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How long is the fuse on the A+ grenade?
https://www.ausmini.com/forums/viewtopic.php?f=2&t=14692		 Page 1 of 1
Author:  Mokesta [ Sat Jan 07, 2006 10:32 pm ]
Post subject:  How long is the fuse on the A+ grenade?
OK a mate of mine regulary runs track days at Willowbank, AKA Qld Raceway. I want to take Mokesta out and do some laps on the next on (16/2/06) but I'm not sure how robust the engine is. I can't afford a new engine & gear box but really want to play. :? QR is a horsepower circuit but the sprint circuit isn't too bad or boring for minis. Still a large part of the lap is full throttle.

Mokesta has an MG metro 1275 donk on original crank, pistons rods etc but with the following mods:
BLOCK: Double row timing chain no tensioner, central oil pick up, new oil pump 300km ago, new water pump, 87 degree thermostat, oil cooler, new big-ends and main bearings. 75psi oil pressure cold, 60 idling hot.

HEAD: Double valve springs, 1.5 roller tipped rockers, mild head porting by Liddells in Brisbane, unleaded valve seats, bronze guides, Rimflo valves, standard size for MG metro

INDUCTION: A bit of Visard on the HIF6, pod style K&N filter on ram tube of sorts. 1.75 LCB, RC40 rear box, straight through hot dog centre.

GEARBOX: Stock standard A+ gearbox with new bearings 5,000km ago and new single diff pin 300km ago. 3.7:1 diff.

I don't know the km the engine has done but it has only been 7,000 km in the 10 years I've had it and the compression was great when I got it from Northern Mini Spares.

So my questions for people with experience in these this are:
1) What is a conservative rev limit I should use? :?:
2) How many minutes/hours/km of track use can an engine stand before it does bearings, rings, throws a leg out of bed? That is, what sort of rebuild frequency do owners who regulary race their minis get? :?:
3) Is there a weak spot in my set-up that I should fix before venturing out onto the track? :?:
4) Anyone else interested in a QR track day? If yes see posts by "mountain runner" on www.boostcruising.com or PM me for details. :wink:

PS I'm not concerned about the suspension, brakes or tyres, they're sorted! 8)

Please don't hijack this legit Q. If you don't know, have never run a mini on the track or a just a "rerits tihs" like some regulars please dont bother.

M
Author:  simon k [ Sat Jan 07, 2006 10:49 pm ]
Post subject: 
track days usually only give you a session of a maximum of 10 laps or so, so you're not out for long, limit yourself at whatever revs you use on the road - 6000 ish

go out and have fun, don't try to beat anybody but yourself and just be sensible - I've done a few track days in my road car and never had a problem (that wasn't fixable in a couple of hours - broke a disk rotor at wakefield)

if something starts to make a wierd noise, don't say 'oh, it'll be OK', go back to the pits and check it out - first time I went on a track in my S, the first run took the fluff off my clutch and by the end of the run I had no clutch at all - back in the pits I adjusted it properly, before the second run I got a big surge of oil through somewhere and blew smoke for the first couple of corners, and after that everything was peachy - I reckon it did the motor good

just make sure everything is done up properly - be a strict scrutineer for yourself
Author:  drmini in aust [ Sun Jan 08, 2006 7:16 am ]
Post subject: 
An A+ should be good for a max 6500 rev limit, but if your cam is stock? there's no power over 6500 anyway.

My 1310 regularly turned 8K at Wakefield Pk track days- these days I try and keep below 7500 (with S crank).

As Simon said you are not out there long enough to really kill anything, just keep an eye on oil pressure and water temp.. bring it in at any sign of trouble.

Have fun!! :P
Author:  justminis [ Sun Jan 08, 2006 8:11 am ]
Post subject: 
Hi Mark, as said 6500 shopuld be your rev limit. I have run my sprint mini at QR a few times now and the biggest issue is oil surge on turns 1, 2 & 6 (last one coming on to straight). You have centre oil pick up so should be right but make sure you keep the oil level full or a little over.
No obvious weak spots in your motor but IF you were going to do this on a regular basis I would think about better (& new) rod bolts.
Have fun.
Steve
Author:  Mokesta [ Sun Jan 08, 2006 9:52 am ]
Post subject: 
Thanks guys,

So 6,500 rpm is max for stock bottom end? Good, I've never revved it harder than 6,300 and usually keep to less than 6,000.

Oil surge and worn oil pump are the reason for the new main and big end bearings. Plus I was running Magnatec oil and now run Penrite HPR50 which is thicker. The bearings didn't go completely but hot oil pressure was low at idle.

I reckon I'll sign up. Anyone else interested? Its a week day due to rude weekend track access proces but there is 1/100th of a second accurate lap timing and a large group of sensible enthusiasts. D1cks don't get invited back.

M
Author:  cush [ Sun Jan 08, 2006 11:21 am ]
Post subject: 
drmini in aust wrote:
bring it in at any sign of trouble.

you listening, hugh?


:)
Author:  drmini in aust [ Sun Jan 08, 2006 12:23 pm ]
Post subject: 
Mokesta wrote:
Thanks guys,

So 6,500 rpm is max for stock bottom end? Good, I've never revved it harder than 6,300 and usually keep to less than 6,000.

Oil surge and worn oil pump are the reason for the new main and big end bearings. Plus I was running Magnatec oil and now run Penrite HPR50 which is thicker. The bearings didn't go completely but hot oil pressure was low at idle.

I reckon I'll sign up. Anyone else interested? Its a week day due to rude weekend track access proces but there is 1/100th of a second accurate lap timing and a large group of sensible enthusiasts. D1cks don't get invited back.

M

I found HPR50 (40W/70) is TOO thick- in cool weather it grabs the primary gear to the crank... can't get gears. :cry:
But HPR40 (25W/70) is OK. :)
Author:  WhoDat [ Sun Jan 08, 2006 12:29 pm ]
Post subject: 
Yeah - I'm listening Cush :lol:

OK Mokesta - As Cush is hinting - I've just done this exercise the wrong way - Here's my story - pretty well the same power plant that you have, same size, same mods, same power, same stats - yours sounds like it may have a little more but near enough. Mine was a fresh bare block and Trans rebuild, 1000k of running in and then hit the track. Result - BANG - well it was a "clank, clunk, rattle & tinkle" acutually but you get the picture. NIKE is sometimes not the best approach.

Some good advice is here already but the bits that I relate to closely now - are

    be a strict scrutineer for yourself
    if something starts to make a wierd noise, don't say 'oh, it'll be OK', go back to the pits
    keep an eye on oil pressure and water temp.. bring it in at any sign of trouble.

The only thing I would add would be to start slow and build throughout the day. I think the 6.5k suggested limit may be a bit high for first time out but call it a max for the day and build up to it over the sessions.

Best of luck and You'll have a ball if you ease into it :wink:
Author:  Mokesta [ Mon Jan 09, 2006 8:29 am ]
Post subject: 
Thanks Dr. If only I could remember not to trust my memory!! I use HPR 30 whigh I always think is 50 because it is a 30W-50 I think..

The QR February track day is now on Feb 21.
M
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