The Tufts Z28 Twin Turbo Page

This page is an ongoing diary of the Tufts Twin Turbo Project and what we are doing to build a twin turbo 1989 Camaro. The IROC has a smallblock chevy 350 cu. in. TPI engine that is currently putting out 320 hp. With the turbo, I expect at least 450 hp at 8 lbs of boost and over 750 hp when the engine is built to take 15-25 lbs of boost.

This is an accepted official design project (ME 93) as part of my mechanical engineering education at Tufts University. Some of the requirements are genuine academic achievements, along with the experience of organizing a complete project. Here are some of my ideas:

Analyze the engine and determine efficiency and horsepower before and after the twin turbos are installed
Determine how much power the engine can safely produce without breaking. This includes determining the cylinder pressures, autoignition points (detonation/knocking), compression ratios, strength of materials in the engine, forces on engine components etc...
Design the most efficient twin turbocharged exhaust and intake as possible. Possibilities are scavenging headers, harmonic ram air induction (runner length backpressure pulses force more air into heads) An intercooler might be a part of this.
Do a cost/benefit analysis for this project.

The educational portion of the project has been completed, and now the challenge continues. I am happy to announce that I received an A for this project. Countless people have helped in the project with advice and experience. Job Spetter from Turbo People in Hastings, NY, Mark Hamill from Accel/DFI, Mike Zoner from Callaway Cars, and the staff at Turbonetics have been invaluable in the design phase of this project, and Professor William Crochetiere at Tufts University assisted with my endless questions regarding electronics and the Tufts Mechanical Engineering Department. Thank you to all the sponsors who donated parts and offered a discount. Thanks to everyone that helped.

The basic turbo setup is complete, but the modifications continue. All the weak points are being found and better replacements are being installed. The 26 spline axles in the factory 10 bolt snapped in November 2000, so the rear was replaced with a 35 spline spooled Ford 9" from Moser Engineering. The Dynotech 3" Al driveshaft bent, and then later the 1LE Aluminum Driveshaft was torn in half, so at least I know the new rear and McLeod Street Twin clutch is holding. During the winter of 2000, the front mount intercooler was completed, which included a new tubular front bumper. The best timeslip so far is 12.82@113 on an 80 degree day with 5 psi boost on the factory L98. I plan on raising the boost to 10 psi soon. Future plans are for a detonation-proof 355. 98+ LS1 front brakes are being installed as well as the Herb Adams decoupled torque arm. I will try to get a dyno run before the L98 dies a spectacular death. Keep watching the website for updates. We are averaging almost 100 hits a day to the website. There is plenty here to read, and if you have any questions left, please ask.

Magazine Coverage!!!
The Z28tt website was mentioned in the December 2002 Issue of Popular Hot Rodding Magazine letters section. Thanks for writing in!

High Tech Performance Magazine featured the Z28TT website in the Cyber Cruisin' column in the March 1998 issue. Check out our review! (published with permission of High Tech Performance) Website of the Month!!! We've been featured in James O'Reilly's Camaro Website. This is one of the best looking Camaro sites I've seen. professional artwork, and the layout is simple, yet very elegant. Take a look!

8/11/04 - Summer Update It's been quite a while since the last update! The separate electrical ECM panel is complete. When we went to fire up the new engine, we did not get a reliable spark, which tested out to only be 5,000 volts (should have been 40,000 volts). Even though the coil tested fine according to the service manual procedures, it was replaced and all was well. The next issue was low oil pressure, even with 15W50 break-in oil. We changed the smallish Bosch filter for a large Fram HP4 racing filter, and pressure jumped 15 psi. The small filter may have gotten clogged with the Redline break-in grease. The Fram was replaced with a Wix 51062R racing filter and Mobil One 15W40 oil after the break-in was complete at the National F-body Event at Indianapolis Raceway Park this June. We attempted to tune the air/fuel on the track, but it was much easier with a few miles of street driving. Once the tune was in the ballpark, the Z28tt could actually be raced! It was down since November of '01 from the wiring meltdown at LimeRock, and now finally running. Life is good.

After the NFME event at IRP, there was an EMRA time trials on the Pocono North course, using one of the banked NASCAR turns. The Z28tt handled pretty well with the 950 lb front springs, 175 lb rear springs and Koni Yellows, and was slightly tail happy, so I'll change down to a smaller 21mm rear swaybar from the current 24mm bar. There is the 36mm hollow front bar on there right now, and tires are old Kumho Victoracers (315's in the rear and 275's up front). I did manage to get the 2nd fastest time of the day, a 1:01.71, so I left home happy. The new issues with the extra cornering is that I was getting oil starvation on all right hand corners, as well as oil overheating (pegged the 300 deg Autometer gauge, so it was in the 340 degF range). I added an 3qt Accusump to the oiling system (I already have a Canton pan), mounted behind the dash, a CM remote oil filter, and a TruCool oil cooler between the radiator and intercooler. We'll see how that works out at Watkins Glen next month.

This past weekend I loaded up the Z28tt, and headed down to Durham, NC to visit Jeff, John, and Pat at Carolina Auto Masters for some dyno tuning. Over 2 days, we managed to get 20 runs in, and played with various combinations. The existing tune was decent, but very conservative on the timing (24 deg at 5 psi), so we bumped that to 27 deg, and then again to 30 deg (not much change over 27 deg). Afterwards, we made a $1 boost controller with some brass barb fittings, a tee, and a small ball valve. At 5 psi, we got 414 rwhp and 450 rwtq. The boost was turned up to 12 psi, and we got 447/536. Unfortunately the boost started dropping off after 4k, possibly showing how restrictive the 2.5" downpipes and 3" catback were. Just for curiousity, we disconnected the wastegates completely. The boost climbed to 17 psi, and then the spark was blown out by 3800 rpms. I guess the stock HEI ignition (new plugs & .034 gap) just couldn't keep it lit. We did get 537/590 at 3800 rpms, though! I have the Accel 300+ wired in already, and will disconnect the catback exhaust the next time I take the Z28tt to the dyno. The guys at CAM were a big help getting all the testing done in just 2 evenings.

Finally, I stopped at Muscle Motor Parts in Huntersville, NC to pick up a NASCAR exhaust, with the flat side pipes (boom tubes). This will be fabricated into a 3" dual exhaust, from the turbos back, most likely this winter, and should take care of the backpressure problem.


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