Howdy guys. . . Just looking for some opinions on a strange phenomenon that happened with my car after installing a 3200 stall converter.

First a little background info:

My car is a 1999 Z28 A4 with 34,000 miles on the clock. I bought it last summer with 32,000 on it bone stock down to the paper filter. First thing I did was get all of the fluids changed out including servicing the trans with all new fluid and filter.
*This included replacing the FUEL filter.

Of course it wasn't long until the mod bug bit me and did the usual to it, Lid/K&N, Cutout, TransGo shift kit, Subframe connectors, Hurst line lock, and even found a good deal on a complete rear end from a 2002 M6 Trans AM and replaced my 3.23 gears with the 3.42 setup w/TA girdle. After putting on drag radials, these mods took me from a 14.03 @ 97.5 mph stock, down to a 13.83 @ 101.45 with a 2.075 short time here in Las Vegas where the elevation is well over 2000 feet.

Of course this only gave me the need for more speed, and after joining the local LV-F-Body Club and learning what others had been doing to their cars, short of throwing out the seats and going for the weight reduction, I decided the next mod I would get done would be a Vig 3200 stall converter and have the 4L60E rebuilt with all the blue plate clutches and Kevlar band, etc. One of the members of our club has a transmission shop and hooked me up with a package deal on all of the above. One of our members has an 02 T/A and with the mods I have plus LT headers and M/T ET streets, is running 12.7xx times out here at our track.

I decided to get the trans work done first and follow that with the new Jet Hot LT headers & Y pipe which BTW, are being installed as I write this.

Now, here is my problem. I had the trans work done and with the new Vigilante 3200 vert installed, along with putting on some M/T ET streets (26/11.50/16) I headed to the track. I dropped the tires down to 17 lbs to begin with and ran a new best of 13.69 @ 98.65 mph w/1.88 60' on the first pass. I thought there must be something wrong with the clocks for my trap speed to be that low, but repeated the same numbers on the next pass within thousandths.

I decided that a car like mine that only dynoed 306.28 RWHP & 317.27 RWTQ might not have the power to turn those ET streets on top end with the pressure that low, so put them back up to 22 lbs and tried again. This time I ran a 13.645 @ 99.46 mph w/1.871 60' and for the rest of the weekend this was repeated over and over again within a couple of hundredths. I was pretty happy with the new short times, but needless to say, disappointed in the overall gain in e.t. and just plain FLABBERGASTED with the pitiful trap speeds.

I have talked this over with a few people here locally, and opinions vary as to the cause of the lack of performance gain. Some think it's the tires and not having enough HP to pull them on top end. Most think it's the new converter not locking up.This has been run by the local LS1 Edit experts, and they didn't have any answers other than the 1999 cars were always a little down on HP & TQ compared to newer LS1 cars. (After the new LT headers are on, I might pick up a few more ponies) However, the old rules of thumb on how the short times equating to double on the top end don't seem to hold water in my case.

Here is one time slip for you to analyze with all the numbers:
60'= 1.871
330'= 5.598
1/8= 8.689 @ 80.34 mph
1000'= 11.362
1/4= 13.645 @ 99.46 mph

I have had NO tuning done on this car to date. The PCM is in stock configuration, so do you guys know of anything that might be done with PCM programming or anything else, to help this situation? Sorry for the length of this post, but I wanted to give some details in order for an informed opinion to be drawn.

Thanks in advance for any ideas, especially from anyone who has FIRST HAND experience with this same problem. Of course all opinions are welcome.

 

Higher stall converters are "less efficient", they still slip a little more than a lower stall converter will on the "top end" and you may see a reduction of mph, but et will drop due to torque multiplication off the line. That is the technical side...I think TCI talks about that on their website somewhere....good luck.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by trackbird:
<strong> Higher stall converters are "less efficient", they still slip a little more than a lower stall converter will on the "top end" and you may see a reduction of mph, but et will drop due to torque multiplication off the line. That is the technical side...I think TCI talks about that on their website somewhere....good luck. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">----------------
Thanks for the reply Trackbird, and that issue you mentioned about the "efficiency" of a high stall converter is one that I have read about as well. I was wondering if there might be any solution to this loss on the top end due to the converter not locking up? I was hoping there might be some way of making it lock up after a certain speed/rpm in a certain gear. This might have to be done with a switch, or possibly there's a way to program this into the PCM? I think the LS1 edit will deal with certain trans issues, but not sure if it can control the lock up charactaristics.

Anyone else have any experience with getting one of these converters to lock up on the top end?

Thanks. . .

John P.

 

That’s just what vigs do, they just shoot u off the line. i think the efficiency is 94%. if you get a TC that has a higher efficiency then you will MPH faster.

Drew

 

You guys are accurate on your less efficiency theory depending on the converter of course, but you more than likely lost your trap mph because of the swap to the ET streets. The rolling resistance kills the mph. That's my theory. I hope this helps.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by TXCAMSS:
<strong> You guys are accurate on your less efficiency theory depending on the converter of course, but you more than likely lost your trap mph because of the swap to the ET streets. The rolling resistance kills the mph. That's my theory. I hope this helps. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">---------------------

Hmmm. . . well, I'll test out the theory that the E.T. streets were the culprit on March 15th at the next track event here. I have a new set of Nittos on the car now and the ET streets are on an extra set of wheels. I'll run the Nittos next time out and see if that makes a difference. I will have the Jet Hot LT headers on by then tho, so will be another week before I can go back again with the ET streets using the same setup for a direct comparison.

This is all really kind of academic, as I will soon be doing some engine work that'll step the HP & TQ up to a whole new game.(stroker crate motor) It will be interesting to see what happens in the mean time with different tires though.

Thanks for the replies, and apparently there must be a trade off from the launch improvement vs. the top end looseness and a guy has to live with it??

John P.

 

The stall combined with the ET streets hurt your mph <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

You can run a manual lockup switch at the track (Lock up the converter when you hit third gear)

Good luck,
Chris

 

ET streets hurt your mph? wow thats cool to know, kinda. i borrowed my friends ET streets and gain 2 mph w/ the addition of one mod. i knew they hurt me b/c i couldnt launch well at all. best 60 was the same as my street tires.... sad yes. Man i need a converter! anyway that makes me happier w/ my times, and the next time out ill get some nittos.

Drew

 

I doubt if the ET Streets are the reason you lost MPH. More than likely your problem is proper tuning. You also did not mention at what RPM your car is shifting, that also could be part of the problem. Your tranny will not lock up when you are at WOT, your tranny will not lock up at WOT unless you install a manual lock up switch. I hope this helps.

98 A4 C5
Donaldson Blackwing, Cartek Stage 2 Heads and Cam,
LS6 Intake, TPIS LT Headers, Underdrive Pulley,
Comp Push Rods, Rev 1116 Dual Springs, Borla Exhaust, 172 t.stat, LS1 Edit Tuning, ST3500
3.73 Gears, B&M 28,000 Trans Cooler, Hurst Line Lock. 383 RWHP/413 RWTQ (thru 3.73 Gears and Stock Cats) CCW Drag Setup with ET. Streets

<small>[ March 06, 2003, 02:11 PM: Message edited by: purple bandit ]</small>

 

What was said above covers it pretty good.
If someone in LV has LS1 Edit, you try to eliminate the "Torque Management" out of the PCM. <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by purple bandit:
<strong> I doubt if the ET Streets are the reason you lost MPH. More than likely your problem is proper tuning. You also did not mention at what RPM your car is shifting, that also could be part of the problem. Your tranny will not lock up when you are at WOT, your tranny will not lock up at WOT unless you install a manual lock up switch. I hope this helps. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">---------------------

Okay, I didn't mention specifically what rpm my car shifts at WOT, but since the PCM is untouched from factory settings I think the shift points @ WOT are 5750, someone correct me if I'm wrong on that. (the stock tach is so sluggish, it's hard to tell) <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

I'll talk to the guy who installed the converter and see about that manual lockup switch for 3rd gear @ WOT, maybe that's the answer. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

As far as deleting the dreaded TQ Management <img border="0" title="" alt="[Frown]" src="gr_sad.gif" /> w/LS1 Edit, would that make an aftermarket converter do anything differently? Does anyone know if LS1 Edit can program the trans other than with the stock converter? I mean, is it possible that someone with lots of experience using LS1 Edit could actually make the aftermarket converter lock up @ WOT in a given gear, at a certain RPM or speed? I'm not familiar with what that program will or will not do. Anyone know?

Thanks for the replies, I appreciate them. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

John P.

 

Put the drag radials back on. Unless your track is really bad you do not need ET streets at your mod level.

check your shift points too.

Your rebuilt tranny may suck down some power until fully broken in too.

Keep looking, unless there is a defect, a Vig 3200 should not cost you more than about 1 mph.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ChevyGoldfinger:
Hmmm. . . well, I'll test out the theory that the E.T. streets were the culprit on March 15th at the next track event here. I have a new set of Nittos on the car now and the ET streets are on an extra set of wheels. I'll run the Nittos next time out and see if that makes a difference. I will have the Jet Hot LT headers on by then tho, so will be another week before I can go back again with the ET streets using the same setup for a direct comparison.

[/QB]</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">For the best comparison, you'll want to run the same day. If you have the ETs on spare rims, perhaps a friend can bring them to the track for you. You can make a few runs on the DRs, then make some on the ETs. If you run a week later, besides having headers on, there will more than likely be a difference from the weather. That'll make it tough to determine the change from just the tire change.

 

Im betting the ET streets are the probably. Its no reason why you cant hook on nittos or BFG's are 18-20PSI. I wouldnt use et streets unless the track is crappy(but i'd run 24psi in them at that).

I dont see where you need any tuning since you only have bolt ons <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

as far as TM, I dont think thats gonna cost you any more than 1mph if that

try the nittos and see how they do

 

Also, if you spin off the line you will typically have a higher MPH.... The new lower 60 with the ET Streets would be a cause

 

I have first hand experience with this as well, plus where I race (LACR) is at a similar elevation to LVMS. I have run at both, back-to-back. The 26/11.5/16 are not good for you, you should try 26/10.5/16. I have seen the extra width kill MPH by about 1-1.5 MPH. The 10.5 ET Streets are more similar in diameter to the OEM tires, try that if possible ... or DRs. I usually launch at 3000 rpms with ET Streets. Also, typically with a better 60' you will trap higher. You should be 60'ing in the low 1.7s, not mid 1.8s. Reason for higher MPH with a better 60' is the vehicle is 'launched' hard forward in less distance, thereby utilizing the whole track for making MPH. Where as if you spin, you are effectively shortening the length of the track, so rather than running a 1320', you'll have only ran a 1000' track. Less distance to make MPH.

Oh, and with the headers (at LVMS) you should be at 12.7s at 105-106. That is what I ran when I had LTs at LACR. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> Good luck!

<small>[ March 20, 2003, 09:39 AM: Message edited by: MRZ28HO ]</small>