I've been lucky enough to get hold of maps for other cars with identical engine specs to mine but they all seem to have 16 load and 16 rev bins so I am having to try and pick what load values/rev values to use.
With the load values for the TPS I notice that many others seem to have several load sites closely spaced at low% throttle openings then bigger gaps higher up, plus most seem to have the top load set at 78%. I assume from this that the mapping makes the biggest improvement at lower/partial throttle openings compared to distributor advance plus the map will be the same for all loads above 78% if that's the top load site and I guess that's o.k?
Similarly I'm curious to know what rev bands I should use. Is it more benefitial to try and make more sites lower down the rev range and fewer at the top end?
Should have mentioned it's a 1000cc Imp engine, full race head, R23 Race cam(loads of overlap and very peeky), twin 40s that revs to 9500rpm and doesn't make much power under 6000 rpm (hence the move to mapped ignition).
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Moderators: JeffC, rdoherty, stieg, brentp
I'm no engine tuner, but....
Probably better to have more sites at low rpm, high load so when you jump on the throttle you get the best rpm/sec increase possible and get on the cam quicker.
I'm surprised the TPS tops out at 78% - is that with an uncalibrated TPS? I would have thought it worth exploiting the 78% to 100% region.
Most maps only show minor increases in advance above 4000 rpm, so that's why the map sites can be wider at higher rpms - but you need to fine out what your engine needs/wants if you're revving from 6000 to 9500 (nice!)
Probably better to have more sites at low rpm, high load so when you jump on the throttle you get the best rpm/sec increase possible and get on the cam quicker.
I'm surprised the TPS tops out at 78% - is that with an uncalibrated TPS? I would have thought it worth exploiting the 78% to 100% region.
Most maps only show minor increases in advance above 4000 rpm, so that's why the map sites can be wider at higher rpms - but you need to fine out what your engine needs/wants if you're revving from 6000 to 9500 (nice!)
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fsmlittler
- Posts: 7
- Joined: Tue Jun 24, 2008 8:14 pm
Thanks Martin. You've pretty much confirmed my own thoughts but I'm still not sure whether the TPS loads sites should be linear or closer towards the bottom end.
I'd assumed the 78% top site was based on rolling road experience that indicated there was little difference between 78% and 100% throttle hence the weird load sites.
At the moment I've got 1000rpm increments starting from 500rpm and the load sites run in 10% increments starting with 0. Most others seem to have 3 or 4 sites before 20%.
I'd assumed the 78% top site was based on rolling road experience that indicated there was little difference between 78% and 100% throttle hence the weird load sites.
At the moment I've got 1000rpm increments starting from 500rpm and the load sites run in 10% increments starting with 0. Most others seem to have 3 or 4 sites before 20%.
From my experience, many throttle bodies tend to be sized in such a way so that they're not the restriction in the system- so it would seem the engine's volumetric efficiency would not change much in the last 20% or so of the throttle opening. That could be why your seeing minimal changes in the upper range of the load axis.