Confirm understanding of lightweight mods

[SuperTom]

Originally Posted by mrg666

And it is not all about weight. There is vibration to consider as well. Reciprocating and rotating masses contribute to vibration differently. That is why race engines require a certain mass on the crank pulley. Because, while lighter crank pulleys improve throttle response, they cause vibrational power loss at high rpm. This has been discussed so many times but anyway. If I change my crank pulley, it will be Fluidamper which is not light but designed for damping of vibration at higher revs.

Looks like it mainly better for motors that stay in high RPM's all the time. The stock & Lightweight pulleys had better #'s in the torque dip range where the Fluidampr picked up top. It looks we are only talking about 2hp either way which could be influenced by other factors such as where the IAM is at 1 or lower during the run.


The one thing for sure is that weight is easy and accurate to measure and I know with my pulleys I saved 5lbs off the front of the car.

[mrg666]

Originally Posted by SuperTom

The one thing for sure is that weight is easy and accurate to measure and I know with my pulleys I saved 5lbs off the front of the car.

What is your light battery? I was planning to buy Odyssey PC680 to use four seasons in upstate New York where we have cold winters. Do you have any recommendations?

[SuperTom]

Originally Posted by mrg666

What is your light battery? I was planning to buy Odyssey PC680 to use four seasons in upstate New York where we have cold winters. Do you have any recommendations?

I have Shorai LFX36L3-BS12. Its a little bigger than the shorai others use but has more juice and still under 5lbs. https://www.amazon.com/Shorai-LFX36L...YC7KMPTVDWR0DQ


I keep the stock battery on a cheap harbor freight tender and switch it in around November so didn't really test in during the depths of winter. And I keep the Shorai on the same cheap harbor freight tender until spring.


Here is a cheap home depot battery cage I made as well
http://www.ft86club.com/forums/showthread.php?t=120937

[mrg666]

Originally Posted by SuperTom

I have Shorai LFX36L3-BS12. Its a little bigger than the shorai others use but has more juice and still under 5lbs. https://www.amazon.com/Shorai-LFX36L...YC7KMPTVDWR0DQ


I keep the stock battery on a cheap harbor freight tender and switch it in around November so didn't really test in during the depths of winter. And I keep the Shorai on the same cheap harbor freight tender until spring.


Here is a cheap home depot battery cage I made as well
http://www.ft86club.com/forums/showthread.php?t=120937

Thanks! I want to save weight but I don't want to swap batteries two times every year. Odyssey PC680 is 15 lbs but still ~20lbs lighter than the stock battery. I was wondering if anybody went through winter with that.

[86TOYO2k17]

Originally Posted by SuperTom

Im down to 2500lbs with still an ungutted interior. Major compromise I had to give up was AC delete for only 15lbs so I may consider putting that back in.


I did chunks at a time to feel the difference.
I did lighter wheels/tire along with lighter pulley
I did Lightweight Wilwood front brakes (-30lbs) and CF driveshaft
I did lightweight battery with rear seat delete
I removed front and rear bumper beam and same time
I did empty windshield reservoir & AC delete with spare tire/jack removal


The method was to keep the front & rear loss close each time to maintain the stock balance built into car.
Each time I noticed a drastic improvement in acceleration.


The OP's question will reducing reciprocating mass improve HP? No. But the car will get to the same HP #'s up high quicker is how I see it.

Where you able to get any before / after testing for any amount of weight reduction? 0-60 1/4m or any rolling pull would be must accurate probably?

I’ve only done a little testing just with different amounts of fuel. It seems like from my testing every 25lbs (4gallons) of gas less I have shaves .1sec off 0-60. Would be interested to see if your weight reduction shaved off .5+secs if you had any conclusive testing/data.

[86TOYO2k17]

Originally Posted by SuperTom

Looks like it mainly better for motors that stay in high RPM's all the time. The stock & Lightweight pulleys had better #'s in the torque dip range where the Fluidampr picked up top. It looks we are only talking about 2hp either way which could be influenced by other factors such as where the IAM is at 1 or lower during the run.


The one thing for sure is that weight is easy and accurate to measure and I know with my pulleys I saved 5lbs off the front of the car.

I have seen the stock vs Perrin lw, vs fluidampr dyno comparison. Lw crank seemed the worst. Stock was more balanced. And fluidampr had a much better top end for a slight decrease bottom end (although maybe something else was at play for it losing in the bottom like 1 IAM got pulled from previous runs)

However I have seen some s2000, mustang, and VW (not sure model) which all showed at least a solid 3+ hp/torque across the entire power band. With hundreds of people in those forums praising the pulley. It must not be as well known / tested in this community for some reason. Maybe ppl are to stuck on the LW pulley to try it.

[SuperTom]

Originally Posted by mrg666

Thanks! I want to save weight but I don't want to swap batteries two times every year. Odyssey PC680 is 15 lbs but still ~20lbs lighter than the stock battery. I was wondering if anybody went through winter with that.

With my cage its literally 30 mins to swap the battery. Read my thread the cage bolts down with 2 bolts to the stock piece under the battery.


The Shorai LFX36L3-BS12 has 36AH hence the # in the name and weights 4.5lbs
PC680s are old technology 16AH at 15lbs.
Your call man

[SuperTom]

No conclusive data but my BUTT. Of course there are calculators out there to get an estimate https://www.carspecs.us/calculator/0-60


Punching in my Flywheel hp at 190. A guess on my part going by others with Gruppe-S UEL and 93 octane OFT tune. could be a little more or less but its just a simulation


Punch in 2774 lbs = 0-60 6.244 seconds
Punch in 2500 lbs = 0-60 5.775 seconds


This is just for fun im not claiming these numbers at all


Also get to drive my Corvette on alternate days and guess what, many days I just like the 86 better it just feels quicker and livelier with the power and weight reduction mods

[86TOYO2k17]

I thought flywheel = advertised engine HP (200)
And wheel hp was measured at wheels after drivetrain loss.
Wouldn’t your Flywheel HP be more like 220?

Although putting wheel hp + adding my weight to vehicle did give me really accurate times. 165whp 3000lbs auto 7.9sec and 195whp 2950 6.9sec actually pretty close to my own tests.

Did you add in weight of driver and or gas? Curious if you ever weighed your car with full tank + you in it. Some times listed curb weight is iffy if it includes gas or not

But anyways it looks like according to that 50lbs weight reduction is .1sec off 0-60 still not bad. My goal is to get the car+full tank of gas to be lighter then stock with zero gas. So I won’t have any negative weight reduction from full tank in a sense.

[gtengr]

Originally Posted by 86TOYO2k17

Where you able to get any before / after testing for any amount of weight reduction? 0-60 1/4m or any rolling pull would be must accurate probably?

I’ve only done a little testing just with different amounts of fuel. It seems like from my testing every 25lbs (4gallons) of gas less I have shaves .1sec off 0-60. Would be interested to see if your weight reduction shaved off .5+secs if you had any conclusive testing/data.

FWIW, the faster you're going, the less of a factor weight loss is to acceleration.
A more accurate way to isolate improvements due to weight loss is to measure 0-35 or 0-40 (redline 1st gear). The influence of rolling resistance and aero drag quickly take over after 25-35 mph depending on a few variables.

[SuperTom]

Originally Posted by 86TOYO2k17

I thought flywheel = advertised engine HP (200)
And wheel hp was measured at wheels after drivetrain loss.
Wouldn’t your Flywheel HP be more like 220?

Although putting wheel hp + adding my weight to vehicle did give me really accurate times. 165whp 3000lbs auto 7.9sec and 195whp 2950 6.9sec actually pretty close to my own tests.

Did you add in weight of driver and or gas? Curious if you ever weighed your car with full tank + you in it. Some times listed curb weight is iffy if it includes gas or not.

Maybe 2700ish lbs with 220hp would be more realistic? Prob similar times though.

Yep you are right about the flywheel being the stock hp #. Personally I think the calculator is more accurate using WHP.


I know Stock C5 Corvettes are right around 305 dynod Whp and weight 3250-3300 lbs, with a 0-60 around 4.9. Using those #'s the calculator is dead on.
Using stock C5 hp of 350 flywheel lowers it to 4.4 seconds which seems a bit faster than it is.


Good points though didn't add in my own weight to the car which would make it 2500lb + 170 = 2670


Good question if manufactures add in the weight of a full tank of gas to there #'s I would like to know that. A gallon of gas is about 6lbs


Haven't weight my car but used an accurate shipping scale to weight each piece removed, or compared lighter pieces to heavier stock pieces to get my weight of 2500lbs (Using stock weight 2774). I will post my data sheet when I get home from work.

[86TOYO2k17]

Originally Posted by SuperTom

Yep you are right about the flywheel being the stock hp #. Personally I think the calculator is more accurate using WHP.


I know Stock C5 Corvettes are right around 305 dynod Whp and weight 3250-3300 lbs, with a 0-60 around 4.9. Using those #'s the calculator is dead on.
Using stock C5 hp of 350 flywheel lowers it to 4.4 seconds which seems a bit faster than it is.


Good points though didn't add in my own weight to the car which would make it 2500lb + 170 = 2670


Good question if manufactures add in the weight of a full tank of gas to there #'s I would like to know that. A gallon of gas is about 6lbs


Haven't weight my car but used an accurate shipping scale to weight each piece removed, or compared lighter pieces to heavier stock pieces to get my weight of 2500lbs (Using stock weight 2774). I will post my data sheet when I get home from work.

I did edit my last post in the time you where still replying it looks like lol...

Still fun to play around with weight/hp to see different guestimated results.

Do you happen to remember the weight of stock full header back? And the stock air intake noise generator and all?

[86TOYO2k17]

Originally Posted by gtengr

FWIW, the faster you're going, the less of a factor weight loss is to acceleration.
A more accurate way to isolate improvements due to weight loss is to measure 0-35 or 0-40 (redline 1st gear). The influence of rolling resistance and aero drag quickly take over after 25-35 mph depending on a few variables.

That is interesting. I could see that. So it would make less difference for street pulls and 40 rolls etc... I wonder then if there is any quantitative data / mathematical calculations for splitters/diffusers and aerodynamic reductions on say a 60-115mph pull?

[gtengr]

Originally Posted by SuperTom

Good question if manufactures add in the weight of a full tank of gas to there #'s I would like to know that. A gallon of gas is about 6lbs

US curb weight is 100% full tank per the NHTSA.