Well it's been 4 years since the new engine was fired up, and I can't believe it's taken me that long to finally throw it down the 1/4 mile! Been talking about it for ages, wondering what times it might run. So on Sunday just gone, I finally made the trek up to Heathcote in the old girl, and damn it was good to get back on the track
I sold off my MT ET Street Radials a long time ago, and can't justify the cash these days for race tyres, so Sunday was old school racing in pure street trim, on the good old cheapo Maxxis street tyres - which I really wasn't sure what to expect grip-wise.
I was really, really curious to compare this engine combo with my previous ones. My old 383 with the hyd flat tappet, 4-into-1's, twin 3" system, ET Street Radials, and making 245rwkw - did a best ever of 11.77 @ 115MPH.
This new 381 is well down on overall HP (it makes 230rwkw) which works out to be 30 Flywheel HP less (peak). I'm also now running the much smaller exhaust (little Tri-Y's, with twin 2.5" system).
The rest of my setup has remained consistent from what I first bought 15 years ago (ie. the RPM Air-Gap dual plane, old Pro-Topline iron heads, the 3200 stall, and 3.7 gears. Similar comp, 750 carb etc. The main change is clearly the hyrdo roller camshaft.
I was absolutely convinced in my mind that with the lower power and more restrictive exhaust that I'd be running mid 12's (really hoping for low 12's). The only change I made after arriving at the track was playing with the tyre pressures.
So my long anticipated results:
First pass - 12.19 @ 115 MPH. Wheelspin, and skating when hitting 2nd gear too. It was great to be back on the race track though!! Instant smiles. Lousy 60 foot time of 1.99. 26 PSI in the tyres.
Second pass - 12.04 @ 114 MPH. 1.85 60 foot, with 23 PSI. A slightly better run.
I started thinking surely there's an 11 hiding here somewhere. Maybe I'm not back in the 12 second club after all. It was taking me a little bit to get the feel back after so long out of the seat, so I manned up and dig a bigger burnout, then hit it harder off the line... come on Maxxis you good things you!!!!.....
Third pass - 11.87 @ 115 MPH. 60 foot a bit better again at 1.78. Wasn't expecting that! Tyre pressure drop to 20 PSI was a good one.
Fourth pass - completely fried the tyres, 12.6. Instant memories of why street tyres are so frustrating at the strip, lack of consistency.
Fifth pass - 11.82 @ 116 MPH. 60 foot 1.76. Nicer pass. Shifting at 6,500, crossing the line around 6,200 / 6,300 or thereabouts.
I was pretty stoked with that one - knocking on the door of 11.7's, which is where my P.B. is still stuck, haha!!. My 60 foot times are not good though - I've run 1.62 in the past. I reckon there's still more in my car if I can launch it better. Need a bit more practice and more runs to get back into the zone. I'm now keen to see how far I can push these street tyres.
Question - what's the lowest PSI you can run in a normal street tyre?
The rest of the day at Heathcote was written off pretty quickly - took a passenger and ran an 11.9, the the missus had a steer and did a couple of 13.1's frying the tyres. All of a sudden it was 4pm and track was closed. Jumped back in the Torrie and drove 2 hours home again, it didn't skip a beat. Absolutely rapt! I'm really loving this combo. The tru-trac diff centre proved to be a winner too.
Already itching to go again
Eric in the triple carb'd 6 cylinder LJ was running into the 13's:
This is my future pit-crew! Kids are now 6, 3, and 6 months old:
Father in law's supercharged V6 behind me:
Lots of cool cars were out to play at Heathcote:
Taking my sister for a fang...