Stall Tactics

In our last episode involving this brazen Bird, owner Melvin Benzaquen recorded 12.4 ETs at 112 mph with his Vortech-supercharged '99 Firehawk. And although he was elated with the Pontiac's newfound performance boost, he knew as well as we did that the stock torque converter's 1800-rpm stall speed wasn't getting the blower spinning fast enough during launch. We figured that there could be a good four-tenths and three mph left in this combination with the right converter, so we jumped into action with a phone call to Yank Performance Converters. Yank turbines are held in high esteem with the F-body crowd, and after a couple of conversations with company owner Mike Senia, we were confident that our performance goals could be met. Once the Pro Yank 4100 Extreme arrived at Classic Restorations in Sloatsburg, N.Y., we journeyed up to document the installation. Bolting up the Yank unit proved very straightforward, and we only encountered a few snags all day. It may surprise some of you to see us connecting a 4100-stall converter to a street car, but the Yank unit retains the lock-up function, which helps preserve streetability despite the increased stall. Now let's turn some wrenches.

At The Track

Melvin was chomping at the bit to test his newest modification, so we hit Englishtown Raceway Park just days after the last bolt was tightened. Benzaquen's initial test drive on stock radials revealed gut-wrenching power and the kind of wheelspin that keeps tire companies in business, so we were interested to see if his 315mm BF Goodrich drag radials could curb the new converter's appetite. His first run was made at almost 11 a.m. with the tires at 25 psi and the motor spinning at three grand. We can hear Yank's Mike Senia laughing somewhere. Halfway down the track, the tires finally hooked up and Melvin proceeded to a 13 flat at 115 mph! Already the Hawk had gained three mph over the stock converter. Initial butterflies out of the way, Melvin hot-lapped the Bird and left at 2500. The 60-foot time dropped from 2.31 to 2.14, and "12.58" flashed at the big end. Previous testing of the Vortech-powered LS1 showed that several laps in a row didn't really hurt the Pontiac's mph, so he came back around for a third run. Leaving at 2200 this time, Melvin eased into the throttle to plant the big BFGs and went faster yet with a 12.35. The 60-foot time continued to drop, with a 2.0 recorded on this run. Was he finished? No way. Pulling up to the line after a smoky burnout, he brought the revs to 2200 again and walked the car out. A stellar (on drag radials) 1.9 60-foot was the result, and he continued on to a 12.30. At this point, his mph had dropped to 113 and change, so we parked the 'Hawk and discussed strategy. We decided to drop the tire pressure to 20 psi for the remaining runs, and Melvin would ease into the throttle as much as possible to keep the big tires from spinning. Forty-nine minutes later, Benzaquen heated the BFGs and staged, the eerily quiet LS1 turning 2200 rpm. When the lights came down, the tires squawked as he nailed a 1.81 60-foot time. As the 4L60E changed gears, there was enough traction to keep the wheels from spinning, and the Hawk started to fly. I about dropped the camera when I saw "11.86" on the board--he didn't just go 11.8, did he?

As Melvin parked the car, he was all smiles. It was just a matter of getting all of that power down, and that particular run was perfect. His trap speed of 116 marked a 4-mph improvement over the stock converter, and the car picked up almost six tenths, as well. Not bad for one day of labor! Undoutedly, slicks and a higher launch rpm would show further improvements but we don't want to grenade the stock rear just yet.--R.J.

About Yank Performance Converters

While considering options for this story, Melvin Benzaquen proposed, in no uncertain terms, a Yank torque converter. Visit any GM performance web site such as LS1.com and you will hear similar adulation toward Mike Senia and his Alma, Arkansas company. These transmission components have become the hot ticket for slushbox-equipped GM vehicles, and for good reason: Our 4100-stall Pro Yank Extreme converter (which lists for $995) came with six-bolt mounting lugs for improved durability, a lightweight billet cover, and a posi lock-up clutch with Kevlar linings. This last feature locks up the converter under torque loads of 475 lbs./ft. or more, a situation seen in nitrous- or blower-equipped motors. Obviously, this is a serious piece, and the fact that it is hand-built only adds to its appeal.

Rarely do you see a company this serious about performance skipping steps, and Yank is no different. The folks at Yank took the time to develop individual converter profiles on actual General Motors dynamometers, fine-tuning each converter for its specific application. Then they created their own software to match converters to various vehicles. Many of the components used in Yank converters are of their own design, such as the billet pieces manufactured exclusively for them by an outside source. And they never build more than one converter at a time. "Instead of building a bunch of units at once, we devote our full attention to building each one as well as we can," Mike explains. "I liken it to blueprinting an engine. You aren't going to buy a race motor from K-Mart, are you?"--R.J.

An Owner's View On Driveability

As I watched my Firehawk being lowered on the lift after installing the Yank 4100 stall converter, I was filled with both anticipation and trepidation. All the research done in finding the right stall speed converter had led me to this point.

Asking torque converter manufacturers, people in the hobby and at the track, and surfing the various message boards on the internet, I had learned how it works, the expected reduction in elapsed times and which torque converters performed and those that didn't. However, nowhere could I find any information on how the driveability of the car would be affected. Yes, I had heard the ramblings of various people about how bad the "big" converter drove. Had I ruined the driveability of my Firehawk? Was I going to have to rev the motor to 4000 rpm to get moving from a traffic light? These questions were about to be answered.

I started the engine--everything seemed to be normal. As I put the shifter into drive, I noticed there was no longer the familiar "lurch" that I had become accustomed to. I gave it some gas and felt movement around 1500 rpm. As the Hawk gained speed, the transmission would upshift in the 2500 rpm range at light throttle but felt markedly slushy. Gone were the positive upshifts that had been achieved at the dealer during the unforseen overhaul of the transmission earlier last year. They were replaced with a sensation that I can describe as a slipping transmission. Upon applying a little more throttle to raise the engine speed above 3000 rpm, the F-body came alive. Once I was up to 45 mph, the transmission shifted into overdrive and I was rewarded with the instantaneous feel of a positive engagement. Once lockup is achieved, one would never know that there was a high stall speed converter lurking beneath.

It takes some getting used to when driving around local streets at low speeds but I have found that applying an approximate 30% throttle seems to reduce some of the slushy feeling as the transmission shifts up through its gears. Initially I found myself anticipating reaching 45 mph plus to get into overdrive. After driving several hundred miles with the new converter, I find myself getting used to it. Would it act the same at the track?

Lining up in the burnout box, I put the shifter into first gear and gave it throttle. Once into the 3000 rpm range, I was able to do a good smokey burnout. I proceeded to the starting line and power braked to 3000 rpm as that is all the car would hold. The original converter would only allow 1800 rpm. On the last yellow light, I stabbed the throttle and felt the drag radials howl in protest as I spun halfway down the track. Obviously, there was a huge difference in how this Pontiac was to be launched. Once above 3000 rpm, the Hawk felt more powerful than it ever did before. A trip to the speed shop for slicks and a stronger rear axle setup are definitely going to be needed!

Is the reduced driveability worth the tradeoff for significantly reduced elapsed times and higher trap speeds? This Hawk went from a best of 12.46 at 112 mph with the Vortech setup alone to a best time of 11.86 at 115.99 mph with the Yank torque converter change. And this is in street trim. The answer for you is in how you intend to use your Pontiac. If it's a daily driver and a weekend racer, it would be a tough decision. In my case, the Hawk is mainly for weekend racing and some cruising, so it is a tradeoff that I can definitely live with!--Melvin Benzaquen