Hi !
Last week I found out that the "original 198ci engine" in my Duster is a 225... man I made a long face.
Goodbye 2.2turbo piston plans, I have to find a new way to make that car run. What about a turbo 4000maxRPM, torque monster engine? . I have 3 pairs of 45mm throttles, with injector bosses. I´ll make a manifold for them. ECU will be homemade. ECU controlled static ignition. I have two cylinder heads (72/78), a truck and a pass.car exhaust manifold.
1 what kind/size of turbo should I use? Biturbo?
2 it´ll have custom pistons, what compression should I go for ?
3 will the stock exhaust crack at turbo heat? truck or pass.car exhaust?
4 with ported head/bigger valves: what cam ? I know that turbocharged engines have relatively mild cams, will the stock cam do ?
5 I have a std and a truck (bigger) oil pump. Will the stock unit keep up with the demands of maybe 2 turbos and oil-spill piston cooling ?
6 what spring pressures should i use ? There may be high turbo boost but only mid RPM.
Also, i found all pushrods and all valve springs of my two engines to be bent. The pushrods only a little but all of the valves were "slanted" between 7 and 12 degrees. How straight should the pushrods be to be reused ? If I roll them on a mirror I can see a little up and down but I have to get really close to see.
Thanks in advance and have a nice day!
Christian

If you don't need high RPM, a single turbo off a medium sized four banger would do, and could possibly be good for up to 400 lb-ft of torque and 300 hp. If I had started my turbo project from scratch, I would go with one from a Saab or Volvo. They're common in my area, and much easier to remove than the turbo on a 2.2/2.5 Mopar.
It should work with the stock compression ratio.
The manifolds are the same, and how long they last has been the subject of considerable debate. Some say they can't take the heat, others say they can.
You'll get more performance with the Mopar Performace "17 second" cam - which on a turbo car can make enough power to hammer an A-body into the 13's at least. This cam has about the same duration as stock but more lift.
You don't need twin turbos for an engine that doesn't spin past 4,000 RPM. The stock pump will do just fine. Many of the stock replacement parts on the market now are actually high volume units anyway.
I'd use a brand new set of the same sort that go with your choice of cam.
If you can tell it's bent, it shouldn't be reused.

_________________
"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Thanks for your reply, Matt.
My plans are to keep the CR below or at 8.0:1 because of the high boost. I find the dimensions of the turbo is the hardest thing to figure out. Will a medium turbo be able to provide high boost at low to mid rpm? Or will I have to combine a specific turbine size with a specific compressor size ?
I´ll see if the exhaust manifold holds up if it breaks I´ll have a spare one.
I have two late 70´s cams and last year I bought the mopar 16sec cam. I´ll try the stock one first then swap the 16sec cam in to see which one suits my needs best.
Oil pump: I read the article about oil pump gear failure so I don´t want to produce more stress here than needed. If the stock pump provides enough oil pressure I´ll keep it.
Clearances: Should the clearances in the rod and main bearings be tighter than stock to get the oil pressure up ?
What kind of head gasket should I use? Is the stainless marine gasket still available ? Or do I even have to use O-rings and a copper gasket ?
Any ideas welcome !
Christian

Ok, how much boost do you plan to run?!? You can probably get away with 7-8 psi on pump gas with the stock compression ratio, and that's enough to make around 400 lb-ft of torque with a well chosen combination of parts.
There are some excellent books on turbo sizing, and it's not a topic easily covered on a message board. However, if it's good for 2.5 liters at 6,000 RPM, that's not too different from the airflow demands of 3.7 liters at 4,000 RPM.
No. This will cost you horsepower, possibly increase wear, and probably won't raise the pressure, which is controlled by a regulator when things are working correctly. If the stock pump can't keep up with flow demands, you need more volume.
No experience here yet, but I don't see why you shouldn't be able to run a Fel-Pro rubberized gasket.

_________________
"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair