My 90 Firebird, 87 LC2 swap...

[cabech984]

After about 3 months of deciding on a LS1 or Small Block swap I stumbled on a 3.8L Turbo last Friday and am picking it up for $800 tomorrow. So much for decision making. Im coming from thirdgen.org & ls1tech.com & hope to get alot of knowledge from this site over the coming months (or years). Anyways, for $800 I'm getting:

87 3.8SFI Turbo engine ("109" block)
(engine is complete from tb to oil pan)
Accessory drive components
ECM w/ aftermarket chip(unknown)
Factory Harness
GN Exhaust Manifolds
Factory turbo & intercooler
Kenne Bell Upper intake and throttle body
ARP Connecting rod bolts

Of course the engine needs rebuilt & the owner suggested that a rebuilt turbo or a new one is needed. Engine ran before pulled from a rough T-Type or GN?? owner said the engine ran 11.90 as it sits now.

I am definatly rebuilding the engine as well as possibly upgrading to a bigger turbo as well as a FMIC. I have to use a 1LE heater box or modify my stock one. Im likely using a TH350 transmission. I got a few pics of my car and new engine as well. Hope you all like!! The car is a 1990 3.1 liter. Ive upgraded the rear axle, its a 10 bolt & aluminum Driveshaft from an 01 Trans Am WS6.

 

[cabech984]

Here are a couple of the engine

 

[88ZNX]

sweet!

That is going to be one sweet ride! I did a 88 Iroc Z swap, you can view pics of the swap and get some good info on my webpage if you'd like.
Welcome To My Website click on Alan's 88 ZNX

Good luck with the swap! Let me know if I can help with questions

Alan

 

[cabech984]

Thanks for the link Alan, I hope everything goes well w/ my swap. I love the name "ZNX" I'm 110% sure I'll be asking some questions too!! If I dont use a stud girdle, I wouldnt need the plate steel under the frame mounts right?

This swap is going to take quite a bit longer I think, compared to a V8 swap but it'll be worth it for sure. Just sucks b/c Im in college and saving to do this!!

 

[88ZNX]

Thats right. you dont need steel plates under the mounts without a girdle. We just put a stage II in and didnt need the plates. We went back with stock GN frame mounts. Which lowered the engine, and made more room to install the spark plug wires on the backside of the coil near the firewall. plus its easier to get to the two top tranny bell housing bolts.

 

[cabech984]

Thats right. you dont need steel plates under the mounts without a girdle. We just put a stage II in and didnt need the plates. We went back with stock GN frame mounts. Which lowered the engine, and made more room to install the spark plug wires on the backside of the coil near the firewall. plus its easier to get to the two top tranny bell housing bolts.

Do you know if the 3.8L turbo & non turbo mounts are the same? Any idea on where you placed them on the frame? were they on the V6 mount holes or V8 holes? Thanks for the informative pics from your site!!

 

[88ZNX]

The motor mounts are the same for Turbo or N/A. When I put the engine in the car, I bolted up the tranny to the stock location so the driveshaft would remain factory. and where the engine sat on the frame is where I drilled for new holes.

 

[1QUICK85]

Good to see you made it to the Darkside, these guys will take care of all your needs. I was looking for Alan's pictures the other day to send you, glad to see he chimed in. I hope I get a deal like that on a LC2 someday. Best of luck with the build. :biggrin: -Nick.

 

[cabech984]

The motor mounts are the same for Turbo or N/A. When I put the engine in the car, I bolted up the tranny to the stock location so the driveshaft would remain factory. and where the engine sat on the frame is where I drilled for new holes.

Cool, looks like I'll have to do that as well to keep DS upgrades to a minimum:smile:. Im still unsure on which Tranny to use, Ive heard a little about people switching the 1st gear in them to better suit the 3.8 Turbo. I have a long tailshaft th350 that my bro may be pulling from his firebird but its Chevy BP. I'll have to figure that out too!!

Yeah, I was actually referred by a couple guys on TGO to come check the site out!!

 

[trading t/a]

Cut the bellhousing off and use a jw ultra bell on the 350. it bolts to the tranny using the front pump bolts.....

And you wont have to worry about cracking the stock bellhousing.

HTH!

 

[cabech984]

Well, I picked up the engine today. I still got to get the PCM and Turbo from the seller, I picked the engine up at his speed shop and the turbo/pcm were @ his house. Needless to say, I got a truckload of stuff. Turns out, the intercooler & cooler shroud are nearly new, Its got newer crank & cam sensors, Fuel Pressure regulator, Alot of misc. piping & hoses. Its got all the vaccum lines off in one piece.

I have to replace a connector on the harness, it looks fried. Oh well, it is in great shape, the owner before the guy I got it off of painted the intake manifold, front cover & valve covers black, doesnt look very nice. Oh well, I'll fix it up for sure. It doesnt need rebuilt but I'm gonna hone it & install new rings & bearings anyway. I'll likely upgrade the camshaft too. I got a bunch of other crap too.

I paid $800 for everything in the truck. Here is a pic!

 

[tthorngen]

go with a 2004r, or if you already have the th350 why not use it. always fun to save gas

 

[cabech984]

go with a 2004r, or if you already have the th350 why not use it. always fun to save gas

Yeah, I'm still undecided. I dont have a th350 but a buddy may have a BOP core I could get for cheap and Id build my own!!

 

[91Bird305]

Sweet! Another thirdgen LC2 swap! I have one in my 91 firebird that I ran this summer for a little bit and than converted to roller and threw on a couple extras this winter.
Turbo91Bird's Page

If you're going to replace the cam, go with a roller setup from comp cam. That's what I did. Link to the kit is on my website under the mod list. I went with the 212/212.

 

[88ZNX]

I really like the look of those wheels, i missed a set of SLP Firehawk 17X9 wheels from a 90' Firehawk on ebay, they were still in the plastic and went for 500. About the trans, i cant say what to use. i tend to think more on the extreme street car thinking so i run a TH 400 and 4000 stall. but before i switched i was braking the first engine in on the 700r4 with a bellhousing adapter and i was loving the streetability of it. i was able to knock off a 04 Cobra top end, but cant do that now. You need to decied what your going to do most. cruise or race. I race

 

[trading t/a]

I've owned tta 656 and would like to get back into another turbo third gen, something about the cars. I'm selling my Buick to pay some bills, but would love to pick up a cheap third gen later on.

This is my idea on the drivetrain. A turbo 400(would love lock up, but cost is a big factor) with a 3600 stall converter. Since third gear is a 1:1 I would go with the 9 bolt 2.77 rear or if money permitted a 12 bolt with 3.08's.

There have been many discussions about gears and show almost no gain or loss with the gear change. That being said the 2.77 rear gear would help the top end a lot maintain decent gas mileage for street driving. Using mickey thompson dr's since they are pretty small would keep the rpm's from dropping to low a 27" tire would drop the rpms lower. Here are some rpm numbers based on mph with the two gearesets.

@75mph the rpms would be roughly 2700= 336 x 2.77 x 75 / 26
@130mph the rpms would still only be roughly 4700

The 2.77 gear may be a little low for all out performance.

With the 3.08 gear:

@75mph the rpms would be roughly 3000 probably not good for cruising.
@130mph the rpms would be around 5200 decent for track performance.


A really good choice would be to swap to a smaller 1+2 gearset in the tranny and use the 2.77 that'll give you very good launch/accelerating characteristics, but still keep the rpms low on the top end and cruising.

Keep in mmind these are rough numbers, since the dr's are smaller than 26" and converter slippage would send these numbers higher and lower respectively...

That's enough blabbering, hope this helps.....

 

[TTA850]

This is my idea on the drivetrain. A turbo 400(would love lock up, but cost is a big factor) with a 3600 stall converter. Since third gear is a 1:1 I would go with the 9 bolt 2.77 rear or if money permitted a 12 bolt with 3.08's.

Thats not a bad idea, I originally put my GTA together with a 3.08 geared 12 bolt and went 10.69 @ 125 w/1.47 60ft on 26x11.5x16 ET Streets with those gears. Downside was it wouldnt run with 28" tires and traction wasnt consistant with 26" tires. I bracket race alot and consistancy has been alot better with 3.42's and 28's out back.

My opinion is on a driver that doesnt see much track time 3.08's with 26's works great. On a car like mine that sees alot of track time and competition I'd go with 3.42's and 28's.

Steve

 

[trading t/a]

i know on my old 87 T/A 350 car going from 2.77 to 3.27 helped a ton, but some of the GN guys that went to 3.73's didn't see much. I guess the turbo engine is independent, wonder if a v8 turbo does the same thing.

Did you see any improvement on the T/A with 3.42's or was it to get a better tire in there....


Still got the tta's engine in the garage(needs a cam and cam bearings), have the fmic in basement, 55's and modded ecm in the current car I'm thinking of gonna go back to stock to sell.

I'm interested in maybe picking up an fbody for a swap, need to pay bills first before that happens though.

Might wanna do a camaro instead, had the TTA just might like it better....

 

[cabech984]

Well, Im still uncertain on the tranny. I may end up buying a new th200r4 if I can afford it. The rear axle in my car now is a 3.23,G80, Disc Brake unit from an 01 TA. I dont think Im gonna pull that out since I just threw it in there. I also have the 3" aluminum driveshaft from the same car.

I tore down the engine last night and found out it has an Erson cam in it. I didnt get the grind or part number. It looks almost brand new as did the lifters. Ive never heard of Erson Cams, I found there site yesterday. The number one connecting rod bearing was spun and burnt. Other than that everything looked good visually. I'm gonna probably take the block, crank, & heads to a Machine Shop to get checked out. I'll likely have them do a Valve Job & new guides if needed. I'll have to get the crank polished/turned b/c of the grooves left from the bearing. As fas as the block, I'll have them check it out and hone it and install new cam bearings. I can do the bearings but I hate messing them up!!

 

[Kevin87TurboT]

cabech984,
Another alternative for you concerning your transmission is a TCI adapter plate...part number 230001. If you have a free TH350 transmission with a Chevy bellhousing, then simply buy this plate and you can bolt up the trans to your Buick engine. They're fairly inexpensive, I think around $75.
Kevin