Notice on the new turbo how...
Notice on the new turbo how the bell gently tapers without any sharp edges leading to the 58mm billet compressor wheel. The original turbo is said to flow about 550 cfm while the new Precision Turbo is reported to flow well over 800+ cfm.
Next up on our test quest was to exchange our throttle body for a ported stock unit from Jose Motor Sports. While working on the induction we would remove the plenum "hat'' (aka doghouse) and install an RJC Racing Airflow Distribution Power Plate. The RJC ADPP has proven, after extensive research and testing, to evenly distribute and maximize airflow to all the cylinders through the lower intake manifold. This enables the Power Plate to eliminate low airflow to the front cylinders, which notably cause lean knock timing retard conditions. It's a well-proven performer used by many of the fastest Turbo Buicks. Jose Torres (Jose Motor Sports) has high regards for the RJC Racing ADPP-he uses one on his 9-second ride (March '08) and mentioned we'll love the results. And we did. On our test loop, after installing the ADPP and ported throttle body, we felt better throttle response and a noticeable power increase.
Unfortunately, the next day on our ride to Tune Time we felt slippage in First and Second gear. Good thing dyno testing is done in the gear with a 1:1 ratio (Third gear in a 200-4R). The RJC ADPP lived up to its reputation, and we were impressed to learn that we picked up 15 hp (without any knock retard issues). This enabled us to add more timing (4 degrees) and fuel (10 percent) to gain another 7 rwhp. Now the A/F was at a safe 11.8 to 11.9:1 This was great considering our previously lean A/F conditions. At that point we left the new tune alone, thanked the Tune Time guys for all the dyno testing, and drove home.
In a perfect world we could have strip-tested the results from the new turbo, boost controller, bigger downpipe, and power plate, but in this real world the transmission went south, slipping away. We missed our track test day, but felt the Buick could have dipped into the 12s. Once the transmission is rebuilt and teamed-up with the right stall speed converter, we'll get to see what a gain of 117 rwhp and 190 lb-ft of torque is worth from the bone stock baseline (14.25 at 94.53 mph). Hopefully, the over-100,000-mile Buick V-6 motor continues to survive the added boost and the host of bolt-ons. Stay tuned.
| DYNO AND STRIP TEST RESULTS |
| MODS |
HP |
TQ |
60-FT |
E.T. |
MPH |
| Stock 13 psi |
208@4,000 |
256@3,000 |
2.10 |
14.25 |
94.53 |
| Chip |
210@4,000 |
320@3,000 |
|
| Valvesprings, fuel pump |
238@4,100 |
358@3,000 |
| 42-lb injectors, chip, 19 psi |
240@4,000 |
405@3,000 |
2.10 |
13.63 |
100.55 |
| High-flow exhaust, 19 psi |
276@4,000 |
440@3,000 |
|
| Turbo (larger) |
303@4,500 |
440@3,500 |
2.31 |
13.50 |
104.68 |
| 3" downpipe, boost controller |
303@4,500 |
450@3,000 |
|
| ADPP, ported TB |
325@4,500 |
446@3,000 |
No strip test, bad trans |
|
| TOTAL GAINS FROM STOCK: 117 RWHP, 190 LB-FT |
In all fairness to dyno testing...
In all fairness to dyno testing these turbos-we removed the stock exhaust elbow / internal wastegate housing and installed it on the new turbo.
Don't do this when stepping...
Don't do this when stepping up to a larger turbo. A larger turbo will need a larger downpipe to perform properly.
Our new Precision Turbo easily...
Our new Precision Turbo easily bolted right in place where the original turbo once resided. The exhaust elbow housing and 2.5-inch downpipe proved restrictive towards spool-up. On our testdrive we felt more power from the new, larger turbo. It definitely hit harder, but was taking longer to spool up-a problem we intend to fix soon enough.
At Tune Time Performance we...
At Tune Time Performance we learned the larger turbo developed 25 more rwhp. Both peak torque and horsepower occurred at 500 rpm higher due to the added turbo lag. Since we began dyno testing this Buick, we've had 3-6 degrees of knock retard on every pull. It didn't matter if we adjusted the air/fuel mixture ratio to be safe (11.3 to 12.0) and if there was 110 octane race fuel in the tank.
For these pulls we started...
For these pulls we started out with a dangerous 12.6:1 mixture. Before the next couple of pulls Matt Hauffe (Tune Time's owner) programmed more fuel into the mix for a safe 11.8:1. We should have seen more power, but the knock retard was working against us. We'll also address the knock issue.
With total gains of 35 lb-ft...
With total gains of 35 lb-ft of torque and 63 rwhp from the new Precision Turbo and Pypes exhaust (Part 2) we expected e.t.'s to drop by roughly a half a second. Unfortunately, bad summer air slowed us by a few tenths and turbo lag didn't mix with the stock torque converter. Due to disappointing 2.3-sec. 60-foot times (previously 2.1), the e.t. only dropped by a tenth (13.60s to 13.50s). Again, we could only launch with 0-1 psi of boost even with our go pedal to the floor while power-braking (TR's launch better at 4-5 psi). With gains of over 4 mph in trap speed, we needed to reduce turbo lag for lower e.t.'s and support our power gains for the next test day at Englishtown.