5.0 Dyno #'s with aluminum driveshaft?

[JeremyH]

Maybe I am missing it..I am definitely wrong every now and then, but wouldn't the light weight driveshaft show a gain at the wheels? It is freeing up HP at the wheels.

No, not peak gains anyway, see my post earlier. Due to the increase in acceleration from the less inertia lightweight ds, hp/tq will come on sooner and should plot above a pull with a stock ds down low, but at max rpm/speed once a 18lb ds and a 30lb ds are moving at that speed the peak hp output on the dyno will be the same. The lighter ds car will just get there faster. It's physics, it takes more power/load to get a car up to 60mph that to mantain that speed once your there regardless of weight. The lighter car will just to get to that speed faster.

 

[Drex]

Thx for explaining, that makes sense

 

[zxmarekxz]

No, not peak gains anyway, see my post earlier. Due to the increase in acceleration from the less inertia lightweight ds, hp/tq will come on sooner and should plot above a pull with a stock ds down low, but at max rpm/speed once a 18lb ds and a 30lb ds are moving at that speed the peak hp output on the dyno will be the same. The lighter ds car will just get there faster. It's physics, it takes more power/load to get a car up to 60mph that to mantain that speed once your there regardless of weight. The lighter car will just to get to that speed faster.

thanks for the detail. I always thought that heavier drivetrain/wheels would show on a dyno. Guess I was wrong, not the first time. I guess it's like having a lighter car with the same hp being faster. Just so I'm clear, you're saying that I could put 40lb rims on the car and it still wouldnt show lower peak whp numbers?

 

[s8v4o]

Technically, you don't gain anything with a driveshaft. You free up power.

I love the Powerhouse on my '05! One of my favorite mods. However, it was also one I waited on, until I had most other bolt ons.

Come to think of it, I already had my Kenne Bell before I swapped it out.

Found a great deal (somewhat locally) on it, and I picked up a barely used one.

I never had any vibration issues with mine.

Make sure you have an adjustable UCA so you can set your pinion angle when you swap out the shaft.

I prefer -3* with a mostly street application.

Depending on your application you may want to set it a little different.

Technically you're right, however if it frees up power then your RWHP should go up, just not BHP. Is the motor making more power, no. As somebody already said. If it makes you go down the track faster via increase acceleration due to less rotational mass, then it should show on the dyno. It just won't show on an engine dyno.

 

[KungFuHamster]

Just so I'm clear, you're saying that I could put 40lb rims on the car and it still wouldnt show lower peak whp numbers?

correct.

look at it like this.

take your car and weigh it, say it weighs 3800 lb and then go make passes at the drag strip.

then remove 200 lbs from the car, add 0 hp and go back to the track. your dyno numbers will be exactly the same yet the car will be faster. ya dig?

 

[zxmarekxz]

correct.

look at it like this.

take your car and weigh it, say it weighs 3800 lb and then go make passes at the drag strip.

then remove 200 lbs from the car, add 0 hp and go back to the track. your dyno numbers will be exactly the same yet the car will be faster. ya dig?

yeah that part makes sense, but thats static and not rotational mass. If the rest is also true why is hp at the tire not the same as at the flywheel? I'm not trying to start anything, but I need to be clear on the whole picture, not just parts. just how my mind works.

 

[KungFuHamster]

yeah that part makes sense, but thats static and not rotational mass. If the rest is also true why is hp at the tire not the same as at the flywheel? I'm not trying to start anything, but I need to be clear on the whole picture, not just parts. just how my mind works.

ok look at it like this.

what is it exactly that "makes" power in a combustion engine? cylinder pressure at a peak rpm to put it simply.

you have a crankshaft that spins and pumps the rods and pistons which turn the clutch, driveshaft and so on.

reducing the weight of some of these items that are behind the motor allows the crankshaft to turn easier, thus the ability for the motor to rev up and reach its peak hp quicker/easier. but the motor itself is still producing the exact same power, it just gets to it hp peak quicker, like adding a lower rear gear.
this is why the car will seem faster without actually making or seeing any additional hp on a dyno

 

[Grabber]

Reducing rim size is rotational mass, as well as rim width.

A Driveshaft is less rotational mass followed by less weight compared to the stock 2 piece driveshaft.

Do people see results at the track by running 15-16 inch rims compared to 17,18, or even 20 inch rims? Yes. Do they gain RWHP on a Dyno? No.

A drive-shaft provides gains you will not see on a Dyno, however, it will prove itself on the street or at the track when your car accelerates faster.

 

[Drex]

Again, I'll trust those here that are smarter than me on this subject, but I will test the theory anyway. Soon as I install my SC, I'll do a baseline pull, then install a new drive shaft and do another pull.

 

[zxmarekxz]

ok look at it like this.

what is it exactly that "makes" power in a combustion engine? cylinder pressure at a peak rpm to put it simply.

you have a crankshaft that spins and pumps the rods and pistons which turn the clutch, driveshaft and so on.

reducing the weight of some of these items that are behind the motor allows the crankshaft to turn easier, thus the ability for the motor to rev up and reach its peak hp quicker/easier. but the motor itself is still producing the exact same power, it just gets to it hp peak quicker, like adding a lower rear gear.
this is why the car will seem faster without actually making or seeing any additional hp on a dyno

I was talking about whp only. why the 15% drive train loss then if things behind the motor dont show up on a dynojet?

Reducing rim size is rotational mass, as well as rim width.

A Driveshaft is less rotational mass followed by less weight compared to the stock 2 piece driveshaft.

Do people see results at the track by running 15-16 inch rims compared to 17,18, or even 20 inch rims? Yes. Do they gain RWHP on a Dyno? No.

A drive-shaft provides gains you will not see on a Dyno, however, it will prove itself on the street or at the track when your car accelerates faster.

Sure, but the tire could be much heavier on a 15-16 inch combo and being further out on the outside actually ending up worse that a heavier rim and lighter tire package. I've read in the past about people seeing whp gains switching to a lighter wheel package, but i'm talking about 10lb off a tire/wheel combo. I'm not saying that it's always the case or that they couldn't have been smoking crack.

as far as drive shafts go, I can't comment.

 

[robvas]

Resurrecting this one from the dead, but a lots of false info in the thread

 

[Dino Dino Bambino]

This video answers the original question.