993 C4 remapping
06-28-2002, 07:44 PM
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993 C4 remapping
Hi All,
I had my 993 C4 remapped today at AmD, thought the results might be of interest. Before and after power and torque curves below, the runs were done in 5th gear, pressure was 1017mBar, ambient temperature between 24 and 29C. Engine is std but has RSR mufflers.
The "after" measured RWHP figure was 247.0 @ 6257rpm, which AmD's dyno reckons indicates 288.8 measured HP at the crank and 292.0 at the crank applying DIN 70020 correction. The equivalent corrected "before" peak was 280.0 @ 6448 rpm. The overall correction factor incl atmospheric correction was 1.182. Fuel was Shell Optimax (98 RON).
A 12HP gain seems good value for the £352 total cost, and as the torque plots show there are good gains throughout the range, up to 14 lb.ft in some areas. The small peak in the torque plots at 5300-5900rpm (both before and after remapping - wider after) is interesting as I have not seen this on other 993 plots or on the curve in the owner's handbook - perhaps that is thanks to Robin's RSR mufflers?
Subjectively the throttle response seems a lot sharper than I expected for the measured gains, maybe psychological
but very welcome nonetheless.
As an aside, although AmD's dyno is four-wheel drive the car was NOT measured that way, the drive to the front wheels was first disconnected - the instruction not to run a 993 C4 on a 4WD dyno came from Porsche in Germany, apparently, back when AmD were doing some dyno work for Porsche GB. It seems the diff can get damaged if the car is run on a 4WD dyno.
I had my 993 C4 remapped today at AmD, thought the results might be of interest. Before and after power and torque curves below, the runs were done in 5th gear, pressure was 1017mBar, ambient temperature between 24 and 29C. Engine is std but has RSR mufflers.
The "after" measured RWHP figure was 247.0 @ 6257rpm, which AmD's dyno reckons indicates 288.8 measured HP at the crank and 292.0 at the crank applying DIN 70020 correction. The equivalent corrected "before" peak was 280.0 @ 6448 rpm. The overall correction factor incl atmospheric correction was 1.182. Fuel was Shell Optimax (98 RON).
A 12HP gain seems good value for the £352 total cost, and as the torque plots show there are good gains throughout the range, up to 14 lb.ft in some areas. The small peak in the torque plots at 5300-5900rpm (both before and after remapping - wider after) is interesting as I have not seen this on other 993 plots or on the curve in the owner's handbook - perhaps that is thanks to Robin's RSR mufflers?
Subjectively the throttle response seems a lot sharper than I expected for the measured gains, maybe psychological
but very welcome nonetheless.As an aside, although AmD's dyno is four-wheel drive the car was NOT measured that way, the drive to the front wheels was first disconnected - the instruction not to run a 993 C4 on a 4WD dyno came from Porsche in Germany, apparently, back when AmD were doing some dyno work for Porsche GB. It seems the diff can get damaged if the car is run on a 4WD dyno.
06-29-2002, 07:32 AM
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John,
I'm guessing your car is a '96my or later with the Varioram motor right? Probably with the later '97my OBDII ECU if it was a simple re-program/EPROM swap.
I had my non-varioram "attended" to by AMD and have the same power and torque plots from the dyno. I had the AMD exhausts fitted as well.
My power curve looks identical to yours (peaking at 287HP @ 6139rpm) but the torque curve is completely differant. MUCH less flat!
Mine doesn't make more than 220lb/ft until 4000 revs and then rises steadily to a peak of 260lb/ft at 5585rpm. Yours has a considerably wider range of strong torque. Peak torque looks to be similar.
Having driven both types of motor this completely explains why the earlier car "feels" faster when the power hits, as the later one is actually accelerating faster before this point.
They are good guys at AMD, they know their stuff and do a good job.
I'm guessing your car is a '96my or later with the Varioram motor right? Probably with the later '97my OBDII ECU if it was a simple re-program/EPROM swap.
I had my non-varioram "attended" to by AMD and have the same power and torque plots from the dyno. I had the AMD exhausts fitted as well.
My power curve looks identical to yours (peaking at 287HP @ 6139rpm) but the torque curve is completely differant. MUCH less flat!
Mine doesn't make more than 220lb/ft until 4000 revs and then rises steadily to a peak of 260lb/ft at 5585rpm. Yours has a considerably wider range of strong torque. Peak torque looks to be similar.
Having driven both types of motor this completely explains why the earlier car "feels" faster when the power hits, as the later one is actually accelerating faster before this point.
They are good guys at AMD, they know their stuff and do a good job.
06-29-2002, 03:29 PM
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Tom: car is '96, Varioram - but I believe the European models do not have the reprogramming difficulty that afflicts US models from that year as the requirement for that problematic DME was only to meet US emissions regulations. AmD do reprogram the EPROM.
Mark: the extra torque lower down is also what I have heard as being the key difference between the varioram and non-varioram engines. As it hapens, Geoff at AmD has a varioram 993 engine in his 964 C4.
Having driven the car a little more since, I am particularly impressed by how much more responsive it feels at part throttle. AmD stress that they alter the whole map, not just the full load area, seems they do a good job of it too.
Mark: the extra torque lower down is also what I have heard as being the key difference between the varioram and non-varioram engines. As it hapens, Geoff at AmD has a varioram 993 engine in his 964 C4.
Having driven the car a little more since, I am particularly impressed by how much more responsive it feels at part throttle. AmD stress that they alter the whole map, not just the full load area, seems they do a good job of it too.
06-29-2002, 04:03 PM
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AMD sounds interesting...I've done a Google search and a search of the forum but can't find any contact details for them.
Could someone please let me know.
Thanks, James '97 993 C2S
Could someone please let me know.
Thanks, James '97 993 C2S
06-29-2002, 06:27 PM
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[quote]Originally posted by JohnM:
<strong>****snip****
As it hapens, Geoff at AmD has a varioram 993 engine in his 964 C4.
****snip****
</strong><hr></blockquote>
Hmmm .... very interesting. I'm sure there are others, but that makes at least three of us. I also know of another guy back east (US) that has a '98 engine in a '90 964. Not an easy conversion, despite what your intuition (3.6L in a 3.6L car) might tell you.
Do you happen to know if Geoff also installed a 993 6-speed?
<strong>****snip****
As it hapens, Geoff at AmD has a varioram 993 engine in his 964 C4.
****snip****
</strong><hr></blockquote>
Hmmm .... very interesting. I'm sure there are others, but that makes at least three of us. I also know of another guy back east (US) that has a '98 engine in a '90 964. Not an easy conversion, despite what your intuition (3.6L in a 3.6L car) might tell you.
Do you happen to know if Geoff also installed a 993 6-speed?
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06-29-2002, 06:44 PM
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Hi Randall,
Don't know if Geoff has changed the gearbox - but he does still have the original C4 4WD system, not sure if it would be possible to use a 993 gearbox with a 964 4WD setup.
Don't know if Geoff has changed the gearbox - but he does still have the original C4 4WD system, not sure if it would be possible to use a 993 gearbox with a 964 4WD setup.
06-29-2002, 07:26 PM
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Hi Mike,
Well, I'm guessing he still has the 5-speed, if he still has the 964's 4WD system. Like yourself, I don't believe the 993 C4 6-speed is compatible with the 964's 4WD.
Apparently, a 993 6-speed can be installed in a 964 C4, but you have to swap to the 993's front drive mechanism:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=4&t=001667" target="_blank">Thread that Discusses 964 C4 with 993 6-speed</a>
Well, I'm guessing he still has the 5-speed, if he still has the 964's 4WD system. Like yourself, I don't believe the 993 C4 6-speed is compatible with the 964's 4WD.
Apparently, a 993 6-speed can be installed in a 964 C4, but you have to swap to the 993's front drive mechanism:
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=4&t=001667" target="_blank">Thread that Discusses 964 C4 with 993 6-speed</a>
06-30-2002, 03:04 AM
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One more question please, John.
Does Geoff have a fixed spoiler on his 964? The VRAM engine sits very high in a 964 body. As a result, there isn't adequate headroom for the folded spoiler wall. My car now runs sans spoiler wall. An alternative to removing the spoiler wall is to install a fixed wing.
Does Geoff have a fixed spoiler on his 964? The VRAM engine sits very high in a 964 body. As a result, there isn't adequate headroom for the folded spoiler wall. My car now runs sans spoiler wall. An alternative to removing the spoiler wall is to install a fixed wing.
