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Here's what 433 RWHP does on the 1/4 mile

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#101 ·
I am talking with Larry now.
Yes he has stated flywheel and also states the "Peak HP" is calculated from ordinary
"Physics concept of POWER = FORCE x VELOCITY"

That's all well and good but apply that to a jet car or speeding bullet or something that has no flywheel. Where do the flywheel numbers fit in then?

I'm not trying to be a pain in the butt, but the above statement; "POWER = FORCE x VELOCITY" working with flywheel numbers, then minus drivetrain losses just doesn't gel with me. How can they?
It's like money in the bank then minus the taxes = how much you really have to spend. -That's the figure you're dealing with.
I want calculated results, not just take somebody's word for it.
 
#102 ·
Well, if you dont believe Larry them who can you trust... he's a good christian guy,
dont think hes pullin your leg, plus he's smarter then all of us put together;)

Think of this, back in the 60s they needed to know what their "new engines" would
run in their well set up stocker cars. So what did they do? Pulled out some hemis
and 413 wedge motors out of cars that ran 11s / 10s and dynoed the motors, from this
(lets say they found out that car X ran 122mph, at 3500lbs, and engine made 500hp)
they knew how much power it took to accelerate a weight to a certain speed at a given
distance, and from that made the HP formula, it was from real world testing and results.
This is where HP=(mph / 234)cubed x wt. comes from.

On the drivetrain losses they figured out that there was a slight difference in mph between
the automatic and stick cars. And yes drivetrain losses will very from car to car depending
on set ups, but they know that on average in a well set up car X hp will run X.
 
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#104 ·
Steve,

Desktop Dyno predicts 574 HP at 6000 RPM and 570 lb-ft of TQ at 4500 RPM for your engine combo. Again, DD2k is widely known to be optimistic.

Using this exact engine combo -- when I import it into Desktop Drag it predicts a 11.00 @ 124 MPH for your car with 95* heat and 60% humidity. Your car still lags significantly behind even the 574 flywheel HP predicted with only a 122 MPH trap speed. With less than 574 HP at the flywheel there is no way you are at 521 at the rear wheels.

Steve, the first link you provided matches my combo much closer than the second. The AFR 195 heads in the first example flow close to my TFS heads. The 2nd uses a bigger 406" engine and AFR 215 heads. I don't think that the cams make a significant difference in power output -- ask Rafel about the power he makes with a little HR cam and good heads. The intake does not make a big difference either -- I have tested both manifolds on my engine with the Vic Jr being only marginally faster (like .05) than the RPM air gap (there was significant debate on this very test and fairly inconclusive results so try a search if you want to read up).

I also think that the power output of the engines advertised in these ads are a little exaggerated. Advertisements by engine sellers are clearly less reliable than two separate independent chassis dynos I have had my car on. You are reaching to compare my dyno tests to advertisements. There have been many threads here about buying an engine off the net, getting it in the car, and seeing it underperform.

On the other hand, GM is known to under-rate their crate engines and they look weak compared to other manufacturers. They do this so buyers are pleasantly suprised when they buy a crate engine. This has been documented in several recent mag tests of the ZZ-572 crate engine.

At this point, if you can't see the reality of what so many of us are saying then you don't want to see it and there isn't anything that I can say to convince you otherwise . . .

Good luck
 
#105 ·
Well, I think I see the issue(at least part of it). Lets ignore horsepower for just a minute all together cause we arent getting too far on that. I definitely think its that glide tranny thats skewing your cars results. Youve only got a 3500 converter with 4.11 gears and your trying to run it up against a glide. Thats why it doesnt have the punch that it should. Your effective gear ratio is the same as a 350 turbo with right around 2.73 rear gears, and although big blocks can work with those kinda gears.....your still asking a lot from the engine when its in that sorta situation.

Changing nothing else but the tranny to a turbo 350 and a purpose built converter would show good results over what youve got. Your engine sounds more like a real strong street combo and the glide doesnt jive with that basically cause of the location of the powerband. This is at least one reason why your car with all that RWHP doesnt run the number that other cars with less do. Glides like a lot more head, a lot more converter, more gear, and more cam. You ought to be launching at 4500rpm or so with a 4.30 gear minimum and a 260+ degree cam and better heads(or work to the current ones)...running to about 7200rpm or better for that glide to be useful. Right now its slowing you down.

With the new roller, if its a lot larger it might not help matters if everything else stays the same. If your just moving up the powerband with that new cam but keeping the gears and converter, the first half of the track might go by that much slower. If it indeed does provide a fair amount more peak horsepower Id figure on a higher mile per hour, but the ET's wont improve as much as they should. Youd need to follow up with at least a converter and gearing......and headwork isnt a bad idea at all cause its gonna need to be able to breathe at the higher rpm with more gear. Or, you might want to consider a tranny change depending.
 
#106 · (Edited)
Hey John, Here is one time slip (run #8) and page 1 of 3 for that day.
These runs were at Calder Park raceway. I never recorded the weather on that day. I remember it would have been about mids 20sC/77F and sunny. The elevation is 200ft above sea level.


As you can see, the 60fts are crap! For 121-2mph they are probably off by maybe 3 tenths or more.

Greg will note that I wrote "needs more launch rpm". That is true. (I wrote that afterwards.. all on that page were 2000rpm) I will be increasing the rpm to 4000 from 3500. I know that it will love 4500 but it is still a street car and the extra 500rpm I'll do without (for now). I'll see what I can get away with.
A TH400 may have been a better way to go but when I plugged in the TH400 into DeskTop Dragstrip, I remember it telling me I was going to be maybe 0.15 secs better off than the 'Glide. It wasn't worth the money, the weight, and more drag to swap. Did the program calculate more losses with the TH400 over the 'Glide???
4.11s work with the rpm, tire height and mph the car is running.
 
#107 ·
You guys must know where I am coming from with this flywheel/rearwheel thing. I bet there are people reading this and plugging numbers from my examples and watching them add up.

I know what Larry has said (so far) but there is still a discrepency about Power = Force x Velocity.
Power = the total force acting on the object.
-not Power = Force from somewhere within it, minus an unknown, unspecific amount x Velocity.

OK so maybe HP = (mph/234)3 X weight is at the flywheel.
They don't work with my 396/375 example (post #69), the Holden Monaro example (#81), Luccamaro's 496 vs Edelbrock 540hp engine (#53), the GMPP350/308hp example (GM do not under-rate crate engines that they want to sell, -let alone by up to 25%! I have seen a 502/502 make 505hp corrected.) (#96) and it certainly doesn't work with any aspects of my example either. It's funny how they all do work with rear wheel numbers though.
Another example I just found in http://www.rehermorrison.com/ 's site. Click on the super series 412 link and read how 675HP pushes a 1650lb dragster to 163mph. Only 163mph? Why not 174mph like the slide rule says based on flywheel numbers? Seems to work perfectly with conservative rearwheel numbers though.
These and other examples are why I am staying put with my view. :clonk:

Eric, I also doubt whether the HP ratings are that far off on those links I posted you, but OK. I'm surprised you are so content on your very healthy small block putting out just 1.3hp/ci. Your cam, heads and compression equal more cylinder pressure than that. And I bet your RPM is low to mid 7s.

Anyway, although this debate is a little frustrating, I'm having fun with it and hope we are all still friends (even though you're all wrong!! -Just kidding.. sort of.. hehe :beers: )
 
#108 · (Edited)
BlackoutSteve said:
I'm surprised you are so content on your very healthy small block putting out just 1.3hp/ci. Your cam, heads and compression equal more cylinder pressure than that. And I bet your RPM is low to mid 7s.
Click to expand...
You shouldn't be suprised Steve, it doesn't matter at the stripe if my car is 399 RWHP or 521 RWHP. My goal is not an HP number, it is an ET and at least a bumper lead on the other guy at the stripe.

On the RPMs Steve, I hit the shifter at 6400 and the car is in the next gear by 6600 (maybe 6800 on the 1-2 shift if I'm slow). No way do I go to mid 7000's . . . I run with a 7k chip.

How do you explain two different chassis dyno's that have put my engine at 365 RWHP when I was running an 11.9 ET (before roller cam) and 399 RWHP with an 11.2 ET ?

and how come 2 different brand chassis dynos in two different parts of the State of Michigan seem to agree with each other?
 
#109 ·
OK so maybe HP = (mph/234)3 X weight is at the flywheel

Now youre talkin!

They don't work with my 396/375 example (post #69), the Holden Monaro example (#81),

Thats because the HP formula is for a "well setup" race car, which a lot of street cars aint, and have
a hard time running. And stock, showroom cars with exhaust manifolds and bicycle tire,
inefficient air filters and so on... cant run.

It's funny how they all do work with rear wheel numbers though.

How do you figure? we've given you tons of examples that work with flywheel hp...
Mine, friends, stockers - wchich some of surpass the HP formula because of their
efficient drivetrains and attention to detail, tunning and constant track testing.

Anyway, although this debate is a little frustrating, I'm having fun with it and hope we are all still friends even though you're all wrong!!

Friends... where's my shotgun;)
 
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#110 ·
"How do you explain two different chassis dyno's that have put my engine at 365 RWHP when I was running an 11.9 ET (before roller cam) and 399 RWHP with an 11.2 ET ?

and how come 2 different brand chassis dynos in two different parts of the State of Michigan seem to agree with each other?"

Exactly Eric.. Me too. I have the same experience, different dynos, different drag strips, same results.
 
#111 ·
Hope yall dont mind if I chime in with a Question. I seems to fit in with this thread.

Are the chassis dynos and slide rules giving Peak horse power numbers? And if so, If you had 2 engines with the same peak HP, but one had quite a bit more total average HP through out the power curve. Wouldnt the engine with more average HP run a quicker ET. Couldnt that explain why compairable cars with the same measured HP can run different ETs ?

The reason I ask, is that I'm concidering a change with my 505 engine combo.
I have just finished building up a set of 049 ovals to try on this engine. They are fitted with 2.19/1.88 valves, full bowl port and some work around the guides, polished chambers and port matched to a Victor Jr.
The heads I have on it now are the old school GM aluminum [] port 074s. Just a little bowl blend. I'm also using a Victor jr with these heads.

Both sets of heads peak flow 300 to 305 cfm at .650 lift with the ovals flowing slightly better than the [] ports at lower lifts.

cam is hyd roller .244/.256 .632 lift, 10.5 compression , 950DP carb. Car runs 11.50 at 119 MPH now with .373 gears, TH 400, 3000 stall throught the mufflers and shift at 6000 rpm. elevation 3000 ft.

Do you guys thing the car will ET quicker if I change heads to the 049s??? Nothing else will change on the car except the heads.

Since both sets of heads have the same peak flow numbers, I would assume the peak HP would be the same. But the better low lift flow and higher velocity of the flow in the oval heads should make more AVERAGE HP through out the power curve. And thus quicker ETs ???? Which brings me back to the question I asked in the begining of this post.

Thanks for any input. Scott
 
#112 · (Edited)
67RS502. "They don't work with my 396/375 example (post #69), the Holden Monaro example (#81),

Thats because the HP formula is for a "well setup" race car, which a lot of street cars aint, and have
a hard time running. And stock, showroom cars with exhaust manifolds and bicycle tire,
inefficient air filters and so on... cant run"

The Holden Monaro and any car after somewhere in the early 70's have SAE net horsepower ratings in accordance with SAE J1349 which stipulates that all engine accessories, OE air filters and as-installed exhaust systems are fitted to the engine as would be installed in the vehicle when the flywheel HP numbers are recorded.
Therefore the Monaro with it's 225KW/302HP designation is net flywheel hp before it enters the drivetrain.
This Monaro has an ET of 14.7 @ roughly 88-90mph in stock form. This clearly shows hp to be around 164KW/220HP on the slide rule which is right in line with assumed drive train losses.
As Eric and I both know, the mph will change very little with improved gearing in this example. The slide rule and formula suggest an unbelievable 101mph if flywheel numbers were assumed for this car.

"It's funny how they all do work with rear wheel numbers though.

How do you figure? we've given you tons of examples that work with flywheel hp...."

The 396/375 Camaro never ran anywhere near 111mph suggesting 375hp at the wheels. That doesn't figure.
The ZL1 did run 122.15mph with open headers. This would assume a lame 495fwhp, when the Penske Z28 crossrams were making 467fwhp with 302ci at similar rpms. That doesn't figure.
Reher Morrison's claim of 412/675fwhp in a 1650lb dragster running only 163mph. That does figure when as rearwheel numbers.
Luccamaro's 10.25:1 496 making the same hp/ci than Edlebock's 9.5:1 454. That doesn't figure.
My 12:1 454 making 4hp less than HotRod magazine's test 9.3:1 454/525fwhp which has a smaller cam and dual plane?? That doesn't figure.
The GMPP350/308hp running 98mph in 4200lb (yeah -right) '87 Goodwrench Camaro.. That doesn't figure.
Eric's 11.3:1 388/507fwhp making less hp/ci as http://www.strokerengine.com/sec383500HP.html 's 10.5:1 383/514fwhp that has 12 degrees @ 0.050" less cam a hyd instead of a solid and a dual plane. That doesn't figure.
Shall I continue?
Get the slide rule out or your calculator and you will see how all of these examples become very plausible when rearwheel/weight shifted hp is assumed.
All of the above is inconsistant crappola when using flywheel numbers.
That is how I figure. :)
 
#113 ·
damn drag this thread out, ladies.......

all i know is, i have seen an LS1 fbody go 10.55 with a 115 trap speed........ that sucker launched,,,,,think it had a super yank 4500 converter in it, on slicks of course, steep gears as well..................

my 93z went 11.37 at 121.57 with a race weight of 3550..... estimated around 475hp at the wheels in my calculations......my car stalled at 4k, shifted at 6100 and had 3.23's gears in it......stock suspension

all i know is EVERY CAR is different along with EVERY TRACK and dynos are different as well......., and NO calculation is going to be dead nutz on.........typically in the ballpark is as good as it gets...IMO.....

hope you gentlemen get this difference of opinion cleared up soon..........
 
#114 ·
Steve,

As stated above many times the formula is for FLYWHEEL HP. There a couple of key points to consider that keep getting missed.

Keep in mind that the track timing systems give you an AVERAGE velocity (MPH) over the last 66' . Your actual instaneousvelocity at the 1320 stripe will be faster. This is what the old formula was based on. If you compare the HP from the ET formula to the MPH formula you will notice that the MPH will yield lower results even for cars that are well sorted. Again, this is due to how MPH is measured at the track vs. instaneous velocity.

To correct the average MPH to instaneous, multiply your timeslip MPH * 1.0072. Then plug that value into the formula. This will give you the UNCORRECTED FLYWHEEL HP for the track conditions you are running in. Engine dyno as well as chassis dyno numbers are usually CORRECTED to standard conditions.

In addition to that, automatics do indeed use more power than standard transmissions. I believe the formula was derived for standard transmissions. I've found you need to add about 35-50 HP to the numbers that come out of the formula for automatic equipped cars.

Again, those are UNCORRECTED HP numbers for the conditions on the given day at the track. So more adjustment is required for weather conditions.

As you can see, lots of room for error and inconsistencies. That's why we race cars at the track and not dynos. :)
 
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#115 ·
DragRacer said:
That's why we race cars at the track and not dynos. :)
Click to expand...
or ON PAPER

out of all of the last 8 pages,,,,,,,,,,this is the only quote that matters to me.......... focus gentlemen...FOCUS
 
#116 ·
Thanks Kristofer.
I do have paper, dyno and track results that all agree with each other.
In fact, the paper and dyno accurately predicted the track results before I even got there! :)

DragRacer, Yes I am aware of the 1.0072 factor that compensates for the last 66'.
That is not even 1%.
In otherwords, it's not even worth mentioning (no offense).
The differences between flywheel and rearwheel being debated here are anywhere from 15-30%.
 
#117 ·
There's more there than just the 1.0072 factor. Read again.

In addition to that, automatics do indeed use more power than standard transmissions. I believe the formula was derived for standard transmissions. I've found you need to add about 35-50 HP to the numbers that come out of the formula for automatic equipped cars.

Again, those are UNCORRECTED HP numbers for the conditions on the given day at the track. So more adjustment is required for weather conditions.
Click to expand...
 
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#118 ·
Yes, I do understand what you have said there. Thanks.
Adding 35-50hp more for autos may sound more plausible, but I still believe the results are post transmission and axle regardless of the particular components installed.
I believe this because the difference between assumed flywheel and rearwheel numbers in the formula or slide rule are a good 100hp apart in most cases.
It just doesn't make sence to write a formula based on a particular power amount minus an unknown amount for drivetrain losses that vary for each and every individual application.
 
#119 ·
Scott, your 505, should run better with the ported 049s if both the rect. and oval
ports flow around 300cfm because the 049s will have higher velocity in the port
to flow the same 300cfm. On the other hand if the rect. ports are lighter theres
some speed to be had there. Or you could spend your $$$ in porting the 074s
to flow mid 300s to get the port speed up and they should work well also.
I see youre at 10.5:1 comp. if you stick the 049s on that will cause problems
on pump gas, so open up the chambers by unshrouding the valves, which will
pick up flow also. Yes the 049s will make power earlier in the power band, both
hp and tq.

Also your question about average hp - my Luv is a good example of how not
to set up a car, because it sees very little average hp while going down the track,
because its out of its power band for 1/2 the pass, because of its gearing and lack
of stall, big heads, and block huggers. So it sees a very low average hp while
going down the track. Off the line I'm waiting for the tach to go up from 2500rpm
to 4000rpm for this thing to start moving, its like a 6 banger, but the real power
band is 4500-6500.
 
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#120 · (Edited)
BlackoutSteve said:
"How do you explain two different chassis dyno's that have put my engine at 365 RWHP when I was running an 11.9 ET (before roller cam) and 399 RWHP with an 11.2 ET ?

and how come 2 different brand chassis dynos in two different parts of the State of Michigan seem to agree with each other?"

Exactly Eric.. Me too. I have the same experience, different dynos, different drag strips, same results.
Click to expand...
You aren't answering my question. How do explain that two different dynos here are telling me the same thing?

There are literally hundreds of people here in Michigan that have made chassis dyno pulls on these dynos and all seem to be in line with the power levels I claim.

Another example . . . my friends 327 with 142 blower made 360 RWHP on the chasiss dyno (a different dyno yet from the two I've been on) and runs 11.8's at 112 MPH in the quarter mile. Seems consistent with what I've been saying . . .

As for your dyno pulls, I'm sorry but there is something wrong with the dyno data you provided that I just can't quite put my finger on exactly what. For one, the TQ curve they gave you is not in the same format that I am used to seeing. It has total measured at the rear wheels and that 4.4 factor you use to estimate seems to be not quite right. Sorry, can't put my finger on what is wrong exactly, but your dyno results seem strange.

Maybe the answer lies with the theory that you guys run chassis dynos differently down there . . .

EDIT:

I think I figured what is worng with your dyno data. Going back to page 4 where you post you dyno sheet you explain that the measured TQ at the rear wheels is divided by 4.4 to get TQ. The TQ is estimated by dividing by axle ratio and factored for an estimated 7% allowance for converter slip. This allowance for converter slip results in actually correcting for drivetrain losses. Your drivetrain losses (or at least most of them) are ALREADY BAKED IN THE NUMBERS YOU REPRESENTED AS REAR WHEEL HP.

Your "chassis" dyno is ROUGHLY estimating FLYWHEEL HP but is not considering frictional losses in addition to converter slip. The reality of the matter is that your flywheel HP is probably closer to 550 (if you back out a couple percent for frictional losses) and your rear wheel HP is probably down closer to the low 400's that Luccocamaro's engine is running.

If you were to change your converter and rear gears to work well with the glide (or better yet, switch to a 3 speed and 4500 converter) your ET's would drop to high 10's and your MPH would probably increase to the 124 MPH that Desktop Drag predicts.

I think that Moroso slide rule is messing with your brain . . . my advise -- JUNK IT ;)
 
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