Turboed A20A1

[ccotm]

How much boost will an A20A1 carbed engine handle? If any?

[A20A1]

Stock?

5-7 PSI

Thats assuming you've done some tuning with the fuel and ignition.

[ccotm]

Would that really make all that much of a difference to the performance?

[A20A1]

A small turbo will spool up quicker and have the smaller boost levels. Probably could get 160-180 hp.






Those are both draw thru / pull thru turbo carb setups.

One sends the air and fuel mix thru the rear of the intake manifold. The place where the carburetor normally sits is covered with a plate so that the aur fuel mix does not escape.

The last pic sends the air fuel mix thru the top of the intake manifold, thru the same hole that the carb used to sit on.
When doing draw/pull thru turbo the carb is relocated to where the turbo is... it site on a 90 Degree elbow that takes the air fuel mix from the carb to the turbo and from the turbo to the intake manifold.

You'll porbably have to do your carb turbo the same as they did it in the last picture... You must be very careful though, you cannot have too many bend in the pipe that runs from the turbo to the intake manifold... you should try and make the distance from the turbo to the manifold as short as possible.

you may be able to relocate your turbo to the right or left side of the engine if it is small enough... then you can run an exhaust pipe off your stock 4-1 cast iron manifold to where ever you place your turbo.

[FyreDaug]

^^ Which unless you have experience in such setups I would not suggest trying it. Start off with a fuel injection swap. Cheaper, and will take about the same amount of time to set up, except in this case, youll gain power AND milage.

[ccotm]

what kind of things would i need to convert it to fuel injection?

[A20A1]

This
https://www.3geez.com/forum/showthread.php?t=112

or

This



That was my other option for turbo placement.
I would run the pipe from the 4-1 manifold under the oilpan how it is stock, but then route it back up between the motor and the firewall to the turbo. I like it this way because there is less distance between the carb-turbo-manifold-head.

I think the lower boost levels is good for Draw/Pull thru turbo... if you want more boost you might consider swapping to EFI or doing a blow thru turbo with intercooler.

Since you're not running that much boost you can try
1 step colder then the stock EFI NGK plug.
2 steps colder then the stock Carb NGK plug.

You'll want to look into ignition control, though I'm not sure what works and doesn't work without an ECU.
The two things I was looking at when I wanted to try pull thru turbo were the MSD BTM which doesn't need an ECU and J&S Safegaurd.
Also I was told to lock the mechanical advance inside the distributor or restrict how far it moves.

You'll want a wideband O2 sensor and gauge. There is a delay in the reading so take that into account when you tune the carb jets.
Carb tuning would pretty much rest on jets and the fuel flow settings. If you were to go blow thru you'd have to seal the carb throttle shafts and make the carb air tight, modify the float to handle boost pressure so it doesn't crush, modify the powervalve, have a boost sensitive fuel pressure regulator, a fuel pump to handle more then the max psi the adjustable fuel pressure regulator will reach under you max boost setting, etc.

I'm not sure what is a better carb for turbo, Progressive or Synchronous but my plan was to swap in a 38 or single 45 or 50 DCOE which are all synchronous carbs. Synchronous meaning both throttle plates open at the same time instead of progressive which opens the throttle plates at different times.

I would have started at 5psi and then work my way to 7psi.

You should do a compression check of your engine before you even consider boost, if you need to rebuild it, you'll be much happier.