1978 231 turbo 6 build

[techg8]

OK I got it up and running today!

I jumpered out Turbo control center for the time being. I will add that back in as I tune things.

I ran it for 20 minutes between 2250 and 2600 rpm and encountered no bad effects. Here is a 10 sec video of the break in.:

 

[techg8]

I checked the calibration of the quadrajet, its a stock 79 Turbo carb built by Everyday Performance LLC.

I had a little trouble with the PECvalve because I had it hooked up wrong, screwing up the power enrichment. But I got it figured and operating correctly. So I re-tuned the idle mix.

The car runs and drives great. I do hear some detonation under boost but will work to tune that out.

I need to adjust the wastegate - at one point I saw 12lbs boost. More typically I am seeing 10lbs.

Maybe I am used to V8power, but the low end seems a bit sluggish. Until the boost comes in, then it feels at least alive if not fast.

I have 2.73 gears in the rear now. Any opinion on going to 3.08s or 3.42s? (I need to posi the rear as well)

I installed the Turbo Control center and just need to figure out what the ESC relay is supposed to do, then head to radio shack and get an appropriate relay. Then the knock retard system will be in action.

For the future: cold air intake via a chrome turbo6 hat OR a scoop in the hood...undecided...some kind of water/alky injection to help stop the detonation.

a pic as it stands now...

 

[techg8]

I adjusted the wastegate actuator rod and brought boost down to 7lbs - I see a spike to 10lbs on some shifts, but the car is much better off.

Previously it was over boosting (I saw a quick 15lbs...whoops!) and I would have to get out of the gas quick because of the detonation. I dont want to break anything.

So at these boost levels it doesnt audibly detonate much, and I can stay in the throttle WOT.The car feels a lot better now that I am confident of the boost settings.

On the ESC setup, I actually found the appropriate ESC relay #3996204 on ebay. The GM original was going for like $35 but I found a Littlefuse version for about $10 so I bought two. Should be here in a few days and I can try to get the ESC working.

I like the way the car feels when at WOT. And I am sure I will be able to get more boost in there with some anti detonation mods.

But it is a little sluggish off the line with 2.73s in the rear.

I am thinking that 3.42s may be in order. 3.08 just wouldnt be that much of a change from 2.73 I think. I would welcome anyone's opinion on gear ratio selection. thanks

 

[MNcarbturbo]

I had 2.41 and went to 3.42's. It wasnt that much different honestly. It didnt build boost before 20mph before and still doesnt. Im pretty sure id need a higher stall in the converter. Its a lot better from 35 up. Runs a little high rpm on the road, not horrible but i wouldnt go forever without a overdrive.

 

[b4black]

Buick went to 3.08 in 1982 with the 3-speed 350c and then 3.42 in 1983 with the overdrive 200-4r.

I think they are always going to be sluggish off the line with this turbo configuration.

 

[techg8]

Thanks for the input

Well I will keep on trying to improve what Ive got via tuning before adding anything major. With the 3 speed trans I will probably only go to 3.08s in the rear.

I am not currently running any vacuum advance because the can is no good. I suppose/hope that might add a little part throttle pep.

Once I get cold air and an alky setup on it and get the timing squared away to build some more boost without detonation I will have to try launching off the footbrake some.

 

[techg8]

I cut away a little of the underside of the hood and tried on the V6 carb hat. its close but seems to fit.

I am not sure If I will stay with this setup for cooler air. I was also considering using an Edelbrock pro flow - one of those triangle shaped foam filters - and cutting the hood for an off-center cowl or a forward facing version right above the carb, like a scoop.

 

[techg8]

Received my ESC relays and installed one.

I was pleasantly surprised that the car fired right up! I was kind of expecting a smoking wire harness for some reason....

Anyhow I tested the knock retard with a long extension tapping the intake, and IT WORKS GREAT

I am very pleased with this result.

I need to tidy up the install a little bit, then I will snap a pic and post it. Maybe grab a video showing it in action.

 

[b4black]

Awesome! Good work. Glad to see it coming together well.

1980/81 Monte Carlos had a bolt on hood bump. They are hard to find, but that might be an option.

 

[MNcarbturbo]

Ive got a monte turbo bump laying around if your intetested

Sent via a potato with the sour cream and shredded cheese app

 

[techg8]

I like the idea of that bolt on turbo scoop, but I dont know a thing about them. Are they functional or decorative? have a few pics MNcarbturbo?

Ive got a short video of the ESC system working. I nopte that when I drive around, I can feel it pulling timing when boost is between 8 and 10 psi. It certainly kills the power.

I also ran into two small problems with the car. The old Ignition module started intermittently cutting out. It would run fine then just stop. Seems like the old module was overheating inside or something because it would come back once cooled. Anyhow, I replaced it with the new one I have.

Also, the used water pump that had "appeared" to be ok has now begun seeping out the weephole. I guess I will be replacing that.

 

[MNcarbturbo]

 

[b4black]

They are decorative. On the 1981 Monte, they are just bolted on with no hole in the hood. If you having clearance issue, I'm sure you could cut a hole and cover it with this. If you 're looking for functional, then I don't think this would be useful. Even if you cut open the back, it's not very tall.

 

[b4black]

I note that when I drive around, I can feel it pulling timing when boost is between 8 and 10 psi. It certainly kills the power.

When they knock, they overcompensate. They pull too much timing and then bring it back very slowly. But it beats blowing a headgasket. Modern engines are are designed to allow a little knock and then pull back just enough timing for optimum fuel economy.

The way to approach it is to not knock at all, but if you do, you have a safety net. On the later Turbo V6s with an ECM, you can run a knock gauge to see what's happening. I'm not sure how to do that on a early non-ECM set up, but I'm sure there is a way.

 

[techg8]

The way to approach it is to not knock at all, but if you do, you have a safety net.

Yes that was my thought as well.

So am I getting it right that the way to minimize detonation is in the timing and adding alky injection to cool the A/F charge?

I can richen the carb up a little if that might help.

 

[b4black]

Yes, you're on the right track. Lower boost, retarded timing and richening up the secondaries are all ways to minimize knock. Alcohol injeciton is another, but can be be a little tricky to balance out just right.

Of course running premium gas is a must. Your engine was built before unleaded premium was avalable. All the road tests of cars back them noted knock issues.

And then you can have "false knock" on the motor is flopping around a the downpipe hits the frame (or something similar). Run some race gas once in a while and see if the knock goes away. If it's still there, then the 'knock' could be false knock.

 

[techg8]

I ordered a crane adjustable vacuum advance from Summit today. I think this might give me a little more pep around town.

I also bought some heat tape so I can wrap the melting wire harness that goes over the center of the intake.

I went to DA secondary rods - they had a fast enrichment profile like the stock CPs, but with a smaller power tip diameter and a longer power tip length.

I also went thru my pile o parts and found a primary pulloff that opens faster, hoping to get faster secondary throttle response.

I am considering the benefits of opening the air flap open distance a bit more.

 

[charlief1]

The top of the rear valve should open so the front half is straight up. The bottom plates should open to be even with the divider in the center of the bores on the rear.

 

[techg8]

Ive been driving this thing around a little, and have been puzzling over a sort of "dead" spot when I roll into the throttle partway. It feels like a lean spot but playing with the fuel hasnt had any effect.

The power valve I believe to be functioning correctly.

So I got to looking at the timing finally, and found that the ESC is pulling timing, causing a real flat spot on takeoff.or mild accelleration

I plugged up the vacuum advance when testing this.

when I jumper out the ESC I dont see the timing drop on mild throttle application. Mechanical advance comes in smooth and stops at its limit.

When I add the ESC, the system retards timing on mild throttle application. This occurs at about 41 degrees total advance.

Clearly I need to play with the mechanical advance curve and or amount.

Does anyone have any suggestions as to what they have found these engines to favor?

I set the initial at 16degrees, factory.
I am pretty happy with the mechanical timing coming in by 2500rpm
The mechanical takes the total out to 51 degrees with the ESC off and the vacuum advance plugged. This seems excessive to me. What is a good number to shoot for here? From my experiments it seems that the engine knocks at 41 degrees. Limit the mechanical to achieve a total just below that?

Thanks for any assistance.

 

[MNcarbturbo]

Ive ran into the same issue. Motor is good at cruise and not in boost and screems when in boost but that 4" to 3 PSI zone rolling into it seems like a dead spot. I cant get my power valve system to work. At one point I bypassed the PECV since mine was bad. Its good under 8" but real lean anything less until the secondaries open. My power valve isnt releasing even with a good PECV.

I never thought that timing was causing the mid throttle dead spot. Ive got an NA v6 distributor and MSD BTM with no ESC.