Guest TurboSedan Posted June 10, 2005 Report Share Posted June 10, 2005 i am totally new to the Buick 3800 engine, and have a few questions about turbocharging the L27. basically i'd like to add 8-10psi with a FMIC. yes, this would be for my '94 Bonneville SSE, but we all know that the L27 is a W-body engine too so i thought i might as well post it here. some questions.... - what is the compression ratio of the L27? i've heard some people say it's 9.0:1 and others say it's 8.5:1 - what would be the best way to block off the rear exhaust manifold dump? simply block it off or? would it be possible to use exhaust manifolds from a RWD 3.8L engine on an L27? - how much boost would the stock MAF sensor handle? how would i add fuel and timing? would it be better to go with an aftermarket speed density standalone system? - how would the stock L27 cam react to boost? too much overlap? is the L67 camshaft any different? - would i be better off starting with a Series II L36? any ideas, suggestions, discussion much appreciated. please no replies like "just drop an L67 in there" i might just end up doing that, but i'd like to know what's going to be involved in turbocharging a 3800 first. Quote Link to comment Share on other sites More sharing options...
94CutlassSLCoupe Posted June 10, 2005 Report Share Posted June 10, 2005 I don't know much about the other stuff, but the Series II engine has a much stronger bottom end in it...than the L27 Quote Link to comment Share on other sites More sharing options...
topless94style Posted June 10, 2005 Report Share Posted June 10, 2005 I think that engine also has a higher C/R than the S/C engines, so ill take a swag and assume its higher than 8.5:1. You will probably want to stick with the MAF sensor, itll be easier to tune that way. Get some GTP injectors, a FMU, upgraded fuel pump and you should be able to control the fuel pretty good that way. Using the bigger injectors may cause problems during idle, so you dont want to go too big. The other option would be to go with a nice big set of injectors, and tune the computer accordingly to adjust for the larger flow injectors. More than likely on that engine you could run 30-34lb injectors and i imagine it should run good under normal driving, and with an FMU increasing the fuel pressure with boost should help out when you go WOT. I wouldnt reccomend blocking off the dump, i cant imagine that being good for flow. Then again, im sure the stock manifolds suck anyway. I would look up and see if the RWD manifolds would fit. Dont know much about the camshafts. Expect to spend a good amount of money, probably the same amount spent on an L67 would get you farther, but whats the fun in doing it the easy way? Quote Link to comment Share on other sites More sharing options...
Intlcutlass Posted June 10, 2005 Report Share Posted June 10, 2005 Is this because of your 3.1 Turbo timing chain thing... Are you going to replace that engine with a L36/L67??? Oh and the the differences.... Here is a quote from the Thrasher site: "No. You cannot simply bolt on an Eaton M90 blower onto a L36 and make it work. Most importantly, the heads are different. The fuel injectors on a L67 are placed into the heads, while on a L36, they go into the intake manifold. While the supercharged L67 heads and the L36 normally aspirated heads were identical in 97-98, the injector bosses are not machined out to accept the injectors. In '99 and newer, the L36 heads went to a different casting, and these injector bosses no longer exist Other differences between the L67 and L36 engine are the pistons and rods. The pistons are stronger on the L67 (but obviously not strong enough for our 370 HP engine! Click here to check out the damage a piston can do when it shatters during a run!), and height is different, making the L36 have a 9.5:1 compression ratio vs. 8.5:1 on the L67. This means even if you could get the lighter rods and pistons to live under boost, you wouldn't be able to run nearly as much. The cam, crank and block are the same, but the cam gear is different to allow the cam to be installed advanced in the L67." Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted June 10, 2005 Report Share Posted June 10, 2005 The Series I L67 and L27 actually had the same compression ratio. Try and get ahold of Dr. Jay on BonnevilleClub.com. He can probably tell you everything you want to know. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted June 10, 2005 Report Share Posted June 10, 2005 The Series I L67 and L27 actually had the same compression ratio. Try and get ahold of Dr. Jay on BonnevilleClub.com. He can probably tell you everything you want to know. Has he actually confirmed that or is it just what he believes? I know Shawn has 9.0:1 listed for the L27 on the main site here. Either way, if it's 8.5:1(or whatever the series I L67 is) or 9.0:1, it's still decent for boost. As far as manifolds go, I would fabricate some simple manifolds similar to what this guy with a Fiero used for his turbocharged L67. http://www.fierox.com/turboproject.htm ^That car made 468whp and 482 ft-lbs to the wheels non-intercooled, so I think some similar styled(properly sized) manifolds would be more than adequate for your application. For the camshaft question, I would ask the guy that Shaun mentioned above, I think he's one of the guys that got the aftermarket cams available for the Series I 3800's(???). If so, he should at least know all the stock cam specs(I haven't ever found anything on these cams other than valve lift from what I can remember). Keep this updated! I've thought about using a Series I 3800 for a turbo project before(probably wouldn't cost much considering I can find a suitable motor in just about any of the junkyards in my area with not that many miles on them). Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted June 10, 2005 Report Share Posted June 10, 2005 Is this because of your 3.1 Turbo timing chain thing... Are you going to replace that engine with a L36/L67??? Oh and the the differences.... Here is a quote from the Thrasher site: That Thrasher info is kinda old(most likely..haven't checked out that place in a while) and should be taken with a grain of salt. Check out some of the turbocharged L36's on ClubGP and elsewhere(in other L36 powered cars).....they are making quite a bit of power safely on stock and nearly stock motors. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted June 10, 2005 Report Share Posted June 10, 2005 Yeah thrasher was the place to go for L67 mods about 3 years ago, then ZZP and Intense were getting known and thrasher was kinda left behind. Series I L27 & L67's both have 8.5:1 compression. I'm also fairly sure they have the same cams as well. You should easily be able to run the kinda boost you want to with a FMIC with a decent turbo. If you have any welding skills I would suggest building a setup like the TGP's with the turbo in the crossover and either fab up your own rear manifold or block off the downpipe exit, although that wouldn't be too good for flow so you might have to figure out a way to modify it to remove that. Then you'll just have to worry about fueling issues and all that once you get it physically put together. The engine itself should be strong enough to take that mild amount of boost, they run to over 300,000 miles N/A with no bottom end failures, so I can't imagine them not being able to stand a little boost for at least 2/3 that mileage. Shawn Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted June 11, 2005 Report Share Posted June 11, 2005 Is this because of your 3.1 Turbo timing chain thing... Are you going to replace that engine with a L36/L67??? nope, the Cutlass should be running and driving within a month easy. i've already replaced the timing chain and had the 2 bent valves replaced with valve job. all it needs is about $150 in parts (gaskets, head bolts, and some fluids) then i need to get wrechin on it (easy). the turbo 3800 would be for my SSE. it is parked now and i'm driving the GTS. it just doesn't have nearly enough power as it is, and i don't think i'll ever be happy with it unless i add boost. i'm figuring the hardest part would be the rear manifold and crossover issue, which i would have to get made for me (i can't weld or fabricate that stuff). i was going to try stopping by the same shop in Ft.Collins, CO that timg used to make up his turbo LQ1 crossover pipe. do you guys think an FMU and L67 injectors would add enough fuel for 10psi? what about timing? i think this 108,000 mile L27 could handle 10psi no problem; it runs great, gets good gas mileage, and the oil stays clean throughout the 3000 miles between changes. it's just slow :? Matt, thanks for the link! thanks everyone for the info! i probably won't be starting this project 'soon', as i have to do some research and planning, not to mention getting the Cutlass on the road first. Quote Link to comment Share on other sites More sharing options...
99RegalGS Posted June 11, 2005 Report Share Posted June 11, 2005 Here is a quote from the Thrasher site: "No. You cannot simply bolt on an Eaton M90 blower onto a L36 and make it work. Most importantly, the heads are different. The fuel injectors on a L67 are placed into the heads, while on a L36, they go into the intake manifold. While the supercharged L67 heads and the L36 normally aspirated heads were identical in 97-98, the injector bosses are not machined out to accept the injectors. In '99 and newer, the L36 heads went to a different casting, and these injector bosses no longer exist Other differences between the L67 and L36 engine are the pistons and rods. The pistons are stronger on the L67 (but obviously not strong enough for our 370 HP engine! Click here to check out the damage a piston can do when it shatters during a run!), and height is different, making the L36 have a 9.5:1 compression ratio vs. 8.5:1 on the L67. This means even if you could get the lighter rods and pistons to live under boost, you wouldn't be able to run nearly as much. The cam, crank and block are the same, but the cam gear is different to allow the cam to be installed advanced in the L67." That applied ONLY to the L36 not the L27. Personally I don't think the L27 will have any problem holding 10psi either. The 36lb per hour L67 injectors can flow enough fuel for 10psi. so I wouldn't worry about that. I'd be worried about the fuel pump wayyyy before the injectors. I'm not sure how much air the MAF on the L27 can handle up to. I would assume that it would be fine for 10psi. and for the ECM why not just get a reprogrammed EEPROM? Check out http://www.gmtuners.com/ The owner of the site has a turbocharged L36 with an OBD1 compuer running it. (not sure if it's the same fiero that Matt had mentioned) IIRC he charges $40 to reprogram the EEPROM. Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted June 11, 2005 Report Share Posted June 11, 2005 Personally I don't think the L27 will have any problem holding 10psi either. The 36lb per hour L67 injectors can flow enough fuel for 10psi. so I wouldn't worry about that. I'd be worried about the fuel pump wayyyy before the injectors. definately getting a new fuel pump. i'm hoping i can get a Walbro 255 just as i've done on my GTS. I'm not sure how much air the MAF on the L27 can handle up to. I would assume that it would be fine for 10psi. and for the ECM why not just get a reprogrammed EEPROM? Check out http://www.gmtuners.com/ The owner of the site has a turbocharged L36 with an OBD1 compuer running it. (not sure if it's the same fiero that Matt had mentioned) IIRC he charges $40 to reprogram the EEPROM. thanks for the link! that's definately good to hear i knew it was OBD-1 (well...mine is actually OBD-1.5 i think) with a memcal, but i wasn't aware there was anyone out there burning custom EEPROMS (not to mention reprogramming them for $40 :shock: ). i've been wanting to get into EEPROM chip burning/editing with the TGP/5-speed chip i have in my Cutlass ECM....it would be great if i could do the same with the SSE. i really don't want to go with a standalone or piggy back system. Quote Link to comment Share on other sites More sharing options...
topless94style Posted June 11, 2005 Report Share Posted June 11, 2005 After doing my own crossover, I would definitly reccomend having it professionally done. Mine is horrible, but it will work. L67 injectors, maybe a 6:1 FMU, the Walbro pump should be a just fine fuel system, highly reccomend getting the computer tuned to suit it though. With 8.5:1 compression, you could run 10psi no problem. Quote Link to comment Share on other sites More sharing options...
ZeroDCX Posted June 20, 2005 Report Share Posted June 20, 2005 So what turbo size/trim would you guys recommend for the L27? This forum interests me as I want to also add a little bit of power to my L27 Regal. Quote Link to comment Share on other sites More sharing options...
Curlybandit Posted June 20, 2005 Report Share Posted June 20, 2005 Being an L27 owner myself, I'd love to see this happen!! Check out http://www.seriesoneperformance.com/ for aftermarket performance parts for the Series I. Page 2 of the "Series One Rides" link shows a turbocharged 3.8L from a '90 Reatta. Quote Link to comment Share on other sites More sharing options...
ZeroDCX Posted June 21, 2005 Report Share Posted June 21, 2005 Wow! :shock: ... that's pretty neat. Wonder if he'll give some specifics on his set-up. Looks very interesting, might wanna try it myself. The L27 lags behind top end ... Keep an eye out though. Thanks for the link Curlybandit!!!! Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted June 21, 2005 Report Share Posted June 21, 2005 I'm not sure how much air the MAF on the L27 can handle up to. I would assume that it would be fine for 10psi. For what it's worth, I read on the Bonneville board that the L27 & L67(series I) MAF sensors are the same. Quote Link to comment Share on other sites More sharing options...
Curlybandit Posted June 21, 2005 Report Share Posted June 21, 2005 Wow! :shock: ... that's pretty neat. Wonder if he'll give some specifics on his set-up. Looks very interesting, might wanna try it myself. The L27 lags behind top end ... Keep an eye out though. Thanks for the link Curlybandit!!!! No problem Quote Link to comment Share on other sites More sharing options...
ZeroDCX Posted June 22, 2005 Report Share Posted June 22, 2005 So what size turbo/trim do you guys think that he's running? How much boost can a stock L27 handle w/o problems? This really interests me, I wanna know more ... L27 power baby. Any info's greatly appreciated. Quote Link to comment Share on other sites More sharing options...
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