Hey guys and girls, I am learning about Buick GN's, and I am ready to buy one very soon, I have one that is nearby that I am interested in. I know that there is almost a 1.5 sec. difference between the i/c'ed ('86-'87) and the hot-air ('84-'85) GN's in the 1/4 mi. But if you add an i/c (such as the Spearco kit, or will the '86-'87 stock i/c fit?) to a hot-air GN, will it perform as well as an '86-'87? This is very important in making my decision. What are the hp/torque ratings on these cars (does it change from '84-'87?), I believe it's 245hp or so.
If I can spend the $1000 bucks on an i/c kit to make this '85 behave like an '86-'87, then that would work out perfectly. Thanks a lot for your help.
In my opinion, upgrades to the 86/87 cars are much easier than to the 84/85 cars. While adding an intercooler to the latter will make up much of the HP difference, future modifications are still more difficult. I'll leave it up to the 84/85 owners to add their views to this. Regardless, the 'hot air' cars are strong performers and usually provide a very good bang for the buck.
See http://www.gnttype.org/general/product.html for the power figures. Note that the difference in 86 and 87 advertised numbers is considered to be strictly administrative, as the two years are mechanicaly identical and the HP change is in step with keeping the HP of any GM vehicle under the figures cited for the Corvette.
Thanks for the reply. That's basically what I wanted to know, if the '84-'85's (with i/c) had the same amount of potential as the '86-'87's. I might get it anyway, it sounds like a good deal.
'85 GN
new.... paint, motor, tranny, turbo, brakes, tires, seats redone
170k on the frame of the car
How much would you pay for this car? I will try to check it out soon, it's an hour away, so I've gotta make time.
I can't really say what a good price would be, I paid $4500 for a 23K mile 85 with rough paint (sat outside its whole life) and that was in 1997.
86/7 cars are EASIER TO MODIFY TO GO FAST CHEAP.
You CAN get 84/5 cars to run with the 86/7 cars performance wise with just takes spending the $$ in the right place.
The areas I found that needed the most attention are the headers, intake and turbo.
My combo is as follows, I decided on the 109 block to rebuild with as my goals are pretty high.
-1986/7 "109" block
-J&E Pistons (.030 over)
-.010/.010 cut Stock Turbo Crank (Nitrided)
-Stock Rods (Nitrited)
-Stock Heads
-208/214 Isky Cam
-Steel Main Caps
-TA-54 Turbo with .85 Exhaust Housing
-Turbo Motion V2 Intake with modified 86/7 IC
-ATR 84/5 Headers and 2.5" DP
-55# Injectors
-Modified ECM
-MAF Translator with 3" LT1 MAF
-9" Art Carr 3500 Stall converter
-Walbro 307 FP
-Martone Adjustable Regulator
While that may look like a large list, its really not too much more than I'd do to a 86/7 to get where I want to go.
The stock intake on the 84/5 cars is restrictive. It produces great low end power, especially with the small turbo that comes stock with the car. Top end wise, it will choke. Jay at TurboMotion (look in the vendor list)has reworked the stock intakes to get better flow than a 86/7 intake with better distribution. You can get them in IC'd and non-ic'd version.
The stock headers, up pipe and down-pipe are also not as good as their 86/7 counterparts, the ATR pieces are nice.
With the above combo my car went 12.1@117.3 at 23# of boost in Las Vegas a few weeks back. That was at 3500ft elevation, NHRA correction factors low that to a theoretical 11.6@122). My car would have ET'd a whole lot better if my car had a posi and slicks, but the MPH shows low 11 sec potential.
This winter I am going to a 70 Turbo, DFI, front mount IC and ported heads. I am hoping for 128-130mph out if it when i'm done tuning.