Power mods for the I-5

[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]

. Someday I'll get to drive one too.

S.

[ChevyHighPerformance]

Just as an example, here is someone else's dyno plot from another website for an H3 with an airbox, exhaust, and tuning. This after these mods the BHP is about 253 hp. From what I was told, this is without port matching of the CAI, stock throttle body, no thermal shields, and no cold air ducting. Also, this might have been with the stock resonator.

[PARAGON]

Originally Posted by ChevyHighPerformance

Just as an example, here is someone else's dyno plot from another website for an H3 with an airbox, exhaust, and tuning. This after these mods the BHP is about 253 hp. From what I was told, this is without port matching of the CAI, stock throttle body, no thermal shields, and no cold air ducting. Also, this might have been with the stock resonator.

so, the extra 100HP is arbitrary?

What I see is a 12-13 point increase in HP which is less than a 10% increase at the rear wheels even.

[HummBebe]

100 pts both HP and Torque, yes?

It reads 153 not 253? I'm confused

[ChevyHighPerformance]

Originally Posted by PARAGON

so, the extra 100HP is arbitrary?

What I see is a 12-13 point increase in HP which is less than a 10% increase at the rear wheels even.

I see about 3.5 block increase for which each block is 5 hp about a 17 - 18 HP gain at the wheels. This is the power measured at the wheels. The drivetrain has an efficiency. The power loss is mostly converted to heat and absorbed in inertial loads. The drivetrain loss is dependent on the drivetrain loading. On a dynojet, the stock peak power might be 165 hp at the wheels.

[f5fstop]

Originally Posted by ChevyHighPerformance

Just as an example, here is someone else's dyno plot from another website for an H3 with an airbox, exhaust, and tuning. This after these mods the BHP is about 253 hp. From what I was told, this is without port matching of the CAI, stock throttle body, no thermal shields, and no cold air ducting. Also, this might have been with the stock resonator.

Hope that is not from the southwest and some "GM engineer." Just a note, I can take any dyno graph and change it the way I like it. Not saying this is what happened, but, if GM could raise the HP (safely) with a tune, and a new cat back system and airbox, they would have already done it. I say safely, but I also mean legally.

[PARAGON]

Originally Posted by f5fstop

Hope that is not from the southwest and some "GM engineer." Just a note, I can take any dyno graph and change it the way I like it. Not saying this is what happened, but, if GM could raise the HP (safely) with a tune, and a new cat back system and airbox, they would have already done it. I say safely, but I also mean legally.

I don't think it was raised by that much.

There is no 100HP difference between BHP and rear wheel HP, which is what is being shown. Stock listed BHP for the H3 is what? somewhere around 220BHP and the stock rear wheel HP listed on the graph is about 138 HP. The coefficient for friction doesn't increase as the HP increases so one could naturally assume a 80HP difference. 153 + 80 = 233 or a net gain of about 13 BHP or somewhere around a 6% gain.

[PARAGON]

I'll give you a 20 BHP gain and it's still less than 10%. Driveline has nothing to do with this since you are looking at the actual before/after.

Again, whatever driveline loss occurs at the stock level will occur at the higher level, you don't arbitrarily just throw in some additional ponies.

[ChevyHighPerformance]

Originally Posted by f5fstop

Hope that is not from the southwest and some "GM engineer." Just a note, I can take any dyno graph and change it the way I like it. Not saying this is what happened, but, if GM could raise the HP (safely) with a tune, and a new cat back system and airbox, they would have already done it. I say safely, but I also mean legally.

This is not my dyno graph. This is from another post from another H3 forum. I was just providing it as an example. You can look in Colordao/Canyon forums for other dynos. Here is a dyno on a dynojet by K&N for an H3. In stock form the drivetrain efficiency (on this inertial dyno) was 75% or 25% loss (0.25 * 220 HP = 55 hp loss)

http://www.kandn.com/dynocharts/77-3044.pdf

I'm not surprised by the 65% drivetrain efficiency with dyno that properly loads down a 4WD vehicle like a Mustang dyno. Here is another dyno from K&N for a colorado same 3.5 L engine but 2WD and the stock HP is 180 hp (compare to 165 hp for the H3).

http://www.kandn.com/dynocharts/63-1095.pdf

The difference peak HP is due to the drivetrain efficiency ~82% for the 2WD colorado and 75% for the H3 on an inertial dyno.

GM has to tune for the masses. Because of production tolerances, different environments, different local fuel, etc. GM can't tune to the performance edge. GM uses a consevative ~11.9:1 A/F at WOT when most tuners bump that to 12.8:1 or so for more power.

GM has noise goals to meet. In the past, GM would ship a Z28 to SLP to have and intake, exhaust, etc. put on and SLP would not have to meet the noise requirements that GM had to meet. A new H3 airbox that eliminates the resonator will have more noise as well as a free flowing exhaust. For the new Z06, GM designed a cutout, so when you went to WOT (which does not have noise requirements) the cutouts opened for more power and substanially more noise.

[Michael1]

Originally Posted by ChevyHighPerformance

For the new Z06, GM designed a cutout, so when you went to WOT (which does not have noise requirements) the cutouts opened for more power and substanially more noise.

Unless the noise standards have changed recently, auto manufacturers still have to meet a 50' full throttle noise test. The cutout is just to make the interior noise level liveable while cruising.

Michael

[ChevyHighPerformance]

Originally Posted by PARAGON

So now it's:


after previously saying a few minutes earlier:

Nothing like a sure bet.

[PARAGON]

Originally Posted by ChevyHighPerformance

Nothing like a sure bet.

RIIIIGGGHHT!