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Unless you're talking a supercharger nothing will add enough power to really change the numbers that much though.
(and a supercharger has its own drivetrain loss from how it's driven, so perhaps not even then)
Just to toss out some math:
Stock:
306 at the crank
265 at the wheels
drivetrain loss= ~13.4%
With an intake we assume a 5 hp gain so-
311 at the crank
270 at the wheels
drivetrain loss= 13.2%
That's pretty f'ing minor. But lets go nuts... I/H/and E. So about 25 hp.
331 at the crank
290 at the wheels
drivetrain loss=~12.4%
Still not what I'd really call significant. A 1% difference from stock.
you're right, significant was the wrong word. Although your assuming the most MINIMAL gains from intake/exhaust/headers. With a full header-back exhaust, the right intake, and PPE headers, I say your looking more towards 35 hp.
btw, just a shot in the dark here, but u dont happen to be knightshade do you?
Originally Posted by anthrax144
I guess I've never asked or heard this question answered but is adding mods (intake, exhaust, etc...) adding to the crank hp or just reducing the drive train loss %? For example, by adding' an intake, does the crank hp go up to 311 from 306 or does the drive train loss % go from 13.4% (265 vs 306) to 11.8% (270 vs 306)? I was always under the impression that items such as intake and exhaust were a component of the drive train loss so by adding aftermarket parts you were actually making the car more efficient hence reducing drive train loss but not actually affecting the crank hp. Only mechanical additions (turbos, superchargers, nitrous, etc..) would actually increase the crank hp. Please feel free to correct my understanding.
any mod that "increases hp" does so at the crank and at the wheels. With every mod the PERCENTAGE of drivetrain loss is slightly reduced, but only because the ratio of wheel hp to crank hp becomes bigger since nothing was done to reduce drivetrain loss
btw, just a shot in the dark here, but u dont happen to be knightshade do you?
He is...
Originally Posted by iTaLiAnO
any mod that "increases hp" does so at the crank and at the wheels. With every mod the PERCENTAGE of drivetrain loss is slightly reduced, but only because the ratio of wheel hp to crank hp becomes bigger since nothing was done to reduce drivetrain loss
That makes sense. I suppose drive train loss has more to do with the transmission, axles, and differentials than anything else.
The reason I went with those +hp numbers is because I believe them to be correct.
I've yet to see anyone dyno +35 hp from bolt on mods.
265 is pretty solid as the "stock" number...The highest dyno I can recall seeing for a 350 with bolt ons (intake/exhaust/headers) is about 290.
Which is +25, not 35.
breaking down individually-
Intake is 5 tops
Exhaust is 7-10 depending on legality
Headers are 10-15 (I think even PPE doesn't claim more than 16, and most dynos show less)
So 22-30 is really the range but they're not necessarily all fully additive... so 25 is reasonable by component, and seems consistent with the real world dynos done with those mods.
Either way, drivetrain loss doesn't vary much with these minor add ons.
i dont consider an axleback a legitimate exhaust. so im thinking 10-15 hp is more realistic when talking about a real exhaust. and if ppe headers are 16, then call it 16.
5 + 15 + 16 = 36
and maybe answering my question instead of debating over 10 hp or challenging the word significant might make u come off as a little less bitter. just my opinion
which is weird, because legally, they're the only ones that are.
Originally Posted by iTaLiAnO
so im thinking 10-15 hp is more realistic when talking about a real exhaust
Can you show me any dynos from someone other than the guy trying to sell you an exhaust that shows 15 hp for the 2IS? Ideally more than one person of course, because you'd think anything that offered 1.5-2x more hp than anything else would get a few customers...
But I sure haven't seen one.
Originally Posted by iTaLiAnO
. and if ppe headers are 16, then call it 16.
5 + 15 + 16 = 36
but they're not 16 for most people. 10-12 shows up in most dynos I've seen of the PPE headers. The only +16 dyno I've seen was the guy who worked with PPE in the development of the headers...nobody's duplicated that # that I've seen... if you have by all means where's the link to the dyno sheets?
Plus, as I mentioned, nobody who has all 3 things has shown gains above 25 hp total... which is exactly in line with 5 (intake), 7-10 (exhaust) and 10-12 (PPE headers).
Originally Posted by iTaLiAnO
and maybe answering my question instead of debating over 10 hp or challenging the word significant might make u come off as a little less bitter. just my opinion
Now I think you're projecting
All I've done is present the actual, known, facts.
Including the dyno info others have provided, and the math relevant to the topic.
A 1% difference in drivetrain loss is not significant, or really worth worrying about... which makes your initial insistence that the drivetrain loss number only be applied to stock vehicles not really valid.
Not sure what question you're claiming has gone unanswered though, don't see one from you in the thread that hasn't been answered
As for the bulk this thread; there really is no way to correlate drivetrain losses using set values. Simple things like tire compound, tire pressure, tire wheel mass, rate of acceleration, oil temperatures, gear ratios, operator methods all influence losses that are not easily compensated for by say even 3 2IS 350's pulling 4 runs each on the same treadmill in the same day. There will be variations
The bottom line is does it set the driver back in their seat making them grin from ear to ear and stuff like that.
OK, so this doesn't answer the drive train power loss question but it does show a calculation vs real world data comparison of what is happening in our trans and diff.
A couple of constants:
1 mile = 5,280' or 5,280 * 12 = 63,360"/mile
If we take our 255/40/R18 tire and do some calculations (or measure it) we find it's roughly 26.03" in diameter. From this:
26.03" X 3.141593 = 81.7756" circumference.
63,360" per mile / 81.7756" = 774.8027 revolutions per mile.
Now we take our 4.083:1 diff and get the input shaft speed.
774.802 revolutions per mile X 4.083 = 3163.5194 rev's per mile at 60 mph
Drive Shaft 3163.5194 Rev's per min / 60 min = 52.7253 rev's sec.
Now look at some live data from Fusion App. On the left we have the Engine RPM at 2,323RPM and input shaft RPM at 2,300 RPM into the trans after some loss through the torque converter even though it is in Lock up as seen by the #1 at the bottom. Nope, no loss there. lol
The input into trans is 2,300 RPM. Trans is in 6th gear. See Chart Below. Now look back up at the Speed of the transmission output shaft as reported by the trans TCU to Fusion "Speed of NO" = 3,900 RPM and look at the vehicle speed @74mph as reported by the app.
Finally | Vehicle speed = 74 mph X Shaft speed of 52.7253 rev's min = 3901.6739 RPM which is what the app says at that speed. See chart for 6th gear ratio.
Notice on this chart I used 2,300 RPM as the input into the trans bypassing what was lost in the Torque Converter. Mind you this app shows numbers like Engine RPM vs Speed of NT as having a difference of 1,200 to 1,600 RPM when launching. Someone paid more than me can calculate the loss while in the in fact the converter is doing its magic slipping. Hint it is not in lockup while at WOT.
Not responsible for conversion errors. Lunch is over and I need to go!
03-10-12, 08:35 AM
Charts and real world Data
