Hello to all! I have just bought my first fiero (86 gt 5spd). I've been around one of these cars for years as my friend has a 3800sc swapped 86gt. He has inspired my thoughts with this build. I have a complete 99 olds gutlass donor car, it was free so I'm runnin with it. I want to build the engine and create a turbo kit of my own. My question is what all needs to be done to the engine to successfully hold up, I'm not looking to pull the wheels off the ground, I just want it to be fun on the street and be reliable. Any good camshafts for these engines? What intake should I use? Stock heads? Things like that I'm looking for. Thank you in advance
It really depends on how much you want to spend on this quest for improved HP. The stock 3800 NA (somewhere around 200 HP IIRC) is a nice improvement over the 2.8 L V6. When you start going beyond that there are many options. I have a 3800 SC Series II tied to a manual transmission that is totally stock except for a 3.4 pulley and larger intake and exhaust tubing. This vehicle dynoed at around 258 HP and 300 ft/lbs of torque at the wheels the one time I tested it. Turboing your engine should yield something near my stock 3800 SC vehicle. I also have a 3800 SC Series III engine with lots of goodies and it goes around 300 HP and 300 ft/lbs of torque at the wheels. I still use the stock heads but have a N* TV, VS cam, manual transmission, Tog headers, 3.4 pulley, large intake/exhaust piping, and an intercooler.
ZZP has a number of performance options for 3800 engines and you can take a look at their web site to get an estimate as to what each mod may potentially add to the engine HP. Tuning the engine can also make a notable difference in the vehicle performance. If you can do your own work, then the price may not be too bad to achieve the desired performance. If you pay someone else to do the work, the price can skyrocket!
I had a race built 3.1 turbo in my Ferrari kit. I loved everything about it from the sound to the reliability. More than enough power. I had no problem keeping up with corvettes of the time (late 90s-early 2000s). When I sold the car, a friend bought and swapped out the engine for a used 2.8, but left the DS 1 turbo on it. Hes still racing in SCCA with the same engine.
I topped my dished pistons (intended for small-chamber aluminum heads) with Fiero heads. Good way to lower compression for turbo.
However, you would get better flow if you kept the later-model heads and intake. I'm not sure what is the prescribed method for reducing compression in this case...
[This message has been edited by pmbrunelle (edited 07-12-2017).]
I topped my dished pistons (intended for small-chamber aluminum heads) with Fiero heads. Good way to lower compression for turbo.
However, you would get better flow if you kept the later-model heads and intake. I'm not sure what is the prescribed method for reducing compression in this case...
most people don't, they just run stock compression, it isn't that radical, only 9.6:1 or so. and with the modern heads, it should be fine, guys have run 11's on cam only short blocks and boost in a 3rd gen camaro.
------------------ "I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."
You can run stock compression and 7-8 psi of boost and will get about 210 bhp. If you want more, you need to open up the wallet considerably. I put $5K into parts and machining on my 3.2.
Be aware that a cam for a turbo engine is not the same as a normal performance grind.
Right! I will look around for a turbo specific camshaft. I would like to mention that there's no real power goal here, just wherever it is at a safe zone. The pistons I might just leave alone. At first I was thinking bore it to a size comparable to a 3.4 but it doesn't sound necessary. That would save money on machine work as well. Thanks for the info! Any other ideas?
Is there a factory weak point in the bottom end when boost is added to the 3.1? Ring land, connecting rod, oil pump upgrade needed? Anything like that.
I would suggest that you open up the engine... if the bores are in good shape, then leave the pistons alone.
However, if the cylinders need boring, then you have to buy new pistons no matter what. In this case, it makes sense to try to buy turbo-optimized pistons.
I would avoid boring much larger than is needed to clean up the cylinder... don't want to make the cylinders too fragile. I think that robustness with a turbo is more important than the power gain from increasing displacement. More displacement isn't fun if the engine is broken as a result.
I got Crower to make me a turbo cam based on their catalog lobes. Customer service before purchase: good. customer service after purchase: lacking in quality. These aren't SBCs, so I'm not sure if it's possible to find an off-the-shelf turbo cam.
It seems like parts for the GM V6 are somewhat hard to find/expensive, so my Fiero's next engine after my in-progress turbo project should be an LS-series V8... since the parts catalogs are full of goodies for them.
I don't know of any issue with the GM V6 bottom end (never mind the early small-journal 2.8s). There was a 3.1 turbo version available, and I don't think it had anything special. I read that it had the same 981 crankshaft common to other members of the family. My engine has the 981 crankshaft in it.
That's great information, thank you! What size turbo would give the right spool speed but not run out of steam on a 4th gear wot pull? I honestly don't know much about the capability of the GM v6, as I have only ever built sbc, sbf and modular ford engines. Forgive me of my newness!
