When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Why not correct for inlet conditions on a supercharged car?
SAE J1995 (Gross Power) section 1.1 states it applies for ...SI naturally aspirated and pressure charged...
SAE J1349 (Net Power) doesn't restrict the use of it for a forced induction engine.
What is interesting is J1995 limits the correction to 5% and J1349 limits it to 3%.
I assume they use SAE J1995, so that picture is showing SAE 1.05 which maybe the max 5% allowed correction.
I'd say Ricks numbers are high too and the inlet temp of 101F is fishy. 5% off of 487 is 463 which is still good.
Also, these corrections won't account for a change in spark timing due to hot or cold temps so I do agree to an extend that correcting them isn't the best, but within the 5 or 3 % seems reasonable.
The dynojet has a weather station built into it. The same day a stock 04 V dynoed 325 rwhp.
I am running 94 octane which likely gains "around" 20-25 rwhp over a 91 octane tune. The numbers are stout for my mods but add in the octane and a great tuner and yes those are the numbers.
The car has no issues pulling on a stock V2. I do believe that the dyno numbers are accurate. We will see what gains I see from headers next. Even if they werent accurate, I have a good base line for upcoming mods. The car trapped 119.6 mph. The E.T. and 60 foot werent good as I was afraid of breaking the rear end, but the mph makes me believe that the rwhp is accurate given the power and weight of the car. The same day a stock V2 with Corsa trapped 116.x mph.
Maybe I have a good runner or maybe there is something else done to the motor that I am not aware of. I bought the car modded and the prior owner dumped all kinds of $$ into it but was vague on the mods.
Last edited by 88BlackZ-51; 07-21-2016 at 04:35 AM.
Why not correct for inlet conditions on a supercharged car?
SAE J1995 (Gross Power) section 1.1 states it applies for ...SI naturally aspirated and pressure charged...
SAE J1349 (Net Power) doesn't restrict the use of it for a forced induction engine.
Remember the "not a dyno epxert" disclaimer...
It was my understanding that because an FI engine would boost the charge pressure well above atmospheric that the SAE correction factor didn't account for the air density change due to temperature properly (Particularly when an intercooler is used). Again, not an expert just what I have read. I guess I need to get a copy of the standard and read it thoroughly.
It was my understanding that because an FI engine would boost the charge pressure well above atmospheric that the SAE correction factor didn't account for the air density change due to temperature properly (Particularly when an intercooler is used). Again, not an expert just what I have read. I guess I need to get a copy of the standard and read it thoroughly.
No worries. All the corrections are doing is accounting for the changes to the number of molecules of the air. So water displaces it (humidity) temp by being less dense, pressure by density etc. The intercooler doesn't effect the mass flow so it doesn't effect these power corrections, they are still valid.
What they don't account for is power made by additional timing if you have an intercooler (which could be huge). So if you test on a hot day, these corrections should be done and they will be conservative. Hot day your timing is pulled for coolant or IAT's. The correction can't add that power back in. Back it can account for the crappy air mass going in. Cold day testing the reverse is true (this is assuming timing is effected and non-optimal due to octane).
I don't know if I did a good job explaining that.
There are more issues as well with boost effects on blower performance etc.
There are for sure pitfalls to it. NA and the ability to run optimal timing by not being limiting by octane would give the best corrections.
Originally Posted by Sssnake
Remember the "not a dyno epxert" disclaimer...
It was my understanding that because an FI engine would boost the charge pressure well above atmospheric that the SAE correction factor didn't account for the air density change due to temperature properly (Particularly when an intercooler is used). Again, not an expert just what I have read. I guess I need to get a copy of the standard and read it thoroughly.
The dynojet has a weather station built into it. The same day a stock 04 V dynoed 325 rwhp.
I am running 94 octane which likely gains "around" 20-25 rwhp over a 91 octane tune. The numbers are stout for my mods but add in the octane and a great tuner and yes those are the numbers.
The car has no issues pulling on a stock V2. I do believe that the dyno numbers are accurate. We will see what gains I see from headers next. Even if they werent accurate, I have a good base line for upcoming mods. The car trapped 119.6 mph. The E.T. and 60 foot werent good as I was afraid of breaking the rear end, but the mph makes me believe that the rwhp is accurate given the power and weight of the car. The same day a stock V2 with Corsa trapped 116.x mph.
Maybe I have a good runner or maybe there is something else done to the motor that I am not aware of. I bought the car modded and the prior owner dumped all kinds of $$ into it but was vague on the mods.
Yes!!! Get those stock cats out of the way ASAP... It's worth at least 15hp.
Stock pulley on my MP112 but cammed and headers in and I crushed 498hp in Texas heat.
Even at 500hp though... I rolled with a V2 on Thanksgiving last year and I wouldn't call it pulling on him easily. Three runs in a row with a max of two cars on him well into the 130mph range. Now granted, I don't know if anything was done to the car or not, but it was a pretty tasking set of runs.
Mainly finding fifth on a hard shift was a beach... I hadn't exactly been practicing hitting fifth gear very often. You kinda get that tingling in your ballz that says... "man I hope this isn't reverse" when you release the clutch.
Yes!!! Get those stock cats out of the way ASAP... It's worth at least 15hp.
Stock pulley on my MP112 but cammed and headers in and I crushed 498hp in Texas heat.
Even at 500hp though... I rolled with a V2 on Thanksgiving last year and I wouldn't call it pulling on him easily. Three runs in a row with a max of two cars on him well into the 130mph range. Now granted, I don't know if anything was done to the car or not, but it was a pretty tasking set of runs.
Mainly finding fifth on a hard shift was a beach... I hadn't exactly been practicing hitting fifth gear very often. You kinda get that tingling in your ballz that says... "man I hope this isn't reverse" when you release the clutch.
What boost and what rwtq did u make? You'd easily be over 500 with a pulley. The V2's are very heavy!
What boost and what rwtq did u make? You'd easily be over 500 with a pulley. The V2's are very heavy!
Boost: Honestly, I don't monitor it. Let's call it 6.x psi.
Numbers: 498hp / 480tq. Not really worried about chasing the number. It's been a hell of a ride, but I think it's time to turn it over to someone who wants to run it to the grave or get crazy with it from here.
Going to go with the 2.7 pulley (from 2.8) , 20% e85 and have it re-tuned. I have the stock pump with Kenny Bell BAP.. My tuner says he thinks it should be OK. Will report back later this year when funds free up. MP112 on 6ish lbs. I had the heads worked and the compression came down to 10.1
07-20-2016, 12:55 PM
