Need Help Developing a Buick 4.1L Single or Twin Turbo '86 Vette

[turbov6vette]

Just like the title says, I plan on developing a Buick powered 4.1L single or twin turbo '86 'Vette and need help in doing so. I know it's going to take some work, time and money to do it, but, if done right, it could be one of the ultimate Buick turbo hybrids out there.

Obviously, I already have the '86 Vette and I have a line on an 1983 Buick Regal with a 4.1L carb'd engine and a 3 speed automatic column shifted transmission. I don't know what the casting number is, but I've asked the owner to check it out and get back with me.

I plan on bolting the 4.1L engine up to the Vette's 700R4 automatic transmission. I believe I bookmarked a site that sells an adapter plate for this, but perhaps someone on the forum has some insight on this combo.

So, that's the grand plan. First of all, I'd like to seek a sanity check from you Hardcore Core Big Bore TB'ers out there. Please feel free to chime in now and tell me that I'm crazy, and that a single or twin turbo 4.1L Buick-powered Vette can't be done for under $5000, not including the donor car. Someone, please talk me out of this before I start obsessing that it can (and will) be done.

If it can be done on this budget, then I'm all ears. Please tell me how you would build this hybrid with the Vette I have, the 4.1L Regal I can get and the additional parts and work I need to make it happen.

Without further ado, I'll turn the floor over to the TB'ers in the know...

 

[charlief1]

O-K. First, dump the 700r4 for a 2004r. Better ratios and can be buildt just as hard. As far as twinns you will have a great deal of work. Look at chevy's GTP program. they ran a twin turbo prototype 4.3 that was extreamly modified in the 80's. Are you wanting to do drag, SCCA, or what? give me an idea of what you want to play with. My last engine cost me just about what you're wanting to spend for just the machine work.

 

[turbov6vette]

Thanks for kicking in to the thread. I had been looking at doing a turbo or supercharger set-up on the 5.7L TPI engine, but there's not a lot options out there. The question I've been asking myself is "do I really want to invest in old L98 350 or swap in something - like a TB engine - and create a 600+ hp hybrid Vette Buick turbo V6 beast?"

I'm thinking beast with a Big Bore 4.1L built with SCCA / autoX'ing in mind along with the occassional Saturday night drag and smoking all challengers that I might meet at the light. Something that's going attract attention at the local cruise nights, too.

A single larger-sized turbo set up would be perfect, actually. Instead of jumping right into an extensive engine rebuild and mods, what can I do near term to start building a single turbo engine using the stock 4.1L from an '83 Regal? Heads, intake, turbo, intercooler, ECM, etc. and from what donor vehicles?

 

[charlief1]

welcome to the bastards. Were' just a little different. If you're really interested in something unusual then you're in the right place. Give me a better idea of what you're watting to do and maybe I can help.
charlief1@hotmail.com

 

[turbov6vette]

charlief1,

Bastards are some of my favorite people, so I guess I'll fit right in here. :wink:

Basically, I want to get rid of the old 5.7L L98 TPI engine in my '86 Vette and replace it with a turbo-modified 4.1L engine out of a '83 carb'd N/A Regal. The questions I have are:
- How to go about modifying a 4.1L N/A engine and turn it into a turbocharged, intercooled powerplant that I can slap into my C4 Vette?
- Can a basic turbo mod be done using a stock 4.1L engine without having to dive deep into rebuilding the engine? If not, then what engine mods would need to be done?
- Can that 4.1L motor be adapted to bold up to the 700R4 automatic that I already have in the Vette?
- How hard would it be mod in a TB 200R4 to the Vette, if I decided it would be advantageous to go that route vs. keeping the 700R4 in the car.
- Who would I need to talk to about doing a C4 to TB hybrid wiring harness for the swap?
- What type of ECMs or aftermarket engine management systems are available to use for this type of project?
- Can I use the same Dana rearend that's in the Vette, or would I need to upgrade that, too?
- Would this be a total nightmare of a project, or is it feasible?

 

[Kovmat]

Just saw your post. I don't want to waste your time since I am very much at the beginning of the learning curve on my project but it may make you feel better that you are not the only one taking on such a project. I have a 52 Willys pickup that has a 4.1 NA in it now. I just picked up an 86 GN motor with everything but the turbo and intercooler on it. I plan to transfer that setup over to the 4.1. As far as I have been able to determine everything should bolt up to the 4.1 with the exception of the oil return from the Turbo. You will need to drill and tap a hole in your block for that.

I remember reading an article a couple months ago about the procedure for doing this, I forgot to bookmark it and I can't find it again. I will keep looking and will link it here when I come across it.

 

[turbov6vette]

Great info, Kovmat - thanks. I think I came across an article like that myself not too long ago. Cool. Not being very familiar with the engine yet, I wonder if the oil return hole can be drilled out in the block without having to disassemble?

 

[Kovmat]

The oil return hole is located in the front of the engine toward the passenger side about 2" below the manifold. I was looking at my 4.1, there are 2 ribs in that area, It looks like the hole will fit between those ribs. I am not sure how much of the engine would need to come apart to do that. I am hoping just the intake and water pump. I am sure some of the guys on this board have done this they can tell you much better than I can.

I have also read that you can also put the oil return in your oil pan. You probably would need to weld in a fitting though. My plan is to put it in the block.

 

[charlief1]

Don't forget that there are at least 2 other boards on turbo buicks. gnttype.org and turbobuicks.com . There may be some other info that you can dig up there. I'm in the process of redoing an 83 t-type with a stroked 4.1 and a carb. I may end up going to SFI but for now all I'm trying to do is get the d_mn thing in a drivable condition.

 

[Kovmat]

I just remembered a company that may be able to help you hooking up to your 700R4. Advance Adapters.Com. They do make adapers for the Buick v6 to various transmissions. Give them a call they may be able to help you.

 

[CTX-SLPR]

4.1L Comentary, for a durable 4.1 that will take the abuse of truning it you should invest in a set of custom forged pistons as off the shelf forgings don't exist. The stock lower rotating assembly should be good but I'd add the front 3 billet caps for insurance since like me you are not likely to have enough chassis clearance for a girdle. The top end should work fine after you swap the intakes out. For the oil drain you can just run it into a bung on the pan or into the fuel pump blockoff plate if you don't want to put a hole in your block. Definately go through and full rebuild the engine if you are going to invest in the trouble of putting it in so you don't have to take it out.
Twins, not a good idea unless you want to custom fab not only the headers and exhauste pipe but also the front accessory drive or spend the money on a Champion eliminator setup. The transmission issue is a bit of a sticky one, if you have a well built TH700-R4 then I'd get an adapter plate and just run that since messing with a tranny in a C4 'Vette isn't fun with the semi torquetube enclosure on the driveshaft. If you don't have one.... well you will spend about equal money on building them both up to a certain point but the TH200-4R will likely be an overall more durable unit. For your application the overdrive ratio isn't likely to be as important as any overdrive will work for the street, the TH200-4R will however have a better ratio spacing for an Auto-X application but will require a custom driveshaft (not too big of a deal), trans crossmember (if you don't have the fab skills this could be pricey), and probably shift linkage.
Other problems faced by all the rest of us with hybrids in vehicles that never came with a Buick V6 is motor mounts, oil pump clearance, oil pan sump fitment, and the wider valvle covers and headers of the Turbo6 over an SBC. For me the problems are so bad that I am modifying a 1 year only oil pan to fit around the steering and engine crossmember, have eliminated the spur gear pump, gone with a custom external feed gerotor oil pump to clear the crossmember, and I've not even started to check clearances for the headers. The wiring harness issue could probably be handled by Casper's but you probably don't need to go that far. Your '86 L98 will still have a roughly independent engine and chassis harness so your task will be taking the existing chassis leads for things like the engine sensors to the dash and seperating them out so you can keep the guages working and splicing the LC2 harness leads for things like fuel pumps, cooling fans, and probably the AC idle advance into the existing chassis harness and just fish the whole LC2 ECM connector into the spot for the L98 ECM after pulling the L98 harness out.
Sounds like you have a really awesome project in the making, my advice is to make a plan, stick to it and piece it together as time and money allows. Be prepared for lots of complications and fabrication and ask for help. Last bit is don't pass up any parts as beneath your car, even the crappiest Honda and ricer boy stuff might hold a niche solution for a problem you are facing.

Goodluck and look forward to seeing another member of the 4.1L Turbo6 hybrid club,

 

[turbov6vette]

Good info, guys. I checked out the Advance Adapters site - looks like the part might only be around $120. I'll have to check it out further.

Came across a good thread on the site here at http://www.turbobuick.com/forums/engine-tech/231471-86-87-heads-85-block.html. Check out the post by WickedV6 relative to the 4.1 block.

Here's a few other good hybrid conversion links I pulled out of my Favorites bookmark folder:
- Really good one: 4.1 Recipe
- http://www.turbobuick.com/forums/general-turbo-buick-tech/195784-need-info-4-1-engine.html
- http://www.turbobuick.com/forums/general-turbo-buick-tech/169522-4-1-questions.html
- - Turbo Charged Buick V6 - Feature - GM High-Tech Performance
- 3.8L Buick V6 Engine Swap - Toyota at Off-Road.com
- BEFORE BLACK - Turbo Conversion
- Building the SFI/Turbo V-6 Vega

We've got a good thread going here - let's keep that information flowing!

 

[turbov6vette]

CTX-SLPR,

All I can say is WOW - excellent info! I must have been working on my last post when you posted yours. I noticed you had posted on a few of the links I listed. We're pleased to have your input here.

 

[turbov6vette]

Here's another excellent 4.1L article: TurboBuicks.com - Build a Budget 4.1 Motor!

 

[Kovmat]

turbov6vette, Thanks for all the links, you found the one I was thinking of. I need to start bookmakring these.

 

[WIKEDV6]

Well, as you know, there is more than one way to skin a cat. That being said first of all what you need to do is to set a realistic goal on what you want to run? What hp level are you looking for? This is going to determine what area you need to strengthen in the motor. If you are looking to just get the car running pushing 5-10 psi boost you maybe able to get away with the NA pistons that are in there assuming no knock and good fuel. The NA motors were also 8 to 1 compression ratio. We ran a NA motor with 12 psi boost for about 30K before it spun a bearing. The cheapest way to get a better set of pistons would be to get some hypereutectic pistons for around $200. Most people are scared of them but they are better than NA pistons. The proper way to do it is to get a set of forged pistons like Diamonds for around $600 bucks.
The 4.1 motor from the factory come with the same crank as the turbo motors, they both have rolled fillets, rods and mains. Once again if you are not going to push this motor yet run pretty good then you can keep the crank and rods. Change the pistons to hyper or forged pistons along with good ARP hardware.
If you want build this motor to get every ounce of power out of it then build the motor with 4340 crank and a Girdle or two middle steel caps along with forged pistons and all ARP hardware. Better yet, Full Throttle Speed has the stroker kit for around 1500 bucks to make that 4.1 into a 274 cube stroker motor.
You can also get a good set of ported iron heads with good valve springs and ported intake. I would suggest a good roller cam setup if not you can take your chances with flat tappet cams and see how long they will last. Also a good turbo, like a 70 or 6776 or something. With the Vette you would need a custom front mount IC.
You can run the 700r4 behind the motor with the adopter. There is a guy on Turbobuicks.com named John Lindsay ran a 700 behind his Buick powered 240 Z and he was running 10.1's with it. I think he just sold his car.
There was another guy on Turbobuicks.com named Rouge Vette with a Buick stage II motor that has gone low nines. His web page is not working now but it's bad a$$ car, I think it was an 86 Vette.
You can order you custom engine harness from Casper’s Electronics at 847-247-0484, they will get any type of custom harness made for you for around $600-700 John is very knowledgeable and great to deal with.

HTH

Prasad

 

[WIKEDV6]

Drill & tap size

Just incase if you guys are looking for the drill and tap size

The drill bit is 23/32 and the tap is 1/2 - 14 npt

HTH
Prasad

 

[turbov6vette]

Thank to all for your input. After a lot of research and consideration, I've decided to do the turbo build-up using my existing L98 TPI 5.7L V8 engine using a Megasquirt II v3.0 and Ford EDIS 8 combo distributorless set-up. The stock TPI is already in the car, it works (or should work once I install the combo) and it will be a much easier project to complete vs. a 4.1L N/A turbo conversion. I appreciate all your help, though.

Someday, I'll buy a turbo Buick and have some fun.