Thought this could be a possiblity why some owners trucks aren't going faster than 100mph. I thought that the torque converter may not be locking up like its suppose to. Any comments or feedback guys/gals

 

See my thread on my transmission problems :-)

its not yet resolved but this could be part of my problem. I'll keep ya posted.

 

Heres a thought. Think about the aerodynamics of the front of the Lightning (its approximately that of a 4X8 sheet of plywood), now imagine pushing that piece of plywood down the highway at 100 mph. Do you think there might be alot of wind resistance? Well the wind resitance on the frontal area of a truckforces is tremendous at high speeds. The wind resistance is a function of the square of the velocity. This however would not explain why some trucks are not going faster than 100 mph, however it could explain why some people feel that their trucks do not feel like there are accelerating strong past 100 mph.

[This message has been edited by Peter B (edited 02-11-2000).]

 

THANKS PETER:

I'm glad you said it

The converter does not lock up under full throttle. If your L is running ok up till the 100 mph mark, it's not the converter. If the motor is not free reving, at a 100 mph it's not the tranny.

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JIGAWATT SVT#2698
N.L.O.C. Member
4:10's
Bassani kit
TransGo shift kit
AIM 2 inch drop shackle

 

Here is another thought for you while you are talking about aerodynamics. The only thing the Lightning and a piece of plywood have in common is that you can haul the later in the former's pickup box. As for the frontal area the Lightning is a stylized metal sculpture with a very good coefficient of drag. It does very well at over 90 + MPH. If for some reason some owners are having problems at that speed it is because their trucks are not running very well. If anyone has any doubts just view Nathan's Fly-by. Now there is one hump'n Lightning.

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BABolt
SVT#290

 

The convertor doesn't lock up at full throttle??!! Who the heck told ya that?!! It sure does. And it makes a huge difference on the 99.

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SAL
13.35@103mph
All stock with PSP 99 Lightning Chip and Filter Kit

Power Surge Performance--- Your SOURCE for SVT Lightning EFI Tuning and Performance!! http://members.aol.com/NLOCsvt/svt.html

 

I stand my ground with Sal on this one. The TC has to lock up at full throttle. Sal, is there a way someone can test and see if their TC is locking up when they try to accelerate over 100 mph? I know on my Syclone when the TC locks up in overdrive you can feel it, but not sure on a Lightning.

I'm assuming this is something the computer controls so maybe Sal can shed some light on this.

[This message has been edited by Pacecar18 (edited 02-11-2000).]

 

The torque converter lockup is in essence 4'th gear or overdrive if you prefer. Yes, it is designed to lockup. I brought up the torque converter thing on the guy who thought he was having transmission problems when he couldn't get over 100-120. That is nearing the shift point of the lockup and if it doesn't then he'll hit the rev limiter. It would show full boost but the fuel would cut off. The rev limiter on my Splash was so subtle that I didn't notice it was that until I tried winding it out more in 4'th(stick) and it hit it with much more kinetic energy.

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Red 99.5 Lightning,
#0975,
Born 5/6/99...Adopted 5/27/99
Chipped w/SuperChip Flipchip chip,
PSP Filter(track untested),
Water Wetter,
Mobil 1,
Foglamp Covers,
13.573@101.08




[This message has been edited by 4D THNDR (edited 02-11-2000).]

 

I just Think its cool you guys can complain about your truck Bogging down at 100 mph. Thats like top end for me.

MUST BE NICE

Just dont hit an armadillo @ that speed. OUCH!!!!!

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98 F150 2WD,Bright Red, Regular Cab, 4.2, 3.55, 5 Speed, Superchip, 2 Superchip Decals (I Think They Add 5 HP Each), 3 Inch Bullseye Lift Spindles, Manik Grill Guard,Nerf Bars, Vent Visors,Air Box Mod, Fog Lights Mounted In Front Air Dam ,2 Kc DayLighters, Back Up Lights, Alpine CD Player, 2 Kenwood Amps, 10 Inch MTX Blue Thunder SubWoofer, Tinted Windows. 3 Inch Body Lift Kit Is Here And I've Ordered the 16.5 x 9.75 American Racing Baja Wheels Wrapped With 35x12.5x16.5 BFG All Terrains So When They Get Here I'll Be Having Fun That Weekend

'00 Toyota Celica GT( Wife's Car )

Pics @ http://www.angelfire.com/la2/ccla/

 

I read someplace that the Lighting's CD (coefficient of drag) is a .44. Does anybody know anything about that? .44 seems kind of high for a vehicle designed for aerodynamics, including a truck.

My understanding is that a CD of .30 or lower is super for a factory production vehicle.

 

One thing to remember about drag: vortex drag is often equal to or greater than surface drag.

Surface drag is what most people think about. That is the drag created by airflow over the skin of a vehicle (such as the sides of our trucks and the front).

Vortex drag is the drag created when air flows over a vehicle and then does not meet smoothly at the rear. The air creates eddies which are regions of low pressure that hold the vehicle back. A perfect example of this is your mirrors. They have low surface drag because of the rounded front, but the flat back creates a ton of vortex drag (and noise. try folding your mirrors back when on the highway sometime).
Our trucks create vortex drag behind the cab at the rear window and behind the tailgate for those of your with bed caps. On our trucks this is a significant cause of drag. I have little doubt that these trucks could hit 165+ with aerodynamic fairings or even a properly designed scoop duct on the roof. However, the sharp edge of the tailgate is also why these trucks are so stable at high speeds. A uniform edge creates a uniform eddy which can act as a stabilizing damper.

 

4DTHNDR, I'm sorry, but your statement is completely wrong. Lock up is not O/D. Overdrive is a seperate gear, and has nothing to do with the convertor. The convertor locks up in all gears except first. It has it's own maps in the software, of when it comes on related to vehicle mph and throttle posistion. It can be infinately adjusted. When you turn the O/D button off, you are going into 3rd gear, which is a hydraulic change, not a convertor one. Think about this- you know what it feels like to be doing 60 and turn the O/D off, right? Now if your doing 60 and you tap the brake, does it kick into 3rd? No. But when you tap the brake, the convertor unlocks.

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SAL
13.35@103mph
All stock with PSP 99 Lightning Chip and Filter Kit

Power Surge Performance--- Your SOURCE for SVT Lightning EFI Tuning and Performance!! http://members.aol.com/NLOCsvt/svt.html

 

Nathan, are you saying that the CD rating is a combination of both surface drag and vortex drag?

 

I took a hi-perf. class where we had adyno to measure rear wheel hp at any given speed . We tried a 62 vette [ I know but its what we had] and at 55 we took a hp reading by using a vac guage and duplicated the read to get the hp and at 70 ,80 and 100 and it almost cubes itself. I ran the silverstate in a 93 and I ran a little over 2/3 throttle at 130 but to getto 135 I was wide open , thats with 356 at the rear wheels , and lockup is working at wide open throttle for sure.

 

So, is the top speed on an L. drag limited or governor limited?