86 GN engine

marc1122

New Member
I have an 86 GN engine. I got it from a friend who has had it for years. He wrecked the car with 30000 miles on it. The car was totaled. He bought it back and pulled the drivetrain. It sat in his shop until last month when I bought it. The shop is climate controlled and he rotated the engine thru the years.
I am building a project and plan on using this power plant. I would like to achieve 400 to 450 HP. I plan on opening up the engine to some extent for replacing gaskets and seals since it has been so many years. My question is what modifications do I need to make to the engine to achieve this HP? I am have dealt with and built mostly small block fords and Chevys that are carbureted. This is the first turbo v6 I have had.
I appreciate any input.
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
All you need is a good pair of heads and a convertor...and know how to tune. Build is in my sig...and it does it all day long on low boost, easy launch and an easy tune.
 

marc1122

New Member
All you need is a good pair of heads and a convertor...and know how to tune. Build is in my sig...and it does it all day long on low boost, easy launch and an easy tune.
I assume you are talking of after market heads?
What company makes a good set?
Thanks
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Off the shelf iron Champion heads. I have a gentleman in Montreal that did mine.
 

1986 Buick GX1

GX1 #001 [The One and Only]
I assume you are talking of after market heads?
What company makes a good set?
Thanks

Translation...... a good set of heads = ported heads with larger valves, stock or aftermarket.

Off the shelf iron Champion heads. I have a gentleman in Montreal that did mine.

Translation........ I have a gentleman in Montreal that did mine. = He has a guy that ported and installed larger valves in his stock heads. I think. Lol
 

SCOOBY DOO

I'M NOT A MONSTER, I'M JUST AHEAD OF THE CURVE!!!
Exactly. He's a Buick guy that's been doing them from Day 1 and has a flow bench.
 

Jerryl

Tall Unvaccinated Chinese Guy
Ported heads definitely help, but 400-500 fwhp (big range btw) can be done with stock unported heads.

Regardless of ported iron or aluminum heads, the fuel system, converter, transmission, electrical and tune should be on point. Don't underestimate the learning curve transfering from NA carb to boosted EFI Buick.
 

Jerryl

Tall Unvaccinated Chinese Guy
For the power goal you're looking for there's no way in hell I'd recommened breaking the factory head gasket seal.

Valve springs, timing set, 60' TT chip, and alky. And you're done.
Agree. I would like to add power logger and wb sensor (scanmaster minimum), fuel pump with HW, right size turbo, IC and free flowing exhaust, solid ignition and fuel system, and a tune, for target FWHP.

Don't take your knowledge for granted because many newbs may not know what it takes.
 

V6sleeper

Well-Known Member
I wouldn't pull the heads for 400hp either, the factory seals are like cement at this point, wait till you crack a piston then go for 550hp on a rebuild w/ported irons.
 

jasjamz

THS Racer
I knew this debate would start. Ported Irons vs High boost stock heads.
First, you need to replace the valve springs. If you can get this done on the stand with the heads on... great. You will want to upgrade the timing chain and gears as well. Post pictures of the engine and head bolts. It may not have the GM seal. If not, I agree with ported irons and a 206/206 Hyd roller cam. 400-450 hp is easy for some, impossible for others then you have the average guys in between. Find a good go to guy to communicate with so you don't get 5 different opinions for every question.
 
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