Back from the dyno - VIDEO ADDED
10-18-2010, 04:21 PM
#61
Rennlist Member
True point Ted, that gearing is absolutely relevant to the equation and identifying what the usable rpm range really is (at WOT).
something to consider that I mentioned before is that your situation is much more favorable, having headroom left with the SC rpm. To pulley back up to your original higher psi, then bleed off the added pressure above your current ~6psi, you'll end up with IMO's flat hp curve...but with your same current 370hp much lower in the rpm range. Your result will be strong hp access pre & post peak, without deviating from your safe 6psi setup. Just moving the powerband lower in the rpm like this will make a significant difference you'll lose the 2nd to 3rd bog completely.
Good stuff.
something to consider that I mentioned before is that your situation is much more favorable, having headroom left with the SC rpm. To pulley back up to your original higher psi, then bleed off the added pressure above your current ~6psi, you'll end up with IMO's flat hp curve...but with your same current 370hp much lower in the rpm range. Your result will be strong hp access pre & post peak, without deviating from your safe 6psi setup. Just moving the powerband lower in the rpm like this will make a significant difference you'll lose the 2nd to 3rd bog completely.
Good stuff.
10-18-2010, 06:07 PM
#63
Race Car
The variable that has to be added to this is gear ratios and driver skill. Imre and I have almost identical 1/4 mile times (Imre 12.87, me 13.06 both at 109 mph). With the 5 speed Imre has a 60' of 2 seconds, mine was 2.2. So after the first 60' our acceleration is identical.
On the dyno, Imre made 322 hp and 369 tq, peaking his hp at 5000 rpm and it staying level right to 6500. As you can see from my chart, I make 370 hp and 344 tq, but my hp builds all the way to redline. Below 5000 rpm Imre has the hp advantage.
With the autobox, I can stay at 5000 and above in 1st and 2nd gear at WOT, so my additional 48 hp will show an advantage. Once I shift to 3rd I drop to 4200 and Imre will be pulling on me because he will be making more hp. He also has an extra gear ratio which gives less rpm drop per shift which is another advantage. We haven't lined up but this is my prediction of how it will go down.
Moral of the story? A higher peak HP engine CAN outperform a lesser flat HP curve IF the driver has enough gear ratios and the ability to use them properly. The driver with the peaky engine will be shifting a lot more to keep the engine "in the zone" but it is possible. This is how high peaky hp sportbikes accelerate like a bat out of hell, very carefully selected gear ratios and lots of them!
On the dyno, Imre made 322 hp and 369 tq, peaking his hp at 5000 rpm and it staying level right to 6500. As you can see from my chart, I make 370 hp and 344 tq, but my hp builds all the way to redline. Below 5000 rpm Imre has the hp advantage.
With the autobox, I can stay at 5000 and above in 1st and 2nd gear at WOT, so my additional 48 hp will show an advantage. Once I shift to 3rd I drop to 4200 and Imre will be pulling on me because he will be making more hp. He also has an extra gear ratio which gives less rpm drop per shift which is another advantage. We haven't lined up but this is my prediction of how it will go down.
Moral of the story? A higher peak HP engine CAN outperform a lesser flat HP curve IF the driver has enough gear ratios and the ability to use them properly. The driver with the peaky engine will be shifting a lot more to keep the engine "in the zone" but it is possible. This is how high peaky hp sportbikes accelerate like a bat out of hell, very carefully selected gear ratios and lots of them!
Dan
'91 928GT S/C
475hp/460lb.ft
10-18-2010, 10:41 PM
#64
Captain Obvious
Super User
Super User
.......
With the autobox, I can stay at 5000 and above in 1st and 2nd gear at WOT, so my additional 48 hp will show an advantage. Once I shift to 3rd I drop to 4200 and Imre will be pulling on me because he will be making more hp. He also has an extra gear ratio which gives less rpm drop per shift which is another advantage. We haven't lined up but this is my prediction of how it will go down.............................
With the autobox, I can stay at 5000 and above in 1st and 2nd gear at WOT, so my additional 48 hp will show an advantage. Once I shift to 3rd I drop to 4200 and Imre will be pulling on me because he will be making more hp. He also has an extra gear ratio which gives less rpm drop per shift which is another advantage. We haven't lined up but this is my prediction of how it will go down.
............................Ohh but we did
.....at Hell,MI. I was behind you during the short run and this is exactly what happened when you shifter into 3rd. Even having 4 people in my car, I pulled almost right next to you as soon as you shifted into 3rd. Remember? 
10-19-2010, 10:10 AM
#65
Rennlist Member
Thread Starter
No sorry I don't know what you are talking about. I remember you accelerating but you were behind me so I cannot comment on whether you pulled on me or not. 
I do remember you pulling out to pass me, at about 50 mph, I mashed it and all you saw was my back bumper.
I do remember you pulling out to pass me, at about 50 mph, I mashed it and all you saw was my back bumper.
10-19-2010, 10:29 AM
#67
Rennlist Member
Thread Starter
Anonymous:
Here is an article I found where they maxed out the impeller on a Mustang and added a turbo waste gate to lower the boost for street use. Basically a more advanced setup to Carl's valve, has the ability to change boost levels on the fly. They show dyno graphs too which gives a picture of the hp curve.
http://www.musclemustangfastfords.co...all/index.html
Here is an article I found where they maxed out the impeller on a Mustang and added a turbo waste gate to lower the boost for street use. Basically a more advanced setup to Carl's valve, has the ability to change boost levels on the fly. They show dyno graphs too which gives a picture of the hp curve.
http://www.musclemustangfastfords.co...all/index.html
good note about impeller speed Imre, and making sure the unit used is appropriately pullied. Ted had indicated his original pulley was ~9psi, but without intercooler he was smart to decrease to 6psi.
Agree it seems like an adj pressure valve, but with Carl's testing for relief sizing, durability and possibly location, to be sure you don't have to trial and error on your own.
Agree it seems like an adj pressure valve, but with Carl's testing for relief sizing, durability and possibly location, to be sure you don't have to trial and error on your own.
10-19-2010, 03:09 PM
#68
Rennlist Member
That's exactly the concept, but with a much simpler equation to bleed off pressure (like Carl's valve), although a remotely adjustable setup would be nice 
Pretty elaborate setup on that Mustang with selectable boost options and 800+ whp; with a second aux tank for the high octane, all options can be ready at the flip of a switch!
Pretty elaborate setup on that Mustang with selectable boost options and 800+ whp; with a second aux tank for the high octane, all options can be ready at the flip of a switch!