Discussion
I have just joined a long line of the converted after a rolling road session at Power Engineering with Mark Adams. Mark as ever was courteous and professional but more than that managed to get my Chimaera 400 running sweetly throughout the rev range. Previously it had plenty of power at the top end but was jerky below 2000 rpm and was not pleasant to drive unless you ragged it. Now it is smooth and producing up to 12-14 bhp and 20lb/ft of torque from 2000 rpm onwards. Peak power increased by 5 bhp but it was the gains lower down which make the difference. Final figures were 229bhp @ 5333 and 261lb/ft @ 3850. Not bad for a 4 litre. However I have got a Piper 272 cam fitted which may have helped and I had my injectors cleaned and a couple replaced.
However after all the improvements took it for a short test drive and whilst doing a 3 point turn to return it broke a rear shock! Arrrrgggghhhh.
However after all the improvements took it for a short test drive and whilst doing a 3 point turn to return it broke a rear shock! Arrrrgggghhhh.
It doesn't have any mods other than the cam which I put in because the old one had dished it's followers slightly. Compressions were ok @ 160 psi but not top of the range so I have to say I'm not entirely sure why. The makers of the cam claim an extra 20-24 bhp versus the standard Rover Cam but I didn't have a baseline for it's performance vs the TVR cam (It was a KV51). The 272 (Recommended for this engine by Chris Crane of RPi engineering)doesn't have massive lift but does have significantly more duration than the standard Rover cam and it does work well but only after Mark had remapped the fuel as it ran fairly roughly prior to this.
www.pistonheads.com/gassing/topic.asp?t=24511&f=9&h=0
Good to chat with you and your friend
Hope the shock gets fixed soon. J
Scoobysnack
Nice Griff with the cleanest manifolds I've ever seen. What did you get in terms of improvements in the end, unfortunately we had to go before your session finished otherwise we would have hung around to see how you got on.
Mr Freefall
I fitted the cam myself, took a couple of days of swearing so I'm afraid I can't recommend anywhere. If you do have it done make sure you get the followers changed and that the pre load is checked. However I think it sounds like changing the trumpet stack is the most cost effective increase. The standard stack is tuned for Range Rover torque requirements. I was sorely tempted to get a carbon fibre stack from ACT prior to the session but ran out of cash. I'm pretty sure if I had stretched the budget I might have seen 5-10 bhp and 10-15lb/ft more, still one for next time.
Nice Griff with the cleanest manifolds I've ever seen. What did you get in terms of improvements in the end, unfortunately we had to go before your session finished otherwise we would have hung around to see how you got on.
Mr Freefall
I fitted the cam myself, took a couple of days of swearing so I'm afraid I can't recommend anywhere. If you do have it done make sure you get the followers changed and that the pre load is checked. However I think it sounds like changing the trumpet stack is the most cost effective increase. The standard stack is tuned for Range Rover torque requirements. I was sorely tempted to get a carbon fibre stack from ACT prior to the session but ran out of cash. I'm pretty sure if I had stretched the budget I might have seen 5-10 bhp and 10-15lb/ft more, still one for next time.
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