Well that is some darn good cranking compression and because of it you're getting some healthy torque readings. Cam must be installed in the sweet spot.
What a cool document! I am impressed with how many of the various parameters they had the ability to measure back then. There is a ton of information in there.
Dyno, just for the sake of argument the way you're talking then there must be a lot of shops that don't use their dynos much and turn work away if the weather conditions just aren't right. Or if you live in the Rockies or in the desert or way up north. You said it yourself there rarely is a perfect day. I'm not talking about the Mom and Pop dyno shops... I said RACE SHOPS. When we dyno for the NASCAR guys, and they are looking for 2 h.p. then every variable counts. ou:
Your last post confused me until I realized your first paragraph was quoting Mike's comment. To make this sort of thing easier to read, just hit the "quote" button and edit the text as needed, rather than "reply". :beer Devon
I gave up on dreaming about dyno tunes and Hp figures the day I first drove my car. I know it only made 170hp at the crank (stock 72 2bbl 350 at the time) But HP means nothing without a timeslip to back it up anyways. The only time I'll use HP and TQ figures is to see what changes certain upgrades give me and maybe just to aide in calculations for anticipated ETs
Dyno, I absolutely hear ya on what a race team will go through for an edge. Maybe it is just my comprehension but, while I believe you were trying to teach something about dyno testing, when you look at the above quotes as a whole it appears to discount 61Caddy's dyno results and caused him to be confused especially when you read his response. My point was the correction factor is a valid way of quantifing the dyno's results and isn't some sort of cheating(unless somebody has their thumb on the scale).
Devon, that is some great reading. I have to make a copy of that report for the files. I hope the GM secret police don't come looking for me.
I agree, I may have confused him. The problem is comparing your results to someone elses.... Different dyno, different day... Results will vary. Correction factors are good... just have to make sure everyone is using the same multiplier...
I'd be stoked with that kinda power TO THE REAR WHEELS! Especially for a mild motor. Remember, those are rolling dyno numbers, not flywheel. BIG difference. If it was on a engine dyno, i'd bet you'd have another 25hp! :3gears:
STILL suspicious Define "real number". I wish I understood this better. WHICH "SAE" spec are they correcting to? There's three that I'm aware of--SAE gross (pre-'72), SAE net ('72--about 2008 or so) and the most recent SAE net spec, which was adopted fairly recently. As I understand it, SAE gross allowed for cold air into the carburetor, and dyno-setting the ignition timing for best output. The SAE net for '72 mandated higher intake air temperature to more closely follow what the engine would "see" as installed in a typical car; and required ignition timing to be set to the published spec. As a result of these and other changes, the rated horsepower was considerably reduced--and rightly so. The most recent SAE specs made changes that are unclear to me--haven't found out much about them; but some engines tended to add a percent or three to the published horsepower figures, and others lost a percent or three. There is then the difference between horsepower rated at the flywheel, and rated at the rear wheels. 271 horsepower at the wheels seems optimistic to me, but then I've been accused of being "the most negative fricken troll ever" on another forum.
Schurkey, the specs you are talking about are for engine dynos and the engine loaded with/without accessories for car manufacturers and may/may not be out of date. I'm sure the standards have changed since '72. It has nothing to do with what was going on here. The chassis dyno used the SAE correction factor that Dynotech1 mentioned above for weather conditions only. I imagine it is the latest standard, but don't quote me on that. One thing you can be sure of when all the accessories, transmission and rearend are accounted for the RWHP will go down compared to the flywheel HP. You can see the correction factor used for 61Caddy's runs at the bottom of the sheet at the end of all the weather conditions for each run. For the 272 HP run the actual temp was 92.59, 29.04 pressure, and 24% humidity. Dynotech 1 doesn't mention what the spec is for humidity but you can clearly see the pressure was lower and temp was way higher for the run. What ever HP was made that run was multiplied by the SAE CF to come up with what the engine would be putting out if the actual weather conditions were exactly like the SAE spec. In this case, going in reverse, it would be 272 1.04 = 261.5 HP at the wheels. That is what the car would have if there was a dragstrip outside the door at that moment but if the temp suddenly went down to 77 and the pressure went up to 29.23 then he would have 272 HP at the wheels theoretically and would run accordingly faster. If they used the STD correction factor Dynotech1 mentioned the RWHP would have been even higher when corrected. You might use the STD CF if you wanted some feel good dyno numbers compared to the SAE.
Good point on the humidity. we keep it between 45-55 grains/lb I didn't clarify what STD factor is... STD is what is used for most magazine, and Race Shops. STD Is about 4 % above SAE J1349. J1349 is the Auto industry standard (Society of Automtive Engineers).
I did not look @ this page at all! looking @ the baro (29.04) Humidity (24%) and Inlet air temp (92.59) I can see why the correction factor is high... If using SAE factor 77inlet air, 29.23 baro, and 45grains/lb it will correct up due to the delta between inair temp, and baro.
http://www.sae.org/certifiedpower/brochure.pdf The actual procedure and specifications are "only" $65: http://standards.sae.org/j2723_200708/ But especially: http://www.land-and-sea.com/dyno-tech-talk/corrected-horsepower.htm Add 15% to the measured power, then multiply by the "correction factor" before subtracting the 15% again. Seems inflated to me, but I thought the numbers seemed inflated back in post #6. What the hell do I know?
ya sounds like a marketing scam. know a guy with a newer gto had about 12k done to the motor no specifics. dyno said over 600 horse. and it wont run into the 11s with good traction. shop said low 10s. another friend spent 5k on a 01 ta ls1. made like 100horse more than stock and ran a 13.8 to his stock lt1s 13.6 with drag radials.. dyno is tuning tool if you ask me not something that will give you an et estimation.
