Matt let my secret out. I had Jason @ TSP print me off an extra dyno sheet (mine IS sae). The altitude and weather/air conditions here are not the same as the rest of the country and std is very close to sae for most of the year. The air is usually adverse enough that many of us won't race at any local tracks in N/A form.
I'll post the other graph when I get home on wednesday, but we're talking about less than 5hp and 5 ft-lbs of difference.
More importantly, let's talk about pushrods. The optimal setup for my engine turned out to be 7.500" for the intake lobes and 7.450" for the exhaust lobes. I am using Yella Terra non-adjustable rocker arms. Let this be advice to those running a comparable setup.
Cool, interesting to know that math shows it should be around 2.5% on every dyno SAE to STD no matter the location but on yours its around 1%.
Quote:
Originally Posted by -Joseph-
Matt let my secret out. I had Jason @ TSP print me off an extra dyno sheet (mine IS sae). The altitude and weather/air conditions here are not the same as the rest of the country and std is very close to sae for most of the year. The air is usually adverse enough that many of us won't race at any local tracks in N/A form.
Like Joseph said, it is not a flat 2.5% across the board all across the country. it depends on the air. I saw one that SAE vs STD was 11rwhp, once. It also made close to double the hp that Nick's car is.
__________________
Largest Stocking Distributor of LS-x Engines / Largest LS-x Comp Cams Distributor in the Country!
COMP - FAST - PACESETTER - DIAMOND RACING - CALLIES - COMETIC GASKETS - MONSTER CLUTCHES - MOSER ENGINEERING - KOOKS HEADERS - ARP - GM BOLTS AND GASKETS - MSD - NGK - POWERBOND - ASP - AND MORE!
Took the car out to the dragstrip yesterday, the new heads were good for a 6-7mph increase in 1/4 mile trap speeds, which seems consistent with about a 50hp increase from the bone stock heads on there before. Track that I raced at was 4200 ft above sea-level, DA was probably in the 5000ft ball park.
Don't worry to much about Jessica (aka Brett B) or any of his followers. 6-7mph is a kick butt increase my friend.
Hard to argue with a huge mph gain like that, but I'm sure someone will find a way! LOL
I see you guys cleaned up again from the technical info. 6-7mph is a big gain I will agree with that.
What I don't agree with is your boys trying to tell everyone that your weather negates the FIXED 2.6% STD gains over SAE. It would be different if those values varied from atmospheric conditions but the fact is they don't. With that said something has to be going on with your dyno correction values, Im not saying your numbers are wrong/inflated/BS etc but a 2rwhp figure from SAE to STD is just not accurate. Im trying to be as respectful to you guys as possible.
Location: Denver International Airport, Colorado USA
Posts: 386
Hey guys just a little comment concerning the STD vs SAE 'debate'.
Several years ago I had Heads and Cam installed at Texas Speed in Lubbock, TX., followed by several dyno/tunes runs. Likewise is was formatted in STD.
Out of scientific curiosity I had the dyno repeated the following week up here in the Mile High City (Denver). I requested SAE. My SAE numbers here in Denver were 3.4HP less. While I am a big fan of standardizing dyno readings, I crunched some math to try to understand why STD in Lubbock is usually not that far off from SAE.
The important distinction of STD and SAE has more to do with humidity than anything else. The higher in elevation you go the the less absolute humidity you have (95% of the time). The closer you get to sea level not only is more humidity available, but the effects of humidity on the STD vs SAE calculation become even greater.
You can go through all the formulas to get to that answer, but from my one visit to Texas Speed in Lubbock, not only did I replicate the validity of the dyno run.. but if the climate is dry and your elevation is higher..it really is not that big of a difference.
Hey guys just a little comment concerning the STD vs SAE 'debate'.
Several years ago I had Heads and Cam installed at Texas Speed in Lubbock, TX., followed by several dyno/tunes runs. Likewise is was formatted in STD.
Out of scientific curiosity I had the dyno repeated the following week up here in the Mile High City (Denver). I requested SAE. My SAE numbers here in Denver were 3.4HP less. While I am a big fan of standardizing dyno readings, I crunched some math to try to understand why STD in Lubbock is usually not that far off from SAE.
The important distinction of STD and SAE has more to do with humidity than anything else. The higher in elevation you go the the less absolute humidity you have (95% of the time). The closer you get to sea level not only is more humidity available, but the effects of humidity on the STD vs SAE calculation become even greater.
You can go through all the formulas to get to that answer, but from my one visit to Texas Speed in Lubbock, not only did I replicate the validity of the dyno run.. but if the climate is dry and your elevation is higher..it really is not that big of a difference.
Just though I would share my honest expierience.
Thanks.
..WeathermanShawn..
Thats all good and well but the fact is no matter the weather SAE and STD should correct to same percentage because the figures are fixed. How does it matter if its 90 degrees and 100% humidity or 45 degrees with 20% humidity if SAE is going to correct to 77°F, 0% humidity and a barometric pressure of 29.234 in-Hg and STD to 60°F, 0% humidity and a barometric pressure of 29.92 in-Hg?
How is a fixed percentage exempt because its humid or not humid in Texas?
Location: Denver International Airport, Colorado USA
Posts: 386
Blu1, I absolutely see your point.
SAE and STD will always correct to the same correction percentage with perfectly identical weather conditions. The larger variances in both correction factors begin to show up as you move farther and farther away from their standard temperatures, humidities, and pressure.
I was just pointing out that under some circumstances the differences are not always that great. They both reduce air density to 0% relative humidity.
The HP difference from 59F to 77F is only a difference of ~ 1.9HP. the difference in HP from air density reduced to 29.235" vs 29.92" is ~ .2.6HP. the difference from 0% RH to 100% at 77F is ~ 3.9HP. Make it 100F and 100% RH the difference is ~7.5F. (same percentage STD vs SAE).
I absolutely agree with you it is easier to compare dyno runs that use the same correction factor. I was just pointing out that in this particular circumstance the difference was really only about 2-3 HP.
As a general comment why 29.235 and 77F was chosen as SAE for automobile engines is somewhat questionable. It is not the standard atmosphere that most of the world uses. Every aircraft, every weather calculation uses 29.92 and 59F. Reducing pressure to 29.235 just induces even more error in calculating air density.
Everyone knows tricks can be played on dynos, 1/4 mile times, and gross manipulation of weather readings to exagggerate HP numbers. Just pointing out that in my expierience this was not the case. STD correction is just that..standard. It is a totally legitimate calculation. It actually is a more realistic correction factor for higher altitude stations, as correcting to 29.92" induces less error.
I appreciate the discussion and acknowledge your points and concerns. Whether a dyno facility chooses STD or SAE is totally their perogative. For this patircular dyno run, STD vs SAE was within 1% of each other.
