GM 3.8 litre v6 specifications

[ozpolly]

I am looking at fitting a GM 3.8 litre v6 to a 15' boat i am designing. But i need to know some important specifications .

The distance of the underside of the sump to the engine mounts?

From the engine mounts to the top of the engine?

The overall length of the engine?

From the centre line of the crankshaft, how low is it from the engine mounts?

And the overall width and length.

if anyone can help me with any of these questions it would be a big help..
cheers

[whitepointer23]

hello ozpoly, why don't you go to the nearest wreckers and get your measurements off an engine, i assume you will be marinising a commodore engine, you can also buy a cheap haynes manual for the specs.

[Frosty]

Im sure it would be a great help for a job like that but these guys here are like you and me, no one will be able to answer those questions.

These are the problems you come up to on a job like that.

[powerabout]

its all in the OEM drawings of a Mercruiser should your engine be using the same sump and mounts
Every dealer should have them or certainly get a drawing
or www.gmpowertrain.com and send an email

[whitepointer23]

its all in the OEM drawings of a Mercruiser should your engine be using the same sump and mounts
Every dealer should have them or certainly get a drawing
or www.gmpowertrain.com and send an email

he is using a 3.8 holden v6, different to the chev mercruiser 4.3.

[judgegage]

WOW...Holden...You Aussies with your Road Warrior jokes...JK.

OZ, The dimension are hard to find. I'm with WP23 get the measurements you need from a wrecker (can only imagine how many were made WW). That engine was converted for marine use (used in a lot of FWD cars), look for conversion parts... that should get you close to the dimensions you need on the bottom.

I say this because you want a rear sump oil pan.

[powerabout]

oops
then try www.kmrolco.com
they sell marinising gear so maybe they have dimensions
( thats an Australian built Buick for those foreigners)

[ozpolly]

thanks for the help. kmrolco was very useful

[whitepointer23]

WOW...Holden...You Aussies with your Road Warrior jokes...JK.

OZ, The dimension are hard to find. I'm with WP23 get the measurements you need from a wrecker (can only imagine how many were made WW). That engine was converted for marine use (used in a lot of FWD cars), look for conversion parts... that should get you close to the dimensions you need on the bottom.

I say this because you want a rear sump oil pan.

they are an aus engine originally designed from a buick, but the block is different. holden made a new block with both banks in line not offset like buick. imo it is the wrong choice. i would use a hot 4 out of a jap car, you then only need 1 manifold and you have a good choice of performance engines from jap importers.

[powerabout]

so the conrods have s bends in them so they dont hit each other?

[triman692003]

A bloke in Melbourne put a 3.8 engine on a Mercruiser Alpha 1 drive. Had to make all his own manifolds, coupler etc but it went like a dog shot in the bum!!! Far better than the 470 it replaced.

have a look at;

http://forums.iboats.com/showthread.php?t=369819&highlight=4bait

[DCockey]

they are an aus engine originally designed from a buick, but the block is different. holden made a new block with both banks in line not offset like buick. .....

The 3.8 / 3800 engine was redesigned several times during it's long production, including the change in bore centers relative to the crankshaft. I'm certain that the Holden design was not unique but shared with north american built engines. There were both transverse (FWD) and longitudinal (RWD) versions of the 3.8 and 3800.
http://en.wikipedia.org/wiki/Buick_V6_engine

[judgegage]

DC, I looked at that Wiki page and was thinking about the 3.8/3800 I have worked on and 2 I've owned, I could not remember any of them having a bank offset. I thought there may have been some confusion with the even fire and odd fire versions of this engine.

[DCockey]

Even fire vs odd fire is only affected by the crankshaft geometry, not the block. The original Buick V6 was essentially 3/4 of a V8, and the V6 used a crankshaft with shared rod bearing journals, the same as a V8. The rods for opposite cylinders shared a common journal on the crankshaft which resulted in uneven firing intervals. Around 1977 GM changed the crankshaft to one with offset journals so that the firing intervals were even.

The bore offset in the earlier engines was relatively small, 5 mm or so, and may not have been very noticeable.

[whitepointer23]

The 3.8 / 3800 engine was redesigned several times during it's long production, including the change in bore centers relative to the crankshaft. I'm certain that the Holden design was not unique but shared with north american built engines. There were both transverse (FWD) and longitudinal (RWD) versions of the 3.8 and 3800.
http://en.wikipedia.org/wiki/Buick_V6_engine

you are right, i did a bit of home work and found out our engine is indeed the american engine with some intake mods, sorry for giving out the wrong info, i read it in a car magazine years ago that it was an aus engine. the change in bore centers just happened to be introduced at the time holden started using it.

[powerabout]

Even fire vs odd fire is only affected by the crankshaft geometry, not the block. The original Buick V6 was essentially 3/4 of a V8, and the V6 used a crankshaft with shared rod bearing journals, the same as a V8. The rods for opposite cylinders shared a common journal on the crankshaft which resulted in uneven firing intervals. Around 1977 GM changed the crankshaft to one with offset journals so that the firing intervals were even.

The bore offset in the earlier engines was relatively small, 5 mm or so, and may not have been very noticeable.
The bore offset would be the thickness of the conrod and for US engines left bank forward
The only engine I know that has right bank forward is/was the Holden 253/308 as purpose built for right hand drive cars

( not imposible to build and engine without an offset but why would you you would have the rods not centered in the pistons and need offset rockers to get to the pushrods or do OHC and share big ends like a Rolls Merlin)

[DCockey]

The bore offset would be the thickness of the conrod and for US engines left bank forward
The only engine I know that has right bank forward is/was the Holden 253/308 as purpose built for right hand drive cars

( not imposible to build and engine without an offset but why would you you would have the rods not centered in the pistons and need offset rockers to get to the pushrods or do OHC and share big ends like a Rolls Merlin)

Different bore offset.

The bore offset of the early Buick V6's which has been mentioned was an offset of the cylinder centerlines relative to the crankshaft centerline such that the cylinder centerlines did not intersect the crankshaft centerline.

[powerabout]

Different bore offset.

The bore offset of the early Buick V6's which has been mentioned was an offset of the cylinder centerlines relative to the crankshaft centerline such that the cylinder centerlines did not intersect the crankshaft centerline.
thanks for the info
next question, why did they do that?
trying to fix the vibration or something?

[DCockey]

I know of two reasons given for offset bores. One is packaging internally within the engine. The other is so that the expansion strokes take longer than the compression strokes. The benefits of the latter are small, and on a V engine would require cylinders to be offset asymmetrically. Offsets of the magnitude generally used would have only a small to negligable effect on engine vibration.

The Buick V6 geometry goes back to the Buick aluminum 215 cubic inch V8 which was introduced in the 1961 model year and designed around 1958. My guess, and only a guess, is the cylinder banks were offset outwards to provide more space in the engine "valley".

[srimes]

Y'all are confusing engines here. The Buick 3.8 v6 is COMPLETELY different from the GM 3800 (series 2). Yes they're bot v6 engines that displace 3.8 liters, and they came in Buicks, but that's it. The 3.8 is a 90 degree motor, and the 3800 is 60 degrees.

The 3800 is great. Compact, powerful, light. Great motor.

[DCockey]

Y'all are confusing engines here. The Buick 3.8 v6 is COMPLETELY different from the GM 3800 (series 2). Yes they're bot v6 engines that displace 3.8 liters, and they came in Buicks, but that's it. The 3.8 is a 90 degree motor, and the 3800 is 60 degrees.

The 3800 is great. Compact, powerful, light. Great motor.

The 3800 is a 90 degree, pushrod V6. It was directly developed from the early 3.8 Buick V6.

You may be confusing it with one of the other 60 degree V6 engines GM has built.

[srimes]

Ok my bad. It is a 90 degree block, but it uses the 60 degree bellhousing. That's where I got confused. Pretty much everything is different from the older ones (parts don't swap).