998 More Power
#1
Posted 04 October 2018 - 08:21 AM
#2
Posted 04 October 2018 - 08:48 AM
#3
Posted 04 October 2018 - 09:24 AM
Hi,
Due to the smaller bore of the 998 the valves on a 1275 head will hit the top of the block.
Cheers
#4
Posted 04 October 2018 - 11:32 AM
i got most torgue from a digital dizzy... ( i have to one from csi) makes the engine also run smother and better starting.
now i can climb a hill easy with 4.th gear... before digital dizzy only possible at 2. gear and a lot of rpm...
#5
Posted 04 October 2018 - 03:12 PM
#6
Posted 04 October 2018 - 03:15 PM
#7
Posted 04 October 2018 - 04:25 PM
Ideally you need a 12G295 head, suitably gas-flowed, but 295 castings are becoming hard to find these days.
Alternatively, ask 'TurboPhil' on here, to do you a nice gas-flowed head with slightly larger valves and a 10:1 CR. Then add a better inlet manifold and an improved carb. Fit a better cam, such as an Evo001 (great in a 998).
Lighten the flywheel and fit either a 3.44:1 or a 3.76:1 FDR.
Get the engine balanced and rev it right round to about 6000 rpm.
That's what can be done to a 998 if you so wish.
#8
Posted 04 October 2018 - 04:42 PM
#9
Posted 04 October 2018 - 06:30 PM
Everytime I drive my Dad's 998 (standard) I can't believe how much happier it is to rev compared to my SPI, I happily rev my SPI to 5000-5500rpm and whilst it is definitely faster in doing so I feel like the 998 is happier getting to these revs. I can't wait to build a 998 engine for my dad's car with a flowed head and a better cam, I think it will be fantasticIdeally you need a 12G295 head, suitably gas-flowed, but 295 castings are becoming hard to find these days.
Alternatively, ask 'TurboPhil' on here, to do you a nice gas-flowed head with slightly larger valves and a 10:1 CR. Then add a better inlet manifold and an improved carb. Fit a better cam, such as an Evo001 (great in a 998).
Lighten the flywheel and fit either a 3.44:1 or a 3.76:1 FDR.
Get the engine balanced and rev it right round to about 6000 rpm.
That's what can be done to a 998 if you so wish.
Edited by RooBoonix, 04 October 2018 - 06:30 PM.
#10
Posted 05 October 2018 - 08:39 AM
#11
Posted 05 October 2018 - 09:41 AM
Make sure you get the CR correct at around 10:1 after the head is gas-flowed.
For best power you don't want a water heated manifold. The inlet charge needs to be as cold as possible.
I built a 998 with a similar spec to yours but bored out to 1060 cc and it gave 65 bhp. Cam was a Cooper S 510.
A better distributor will help as well. Try an Aldon Yellow.
#12
Posted 05 October 2018 - 10:25 AM
#13
Posted 05 October 2018 - 10:26 AM
#14
Posted 05 October 2018 - 10:29 AM
Everytime I drive my Dad's 998 (standard) I can't believe how much happier it is to rev compared to my SPI, I happily rev my SPI to 5000-5500rpm and whilst it is definitely faster in doing so I feel like the 998 is happier getting to these revs. I can't wait to build a 998 engine for my dad's car with a flowed head and a better cam, I think it will be fantasticIdeally you need a 12G295 head, suitably gas-flowed, but 295 castings are becoming hard to find these days.
Alternatively, ask 'TurboPhil' on here, to do you a nice gas-flowed head with slightly larger valves and a 10:1 CR. Then add a better inlet manifold and an improved carb. Fit a better cam, such as an Evo001 (great in a 998).
Lighten the flywheel and fit either a 3.44:1 or a 3.76:1 FDR.
Get the engine balanced and rev it right round to about 6000 rpm.
That's what can be done to a 998 if you so wish.
Makes little sense though.
I never got why people think a 998 is capable of more revs.
Bore stroke ratio for a 1275 is better than that of a 998. (0.847 vs 0.868 for 1275 )A lighter flywheel would be better for your cause,cheaper and easier :)
#15
Posted 05 October 2018 - 10:33 AM
Twin 1.25 SUs with vizard work
12g202 head standard
64d dizzy with AC dodd work
Profiled needles by AC dodd
Maniflow exhaust system
Pancake filters
Dyno Reading was 65bhp and 63nm torque
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