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Mapping question

devil84

devil84

Messages
983
Hi guys,

as some of you may know, the K100 group buy is coming to an end soon, and soon will come a point where I will need to discuss with the mapper regarding what i want out of the tune.

So I am armed with at least some knowledge before I am in that position, is there anything I need to know before this.

I am basically mapping my car to a intake, and a 60mm catback.

I want:

Good mid range gains
More BHP at the top end
But critically, also better fuel economy on a motorway run doing 65-70 for example. (My commute to work is on a motorway) Heard this was possible with a tune ( yes yes I know, I did not buy the ep3 for MPG..... )

Against that backdrop, what would I need to tell the mapper:

Set VTEC point a 4500? (what is a good point to set the VTEC???)
Increase the redline?

Anything else ?:)

Is that it?
 
Vtec is set at the optimal Point.
When the low cam starts to lose power and high cam starts to gain.

You can't predict/demand a vtec point really.

Mpg is all in the part throttle tuning.

Tell the mapper what you want. He will know best.
 
Being really honest bud a good mapper will map the car according to the mods on it.

The VTEC crossover point should always be set the where the high can starts making more power than the low cam.

Fueling is set to be optimal so as to maintain a good air to fuel ratio. This is why the car will be better on fuel after a map, because the standard ECU fuelling is rich and timing is safe for all the situations the car might be used in, i.e. altitudes/atmospheric pressures/fuel quality and so on. For example if you know you are always going to run the car on V-power and not be driving in the Himalayas the tuner maps the car based on what he/she is seeing that day.

The rev limiter is set according to your engine mods. For example you wouldn't rev a car with standard valve springs up to 9,000 rpm, and there isn't much point setting the limiter higher than say 8,400 or 8,600 if the power curve and torque are tailing off by then.

By all means mention what you want out of the tune to the mapper, it won't do any harm but the mapper does have to follow what the car is telling them.

Edit: did it really take me 8 minutes to write that?! :lol:

Stoo makes a good point about the part throttle. :)
 
How much difference would be noticed if the car was mapped to vpower over standard fuel? Would I notice it then using standard fuel? (when I have too)
 
If it's mapped on V-power you wouldn't want to then run it on standard fuel as you would run into issues with the engine knocking on the standard grade fuel.

There's no reason why you couldn't get it mapped on standard fuel to start with but the done thing is to use a higher octane like V-power to have it mapped on. How much extra you'd make is debatable but it will be more on a higher octane fuel.
 
I mapped mine on BP ultimate because it's 97 RON, so 95 isn't too far off and 99 is fine also.

I don't know much about it but I've heard of variable Vtec where the vtec point changed depending on throttle position. i.e. at part throttle vtec is 5800 and at full throttle it's at 4500. I would assume that is the most 'economical' set up?

I just have a 'standard' TDI map, 8600 rev limit and circa 4500rpm vtec point. If you don't ask for specifics that's pretty much what you'll get, tuned to your engine ofcourse.
 
Vtec has a 'window of operation'

An upper and lower threshold depending on Manifold absolute pressure.

Full throttle, vtec will engage at the lower end of the threshold. Say 4000rpm for example.

If your at part throttle however, vtec may not engage until the upper limit has been reached, say 6000 rpm.
 
As per what Stu says.

It's only I-VTEC engines that do this. Something like an S2000/DC2 that have a VTEC engine doesn't.
 
Bloody hell so many decision, now need to determine two vtec points lol.

Does this occur on A standard car then? This upper and lower limit.?

Cheers for info guys.
 
devil84 said:
Bloody hell so many decision, now need to determine two vtec points lol.

Does this occur on A standard car then? This upper and lower limit.?

Cheers for info guys.
Click to expand...

The lower point is where the high cam starts making more power than the low cam, so again it is something that the mapper finds out when they have the car on the rollers and varies from car to car dependent on the mods etc. The upper limit is usually set to the OEM VTEC crossover point.

You know what I don't know if it does happen with a standard car as the VTEC crossover point is usually a lot higher.
 
The standard car does it as well. You can get to almost 7000rpm on part throttle before the vtec changes over. As said it all works on the manifold absolute pressure or MAP sensor.
 
It's interesting what Loxy said about revving the car to 9k on the standard valve springs because the Spoon Sports ECU sets the limiter at 9100rpm which is crazy.
That's just a plug & play ECU and cannot be mapped but they fail to mention anything about the rev limiter being too high.

http://www.spoonsportseurope.net/in...-9100-rpm-lower-vtec-revised-mapping-ep3.html

Mine EP3 is booked in at TDI North on June 19th for K Pro so it will be interesting to see what the guys set my rev limiter at, I presume it will be 8600ish
 
9k is too high for standard valve springs never mind 9,100.

You'll also start having problems with the oil pump pickup on a K20A2 at 9k. Just google "K20 oil pump cavitation." ;)
 
just out of curiosity... what would happen if you set the VTEC really low, at say 2000rpm?? or would it literally be pointless?
 
bowman said:
just out of curiosity... what would happen if you set the VTEC really low, at say 2000rpm?? or would it literally be pointless?
Click to expand...

It would be pointless. The higher lift cam won't make as much power as the low cam as it is designed to be used higher up the rev range. You'd just lose power low down.

If you add forced induction however it's a different matter, but then you've changed the dynamics of the engine.
 
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