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Resident Idiot
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Discussion Starter · #1 ·
Someone with way too much time needs to try this..

Find a decent (4) bbl. 4.1 motor in a junk yard.

Clean it up, check the bearings.
Install stock 3.8 turbo cam (if it's different/needed).
Install a new timing set.
But all in all, leave the short block as is.

It will have 8:1 compression, the "desireable" rods, the "turbo" crank, correct heads and factory Buick pistons. (strong right?)

Install into a GN as usual. Intake, valve covers, exhaust manifolds and everything else would be of the GN weaponry of course. Run turbo oil return line into the mechanical fuel pump block off plate.

RUN IT!

What's to say this motor will be any weaker than a regular 3.8?

Are we just going to assume this will not work, or will someone try this?

I think it would be fun and educational, not to mention CHEAP!

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Stock Turbo, Stock Heads, Stock CAM, V4, MSD50's, TH DP, JayJackson 62mm TB, 16position MaxEffort Chip. 3750# with Driver
12.35 & 108.39 Street Trim
11.92 @ 111.77 Race Ready
mailto:[email protected][email protected]</A>
 

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Not that he has too much time on his hands (hardly), but Nick Micale is in the process of doing that. Stay tuned.

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Resident Idiot
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Discussion Starter · #3 ·
I knew it wasn't a crazy idea.. keep us posted. Man, now I am wishing this 4.1 I have here wasn't all torn apart.

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Stock Turbo, Stock Heads, Stock CAM, V4, MSD50's, TH DP, JayJackson 62mm TB, 16position MaxEffort Chip. 3750# with Driver
12.35 & 108.39 Street Trim
11.92 @ 111.77 Race Ready
mailto:[email protected][email protected]</A>
 

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**** Not that he has too much time on his hands (hardly), but Nick Micale is in the process of doing that.

Is he using stock type pistons?????
I could do this with one of the blocks I got at the yard last week!I am just afraid to blow the eng and destroy the trany and hurt the car!
Mike, you are making me think about it though!!

any one with more info on the pistons??

how about info on a 4291 4.1 block??(no mention on gnttype.org)
Thanks
Chris

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Original owner
PTE 44,THDP,868's,port matched heads/intake,ported stock intercooler,14in K&N,every thing else stock!!
Best 1/8 7.87 @87.4 mph with Pep Boy Tires and 2nd slipping!!!!
Eng and trany apart...will be back soon!!
 

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I finished tearing down the 3.8 this afternoon,then took a look at the stock 4.1 piston,the .40 4.1 piston and the 3.8 turbo piston.
The st. 4.1 piston looks pretty weak.
The .40 4.1 is a little beefier(just some cheap cast piston I am sure)
It looks like my 3.8 is going to need to be punched out so I may throw the 1981 .40,4.1 together and see what happens!!

I don't know how to post pictures,but I took some shots of all the pistons side by side..if any one is interested I could e-mail them to you.
Just throwing a little more into the whole mess
Chris

------------------
Original owner
PTE 44,THDP,868's,port matched heads/intake,ported stock intercooler,14in K&N,every thing else stock!!
Best 1/8 7.87 @87.4 mph with Pep Boy Tires and 2nd slipping!!!!
Eng and trany apart...will be back soon!!
 

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43,735 Posts
Phil Verhaeghe put a lot of effort into building 4.1's....he wrote this up a few months ago.


____________________________________________


Hey guys. I hope all is well. Haven't talked to many of you in a long time.

I put together a few tips on building a 4.1. I've been getting a bunch of
email about them and havn't had time to answer it all of the past several
months. I apologise to the guys I didn't get to. Here's my effort to make up.
I hope it helps out some. If I left something out, I'll try to be better
about answering emails...
Well take it easy.

Phil Verhaeghe

4.1 Recipe....

In an effort to help you guys out on building a 4.1 or whether or to build a
4.1 production block (NOT a stage block), I put this little FAQ together to
answer some common questions I get.

First, if you have a GOOD 3.8 block from an 86-87, then stop thinking 4.1 and
build your 3.8! The advantages to running a 4.1 are definitely apparent, but
hardly worth the price of custom pistons if it can be avoided, IMHO.

So despite my advice, you've decided to build the 4.1. You want the low end
torque your 3.8 seems to lack. Here are a few things that I've found after
building SEVERAL 4.1 motors. These observations are from my experiences. Like
anything else, there will be different opinions out there;-)

Block selection: you've got 4 years to choose from, 80-84. 81 and 82 blocks
have small oil pump feed gallies. The 83 and 84 blocks have the same size
feed as the 86-87 T3.8s. This means that if you do pick up the earlier block,
you need to machine that galley to the larger size to ensure adequate oil
flow. You must find a block that has no cracks on the deck surface. MANY of
them do. I found that a lot of the castings were poor on the 4.1 so sonic
checking is a must for the long haul. You'll probably have to go through a
couple blocks before you find one that has consistent casting thickness
throughout the cylinder walls and deck surface.

Block prep: You will first notice that you need an oil return line for the
turbo. I did the tap and drill method in the stock 3.8 location. A better
suggestion would be to run the return line to the oil pan. Think about a good
strategic place for a boss to be welded to the pan (i.e. No interference with
the crank). The advantage here is to keep the blistering hot oil away from
the seemingly vulnerable cam and to avoid that oil dumping on the rotating
masses below. You should polish out the casting slag in the bottom of the
lifter valley. That is a common place for cracks to start. Anything beyond
that is at your own discretion. Use head studs. They put less load on the
vulnerable 4.1 deck surface. Obviously you would be wise to run at least the
center two mains in steel. I like girdles too. The less stress in any engine
casting the better for that long haul… Go ahead and "surface" the deck. This
means that you're not removing any notable material, but you're putting a good
finish on it and taking out any inconsistencies from past heat warping, etc.
Do the same to your heads. Stock T3.8 heads will work fine. Keep in mind the
stock T3.8 heads are already undersized, and a 4.1 flows about 10% more air
so they will be that much smaller. Will they hurt performance, no, but they
may not allow you to utilize the extra cubes fullest potential. I bore to a
full 4.000" (.035 over). Note that this is the same bore is a Chevy 350. Ring
selection is enormous for this bore. I like to keep my stuff as easy to find
as possible, hence the Chevy pin and bore size. Also, 4.000" is the MAX bore
for the 4.1 production block. So you might want find two blocks to prepare
for the unexpected.

PISTONS: I get a ton of questions about the magic piston to install. There
isn't one. The worse that you can do is buying the Speedpro "hyperujunkit"
pistons. They may be fine in that 455 in the your Electra, but they have NO
business in a turbo charged anything! I don't have available piston specs so
please don't ask;-) With minimal homework you can find the info you need to
build the piston of your desire. ASK THE LIST. You'll need to know compressed
gasket thickness, desired compression ratio, compression dome cc, etc. Call
JE or Wiseco for your slugs. Keep this in mind. For the most part, lighter is
better. Full floaters are better than press fit pins. Thinner rings create
more sealing power and less friction. If you go full float then use the same
size pin as a small block Chevy. You will have an almost infinite weight
selection in pins that way. Higher compression means MORE torque down low,
BUT it also means that you will run into tuning nightmares that will keep you
up weeks at a time.lol. Believe me I know. I started at about 9.5:1 and ended
up at 9:1, which is still too high for a car that runs primarily on pump gas.
If you're going to the track and running good gas, that boost in compression
WILL be an advantage. If your livelihood is smoking Stangs on Amoco 92 at
stoplights, then stay with 8:1 not to exceed 8.5:1. You'll also find, as I
did, there are few chip burners out there that want to or know how to burn
chips for high compression. This being the case, you will have to teach
yourself hacker skills or buy a Felpro;-). Another very important detail…
Never buy just 6 custom pistons. JE and Wiseco have minimum orders of 4. This
means that when something catastrophic occurs in your motor and you burn an
$85 piston, you can't just buy 1. You have to buy 4! So, buy at least 1
extra, and if you're smart you'll buy two more.

Rings: I tried both Total Seal Race rings and Speed Pro Race Molly rings.
They both seemed to seal adequately. Neither seemed to better than the other.
I ran 1/16" compression rings and 3/16 oil rings. These size rings are easy
to come by.

Crank: Any good T3.8 crank is fine.

Head Gaskets: Felpro 1000s are the way to go. They have a 4" fire ring so
they are perfectly suited for the 4.1. I have never blown a 1000. The "key"
to keeping gaskets where they're supposed to be is block and head prep. Both
sealing surfaces MUST be surfaced with the right finish, free of "cupping",
and oil/chemical free. Keep in mind that a rough sealing surface is not
necessarily the best surface for HGs to seal on. A Felpro tech will be able
to tell you over the phone what finish the 1000s require. The studs I
mentioned earlier will also help to keep a good seal.

Cam: I have tried a LOT of cams in the 4.1. The result was every time I went
bigger, the car felt and went faster, period. The 4.1 flows about 10% more
air so the big cams for the 3.8 aren't so big on the 4.1. The biggest flat
tappet I ran was a 218/218 @ .050 while the largest roller I ran was a
214/210 @ .050. I sacrificed some duration with the roller but gained ramp
speed and lift. In theory the roller would net more torque and a flatter
power band, but the motor pulled extremely strong from idle with the 218/218
as well

Turbo/Injectors: Again, 10% more air requires 10% more fuel. Keep this in
mind when ordering a turbo and injectors.

Exhaust: Again, more air, means better exhaust. If your exhaust is marginal
on the 3.8, then it will be proportionally worse behind the 4.1.

I think that about covers it. The rest of the typical bolt ons apply. Front
mounts, front cover, etc. that bolts right up from the 3.8. Obviously, the
motor is only limited by the amount of money you want to put into it. While
it is NOT entirely necessary to do these mods I mentioned (which are minimal)
to run the 4.1, they will make better utilization of the larger cubes. I hope
I haven't forgotten anything. Good luck!


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Steve Wood

86 GN bought new, 87 T-type-81 El Camino with GN drive train-basically stock 86, 94 Caprice 9C1, 69 SS396 Camaro Convertible
 

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Originally posted by Orlando_87GN:
Someone with way too much time needs to try this..
Find a decent (4) bbl. 4.1 motor in a junk yard.
Clean it up, check the bearings.
Install stock 3.8 turbo cam (if it's different/needed).Install a new timing set.
But all in all, leave the short block as is.
It will have 8:1 compression, the "desireable" rods, the "turbo" crank, correct heads and factory Buick pistons. (strong right?)
Install into a GN as usual. Intake, valve covers, exhaust manifolds and everything else would be of the GN weaponry of course.
RUN IT!
What's to say this motor will be any weaker than a regular 3.8?
Are we just going to assume this will not work, or will someone try this?
I think it would be fun and educational, not to mention CHEAP!
Depends on what your intentions are for the motor? Street driving, low boost [16psi], should do ok. My intention to to do some exteme testing with a 4.1 for street/strip, high boost [25 psi], lots of torque and stay togetherness!

So, pistons are a must, stock 4.1's will never do. All 4.1 turbo pistons are basically custom and $100 or so each. Got to have steel caps which mandates line bore/hone and main studs. Assembly must be balanced. Stock heads, no way. Bigger bore cries for more air and the unshrouded valves can flow lots better. A few other "items" will be included to help this also become a Buick "torque monster"!

Soon as I finish the 2 GN's waiting for motors, this will be the next project. The car this will go into is planned to be the test mule for the "next generation" turbo
V-6 alum block and heads from TA performance later this year.

The info Phil V. put out on his 4.1 experience is very helpful and is an excellent guide to building one.

------------------
Nick Micale
3334 W. Marconi Ave
Phoenix, AZ 85053
602-866-9908
 

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SCONE WIZARD...
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704 Posts
Hmmm,
I actually have been tossing that idea around for the last few months! I know of a junkyard round here with a few 4.1s... Gonna hit them yards once it warms up and do some TR crank hunting.. and planned on keeping one of the complete 4.1 engines...

Does anyone know if you can buy a hypereutectic piston for the Buick 4.1 L motor? If so those would be plenty strong for what "I" want to do...

For the most part... I want to see how much of a gain there would be in street trim with the extra displacement of a 4.1, quicker spool up of the stock turbo due to the extra cubes and what not... If there is a company that makes Hyper pistons I will try it, but if I am stuck witrh making custom pistons, or using stock 4.1 pistons, i'll sell the block.. and build my extra turbo motor Ihave here...

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1987 Limited Turbo T,
12.28 @ 106 MPH w/a 1.62 60'
My 1987 Regal Limited Turbo T page..
 

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Resident Idiot
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11,462 Posts
Discussion Starter · #10 ·
Call Summit and order the Federal Mogul Hyper Pistons for the 4.1 ..

H471P20 are .020 over
H471P30 are .030 over
H471P40 are .040 over (the ones I got)

Rings are E408K (20, 30 or 40 as well.)

(6) Pistons are $146.34 with pins
(1) Set of rings are $57.39

Here are the specs on them, and they should yeild very close to 8:1 CR.

CH 1.807
.276 deep dish by 3.215"

I have them on the way, and plan to use them in my 4.1. I'll let you know if I melt it, but I believe things should be just fine.. At just over $200 for the right piston and rings, they are so cheap I have to find out for myself.


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Stock Turbo, Stock Heads, Stock CAM, V4, MSD50's, TH DP, JayJackson 62mm TB, 16position MaxEffort Chip. 3750# with Driver
12.35 & 108.39 Street Trim
11.92 @ 111.77 Race Ready
mailto:[email protected][email protected]</A>
 

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I have two 4.1 blocks sitting on my bench now .(a 291 and a 484 block)and other than some MINOR ribbing , I don't see a difference between the two.BUT, look at my 109 block I see some key differences/improvements. the lifter valley is the obvious one ,another is the extra casting added in the webbing on the #2 and #3 main bearing .(where they are attached to the block..if that makes sense...)
I would think hard about a 'stock' build up with a 4.1 block .(by stock I mean stock mains no girdle...)I know I have thought about throwing the 281 block in my car but I think I will 'throw' together my 109 block(which has SG1 cast in it) and run my 25psi with no fear.....BUT I think I am going to *build up* one of these 4.1L eng for next year..........
sorry Mike........hehe
Chris


------------------
Original owner
PTE 44,THDP,868's,port matched heads/intake,ported stock intercooler,14in K&N,every thing else stock!!
Best 1/8 7.87 @87.4 mph with Pep Boy Tires and 2nd slipping!!!!
Eng and trany apart...will be back soon!!
 

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Registered
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I forgot the main caps them selves,THEY have some ribbing on the 109 block too....interesting.....
Chris

------------------
Original owner
PTE 44,THDP,868's,port matched heads/intake,ported stock intercooler,14in K&N,every thing else stock!!
Best 1/8 7.87 @87.4 mph with Pep Boy Tires and 2nd slipping!!!!
Eng and trany apart...will be back soon!!
 
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