importance of and improving power curve
Moderator: Team
importance of and improving power curve
Below is a couple pulling truck videos of the same pull.
One in cab and one from the stands.
Second place pull with 20 trucks in our class.
Shows how important a wide power curve can be.
https://www.youtube.com/watch?v=2fAWrog5Y_s
https://www.youtube.com/watch?v=MCbvK927ceA
I built a sled simulator so we could load the truck chassis the way a pulling sled does. Studied the hitch/chassis etc, and found some deflection we didn't like. So we made some changes to the chassis to help keep the truck hooked up better at the end of the pull, and have less hitch height loss under load. This past Sat. we tested the changes. ( the above videos )
It's the hardest it's worked the engine so far this year.
I hear some truck pulling guys say all that matters is power past peak, but,.... at this pull the power around peak TQ was worth some feet for our truck.
So how do you go about improving power at 9000 rpm plus, at peak HP rpm too (7500 ish) and at peak TQ rpm ? Or add power in part of the power curve without a loss at any other part. It kinda needs to be an EMC type of power curve but 3000 or more rpm higher.
I'm planning a bigger carb ( 1250 maybe ) and some better headers over the winter. May try a different cam but that's not likely to gain everywhere, but probably a trade for gain at some rpm for loss at a different rpm.
It was a second place pull so we still need to do better, and more rpm mid track would have helped, but not if it had less around peak TQ rpm.
You should here my son describe the sounds in the cab during that pull. LOL
Randy
One in cab and one from the stands.
Second place pull with 20 trucks in our class.
Shows how important a wide power curve can be.
https://www.youtube.com/watch?v=2fAWrog5Y_s
https://www.youtube.com/watch?v=MCbvK927ceA
I built a sled simulator so we could load the truck chassis the way a pulling sled does. Studied the hitch/chassis etc, and found some deflection we didn't like. So we made some changes to the chassis to help keep the truck hooked up better at the end of the pull, and have less hitch height loss under load. This past Sat. we tested the changes. ( the above videos )
It's the hardest it's worked the engine so far this year.
I hear some truck pulling guys say all that matters is power past peak, but,.... at this pull the power around peak TQ was worth some feet for our truck.
So how do you go about improving power at 9000 rpm plus, at peak HP rpm too (7500 ish) and at peak TQ rpm ? Or add power in part of the power curve without a loss at any other part. It kinda needs to be an EMC type of power curve but 3000 or more rpm higher.
I'm planning a bigger carb ( 1250 maybe ) and some better headers over the winter. May try a different cam but that's not likely to gain everywhere, but probably a trade for gain at some rpm for loss at a different rpm.
It was a second place pull so we still need to do better, and more rpm mid track would have helped, but not if it had less around peak TQ rpm.
You should here my son describe the sounds in the cab during that pull. LOL
Randy
Re: importance of and improving power curve
Needs more "bowl" MOO
Seriously, sounds really damn good. That little motor just doesn't wanna give it up!
Seriously, sounds really damn good. That little motor just doesn't wanna give it up!
Re: importance of and improving power curve
You always say the key to making more power is to reduce flow #'s... I am thinking a 1.94 valve on a 60* seat should be a solid 30 hp/tq gain.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Re: importance of and improving power curve
Actually as good as it runs I would be afraid to change anything but I think the dyno test showed the carb to be a restriction?
Have you been able to test others and or headers?
Have you been able to test others and or headers?
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Re: importance of and improving power curve
So,... I have the wrong cam,.. need more cubes,.. bigger bowl with less flowZZ???
Well, the cubes is probably out since Austin turned down the 474 cube big bore/short stroke sponsorship, but I've had lots of others willing to take me up on that sponsorship. LOL
Randy
Well, the cubes is probably out since Austin turned down the 474 cube big bore/short stroke sponsorship, but I've had lots of others willing to take me up on that sponsorship. LOL
Randy
Re: importance of and improving power curve
I guess I'll bite, not many takers here offering input. Just some thoughts without knowing every single detail of your 421.....Compression, more lift, headers for sure, Carburetor, more vacuum, try a bit more exhaust duration maybe....just throwing some stuff out there.randy331 wrote: ↑Tue Aug 28, 2018 1:02 pm So how do you go about improving power at 9000 rpm plus, at peak HP rpm too (7500 ish) and at peak TQ rpm ? Or add power in part of the power curve without a loss at any other part. It kinda needs to be an EMC type of power curve but 3000 or more rpm higher.
And remember "Area is your friend", "put some more bowl in it", "can't make any power with the valves closed" and "get the air column moving early"
-
- Guru
- Posts: 2282
- Joined: Wed Jul 27, 2011 5:22 am
- Location: brisbane AUSTRALIA
Re: importance of and improving power curve
Randy,
i see you welded the pinch and opened it to 2.6'' 240 cc approx 320 cfm approx with a 2.08'' valve?
do you think the head is maxed out for the 2.08'' valve ?
i ran a sim on yours with engine pro ( which i know you have as well) with your parameters you are 20 lbs/ft and 20 hp approx above and your cam parameters are close to what you have.
i am thinking 2.88 MCSA and around 260cc runner but i think you will need 2.10 valve and i read earlier you dont have the room.
what do you think helps carry the power way past peak and holds it there with ease by the sound of all the runs you have put up on line.
i have to be careful here as i dont want to dig a hole for myself and you bury me in dirt from my inexperience but just trying to learn a little.
i see you welded the pinch and opened it to 2.6'' 240 cc approx 320 cfm approx with a 2.08'' valve?
do you think the head is maxed out for the 2.08'' valve ?
i ran a sim on yours with engine pro ( which i know you have as well) with your parameters you are 20 lbs/ft and 20 hp approx above and your cam parameters are close to what you have.
i am thinking 2.88 MCSA and around 260cc runner but i think you will need 2.10 valve and i read earlier you dont have the room.
what do you think helps carry the power way past peak and holds it there with ease by the sound of all the runs you have put up on line.
i have to be careful here as i dont want to dig a hole for myself and you bury me in dirt from my inexperience but just trying to learn a little.
steve c
"Pretty don't make power"
"Pretty don't make power"
-
- Guru
- Posts: 5566
- Joined: Sun Feb 19, 2006 10:19 am
- Location: MA
Re: importance of and improving power curve
I’m not so sure you have a “power” problem. The engine does most of the pull at 9000, then only at the very end, it pulls down to peak torque before spinning out. It seems as the truck needs a little more speed and the engine has enough power to do that.randy331 wrote: ↑Tue Aug 28, 2018 1:02 pm Below is a couple pulling truck videos of the same pull.
One in cab and one from the stands.
Second place pull with 20 trucks in our class.
Shows how important a wide power curve can be.
https://www.youtube.com/watch?v=2fAWrog5Y_s
https://www.youtube.com/watch?v=MCbvK927ceA
I built a sled simulator so we could load the truck chassis the way a pulling sled does. Studied the hitch/chassis etc, and found some deflection we didn't like. So we made some changes to the chassis to help keep the truck hooked up better at the end of the pull, and have less hitch height loss under load. This past Sat. we tested the changes. ( the above videos )
It's the hardest it's worked the engine so far this year.
I hear some truck pulling guys say all that matters is power past peak, but,.... at this pull the power around peak TQ was worth some feet for our truck.
So how do you go about improving power at 9000 rpm plus, at peak HP rpm too (7500 ish) and at peak TQ rpm ? Or add power in part of the power curve without a loss at any other part. It kinda needs to be an EMC type of power curve but 3000 or more rpm higher.
I'm planning a bigger carb ( 1250 maybe ) and some better headers over the winter. May try a different cam but that's not likely to gain everywhere, but probably a trade for gain at some rpm for loss at a different rpm.
It was a second place pull so we still need to do better, and more rpm mid track would have helped, but not if it had less around peak TQ rpm.
You should here my son describe the sounds in the cab during that pull. LOL
Randy
Automotive Machining, cylinder head rebuilding, engine building. Can't seem to quit
Re: importance of and improving power curve
\
A touch less IN duration, more EX duration widen LSA out a bit... ??
Re: importance of and improving power curve
[/quote]
I’m not so sure you have a “power” problem. The engine does most of the pull at 9000, then only at the very end, it pulls down to peak torque before spinning out. It seems as the truck needs a little more speed and the engine has enough power to do that.
[/quote]
Fully agree with this statement
I’m not so sure you have a “power” problem. The engine does most of the pull at 9000, then only at the very end, it pulls down to peak torque before spinning out. It seems as the truck needs a little more speed and the engine has enough power to do that.
[/quote]
Fully agree with this statement
Re: importance of and improving power curve
If the engine is making peak HP at 7500, running it 1500 rpm past that is like pissing into the wind. The engine probably makes more Hp at 8000 than it does at 9000, so I would say to gear the truck to run about 8000-8200 early in the run,and that should improve sled speed in that part of the pull. This assumes you don't have a Mile Per Hour limit in your class.
By getting more sled speed early, that should get you further down the track before the sled load starts to drag you down. I know that in many pulling classes,mid range torque at the end of the pull is more important than top end horse power. I would concentrate on trying to make more torque with the engine... compression, cam , headers, cubes...
By getting more sled speed early, that should get you further down the track before the sled load starts to drag you down. I know that in many pulling classes,mid range torque at the end of the pull is more important than top end horse power. I would concentrate on trying to make more torque with the engine... compression, cam , headers, cubes...
Competition Fuel Systems Birch Run,MI. www.compfuelsystems.com/index.html 520-241-2787
Re: importance of and improving power curve
That is one of the finest sounds in the world.
Nice job. Your son has to be thrilled with the family results.
Nice job. Your son has to be thrilled with the family results.
He who is in me is greater than he who is in the world.
Re: importance of and improving power curve
We currently run a 27.06 final drive, to get the same wheel speed at 8000 rpm that it currently has at 9000 rpm it would need a 24.05 final. That would give it very similar axle tq to last years 355, and that set up gutted out at the end at every pull.NormS wrote: ↑Thu Aug 30, 2018 3:21 pm If the engine is making peak HP at 7500, running it 1500 rpm past that is like pissing into the wind. The engine probably makes more Hp at 8000 than it does at 9000, so I would say to gear the truck to run about 8000-8200 early in the run,and that should improve sled speed in that part of the pull.
You think the 421 would stay on line at the end with a 24.05 final ?
Tire speed/sled speed comes much easier with rpm than gear.
Randy