advice wanted

[80sunbirdcoupe]

Hello everyone!! I haven't posted much since I've been a little busy since I registered but since spring is starting soon its time to start thinking about getting summer projects going. Since everyone on this board has had a lot more experience with the carbed 3.8 than I have I figured I would ask here first before I buy alot of unnecessary stuff. As it stands now I have a 1979 Regal Turbocoupe thats in rough condition (to put it nicely), but the engine is complete and turns over and has reasonable miles (I think 93,000 miles) I guess it ran when it was parked in 1990 lol I would like to put the V-6 in a 1980 Sunbird I have that I repainted and fixed up. The Sunbird currently is a 2.5 Iron Duke with a 3 speed hydramatic (I think its a turbo 200, I haven't looked at it too much though) with no air conditioning. I would like to make it just a pretty fun car for driving (nothing too crazy, my goal is around 225 to 275 h.p. at the crank) that I can autocross (hence the v-6 as opposed to a small block chevy)and maybe make a few passes at the strip once and a while. Anyways what I would like is to:

Keep the torque arm suspension (so I have to keep a stock h-body transmission)

Convert the Sunbird to a manual (Saginaw 4-speed) I'm a little flexible on this, but I would really prefer a manual

Keep a stock hood (I'm real flexible on this, but the less body work the better since I just painted the car last year)


Should I keep the engine a turbo or should I find a nice aftermarket 4 bbl intake and convert it to NA? I'm going to rebuild the engine so I have alot of options that way. I've heard (from fc227 and others) to not put a manual behind the turbo because it will lose boost between shifts, but will that just hurt my 1/4 mile times or will the thing be almost undriveable? I haven't heard of anyone who has actually done it. Consistent 1/4 mile times are a pretty low priority compared to having the car be fun to drive and being decent at autoX. Ideally I would like to keep the car a turbo (even with putting a cowl induction scoop on the car) and a 4-speed, but I thought I would ask the group what their thoughts are. Thanks!

 

[turbofish38]

Well I'm kind of an expert on some of this stuff. Here are my thoughts. I have a Cosworth Vega that I also auto-X so I would keep the stock torque arm and suspension. The rear is good for at least 250 HP. Stay with the auto, it will be easier to drive and you dont have to worry about boost spikes and turbo lag between shifts. The stock Saginaw 4-speed has a 3.11 or 3.5 low 1st gear so you would have to have a 2.41 ratio or higher(lower number) to get any traction. The turbo would be a bolt in with some mounts from a V-6 Skyhawk but you would have to fabricate a downpipe. I also think the plenum and carb sit to high so you would have to cut a hole for them. I hope you are going to auto-X just for the fun because your turbocharged Sunbird would most likely be in the Modified class with all the pure race creations and stock bodied and stock suspension cars usually dont do well in that class. Maybe a NA would be more competive? I'm not trying to burst your bubble or anything but one of the reasons(other than money) that I dont auto-X my CV or GN on a competitive level anymore is because it is really tough keeping up with all the newer cars out there. Good Luck on you future project.

 

[80sunbirdcoupe]

Hey thanks turbofish for the reply! I'm pretty much planning on doing it for fun so I don't really plan on bringing home any trophies, but it probably wouldn't be too much fun to be consistently last lol. It makes sense to stay with the automatic with the turbo, but would there be any benefit to go with the 4 speed with a NA motor? Would I still be in the Modified class if I went with a 4 bbl set up since the cars never came that way? I would like to have a manual, though the car would be pretty fun either way, but as it is when I drive an automatic car I start looking for the "phantom clutch pedal" lol I just won the mounts on ebay from a monza that had a 3.8 Buick so I'm set there, plus I have DOBI springs (1" drop) and front sway bar (and A-arms for sway bar). I still need to get the rear sway bar and a posi for the rear end, and new bushings (probably polygraphite). None of this is on the car yet. I'm on the fence because I'm at the point that if:

I go with the turbo with automatic I need to:
Modify the hood
Get the proper bellhousing for the trans.
Beef up the trans for more power or find a th300 from a monza
Get a better torque converter
Rebuild the Turbo (on top of rebuilding the engine)

I go with the NA 3.8 with a manual I need to:
Get a clutch,transmission, torque arm, trans crossmember, maybe driveshaft? (I have the pedal set and shifter already)
Get an intake and carb
Get or build headers (or at least manifolds lol)
Get a Manual Flywheel

Of course this is with on top of everything else needed for a swap (routing exhaust, throttle cable etc...) I'm pretty lucky because I have a pretty stripped down car, so the only engine mounted accessory I have is power steering. I have manual brakes and no A/C. If I go with a NA motor I think I'll get the heads done and get a better than stock cam for a little more power. On a side note, since you've raced H-bodies before, is 215/60R13 tires a good size for autocross? This is what I have on right now because you could get slicks in the same size Thanks for the help!

 

[b4black]

Do you have "Building the V6 Vega" by John Thawley?

 

[fuzzyGN]

I have done the Buick V6 thing into a Vega so I have kind of "been there done that." I also happen to have 2 parts cars right now both of which are V6 cars with A/C and one is auto and the other is 4spd. Anyway, I had a complete 84 turbo drivetrain that I was going to put in the Vega and didn't. I can be done but not unless you have some skills fabing stuff. For the 84 the exhaust manifolds wouldn't fit in stock form, a DP would have to be built, the wiring harness ..... I built a stout 4.1L instead. It is still plenty peppy and it is a fairly mild compression engine. I do have a 5spd behind it too which keeps the grin factor quite high. If I were to do it again I would probably stick with the N/A and a 4speed. Just add a cam, headers, a 4bbl manifold, a 600 Holley, and port the heads some. Even on a 3.8L that will get you somewhere around 225 to 240HP. That may not sound like much but what does the car weigh? Not much. I also converted mine to 5 lug using S-10 axles in back and Regal spindles in front. Super fun cars and not too expensive to make quick. I have a ton of parts if you are looking for something. Let me know.

 

[BiGBoY]

That kind of power, is it with the actual 8.0:1 compression ratio ??

 

[fuzzyGN]

Yes stock compression, but most 3.8's had a little over 8 to 1. The power comes from the heads really and a cam to match the desired power band. Fortuantely, the Buick has no problem producing torque so a bigger than normally expected cam can be used and still be very quick on the street. Of course a bigger cam (to a point) will make bigger peak HP. It really depends on ones goals and then matching the engine combo to the goals. My next milestone is to build a N/A 4.1L that can produce 300 HP without the use of nitrous. I think it can be done but it won't be easy.

 

[unboostedV6]

My next milestone is to build a N/A 4.1L that can produce 300 HP without the use of nitrous. I think it can be done but it won't be easy.

It can, has been, and wasn't...GB

 

[80sunbirdcoupe]

Thanks for all the advice so far, I definitely have to get that book!

Does anyone know if any companies make headers for this swap?

 

[fuzzyGN]

If you are going with the N/A version then yes, there are headers available. Unfortunately, I don't know of a single company that still makes them new. I have several sets but they all came from ebay. If you do find a set, make sure they are for an H-body because nothing else will fit. Another "been there, tried that." I know of a few manfac. including Hooker, Headman, and Dobi. The Hookers are by far the nicest, biggest, and bordering on silly unless you are going all out. Not only that hard to find' you will pay big bucks, and a total biatch to install. The Dobi's are not as well made but they are a full length header with realistic routing and tube sizing. Almost impossible to find used though. Headmans are nice, easy to install, and are a 3/4 length which will boost the high end HP without really hurting the bottom end much. The only drawback is a little extra work plumbing the exhaust due to the 3/4 collector length.