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Just a few of my thoughts,questions, and opinions:
1) You have a rare Corvette. You can hop it up, but it just takes a bit more thought when boost is involved.
2) As was mentioned earlier, put a wide band O2 sensor on it. You don't want the uncertainly of what your A/F ratio is under boost conditions.
3) Ask Lars for advice on tuning/modifying your QuadraJet. I have zero QuadraJet experience, so I can't offer up any technical advice there.
4) Does your system have a boost wastegate or just a pop-off valve?
5) Does your intake manifold have any bypass valving in the plenum to shunt the compressor section during low load conditions (this helps low speed driveability)? I put a Martin Turbosystem in my '84 several decades ago. It has reed valves in the plenum to shunt the turbo at light throttle, and it drives like a normally aspirated engine at low speeds.
6) What is your present ignition timing curve (ie: does it retard the timing as boost is built)?
7) Also as mentioned earlier, make sure your exhaust system flows well. You will have unavoidable backpressure between the exhaust port and the turbine section inlet, but you do NOT want additional/noticeable backpressure downstream of the turbine section.
8) For now I wouldn't worry about big engine mods. Your present engine ought to be sufficient for a while yet. Years ago IIRC Dave MacLellan (sp?) mentioned that higher RPM centrifugal loads are harder on the pistons and rods than moderate boost levels. (I welcome correction if it was someone else.)
9) Lean fuel mixtures or spark knock are to be avoided like the plague.
10) Consider using a touch smaller plug gap to deal with the boost, as you don't want any misfires out the exhaust or into the compressor inlet section.
That's about it off the top of my head. Have fun, but be prepared to do some reading about turbocharging, as most of your car/beer-drinking buddies won't be of much help.
2, I order it and definitely I will put in to car A/F gauge
3, We will see, I am from Europe unfortunately
4-5, Is some possibility you have some picture or something like that? I was looking everyhwere eithout succes...
6, Any anvice is welcomed, I am in studiing phase about distributor curves
7, only 3inch tube and 2 stainless steel mufflers.
9, It is scares me pretty big - A/F is ordered
10, Consider using a touch smaller plug gap - Can you explained it to me more please? Smaller gap in spark plug will be any influence on it?
Well the first thing to do is get rid of this miserable thing.....
And if the cat is still on it.....get rid of it too......first two things. A deliberate intake and exhaust restriction......with a turbo in the center of it......probably the worst thing you could do......and the heat! Heat is your enemy here and was the enemy when this car was in development from ACI.......so many little things that can be done to improve performance.....
Jebby
Jebby can you tell me what is purpose of this thing with 2 big wires ? I understand I have stupid maybe easy questions, but I am really new in this things about boost and engine performance. And here in Europe aren´t lots of parts and knowledge around...
Jebby can you tell me what is purpose of this thing with 2 big wires ? I understand I have stupid maybe easy questions, but I am really new in this things about boost and engine performance. And here in Europe aren´t lots of parts and knowledge around...
It is a heater grid for cold startups......an emissions control device......not only does it disrupt flow, it is heating the air.....which is a killer for turbos.....Heat=Bad. A standard L-82 350 Q-Jet carb gasket will work well here....
The engine is trying to pull fuel in via vacuum.....and at low speed it is pretty horrible on this setup......everything you can do the have the vacuum "see" the booster and draw fuel from it......anything in the way is a hinderance,
Ironically, the 80'-81' Trans Am turbo suffered from much of the same perils as this car when built but had an even shittier engine and small *** turbo.......a great freakin car straddled with a half baked engine......in the early 90's a neighbor had a 81 Trans Am Turbo with a 455 SD engine swapped in it....rest of the car was bone stock and immaculate.....that was one Bad *** car......and this Vette can be too.....
Yeah, the 301T cars had the looks, comfort, and handled well, but power wasn't their strong point. Still, with some carb tweaks, wastegate mods and meth injection, you can get em to run pretty hard nowadays.
Yeah, the 301T cars had the looks, comfort, and handled well, but power wasn't their strong point. Still, with some carb tweaks, wastegate mods and meth injection, you can get em to run pretty hard nowadays.
Yes, they can be fixed to run pretty well.......you can gain 1 whole second in the 1/4 mile by deleting the cat, removing the hot coolant plumbing from the plenum, deleting the EGR,and twisting the adjustment on the waste gate.....all free stuff or less than $100.....the early Turbo Buick 3.8l had the same exact turbo unit and housing......those cars responded to the same mods......I had one when I was 16.....my second car.....did all this stuff to it and it was like a different car.....I eventually hurt the engine LOL......
It is a heater grid for cold startups......an emissions control device......not only does it disrupt flow, it is heating the air.....which is a killer for turbos.....Heat=Bad. A standard L-82 350 Q-Jet carb gasket will work well here....
The engine is trying to pull fuel in via vacuum.....and at low speed it is pretty horrible on this setup......everything you can do the have the vacuum "see" the booster and draw fuel from it......anything in the way is a hinderance,
Jebby
If there is no low-load airflow shunt in the plenum (and it currently appears there isn't), removing the grid heater is likely going to cause serious driveability issues during cold startup due to fuel condensing/pooling in the cold compressor inlet tubing. I assume the heater eventually shuts off when the engine reaches operating temperature, so the heating is not an issue during regular driving, and I suspect the Qjet secondaries are capable of supplying sufficient airflow for this setup, so the primary grid restriction shouldn't be a show stopper.
If there is no low-load airflow shunt in the plenum (and it currently appears there isn't), removing the grid heater is likely going to cause serious driveability issues during cold startup due to fuel condensing/pooling in the cold compressor inlet tubing. I assume the heater eventually shuts off when the engine reaches operating temperature, so the heating is not an issue during regular driving, and I suspect the Qjet secondaries are capable of supplying sufficient airflow for this setup, so the primary grid restriction shouldn't be a show stopper.
But it is right under the primary.....right where you drive most of the time.......and disrupts the signal to the booster, which makes it lazy off boost......I have removed them on many different applications including the Buick turbo......with no ill effects, and I lived in Michigan at the time......another bonus of the heater grid is that sometimes they can stay on which melts the grid and goes right into the engine, of in this case, the turbo inlet.....
my pea brain doesn't get how adding air below carb even works?
It's a two story plenum. The carb feeds the second story and also the compressor inlet tubing. The compressor outlet feeds the plenum ground floor and the intake runners.
my pea brain doesn't get how adding air below carb even works?
You're not adding air below the carb......the plenum that he carb sits on is the inlet and outlet......inlet is the front chrome tube and the discharge is in the back....just below the carb is a wall that divides the two.....the air goes through the carb and makes a hard 90 degree into the turbo.....it really is a goofy design to be honest.....LOL.....flows like ****.....
But it is right under the primary.....right where you drive most of the time.......and disrupts the signal to the booster, which makes it lazy off boost......I have removed them on many different applications including the Buick turbo......with no ill effects, and I lived in Michigan at the time......another bonus of the heater grid is that sometimes they can stay on which melts the grid and goes right into the engine, of in this case, the turbo inlet.....
Jebby
This compressor inlet tubing on his engine is about a foot long. That seems substantially different/longer than the short port routing between the carb and turbo inlet on the early GM carbureted turbo systems.
Fortunately for the PO, it's a low cost experiment to remove the grid heater and insert a simple carb gasket to see if his local climate will allow decent cool weather driveability sans heater.
Regarding a possible thermo structural failure of the grid, I share your concern.
pics of the entire car. IIRC the nose had built in monza headlights and the hoods had a NACA inlet on them also.
IF this is a true Duntov Turbo car, leave it stock for the future BJ auction roll.
This may shed some light on your engine specs. Looks like Chevrolet experimented with a turbo Corvette and used an L82 engine with an L48 cam. Which might have led to the confusion of whether it was an L82 or L48. I have no idea if this is the case with your car, but it is interesting.
Jebby, that sure as hell looks like an 82 corvette knock sensor on that manifold? What year and make again?
I saw that too...LOL......1980-81' Trans Am Turbo. You may want to look at 78-82 Turbo 3.8l Regal/Rivera/Century/Monte Carlo.....it had a very similar engine "control"....
01-30-2024, 08:12 AM
