How much boost can it take?

[trevorcwormald]

This is what I have. 83 4D55 approx. 30,000 mi. since rebuild with oversize pistons, undersize mains and rods. Balance shafts removed with full engine balance, flywheel and HB. New AMC head with new roller rocker set installed 10,000 mi ago, rebuilt 84 turbo with 84 exhaust plus intake. EGR is blocked. 84 injection pump, static timed. Engine made 10-11 psi with wastegate connected. I drive 60 mi. to work at job in desert. From sea to 4100 ft. Long climbs take speed down to 50mph at 10-11 psi. Flat sections of road I go above 85 steady even at 4100 altitude. Boost 10-11 psi. Truck is 4x4 with 30.5x15 tires. I have intercooler from eclipse GSX routed to battery area and back to intake. Also fabbed fan shroud. Truck temp gauge maxxed at 3/4 hot at 105 outside temp with a/c on. I disconnected wastegate signal hose and made 15psi, speed went to 57 at steep climbs. Then I removed stock exhaust and added 2 1/2 inch straight pipe. boost went to 18psi with wastegate still disconnected. And I blew my blowoff valve. It would bleed off in puffs at 13psi. I had another blowoff and put it on. And now im back to 18psi. Im worried about breaking something more expensive. I don't have another blowoff, But could get hi performance one to replace it. Would like to keep 18 but anybody Know what my risks are?

[Wardcolorado]

I would think that the big question would be EGT's.... any idea what those are running?

[camoit]

Scan through this post. Not sure how far he got. http://www.mightyram50.net/vbulletin/showthread.php/608-My-4d55-performance-build

[trevorcwormald]

No gauge for EGT
This is what I have. 83 4D55 approx. 30,000 mi. since rebuild with oversize pistons, undersize mains and rods. Balance shafts removed with full engine balance, flywheel and HB. New AMC head with new roller rocker set installed 10,000 mi ago, rebuilt 84 turbo with 84 exhaust plus intake. EGR is blocked. 84 injection pump, static timed. Engine made 10-11 psi with wastegate connected. I drive 60 mi. to work at job in desert. From sea to 4100 ft. Long climbs take speed down to 50mph at 10-11 psi. Flat sections of road I go above 85 steady even at 4100 altitude. Boost 10-11 psi. Truck is 4x4 with 30.5x15 tires. I have intercooler from eclipse GSX routed to battery area and back to intake. Also fabbed fan shroud. Truck temp gauge maxxed at 3/4 hot at 105 outside temp with a/c on. I disconnected wastegate signal hose and made 15psi, speed went to 57 at steep climbs. Then I removed stock exhaust and added 2 1/2 inch straight pipe. boost went to 18psi with wastegate still disconnected. And I blew my blowoff valve. It would bleed off in puffs at 13psi. I had another blowoff and put it on. And now im back to 18psi. Im worried about breaking something more expensive. I don't have another blowoff, But could get hi performance one to replace it. Would like to keep 18 but anybody Know what my risks are?

[4D55 Performance]

No gauge for EGT

Before you touch anything you need a pyrometer. Also boost is a tricky thing and it is all relative to size of the turbo.

[trevorcwormald]

I blew the oil seal on the turbo. Still driving now with wastegate connected. Smokes and smells bad. I ordered new turbo off the internet. Ebay keyword 4d56 1st one that says it fits 84 and is oil cooled. Im sure its Chinese. I'll slap it on and use while mine gets rebuilt. I wanted water cooled but I need plumbing hardware for it. Also im looking into getting a pyrometer before I boost higher. Where did you install it? can I weld a threaded bung on the exhaust pipe right after the flange? Or is that too far away from the turbo? How hot is too hot?
Before you touch anything you need a pyrometer. Also boost is a tricky thing and it is all relative to size of the turbo.