Engine/Transmission (1994 - 1998) BD twins

[KAlder]

Is anyone running BD twins with a stock headgasket? If so hows it holding up? I want to turn my old girl up, but my wife needs to tow with it and I don't want to see it coming down the driveway w/ burned up pistons or blown headgasket.

-Kevin

 

[MGarland]

Be safe and o-ring or firering it with a good set of studs.

Mark

 

[KAlder]

I just want to drive the damn thing Don't want to have a ritual of retorque studs, run valves,& bleed the injector lines every oil change, lol. i guess i'll have to settle on less fuel I can get a set of bd twins through work for 2400 bucks. i havent started anything yet, waitin for the sale on my jeep to go through. just want some good power out of her w/o having to be down at work every night wrenchin on it, just to keep it running. What is the normal retorque interval on fire rings or orings?

 

[fox]

The stock head gasket should be good up to 50 psi boost.

Boost is related to the amount of fuel. Hot much are you feeding it?

 

[Jim Fulmer]

I wish people would loose that word (firering) it makes the smaller guy actually think they might have to do that to there truck... ... ... it's more of a headache than it's worth.



FYI, I wouldn't even think about doing it to my truck. I did a single O-Ring in the head in the early spring of 03' and it still has not given me any trouble... ... . zero!



Jim

 

[MGarland]

Jim, how much boost have the o-ring's held and what was the drive pressure?

thanks Mark

 

[KAlder]

I was thinking about a #10 plate and DDP stage 3s or 4s. I was hoping for around 400 horse but it needs to be power that you dont have to watch (my wife will be driving sometimes). It is also my workhorse so it needs to be able to tow w/o EGT problems, that's another reason I wanted twins.

 

[KAlder]

Can you adjust the BDs so they are at 40-45 psi and still work good?

 

[Jim Fulmer]

Jim, how much boost have the o-ring's held and what was the drive pressure?

thanks Mark

At the beginning I ran a small set of Twins 35/3B at 65psi with 72 drive, then later went to a 40/BB and ran at 80 with 85 drive, then to the 66/BB with the same boost and a little better drive. My head was one of the original one Piers did and has a . 051 wire with 18 thousands protrusion... ... that's allot! it requires a little more attention at the beginning to get it set in. Most people now run a 41 or 51 wire but with less protrusion.



Jim

 

[Diesel Nut]

Can you adjust the BDs so they are at 40-45 psi and still work good?

You can adjust it to where ever you want. They should come preset somewhere near the 50# mark. You won't even be working those turbos at the 400hp level and 45-50 psi boost.



Fueling to an extent does dictate boost, but you can override that with the wastegate to bing boost down a bit.

 

[Tom C]

I keep reading about O-rings and Drive. I'm getting to be an old timer I guess. can someone explain those new terms for me? for instance Jim said "later went to a 40/BB and ran at 80 with 85 drive". whats "80 with 85 drive" mean? Also whats a "41 or 51 wire but with less protrusion" mean? I've built a few motors in my time but havent heard those terms yet. .



Thanks in advance for the lesson



Tom

 

[Jim Fulmer]

Hey Tom! What I was meaning is running 80 psi of boost with 85 psi of drive pressure. The 41/51 is and . 041 wire or an . 051 wire, most people now run 10-14 thousands protrusion instead of 18 like mine.



Jim

 

[Hammer]

"later went to a 40/BB and ran at 80 with 85 drive". whats "80 with 85 drive" mean?

40/BB=Hx40 and a Big Brother for a bottom charger.

80 with 85 drive=80lbs of boost with 85lbs of drive pressure(exhaust pressure)

Also whats a "41 or 51 wire but with less protrusion" mean?

41 thousandth stainless o-ring wire with less protrusion means less of the wire protruding from the head itself. Or more easily explained,the o-rings are using a 41 thousandth wire and have the head deeper cut so less wire protrudes from it. Most guys use a 41 wire and leave about 10 out,some go more some go less,depends on the wire and the machine shop.



Mark. .

Most will tell you that o-rings are good up to about 70psi on a regular basis,however,I have also seen some fail at that also. It depends on the driver,truck and how fat he is on the pedal and for how long. Long shots of high boost will usually lead to failure with o-rings.



KAlder. .

Even though your ability to get a "buy" on a set of B-D twins spikes your interest,the money spent there could be better utilized to prep you bullet for them later. While I do also understand that you want them and its your truck,without the addition of o-rings and/or head studs the twins would never perform up to their capabilities. Todays diesel performance market has so many good quality hard charging singles,why coin out for twins when you will never use them up to what they need to be?. A hard charging single will do what you want and allow you the coin for other parts to bullet proof your ride for later twins additions. At one time to make power you needed the twins,with that now not the case many owners have been taking them off for the big singles,Jim is one of those. Just a thought for you to ponder.....



BTW,Just because you have studs and orings or fire rings doesn't mean you will need to retorque at each service. Done the right way the first time a occasional check is all they will require... ... ... ... ..... Andy

 

[NHays]

I am running a BD superB single. I think its comparable to the HTB2 turbo,or something like that. I am unsure about that. However, I use my truck to farm and work with and like the turbo, I run a #10 BD plate that sits about . 045" ahead of stock. its around 400HP. I have the waiste gate set at 45psi MAX. I have had the engine rebuilt and run a new stock head gasket, I have not had the engine ringed or anything. If I really REALLY push the truck with a heavy load and have a boat anchor in the ground, I can get the EGTs a little bit above 1300*, but it takes a little while to get it there. If I full throttle the truck, I am well into the 3 digit speeds by the time the EGTs get hot. I plan on putting a valet switch in the truck so other people like my girlfriend can drive it. Back to the turbo... . I think this turbo has a very usable spool-up. It is noticably laggier than the HX35, but when she lights, you better hang on. I get very good cruising fuel milage with it, but it does cruise a bit warmer than the HX35. I get better towing MPG with the superB versus the HX35, the superB runs a lower boost than HX35 while towing and the EGTs are cooler while towing.