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View Full Version : '86 GN Engine Rebuild Recommendations


Coelacanth
11-25-2004, 01:04 PM
Hello all, first post from a noob member!

This site & forum seems to be the definitive place for Buick GN information...well, I'm the proud owner of my dad's 1986 Grand National. It's in pretty much perfect condition, and only 92K km on the dash (Canadian car). It's never been winter-driven, and my dad takes very good care of his vehicles. The only problem is that he's driven it rather seldomly the past few years, and drove it like an old man drives it.

The last time I drove it, a few years ago, it was a shadow of its former self, barely even able to spin the tires without a brake-stand. The mid-range is all there, but you can tell the engine's probably pretty carboned up and sluggish.

I want to rebuild the motor and upgrade it somewhat. More for the street than the strip. I have about $5000 I want to put into the motor (Canadian dollars, so perhaps $4000 USD give or take).

What recommendations would you have to get the most bang for my buck? I've gone through some of the build recipes on this site, and here are some areas I'd like to work on...

-dual exhaust, possibly with headers; side-exiting exhaust tips
-Thrasher chip--seems like these are hard to find nowadays, the manufacturer no longer sells 'em
-rebuild existing turbo or replace with better...?
-ignition system recommendations?
-would the existing drivetrain work, or will things need to be beefed up, if it's mainly intended for street use?

I appreciate in advance your personal opinions and experiences, and specific suggestions to help me make a more informed purchase. I'm more of a "classic Mopar big block" guy, so my knowledge of turbos and post-70's engines is rather limited. :D

Coelacanth
11-26-2004, 02:22 PM
Hmm...*bump* 24 hours and 24 views, yet nobody has an opinion or a word of advice? :confused:

turbogn86
11-28-2004, 12:13 AM
well i did the same thing you are about to do, beefed up the motor for street/strip use, keeping stock appearance an not spending too much. we gave poston's a call an they helped us get the combonation we wanted. give them a call if ya can, based out of alabama, www.postonbuick.com i havent found a better source for a rebuild like this, ask to talk to tony an tell him your situation, he can tell you what he has an what combo works best with each part he has... only thing u DO NOT want from them is the 3 inch down pipe, terry houston down pipe is much better (an much easier to install.) hope this helps you.

gofstbuick
11-30-2004, 04:48 PM
How about not rebuilding the engine. Just replace the timing chaing and valve springs. Do a spring cleaning. Add a fuel pump, hot wire kit (or make your own) and adjustable fuel pressure regulator. Get a scantool and make sure your engine is in good tune. Do a transmission service and change the rear differential fluid (don't forget the posi additive). Make sure your cooling system is up to snuff. Also make sure your exhaust manifolds are not cracked and change the O2 sensor (GM GNX O2 sensor is a good sensor if you're not using leaded fuel). If you want to upgrade the turbo, use a TA49 or TE44 (and 36lbs or better fuel injectors). If you have some buds that can loan a chip to try, try some different ones and see what you like. Then make a chip decision or ask around for a chip recommendation. I hear Eric at Turbotweak is doing some wonderful chip programing. I have 009 injectors and like the Testa91 for alky or the Reds93 for alky. I'm using a Duttweiller neck intercooler and it works just fine. Purchase a cold air kit (from BuickGNBoosted) and maybe add a alky injection kit (or make your own). If your dad performed regular maintenance on the vehicle, IMHO I wouldn't open the bottom end up until something goes majorly wrong. The 3.8 is decently stout for your objectives and a new timing chain and valve springs may be just the ticket to getting back to a baseline.

Turbo2nr
12-01-2004, 07:50 AM
The last post is very good advice! Red Armstrong (quad air) chips are great, and he is a good guy to talk to. I would also hold off on the motor rebuild. I have seen plenty of Turbo Regals hit 200k on the stock bottom end. Stay away from Poston's Down pipe! Tranny rebuild should be needed soon. Talk to California Performance Trans. (Art Carr). I'd go a little bigger on the turbo, but thats just me. Like a TE-61, or PT54. Same price, mo'fun. Also ask Art Carr about a good torque converter for the turbo you select. Don't forget a new fuel filter! Have you checked out the spring cleaning section of this site?

Scott H.

kenmosher
12-01-2004, 12:07 PM
Hello all, first post from a noob member!

** SNIP **

What recommendations would you have to get the most bang for my buck? I've gone through some of the build recipes on this site, and here are some areas I'd like to work on...

-dual exhaust, possibly with headers; side-exiting exhaust tips
-Thrasher chip--seems like these are hard to find nowadays, the manufacturer no longer sells 'em
-rebuild existing turbo or replace with better...?
-ignition system recommendations?
-would the existing drivetrain work, or will things need to be beefed up, if it's mainly intended for street use?

Exhaust is a good thing, but side exit is kind ... well ... cheezy IMHO :) It's your car, so do what you think is right, but I'd probably just get one of the excellent exhaust systems like ATR, Poston, Torque Tech, or even Hooker make (stainless will cost a lot more than the aluminized Hooker, but will last forever). Skip the headers unless you really need to replace a bad set of stockers.... very little performance gain until car is really quick (high 10s or so)

Mufflers are important ... get something like an UltraFlow, Aerochamber, or PitBull style. They look like a standard turbo muffler, but are basically a straight through exhaust design. They work almost like an open pipe and tend to help fight the dreaded 2000-2500 RPM "drone".

Turbo - TA49 or TE44 is a great one step up from stock. You can go with some of the new GT series turbos for the latest in design and probably go a bit bigger with a slight converter change. If you go much bigger, consider a good torque converter that matches the characteristics of the turbo.

Chip - TurboTweak, Thrasher, Red's chips, Extender chips (Bob Bailey via Full Throttle), Jay Carter chips ... all good chioces

Ignition - stock is fine as long as coil pack is in good shape, new wires and plugs

Transmission - should be at least freshened up ... the stocker is sort of the "weak link" when you start making good power

Fuel System - good pump and filer are MANDATORY Something like a Quad Air XP pump or Walbro are important steps. If you step up in turbo size, you'll need injectors ... the new 60# MotoTrons from places like Quad Air, PT&E or Full Throttle are excellent pieces (I'm a bit biased, since that's my company, but they come with good pedigree from Mercury Marine Racing programs!)

Once you have a good foundation, just remember it's all in the combination .. think of the car as a total system, not a collection of parts. Make sure things work together well, since a good combo can sometimes make 1+1 = 3 as parts complement one another.

Have fun!

Coelacanth
12-10-2004, 09:04 PM
Thank you all for your advice! Even before reading your responses, I began to question whether or not I should do an engine rebuild, considering how well-maintained it currently is. I definitely will do some things to the exhaust and put in a cold air intake, and will pass on the headers. They're really not worth the small performance gain, for street use anyway. It's getting a set of brand new polished Centerline Auto Drags (these wheels just look so perfect on a GN!), 235/60R15's on the rear, stock size on the fronts (unfortunately Centerline doesn't make 16" Auto Drag wheels anymore, I really wanted to go with the tires used on the GNX's, but alas...).

I haven't decided whether to rebuild the existing turbo or upgrade it. What are the pros and cons of this? And as for alcohol injection, I haven't got a clue about that. Why would I move to alky, what are the pros and cons? How much would this add to the "engine upgrade" price?

I also will convert to the modern air conditioning refrigerant, but I have a friend who says he knows someone with a whole bunch of the old refrigerant...so if this is the case, that might save me several hundred bucks.

A tranny rebuild would probably be in order. I'll check the exhaust manifold for the dreaded cracking. Thanks again for the advice, and if you have any more tips about my above questions, much appreciated!

Turbo2nr
12-10-2004, 11:42 PM
Start saving money for tranny, and a future Powermaster (brakes) failure, then adding an alchohol kit is one of the biggest bang/for/buck things going. Adding 5-7psi on pump gas with alchohol. about $340(?). Get a bigger turbo! Sell stock, or keep it to sell car later. Stock parts on car will help with future value. I know i wanted a clean, stock car to start off with, so will most people.

Keller
12-11-2004, 05:37 PM
I haven't decided whether to rebuild the existing turbo or upgrade it.
You can use your stock one as a core for an upgrade to save some cash. Something like a TA49 and a set of decent injectors will really wake a bone stock TR up. Of course that starts getting off topic for this thread... Just make sure you have an aftermarket boost gauge, scan tool, upgraded fuel pump and such to go with it. Its a system.