kiggly
Supporting Vendor
- 321
- 198
- Feb 17, 2003
-
Ann Arbor,
Michigan
I recently dug the trailer out from under the snow and dragged the race car to the local dynojet for a few pulls on the tired old motor. This is the same engine that has been in it all last season and it has absolutely terrible blowby. The top ring doesnt seal until the piston is about ½ down the cylinder, so Im sure that hurts power. The only change since the 8.55 pass is a different intake cam that has higher lift (14mm) and is a MIVEC cam so I can make timing adjustments on the fly. Duration is very similar.
A couple things to note for all these pulls this car is an auto and that is an additional 15-18% loss compared to the 5-spd, all pulls above 40psi were at 11.1-11.3:1 AFRs, timing is just over 10deg.
As the tune was getting sorted out the first stable-boost pull was 34psi and 647whp. The next pull at 41psi the car bounced a little on the rollers and it peaked at 735whp, but a more realistic call would be more like 720whp. The next pull was at 45psi and it delivered 751whp peaking at about 8000rpm just as it got on the converter, then falling to about 650-660whp at 8800rpm. These pulls were with the intake cam adjusted the same as the way it ran the 8.55 pass with 43psi boost.
About 720whp
Pull 751whp
Backpressure at 45psi was about 34psi and turbo speed was about 103,000rpm. This is a 74mm BW turbo with a 1.25AR turbine housing. I was really happy to see I was still in the turbo map and there is room to grow.
A couple pulls and some cam timing tuning later boost was down to 42.5psi. Peak power was 784whp at about 8400rpm and held to about 720-730whp at 8700rpm. I was VERY happy to see this. Next pull repeated the 784whp number, but something went wrong at about 8300rpm.
Pull 784whp
We chased this stupid misfire for the next few pulls, eventually changing back to exactly how it made the 784whp but with fresh plugs at a smaller gap. After it didnt run clean there, we gave up and pulled it off the rollers. The misfire turned out to be a vacuum hose off the BOV feed, nothing was actually hurt.
It is really good to see there was some potential left in the old parts combo. The new parts for next season should make a bunch more power. Here is video of a couple pulls. Right-click, save as:
Dyno Video
Kevin
A couple things to note for all these pulls this car is an auto and that is an additional 15-18% loss compared to the 5-spd, all pulls above 40psi were at 11.1-11.3:1 AFRs, timing is just over 10deg.
As the tune was getting sorted out the first stable-boost pull was 34psi and 647whp. The next pull at 41psi the car bounced a little on the rollers and it peaked at 735whp, but a more realistic call would be more like 720whp. The next pull was at 45psi and it delivered 751whp peaking at about 8000rpm just as it got on the converter, then falling to about 650-660whp at 8800rpm. These pulls were with the intake cam adjusted the same as the way it ran the 8.55 pass with 43psi boost.
About 720whp
Pull 751whp
Backpressure at 45psi was about 34psi and turbo speed was about 103,000rpm. This is a 74mm BW turbo with a 1.25AR turbine housing. I was really happy to see I was still in the turbo map and there is room to grow.
A couple pulls and some cam timing tuning later boost was down to 42.5psi. Peak power was 784whp at about 8400rpm and held to about 720-730whp at 8700rpm. I was VERY happy to see this. Next pull repeated the 784whp number, but something went wrong at about 8300rpm.
Pull 784whp
We chased this stupid misfire for the next few pulls, eventually changing back to exactly how it made the 784whp but with fresh plugs at a smaller gap. After it didnt run clean there, we gave up and pulled it off the rollers. The misfire turned out to be a vacuum hose off the BOV feed, nothing was actually hurt.
It is really good to see there was some potential left in the old parts combo. The new parts for next season should make a bunch more power. Here is video of a couple pulls. Right-click, save as:
Dyno Video
Kevin
