 |
924Board.org
Discussion Forum of 924.org
|
| View previous topic :: View next topic |
| Author |
Message |
Dutch924-racer
Joined: 23 Jul 2007
Posts: 1077
Location: The Netherlands
|
 Posted: Tue Feb 16, 2016 4:36 pm Post subject: S1 with S2 pistons different ignition timing ? |
 |
|
The S1 I have got has S2 pistons (8,5:1), the rest of the engine is S1
Do I need to set the ignition timing different for the higher compression ratio?
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
|
| Back to top |
|
 |
Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
|
| Posted: Wed Feb 17, 2016 1:21 am Post subject: |
|
|
Yes, set the ignition safe and keep fuelling on the richer side to avoid det without any thermal management. Also use as high an octane fuel as possible, if not with an octane booster if you are giving it full beans, especially in warmer days
A rolling road session will tell you have far to go before det. However I would do this in warmer (Summer) air temps than the current 0deg or so in Europe this week. The colder air intake will mask the det threshold until the Summer. Then in 30deg air temps you'll be knocking quite a lot.
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
| Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
|
| Posted: Wed Feb 17, 2016 1:22 am Post subject: |
|
|
also look at some protection with AFR and knock sensors
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
| Back to top |
|
|
Dutch924-racer
Joined: 23 Jul 2007
Posts: 1077
Location: The Netherlands
|
| Posted: Wed Feb 17, 2016 2:47 am Post subject: |
|
|
set the ignition ''safe'', is that more advance ?
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
|
| Back to top |
|
|
Cedric
Joined: 27 Aug 2004
Posts: 2608
Location: Sweden
|
| Posted: Wed Feb 17, 2016 4:22 am Post subject: |
|
|
Or have the boost adjustable, so you can find a safe level. A us wg spring would be nice+ boost controller. Of course you should always have a knock warning system.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/ |
|
| Back to top |
|
|
Kenodog
Joined: 25 Jun 2003
Posts: 2651
Location: Vancouver,B.C.
|
| Posted: Wed Feb 17, 2016 4:22 am Post subject: |
|
|
Retard timing. Less power, less risk of det.
Leigh
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140 |
|
| Back to top |
|
|
morghen
Joined: 21 Jan 2005
Posts: 8880
Location: Romania
|
|
| Back to top |
|
|
Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
|
| Posted: Wed Feb 17, 2016 5:42 am Post subject: |
|
|
| Cédric wrote: | | Or have the boost adjustable, so you can find a safe level. A us wg spring would be nice+ boost controller. Of course you should always have a knock warning system. |
I think this means potentially less boost, not more boost without IC  Just need to balance boost versus ignition. Lower boost, more ignition. Higher boost, less ignition. The dyno will tell which is best without loosing performance
I wouldn't boost above the stock 0.65-0.7 bar without IC in place.
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252 |
|
| Back to top |
|
|
ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
|
| Posted: Wed Feb 17, 2016 7:28 am Post subject: |
|
|
In my 941, I am running 8.7:1 CR, no thermal coatings on the slugs, 12 psi of boost (stock US-spec wastegate spring with manual in-cockpit boost controller). I have a Snow Performance Stage 2 Boost Cooler with MAP sensor that begins spraying at 5PSI and increases linearly to full spray at max boost (12psi). It runs on stock S1 US-spec ignition system (no initial advance or retard, standard 20° BTDC timing), and I always use 93 Octane premium fuel. No issues, no detonation. Has not been dyno tuned.
_________________
erstwhile owner of just about every 924 variant ever made |
|
| Back to top |
|
|
Cedric
Joined: 27 Aug 2004
Posts: 2608
Location: Sweden
|
| Posted: Thu Feb 18, 2016 4:33 pm Post subject: |
|
|
| Carrera RSR wrote: | | Cédric wrote: | | Or have the boost adjustable, so you can find a safe level. A us wg spring would be nice+ boost controller. Of course you should always have a knock warning system. |
I think this means potentially less boost, not more boost without IC Just need to balance boost versus ignition. Lower boost, more ignition. Higher boost, less ignition. The dyno will tell which is best without loosing performance
I wouldn't boost above the stock 0.65-0.7 bar without IC in place. |
¨
Yes exactly, a slightly lower boost level could be nicer to the engine than only retarding the ignition, which pushes EGTs upwards quite fast.
I have s1 WG spring (0,7bar), and the larger s1 kompressor (2664) on my s2 engine. It works for the track, ive driven it at track days above 30degC without any detonation. But there is very little margin for any raised boost. The car made 168hp on rototest hubdyno, according to rototest testing statistics a 10% loss is reasonable, which is 185hp at the crank. Sounds reasonable. But that is with the much more sophisticated s2 ignition system.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/ |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
924 FAQ (Technical)
