New at this, trying to understand horse power

I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
cylinder that delivers 280 hp and about the same mileage as my jeep.

How is the Infinity getting so much more HP and the same gas mileage with
smaller displacement?

We're talking 40% more HP.

Is it better Technology or Engineering or both?

Or is Infinity less than truthful about thier HP rating?

Thanks

Wow! Now there's a good question! Talk about opening a can of worms.
There is so much going on in a motor that is design adjustable that it
cannot be explained too easily in one post. As far as motor design,
Straight six, V6, cam degrees, stroke, piston number, piston size,
timing, aspiration, fuel delivery system, etc. etc., all can be altered
for vastly different results. Gearing is also a factor in gas mileage.
The two motors you are comparing are apples to oranges as far as design
and each is designed for a niche purpose. Where the Jeep is designed for
more low end torque, the Nissan is designed for smoothness and more HP
through a higher RPM range. It all comes down to a small explosion in
each cylinder and how the surrounding metal is moved by that explosion.
I suggest searching and reading up a bit, then come back with some more
specific questions or you may max out the Usenet with opinions and flame
wars.

Brian Foster wrote:
> I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
> cylinder that delivers 280 hp and about the same mileage as my jeep.
>
> How is the Infinity getting so much more HP and the same gas mileage with
> smaller displacement?
>
> We're talking 40% more HP.
>
> Is it better Technology or Engineering or both?
>
> Or is Infinity less than truthful about thier HP rating?
>
> Thanks


--
__________________________________________________ _________
tw

71 Bill Stroppe Baja Bronco
03 TJ Rubicon - Rubicon Express 4.5"
01 XJ Sport

There is a very fine line between "hobby" and "mental illness."
-- Dave Barry

Pronunciation: 'jEp
Function: noun
Date: 1940

Etymology: from g. p. (G= 'Government' P= '80 inch wheelbase')
A small general-purpose motor vehicle with 80-inch wheelbase,
1/4-ton capacity, and four-wheel drive used by the U.S. army in
World War II.

(Please remove the OBVIOUS to reply by email)
__________________________________________________ _________

"Brian Foster" > wrote in message
...
>I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
>cylinder that delivers 280 hp and about the same mileage as my jeep.
>
> How is the Infinity getting so much more HP and the same gas mileage with
> smaller displacement?
>
> We're talking 40% more HP.
>
> Is it better Technology or Engineering or both?
>


Both. The GC uses an ancient design that has been reconfigured numerous
times over 50+ years but does not benefit from overhead cams, 4 valve/cyl
etc. There is a lot more resistance inside the 4.0 than the 3.5. It's unfair
to compare 21st century technology with an engine designed in the early to
mid 1900's.
You can not bring fuel consumption into the arguement because now we are
comparing the GC to the FX... a brick to a bullet. There is added weight and
rolling resistance in the GC... if you had the 3.5 in the GC, the fuel
consumption would probably be almost comparable.

-Brian

From Infinity websight. FX35 with 2wd is 4,110 lbs

from my GC ownersmanual 2wd 4.0liter weight is 3791 lbs

The Infinity is 319 lbs heavier and has a smaller engine and gets same gas
milage with 80 more HP.


"Cherokee-Ltd" > wrote in message
...
>
> "Brian Foster" > wrote in message
> ...
>>I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
>>cylinder that delivers 280 hp and about the same mileage as my jeep.
>>
>> How is the Infinity getting so much more HP and the same gas mileage with
>> smaller displacement?
>>
>> We're talking 40% more HP.
>>
>> Is it better Technology or Engineering or both?
>>
>
>
> Both. The GC uses an ancient design that has been reconfigured numerous
> times over 50+ years but does not benefit from overhead cams, 4 valve/cyl
> etc. There is a lot more resistance inside the 4.0 than the 3.5. It's
> unfair to compare 21st century technology with an engine designed in the
> early to mid 1900's.
> You can not bring fuel consumption into the arguement because now we are
> comparing the GC to the FX... a brick to a bullet. There is added weight
> and rolling resistance in the GC... if you had the 3.5 in the GC, the fuel
> consumption would probably be almost comparable.
>
> -Brian
>

Depends on what you want from your engine really.
The only figures I can find for the infinity engine is VQ35 DOHC 24-valve
3.5L V-6 - 260 hp at 6,000 rpm and 260 lbs-ft of torque at 4,800 rpm. The
Jeep 4.0 puts out 190hp and 220 lb/ft at 4000rpm, but 85% of that torque is
available at 1500 rpm. I'd be interested to see the infinity torque number
at 1500.

Dave Milne, Scotland
'91 Grand Wagoneer, '99 TJ
"Cherokee-Ltd" > wrote in message
...
>
> "Brian Foster" > wrote in message
> ...
> >I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
> >cylinder that delivers 280 hp and about the same mileage as my jeep.
> >
> > How is the Infinity getting so much more HP and the same gas mileage
with
> > smaller displacement?
> >
> > We're talking 40% more HP.
> >
> > Is it better Technology or Engineering or both?

OT: I second that depends on what you want ... I like the fact that my old
4.0 idles along at about 100km/hr at about 1800 rpm very comfortably pulling
my 3000 lb boat ... and doing it burning regular gas :-)

"Dave Milne" > wrote in message
k...
> Depends on what you want from your engine really.
> The only figures I can find for the infinity engine is VQ35 DOHC 24-valve
> 3.5L V-6 - 260 hp at 6,000 rpm and 260 lbs-ft of torque at 4,800 rpm. The
> Jeep 4.0 puts out 190hp and 220 lb/ft at 4000rpm, but 85% of that torque
is
> available at 1500 rpm. I'd be interested to see the infinity torque number
> at 1500.
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
> "Cherokee-Ltd" > wrote in message
> ...
> >
> > "Brian Foster" > wrote in message
> > ...
> > >I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter
6
> > >cylinder that delivers 280 hp and about the same mileage as my jeep.
> > >
> > > How is the Infinity getting so much more HP and the same gas mileage
> with
> > > smaller displacement?
> > >
> > > We're talking 40% more HP.
> > >
> > > Is it better Technology or Engineering or both?
>
>

Hi Brian,
Put a rev kit in it: http://www.crower.com/ Then blow it:
http://members.cox.net/wilsond/zj.html Of course it'll rock crawl about
as good as your POS Japanese rice burner.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

Brian Foster wrote:
>
> I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
> cylinder that delivers 280 hp and about the same mileage as my jeep.
>
> How is the Infinity getting so much more HP and the same gas mileage with
> smaller displacement?
>
> We're talking 40% more HP.
>
> Is it better Technology or Engineering or both?
>
> Or is Infinity less than truthful about thier HP rating?
>
> Thanks

There are oodles of factors involved that determine horsepower. Without
going into depth, here are a few things to consider:

A Honda Accord has 220some HP. This just means it has a lot of take-off
power and can probably pull a fair-sized load. However, this car is designed
for higher RPM and smooth operation. For the sake of explanation, add a 6"
lift and put some 33" tires on the Accord and try and go through a mud hole.
The car has little low-end torque and a completely wrong set of gears. So,
given that the GC (about 190HP?) and Accord have comparable HP ratings, they
are designed to do completely different things.

Next up, consider gas mileage. I'm using the Accord VS GC example again
because it is more black VS white. The car is aerodynamic whereas your GC is
like driving a barn through a headwind. The car is designed for high-RPM
shifting, quick power transfer to the wheels for a fast take-off, and a
smooth, light ride. The GC is designed to pull my house off the foundation,
tear the pavement to shreds upon take-off, and is unsmooth (good word, eh?)
enough to burp a child. Similar HP but completely different purpose. Also on
the topic of gas mileage, consider the engine design. The GC engine is based
on an old design which is less concerned with conservation of fuel and more
concerned with "gimme lotsa power right-bloody-now and turn it into low-end
torque!!" The Accord engine is based on "must be able to post 35mpg on the
sticker to sell the car quickly" and only delivers the extra fuel when you
stomp on the gas. Not to mention, (awaits argument from Bill), those Jap
engines are extremely efficient when it comes to injection.

Third thing, consider my poor 4cyl rust-bucket, driven-to-hell-and-back '85
CJ7. I doubt that thing has any more than about 60HP now-a-days but when my
buddy's '91 YJ was up to the fenders in mud, I had absolutely no problem
pulling him out. For comparison-sake, I'd challenge any Infinity driver out
there to a 30 foot long X 1 foot deep mud bog and despite having 200HP, 2
extra cylinders, and an extra litre of displacement, I would still put my $
on my old CJ. Why? Cuz my little baby is designed to turn that 60HP into
"plow-power" and the Infinity is designed to carry Mrs.Anderson and her 4
kids to the grocery store.

As for technical info ...best bet is to just look it up on google. A lot of
high performance sites will have lengthy technical data, comparisons, and
diagrams. As a quick answer to your question though, I wouldn't call it
"better" engineering or technology. It *is* newer and more efficient ...but
it's just a "different" design for a different purpose. I can't say I know a
person who bought a Jeep because they wanted good MPG. I'm usually happy
with anything over 8mpg ;p One day I'm gonna do the engine/tranny/EFi swap.
One day.

"Brian Foster" > wrote in message
...
> I have a 4.0 liter 6 cylinder in my GC. The Infinity FX35 has 3.5 liter 6
> cylinder that delivers 280 hp and about the same mileage as my jeep.
>
> How is the Infinity getting so much more HP and the same gas mileage with
> smaller displacement?
>
> We're talking 40% more HP.
>
> Is it better Technology or Engineering or both?
>
> Or is Infinity less than truthful about thier HP rating?
>
> Thanks
>
>

----- Original Message -----
From: "Brian Foster" >
Newsgroups: rec.autos.makers.jeep+willys
Sent: Sunday, January 02, 2005 12:29 PM
Subject: New at this, trying to understand horse power


> From Infinity websight. FX35 with 2wd is 4,110 lbs
>
> from my GC ownersmanual 2wd 4.0liter weight is 3791 lbs
>
> The Infinity is 319 lbs heavier and has a smaller engine and gets same gas
> milage with 80 more HP.
>

First off, I thought you were talking about the glorified Nissan Maxima - I
don't know the Infinity line up that well.
Getting back to the question, you can't expect a prehistoric pushrod engine
to perform anywhere near that of a high compression DOHC 24 valve engine.

The 3.5 utilizes modern age technology to take advantage of;

Volumetric efficiancy - high flow tuned induction, polished intake, 4 valve
configuration, DOHC, electronic variable valve timing etc.
Thermal efficiancy - aluminum block, intake and heads, high compression etc.

Is it any wonder why the IRL used them? Mass produced, affordable race
engines. You won't see too many 4.0's racing except of course for JeepSpeed
where they need cast iron to keep the front end on the ground!
http://jeepspeed.com/images/2a.jpg

-Brian

Thanks for the insight. So the infinity uses "newer" technology if I
understand you right?

The other responses almost all dealt with low RPM tourque in the old
fashioned Jeep Engine VS the newer design infinity power plant. The lower
end tourque is preferable with a Jeep type vehicle than the additional HP at
higher RPM?

Perhaps another stupid question, but couldn't gearing (transmission) take
advantage of the higher HP at higher RPM without sacrificing tourque?

BTW did I notice that the 05 GC has a different engine with less
displacement than before? Something like 3.5 or 3.7 to the old 4.0.

I like my Jeep but I also like the looks (and specs) on the Infinity FX. I
don't do any offroading with my jeep. The Infinity looks like a brute road
handling machine. 20 inch tires and 280 hp is pretty impressive. The
pricetag is in the mid to high 30s and you can buy a lot of Jeep (or a Jeep
& a boat) for that kinda $$.


"Cherokee-Ltd" > wrote in message
...
>
> ----- Original Message -----
> From: "Brian Foster" >
> Newsgroups: rec.autos.makers.jeep+willys
> Sent: Sunday, January 02, 2005 12:29 PM
> Subject: New at this, trying to understand horse power
>
>
>> From Infinity websight. FX35 with 2wd is 4,110 lbs
>>
>> from my GC ownersmanual 2wd 4.0liter weight is 3791 lbs
>>
>> The Infinity is 319 lbs heavier and has a smaller engine and gets same
>> gas milage with 80 more HP.
>>
>
> First off, I thought you were talking about the glorified Nissan Maxima -
> I
> don't know the Infinity line up that well.
> Getting back to the question, you can't expect a prehistoric pushrod
> engine
> to perform anywhere near that of a high compression DOHC 24 valve engine.
>
> The 3.5 utilizes modern age technology to take advantage of;
>
> Volumetric efficiancy - high flow tuned induction, polished intake, 4
> valve
> configuration, DOHC, electronic variable valve timing etc.
> Thermal efficiancy - aluminum block, intake and heads, high compression
> etc.
>
> Is it any wonder why the IRL used them? Mass produced, affordable race
> engines. You won't see too many 4.0's racing except of course for
> JeepSpeed
> where they need cast iron to keep the front end on the ground!
> http://jeepspeed.com/images/2a.jpg
>
> -Brian
>
>