Better to rebuild the 3.8 or build a budget 4.1?

[baller760]

My car has 109,000 on the stock motor. I'm not concerned with putting a ton of power through it right now as I have to still finish rebuilding my suspension (come on Power Performance Motorsports, where is my front end kit???), and then I'm going to dive into the tranny, and likely the rear after that. My goal with the car is low 11's at first with my ta-60, but I'd like the motor to be strong enough to handle mid to high 10's for the future after the 60. My question is, is it less expensive to rebuild the motor with 2-3 main caps, a girdle, and a roller? Or is it a better idea to do a budget 4.1 build (TurboBuicks.com - Build a Budget 4.1 Motor!) like this article over at turbobuicks.com. I have searched and it seems pretty common for these 4.1's to do low 11's really easily with not a lot of stress on the motor, apparently.

What route would you guys go and I'm assuming the heads, and all the 3.8 stuff bolts right up so you don't have to run a carb or anything like that. Well, I guess if you had to do that then no one would run a 4.1 :smile:

 

[baller760]

bump, no one knows?

 

[sixgun86gn]

My car has 109,000 on the stock motor. I'm not concerned with putting a ton of power through it right now as I have to still finish rebuilding my suspension (come on Power Performance Motorsports, where is my front end kit???), and then I'm going to dive into the tranny, and likely the rear after that. My goal with the car is low 11's at first with my ta-60, but I'd like the motor to be strong enough to handle mid to high 10's for the future after the 60. My question is, is it less expensive to rebuild the motor with 2-3 main caps, a girdle, and a roller? Or is it a better idea to do a budget 4.1 build (TurboBuicks.com - Build a Budget 4.1 Motor!) like this article over at turbobuicks.com. I have searched and it seems pretty common for these 4.1's to do low 11's really easily with not a lot of stress on the motor, apparently.

What route would you guys go and I'm assuming the heads, and all the 3.8 stuff bolts right up so you don't have to run a carb or anything like that. Well, I guess if you had to do that then no one would run a 4.1 :smile:

I built a 4.1 with used forged pistons for around $800 for the complete shortblock.

Had a 218/218 flat tappet cam,used 4.020 bore pistons ( yep thats .055 over stock ) ported heads and te63 turbo.

I drove it one hour to the local 1/8 track and went 7.17 @ 96 on plain 93 and 16#.

Put a little 110 in it and cranked the boost to 20# and went 6.80.

Took it to the 1/4 mile and busted the trans...still went 11.20 @ 127.5 mph.

I like the 4.1.

 

[baller760]

So when you went to the junkyard to get the 4.1 you didn't have to pull the motor by yourself and disassemble the entire motor down to the bare shorblock did you? Because that would be a pain with the heat and all. I'm sure they must have some mechanics on the scene that would take the car and strip it down to the block for you?

 

[sixgun86gn]

So when you went to the junkyard to get the 4.1 you didn't have to pull the motor by yourself and disassemble the entire motor down to the bare shorblock did you? Because that would be a pain with the heat and all. I'm sure they must have some mechanics on the scene that would take the car and strip it down to the block for you?

Bought a bare 4.1 block from a boardmember for $150.
Rods from another for $40,.020/.020 crank $200,
used pistons $150,bearings $50,cam $69,lifters $30,
timing chain $30,
machine work (vat,bore,hone,cam bearings,freeze plugs) $85.


Assembled myself and installed heads,intake,etc from my 3.8.

You do need a 14 bolt oilpan and matching timing cover,I got mine free,but they shouldn't be too expensive.

BTW,that motor made 500 RWHP/500 RWTQ @ only 20#.

 

[TURBOPOWERED68]

Please excuse my ignorance
But
Would the stroker kits for the 3.8s fit this thing?
And how would it add up?

 

[Boost231]

stroker 4.1 is the only way to go. comes out to a 4.5

 

[petesgn]

stroker 4.1 is the only way to go. comes out to a 4.5

interesting hmmm

 

[sixgun86gn]

Please excuse my ignorance
But
Would the stroker kits for the 3.8s fit this thing?
And how would it add up?

Yes the stroker kit would work,so long as you got the larger 4.1 bore pistons (around $800 themselves)

after the balancing for the heavier pistons and metal added to the crank,I would bet its costly.

I just used the stock 3.8 balancer and flywheel no balancing,no caps,or girdles.

I think where the 4.1 really shines is where the larger bore unshrouds the valves as well as the extra 20 cubes under boost are like adding 100ci to a NA motor.Instant boost too.

 

[baller760]

So to bore it out to a 4.5 what size pistons and what crank would be needed? Wouldn't the pistons have to be custom? How much of a pain is it to machine the RJC girdle to a 4.1 block?

 

[sixgun86gn]

So to bore it out to a 4.5 what size pistons and what crank would be needed? Wouldn't the pistons have to be custom? How much of a pain is it to machine the RJC girdle to a 4.1 block?

.030 overbore and 3.625 stroke (stock is 3.40)All forged 4.1 pistons are custom,only hypers are available off the shelf for $200.

RJC makes a 14 bolt girdle that can be used on early 3.8's and 4.1's.

 

[bison]

The blocks need a lot more attention than the 3.8. They are prone to cracking on the deck and it is not worth it to spend a ton of $ on one imo. You should be able to run high tens reliably if there is no detonation and anything beyond that is a roll of the dice.

 

[boostingbuick]

Well , well. I run the 4.1 and love this motor. It has gone 10.98 at 128 on pump gas. Really. Makes my 70 turbo spool fast and makes good off boost torque. I have an ESP girdle on this with stock caps. Untill I ride in a stroked 3.8 I will stay with my 4.1. Just my 2 cents.

 

[BOSS 6]

engine tech

build the 3.8 and if i was you i would look at another turbo ta60 doesnt make power real good.