water pump question
Discussion
Hi all,i'd like to try and get to the bottom of a little cooling issue with my car,and wondered if my symptoms are normal AJP behaviour or not.I have noticed that my coolant will run cooler if i run at 3k revs as opposed to running at 2k revs,in all gears.Normally i would put such behaviour down to a weak water pump,but as i'm not familiar with the behaviour of this engine i wondered if this is typical in a Cerb?TIA,Mike
I discussed this one at length with Dave Walker at Emerald. They run very retarded ignition timing on part throttle at below 3k rpm which makes then tend to run rather warm in that area. Having run an emerald for a while I can see why. If you advance the ignition in that area the 4.5 kangaroo hops like crazy sending shock waves up the power train. Its intake lengths have a nasty resonance that causes mixture reversion in the 1600-2600RPM /2%-4% throttle range. The lengths are good for mid to higher revs and I reckon that having the runners criss cross the top of the engine was an attempt to reduce this reversion problem, slightly at the expense of top end power. With the shorter intake pipes the problem got worse on mine but overall power increased significantly and a little play with the timing got rid of the problem, although the overrun fireworks are now even more impressive and I had to bring in the fans more agrssively to control the heat when stuck in crawling traffic. The TVR cure was to pull all the advance out of the bottom load lines of the map and after much playing around it is the only cure. It forces the cruise throttle angle to be slightly wider by reducing the power at very low revs which you compensate for with a bit more right foot. This gets it nicely out of the reversion area. The over run pops and bangs and the warm running are a consequence of it. Normal and nothing to worry about, just a characteristic of the engine, its intake tuning and ECU map.
Jon
Jon
fatjon said:
I discussed this one at length with Dave Walker at Emerald. They run very retarded ignition timing on part throttle at below 3k rpm which makes then tend to run rather warm in that area. Having run an emerald for a while I can see why. If you advance the ignition in that area the 4.5 kangaroo hops like crazy sending shock waves up the power train. Its intake lengths have a nasty resonance that causes mixture reversion in the 1600-2600RPM /2%-4% throttle range. The lengths are good for mid to higher revs and I reckon that having the runners criss cross the top of the engine was an attempt to reduce this reversion problem, slightly at the expense of top end power. With the shorter intake pipes the problem got worse on mine but overall power increased significantly and a little play with the timing got rid of the problem, although the overrun fireworks are now even more impressive and I had to bring in the fans more agrssively to control the heat when stuck in crawling traffic. The TVR cure was to pull all the advance out of the bottom load lines of the map and after much playing around it is the only cure. It forces the cruise throttle angle to be slightly wider by reducing the power at very low revs which you compensate for with a bit more right foot. This gets it nicely out of the reversion area. The over run pops and bangs and the warm running are a consequence of it. Normal and nothing to worry about, just a characteristic of the engine, its intake tuning and ECU map.
Jon
Fabulous explanation that makes a lot of sense,thanks very much JonJon
.I have the short induction on mine,currently running an MBE,but will be fitting a plug and play Emerald very soon-looks to be a great bit of kit
I used to run an Omex ecu on my last Griff,and i'm really looking forward to being able to map the ecu again Gassing Station | Cerbera | Top of Page | What's New | My Stuff