Power mods for the I-5

[HummBebe]

Like I said...GM got 20 more HP. Then they ditched it.....no mas Vortec 3500

No sense in getting the nitty gritty, it's not worth the time.

fini

[f5fstop]

Ah, but GM got the 20+ HP from boring the engine out to a 3700. The engine is capable of obtaining quite a bit more HP with a turbo or SC, but unless GM offers it, it would void the powertrain warranty.
Later engines, or those with the new cylinder head, should be able to take the extra HP, as long as you keep it low, around 270. This is not from any GM official information, but from what I know someone did with this engine.

[HummBebe]

The best and only way to improve the acceleration and mpg is to hook the H3 to the back of an H2, put the H3 in nuetral, and relax. It works great.

Been there, done that, got the t-shirt

[HummBebe]

So if that is all they did, was bore, we will now have 10.5:1, 11:1??

Will they now have to step up in octane rating, or will the computer take care of it?

[marin8703]

Thanks for the replies everyone!

[f5fstop]

Originally Posted by HummBebe

So if that is all they did, was bore, we will now have 10.5:1, 11:1??

Will they now have to step up in octane rating, or will the computer take care of it?

Compression ratio is 10.3:1. so it went up .3 (current has a 10:1). You will not have to burn premium fuel, the computer is programmed to compensate.

[Michael1]

The limiting variable for drivetrain life is torque, not horsepower. Keeping that in mind, the torque drops off from the peak about 20%, so that is your opportunity. You can forget about all those air filters, and exhaust systems. You won't get 20% with those. I'd suggest you look into what people do who race this engine. The first place I would look for more power would be porting the heads, and putting in bigger valves. Then I would be looking at the intake manifold. I would shorten the runners for tuning at a higher RPM, and port it for better airflow. The other place would be the exhaust manifold, and replacing it with tubular headers. This is a touchy area though, because there is a close couple catalytic converter.

Michael

[ChevyHighPerformance]

Originally Posted by Michael1

You can forget about all those air filters, and exhaust systems. You won't get 20% with those.

Michael

I bet you can get to 265 BHP with the correct air box/intake, exhaust, and tuning.

265 hp not likely with aftermarket stuff (excluding turbo, s/c). GM did it the right way to the I5 in 2007, and the power increase is modest.

All Hummers (H1, H2, H3) are slow street machines as usual, because their strength is offroad ability.

S.

[Michael1]

Originally Posted by ChevyHighPerformance

I bet you can get to 265 BHP with the correct air box/intake, exhaust, and tuning.

Over 20%???!!! Not any SAE certified test, with all emission equipment functioning and within spec. Maybe on some bogus inertial dyno.

Michael

[PARAGON]

Originally Posted by Michael1

The limiting variable for drivetrain life is torque, not horsepower.

Actually, that's not really true. Since HP is the measure of torque over time, HP is just as limiting a factor as torque.

You can't have HP without torque.

Now suggesting one to copy what race engine builders do, is not a very good idea either. They get to tear their engines down after relatively few miles and are pushing the engine to the limits during most of it's running life.

You simply are not going to be able to do much with this engine to justify a tear down, port, polish and rebuild just to gain a few HP on the high end.

[Michael1]

Originally Posted by PARAGON

Actually, that's not really true. Since HP is the measure of torque over time, HP is just as limiting a factor as torque.

HP is not the limiting factor, unless you are talking about heat rejection due to internal friction, or a design limit for maximum internal rotating speed.

Most engines do not produce their peak torque at maximum RPM as you are implying here.

Check the manufacturers specifications for drivetrain components. They do not list horsepower. They do list torque.

Michael

[hummer_metal]

Agriv8r told me I was nuts if I posted what I added to my H3 to give it a little more power and increased gas mileage.

I'm not sure about spamming this site.



He kinda chuckled at me and told me about this forum. Now I have only had it a couple days, and not sure if it works as I have had the same tank of gas in.

However, say I am tricking myself to believe that it is working is fair enough. But I believe that I am getting 3 maybe 4 miles more to a gallon. HP, well I am not so sure about this yet.

[hummer_metal]

ebay item number 330004099308

[Wisha Haddan H3]

Originally Posted by hummer_metal

Agriv8r told me I was nuts if I posted what I added to my H3 to give it a little more power and increased gas mileage.

I'm not sure about spamming this site.



He kinda chuckled at me and told me about this forum. Now I have only had it a couple days, and not sure if it works as I have had the same tank of gas in.

However, say I am tricking myself to believe that it is working is fair enough. But I believe that I am getting 3 maybe 4 miles more to a gallon. HP, well I am not so sure about this yet.

Popular Mechanics did some testing and didn't think much of that kind of device. I'm pretty skeptical myself. http://www.popularmechanics.com/auto...tml?page=1&c=y

[PARAGON]

Originally Posted by hummer_metal

Agriv8r told me I was nuts if I posted what I added to my H3 to give it a little more power and increased gas mileage.

I'm not sure about spamming this site.



He kinda chuckled at me and told me about this forum. Now I have only had it a couple days, and not sure if it works as I have had the same tank of gas in.

However, say I am tricking myself to believe that it is working is fair enough. But I believe that I am getting 3 maybe 4 miles more to a gallon. HP, well I am not so sure about this yet.

you would have better chance if you stuck one of this in your H3






Do you use one of these for recoveries?



Cool stuff!

[wpage]

Had some improvement in performance by adding S&B Filter replacing stock air filter. In addition cut a 3" hole and inserted a aluminum flex tube running out under thru front starboard wheelwell to hole in bumper as a natural ram with a common air conditioner filter.
My estimate 5-10% gain in torque and hp. Impact on warrentee after cutting hole in air plenum is unknown!

[PARAGON]

.

[KenP]

Ram Air on a HUMMER?

Yea and engineered by hacksaw. No need to ask the dealer about warranty coverage. More noise than horsepower gain is guaranteed.

S.