how much et time does each 100lbs of car weight cost

I went to the GS Nationals in 1992. My fully loaded '68 GS350, except for power windows, did 15.99 @ 90 MPH. I took out the back seat and EVERYTHING that was in the trunk. It was packed with vacation stuff. It ran 15.99 again??? Maybe all the stuff I took out didn't weigh that much? I dunno. But... I accidentally locked the keys in the trunk. My 2 year old was able to barely squeeze through the metal framing behind the seat and get my keys. Glad I took the back seat out if only for an hour or so.

 

if you want 13.9
you will need at least 450 hp at the crank in a big car

i started at 16.2 first time out(big block)@4600 lbs
fine tuning and a better converter got me mid 14's

i think i was putting 290 hp to the rear at that time

you want 13's get a fresh 455 with 450 hp good converter and have at it

J

 

The Buick rally wheels ARE sharp looking for an OEM wheel, very sporty looking in my opinion, but yes they are heavyp

 

:bglasses:

 

And then you can also get into topics such as reciprocating weight (pistons, valves, pushrods) and how much efficiency can be gained with light but still strong components. Reciprocating weight is any component that needs to change direction quicker and quicker as RPM increases which is why it is such a big deal. So like with a heavy stock piston the weight is actually hurting the strength of the engine and adding extra stress to the rods, crank, and bearings because of the forces of the change of direction... Replace a 700 gram stock piston with a 555 gram forged piston and you will gain both more engine reliability and higher RPM capability if the engine is re-balanced. And you will increase your engine performance with the lighter pistons as well.

Where as a crankshaft, or a wheel, is just rotating weight turning over and over and making it lighter does reduce the parasitic loss (or waste) off inefficiency of engine power. However the thing with rotating weight is that the largest gain in weight reduction here really helps the acceleration or deceleration more than anything. This is another example where the super stock racing guys go to extreme lengths to reduce the rotating weight in the transmissions because they have a limited amount of HP and TQ that they can make so they need to get every bit of the power possible to the tires. Where as for the rest of us we can just bolt on some parts to make more power instead of spending a huge sum of money on lightening the transmission components.

 

Added weight can't help accelegate anything, if it's hei vier and to want to speed it up it will take more power. No to maintain a set speed the heifer weight will help that. Inversely, to slow it back down the heifer weight will now take more effert to slow it down. A car with big heavy wheels will also take a longer time and more brake effert to bring to a stop.

We have all heard something in motion wants to stay in motion. Ever take a bucket of sand at the beach and windmill it, hard to get going. Once spinning it's easy to keep the speed, but as you try to stop you have to put effert into it. Now if we want to get real technical the farther from the center axis the weight is also effects this. Example. Rotors with the main part of the weight in the hub, take less power than a drum with the main weight towards the outside.

The transmission parts really pay big dividend cause those parts don't just spin. Sometime they have to instantly stop then spin a differant direction. So it's not just start to spin, but a stop and start again. While other parts might be spinning several times over input speeds.

 

6.183 pounds = 1 gallon of gas.

have 1/8 tank of gas.

make a et pass.

put in 16 gallon of gas 100 lb

note how much car slows down.

your done.


Dan

 

I like Dans idea.

Some vehicles would do the quarter mile quicker with 100 pounds added while others would run almost the same as demonstrated by the Buick Skylark with the rear seat etc removed.

Take a turbo diesel one ton truck and run it with and without 100 pounds and I bet it would not make a difference as it makes so much torque. Plus there is the factor that someone mentioned about the ratio of the increase of the weight increase vs the weight of the vehicle.

Take a 78 Buick Skyhawk and add 100 pounds and I bet it would slow down the car both because the ratio of the total weight vs weight added is different and because the engine has less torque.

I still think your big land barge would be great with twin turbos...

 

sign me up.

 

I 100% agree! My 73 Estate wagon weighs about 5300lbs and has run an 11.72 at 117 so far. (pretty sure it pooped the head gaskets on the last run)

I agree with everyone else, all the figuring in the world won't replace one day at the track.

$35 to go to the track once a month for 3 years will probably still be cheaper than getting out of 1 ticket! And at the track you'll have hard numbers to work with.


Find some other people with big cars, go to the track once a month (OK, twice in the summer), cook hot dogs on the grill, make passes and have fun!

A friend and I used to take our wagons (mostly stock) to the local track and pair up just for fun, and it was fun.


The more I read these threads, the more I want to get my butt back out there and do it again! :grin:

 

now if you were going land speed racing you would be ADDING weight for speed which then you would need h/p to overcome the weight and aerodynamics. :laugh:

 

5300lbs 11.72 seconds? what did you say your engine and drivetrain combo was?

 

I'm sure 13.9 is doable in the heavier car. You will need plenty of power from engine. But trans, rear end and chassis needs to be right to get it there also. I would go with a 700 or 200 overdrive trans and run some deeper gears. Torque multiplication can help a lot . Would like to see a 13 second 350 big car. If you convert to E85 fuel you can run higher compression for a bit fatter torque curve. If a 3800 lbs car can run low 13s assume that engine can possibly loose 6 tenths for 600 lbs added . I think you can Build for lots of torque. the big cars run a 28-29 inch tire . So more gear can change up acceleration out of the hole quite a bit. 3.73/3.90 or 4.10 for more race then hiway. Goals are not that far from reach in my opinion considering how many low 13 seconds cars are here.

 

Get to the track and practice also. You will need good reaction times, need to know how to launch/ traction and what rpm shifts should occur for best et. That could make the difference between 13.9 and 14.4.

 

Run a 410 gear with a 4 speed auto 200-4r with a 2800 stall convertor comes to mind here, Get the motor up to 10 or 10.5 on the compression throw in a 212 cam, use a Q-jet or a 650 double pumper Holley with the Dual plane TA intake.

If you want the Single plane intake you want the 10.5+ compression with a bigger cam to take advantage of the upper rpm that is going to come and you will need good rods and pistons to go with this set up to stay together, and a 3200 stall convertor. Now get to work.

That big car will move down the road then.

 

Just to clarify, Reaction Time has no bearing on ET, clock doesn't start till you break the beam

 

Twin turbo 455, EFI, TH400 with a too-tight converter (I think), GearVendors OD on the rear of it. A ford rear with a 3.50 posi. I added intercoolers last time, but they didn't help that much. I need to sort it out more, get it to 60ft better. Around 10 lbs of boost.

I think a sorted out blow through system will do just as well.

 

how much hp and torque at what rpm

 

I really don't know! I've plugged the numbers into online horsepower calculators and come up with 650 based on the ET, and 665 based on the MPH. That's supposed to be crank HP. If I could get it to scoot off the line those numbers would be better without changing anything else.


http://www.so-carspeedshops.com/RACING/tabid/304/Default.aspx (It's at the bottom of the page.)


I should also mention that the engine is painfully stock. Iron heads, unported, with stage 1 valves. Forged factory style pistons, stock rods, stock crank, small-ish cam, stock early style rockers. I did use coatings on the inside to help it live. Piston skirts and pins, exhaust valve stems, and bearings all have a low friction coating. The piston tops and exhaust valve faces had a heat barrier applied.

Most of the money has been spent on what bolts to the outside of it.

 

Go to the trackp
Its FUN!