The story about 15hp was around for a while. There are so many posts related to it that, perhaps, it is well known. I figured it only a couple of days ago.

Max00-01 3.0L 222hp
By increasing the engine size to 3.5L we could expect:
222*3.5/3=259hp
That is exactly what was originally claimed for Max02. Later it was changed to 255hp.

I used to have 97 Altima. At that time,
97 Altima 2.4L 150hp
97 Maxima 3.0L 190hp
using the same rule we could expect for Maxima 150*3.0/2.4= 187.5hp

So, it appears that this oversimplefied rule works. It makes sense: the same technology, the same company... Of course, you should compare apples to apples, turbo or sc cars do not obey this rule.

My question is: How did it happen that newer 3.5L is less effecient (per liter) than the older 3.0L engine???

 

I am by no means a mechanical engineer, but my hunch feeling is that this rule just doesn't work. I don't think HP/volume is a linear relationship, meaning that as one goes up, the other goes up by the same rate for ALL volumes--it's more like the law of diminishing returns! Just my two cents.

I just took the BMW 5 series as an example. The 530i has a 3.0 liter making 225hp. The 540i has a 4.4 liter making 290hp. So, using your rule, the 540i should have expected
225 * 4.4/3 = 330hp
But as we see in reality, it "only" has 290. I don't think it's Nissan issue, I just don't think that the HP/volume ratio is linear.

 

You're right. The bigger a car's displacement gets, the harder it is to maximize HP. Honda's S2000 holds the record for making 240 hp from a measly 2 liters. That's 120 hp/liter. If the Viper, with it's massive V10, were as efficient, it would make 996 hp Yet, it "only" makes 500 hp from it's 8.3 liters.

DW

 

Sorry, your rule does not work in practice.
If you add cam and heads to a standard engine you can up the power by 25% without increasing displacement.

 

Yes, guys you are right, HP/vol isn't linear. Especially, if you put more technology into the engine, the number will go up. Another point is also well taken, the big engines are less relatively effecient.

It is, though, funny for 03 BMW 5:

525i 184hp 2.5L
530i 225hp 3.0L

225* 2.5/3.0=187.5hp
It's kind of close to 184hp in 525i.

I wonder why it is difficult to double the power by doubling the voulume. If, for the sake of argument, you imagine that a car got the second engine identical to the first. (It is impossible, of course.) The power will be 2 times more, right? Two engines provide EXACTLY two times more HP than the one engine alone. Double volume would result in double power. (The weight of the engine(s) will also be double, and, that would be unacceptible.)

Kind of puzzling, don't you think?

 

All other things being equal it would be pretty linear for torque, a little less so for HP, but the manufacturers play with other things like intake volume, cam timing, ecu so it can get pretty far from linear. Incidentally, 350cc turns out to be the optimum cylinder size for HP, this is why all the F1 3.5L engines are V10's - even though that requires odd vee angles etc.

 

Doesn't work the other way either. The new Ferrari Enzo (what would it be like to drive one of THOSE?!?) has a 6.0 engine, and makes 660 HP (or 110 HP / liter). To match it, the Max would have to make 385 HP (and what would THAT be like ).

 

Your theory probably works pretty well, given that you stay within the same manufacturer and the same "family" of engines. But, when comparing different manufacturers, you also have to take into account their different "design practices" (loosely-- Nissan= torque, Honda= hp/liter, etc...) which TOTALLY blows it out of the water.

It'll be interesting to see what is to come for the V-series, and to see if your theory holds true with Nissan again.

 

i bet you, nissan used that rule. luring customers that it is actually underrated. maybe thats why the g35 sedan is 260 hp. just rounded UP, while us 2k2s and 2k3s rounded DOWN. same engine. slightly tuned, which i doubt. but maybe. i dunno. but most of us can figure out that it is NOT linear. twice the volume will not produce twice the power. thats if we are talking about the EXACT SAME parts in the engine, but just doubled in size. bigger the displacement will be less efficient in hp. i think i just repeated what other members had said.

 

You didn't use the same ratio as you did in your 1st post. It should be:
184*3/2.5=220.8hp
If you used the same backwards formula in this post for the Max it would be:
255*3/3.5=217.6hp
Which is still better than most are seeing at the wheels stock on at 02, and more than an 01.
There are to many variables for this to work exhaust, cam, head, ecu...

 

maximaman777, check your PM. Thanks.