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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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 Posted: Mon Aug 11, 2008 10:07 am Post subject: Rolling road Tuning |
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Hey guys,
I'm looking at getting my MS'd 924 on a rolling road, primarily to sort the spark map. Now I understand the theory, set it up running at a certain revs and then advance it until it pings then back off a bit, is there anything else to it?
Ta
Rich
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Tue Aug 12, 2008 1:33 am Post subject: Re: Rolling road Tuning |
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| Rich H wrote: | Hey guys,
I'm looking at getting my MS'd 924 on a rolling road, primarily to sort the spark map. Now I understand the theory, set it up running at a certain revs and then advance it until it pings then back off a bit, is there anything else to it?
Ta
Rich |
Oh yes.
Thats the old school method. With 2 valves per cylinder, heron head, dished pistons and offset plug, our old school motors follow that train of thought to some extent.
The modern scientific rule is to run the minimum advance that the engine needs to produce maximum torque. This keeps you as far away as possible from detonation while generating the most power.
Really this does require a dyno with a brake that will load your engine, so as to tune the high map bins. Thats the most important yet critical area. Believe what Poms call a rolling road is just that, a pair of rollers, Find one with a brake and a competent operator. And one with MS experience if theres any such thing. A GOOD tuner will know what to do.
Heres some light reading that explains the theory:
http://www.ls1tech.com/forums/archive/index.php/t-254868.html
http://www.efi101.com/forum/viewtopic.php?t=3184
http://www.efi101.com/forum/viewtopic.php?t=2523
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Tue Aug 12, 2008 2:04 am Post subject: |
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Will keep me amused for a few hours! Cheers RC!
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Tue Aug 12, 2008 2:04 am Post subject: |
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Will keep me amused for a few hours! Cheers RC!
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Tue Aug 12, 2008 2:15 am Post subject: |
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| Rich H wrote: | | Will keep me amused for a few hours! Cheers RC! |
So you`re at work eh?  |
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Raceboy
Joined: 01 Mar 2004
Posts: 2327
Location: Estonia, Europe
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| Posted: Tue Aug 12, 2008 3:53 pm Post subject: |
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On relatively low compression NA engines (less than 10:1) you can screw up the torque much before detonation occurs.
For every engine type, there's pretty spot-on basics that can be applied. I wouldn't even bother going to the dyno to tune 924 NA as you can tune it on the road to have 99,999% of the maximum torque in each load cell.
Dyno tuning is a must with highly built na engines that need to have camshafts adjusted etc.
On high-boost engines you also don't necessarily need to go dyno tuning because you almost never reach MBT before knock occurs. By high boost I mean 1,5+ bars.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold 
'84 924, turbocharged, sold.
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Tue Aug 12, 2008 5:26 pm Post subject: |
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OK, so is it a matter of best guess on the curve then?
How about this, get a willing volunteer (Or other wise, you can drive darling), drive on the motorway as steady speeds while I tune, advance the ign curve until it looses power then back off a bit.
Repeat at every load site I can get to.... ??
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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Raceboy
Joined: 01 Mar 2004
Posts: 2327
Location: Estonia, Europe
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| Posted: Wed Aug 13, 2008 5:52 pm Post subject: |
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You can't feel the power loss on the car unless it's 50 hp difference on 200 hp car or similar. It's a matter of common sense and experience and some reading.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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Rich H
Joined: 10 Jun 2007
Posts: 2665
Location: Preston, Lancs, UK
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| Posted: Wed Aug 13, 2008 6:23 pm Post subject: |
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OK, I'll see what I can do.
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec |
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