I've been waiting for the timing data from the Thunderball to become available so I can give accurate results..............
As Trev said above,we are using a borrowed engine(I must say a big THANKYOU to Tim Jackson)which has hypereutectic pistons.both of the above meant we couldn't use a lot of nitrous...........
The Spider plate arrived Wednesday and was eagerly unpacked...........
What a superb looking bit of kit!!! And, a lot smaller than I had imagined.
We arrived at the track on Thursday afternoon and set about fitting the plate.All that was required was remove the existing 2" carb spacer and replace it with the Spider.Problem #1,the 2" spacer is in fact a std holley to dominator pattern adapter.No problem we thought,the Spider can sit between the "spacer" & the carb.Problem #2, this positioned the "distribution head" of the Spider IN the 2" spacer
All was resolved after a couple of calls to Trev for instructions how to bend the tubes down enough to point into the manifold runners.
The rest of the fitting was a piece of cake
All nitrous runs were done with 160/160 jetting(2 pairs)
QUALIFYING:
Run # 1: No nitrous pass : 10.002 @ 133.48mph
Run # 2: No delay,50% start, ramp 1sec. : 10.626 @ 142.94mph. The car lit the tyres IMMEDIATELY on launch!
Run # 3: No delay,25% start, ramp 1sec. : 10.001 @ 144.68mph. The car lit the tyres approx 3ft from launch!
Run # 4: 1sec delay,25% start, ramp 2 sec. : 9.470 @ 144.85mph. Ian said he could not feel the nitrous hit at all!
Run # 5: 0.7sec delay,25% start, ramp 1.5sec: 9.367 @ 145.73mph.
Ian still cannot feel the nitrous hit.
run # 6: 0.7sec delay,25% start, ramp 1.0 sec: 9.401 @ 142.48mph.
Although the car was quicker to 990ft it went very rich towards the top of the track,I suspect that the mid afternoon air was to blame!
Run # 7: 0.5sec delay,25% start, ramp 0.7 sec: 9.484 @ 143.75mph.
The car "turned" the tyres around 50-60ft from the start.
ELIMINATIONS:
Round # 1: 0.6sec delay,25% start, ramp 0.9 sec: 9.302 @ 142.86mph.
We put 1 degree of timing back in and dropped the fuel pressure 0.5lb to try to combat the "afternoon air"
CONCLUSIONS:
We used 1.25lbs of nitrous every pass(this includes connecting /disconnecting and purging)(actual engine usage would be @1lb)
I feel that a 0.7second improvement on a 10.0 second car is a huge leap considering the small doses we were using.
The launch & 60ft times could be improved with some suspension changes,
I suspect we cannot "hit" the tyres hard enough to get full weight transfer.
To get the most from this setup would also require the gearing to be lowered,it is currently geared for 170mph+ terminal speeds and runs about 110mph in first gear!
If this engine had forged pistons I think that times in the 8.50-8.60s would not be out of the question with nitrous usages around 3.5lbs per run.
Brain.