Well, I am disappointed in my results. Here are my before and after times. The weather was very similar both nights, so I don't see that as being a big factor.

With my stock 3.23 gears and stock converter the car ran:
60' - 1.97
1/8 - 8.09
MPH - 90.25
1/4 - 12.46
MPH - 112.5

With 3.73 gears and the TCI 3800 the car ran:
60' - 1.66
1/8 - 7.70
MPH - 88.79
1/4 - 12.13
MPH - 113.15

Shouldn't I have picked up more than 3 tenths in the 1/4?? I am happy with the 60', but it seems like the converter isn't very efficient after that. By 3rd gear, it seems like the motor is screaming, but the pull is gone. The tranny is fresh and shifting very firm - I don't think that is the problem.

I put about 10 passes on the car over Friday night/Saturday - all of them in the 12.1X's with similar 60' and MPH. Anybody see anything I am missing? Mods are in the sig.

Maybe I'm wrong, but it seems that others have picked up the same 60', but then gotten .5 to .7 off of their 1/4 ET.

 

You lost almost 2mph in the 1/8th, something is definately wrong. How are your shift points, etc?

 

Yeah, something is strange with that. You picked up almost a MPH in the 1/4 but lost almost 1.5 in the 1/8? That's VERY odd. Did you see the same results in both lanes?

I'd check to see what the density altitude was on both nights too. Sometimes the weather can seem the same but the DA can be alot different. It's hard to judge barometric pressure just based on what it looks or feels like outside.

 

Shift points are good - 6400 RPM. The 1-2 was a little low at first (couple of hundred) but when we raised it up, no change in ET.

 

Yeah, I tried both lanes, even went to another track on Saturday. Same results 12.1X's and 1.6X 60' 112-113 MPH.

Could be that the weather was off a little. Like you said, hard to judge on feel. But if the weather was off, I would expect to see lower MPH if I was down on power.

I guess I am going more by the 1.66 60' and 113 MPH - you would think that would net an ET in the 11.8X's wouldn't you?

 

looks like his tranny is slipping...to loose mph in the 1/8 and gain 1mph at the top end is strange to say the least. you figure to loose 2mph at the 8th then he makes up 3mph at the top end...if he just stayed the same at the 8th he wouldve theoretically been at 115 which is a good enough mph for 11's.

lata
Bill

 

"I guess I am going more by the 1.66 60' and 113 MPH"

My car ran 11.82 at 113.12 MPH with a 1.61 60ft. This was with a TCI 3500. You shoud be 11.9s I would think.

 

My 4200 TCI dropped .3 even after slipping to the same 60 so it is definitely pretty efficient. I have dropped almost a full .5 and I didn't really hook all day. Only had the verter to the track once. Not bad for the first day. I'm still not done with experimenting on launches. I love it. The best mod for the car so far.

 

If you had a stock 3.23 rear in there before then went to a 3.73 Strange there's definitely some HP loss right there, but I agree that its odd that you lost mph in the 1/8 but gain it in the 1/4

 

Oh, I just realizd that he had 3.23 gears before and 3.73s with the TCI. Check this out...

With 3.23 gears crossing the 1/8 mile at 90 MPH you're at 6350 RPM in 2nd gear assuming 5% slippage and 26.2" tires. That's PERFECT for an 1/8 mile in a car that shifts at 6400. You're crossing the line just before your shift point.

But, with 3.73s you're looking at shifting into 3rd gearing and bogging across the 1/8 mile line. That's why his 1/8 MPH dropped while his 1/4 mile MPH came up.

 

That part about the 1/8 mile MPH makes sense! I knew you guys could figure it out for me.

So you think maybe that's just all it has in it? Or is there something slipping? The 1/4 ET is the only part that has me really puzzled.

Maybe my car is just a pig and needs to lose some weight? I was running full weight, with the 17" tires on the front and 26x10.5x16 ET Streets on the back. I don't remove my spare or anything, so I'm sure I'm pushing 3500 lbs at least! At least I'm a skinny little guy (150 lbs)!

I don't know, I guess I'm just a little disappointed cause I thought it would go 11's for sure.

Any other ideas?

 

I don't think you were getting the best launch that combo is capable of. I pulled 1.61 with 3.23 gears and at your weight and power with the TCI 3500. You no doubt have 1.5s in your combo if you can launch hard enough. You have better gearing and more stall than I had. You just need some serious traction to get into the 11s.

 

How high do you think I need to stall it up? I tried from idle to about 1500. It actually seemed to 60' best from idle. Do I need to try and get it up to 2000 or so and try there?

How else can I get the 60' down? It seems to be hooking - I don't feel any spin at all. When I did get a little spin, the 60' dropped to 1.78. Tire pressure didn't seem to make a difference - I went from 20# to 15#.

Do I maybe need an adjustable torque arm to get there?

Thanks for your help Colonel - I really appreciate it! If nothing else, you make me want to go back out and try it again. I was ready to hang it up for the winter.

 

If you're launching off idle with that converter then I can understand why your 60ft is what it is. You need the traction to launch stalled higher than that. You want to take those RPMs up fairly tight against the converter and then jam it HARD!!! when the last amber comes on. If she spins, that's not the converter's fault. You need more traction.

I would suggest LCA relocators and a new set of FULL slicks to start with. See if that gets you where you need to be. I also assume your front swaybar is removed or at least unbolted.

You're welcome!

 

BLK02WS6,
I think that the Colonel is right about your car. You should be able to 60' around 1.58-1.61 with your mods. Try stalling it up a little higher on the line and stepping on the throttle hard. In the same weather conditions as before, you should pick up around .5 seconds. You know, we can always upgrade to a 4400 stall and pick up a couple more tenths.
Kevin

 

"I went from 20# to 15#."

Try 11-12 psi. Make sure your gage is accurate. A low pressure gage is a must. Better yet, try a REAL set of slicks at 11-12 psi.

Stall it up to the point that the tires want to spin just a little and then back off 2-3 hundred RPM. If it spins on the launch then you need better traction. 1.5s are yours with that converter.

I think Kevin is being conservative when he says high 1.5s to low 1.6s. I think solid 1.5s are possible with your gearing IF you can DEAD hook it. Sometimes it's hard to sense just a little tire spin (but a little spin effects the 60ft more than you might think.) A video camera and a strip of shoe polish on the sidewall of the tire can help here.

 

Kevin and Colonel,
First - thanks to both of you for helping me.

I will try to stall it up much higher. I tried 1500 at the track, but that didn't seem to make a difference. I know just from sitting at a light and trying to see how high I could stall it (after yesterdays post, I wondered how high the brakes would hold) I can easily get it to 2000, maybe more.

I will take it to the track again and try stalling it like you said, and see how it does. Unfortunately, all I have access to are my ET Streets, but I think they are capable of holding much more than I was putting on them. Plenty of guys I know are cutting 1.5's on the same tires at the track I go to.

I will go lower on the air if I get tire spin. I like to start a little high, and lower as necessary to keep stability on the big end. It is easier for me to get used to the ride that way.

Let me play a little and see if I can get it down to the 1.5's - it is a good excuse for me to go back to the track (like I need one)

Is there any good way to make sure the tranny isn't slipping? Can EFI Live or Autotap monitor that in any way, or do they see the converter and tranny as one?

 

If the tranny is slipping then you should easily feel the "flare-up" on the shifts. The RPMs will quickly go up and then sloppily come back down during the shifts. The shifts won't feel quick and firm. It'll get worse pretty quick once this starts to happen.

 

That's what I thought - that is what my stock one did. No, this one is fresh and the shifts are very firm at part and wide-open throttle! It has all of the good stuff in it, so I am confident it is good to go.

I'll take your and Kevin's advice and head back to the track! I'll let you know with a new post how it goes! Thanks again!

 

get a yank ss3800 im at 390rwhp 385rwtq running mid to upper 11's 1.5...60'