Power mods for the I-5

[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.

[HummBebe]

Very few people would actually "race" with an inline 5.

Rod Hall, maybe.

If you have the shop, tools, talent, ability and machinery to do something you all are desribing, why not just put a 350 in it??

It makes just as much sense

Want in one hand, crap in the other, see which one fills up faster

Leave the I-5 alone. It is what it is.

Different vehicles for different purposes for sure, many of us have fast sports cars in the garage for fast road work.

S.

[ChevyHighPerformance]

Originally Posted by Steve - SanJose

265 hp not likely with aftermarket stuff (excluding turbo, s/c).

S.

I've already seen the before and after dyno plots.

[PARAGON]

Originally Posted by Steve - SanJose

265 hp not likely with aftermarket stuff (excluding turbo, s/c).

S.

So now it's:

Originally Posted by ChevyHighPerformance

I've already seen the before and after dyno plots.

after previously saying a few minutes earlier:

Originally Posted by ChevyHighPerformance

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

[PARAGON]

[ChevyHighPerformance]

Originally Posted by PARAGON

So now it's:


after previously saying a few minutes earlier:

Nothing like a sure bet.

[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

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

Michael

Mikey, I think you are quickly losing some of the information you learned during the school year in your high school shop class.

[PARAGON]

Originally Posted by Michael1

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

Michael

dummy, the new SAE tests have shown to INCREASE stated BHP on many domestic engines.

[ChevyHighPerformance]

Originally Posted by PARAGON

dummy, the new SAE tests have shown to INCREASE stated BHP on many domestic engines.

It depends on the manufacturer. Some rating stayed the same, some went up (some GM) , and some went down (some Toyotas). In fact, GM underrates their engines so that their expected worst engine meets the advertised ratings.

[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

[PARAGON]

Originally Posted by Michael1

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

Come on...... do you even know what HP is? HP IS a measure of torque.

[Michael1]

Originally Posted by PARAGON

Come on...... do you even know what HP is? HP IS a measure of torque.

No, it is not. It is a measure of power.

I bet you are one of these uninformed people who thinks the faster car always has an engine which produces more torque.

Michael