Desktop Dyno 2000 gave me 324 ft/lbs @ 4000rpm 296 HP @ 5500 at the flywheel... Do those sound about right for my setup? How accurate is this program. If this is correct, where should I shift?
they sounds really high considering my car is faster than yours, and my car dyno's around 230 hp.. 198 at wheels
Those figures don't sound too outrageous to me. I used to have almost the same combination and very close to the same output. Those P heads work very well. Simon, with his P heads and better rear gears, if your quicker I'd have to blame driver error on his part.
Which is why I also ask, "where should I shift" I think I might be holding out too long on the gears. The graph shows that torque levels at 4000-4500 then starts to drop. HP tops out at 5000, levels to 5500, then drops. I have always shifted around 5000-5500 (once at 6000, but I lost all kinds of time on that run). I never make it to 3rd gear on the 1/8th, and I wonder if I should shift at 4500 and not waste that 1/4-1/2 second trying to rev higher Simon, you are likely picking up a faster ET due in part to the higher stall converter, and smaller tires (diameter and rotational mass). I actually got slower when I went from 175/70r14 to 245/60r15, even though I added the spool and 3.80 gears. I think the tires are so much heavier that they are harder to start turning. I have since picked that time back up, and then some, with a larger cam (still too small) and better heads, intake, headers and exhaust.
I guess if nothing else, the program is good for estimating what a specific change to my setup will give me... --a 10psi centrifugal blower=75HP --a larger cam didn't affect HP and Torque much, but just moved it to a higher RPM range --UNLESS I swapped to a roller lifter, which added almost 50HP (paired with the larger cam) --only 20-25HP increases with each 1.0 increase in compression Little experiments like this are fun just to give me an idea what a change will make.
Do you get traction? What is your MPH? Do you have a converter? The numbers sound very reasonable. Your ET could suffer from some other problem like traction or some tuning factor. Dave
they sound a bit high. i usually figure 500 rpm over peak hp as a starting point for shifts. then experiment.
I get pretty good traction (3.80 gears with spool). But my tires are HUGE (255/60r15). Also, stock 1800-ish converter. It is fast, compared to most cars on the road, including sports cars, but not as fast as it could be. I have to sacrifice some of my FAST for streetability. I will someday swap the converter to something a bit higher, maybe 3000, but I really want to keep the car on the street, with a yearly (or three) trip to the track. My other two cars are a Hemi Dodge 1500 (360 HP) and a Supercharged Bonneville v6 (238 HP, or 268, something like that). I always thought these were both fast cars, until I made these mods on the Maverick. Of course, the Mav weighs HALF as much as both the others.... Last I drove the 1/8th, 9.4@76. Right at 14 seconds on the 1/4, if my calculations are correct. But that is holding to 5500 and crossing the 1/8 in 2nd gear. I am wondering if I should shift earlier and get to 3rd before I cross, and maybe add a little...
Yeah, your 3.80 gears aren't doing much with such tall tires. Your converter will make it a nice driver, but it hurts performance as well. Edit: Don't misunderstand, I don't think the tires are hurting you in any way except taming your gear.
When you ran it up to 6k rpm, what was the mph? Have you been able to get a higher mph, regardless of ET? Mph is the tell of HP, not ET. Edit: If your power truely peaks at 5500, I would expect to shift around 6000 for best results. You should shift over your peak HP and the next gear should land right at peak TQ rpm. So if your HP peaks at 5500, you should shift no sooner than 6, and maybe a little more if your next gear is starting at an rpm lower than your TQ peak rpm.
I agree 100%. I swapped gears (and added spool) at the same time I went to bigger tires, and next trip to the track, I saw no improvement. That is whay I tell Simon that his smaller tires might be the contributing factor (or one of them...his 306 should help a bit as well ) to his faster times. My tires are not only taller, but weigh twice as much as those thin ones I used to run...much harder to get rolling.
If we are going to go bench racing... You got: 1.5 points less compression 8 fewer cubes Less traction Heavier rolling mass rear (and front seems to me) No K&N (from what I can tell) And, you live where heat and humidity is a handicap compared to Iowa. Also, you may or may not have more restrictive muffs or pipes. They can make a big difference.
