UnrulyNFS

I bit the bullet and went for twins. Best thing I ever did. As far as drive pressures, the BD twins don't have much of a problem with it Their designed to keep that fairly in check. OR SO I've been told. Guess I need to hook up my other boost gauge and find out.

I don't get my egt's above 1200 unless I'm just being stupid and overfueling it for the smoke effect.

cquestad

There is LESS drive pressure with properly designed twins.

There is a larger effeciency range (MAP) with properly designed twins.

They cost more...lots more.

Got money...get twins.

kantdrive55

I know of a twin setup that contrary to what some of the competition says at 40psi has a ratio of about .86 to 1 and at 60psi is 1 to 1.....

metal_miner

I measured my BD twins at 1:1 up to ~60 psi boost.

For blazing around town and towing the BD's can't be beat due to no lag, no surging, and no heat issues! They are perfectly matched in that the "big" primary turbo is always "on boost" and at any time the boost contribution from the Super B and primary are about 40/60 to 45/55 split. At 55 psi, the primary is putting out about 30 psi and the Super B about 25 psi according to my gauges. Both turbos are just loafing along.

If I didn't get such a great deal on the BD's, the Idaho CTD twins would be my next choice. Proven performance as well as supporting the local economy 4 hrs drive away!

The only things I didn't like about twins versus a single were the initial tuning and tinkering time, blowing boots off, and chasing exhaust leaks (the BD primary turbo mount sucks in that the metal sags over time and causes the exhaust connection to be tweaked). After all this was taken care of, they are pure pleasure.

Finding a good air filter also is a chore. With high boost, everytime a boot blew off engine oil was sucked past the primary turbo seals into the intermediate pipe. The high boost with restrictive air filter also kept on pulling oil off the AFE air filter on the primary turbo compressor no matter how little I oiled the filter. I have one of those big oval Amsoil dry nano filters on now so I'll see how that works.

The other drawback with these twins (and twins in general) is that they cost some HP to "drive" them over a big single. I've dynoed before and after twins at same box levels and the twins cost about 10-15 HP to drive them (cquestad was there!). However, at high fueling levels you get more air to clear up the wasted power (smoke and heat) and therefore your power is probably more useable and sustainable.

O.T

JS,

Excellent feedback,

jwb600

a while back someone posted an add of an auction not naming the place but the bd twins kit was reasonably priced around 3200 maybe, earlier this winter and I was thinking real hard about it. now they are 4800 around in there and theres no way I can do that. If I could get a deal on them I would do it.