m21sniper

Mark: "what about the MAF? if you have one, it aint no 1983 US"

When i use the term 'MAF' it's just a generic term for an air metering device. My appologies for any confusion that may have caused.

"hey, we all know what it takes to do a 13 second 1/4 run."

There is a vast difference between a 13.67 best ever time(which my car ran) and a consistent 13 flat. About 70 horsepower as a matter of fact. Please don't misrepresent my claims. 13 flat is where i want to be AFTER i install a 75 shot of nitrous.

"and it aint no 1983 stock 4.7 US 928!"

And have i not stated QUITE CLEARLY that my engine is not stock numerous times? And have i also not stated that i have no idea what modifications the PO made other than the custom aluminum radiator and transmission modification?

" it does take around 300hp on a 3300lb chassis."

Did i also not mention that my car was over 300lbs lighter than stock many times?

"1983 928 rarely put down more than 200hp at the wheels stock. so, where did 50hp come from?? id say, that "giagantic" MAF is a good place to start!"

300+ lbs in curb weight no doubt accounted for quite a lot of it. About .5 seconds worth vs a stock car.
The Borla XR-1 offroad exhaust, losing three belt driven accesories, advancing the timing, and increasing fuel pressure clearly also account for some of the rest- perhaps another .5 seconds.

The rest of my ET difference vs stock is the unknown part. Unknown to everybody but the original owner- whom i never met(i bought my car at a dealer only auction, i am the second owner).

I would surely love to know what's been done exactly- but i am not about to disassemble my engine just to satisfy my curiousity, or to shut up the skeptics(that would be you Normy).

If you go to http://members3.boardhost.com/928s4vr/ and post a thread to Heather, you can ask her how much i beat her mildly modified 1983 US A/T by. Or you can just ask Lance- who posts here- as he was there.

I have two witnesses that've seen my car run, one owned a 1983 Euro with a 75hp shot of nitrous, and i beat him by 3 lengths from a standing start. He's ALREADY conveyed that story on this forum. The other is Heather, who i beat by a full 12 lengths.

Very rarely can a posters claims be verified by 2 two known individuals- mine can.

m21sniper

BCDavis: "And didn't Devek build a few 2v strokers, that no one knew where they were, or who owned them?

I mean, there is no reason to call BS on someone who seems to be honest.

We may not know why it's so fast, and it's interesting to find out,
but there is no reason to badmouth someone who is just talking
about how their car is strangely faster than other 928s...

He's got the timeslip to prove it.

I don't smell anything other than burning rubber."

Thanx man, i appreciate the support. Believe me, if i was gonna lie about my 1/4 mile time it would be a hell of a lot faster than a fairly pedestrian best ever run of 13.67@103.1mph.

I have two verifiable witnesses that've run against my car, if that's not enough, then hey, that's someone else's cross to bear- not mine.

mark kibort

why is there a "giagantic" MAF??? he said it , not us. im sure he is running as fast as he says he is. why is the question! we are all curious for the answers.

MK

mark kibort

you said "giagaintic MAF" . the AFM is pretty tiny if it is a stock 1983 US. (opening is 1.75" by 2")

I was talking 13s in general . 13.7 is still very fast for any stock 928, even an S4. the S4 specs out at around 13.4.

300lbs is worth about 20-30 hp for our discussions, and surely thats part of it. did you weigh your car? is it 3000lbs empty??

borla or any exhaust mods probably 12 hp max ( i did this and went from stock to 3.5" pipe. same gains as headers.)

pulleys: not taking much hp. maybe 1-2 for everything. PS pump doesnt draw anything unless you are turning, and you still have this. alternator, minimal, air pump, almost nothing, driven fan, maybe 1hp. combined inertias, also almost nothing. a rounding error on a dyno.

we all believe your car is fast, just searching for why.

Mk

m21sniper

FROM THE 3d POST IN THIS THREAD:

"hey sniper its lance from new jersey. my setup was a 75-100 shot. for the euro. thinking of doing it on my 79. andrew and mark have great amount of knowledge on this. if you up your fuel flow you should be fine (safe) with 75-100hp. let me tell you guys sniper has a very very fast shark. he spank my 83 euro from a dead stop by 2-3 cars."

So tell me Normy, is lance a liar too?

Here is a post from Heather at the other board(she has a midly modded 1983 928S US A/T):

"Yeah, unfortunately i can verify what sniper said about his "freak of nature" 928. He destroyed me in a run (but to my behalf it was only a month after i got the car, so my time might be a little better now )

Snipes 928 has a different feel then driving mine (yeah he actually gave me the keys once ) if i can figure out what it is, i'll do the same to mine! "

http://members3.boardhost.com/928s4vr/msg/44630.html

And from lance at the same board:

"i second that for sniper. i personally think some one shimmed his tranny to increase the stall speed. thats why when you purchase the shark because someone returned it not knowing the tranny was low on fluid. from a stand still sniper put about 2 cars on me. i have no doubt that his car is way faster than any stock s4. or even lightly modded s4."

http://members3.boardhost.com/928s4vr/msg/44628.html

I rest my case, and i will not be addressing any further claims that i'm exxagerating my 928s performance. If any one still doubts my claims after all the evidence i've provided, then there's no point in arguing with you because you'll never be convinced short of giving you a ride personally(and anyone who posts here that lives in the Philly area is welcome to a ride anytime they wish regardless).

mark kibort

Ill give you the cliff notes on gearing efficiency, and if you have any doubts, see your local physics teacher, race book , or read the 100posts on the topic a month or two ago.

gearing doesnt create hp and thats what you need for a quick 1/4 mile run. However, it does make more more efficient the hp you do have to the wheels over the operational range. (speed range) more accurately said, its ave hp to the wheels over the speed range. in your case, its 0-103mph. you want as many gears as possible in this range to keep the engine near max HP for as much of the time as possible. if you have a 3 gear or a two gear run to 103mph, you want the last gear to be near redline . EVEN if it means making a taller rear end. (numerically lower, i.e. 2.2 compared to 2.75). there are trade offs. in fact, you mention going to a 4.5:1 rear end to make your last gear redline at 103mph. this would be fine if you could change the ratios of the gear box. with 4.5:1, you would have a 1st and 2nd that could basically be unusable (too low) and then the spacing for the next few gears could be the same as a stock car going to 2nd or 3rd depending on the cars were car comparing it too.

in fact, a 2.2 compared to a 3.09:1 in an GTS 5 speed, gives a much shorter 1st, and then a taller 2nd compared to a S4 in 1st gear to the same realative speeds. THEN, guess what, all the gears match up numerically all the way to 4th in the S4. meaning, you just changed the rear end from 2.2 to 3.09, yet nothing was accomplished except a 12:1 total ratio 1st gear to 30mph (great for a launch if you have tires to take advantage of it) then, you are at a disadvantage or equal all the way to 145mph!!

So, you statement of gearing making more torque in any gear is only part right. gear for gear, yes, but speed for speed , no, and thats what we care about. (who cares what gear we are in, we care what the actual ratio to the wheel is!) a great comparison of this is the 2.2 to the 2.75:1 gear boxes. effectively less of a difference in the gear boxes due to internal ratio changes, so, lets call it 2.2 to 2.4:1, because this is the true difference. (about 8% per gear) However, you dont get 8% more HP or torque over a speed range say, 0-118mph for a 12 second 1/4mile! here is why:

S4
1st gear 0-56mph
2nd gear 56-84mph
3rd gear 80-118mph

GTS
1st gear 0-49
2nd gear 49-73
3rd gear 73-104
4th gear 104-118 (and can go up to 133mph)

comparisons of torque to the wheels over time
0-49mph advantage by 15% to the GTS, HOWEVER 49mph to 56mph now is an even bigger advantage for the S4, albeit for a shorter time. THEN, from 56 to 73mph, the GTS has the 15% advantage, but from 73mph to 84mph, the S4 has the bigger advantage for the shorter time again. THEN, at 84mph, the GTS has the advantage until 104mph, but from 104mph, to the 118mph target speed, the S4 would have a much larger advantage till the finish line.

what does this all mean, it means there are trade offs at different speeds. all this changes dramatically if both cars instead of having 400hp (as the example would indicate) would have only 320hp. this means the target speed and expected speed would be near 100mph, and ET of near 13.5 seconds. this would give more of the advantages to the GTS gear box and ratios.

Its all about areas under the curve. meaning its the total or average force exerted to the wheels over time.

its not how you say below, as the greater multiplcation of torque at all engine speeds. Ive just proved this COMPLETELY incorrect.

the miracle of gear reductions. think of them as creating greater efficiency of the engine hp to the wheels. Also, think of a infinitely variable transmission. it would ramp up to max hp and stay there, not operating EVER at max engine torque, but always at max engine HP. The net torque to accelerate the car would be at any moment in the speed range, the gear ratio x the torque of the engine at max HP.

there are some great charts on the other thread as we all beat this one to death, mostly with sematics. (due to my post that gearing has no effect on performance. ) however, i was trying to make a point about gearing is very important on gaining efficiency on how the engine hp is transfered to the wheels and accelerates the mass of a vehicle, but doesnt "create" hp by its self. there are trade offs with gear boxes. all you have to do to see how much accelerative force you have , is take any speed and work through the gear boxes and see what torque you produce to the wheels. its not as cut and dry as you may have illuded to . gearing is very specific for the target speeds of any distance and the spacing of the gears in the gear box. this also why a cup car has a 8% advantage with the same engine hp , because with its extra gear between our 2nd and 3rd, it gets 8% more hp to the wheels due to the closeness of the gear box in that range.

mk



([QUOTE=m21sniper]"

(mark said) "its the ave torque to the wheels over the speed range. (area under the torque curve used.) you say you go through 2 gears from 0-100mph. right now with your hp, you have an optimal gearing. assuming your 1/4mile top speed is 100mph."

(m21sniper said)My 928s best ever trap speed is a 103.1mph.

My IDEAL 1/4 mile gearing would leave me just short of redline in top gear at the end of the 1/4 mile. I'd need about a 4.56:1 for that. The extremely high gearing of 928s is what really hurts them as 1/4 mile cars. With no other change but a 4.56:1 rear end ratio any 928 would be much faster in the 1/4 mile(perhaps as much as 2 seconds assuming traction can be maintained, which it most certainly would not), at a great expense to top end(perhaps as much as 40 or more MPH).

Torque multiplication is purely a function of gear ratio. A lower gear ratio provides greater torque multiplication at all engine speeds, end of story.

m21sniper

"you said "giagaintic MAF" . the AFM is pretty tiny if it is a stock 1983 US. (opening is 1.75" by 2")"

It's much bigger than that, but i've never measured the ID(the ID is perfectly circular btw, it's not elongated or ovular such as your above dimensions suggest). Next time i have the airbox off i'll get in there with a mike and take a measurement for ya, and see if i can find any part numbers on it.

"I was talking 13s in general . 13.7 is still very fast for any stock 928, even an S4. the S4 specs out at around 13.4."

That's actually MUCH faster than the published times for an S4. Is 13.4 the actual track number for stock S4s? Just curious.
According to this link a stock S4 runs about a 14.5
http://www.dragtimes.com/Porsche--928-Drag-Racing.html
That's pretty consistent with the published figures i've seen for S4s on other sites. 13.5 is more along the lines of GT performance, again, based on published figures.

I'm not doubting you, just seeking some clarification.

"300lbs is worth about 20-30 hp for our discussions, and surely thats part of it. did you weigh your car? is it 3000lbs empty??"

It should be well under 3000 based on the official NADA published curb weight of 3210lbs for a 1983 928S
http://www.nadaguides.com/uv/viewres...wPr=1&wPg=2032

Based on that figure, i should be a hair under 2900lbs sans driver.

As a general rule of thumb on a 4000lb car every 100lbs equates to .1 second improvement in ET(as does a 10hp SAE increase in HP). More for a lighter car, less for a heavier car. Considering that my 928 is much lighter than 4000lbs to start out, 320ish lbs(which is my most accurate guesstimate for my weight reduction measures) should easily equate to at least a .5 reduction in ET(which is fully supported by actual timed runs).

"borla or any exhaust mods probably 12 hp max ( i did this and went from stock to 3.5" pipe. same gains as headers.)"

I lost the cat and resonator too, and went with an off-road XR-1 Borla muffler.(ie, the exhaust system is totally illegal) I'm sure it was at least 25-30hp SAE net difference(which is about typical for any performance V-8), probably about 60% of that at the wheels, or about 15-18rwhp. The difference in apparent acceleration after the exhaust was installed was far more than i expected- which suggests that there were internal mods that greatly benefited from the increased exhaust flow.(PS: My car does have the 85-up style headers, they were already installed on the car when i got it)

"pulleys: not taking much hp. maybe 1-2 for everything."

At 6000rpms three belt driven accessories gobble lots of power(particularly when one of them is A/C as was the case with mine). I wouldn't want to put a number on it, but 1-2 hp is utterly ridiculous. If i had to guess i'd put the number at more like 10-15 SAE HP(or about 60% of that figure at the wheels, or about 4-9rwhp).
I can tell you that when i had my 1978 4 speed El Camino(powered by a 1972 350cid/370horse Vette LT-1 motor) that when i switched from the OEM clutch fan to an electric i got a full .2 second improvement in actual ET- with no other change. That's pretty common, which is why so many people install electrics in place of factory clutch fans. It's a simple yet proven performance enhancement.

"we all believe your car is fast, just searching for why."

The funny thing is i DON'T consider it to be that fast. It's one of the slower performance cars i've ever owned, to be honest. It is however, the total package- which is why i like it so much.

My best guess as to the mods?

It's a stroker motor with Euro(or custom) cams and fairly extensive head and intake plenum port/polishing work....but that's just an educated guess.

I don't dwell on it because i'm simply not about to yank the motor and take it apart just to find out, and because quite honestly, i do not consider a 13.67 particularly fast to begin with. My three previous cars were all low to mid 12 second machines(78 El Camino- 12.7 , 83 Buick T-Type Turbo- 12.4, and 68 Pontiac LeMans ZZ4- 12.1).

All i'm looking for is a Q&A with an actual 928 nitrous user, the rest of the discussion quite frankly doesn't much interest me because i've already had these discussions many times on other 928 boards in the last three years(and god knows how many dozens of emails from 16v 928 owners that want to mimic my timeslips). I understand your curiosity, and appreciate the interest, and have done my best to be as forthcoming and honest as i can, but if i hear one more clown(Normy) tell me i'm FOS i'm gonna sell the damned thing and buy a Subaru Forrester XT...they run a 13.8 right from the showroom floor.

LOL...

Normy

Yeah, well....I'm still smelling a cattle farm.

Listen sweety...Normy's 928S2, a car originally sold in Europe with 10.4:1 compression, bigger valves, WILD factory cams, a far better ROW intake, and most importantly, a 5 speed manual transmission with 2.73 gears on the rear end [2200 rpm @ 60 mph in 5th], a Borla dual exhaust, and an Ott X-pipe did a best of 13.86 @106 mph with serious bang-shifting on a cool day in Orlando a few years ago. Most runs were around 14.0, trap speeds typically in the 102 to 104 range. This car has 310 hp from the factory, but rumored to be closer to 330 on most dynos with a stock exhaust. Since mine has mods, your guess is as good as mine as to what comes out of that engine but it is certain to be around 100 more ponies than what comes out of yours, in stock form.

Not that it matters, but I'll believe you when you post the time slips, and a video showing your car creating this time slip. Thanx, and have a nice day~

N-

mark kibort

see my inserts below>>>>>>>

[m21sniper]"you said "giagaintic MAF" . the AFM is pretty tiny if it is a stock 1983 US. (opening is 1.75" by 2")"

It's much bigger than that, but i've never measured the ID(the ID is perfectly circular btw, it's not elongated or ovular such as your above dimensions suggest). Next time i have the airbox off i'll get in there with a mike and take a measurement for ya, and see if i can find any part numbers on it.

>>>>>>>>>>>>>>>>>>>well, if that doesnt tell us A LOT, then nothing does. the AFM for the US is 1.75" x 2" square. not round. something is up there. Euro uses a 3.5 " MAF hot wire set up. (only 1984 and later)


It should be well under 3000 based on the official NADA published curb weight of 3210lbs for a 1983 928S
>>>>>>>>>>>>i dont care what the NADA published, ive made 4 928 race cars and they weight 3350, and after you gut the obvious, it gets down to 3050lbs (empty) give me what you removed and ill tell you what you weight. Of the 4 cars i help build, all of them weighed 2700 to 2800lbs. (and everything in between up to 3450bs for my partially gutted to start S4)



I lost the cat and resonator too, and went with an off-road XR-1 Borla muffler.(ie, the exhaust system is totally illegal) I'm sure it was at least 25-30hp SAE net difference(which is about typical for any performance V-8), probably about 60% of that at the wheels, or about 15-18rwhp
>>>>>>>>>>>>>>again, i did the headers on a 84, it was 12 rear wheel hp, with no cat. then, removing the cat bypass and replacing the entire stock muffler, it was another 12hp. 24hp for headers and straight through exhaust

"pulleys: not taking much hp. maybe 1-2 for everything."
At 6000rpms three belt driven accessories gobble lots of power(particularly when one of them is A/C as was the case with mine). I wouldn't want to put a number on it, but 1-2 hp is utterly ridiculous. If i had to guess i'd put the number at more like 10-15 SAE HP(or about 60% of that figure at the wheels, or about 4-9rwhp).
>>>>>>>>>>>>>>>ive tested it, and you can easily calculate it. its not the frictional loads of the alternator and AC and air pump or even the fan, its the inertial loads and they are negligible over a 3-5 second range in each gear. as you may know, its less and less as the acceleration rate goes down. (ie as you go faster. it could be 10hp at 0-30mph, but only 1hp at 90mph to 100mph.)
the alternator is pretty simple. if its producing 20 amps ,then thats 280 watts. it may take 500 watts to make it, so the load on the engine is still only .75hp. the mass acceeratoin forces are easy to calculate and are very low. Ive popped off the alternator, AC, smog pump and driven fan and saw less than 2hp change. but then again, why would i see more???? the fan is the greatest draw, even though its clutch driven and lags behind actual geared speed of engine. the air flow to keep the engine cool is easily produced by 2 15amp electric fans. say the driven fan is 2 times the air flow, still, we are talking 1hp input. even 4 x would still be less than 2hp . trust me , until you go to a dyno, its very low.


I can tell you that when i had my 1978 4 speed El Camino(powered by a 1972 350cid/370horse Vette LT-1 motor) that when i switched from the OEM clutch fan to an electric i got a full .2 second improvement in actual ET
>>>>>>>>>> so, .2 seconds. this means the fan is worth close to 20-30hp and you still have a draw on the alternator, you cant get something for nothing.
there are lots of stories like this. so many variables, its like Magic to disprove. but an old science like physics, can dispell many of the assumptions. a fan at a certain speed based on diameter and pitch of the blades is very easy to approximate its power consumption. ever see the fans they use on dynos, those things practically blow your car OVER!! they are less than 5hp. HARDLY enough to make a .2 second time diff in a 1/4mile. HOWEVER, it all adds up,and i removed mine and most racers do. Mosty for the weight.

mk

LOL... [/QUOTE]

mark kibort

He has already said it could be a stroker, and he said it has a gigantic AFM or MAF. (certainly not an 83 US afm) i would start there.

Mk

m21sniper

"Ill give you the cliff notes on gearing efficiency, and if you have any doubts, see your local physics teacher, race book , or read the 100posts on the topic a month or two ago."

I'm formally educated(associates equivelant from LTI in automotive and diesel technology, 3.8GPA), and spent 5 years as an automotive technician. I know what gear ratios do bro.

"gearing doesnt create hp and thats what you need for a quick 1/4 mile run."

HP really has squat to do with performance. Torque does.
HP is about the most useless and misleading figure in common use today(1 HP is the ability to lift 33,000lbs 1 foot in 1 minute, and is really a very innacurate derivative of a very useless formula created by James Watt to sell steam engines.). Performance is all about torque. A lower(numerically higher) gear ratio multiplies torque through mechanical means. That is simply a fact, and not subject to interpretation.

Performance enthusiasts always chat up HP, when in reality they should be chatting up torque. Torque is what matters. HP is really quite meaningless. The next time you look at a car with a really high HP rating, but it's ET seems slow....look at the torque, it's always lower than the HP rating. Comparatively, the next time you see a car with relatively low HP but with a surprisingly good ET(like the Buick GNs 13.9 @ 265hp), look at the torque. It's much higher than the HP.

"you want as many gears as possible in this range to keep the engine near max HP for as much of the time as possible. if you have a 3 gear or a two gear run to 103mph, you want the last gear to be near redline . EVEN if it means making a taller rear end. (numerically lower, i.e. 2.2 compared to 2.75)."

Now THAT i agree with, completely.

" there are trade offs. in fact, you mention going to a 4.5:1 rear end to make your last gear redline at 103mph. this would be fine if you could change the ratios of the gear box. with 4.5:1, you would have a 1st and 2nd that could basically be unusable (too low) and then the spacing for the next few gears could be the same as a stock car going to 2nd or 3rd depending on the cars were car comparing it too."

In a true 1/4 mile machine you want to use all your gears, and be very near max rpm in top gear at the traps. Any unused gears are in effect completely wasted in a 1/4 mile car. It is true that with 4.56 gearing my car would be a lot less 'streetable', but that does not change the fact that 4:1 and higher numerical ratios absolutely dominate at the 1/4 mile strip. A 2.20:1 final drive ratio is all wrong for a pure 1/4 mile car. In effect, i'm completely wasting 2 gears.

"in fact, a 2.2 compared to a 3.09:1 in an GTS 5 speed, gives a much shorter 1st, and then a taller 2nd compared to a S4 in 1st gear to the same realative speeds."

That's a function of the transmission gear ratios combined with the rear end ratio, not the actual ring and pinion of the transaxle alone. The difference in performance in gears between the two cars is a function of engine power and transmission/rear end gear ratio combined.

All things being equal(ie equal engine power and equal trans gearing), a car with a 2.2:1 rear end gearing will have much longer legs(ie much higher top speed) than one with a 3.09:1. The 3.09:1 will exhibit substantially better acceleration via torque multiplication, but at the cost of a significant amount of top end.

What you're discussing is combining trans gearing with known engine power to determine the absolute best ring and pinion ratio for a given performance need.

I agree with your assertions there, and i think we're mainly talking past one another.

My assertion is that a lower(numerically higher) final drive ratio will increase acceleration via torque multiplication at the cost of top end speed and economy with all other things being equal. That is a 100% factual statement, as i'm sure you'll agree.

The reason i specifically mentioned 4.56:1 is because that's approx. the level of gearing i'd need to reach max engine RPM in top gear at the end of a 1/4 mile, hence the overwhelming popularity of 4:1 and lower final drive ratios on 1/4 mile cars, and the reason our 928s-which are overwhelmingly geared toward top end performance- having much higher(numerically lower) final drive ratios.

If Ferdinand had 1/4 mile racing in mind when he designed the 928 he'd have ensured they had a MUCH lower(numerically higher) final drive ratio.

m21sniper

Normy, you can drive your lovely Euro off a cliff for all i care. It's a dog.

I already beat an 83 Euro with a 75hp shot of nitrous by 3 lengths, you quite frankly are not even in my shark's league. Take your slow car for a nice long ride to the cattle farm of your choice and stop trolling up an otherwise interesting discussion.

I have provided two witnesses that have verified my 928s performance level....you?
Because based on your stated mods your Euro should be nowhere near as fast as you claim. I guess that must make you a liar...by your own logic.

Apply your own skepticism to your own claims and go argue with yourself in front of a mirror for a couple hours.

PS: 106 is a REALLY high trap speed for a 13.86 run.
I simply DON'T believe YOU troll boy.

Lance J

I will do this one more time after racing sniper 3 times. 1st from a dig he put 3 cars on my 3 speed auto. 2nd time we did a roll start which i put sniper a my door. he was very kinda to tell me he would match my speed until my euro started to build power (@ 3krpm). last was highway runs which we never line up i just pass him to get sniper started and once he took the bait. i saw if he could keep up. my euro was to much for him up top. but down low is a different story. it seems to me that his car has a lot i mean a low of low end tq, also his gearing his different than heathers who also has an 83 stock 4 speed tranny. when he brake boost in the parking lot we meet at. his tires would spin b4 his tq convert would stall. he was spitting rubber at my car. now i knew my euro was only for topend. even with the nos my cams would not let me make power below my 3k rpm power burst. the nitrous help a tad bit to get the rpms up quicker to 3k. once i hit 3k the nos was usless. so i never shoot the nos above 3k. soory to tell ya sniper i never shoot above 3k. but its pretty sad that on the first run i shoot the nos until 4k for the first run but it took me 3 seconds to get there because my stall speed was low as hell (2100rpm thats sad)

m21sniper

"i dont care what the NADA published, ive made 4 928 race cars and they weight 3350, and after you gut the obvious, it gets down to 3050lbs (empty) give me what you removed and ill tell you what you weight."

I've posted what i removed on at least two different threads, including earlier in this thread.

As far as the actual curb weights, i can only go by the official figures(NADA being about as official as it gets), as i never weighed my car before i started(or after for that matter), but regardless, i'm fine with your 3350lb figure for the purposes of this discussion.

"Of the 4 cars i help build, all of them weighed 2700 to 2800lbs. (and everything in between up to 3450bs for my partially gutted to start S4)"

Based on your figure of 3350lbs mine is likely a bit 3000lbs.

"again, i did the headers on a 84, it was 12 rear wheel hp, with no cat. then, removing the cat bypass and replacing the entire stock muffler, it was another 12hp. 24hp for headers and straight through exhaust"

We also have to acknowledge that the same exact setup on a different day, or even the same day on a different dyno may very well have yielded significantly different figures(which is why i do not pray at the dyno altar), and we also must consider that the power that is gained from an exhaust change is dependent on other internal mods in the engine. My engine internals may very well be significantly different than those of the 84 you did. Further, even two identical production vehicles can yield varying results for the same exact modification due to production variances in engine tolerances. One car might make 12hp, just like yours. Another might only make 9, while a 3d vehicle might make 15.

"iive tested it, and you can easily calculate it."

I do not doubt that(or any of your claims), i would however re-state that any two cars can yield significantly different results for the same exact modifications. You said 1-2rwhp, i said 4-9. Given that my 4.7l is apparently at a significantly higher power level than yours was(or at least seemingly so), it is completely reasonable to expect that a 3% reduction(just as a for instance) reduction in parasitic loss on mine would result in more actual power gain than the same 3% reduction in yours.

Regardless, i've seen the removal of power driven accesories produce excellent real world results based on timeslips(now it's possible the .2 improvement in my El was a result of me launching better, or better atmospheric conditions, or whatever- but whatever the case, that day i was a consistent .2 quicker, and that was the only change i'd made subsequent my previous trip to the strip), and while we may disagree to a small degree about the power gain, we both seem to agree that the power gain is there(which puts us both on very solid ground from a physics standpoint, lol).

There is also other factors at play, such as rotational mass and atmospheric drag. You have to accelerate that fan blade, and the pulleys, and the internal shaft of the accesory itself(and in an A/C compresser the pistons and crankshaft) Doing so wastes energy that would otherwise be applied to the flywheel. Once it is accelerated you have to continue to turn that accesory in the face of atmospheric resistance, which also requires power.

Thermodynamic heating loss also comes into play somewhere in all of this, but thermodynamic theory is well outside of my area of practical knowledge, so i won't even begin to try to argue it.

At any rate, the three accessories i removed were Clutch fan, Air pump, and A/C.

mark kibort

Yes, because you have agreed with the key concepts, i wont push it.
BUT, if you really look into hp vs torque discussions, its really all about HP.
torque is as meaningless as RPMs if you dont tie them together. HP is torque x speed! so, whats nice about HP, is most of the math is done for you.

great example of this is two cars, both 500hp. one makes max HP at 5000rpm and has a peak torque of 500lbs vs another makes it at 10,000rpm and its max torque is only 250ftlbs .

which car is faster assuming all other things being equal. answer this and you get the point. Ill answer it for you. both will be identical in most every way as far as acceleration. this kind of disproves the torque is everything DEAL that you hear about on tv all the time, especially in SPEED GT where they alwasy talk about those big 6 liter C5R vet powered vets and caddies , having the big "grunt" and "torque" off the turn, and yet the little 1/2 the torque 911s seem to stick right with them! (even when close to the same weights. i.e henzler last season was carrying 200lbs on his base weight making him real close to many of the vets as far as weight. Hp on the 911 is close to 450. hp on the vets is close to 550. However, remember the close ratio gearing advantage, which turns that 450hp really into more like 500hp on the vet. this makes sense as they drag raced all race long neck and neck. (remember, the porsche only has 280ftlbs of torque too! BUT, at 9,000rpms!!!!)

so you see , torque is really the meaningless number, unless you tie an RPM to it. this is just plain simple physics. something i taught in classes many years ago. (applications of power transmission devices for industrial controls)

Matching of HP to torque is fairly arbitrary. it really depends on the torque units you are using (ie ftlbs, oz in, N, Kcm, etc) but i understand your point, and it still has no meaning as it really depends on the shape of the HP curve (ie torque curve over speed) and how the gears utilize the HP over the speed range.

Want more proof, if you had as many gears as you could want. (ie, infinitely variable, or in otherwords millions of gear ratios in one box) where would the engine end up as far as speed on a drag launch, max torque, or max HP??????? now, get this right and you understand. get it wrong, and you may want to consult with one of your ASE tech teachers!

Well, i think you and everyone knows the answer, any engine with lots of gears wants to have the engine rpms as close to max HP (NOT TORQUE) as possible.
To the term's credit "torque" to the wheels will always be higher at max HP at any speed through a gear box. make sense.

MK