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998 Vs 1275?


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#16 whistler

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Posted 20 November 2020 - 10:26 AM

998 or 1275 aren’t the only options, have you considered sourcing a 1098 crank, extra capacity = extra torque.
295 head, stage 1 kit, cam change could be a great engine

As well as the 1098 crank you'd need either 1098 pistons or the 998 pistons shortened on the crown, provided the crown is thick enough. If you over bore you can achieve around 1170cc and the long stroke will give very good torque.



#17 Minigman

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Posted 20 November 2020 - 10:26 AM

is your current 998 on a remote gearbox? What year is your mini?



#18 DomCr250

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Posted 20 November 2020 - 11:30 AM

I personally think you have made a good choice, whatever people say about the big bore engines I've personally found that the smaller capacity ones tend to last longer and are more reliable.  Back in the 80's we all had various large bore A series, what we found is that we quickly destroyed them (lack of mechanical sympathy), we all swapped to the smaller capacity in the end, not because they were cheaper but they put up the the abuse much better.

 

Good luck with the build, you'll be the only person with a smile on his face turning up at work each day after that 5 mile run!



#19 humph

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Posted 20 November 2020 - 11:36 AM

Sounds as though the builds mentioned are similar to the one Jim @ r.a.c.e engineering has just done for me;

998cc A+ block - Bored to 0.060" & skimmed to to get a C.R of 10.5:1
Crank - 998cc Re-ground
Head - 12G295 skimmed by 0.050"
Pistons - P-22463 +0.060" Flat Top
Cam - Minispares Evolution001
Timing chain - 3H2127EVO timing chain (simplex)
Final Drive - 3.44

Being as it's a road car I was advised against a lightened flywheel, but we'll see how it goes when he's up and running.

Frustrating thing is it'll be next summer (at the earliest) before I'll be able to try it.

**EDIT - Should add that the above will be mated to a HIF38 & MS stage 1 kit with K&N in a Vizard modded original airbox.

Edited by humph, 13 December 2020 - 12:08 PM.


#20 GT Jimmy

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Posted 20 November 2020 - 02:43 PM

Sounds as though the builds mentioned are similar to the one Jim @ r.a.c.e engineering has just done for me;
 
998cc A+ block - Bored to 0.060" & skimmed by ?? to suit head & pistons to get a C.R of ?? (I'll see if I can fill in these gaps)
Crank - 998cc Re-ground
Head - 12G295 skimmed by 0.050"
Pistons - P-22463 +0.060" Flat Top
Cam - Minispares Evolution001 
Timing chain - 3H2127EVO timing chain (simplex)
Final Drive - 3.44
 
Being as it's a road car I was advised against a lightened flywheel, but we'll see how it goes when he's up and running.
 
Frustrating thing is it'll be next summer (at the earliest) before I'll be able to try it.

Jim did my engine as well, it's the fastest mini I've owned

#21 Cooperman

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Posted 20 November 2020 - 03:42 PM

There’s no reason why a non cooper engine would be any less powerful than a cooper version. It was the 295 head, twin carbs, exhaust and cam that gave the cooper the extra power. The key to unlocking power from the 998 is the cylinder head, inlet and exhaust and upping your carb to a HS4 or HIF38. If your original engine is still good than I’d spend the money on a good ‘stage 3’ head, and a ‘stage 1’ kit. The cam could be changed but is a little more invasive. I had a 266 in a 998 and it was very good. The other thing to consider is the final drive. A 998 need to rev to get any good power out of it, so it needs a 3.44 or lower ratio (3.76) to liven them up. The 1275 on the other hand will pull a higher final drive 3.1 or even 2.95 and still accelerate ok.

My perfect 998 build would be as per my old one; 998 with overbore as required, twin HS2 with K&N filters in a metal original housing (to reduce induction noise), 266 cam, ‘stage3’ 295 head and lightened and balanced internals and a 3.76 final drive. It will go very nicely but will rev quite high on the faster roads and be noisy.



Well explained and very correct. The 266 is a great cam in a 998 with a well-floeing bigger valve head, but it does need to rev a bit to get the best results.

#22 John/Dominguez

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Posted 20 November 2020 - 09:05 PM

Well I guess that I can make my engine as good as a 998 cooper or even better but being on a “budget” I thought that that cooper engine could be quiet good as I would have 12g295 complete head the flat top pistons... and did the 998 cooper engine come with a better/stronger cam/crank? Just that alone would cost me even more than the whole engine, please correct me if I’m wrong!!

The mini is a 1974 clubman with rod change and so far I’ve bought a 7.5 inch disc brake conversions kit as well as the servo brake but I didn’t got around to install it thought as I haven’t got nowhere to plug it in in my existing inlet. I also got a full set of spax shock absorbers with Hi-los and new rubber cones all around.

Oh and by the way I can confirm that I’m the only person in my company that turns up to work every day with a big smile on my face ?!!

Edited by John/Dominguez, 20 November 2020 - 09:07 PM.


#23 John/Dominguez

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Posted 20 November 2020 - 09:12 PM

I drop a few picks of mi beloved clubman!

Attached Files


Edited by John/Dominguez, 20 November 2020 - 09:17 PM.


#24 Turbo Phil

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Posted 20 November 2020 - 09:14 PM

The 295 heads are good but be aware of the mileage it will have likely covered. If it’s like 99% of these heads usually are you’ll need to budget a decent amount to restore it.

This video covers pretty much all you need to know.

 

Phil.


Edited by Turbo Phil, 20 November 2020 - 09:18 PM.


#25 John/Dominguez

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Posted 20 November 2020 - 09:29 PM

Cheers Phil!! You got yourself a new subscriber!!

Edited by John/Dominguez, 20 November 2020 - 09:30 PM.


#26 Turbo Phil

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Posted 20 November 2020 - 09:38 PM

Cheers Phil!! You got yourself a new subscriber!!


Great, thank you.
There’s a couple of other videos on my channel to showing a 295 being restored and fitted with bigger valves. Enjoy!

Phil.

#27 John/Dominguez

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Posted 20 November 2020 - 10:14 PM

What do you guys think of 1275 head onto a 998 block?

#28 Avtovaz

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Posted 20 November 2020 - 10:46 PM

i am building a 998 with +20 pistons, using standard cam, standard head although i do plan to port it some and get the compression right up, then with the right tubular manifold etc, i think itll drive right. Now , the reason i say this is because im putting it on spi injection [ from a lada niva not mini] with speeduino ecu. My idea is that itll drive quite well as of the ignition mapping.

 

I do think part of the way a 998 is so revy is the dizzy? i maybe complexly wrong ;)



#29 Turbo Phil

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Posted 20 November 2020 - 10:49 PM

The 295 is a better option. The 1275 head will improve top end performance, but at the expense of bottom end/midrange. But on the other hand they can be picked up in good condition a lot cheaper than a good 295.

Phil.

#30 John/Dominguez

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Posted 21 November 2020 - 02:34 PM

Would it be a good buy that 998 cooper engine in your honest opinion? Even if is just for the parts thought




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