V8 H3 Alpha

[MarineHawk]

Originally Posted by PARAGON

It's all a matter of power vs. weight.

Para, that's just what confounds me.

The H2: 325 HP (@5,600 rmp)/6,400 lbs = 1 HP/19.69 lbs

The H3: 242 HP (@5,200 rmp)/4,700 lbs = 1 HP/19.42 lbs

Thus, if these numbers are correct, the H3 is about 1.4% more powerful than the H2 per weight carried. If you add the same equal weight, say 500 lbs, of people and cargo, to each vehicle, this does favor the H2, a little, but the ratio then becomes 1/21.23 for the H2 vs. 1/21.49 for the H3, which is only a 2.1% advantage in power/weight for the H2.

Is the reason the H3 is/seems less powerful because of the higher rpms required of the I5 or something else?

[Xotik H3]

Originally Posted by MarineHawk

Para, that's just what confounds me.

The H2: 325 HP (@5,600 rmp)/6,400 lbs = 1 HP/19.69 lbs

The H3: 242 HP (@5,200 rmp)/4,700 lbs = 1 HP/19.42 lbs

Thus, if these numbers are correct, the H3 is about 1.4% more powerful than the H2 per weight carried. If you add the same equal weight, say 500 lbs, of people and cargo, to each vehicle, this does favor the H2, a little, but the ratio then becomes 1/21.23 for the H2 vs. 1/21.49 for the H3, which is only a 2.1% advantage in power/weight for the H2.

Is the reason the H3 is/seems less powerful because of the higher rpms required of the I5 or something else?

You said a mouthful but you left out the most important factor - Torque. While HP is how quickly you can get "work" done, Torque states how much you can do.

[MarineHawk]

Originally Posted by Xotik H3

You said a mouthful but you left out the most important factor - Torque. While HP is how quickly you can get "work" done, Torque states how much you can do.

I understand, but I thought that the H3 can get the work done, it just takes it more time (i.e. slower acceleration) than some desire.

[JAYB1RD]

Originally Posted by MarineHawk

I understand, but I thought that the H3 can get the work done, it just takes it more time (i.e. slower acceleration) than some desire.

It's because of the difference in torque curves.

The H3 peak torque is at around 4000rpm I believe. My old truck has just 210hp, but is much stronger than the 3.7L H3 off the line because its peak 300ft lbs come in at 1800rpm. Both trucks weigh comparably the same and have 33" tires, but the old chevy 5.7L has much more grunt, at every rpm, even though it only has 3.42 gearing!

Don't get me wrong, I think the H3 power is plenty adequete as it is. It can still get you in some trouble with the law enforcement officers if you want, but you just have to keep the revs over 3000rpm to get them to notice you. That's just the nature of a small inline engine. The I5 makes a great base engine, but an optional V8 with more low-end grunt would go over very well with just about everyone.

[Urban Ops]

Nice to see someone bring up the torque talk. I know from experience, my Dodge Dakota Quad Cab with the 4.7 V8 was a rocket, especially compared to my H3. But when it came to towing, my H3 would out pull my Dakota towing 4,400 lbs of Samurai on a 14 foot trailer up Ice House Road and to Moab getting better mileage at the same time. Torque is where it's at! Sure, I wish my H3 would take off the line like my Dakota did and I really wished it could pass like my Dodge, but it can't. I just got used to it. And for the record, I would trade in and pay more for a V8 option.

[HummBebe]

The H3's peak torque is at 2800RPM.

[JAYB1RD]

http://www.gmhummer.com/timeline/2007/2007h3.htm

Originally Posted by GM Hummer

Vortec 3.7L I-5 inline five cylinder with 242 horsepower (180 kW) at 5600 rpm* and 242 lb ft. of torque (328 Nm) at 4600 rpm*

A number of sites say the 3.7L peaks at 4600rpm. A more thorough search than trying to remember off the top of my head returns the 2800rpm specification as well, but seems to be tied to the 3.5L. And that may be true, as the 3.7L might just build off of that number on it's way to 4600rpm, making for a pretty flat torqe curve. Unlikely though, considering how much harder the engine pulls over 4000rpm. Of course, one website said the HP and torque values were EACH less than 150!! I will have to do some more digging later.

[RubHer Yellow Ducky]

Originally Posted by HummBebe

The H3's peak torque is at 2800RPM.

My QUEEN...

is that for the 3.5, or the 3.7 or the V-8 ???

RYD