85 GN VS 86-87 questions

[Scott Long]

I want a GN bad. I seem to be seeing the hot air cars cheaper than the more popular 87 intercooled cars and the 86 intercooled cars. I'm not new to this board but I'm new to tech info on GN's. Yes I know a little about them and can hold a conversation, but I would like to know more before I make my decision on buying an early or late model. I like the 84-85 wheels better (stock for stock, although weld pro-stars w/ 26x10.50/15 E/T Streets would be one of my first mods) and the interiors from 85+ but the 84 is feasible too, just don't like the seats as much as the 85+ and I'd prefer not to get a t-top car.

My question is this: If I got an 85 could I install a front mount IC, route the turbo to flow air into the ic and then into the intake manifold and therefore be able to run more boost w/o alky. I don't know how much boost they run stock does anyone know. I'm thinking 15 psi w/ an intercooler and anything higher I'd use 110 octane or alky.

86 and 87 are similar, but what gave the 87 more hp and torque, was it just tuned different or did it have a different cam or turbo?

What stock turbo does the hot air car use? What about the late model GN's?

Are the hot air and intercooled blocks the same? Therefore if I found a set of exhaust manifolds, turbo, ic, and intake and piping could I install it on an 85 long block with no problems?

Do they all use the same trans? Is it a 200R4, 700R4, or something else?

Was posi an option on earlier grand nationals?

Last but not least, when swapping in an 87 intercooled drivetrain into an 85 is it straitforward or is it very tricky? Wiring harness and computer need to be changed?

Oh yeah almost forgot. I've seen low 14 and high 13 second times posted from stock 87's. What do 86's run average stock, and what do the hot airs run 1/4 mile stock?

 

[Vendor Defendor]

'86-87 are the same except for a little different tuning in the chip, nothing else.

I believe the stock '87 turbo is something like a T304

All used 200-4Rs. 86-87 had BRF Tranmissions and 84-85 had a BQ. Mostly the same except for a little different shift points and a different governer.

G80 was available on all TB's

As far as I know, the swap is straight forward provided you have a donor car and you pretty much just unbolt and bolt on. But, if you are going to go through that much trouble, why not just get a 86-87?

86 GN's will be in the same ball park as 87's and I think 85's are in the 15-16 second ball park.

 

[cool 84]

Yes, you can intercool the hotairs in about a day. It typically drops about a second off the 1/4 times. I went 13.9@101mph with an intercooler, K&N, and 13psi.

The turbo is smaller. I went through 2 stockers when I was going 106mph in the 1/4. Broke the shaft in both. I had the wastegate locked shut and it would only make 19psi. I don't think anyone has gone faster with the stocker. I picked up 4mph with 4psi less boost when I switched to a 49. I believe I also swapped downpipes at the same time.

With basic mods they will drop about a second. My dad's with a chip, filter, 20psi (pumpgas), and adj fpr went 14.0@100mph.

A stock hotair can get away with as much boost as an IC car for a given octane. I was able to run 17psi on 92 octane with the only KR being on the 1-2 shift. My dad's for some reason could run 20psi non intercooled with very little knock.

The intake manifold, downpipe, and passenger header are more restrictive and will have to be upgraded sooner than the 87s. Just a port job on the intake manifold will really wake the hotairs up.

Everything from the 87 setup will bolt to the hotair longblock.

Same heads, crank, and rods. Block is slightly different but still pretty strong. Oil drainback hole will have to be drilled for the 87 setup.

A complete IC swap is straightforward. You have to swap engine wiring harness and computer, install a fuel filter in the fuel line somewhere, and make the powersteering/brake work if the car originally had hydroboost brakes.

 

[turbo2nr]

G-80 is the code on the bottom of trunk lid to ID a limited slip. Don't forget that there are more chips, and tuning tools for the 86-87 ECMs. It will be much harder for a novice to get a hot air car flying. More expensive also. So just spend the money to buy a 86-87 as a first TR.

 

[WIKEDV6]

You can use the 84-85 long block and convert the rest to the 86-87 setup, if you are on a budget, slowly collect the parts you need for the conversion, just look for good deals on this board. The major stuff you need are; 86-87 intake and exhaust manifolds, a 86-87 under the hood engine harness, I am not so sure if you can use the 84-85 ECM with a different chip or not, all the accessories up front like the power steering pump, alternator, all the different pulleys,brackets and misc. You have few choices with brake the unit , you can convert the hydro boost setup to work with the 86-87 power steering pump or just buy the 86-87 power master unit from from Autozone for about $150. or you can go with vacuum booster setup like the regular cars. Turbo and injectors, you will be buying bigger one's any way. I know there are few other things you need to do like; feed for the alternator and things, incorporate a fuel filter somewhere, bla,bla,bla. It can be done, we have done about 6 or 7 conversions. The best thing to do is to buy a 86-87 cheep one with some work needed and fix the body or rebuild the motor or what ever it needs. If not, you can take the route we took. Either way you are going to spend money why not start with the right stuff. It also depends how fast you want to go. I will estimate around 900-1500 in additional to the purchase price of an 84-85. We have those cars running hard into low 11’s in race trim and on pump gas , Alky and T plus, we are able to push 24lbs of boost and no knock.

HTH

Good luck
Prasad

 

[chris1]

87 GN

Scott: I am getting ready to sell my 87 GN, and will probably post it on both boards and maybe on E-Bay; 62K Miles, and the usual upgrades; e-mail me privately or call me @ (201) 573-4110 X3530 if you are interested; I am located in Northern, NJ.......

 

[87buick3825]

save yourself a lot of grief ... get an 86-87

 

[t3intercooled]

86-87

IMHO I'd go with a 86-87. I was in your shoes, when I was looking and after heavy thinking due to the much higher cost, I decided to go with an 87. There are just so many advantages by going with the 86-87 than 85. My 87 has a T60 which is a 60 series turbo. I am running around 22-23 PSI on the trafck and 17-18 on the road. I use 100 octane and a shot of alky when needed. But I agree with the others...save yourself a lot of time, grief, and money and just buy an 86-87. E-mail me if you need any further assistance.

 

[Scott Long]

Ok, well I'm glad you can do work to the hot airs to make them faster but I think I will look for an 86-87. A hot air will run about what my automatic mostly stock SC runs in the quarter mile. While I do like the sinister look of the 85 GN, I need some speed. I am aiming for low 11's when I get around to modifying it. Shouldn't be that hard from what I see a lot of you guys are running.

Basically I'll need slicks, 2600 rpm convertor (locking or non locking I'm not decided), bigger injectors, te60 turbo, big fuel pump hotwired, shift kit in the trans, adjustable wastegate, adjustable fuel pressure regulator, chip, alcohol injection, and remove cat and put on a bigger down tube and better flowing exhaust system. Will that stuff get me to low 11's with say 24 psi and 110 race fuel?

Where can I get a scanmaster and how much do those run? Also is it a good idea to change to 3.73 or 4.10 gears to help get it out of the hole quicker? A transbrake would be nice but is it needed to his low 11's? I know when I run a low 11 I'll want to run 10's but I'd be happy to have a turbo regal that is streetable and able to pull off low 11's on pump gas and alcohol. That'd win me some money on cruise night LOL.

 

[85 ttypewh1]

I went for an 85 for a few reasons. The insurance was alot cheaper because of the hp and the fact that 86-87 get stolen more often, and to buy a 84-85 is considerably cheaper. I have alot of cars so I have to buy what is logical for myself, If you look at the advantages of an 86-87 IE. intercooler, better turbo, faster,nicer wheels, then take in account what you will probably do to the car IE. intercoller, turbo, wheels, I dont see the point in paying for those parts twice. If you are mechanically inclined you can do an i/c swap yourself, I am in the process of finishing up my front mount I/c right now and the best part is it looks stock mounted in between the ac cond. and rad. has the 2.5 " openings on each side of the rad and without the tubing i have about 50 bucks in it including the I/c. I had to fab up a few brackets but nothing too hard and i only had to remove a 1"-3" sliver out of the core support for the i/c inlet. Sorry to be soo long winded but i just want people to know that because the stock 84-85 are slower you can make them just as fast as the stock 86-87 for less money than a 86-87 if you do the work yourself and thats half the fun. Now if your are not a mechanic or want to pay someone to do it for you and you just want a fast car and are willing to pay for it then the 86-87 is for you. Just remember if you buy a 86-87 and you ever come to Texas and happen to race a 85 ttype and it holds its own if not beating you just remember my car probably cost a few thousand less.

 

[Scott Long]

Yeah I was thinking if I am gonna buy a bigger turbo and rims and an intercooler anyway I might as well get an 85. Plus I like the 84/85 stock rims better than the chrome 86-87 wheels which I personally think are ugly.

I guess it depends when I decide to buy whats closest to me and what has the best price. I am moving from Michigan to Virginia Beach in a few weeks so maybe this summer I'll find a nice rust free southern GN to bring home.

 

[t3intercooled]

Originally posted by Scott Long
Where can I get a scanmaster and how much do those run?

Yeah scott, You can get them almost anywhere, ramchargers has a good deal on them, and even you can look on ebay they run anywhere from 2 to 3 hundread new, I bought mine used on e-bay for near 110 dollars. So look around, cause they are out there cheaper. That's a good plan to go with the 86-87. But if your not to familiar with the scanmaster, then get someone who is and pay real close attention cause if not, your car may possibly pay with it's life, at least til you can fix it.. Now doing what you want to do should easily drop you into the 11s. Just make sure you get either bigger injectors and/or the 7th injector system. You can find that 7th injector system on O.G.S.'s website, that hidden 7th injector is a wonder .

 

[XLR8]

Originally posted by Scott Long
Also is it a good idea to change to 3.73 or 4.10 gears to help get it out of the hole quicker? A transbrake would be nice but is it needed to his low 11's[/B]

The stock 3.42 rear end ratio is ideal. Most folks running in the 11's - including me - do not use a trans "break". I just leasve off the foot brake at around 12# and hold on. Avg 60' is a low 1.6 with QTPs.

 

[87buick3825]

Maybe you should check the prices of 84-85s .. Ya they are cheaper BUT even after you put thousands of $$$ into them they still wont bring the $$ of an 86-87 an they don't sell easily !! But on the other hand someone has to buy them . Good Luck !!

RD

 

[85 ttypewh1]

Your right! they wont bring as much as an 86-87 because even after spending the thousand or two to make them as fast as a stock 86-87 you will still have less in it than an 86-87. If you mod a 86-87 you wont get your money back out anyways because people who know these cars will want to buy a stock one because chances are it has not been raced as hard.JMO

 

[Zurn]

either way you can't go wrong...

I would go with an 86-87 myself. I have a friend who has spend $3k to get his 85' to run in the mid 13's. He has made a lot of mistakes along the way, since this was his first TR, but still, I just spent $1k and I hope to be in the high 12's this summer. He always talks about selling his so he can get an 86-87 so he can be faster. He tells me, "I wish I knew then what I knew now..." He didn't have a lot of money at the time and found a fast car for under $5k, so he jumped on it without doing research first. I know you are going to hear a lot of peoples personal preferences, so you will have to go with what you think will make you happy. I don't think there is any down side to getting a pre-intercooled car, speed cost money so how fast can you afford to go? I really like the older Buick body, like 78'. I've seen quite a few of the old sports coups go for under $1k and you could buy a totaled 86-87 and swap the drive train out and have a real sleeper car. That would be cool. And if you are afraid of getting the car stolen, if you go with a 86-87 you don't have clearance problems with the hood, so go to a wrecking yard and get a plain regal hood, put it on there and now you got just a plain old regal. Just keep your turbo hood for later use...

 

[pacecarta]

or just buy the 86-87 power master unit from from Autozone for about $150.

not to step off the subject here i wish they were still 150.00
but those AZ Powermasters are 347.00 + 61.00 core ,

whatever you get most will recomend changing over to the vac booster setup as found on reg regals ,cutlass and monte carlos and that can be done rather cheap if you can do the work yourself.

 

[Scott Long]

I have a brake system on my SC's that has a hydraulic motor and an accumulator w/ a pressure switch to tell when the accumulator is low and then the motor repressurizes the accumulator ball. My accumulator has a pressure leak so the motor cycles on and off more than normal. Last year I was in Virginia and the pressure switch went bad so the motor wouldn't run and then the brakes had no hydraulic assist. That was like stepping on a rock. I'd have to throw it in N and stand on the brake with two feet and swerve to even have a chance to stop. I coulnd't get the parts down there in time so I had to drive back to michigan in w/ no brakes. Rush hour traffic in D.C. sucked bad. Not to mention then snowy mountains on the PA turnpike. I have thought about converting my tbirds over to the standard tbird vacuum booster and mastercylinder. I don't know if the abs will still function properly though? I assume the GN had a similar system. I believe the pressure switch I ordered had a buick part number on it and it worked fine. It might be the same system. On my other SC I'm putting a big block 460 into I think that system is going to be in the way when I mount the engine so I will have to offset the engine or swap the brakes over.

Hopefully if I get a GN I can drive it for a while before worrying about the brakes. Do they give warning signs? My tbird will flash BRAKE and ANTILOCK if I hit the brakes to hard which means there is a problem with the system. I almost wrecked a few weekends ago in South Bend Indiana when some needle dick in a pickup pulls out in front of me so I slam the brakes and nothing until I was about an inch from his bumper and then the accumulator pressurized and I came to a halt. I was pretty pissed cuz there was traffic in the oncoming lane so I couldn't swerve anywhere. I hate that teves brake system, it was a decent design for the time but it doesn't age well and its expensive to repair.

 

[cool 84]

Re: either way you can't go wrong...

Originally posted by Zurn
I would go with an 86-87 myself. I have a friend who has spend $3k to get his 85' to run in the mid 13's. He has made a lot of mistakes along the way, since this was his first TR, but still, I just spent $1k and I hope to be in the high 12's this summer. He always talks about selling his so he can get an 86-87 so he can be faster. He tells me, "I wish I knew then what I knew now..." He didn't have a lot of money at the time and found a fast car for under $5k, so he jumped on it without doing research first. I know you are going to hear a lot of peoples personal preferences, so you will have to go with what you think will make you happy. I don't think there is any down side to getting a pre-intercooled car, speed cost money so how fast can you afford to go? I really like the older Buick body, like 78'. I've seen quite a few of the old sports coups go for under $1k and you could buy a totaled 86-87 and swap the drive train out and have a real sleeper car. That would be cool. And if you are afraid of getting the car stolen, if you go with a 86-87 you don't have clearance problems with the hood, so go to a wrecking yard and get a plain regal hood, put it on there and now you got just a plain old regal. Just keep your turbo hood for later use...

Sorry your friend spent 3K to go 13s. A hotair with the proper mods and tuning will go 13s for under $200. There's a local guy that has an 87 with a bigger turbo, injectors, downpipe, etc and barely went 13.9. The car was a basket case as isn't representative of the vast majority of 87 GNs and I would never imply it takes $3,000 to run 13.9s in an 87.

I admit that I would've bought an IC car if I thought I would take it to the level it's at right now. In the beginning I just wanted a 13 second car. Regardless, once I got rid of the shortcomings of the hotair, my car runs just as well as the 86-87 cars do mods vs mods and pumpgas vs pumpgas. My car was going 110mph on pump gas, no alky and that was ~14psi boost with about half the mods I currently have. Problem is you have to get a little creative since not as many parts are available for the hotairs. On top of that, hotairs are a little more trouble to work on. I would never get rid of my hotair but I would recommend starting with an IC car to anyone looking for cheap speed.

 

[Paul87gn]

If you do decide to go with the 86-87 and you'd like a set of 84-85 wheels I'd consider trading a set as long as the chrome was still in good shape.