Rear Wheel Horsepower
10-04-2013, 07:12 PM
#1
Safety Car
Thread Starter
Rear Wheel Horsepower
Presented for your perusal:
In tonight's episode, we peer at a 327 engine that is apparently delusional on the Gyromometer. It has been "genetically altered" from its sense and form when the creator put it on this planet.
In the course of its work, it showed 382 horsepower at the rear wheels, although the line was "squiggly" after 4000 RPM. This mysterious energy happened gradually, and reached it's total destructiveness at 6700 RPM. The spark timing, or "life force" was not nearly as advanced as it should have been, at only 28 degrees at its limit. And the life-blood, that the monster was drinking, was wanting, at a frighteningly crispy 13.2:1 at 7500 RPM, when the monster was commanded to die.
What does that translate to, in the human way of communicating as, Gross Horsepower, I believe?
What should the peak destruction, or horsepower, be if the beast was given more plutonium, known to earthlings as octane, and the feed of octane was increased to a more desirable rate, like 12.8:1 at 7500 and, most importantly, the life force, or spark timing, was further advanced to a more beastly value like 36 degrees.
The car: a Corvette. The Transmission: a Ford T45 in 4th gear, 1:1 driving 3.70 rear axle.
Tonight's case in point in...............the Highlight Bone.
In tonight's episode, we peer at a 327 engine that is apparently delusional on the Gyromometer. It has been "genetically altered" from its sense and form when the creator put it on this planet.
In the course of its work, it showed 382 horsepower at the rear wheels, although the line was "squiggly" after 4000 RPM. This mysterious energy happened gradually, and reached it's total destructiveness at 6700 RPM. The spark timing, or "life force" was not nearly as advanced as it should have been, at only 28 degrees at its limit. And the life-blood, that the monster was drinking, was wanting, at a frighteningly crispy 13.2:1 at 7500 RPM, when the monster was commanded to die.
What does that translate to, in the human way of communicating as, Gross Horsepower, I believe?
What should the peak destruction, or horsepower, be if the beast was given more plutonium, known to earthlings as octane, and the feed of octane was increased to a more desirable rate, like 12.8:1 at 7500 and, most importantly, the life force, or spark timing, was further advanced to a more beastly value like 36 degrees.
The car: a Corvette. The Transmission: a Ford T45 in 4th gear, 1:1 driving 3.70 rear axle.
Tonight's case in point in...............the Highlight Bone.
Last edited by 65tripleblack; 10-04-2013 at 07:17 PM.
10-04-2013, 10:48 PM
#4
Le Mans Master
Nice Dyno Run Triple Black, you have been working on that a long time. Congratulations.
It would be great to see the curve, I would like to see where the HP and Torque kick in.
Why so conservative on the timing? Bad gas? It must be very close to the desired number to make that power. Maybe your head design is close the the Vortec design.
The Vortec design usually runs best at 28 or so.
And 25MPG on the HWY with your new overdrive???
It would be great to see the curve, I would like to see where the HP and Torque kick in.
Why so conservative on the timing? Bad gas? It must be very close to the desired number to make that power. Maybe your head design is close the the Vortec design.
The Vortec design usually runs best at 28 or so.
And 25MPG on the HWY with your new overdrive???
10-05-2013, 02:57 AM
#6
Melting Slicks
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More like 450hp if we use 15% loss which is more typical/realistic, but still a nice number. What's the combo? What did you get for peak torque and at what rpm?
10-05-2013, 08:33 AM
#7
Melting Slicks
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Joe, good numbers on your little 327, there is probably a few more with some tweaking. I am in Ocean City right now on the 8th floor of my hotel over looking the ocean. Corvettes are every where. I saw at least 10 C2's yesterday. Next year I am bringing mine. We are leaving in a few minutes for the car show. Wow, it is a great time, wish you were here.
10-05-2013, 12:10 PM
#8
Safety Car
Thread Starter
Thank you all for the kind words.
Yes, it was very gratifying and pleasing, and frankly, I did not expect those numbers.
Weslotorn (Mark): The reason for the retarded timing, is because my 35 YO Sears timing light does not agree with TWO timing lights used at the dyno shop. I remember that the addition of the MSD box affected the timing reading, which left me scratching my head at the time. The timing light situation now explains that! The dyno operator eyeballed the plug electrodes with a loupe and told me the burn marks on the electrode did not indicate what I thought the timing was.................20 initial plus 17 centrifugal. Sure enough, I measured it using both his lights, at 12 plus 17 or about 29 degrees at WOT. The a/f ratio confirms my own testing, which starts off fat and goes too lean after about 6000 RPM.
I will fix the timing after I get a new light, and then fiddle with the secondary main air bleeds to get the mixture more linear. I was wishing for 400 RWHP, and it looks like I should get that, and more once I get it dialed in.
The dyno shop owes me the .drf (runfile), and once I get it, I'll post up the 3 pulls.
Donny: I don't understand your post? I click on the link that says "click the image to open to full size", but the link doesn't open. What are you trying to show me/us? I wish you could drive my car down the 1/4. I'll bet you'd be in the low 12's with it.
Yes, it was very gratifying and pleasing, and frankly, I did not expect those numbers.
Weslotorn (Mark): The reason for the retarded timing, is because my 35 YO Sears timing light does not agree with TWO timing lights used at the dyno shop. I remember that the addition of the MSD box affected the timing reading, which left me scratching my head at the time. The timing light situation now explains that! The dyno operator eyeballed the plug electrodes with a loupe and told me the burn marks on the electrode did not indicate what I thought the timing was.................20 initial plus 17 centrifugal. Sure enough, I measured it using both his lights, at 12 plus 17 or about 29 degrees at WOT. The a/f ratio confirms my own testing, which starts off fat and goes too lean after about 6000 RPM.
I will fix the timing after I get a new light, and then fiddle with the secondary main air bleeds to get the mixture more linear. I was wishing for 400 RWHP, and it looks like I should get that, and more once I get it dialed in.
The dyno shop owes me the .drf (runfile), and once I get it, I'll post up the 3 pulls.
Donny: I don't understand your post? I click on the link that says "click the image to open to full size", but the link doesn't open. What are you trying to show me/us? I wish you could drive my car down the 1/4. I'll bet you'd be in the low 12's with it.
Last edited by 65tripleblack; 10-05-2013 at 12:21 PM.
10-05-2013, 12:31 PM
#9
Safety Car
Thread Starter
Joe, good numbers on your little 327, there is probably a few more with some tweaking. I am in Ocean City right now on the 8th floor of my hotel over looking the ocean. Corvettes are every where. I saw at least 10 C2's yesterday. Next year I am bringing mine. We are leaving in a few minutes for the car show. Wow, it is a great time, wish you were here.
I'm happy to hear that you're there. Not feeling well the last 5 days, so decided to stay home for this one. I got snagged as an NCRS judge next weekend, so won't make the Endless Summer cruise next weekend, either. Besides, it was sold out long ago. You must have been to the ES cruise before. The event outdoors looks like fun, as well as the parades. I'm definitely going to pre register for next year's outdoor cruise. It would be good to see you and your beautiful C2 there! Did you straighten out things with the C6?
uxojerry and 68sixspeed: just a very carefully built (.030 over) 327 (331). internally beefed up Crower connecting rods bought in a group deal with Scott Marzahl. 205cc aluminum heads with heart shaped 64cc chambers. 11.3:1 static compression, 1 5/8 inch sidepipe headers, solid roller cam 1.6 rockers 255/250 @ .050 .605/.610, 780 DP Quick Fuel with ported LT1 dual plane.
10-05-2013, 12:42 PM
#10
Race Director
I was just using 20% last night that's all. You are right though if you use 15% its closer to 450 HP either way pretty impressive
10-05-2013, 02:19 PM
#12
Safety Car
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Joe, it's just 'bow down smileys'... not sure why you can't see them
congrats on the huge HP number, that is way cool
congrats on the huge HP number, that is way cool
10-05-2013, 08:40 PM
#13
Safety Car
Thread Starter
You can blast off with my car anytime.
Last edited by 65tripleblack; 10-06-2013 at 11:22 AM.
10-07-2013, 08:52 AM
#16
Safety Car
Thread Starter
Mike Green's heads.
Chad Speier, of Speier Racing Heads is Mike's go-to guy in porting his heads. Chad is a nice guy, but he has some days when his work is not up to par. Either he's erratic, or he has an assistant do certain things, which are not checked before shipping work out the door.
Chad Speier, of Speier Racing Heads is Mike's go-to guy in porting his heads. Chad is a nice guy, but he has some days when his work is not up to par. Either he's erratic, or he has an assistant do certain things, which are not checked before shipping work out the door.
Last edited by 65tripleblack; 10-07-2013 at 10:19 AM. Reason: wrong name: Mike to Chad sentence 3
10-07-2013, 09:35 AM
#17
Safety Car
Those are great numbers for RWHP!
It may surprise you to find out that for the younger crowd driving late model Mustangs modded to the hilt and tuned by laptop computer, HP at the flywheel is largely ignored. Most of em have no idea what the motor makes, because the cars for the most part are set up and tuned on a chassis dyno, just like yours was. I can say the same for my '03 Cobra. I know what it makes at the wheels, but the flywheel number, who knows, and who cares? In fact, RWHP is really the only relevant number; flywheel HP doesn't make the car go fast, it's what gets transmitted to the tires that does.
The rules of thumb commonly used are 10% drivetrain loss for a manual trans and 15% for an automatic, if the flywheel HP number is important to you. The old SAE gross HP number was for a motor on a dyno with NO accessories being driven and a free flowing exhaust. SAE net (which started being used in in the early '70s, is with the motor configured as installed in the car (driving all accessories and with the exhaust system used in the car).
FWIW, you may not even need 36 degrees total advance. Newer heads have much better designed combustion chambers and make full power at much lower timing advance than the antiques.
It may surprise you to find out that for the younger crowd driving late model Mustangs modded to the hilt and tuned by laptop computer, HP at the flywheel is largely ignored. Most of em have no idea what the motor makes, because the cars for the most part are set up and tuned on a chassis dyno, just like yours was. I can say the same for my '03 Cobra. I know what it makes at the wheels, but the flywheel number, who knows, and who cares? In fact, RWHP is really the only relevant number; flywheel HP doesn't make the car go fast, it's what gets transmitted to the tires that does.
The rules of thumb commonly used are 10% drivetrain loss for a manual trans and 15% for an automatic, if the flywheel HP number is important to you. The old SAE gross HP number was for a motor on a dyno with NO accessories being driven and a free flowing exhaust. SAE net (which started being used in in the early '70s, is with the motor configured as installed in the car (driving all accessories and with the exhaust system used in the car).
FWIW, you may not even need 36 degrees total advance. Newer heads have much better designed combustion chambers and make full power at much lower timing advance than the antiques.
10-07-2013, 10:33 AM
#18
Safety Car
Thread Starter
Those are great numbers for RWHP!
It may surprise you to find out that for the younger crowd driving late model Mustangs modded to the hilt and tuned by laptop computer, HP at the flywheel is largely ignored. Most of em have no idea what the motor makes, because the cars for the most part are set up and tuned on a chassis dyno, just like yours was. I can say the same for my '03 Cobra. I know what it makes at the wheels, but the flywheel number, who knows, and who cares? In fact, RWHP is really the only relevant number; flywheel HP doesn't make the car go fast, it's what gets transmitted to the tires that does.
The rules of thumb commonly used are 10% drivetrain loss for a manual trans and 15% for an automatic, if the flywheel HP number is important to you. The old SAE gross HP number was for a motor on a dyno with NO accessories being driven and a free flowing exhaust. SAE net (which started being used in in the early '70s, is with the motor configured as installed in the car (driving all accessories and with the exhaust system used in the car).
FWIW, you may not even need 36 degrees total advance. Newer heads have much better designed combustion chambers and make full power at much lower timing advance than the antiques.
It may surprise you to find out that for the younger crowd driving late model Mustangs modded to the hilt and tuned by laptop computer, HP at the flywheel is largely ignored. Most of em have no idea what the motor makes, because the cars for the most part are set up and tuned on a chassis dyno, just like yours was. I can say the same for my '03 Cobra. I know what it makes at the wheels, but the flywheel number, who knows, and who cares? In fact, RWHP is really the only relevant number; flywheel HP doesn't make the car go fast, it's what gets transmitted to the tires that does.
The rules of thumb commonly used are 10% drivetrain loss for a manual trans and 15% for an automatic, if the flywheel HP number is important to you. The old SAE gross HP number was for a motor on a dyno with NO accessories being driven and a free flowing exhaust. SAE net (which started being used in in the early '70s, is with the motor configured as installed in the car (driving all accessories and with the exhaust system used in the car).
FWIW, you may not even need 36 degrees total advance. Newer heads have much better designed combustion chambers and make full power at much lower timing advance than the antiques.
Thanks. I was flabbergasted when I learned that my timing light has been lying to me. I understand that heart shaped chambers are more efficient, but they are not "compact" at 64 cc, and the pistons are domed, which supposedly slows down the flame front. A compact 58 cc chamber with flat tops will probably show optimal timing at 29 degrees, like mine was ( tricked into being) set at. I figure that this engine should be optimized at about 34 degrees, rather than the 36-38 that the antique heads like. So, I have to add another 4-5 degrees advance. The mixture is a bit too lean after 5000 RPM, and I'll fix that with air bleeds. My goal was 400 RWHP, and I think I'll be there after the timing and mixture are tweaked.
400 RWHP translates to (appx) 450 SAE net flywheel. I'll assume that the air filter, which was in place for the pulls, and the water pump, pulleys, and fan might be worth about 10 gross HP at 6750 RPM. So, translated to pre 1972 numbers, this thing puts out around 460 gross HP @ 6750.
I'm going to try and get the .drf files from the dyno operator today. If I'm successful, I'll post up the graph. I can also compare this config to the old config: same engine with double hump heads. We did that comparison at the dyno shop, and the results were stunning. More torque right from the bottom to the top end! I did NOT expect to see that.
Last edited by 65tripleblack; 10-07-2013 at 10:36 AM.
10-07-2013, 12:16 PM
#19
Le Mans Master
I too have an old Set Back Timing light from the Sears offering. I did note it seemed to freak out when I tried to use it on a MSD equipped car.
What is the answer when timing a MSD system. I like it and trust it when not working with MSD systems.
What is the answer when timing a MSD system. I like it and trust it when not working with MSD systems.
