IAT vs. HP

[STANMAN]

So, just got back from having cams put in my car, was hoping for 500rwhp, was also hoping for cooler temps. Last time I was out after getting the supershaker installed it was the same type weather, about 95 degrees ambient temperature, IAT on a cold start up was 115 degrees. Not ideal dyno weather either time. When I first had the blower installed (pre supershaker) the car made 470rwhp, in almost ideal conditions. Supershaker upgrade, shitty conditions, dynoed at 440HP, so a 30HP loss due to weather, as the supershaker does not affect HP according to Saleen. This time, with the cams and shitty conditions, 475hp, so a 35HP increase from the cams. I can live with that, although I really wanted to see the magical "500HP" on paper. I guess I will have to live knowing it's really there, just not on paper, lol. It is good to know that under the worse conditions possible it's still making 475.

I guess I was just suprised that IAT's can have THAT huge of an effect. I guess that's why meth kits are so popular!

[BR3W CITY]

Meth is addictive! And thats not really even a double entendre.
When I was interested in getting a speed density tune, this was an issue that came up. When the air temp changes so drastically and the air density changes with it, it can be really hard to get consistent power. Meth kits are pretty cheap (I've even seen home built kits work well), only thing is you have another tank to fill up.

[BAD LS1]

Well the iat from the maf sensor is only half the story and is just heat soak surely. You are probably packing 145 degree + air into the combo chambers after the blower/intercooler. That is one of the down falls of pd blowers is that you will quickly find the limit of what pump 93 can deal with heat wise which is a limiting factor on timing. Timing advance is what makes the torque/power. You are in a good safe range for a stock short block. Much over 500 and the turn rods into question marks. But to answer the main question, it's not unusual to see a big drop in power on hot soupy days with real high dew points. The Dyno should spit out weather corrected (sae j1349 spec) numbers as well as the actual raw numbers. The sae numbers are what it would make in better, but not perfect weather.

[EvolvedRegal]

I had a few mishaps from running meth. E85 is the way to go.

[STANMAN]

Well the iat from the maf sensor is only half the story and is just heat soak surely. You are probably packing 145 degree + air into the combo chambers after the blower/intercooler. That is one of the down falls of pd blowers is that you will quickly find the limit of what pump 93 can deal with heat wise which is a limiting factor on timing. Timing advance is what makes the torque/power. You are in a good safe range for a stock short block. Much over 500 and the turn rods into question marks. But to answer the main question, it's not unusual to see a big drop in power on hot soupy days with real high dew points. The Dyno should spit out weather corrected (sae j1349 spec) numbers as well as the actual raw numbers. The sae numbers are what it would make in better, but not perfect weather.

Yeah, I just wanted the real numbers to report, he asked if I wanted the "corrected" numbers, which I didn't. It made what it made, not "shoulda woulda coulda". But I choulda made 500, lol.

[WhatsADSM]

Yeah, I just wanted the real numbers to report, he asked if I wanted the "corrected" numbers, which I didn't. It made what it made, not "shoulda woulda coulda". But I choulda made 500, lol.

Everyone should quote SAE corrected numbers. You should always ask the dyno operator for SAE corrected numbers.

If you just took whatever he gave you... well then I dunno. He could give you raw numbers which on a warm day would read low, or he could have given you STD numbers in which case they would be reading high and it made even less.

[Dr.Buick]

Need a paper that says 500 rwhp. How many you want. I have a stack full just a number.

[Prince Valiant]

For me it is always interesting as a pilot flying on "Hot and high" day vs. that of a cold day...

Understand, not only does the heat/temp/humidity/pressure affect the meager power the engines I fly make (110hp typically), but it affects how my prop moves the air, how the wings generate lift, etc....so MANY performance factors vary greatly due to conditions.

On a cold day the little skipper feels like it's jumping off the pavement in around 200-250ft (even if the performance charts call for 700-800ish) as loaded. Same load though on a 90 degree, high humidity, low pressure day and it feels like I use over half the runway (~2500ft). HUGE difference in the acceleration since in both cases, you're "rotating" (picking the nose up) at the same speed regardless. It's dramatic.

[CATNHAT]

Still pretty good number. I would take it.

[STANMAN]

Everyone should quote SAE corrected numbers. You should always ask the dyno operator for SAE corrected numbers.

If you just took whatever he gave you... well then I dunno. He could give you raw numbers which on a warm day would read low, or he could have given you STD numbers in which case they would be reading high and it made even less.


They are corrected, just a matter of how "corrected" you want them. There are several different specs of "corrected" numbers, like Tom pointed out.

[STANMAN]

Need a paper that says 500 rwhp. How many you want. I have a stack full just a number.

This is true, it's just a number!

[xxtremeteam]

Bob quit throwing money at that car and buy mine

[STANMAN]

I had to get the clutch replaced, cams weren't that much as long as I was out there.