All things being equal, how much of an edge does a 4.1 have on a 3.8, performance wise?
Are there any blocks or heads that should be avoided?
About 30 cubic inches!
and now for the second part of the question, what HP difference?
That depends where you are?
One HP per cubic inch, 2 HP per c.i.or ?
You do the math!
Thanks Carl, knew I had almost 30 c.i. from somewhere!
Another BIG advantage the 4.1 has over a 3.8 is the
larger bore unshrouds the valves for much better
breathing. For those that can remember when Buick
went from a 400 c.i. V-8 to a larger bore 455, torque
and HP were greatly improved with all else being
the same.
A few years ago on the board, one of the members
wanted to see how much HP a 4.1 would handle
from a strength point of view. He found out on the
dyno it self-destructed at 700 HP!
A big problem with the 4.1 is the head gasket reliability.
Just as Carl pointed out, a weaker block deck contributes
to this. Also, a lack of a decent head gasket also has
been a deficiency. The Felpro 1026 has been the only
choice for a max bore 4.1 and the fire ring is not up to
the cylinder pressures of a turbo motor. We now have
the all steel Cometic gaskets that will work much
better.
My limited experience with a 4.1 using good flowing heads,
it can develop about 600 HP at less than 25 psi boost.
This level will be good well into the 10's on a properly
set up GN.
*****************************************
Nick Micale
3334 W. Marconi Ave.
Phoenix, AZ 85053
602-866-9908
ArizonaGN@earthlink.net
www.ArizonaGN.com
----- Original Message -----
From: "Carl Ijames"
To:
Sent: Saturday, July 12, 2003 8:02 PM
Subject: Re: Engine Mechanicals: NEWER GUY .........3.8 vs 4.1 question
> .060" over 4.1 is 259.6 cu. in. or 4.25 L
>
> As for advantage, the 4.1 gives more displacement, as others have noted.
> However, many believe that the 4.1 block is not as strong as the 3.8 block
Mike I'm just curious as to why you ask, it may help get you the answer you're looking for. I couldn't find any other messages from you to see what your build up is, just going by the "newer guy" part I would guess that you are curious to see if you should go straight to the bigger motor for more power? I'll be honest, I don't have any experience with a 4.1 but I know quite a few guys running the 3.8 that are going very fast so I wouldn't think you'd need to spend the extra time and money trying to build a 4.1.
Anybody know where the magical line is that most would say you need to switch to a 4.1L? What is the standard progression of motors? eg stock 3.8 to low 11s, built 3.8 with girdle to low 10s, StageII? 4.1L?
>Mike I'm just curious as to why you ask, it may >help get you the answer you're looking for.
While not wanting to appear sacreligious, the immediate builds we're doing are NA. Yesterday we completed a 3.8 with 9.5 to 1 hyp. pistons, DIY head work, cam and bearings. Your board and theTB board are the only place where one can get volumes of first hand info on these engines. If the Turbo Gods see fit, we'll have a Turbo in our future, (or if I hit the lottery, I'll get one of those new TA engines).
Thanks to all who have provided me with such valuable and unique info.