picked up a cheap 15g turbo that i want to swap on to my 740. anyone know of any issues or some tricks to make this easier, ie. oil lines, reclocking, vacuum lines etc. i have also notied that my turbine section that bolts to my manifold have bare studs facing me. how that hell does this come off? manifold before turbo? any help is greatly appreciated

 

Although you do not say, it's obvious you have an 89 or older 740T. The exhaust manifold has to come off to pull the turbo. You can remedy that for the future by swapping in a 90+ turbo exhaust manifold. They mount with nuts on the outside so future turbos can be pulled w/o pulling the manifold. The new style manifold will also net you a nice 5 or 10 more horsepower as it flows much better. Depending on the year of your 740, you will either have the T3 Garrett or the Mitsubishi turbo. There are some differences if you have a T3. The T3 has an external CBV mounted to the intercooler piping whereas the Mitsu's have an integral CBV. The 15g will need to be reclocked, which is just tedious. While it is apart, it's a great time to rebuild it. Not nearly as daunting as it may seem. The cheapest, best and most helpful parts supplier I've found is
G-Pop Shop If needed, they will walk you through it via email.
Things to keep in mind when swapping turbos: 1. The oil supply line is model specific; any turbo other than factory will require some ingenuity. 2. Swapping to a 90+ manifold may require milling the mounting flange 3. The oil drain tube too will need some modification.
4. If you are swapping from a T3 to a Mitsu, something will need to be done with your hot side i/c piping that has the CBV mounted. Generally, the simplest thing is to buy the appropriate piping from a newer 740.
These swaps are done a LOT...so don't hesitate to tackle it...but don't try to re-invent the wheel. Scoot over to turbobricks.com and do a search. Lots of write-ups and step by step build threads.

 

my car is an 88, and i am also picking up a running 90 tubo sedan for a parts car for $300, so i can pass it up. the 15g i picked up is from a 94 850, tag says volvo, but made in japan. as far as the oil feed and drain line go, do the fittings need modified? or should i just get all new lines custom made to my specs? i would like to see some specific pics of this swap, ive rebuilt and worked with turbos a lot before, but its was on aircooled arcraft motors, not volvo model specific.

 

OK...your car has a Mitsu 13c most likely. Whether those two have identical oil lines I don't know. I really don't have anything against Mitsu's...just favor Garretts because that's what I started with and have stuck with. Volvo made the switch to get a smaller, faster spooling turbo to please Americans used to instant power from V8's. Spool has never been an issue for me so I stayed w/ the larger Garretts. Again, check out TB for specifics on the swap...it's your best resource.

 

thanks for the pointers