boost down a bit, change my oil since you say there is probably fuel in there, and use some Seafoam or GM top Engine Cleaner to clean out the motor again? You said the cylinder walls are probably full of fuel so I should use an engine cleaner right?

Oh, and what size injectors? 42.5's? or 50's? My original goals one day were for mid-high 11's.

Do not use any cleaner. Just an oil change.

 

[baller760]

I'm just worried I don't have anymore lives left with this motor. I mean, everything is a-ok right now, although I should run a leakdown test to make sure. So, my question is, if nothing has happened yet but it has detonated quite a few times to those levels of 6-8 degrees, is the motor weaker in any way because of the stress on the parts? Meaning, if I were to get her dialed in now and end up turning up the boost with an alky kit etc looking for 11's what are the odds of it being able to take the power?

 

[baller760]

IMO, these motors don't take as much abuse as many of the import turbo motors can, head gaskets being the one of the weakest links. An Evo just ran an 8.5 with tons of boost with no caps or girdle etc.

But in your case it is most likely a sensor etc issue as it sounds like the car has ran great before on the same fuel pressure settings.

You could have the cam sensor a few degrees out or a timing chain issue etc.

Does it throw the code while idling or only during boosted runs??

It throws the code while idling once the engine warms up a bit and it never goes away.

 

[bison]

IMO, these motors don't take as much abuse as many of the import turbo motors can, head gaskets being the one of the weakest links. An Evo just ran an 8.5 with tons of boost with no caps or girdle etc.

Its true that the block was never meant to be pushed as hard as a lot of us on this board push it but dont be fooled, The engines in those import cars are not 5 or 6 thousand dollar engines either. At least $15k just on the engine to run those numbers and a lot of them run a % of methanol to run the high manifold pressures they do and most weigh less than our heavy non aerodynamic TR's.

Its just as expensive if not more as building a stage 2 which has been run in the 6's way back in the mid eighties before anyone even thought of imports in drag racing. No head gasket problems on those engines with all the bolts and thick decks they have. Many guys on here are running 650+whp on the 109 blocks that throws them in the 9's at 3500 lbs. Not too bad for 20+ year old junk. If the Champion block debuts soomn expect a lot more radical efforts from a lot of the members on here including me. If not that then a blown LS motor will get it done for me easily :biggrin:

It boils down to one thing:
very fast= very expensive

 

[bison]

It throws the code while idling once the engine warms up a bit and it never goes away.

Sounds like a bad injector for sure. Could be a bad ecm injector driver also.

 

[bison]

I'm just worried I don't have anymore lives left with this motor. I mean, everything is a-ok right now, although I should run a leakdown test to make sure. So, my question is, if nothing has happened yet but it has detonated quite a few times to those levels of 6-8 degrees, is the motor weaker in any way because of the stress on the parts? Meaning, if I were to get her dialed in now and end up turning up the boost with an alky kit etc looking for 11's what are the odds of it being able to take the power?

At your power levels id be less worried about a little detonation. Take car of it before you turn it up. If need be inspect the upper halves of the rod bearings. If its been detonated really bad the bearings will show it.

 

[baller760]

Ok, well I know I gotta get injectors as my next priority after I rebuild my suspension. Now checking the rod bearings means I have to try to take that damn oil pan off again huh. That thing is more trouble than it's worth to get off, lol. If there weren't so many wires that I didn't know where to put back to I would just pull the damn engine and make my life easier, lol.