Dyno results in 105*F , 80% humdity and 3400 DA! I just got my '71 Firebird dyno tuned last night, it has a LSA out of a 2013 CTS-V with 2.55 upper pulley and LS9 camshaft, and LT headers (1 7/8) and of course a cold air intake. The weather was HOT!, it was 105F with no less than 80% humidity, the DA was 3400+. The IAT2 temp was through the roof at about 170F. The results were low numbers as expected : 573hp@6200 / 604 ft/lbs@4000sh (not sure). The same engine setup was dynoed last winter in 50F day and it put down 623hp. Does the hot weather and high IAT temps affect the power that much? I mean I expected less numbers but 50hp is a big difference!, will I get back the lost horsepower in a cold day and lower IAT or do I need to re-tune it again in winter? Please share your opinions. |
The dyno operator should be able to report corrected numbers so there is less of a difference due to ambient conditions. |
MAF or SD? |
Originally Posted by G Atsma
(Post 19975688)
MAF or SD? |
The timing is probably reduced via the iat table(ability to add or remove timing based on iats... I can easily see 50rwhp drop if it’s pulling 8-10 degrees... especially if iat’s Are 170+. it really depends on what that table looks like. |
See it at the strip all the time...….50hp seems like a lot, but this DA 3400 Vs something close to 0, I could see it. |
Pictures of car? Sounds like a great build |
Originally Posted by AINT SKEERED
(Post 19976125)
Pictures of car? Sounds like a great build The car was an all original 1971 Firebird Formula 350 with stock engine and TH350 trans. Now it has a LSA with a magnum T56 and a FAB9 9 in rear end. I will get it soon out to the drag strip, I hope I can get it into low 10s. https://cimg2.ibsrv.net/gimg/ls1tech...a7340f5fe2.png https://cimg5.ibsrv.net/gimg/ls1tech...f53f3bdfd3.png https://cimg8.ibsrv.net/gimg/ls1tech...bb79e5e4ee.png https://cimg4.ibsrv.net/gimg/ls1tech...d4aac85e6b.png |
Beautiful car |
That's a very beautiful car. Don't discount the impact of humidity also. I've seen a car in dry air go to humid air and at the same map readings, temperatures, dynamic airflows, etc, the fuel trims and WB error went negative, indicating it was getting less oxygen and cutting fuel. It was around 3% average difference due to humidity. At 680 HP, that's 20 HP approx. |
The dyno should be correcting for the temp and humidity. Both sae and std correction factors will compensate for the air. The iat's being 170 are probably what is causing a power loss. I have tuned dozens of lsa's and ls9's. At 170 iat on 93 octane you need to be pulling 7-8 degrees from the base timing table through the iat table. That's easily 50 whp and then some vs. 100-120 iat. |
Sweet car, very nice numbers. More Tq then HP huh? Interesting. |
1*F cooler is usually 1 hp gain above 100*F |
I...want...one Nice car! |
Do they make a phenolic spacer for the LSA blower? if so, that might drop you air intake charge and get more hp. |
Originally Posted by wannafbody
(Post 19987002)
Do they make a phenolic spacer for the LSA blower? if so, that might drop you air intake charge and get more hp. |
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