Reapers Black VP SS

[Immortality]

I'm thinking dirty old imputant injectors and/or increased dead time due to voltages drop when his twin AU thermos kick in under load....L8r

you should be able to monitor the system voltage with one of the data logging pieces of software you have. even so, the ecu should be able to compensate for the extra loading.

might also pay to check the electrical system, battery connections/ leads/ earths etc. make sure there all clean and tight

 

[Reaper]

you should be able to monitor the system voltage with one of the data logging pieces of software you have. even so, the ecu should be able to compensate for the extra loading.

might also pay to check the electrical system, battery connections/ leads/ earths etc. make sure there all clean and tight

Yeah - electrics and ignition are actually in top shape. Injectors and fuel pump may well be the original items and never touched from new AFAIK. If I get home early enough tonight I'll spend an hour or so collecting data and keep track of when the thermos are on or not. (May even just pull the fuses for a bit).

Reaper

 

[thestig]

you should be able to monitor the system voltage with one of the data logging pieces of software you have. even so, the ecu should be able to compensate for the extra loading.

might also pay to check the electrical system, battery connections/ leads/ earths etc. make sure there all clean and tight

We could log system voltages from the ECU via ALDL, however the 808's nasty baud rate makes the info pretty much useless, it'd be better just to plug in a multimeter and read the numbers off that. Faster too

As for the ECU compensating for the voltage drop, I would agree that it should do so, but up to what point? After all the V8 isn't supposed to have a thermo fan at all, let alone a pair of them that need a 40amp fuse on their OEM install. On startup 1 fan draws well in excess of 20amps, and Reaper has 2 wired in Parallel.

Regardless, I'd say that the injectors are the most likely problem, but the dead time is something to watch out for if our AFR's become erratic.

L8r

 

[stocky]

maybe you need to speak to hakhawk about modifying the ECU to run a VR aldl which is much faster? i think thats what he did anyway

 

[Immortality]

We could log system voltages from the ECU via ALDL, however the 808's nasty baud rate makes the info pretty much useless, it'd be better just to plug in a multimeter and read the numbers off that. Faster too

As for the ECU compensating for the voltage drop, I would agree that it should do so, but up to what point? After all the V8 isn't supposed to have a thermo fan at all, let alone a pair of them that need a 40amp fuse on their OEM install. On startup 1 fan draws well in excess of 20amps, and Reaper has 2 wired in Parallel.

Regardless, I'd say that the injectors are the most likely problem, but the dead time is something to watch out for if our AFR's become erratic.

L8r

all good points, however if it is the thermos cycling i'd expect to see a spike when they cycle. reaper mentioned a linear change in AFR's. would suggest a struggling pump that letting pressure drop off.

yes startup current draw on electric motors spikes but should settle fairly quickly. the ecu should be able to compensate for full load on the alternator. still, with your new found toys it shouldn't take long to find the problem.

if the thermo's are causing a problem when they cycle. possibly consider that a large capacitor wired accross the thermofans. should reduce voltage fluctuations when they kick in (much like they use caps for large stereo systems)

 

[Reaper]

maybe you need to speak to hakhawk about modifying the ECU to run a VR aldl which is much faster? i think thats what he did anyway

Yeah have spoken to him about that. Probably a ton of effort for very little gain in my situation. It is on a long list of stuff to be done but is somewhat down in the priority list right now.

all good points, however if it is the thermos cycling i'd expect to see a spike when they cycle. reaper mentioned a linear change in AFR's. would suggest a struggling pump that letting pressure drop off.

anybody have a pressure guage to measure it???

yes startup current draw on electric motors spikes but should settle fairly quickly. the ecu should be able to compensate for full load on the alternator. still, with your new found toys it shouldn't take long to find the problem.

Current draw is around 18(ish) amps per fan at startup and then drops within a second to around 7.

if the thermo's are causing a problem when they cycle. possibly consider that a large capacitor wired accross the thermofans. should reduce voltage fluctuations when they kick in (much like they use caps for large stereo systems)

They do cycle fairly often as I have them keeping temps within a very narrow range. Thus, they kick in and then turn off quite often but I suspect even the headlights will draw more power.

Reaper

 

[greenfoam]

I doubt your fuel ratios are anything other than perfect considering the times it makes, why should perhaps the quickest bolt on 5 litre in the country be running 15:1 ?. Then again the show is almost all over for a 5 litre at 4500 rpm and being lean after that probably wouldn't hurt your times much but it doesn't show up on your power graph so I think something in the messuring is not quite right

 

[Reaper]

I doubt your fuel ratios are anything other than perfect considering the times it makes, why should perhaps the quickest bolt on 5 litre in the country be running 15:1 ?. Then again the show is almost all over for a 5 litre at 4500 rpm and being lean after that probably wouldn't hurt your times much but it doesn't show up on your power graph so I think something in the messuring is not quite right

Just spent an hour and a half collecting data and under load it's not quite as bad as first thought. We are running around 13.5:1 - 13.2:1 under 3600. 4000 - 5200 is a little better at 12.74 - 12.69:1. Enrichment seems low when I stomp the go pedal (or at best the lag is very slow - 1.5 sec or so) but I haven't looked into that just yet.

On cruise conditions with light load we are getting mid 14:1 - 15 up high

Reaper

 

[greenfoam]

Ok that sounds more like it , the enrichment should be instant, but you can probably help it along a bit by richening the F60 map along a line where it goes from 60 map to 100 when you boot it, I don't know if you will gain power under 3600 with 13:1 but you can try

 

[Reaper]

And yeah... IAT sucks
Need to find time to insulate the new bananas.

Reaper