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998 More Power


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#1 germini30

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Posted 04 October 2018 - 08:21 AM

I have swapped my mg metro engine back to my original 998. I am happy with the 998 but some extra power would be nice. I have got a 12G940b head here, which is the spi head. I was thinking of fitting this to the 998 along with a nice cam. Seeing as I have the head all I would need to spend is on a camshaft, gaskets plus any work needed to fit the head. Also what carb would I need, I have a spare hif44 here to.

#2 cal844

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Posted 04 October 2018 - 08:48 AM

If it's an spi head the block needs pocketed

#3 Bat

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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  :proud:



#4 ings

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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 cal844

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Posted 04 October 2018 - 03:12 PM

On my 998 I have installed a stage one kit and a 65D dizzy from a metro, it pulls well but looses speed on steep hills due to lack of oomph

#6 germini30

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Posted 04 October 2018 - 03:15 PM

I have a stage one kit fitted. By the looks of things after that it starts getting expensive. I fancied a 998 but with a nice head and cam

#7 Cooperman

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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 germini30

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Posted 04 October 2018 - 04:42 PM

Just gone from a 3.4 to a 3.1. Much better for me

#9 RooBoonix

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Posted 04 October 2018 - 06:30 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.

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 fantastic

Edited by RooBoonix, 04 October 2018 - 06:30 PM.


#10 germini30

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Posted 05 October 2018 - 08:39 AM

Cooperman what about a 12g202 head, are they any good. I would rather bolt on stuff than getting the block pocketed etc. A nice head along with the evo cam I am thinking of getting. Already have a stage one kit with k & n panel in a modified airbox, heated inlet, maniflow free flow inlet and maniflow exhaust system. With an evo cam and head I think that the engine would be plenty for me

#11 Cooperman

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Posted 05 October 2018 - 09:41 AM

12G202 is a good head.
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 germini30

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Posted 05 October 2018 - 10:25 AM

I have megajolt already. Its a wasted spark so fires twice on each cycle

#13 germini30

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Posted 05 October 2018 - 10:26 AM

Is the 12g202 alot better than the cam4810 that is fitted currently

#14 Dusky

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Posted 05 October 2018 - 10:29 AM

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.

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 fantastic

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 petey81

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Posted 05 October 2018 - 10:33 AM

My spec is 998 with 20thou overbore.
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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