That'* the OTHER contested issue, but not nearly so hot. LMFAO!

Anyway, FWIW, my transmission builder CLAIMS that he'* discovered there'* a difference in the CASE on an HD. He refuses to build my trans on a standard 4T60 core for this reason. If one can't be found from an LSS or SSEi, he'* going with a Caddy unit from the 4.9 Northstar predecessor. That was an 'HD' rated unit as well.

If you guys want Im sure I could get this Reatta owner to post on his engine. I find him to be very informative and knowledgable. Hes not some kid that wants to go fast, he likes his Reatta and wanted some more draft when he asked for it. I know Padget knows exactly who Im talking about. With thses mini AFC'* and hand held diagonstics stuff it might not be so hard to get A/F correct. The timing curve will be the problem. With OBD I the first end of task would be to find out who out there knows how to get into and change the parameters of the system. That with the AFC will cost as much as the turbo and fabrication set up but it must be done first.

Remember there was an aftermarket turbo kit back in the day, I forget now which engine I saw it on LG3 or LN3. theres a picture floating around the net somewhere.

Im sure the L27 is as strong as LN3 but no not forged, not cheap cast mush but not forged.

Till more people start doing this we will never know whats involved. Myself I do plan on doing the LG3-3 I have and putting it in my 86 LeSabre coupe. Thats easier though because you can just use ECM from a turbo Buick. Im not Mr Speedracer though. I just have some fun back roading from time to time. I dont give a hoot about 1/4 mile times or burnouts or racing everybody from some red light. People with that in mind will certainly eat up something, be it transmission or improper pistons. Rods and crank will be fine at 4800-5000 so long as we dont drive there all day long. Your only looking at maybe 210-220 HP anyhow.

Hot air turbo SFI Regal/Riviera engine was only 205-210hp.

Having the Reatta owner post or getting information would help, but honestly, most owners of that generation probably won't do anything with it. And making assumptions from those drivetrains to the L27 would put us right back where we are right now.

Personally, I'm curious to see what he has to say.

what info is out there on when did Gm start using the forged powdered metal rods in the 3800'*? they went to that technology cause it was cheaper to mass produce the rods, however Howards cams now markets high strength powdered metal forged rods for sbc and others that are on par with reg forged rods.
well regardless ya'll be in the loop when me and Al turbocharge the LN3 3800 in the rear of the 94 442 project we will be starting out conservative and when we go to the MegaSquirt DIY EFI we will be able to wick up the pressure and tune for it but the limiting factor will always be the tranny'* and besides i doubt we'd get more than 400 crank Hp reliably-but that is what the two stage boost control is for one for street and higher for the track.
i still cant wait to start playing with the turbo though.....
i'll be keeping you guys in the loop on this one! even if we split the 3800 in two...
James

well a few years prior to the turbo he did a old school hot rod mod and used L27 pistons in LN3 to raise compression to approx 9:1. I know that. Part of the problem with his detonation, obviously.

How much is different in the computers between the LN3-C and L27 ? E tranny ? Whatelse ?

fwiw, i just checked the part prints for these cranks, and found no mention whatsoever of shot peening. anywhere.

and as far as them being the same, i think they are. when i did the part number lookup (for older parts, i have to use gmpartsdirect.com too), i looked up the one part number provided - 24501594. when i looked up the print, right smack in the middle of the page, there was a note that said: otherwise the same as 24501595.

i then looked up that crank, and i haven't been able to find a single difference between the prints.

take it for what it is...

Do the prints call out manufacturing techniques or materials?

And it was the rods that were claimed to be shotpeened, not the crank. For some time it was thought the L67 rods were peened, and that the L27 wasn't. I think we've found since then that they're the same, other than the bushing/pin design.

in cases of machining other than the basic cutting and milling, they're called. for instance, i now know that when they're polishing the crank on the l27 that they need to run the crank in a clockwise direction if you were facing it head on. interesting, no?

anyhew, i'm way out of the loop here! sorry! I'll see what i can see on the other parts later. depending on how recently the sheets were updated, i can tell you gobs of information. new part prints even tell what metal is used, and in cases, what sort of heat treat is used.

I have to thank Steve LS for directing me to this site and sorta paving the way. I read with interest what is being done here and my older LN-3 is way out of date, but maybe some of my experience will be helpful (or maybe someone has a suggestion). As Steve related, the engine was a junkyard rebuild of a vin C, with later model pistons for more compression ratio, old school hot rodding as he called it. Normal stuff, small overbore, hypereutectic pistons, hand porting of the heads, throttle body bored out etc... Air and fuel flow measurements indicated 192-195 hp. While not the best engine to turbocharge,( it would have been better to drop the compression half a number rather than raise it), but the turbo wasn't planned when it was built. The turbo itself is assembled from junkyard parts, primarily a T3 from a turbo Riviera but with the compressor housing from an '83 turbo T'bird, which has a lower .63 A/R ratio. My original engine was hanging on the stand, and I fabricated my own manifolds from three sets of junkyard ones. The rear manifold feeds into the front one through a crossover on the passengers side of the engine, kind of reversed from the normal pattern. The turbo sits pretty much where the stock air box was and was designed as a hot air setup assuming low boost as the goal. The turbo blows directly into the MAF/TB assembly in their stock location. The whole manifold setup and turbine housing are ceramic coated with no heat shielding used. The design of the manifolding is such that the turbo assembly and downpipe can be removed as a unit and the stock crossover pipe reinstalled and it will run as an n/a engine. The fuel system was upgraded to 24# injectors from a Corvette and a Walbro 307 fuel pump. Base fuel pressure was increased to 50 psi for about 26# fuel flow capability. I saw the question about the the L27 injectors being large enough and I do not know what their flow rating is. The base calculation for a boosted engine is approx. 1.75 hp per pound of fuel flow per hour at 100% duty cycle. The engine handles 5-6psi of boost without detectable knock, except in third gear where engine load is higher. As Steve mentioned, knock or detonation becomes a problem at higher boost for several reasons, and that is the big engine killer. My MAF/ECM combination can only read to 170 grams per second of air flow and the turbo engine flows quite a bit more than that. Your ECM may be have fuel and timing maps for the full range of 255 gr/sec, which would be a big help. I had extensive communication with Bob Bailey of Bailey Engineering about their MAF Translator+ and his feeling was the ECM limit I have would make that useless to me. I have no experience with the mini AFC. I also have an alcohol injection system which is in the process of being tuned but so far the results are mixed. This combination has approx. 15k miles on it and is my daily driver during the summer.

For the winter I am attempting to modify the air flow pattern inside the intake manifold, which is lousy even for an n/a engine and gets worse with boost. My assumption being some cylinders are lean, probably the knock sensitive ones, and others rich. The other project will be to see about relocating the MAF to the compressor inlet and possibly making an air/water intercooler. Regarding the strength of the engine itself. A guy on the GN forum experimented many years ago with the first 3800 engine blocks to see if they would be a viable replacement for the older turbo blocks. He had the power up to around 500 hp before it blew the crank out the bottom. I would think 350, maybe 400 hp would be relatively safe if detonation is kept under control. While I am not as familiar with the newer engines, mine has a rolled fillet crank and I assume the newer ones do also. For reasonable longevity, my combination is rarely given full power from a stop, the stock transaxle has 124k miles on it and is holding up so far. This is an old mechanically controlled transaxle and the turbo boosts so quickly it will go from about 12" of cruise manifold vacuum to 8 psi of boost during the downshift @ 70 mph.

thanks, for all the info, i hope you stay here and visit often to help

and welcome BTW