mini power

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Discussion

phoneman

Original Poster:

6 posts

206 months

Thursday 22nd March 2007
quotequote all
Good morning all

Just built son new engine for his standard mini, needs some help please
seems main power band is around 4500 the seems to go down from there
Engine is a plus using 3.1 diff
plus fit pistons +40
Any ideas

Extra 300 Driver

5,281 posts

247 months

Thursday 22nd March 2007
quotequote all
What cam are you running, also type of rockers?

phoneman

Original Poster:

6 posts

206 months

Thursday 22nd March 2007
quotequote all
Cam is CAM4717 leyland and A plus rockers later type

fwdracer

3,564 posts

225 months

Thursday 22nd March 2007
quotequote all
If it is going flat past 4.5k rpm it could be a whole host of stuff ( because it isn't breathing properly or ignition/fuelling needs sorting out). It certainly isn't the FD as my tuned but ageing 1275cc motor will pull well over 5k in top on a 3.1 fd.

Anymore information? Does it have a modified head... what Carb are you running etc etc...

If you give people info to work with, you'll find plenty of help on this forum thumbup

phoneman

Original Poster:

6 posts

206 months

Thursday 22nd March 2007
quotequote all
Cheers

Its running on red jet su card inch 3/4 , standard head with 3angle seat valves
new plus 40 pistons flat top

fwdracer

3,564 posts

225 months

Friday 23rd March 2007
quotequote all
Spec sounds fine - the engine should produce decent torque (and therefore good acceleration). The head is probably the single limiting factor.

The valve sizes might be a bit on the small side with a standard head, but the 3 angle seats will help flow a bit. For a 1312cc motor on a 1.75inch SU it won't pull very hard over 5-5.5K without a head and/or cam change. I think the cam you are making reference to is a standard OEM profile.

Has it been set-up on the rollers? This could be the single best thing you spend your money on. Depending on where you are there are a couple of Mini (A-Series) specialists that could be recommended, that will help you extract the most out of what you have built.

phoneman

Original Poster:

6 posts

206 months

Friday 23rd March 2007
quotequote all
Cheers

Yes car has been set on roller but seem to run out of power at 4500 rpm (peak rev )

MR2Mike

20,143 posts

256 months

Saturday 24th March 2007
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Everyones assuming this is a large block engine but the OP hasn't actually stated this. The CAM4717 is the stock cam for the high compression 998 A+ engine, it was never used in the 1275 AFAIK?

If it is a 998 then the 1 3/4" SU is simply too large for it, fit an 1 1/2" SU on a decent small bore inlet manifold. First thing to fix on the A+ 998 is the cylinder head, they flow very poorly in standard form. Keep your eyes open for a good 12G295 head.

phoneman

Original Poster:

6 posts

206 months

Sunday 25th March 2007
quotequote all
Cheers for that
My error is using inch and half su.
using 4810 head with 3 angle seat