R31 Track/drag Car

[Nubblet]

A few years ago myself and my old man built this car. The original plan was to race it on the circuit, but dad was always too busy to put the time into putting in competitions. It's been complete for close to 2 years and has only seen the circuit twice, the first time with major clutch issues, the second time in the wet. It's seen the drag strip twice also, the first time also with the fail clutch, the second time after a replacement.

As you can see in the pictures, the inside of the car is completely stripped, custom dash with far too many gauges, full rollcage, 5 point harnesses and bucket seats. The car weighs roughly 1300kg and is sitting on 425hp at the wheels on a soft tune of 16psi. The engine completely rebuilt rb30 with forged internals, running a GT3540 turbo. The radiator is from Glen Seton's V8 supercar from...2004 i think. The huge brake calipers are also off a V8 supercar, but i forget exactly which one.

As of now its best 1/4 mile time is 12.7, this with some traction problems at the line. As the car is now, we should get it close to breaking the 11 second mark. Today we are installing a Greddy profec bspec2 electronic boost gauge, then we are going to set a lowboost of 17 psi, and a high boost of 20 psi. With this added power and a set of semi slick tyres we are hoping to get into the high to mid 11s at the drag strip tommorow.

[BezerkR32]

such a shame to waste such a beautiful car on the drag strip. bring it to the next SAU track day....you will love it and appreciatethe car so much more. FYI the car at 1300kg and 400hp should be good for mid 11s

[Nubblet]

such a shame to waste such a beautiful car on the drag strip. bring it to the next SAU track day....you will love it and appreciatethe car so much more. FYI the car at 1300kg and 400hp should be good for mid 11s

Yeah, with practice getting shift points right and managing traction, mid 11s for sure. We are putting a short shifter in when it arrives which should help a bit.

We didnt end up going to the drag strip, we came across some issues with the boost controller, and the clutch master cylinder is playing up too. We are getting it tuned properly on a dyno tommorow. I will be videoing it, so i will pop that on youtube tommorow arvo.

[cactus]

Yeah, with practice getting shift points right and managing traction, mid 11s for sure. We are putting a short shifter in when it arrives which should help a bit.

We didnt end up going to the drag strip, we came across some issues with the boost controller, and the clutch master cylinder is playing up too. We are getting it tuned properly on a dyno tommorow. I will be videoing it, so i will pop that on youtube tommorow arvo.

Dyno results?

[Nubblet]

Dyno results?

We've come across more problems. The boost controller is supposedly tuned, but we are losing power for some reason. Low boost is set to 18 psi, and high boost is set to 22 psi. The dyno sheet shows a nice high curve of power up to 4250 rpm, but after that the curve flattens totally. I'll attach an image of the dyno sheet. Hopefully someone has an idea of what could be causing this drop in power.

[BezerkR32]

what valve springs are in engine?

We've come across more problems. The boost controller is supposedly tuned, but we are losing power for some reason. Low boost is set to 18 psi, and high boost is set to 22 psi. The dyno sheet shows a nice high curve of power up to 4250 rpm, but after that the curve flattens totally. I'll attach an image of the dyno sheet. Hopefully someone has an idea of what could be causing this drop in power.

[SimonR32]

We've come across more problems. The boost controller is supposedly tuned, but we are losing power for some reason. Low boost is set to 18 psi, and high boost is set to 22 psi. The dyno sheet shows a nice high curve of power up to 4250 rpm, but after that the curve flattens totally. I'll attach an image of the dyno sheet. Hopefully someone has an idea of what could be causing this drop in power.

that looks pretty spot on to me... power builds strong as boost rises and then flattens off as it holds boost

im guessing your not used to looking at turbo power graphs?

[Nubblet]

that looks pretty spot on to me... power builds strong as boost rises and then flattens off as it holds boost

im guessing your not used to looking at turbo power graphs?

I've seen enough. And im not the only one who sees problems with what its doing. My old man, the tuners and a few mates ive spoken to think something is wrong. And does 420hp at 22 psi sound about right to you? the car was making 425hp at 16 psi before the boost controller change. The dyno sheet from its soft tune looked completely different, the curve was smoothe all the way to redline, there was no sharp drop in power as the rpm got higher.

[cactus]

The problem is getting a place such as Performance Unlimited (V8 specialists...) to tune a Jap motor.

I would be taking it to ovaboost or all-star. I'll be sure to tell your dad that tonight when I call him