flywheel or Rear-wheel?
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Most of my post above explaining hp and dyno's.
Also there is not set amount as a percentage thru dirvetrain loss. Even tyre pressures can have an effect and according to Newton's laws of physics every action has an equal and opposite reactrion.
Also where are they getting 355fwhp from, not there really is such a thing as fwhp anyhow (also explained in my above post).
Also as Dynojets are very optimistic in deriving HP, figures from such dyno's should not be taken literally and converted into what someone believes the engine is making in SAE Net.
Also there is not set amount as a percentage thru dirvetrain loss. Even tyre pressures can have an effect and according to Newton's laws of physics every action has an equal and opposite reactrion.
Also where are they getting 355fwhp from, not there really is such a thing as fwhp anyhow (also explained in my above post).
Also as Dynojets are very optimistic in deriving HP, figures from such dyno's should not be taken literally and converted into what someone believes the engine is making in SAE Net.
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i disagree.
its entirely possible that some LS1's which are stock are making that kind of power at the flywheel. The LS1 in the corvette was rated at 340-350 hp and im sure GM allowed for some production variances.
what happens when you put out a vehicle that doesn't live up to the hp its "rated at"??? anyone remember why there was no 2000 Cobra?? and why there was a service bulletin for the 99's?
Gm will slightly underrate engines to reflect what the Mean output of a line of engine will be just to avoid situation the mustang cobra experienced
we all know some cars just run better than others, slight differences in engine due to them being mass produced in entirely possible to have differences either more power than what its rated at and even lower than what its rated at
its entirely possible that some LS1's which are stock are making that kind of power at the flywheel. The LS1 in the corvette was rated at 340-350 hp and im sure GM allowed for some production variances.
what happens when you put out a vehicle that doesn't live up to the hp its "rated at"??? anyone remember why there was no 2000 Cobra?? and why there was a service bulletin for the 99's?
Gm will slightly underrate engines to reflect what the Mean output of a line of engine will be just to avoid situation the mustang cobra experienced
we all know some cars just run better than others, slight differences in engine due to them being mass produced in entirely possible to have differences either more power than what its rated at and even lower than what its rated at
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about yal question on the ram air it works from 65 to 90 mph anything over that and the arodynamics just chanel it over the scoops i will see if i cant find the video of it in a wind trunnel to post
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I'm pretty sure drivetrain loss is around 15% for M6's and 18% for A4's. So a 355fwhp would put you at about 302rwhp for a M6, and 370fwhp would put you at about 315rwhp. Most '01 & '02's dyno at around 315 or higher at the rear wheels, seems pretty safe to say the later model LS1's are making 370 at the fly!
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if this is what you mean than this is completely false
if you have more power, you will accelerate all those components at a faster rate as well, combined with slightly more friction from gears and what not because of the increased pressure exerted on them
to accelerate someone at a faster rate more power is soaked up accelerating these components at a quicker rate, (think tires, driveshaft, flywheel, ring, pinion, axles, brake rotors) therefore a percentage gives you a fairly decent ballpark guesstimate
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so are you saying that for a given drivetrain it takes something like 40 horsepower or some other arbitrary number to drive it??
if this is what you mean than this is completely false
if you have more power, you will accelerate all those components at a faster rate as well, combined with slightly more friction from gears and what not because of the increased pressure exerted on them
to accelerate someone at a faster rate more power is soaked up accelerating these components at a quicker rate, (think tires, driveshaft, flywheel, ring, pinion, axles, brake rotors) therefore a percentage gives you a fairly decent ballpark guesstimate
if this is what you mean than this is completely false
if you have more power, you will accelerate all those components at a faster rate as well, combined with slightly more friction from gears and what not because of the increased pressure exerted on them
to accelerate someone at a faster rate more power is soaked up accelerating these components at a quicker rate, (think tires, driveshaft, flywheel, ring, pinion, axles, brake rotors) therefore a percentage gives you a fairly decent ballpark guesstimate
think about what your saying....
before my heads and cam i had a stockish LS1 ~350 at the crank. thats about 52 hp used up by the drivetrain
now i have my heads and cam and im estimating 500 at the crank. now your going to tell me it now takes 75 hp to turn the drivetrain and push the car?
![Bulls#!t](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_bs.gif)
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WOW.
350 is estimated crank HP
280-325 is rwhp depending on drivetrain, dyno, temperature, altitude.
This is rediculous. Yall spend entirely to much time arguing about BS!
350 is estimated crank HP
280-325 is rwhp depending on drivetrain, dyno, temperature, altitude.
This is rediculous. Yall spend entirely to much time arguing about BS!
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no, it doesnt. it takes the same amount of power to turn the drivetrain no matter what engine is in front of it.
think about what your saying....
before my heads and cam i had a stockish LS1 ~350 at the crank. thats about 52 hp used up by the drivetrain
now i have my heads and cam and im estimating 500 at the crank. now your going to tell me it now takes 75 hp to turn the drivetrain and push the car?![Bulls#!t](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_bs.gif)
think about what your saying....
before my heads and cam i had a stockish LS1 ~350 at the crank. thats about 52 hp used up by the drivetrain
now i have my heads and cam and im estimating 500 at the crank. now your going to tell me it now takes 75 hp to turn the drivetrain and push the car?
![Bulls#!t](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_bs.gif)
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no, it doesnt. it takes the same amount of power to turn the drivetrain no matter what engine is in front of it.
think about what your saying....
before my heads and cam i had a stockish LS1 ~350 at the crank. thats about 52 hp used up by the drivetrain
now i have my heads and cam and im estimating 500 at the crank. now your going to tell me it now takes 75 hp to turn the drivetrain and push the car?![Bulls#!t](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_bs.gif)
think about what your saying....
before my heads and cam i had a stockish LS1 ~350 at the crank. thats about 52 hp used up by the drivetrain
now i have my heads and cam and im estimating 500 at the crank. now your going to tell me it now takes 75 hp to turn the drivetrain and push the car?
![Bulls#!t](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_bs.gif)
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
lets just pretend i could install the 3 cylinder Geo Metro XFI engine with the same tranny, rear end, etc etc into an f-body everything is the same except for this 3 cylinder engine which is rated at putting out 49 hp
with your logic that car wouldn't even move
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
think about what you are saying
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#31
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so your saying a stock LS1 F-body consumes ~52 hp to move the car?![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
lets just pretend i could install the 3 cylinder Geo Metro XFI engine with the same tranny, rear end, etc etc into an f-body everything is the same except for this 3 cylinder engine which is rated at putting out 49 hp
with your logic that car wouldn't even move![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
think about what you are saying![Bang Head](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_banghead.gif)
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
lets just pretend i could install the 3 cylinder Geo Metro XFI engine with the same tranny, rear end, etc etc into an f-body everything is the same except for this 3 cylinder engine which is rated at putting out 49 hp
with your logic that car wouldn't even move
![Rolleyes](https://ls1tech.com/forums/images/smilies/LS1Tech/rolleyes.gif)
think about what you are saying
![Bang Head](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_banghead.gif)
the 15% method is total BS. it does not take 23 more HP to turn the drivetrain over just because you have 5XX hp insted of 350 at the crank.
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thanks for proving my point. i never said it takes 52 hp to move the car. i got thoes numbers by using your 15% parasitic loss method. this is all YOUR logic.
the 15% method is total BS. it does not take 23 more HP to turn the drivetrain over just because you have 5XX hp insted of 350 at the crank.
the 15% method is total BS. it does not take 23 more HP to turn the drivetrain over just because you have 5XX hp insted of 350 at the crank.
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Why wouldn't you? If an exhaust causes the engine to produce 20 more hp then it would be making 17 more hp at the wheels which is very noticeable. It's not nitpicking, it's basic Newtonian physics. If anything, the percent of power lost may even increase a little at higher levels of power due to increased heat production.
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thanks for proving my point. i never said it takes 52 hp to move the car. i got thoes numbers by using your 15% parasitic loss method. this is all YOUR logic.
the 15% method is total BS. it does not take 23 more HP to turn the drivetrain over just because you have 5XX hp insted of 350 at the crank.
the 15% method is total BS. it does not take 23 more HP to turn the drivetrain over just because you have 5XX hp insted of 350 at the crank.
we're not talking about "turning the drivetrain over" we are talking about accelerating the various parts of the drivetrain
when your on a dynojet chassis dyno not only are you trying to accelerate the heavy *** metal drum, you are also using power to accelerate the moving parts in your drivetrain
your engine is trying to accelerate the flywheel, input/output shaft of the transmission, driveshaft, ring and pinion, axles, brake rotors and the wheels and tires. All of these things have mass and need a certain amount of power to accelerate them at a certain rate.
the amount of acceleration is the main variable in that equation we are looking at, if you increase the horsepower of the engine you will then accelerate the drivetrain parts at a quicker rate, thus more power will be consumed trying to accelerate those parts at that quicker rate
if you could increase the power at the crank by exactly 100 hp, you will not see all of that extra 100 hp at th rear wheels, because that extra power, increases the rate of acceleration of moving parts which takes power
are you seeing what im getting at or not?
Last edited by 1994Z28Lt1; 05-22-2008 at 12:50 AM.
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Sorry that's a bit of a sweeping statement, but I'm a total car NUT and frequent many automotive forums. However it doesn't matter what the make or model is, if it's in the US then the manufacturer seems to have underrated it.
Sn95 Mustang owners claim this because a Dynojet often gives them 240rwhp on a 260bhp SAE Net motor. Totally ignoring that a Mustang dyno gives them a much more realistic 220-225rwhp reading.
Mach 1 owners claim there car is underrated.
2003/4 Cobra owners claim the same
Lt1 Fbody owners claim there car is underrated
s197 Mustang owners
5.0 Fox Stang owners
Viper owners
This doesn't even touch on the cars from the 60's and early 70's. - every single one of them apparently underrated.....
The list goes on and on.
And all I've ever seen is people taking Dynojet numbers, usually uncorrected with no graph smoothing and simply saying 15% drivetain loss = my car is really more powerful than the maker claims.
Thing of it as someone saying hay I've $100,000 but forget to mention that its not USD ($) but Australian dollars.
It might be HP but its not the same thing.
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The funny thing is that is exactly the claim everyone in the US seems to make.
Sorry that's a bit of a sweeping statement, but I'm a total car NUT and frequent many automotive forums. However it doesn't matter what the make or model is, if it's in the US then the manufacturer seems to have underrated it.
Sn95 Mustang owners claim this because a Dynojet often gives them 240rwhp on a 260bhp SAE Net motor. Totally ignoring that a Mustang dyno gives them a much more realistic 220-225rwhp reading.
Mach 1 owners claim there car is underrated.
2003/4 Cobra owners claim the same
Lt1 Fbody owners claim there car is underrated
s197 Mustang owners
5.0 Fox Stang owners
Viper owners
This doesn't even touch on the cars from the 60's and early 70's. - every single one of them apparently underrated.....
The list goes on and on.
And all I've ever seen is people taking Dynojet numbers, usually uncorrected with no graph smoothing and simply saying 15% drivetain loss = my car is really more powerful than the maker claims.
Thing of it as someone saying hay I've $100,000 but forget to mention that its not USD ($) but Australian dollars.
It might be HP but its not the same thing.
Sorry that's a bit of a sweeping statement, but I'm a total car NUT and frequent many automotive forums. However it doesn't matter what the make or model is, if it's in the US then the manufacturer seems to have underrated it.
Sn95 Mustang owners claim this because a Dynojet often gives them 240rwhp on a 260bhp SAE Net motor. Totally ignoring that a Mustang dyno gives them a much more realistic 220-225rwhp reading.
Mach 1 owners claim there car is underrated.
2003/4 Cobra owners claim the same
Lt1 Fbody owners claim there car is underrated
s197 Mustang owners
5.0 Fox Stang owners
Viper owners
This doesn't even touch on the cars from the 60's and early 70's. - every single one of them apparently underrated.....
The list goes on and on.
And all I've ever seen is people taking Dynojet numbers, usually uncorrected with no graph smoothing and simply saying 15% drivetain loss = my car is really more powerful than the maker claims.
Thing of it as someone saying hay I've $100,000 but forget to mention that its not USD ($) but Australian dollars.
It might be HP but its not the same thing.
Also, just about every dyno graph posted is SAE. and smoothing either has been applied or usually won't cause more than a few hp difference with is negligible. Every time someone posts a graph without SAE numbers or smoothing about 15 people point it out in the first page of the thread.
And back in the 60s and 70s everything was underrated to keep insurance rates down so people will buy their cars.
#38
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But that aside, I truly believe any Fbody Ls1 makes a genuine 320-350bhp SAE Net. The "advertised" figure was a whole lot cheaper option than really detuning the engine.
And yes apples to apples. But its so rare that it happens. As there are way too many variables. As not every graph post (or even the majority) are anywhere near using the same standards.
It stands on several reasons:
-Even without engine alterations when cars where rated at SAE Net and not Gross they lost a lot of HP, sometimes over 100hp.
-If they really produced that kind of power why the hell where those cars not WAY faster. And no, citing the tyres is not an excuse, because today old cars run modern tyres.
-Are you seriously saying that an old OHV lump with it's origins in the late 40's early 50's, using no form of CAD or CAM, with pretty poor manufacturing tolerances (by today's standards) actually produce more specific hp (bhp/litre) than modern engines like the Dodge Hemi and the LS7?
Interesting reading:
SAE gross horsepower
Prior to the 1972 model year American automakers rated their engines in terms of SAE gross horsepower (defined under SAE standards J245 and J1995). Gross hp was measured using a blueprinted test engine running on a stand without accessories, air cleaner, mufflers, or emissions control devices and sometimes fitted with long tube "test headers" in lieu of the OEM exhaust manifolds. The atmospheric correction standard (e.g. barometric pressure, humidity and temperature) that was utilized in obtaining the Gross ratings was more idealistic than that which is used under the SAE net rating system. The resulting Gross power (and torque) figures therefore reflected a maximum, theoretical value and not the power of an installed engine in a street car. Gross horsepower figures were also subject to considerable adjustment by the manufacturer's advertising and marketing staff under the direction of product managers. The power ratings of mass-market engines were often exaggerated beyond their actual Gross output, while those of the highest-performance muscle car engines often tended to be closer in actual output to their advertised, Gross ratings. It should be noted that no pre-1972 "muscle car" engine in its unaltered, production line stock form and in its as "as installed" (SAE net) condition has ever yielded documented, qualified third party validated power figures that equal or exceed its original Gross rating. Claims that such engines were "under-rated" are therefore highly dubious. It is therefore more accurate to say that the ratings of the highest performance engines from that period tended to be less exaggerated than those of more typical passenger cars, but still exaggerated relative to what could be obtained in the SAE net configuration. For example, the ultra-rare and exotic 1969 427 ZL1 Chevy (rated @ 430 Gross HP) is frequently cited as one of the most "under-rated" high performance engines from that period, yet it could only produce 376 SAE NET HP. [6] It should be noted that today's various "Stock" drag racing events (e.g. "Pure Stock Drags" and the "Certified Stock" sub-grouping) allow the engines to be fully blueprinted per NHRA technical bulletins, which yields ideal tolerances and can increase actual compression ratio by more than 2 full points. These series also permit various other performance-enhancing alterations (e.g. over-bores, wide-flank cams, forged internals, stiffer valve springs, adjustable push-rods and poly-locks for optimal valve train geometry, modern exhaust systems with mandrel bent, 2.5 inches (64 mm) pipes and low restriction mufflers, fully locked differentials, etc.). Therefore, the results achieved in those events often don't reflect the performance potential (or engine output) of the car in its original, unaltered and production-line stock form.
Prior to the 1972 model year American automakers rated their engines in terms of SAE gross horsepower (defined under SAE standards J245 and J1995). Gross hp was measured using a blueprinted test engine running on a stand without accessories, air cleaner, mufflers, or emissions control devices and sometimes fitted with long tube "test headers" in lieu of the OEM exhaust manifolds. The atmospheric correction standard (e.g. barometric pressure, humidity and temperature) that was utilized in obtaining the Gross ratings was more idealistic than that which is used under the SAE net rating system. The resulting Gross power (and torque) figures therefore reflected a maximum, theoretical value and not the power of an installed engine in a street car. Gross horsepower figures were also subject to considerable adjustment by the manufacturer's advertising and marketing staff under the direction of product managers. The power ratings of mass-market engines were often exaggerated beyond their actual Gross output, while those of the highest-performance muscle car engines often tended to be closer in actual output to their advertised, Gross ratings. It should be noted that no pre-1972 "muscle car" engine in its unaltered, production line stock form and in its as "as installed" (SAE net) condition has ever yielded documented, qualified third party validated power figures that equal or exceed its original Gross rating. Claims that such engines were "under-rated" are therefore highly dubious. It is therefore more accurate to say that the ratings of the highest performance engines from that period tended to be less exaggerated than those of more typical passenger cars, but still exaggerated relative to what could be obtained in the SAE net configuration. For example, the ultra-rare and exotic 1969 427 ZL1 Chevy (rated @ 430 Gross HP) is frequently cited as one of the most "under-rated" high performance engines from that period, yet it could only produce 376 SAE NET HP. [6] It should be noted that today's various "Stock" drag racing events (e.g. "Pure Stock Drags" and the "Certified Stock" sub-grouping) allow the engines to be fully blueprinted per NHRA technical bulletins, which yields ideal tolerances and can increase actual compression ratio by more than 2 full points. These series also permit various other performance-enhancing alterations (e.g. over-bores, wide-flank cams, forged internals, stiffer valve springs, adjustable push-rods and poly-locks for optimal valve train geometry, modern exhaust systems with mandrel bent, 2.5 inches (64 mm) pipes and low restriction mufflers, fully locked differentials, etc.). Therefore, the results achieved in those events often don't reflect the performance potential (or engine output) of the car in its original, unaltered and production-line stock form.
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When you're making more horsepower, you're doing more work per unit time. The rated horsePOWER of the engine indicates the amount of work the engine can produce per unit time. Torque and horsepower are intrinsically related. Friction from the surface is what moves the automobile. The greater the force you can give the rotating tires, the greater the ground will propel the car. When considering two engines with a disparity in horsepower rating and all other things being equal, I don't see how the total friction from the bearings and everything would magically increase for the engine that makes more horsepower. The inertia of the drivetrain pieces wouldn't magically increase either. Someone correct me if I'm wrong. There are some things I could be overlooking.