bodak1

Forgive me if I am not using this correctlly-not familiar with all of this web terminology. I have a 90 Lingenfelter ZR 1. I am wondering if anyone has tested to determine whether their launch (60ft) and et improves with the additional weight in the rear from a full tank of gas vs slightly less than a 1/2 tank. My best time on a cold day in May was a 60 ft time of 1.809 with an et of 11.605 and 127 mph on bf goodrich drag radials (315's)

lead foot 85 vet

I would say a full tank for the added tracktion

JOHN89

If your running drag radials then 1/2 tank or slightly less. You will have to test to see at what point you get the "C4 bog" from too little fuel.
Mine seems to be just above 1/4 tank so I race with a 1/2 tank of fuel.
John

GIJoe

Less weight of the gas will help out after you are rolling though...
I go as empty as possible.

let some air out of your rear tires if you have traction problems.

neat

I usually have to have mine pretty close to full. Less than 1/2 a tank and I'll get a fuel starvation based bog if the car leaves hard.

I use nitrous, so running out of fuel on the launch is pretty dangerous. I'm not willing to risk it so I run with a full tank most of the time.

Your 1.8 isn't a terrible 60 foot time, but there is room for improvement. Here's a couple things I'd like to know before offering anymore advice:

Are you spinning or bogging off the line?
What clutch are you using?
What kind of HP/TQ does the engine make at 3500, what are the peak HP and TQ numbers, and what RPM do they occur?

PDQUIK95

Concur with above,
I have found that 1/4 tank will cause a hesitation at launch due to fuel being forced away from the pump causing it to pick up air momentarily causing a drop in fuel pressure to the rail. The car will feel a momentary loss of power then pick up again once fuel hits the pump.1/2 tank seems to be about the lowest recommended for weight reduction and to ensure fuel pressure when drag racing.
Rick

mackeyred96

I solved the problem with a 5 gal fuel cell.

JOHN89

Yup A 5 gallon fuel cell will do the trick!

0ski_dwn_it

Gotta run mine filled to the brim otherwise it sucks air and bogs. Doesn't help carring 150+ lbs exra weight.

Will soon be coming up with a solution for us all Just need a little time.

bodak1

The diff. is a 4.09. Using standard clutch. At 3500 rpm, hp is about 270 at the crank and torque is about 380. Maximum output is 581 hp at 6700 rpm, and max torque is 480 ft lbs at 5500 rpm. I am not bogging, but traction is a problem. I don't think i have been doing as good a job heating the drag radials as i should. Will work on that on Sept 12 when i go out again.

bobmic93

1/2 tank and less psi if still having traction problems.

wayne lowry

I run a full tank of gas or close to it.

A95Y

Nice piece

neat

Cool deal man, nice car.

You might try tightening the monoleaf nuts about another 3/4 of an inch. Just pull the cotter pins and use a ratchet/socket to run the nuts up about another 1/2-3/4 of an inch. That should give you some more positive rear camber which should help you flat the tire on the track when the car squats down.

If all you do is drag race, there are some rear alignment settings that will help you hook the launch, but you will sacrifice some handling. I doubt you'd notice it on the street, but your times at an auto cross or road race would be slower. Shoot me a PM if you want those specs.

You can also try building/buying and adjustable heim link for the passenger side of the rear sway bar. Lengthening the link on that side will help by preloading the passenger side rear tire.

Look under your car and see if the top of the knuckles have been hitting the rubber snubbers. If it's obvious that you aren't hitting the snubbers, don't worry about anything, but if there are some marks on the knuckles or the snubbers where it looks like it's been making contact, you might consider some snubber spacers. I built my own, but there are some vendors who sell them. They are just simple 1 inch thick blocks that bolt between the car and the snubber, effectively moving the snubber 1 inch down. Moving the snubbers down 1 inch will keep the rear end from going past parallel when you launch the car. Basically, in stock configuration, if you are on the snubbers when you launch the centerline of the rear end is actually lower than the centerline of the wheels. The half shafts will actually have to travel up to get to the wheels. By dropping the snubbers 1 inch, when you ride the snubbers the centerline of the rear end and the wheels will be parallel, making the half shafts run in a straight line to the wheel.

Here's a pretty cool write up/website about launching cars. The launch technique described here is probably the best way to get your stock clutch off the line effectively without ruining anything:

http://www.rangeracceleration.com/Launch_Tips.html

Last, be careful with that kind of power and the stock clutch. I would think you are very close to overpowering the stock unit, and I'd hate to see you have to get the car towed home.

cv67

What kind of psi are you running in the front and rear? Front sway bar on?

Too little pressure in the rear can cause the tires to "cup" lessening the contact patch on launch and actually hurt your mph.

REDC4CORVETTE

I have to run my gas gauge 2 noches above the 1/2 tank mark or it will bogg.I have measured the fuel at that level for my gauge and it is about 10 gallons.If the tires hook and bring the front off the ground then the car starves and slams down.The DR tire needs to be burned real hard for the first run and they should just need a minium burn after that.To much burn and they get greassy.
I run 16 lbs in my DR and 8lbs when I run my slicks.
I have tried the alignment spects for drag racing and I have tried the stock settings,When I have my alignment done I make sure it is set to factory,if they give you an excuse why they can't set to factory,then fix it .Do it right or on one of your runs it will make a left turn for no reason and scare the hell out of you.
Don't worry about the 60' just carry it about 200 rpm's more in each gear to make up for the loss.I run Nitto DR 315's on the car for the street shoot out class and they hook fine if you set them up right.I run 10.46 with the DR's so you should not have any problem.I would be aware of the DR's most are not Z rated so becareful with your speed,the tires will come apart,ask me how I know I lost one at 137 mph.

GS4-LT1

If your running mid 11's and only getting a 1.8x 60' time you need more traction. I was running 13.1's and getting 1.88 60' times with zero wheel spin. If I were you I would fill the tank. the extra weight will be less of a factor than spinning your tires off the line. Also, as another member commented, do not "deflate" your tires below recomended psi. Radials will "cup" and hurt you even more. Good luck and let us know how you do in September!!!

bodak1

Thanks for all of your suggestions. I will try to put them to use. fyi, I had the rear DR's inflated to 20 lbs and the front at 40 lbs. I noted that 18 seems to be the low end per the mfgr, but i also saw something that suggested 12 lbs, but to reinflate before driving on the street (which i don't do).