The only low hanging fruit (horsepower) will come from CAI, full exhaust and a tune. Anything over the top of that is going to cost you far more dollars per hp. Next cheapest chunk of power would come from nitrous, a safe nitrous wet kit would cost ya $8-900 and return 50-100hp depending on the size of your *****.

 

Isn't the G37 rated at 330 HP ... 345Hp would be a 15hp gain no?
IIRC R2C and Stillen CAIs have posted 15-18hp dyno gains at the wheels, no?

 

Those dyno results are referencing WHEEL hp. The G37 brochure specs you're referencing are CRANK hp unfortunately. Factory wheel horsepower tends to be well under 300.

 

Ah I must have misunderstood I thought I saw flywheel HP and assumed that was the same as crank HP.
345 at the wheels is a solid gain.

 

Crank and flywheel are different actual physical parts but for HP rating reasons people say either one. BHP, crank and flywheel all mean the HP rating at the flywheel is xxx before you start to measure driveline loss etc..

 

SAE horsepower rules currently require measurement at the transmission tail shaft with all engine accessories installed and operating.

In the good old days, SAE HP was indeed taken at the crank shaft end and minimal ancillary equipment was installed, often not even the engine-driven fuel pump. Since engine dynos were usually water brake devices, that's where the term brake horsepower arose.

Automakers were out to win the HP war in their adverts, not necessarily on the street...until insurance companies stuck their noses into the mix. In addition, infuential people thought it was wrong to measure engine power this way since the car off the showroom had all the stuff tacked on and operating. SAE agreed and changed the measurement standard to what we have today. The older numbers were called SAE Gross HP. Today's HP numbers are SAE Net HP. I believe most manufacturer use eddy-current dynos like the rollers do.

Because we have become more affluent and have the internet to spread bragging rights, folks want to measure the power their car actually makes instead of reliance upon vendor claims, yet that affluence can't swallow pulling engines and transmissions to allow dyno testing, so eddy-current rolling dynos became significant players in the game. Since engine power has to meet the road at the tire, it's considered the best way to measure actual power available to propel the vehicle. It accommodates all drive train and accessory losses. As long as you use the same dyno to measure equipment changes, you know your real power gains or losses.

With many years of empirical data behind it, there is a formula for calculating HP from 1/4-mile time and trap speed. This, of course, will be power at the tire and should closely match a rolling dyno result.

 

Yeah, yeah, blah-blah... Just tell me how to beat the M5 that blew my doors off.


Jk
Thanks that's great info.
It's the wheel hp I'm interested in. Seems to make the most sense. Then again I don't yet have a baseline other than the MFGR crank-hp claims.
Maybe I'll dyno my (mostly)stock G before adding a CAI
If I find a dyno in the NY/NJ/CT area and it's not too pricey.

 

Do it! Just make sure you use the same dyno for now on and you'll get accurate readings for your mods.

 

Manufacturer gives SAE Net, measured at the transmission tailshaft. Hardcore engine builders still use water brake dynos and give you crank HP.