What is a stage II engine?

R

Rodimus_Prime

Dirty Bird
Joined
Apr 30, 2009
Been on here for a while and I keep on seeing posts about this but I've never really saw any info outside this board on them. Is this an engine thats just bored out or something? Was it on another year other than 86-87. I know little outside of the 86-87/TTA stuff.

Whats the difference?, I looked around didn't see much other than classifieds selling parts for them.
 
Stage II blocks/heads, weren't a regular production item. They were developed by Buick Motor Sports (BMS) as a race item.
They were used in MANY different racing series including Busch Grand National series, IMSA, USAC, etc. etc. Primarilly during the early 80's.

They are a different casting than the stock blocks and are much stronger, with thicker webbing and interal, 4 bolt splayed main caps and other upgrades. Some had oiling systems which required dry sump setups, others had provisions for an internal pickup. Lot's of other differences also. The blocks came it two basic sizes, 3.8 or 4.1

The SII heads were the real heart of making big horsepower on these engines (800-1200+) They flowed incredible amounts (more than 300cfm).

Pose this question in the Stage II forum and you'll get some pretty detailed responses.
 
Still learning about them myself...someone plz correct me if I'm wrong but I believe stage 2 heads are held on by 14 bolts and the stage 2 block has the required 14 bolt holes....as opposed to the standard 8 holes for the typical 3.8 liter heads...I have read this helps prevent head lift which helps prevent blown head gaskets.
 
87Regal3.8SFI said:
Still learning about them myself...someone plz correct me if I'm wrong but I believe stage 2 heads are held on by 14 bolts and the stage 2 block has the required 14 bolt holes....as opposed to the standard 8 holes for the typical 3.8 liter heads...I have read this helps prevent head lift which helps prevent blown head gaskets.
Click to expand...


Yes, you're correct on the 14 bolt/stud holes.
Yes, it helps keeps the headgasket in place, "head lift"? IMHO it's a myth. Gaskets blow, all kinds of different reasons.
 
Dave, the reason I've been told gaskets blow is because the head lifts and allows the air/fuel mix in the cylinder to get past the gasket and that widdles away the gasket until there's no more left.

Now I have heard this obviously happens if you go lean in a cylinder, but I've also heard that it can happen if you run too much boost...in other words as I understand it, the stock production Buick block and heads can only hold down the head completely to the block under so much pressure, after that it begins to lift and allows the air/fuel mix to get by. And that the 14 bolt block/heads can hold the heads down to the block better under more pressure than the 8 bolt ones can.
 
87Regal3.8SFI said:
Dave, the reason I've been told gaskets blow is because the head lifts and allows the air/fuel mix in the cylinder to get past the gasket and that widdles away the gasket until there's no more left.

Now I have heard this obviously happens if you go lean in a cylinder, but I've also heard that it can happen if you run too much boost...in other words as I understand it, the stock production Buick block and heads can only hold down the head completely to the block under so much pressure, after that it begins to lift and allows the air/fuel mix to get by. And that the 14 bolt block/heads can hold the heads down to the block better under more pressure than the 8 bolt ones can.
Click to expand...


It's detonation that kills head gaskets, period...(barring bad installation). It can be cumulative (over time) or happen all at once. I've known a lot of guys over the years that were able to run 30+ #of boost with them little 8 bolt heads and do it safely. In the absence of detonation, adding another measly 25# of boost is hardly going to lift a head off it's mount with so much force holding it down.
Where does detonation come from? lack of octane/fuel...

It's still my contention that lifting heads at our power level is purely a myth, and I'll stand by that.

How do you suppose the super stock tractors can run in excess of 100# of boost and keep the heads on? They use stock blocks and bolt patterns, etc. Answer.... Tons of good fuel. Keep the cylinder quiet and gaskets stay put.
 
TurboDave said:
How do you suppose the super stock tractors can run in excess of 100# of boost and keep the heads on? They use stock blocks and bolt patterns, etc. Answer.... Tons of good fuel. Keep the cylinder quiet and gaskets stay put.
Click to expand...

Can't detonate a diesel, or the very least it's very hard to do. Most diesel blocks have the same bolt pattern/configuration as the Stage blocks.

Billy T.
gnxtc2@aol.com
 
Not that familiar with clearance issues with the TTA. The TTA uses different heads and I think headers than a GN. Anything could be made to fit but at what expense.

Is it worth it, that's for you to decide.

The Stage heads show their biggest potential in the higher rpms which makes them a disadvantage down low for the street. Yes, there are some that drive on the street with Stage heads.

Billy T.
gnxtc2@aol.com
 
Rodimus_Prime said:
Been on here for a while and I keep on seeing posts about this but I've never really saw any info outside this board on them. Is this an engine thats just bored out or something? Was it on another year other than 86-87. I know little outside of the 86-87/TTA stuff.

Whats the difference?, I looked around didn't see much other than classifieds selling parts for them.
Click to expand...

thank you for asking. Been wondering this myself.
 
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