4.1, 484# block, some questions.

[simple]

i have rather large valve heads (GN1R), i was going too build a 109 block that i have but am having second thoughts about the bore size in relation to valve size.

is there anything specific too the 109 block that wont work with the 4.1 block? (other then pistons)
what are estimated or round about limits of the 4.1 block as far as power goes?
what are known problem areas of the 4.1 block?
if there are known common problems, how are they aleviated?
will an RJC girdle work with a 4.1 block?
is it worth going too the larger bore block with my heads over the smaller 109?

TIA
Steve

 

[simple]

i've been searching and finding lots of info but if anyone has any thing they want too add from personal experience, that would be great
(will keep reading)

Steve

 

[fuzzyGN]

To answer in order of asked:
Everything is the same but the pistons and has a 14 bolt pan not 20.
Not sure but some in the 10's
a little weaker in the lifter valley, more prone to crack on the deck surface
Check the block for cracks and have the head bolt holes chamfered
A girdle for a 14 bolt (Hot air) block will fit fine
Pistons might (will) cost more but the added cubes is hard to beat. It is really a personal choice. Have to weigh the pro/cons and decide for yourself if you are willing to go through the effort.

 

[49-blues]

Interested in this also. Anyone run in the 9s or 10s with a 4.1 484 block? Whats the max cubic inches? I heard Weber has a stroker kit for this block.

 

[SHADOWII]

Have you read the tech articles on the turbobuicks.com web? They have a budget 4.1 build up. there is also one on gnttype.org. I am contemplating one next year, also, as i do more on the street than on the strip. :biggrin: I will be using the girdle, but not sure of crank assy. maybe eagle???

 

[ESP Products]

is there anything specific too the 109 block that wont work with the 4.1 block? (other then pistons)

Hello,
Cometic head gaskets will NOT work with a 4.1 block. Problem with the water passages sealing.
We do offer a 14 bolt engine girdle, w/ ARP hardware, for the 14 bolt oil pan. It will work on both 3.8 or 4.1 blocks.
I think the 4.1 would have a torque advantage, but I've seen some pretty torquey 3.8s too.

Hope this helps.

 

[simple]

Have you read the tech articles on the turbobuicks.com web? They have a budget 4.1 build up. there is also one on gnttype.org. I am contemplating one next year, also, as i do more on the street than on the strip. :biggrin: I will be using the girdle, but not sure of crank assy. maybe eagle???

yeah, i've read alot of info about the 4.1 blocks.
if i do one, i will build it just like the 109 i had in mind. girdle, forged pistons, forged crank, low boost lots of airflow.
the thing that makes me shy of them and i'm sure its what makes everyone else wheary of them is the thinner deck and crack prone area around the water jacket

maybe i'll just have the heads assembled and then sell them for the smaller valve GN1's and do the 109 block i have. tough decision.
if someone came in here and proved that they were making x amount of power and spinning x amount of rpm for x amount of miles/years with the 4.1 and it wasnt such a hit or miss thing with them. then it wouldnt be such tough a decision

 

[simple]

Hello,
Cometic head gaskets will NOT work with a 4.1 block. Problem with the water passages sealing.
We do offer a 14 bolt engine girdle, w/ ARP hardware, for the 14 bolt oil pan. It will work on both 3.8 or 4.1 blocks.
I think the 4.1 would have a torque advantage, but I've seen some pretty torquey 3.8s too.

Hope this helps.

cool, whats your opinion of the 4.1 blocks in general?
if you had too do it, would you go the 4.1 route or stick with a 109?

the heads that i have are about the only reason i am contemplating using a 4.1 block. its just not an easy decision, seems like the majority is that its a crap shoot with them

 

[ESP Products]

...forged crank, low boost lots of airflow.

This is why we did the ESP Twin Turbo kit.

I drove a customers car that spooled real quick (hyper-quick - as my son would say). I couldn't keep this car out of boost. I asked about the engine and turbo and he had no idea, he bought it that way. While installing our ESP frontmount to the car we noticed his oil pan only had 14 bolts. We looked further and saw it was a 4.1, stock block. I liked that car.
In the end the 3.8 is tried and true and the 4.1 has a reputation for losing head gaskets. There are fixes for the gasket and you can try O-ringing the heads. We have built stock 4.1 blocks before and had no problems. I believe the addition of a girdle will help the entire engine stay together. I think I'd give it a shot.

 

[MIB]

I talked to Brian at Weber Racing and he does sell a stroker kit for the 4.1L. I think my combo w/.40 over would be @268cu. :biggrin:

 

[49-blues]

What other gaskets are available for the 4.1? Is it possible to use a proven stage 2 head gasket like a detroit that jack cotton uses or other stage 2 that would probably hold up?

 

[ESP Products]

It's not the head gaskets; it's the bolts, or lack of bolts that limit the clamping power. The stage 2 engine has an additional 6 bolts per head. This is why they hold gaskets better.

Hope this helps.

 

[49-blues]

Could the 4.1 block be drilled for additional holes so it could use the stage 2 gaskets?

 

[ESP Products]

Money can make anything possible. But seriously, it's not cost effective. You would be better off with an aluminum block or finding a good stage block.

 

[simple]

i think i am going to do a 4.1 motor. but open it up too a 4" bore.
girdled, forged crank, forged slugs. studded.
i think it fits better with my goals of less boost with the heads that i have. i might need too change turbos tho what do you guys think?
TE45a, GN1R's ~20-22psi...

 

[49-blues]

Why not go right to a 70 BB @18-21 psi.?

 

[simple]

Why not go right to a 70 BB @18-21 psi.?

i would think but not sure that it would need 3600+ converter?
plus i already have the 45a and heads. and a BB70 isnt cheap new! but, it has crossed my mind