Currently I'm diagnosing a DC4 B20B turbo build that blew the engine. Smokes like crazy once it is warmed up.

This B20B has very low compression numbers on the compression test. 150 140 160 150 after oil added to the cylinders. WIthout oil the numbers are 115 110 125 125. All numbers w/ throttle plate wide open.

Car will idle and move but smokes very bad and we have to keep revs very high to move the car on any incline.

We are going to swap this engine out but just seeing if anybody has any insight as to whether it's the piston rings, valves, head gasket or all the above. Also I will probably be back in here as we decide whether to build our b18 block or rebuild this b20b.

Thanks in advance.

 

Leakdown rest is the only way to completely tell u what’s wrong. But if u added oil and compression test jumped more than likely needs rings

so rebuild short block. Well longblock

will cost you probably $400-800 to rebuild long block if oem vs cheap parts

 

Have to keep revs high to move on an incline? Sounds like you have other issues I'd look into before doing engine work.

If staying boosted, use the b18 block.

 

Thanks for the reply. That is definitely one option we are looking at.

 

Thanks for the reply. What is your guess about what other things could be wrong?

Engine will idle (and smoke) for as long as we need it too. We can rev the engine to 7k if needed. The car will drive around on flat ground. As soon as we go up the incline to the garage, it will bog and die out if we engage the clutch under 3k or so rpms. So we are assuming the engine compression numbers being so low, the after market clutch is basically slowing down the flywheel to the point where the lack of compression cant overcome the friction.

What are your thoughts?

 

Hmmm...
If this is true, engine seems to be struggling under load. Could be a couple issues. Primarily TPS/MAP sensor related; fuel delivery, etc., but if you've got a failing cylinder, this won't really help matters much either. Lol! Usually old rings will eventually heat and expand, causing the startup smoke to stop. Valve stem seals will usually cause smoke all the time, particularly after the engine is running under vac at higher rpm then given the throttle; i.e. coming downhill at about 3k rpm for a few seconds. You'll REALLY notice then. If the seals are bad enough, it can smoke constantly.
Rings, maybe.. Valve stem seals, maybe. Gunked valves not seating properly due to bad seals, maybe. Headgasket, maybe. Several possibilities here.