54 replies to this topic

[HUBBA.HUBBA]

On the rolling road at vmax late last year and things went pop. Got car home and went in mood for 6 months. Then did a load of work on the car and changed the head gasket for a complete one! Wouldn't start, checked the compression and suprise, suprise cylinder number four was nearly nothing, poped a bit of oil down the bore and it got to 5 bar( others were 10 bar ish), so piston ring gone.
Question is, whilst changing the rings i may as well bore out, currenly 1293cc, what shall i go for without getting too hot?
Oh and out of interest, good old Smart Performance put new rings in less that 400 miles earlier ( no shock there!)
Cheers in advance

[Turbo Phil]

Have you actually stripped the engine ? You'll be lucky if just a ring is damaged, it will have most likely cracked the ring lands on the piston.

[Grahamxx]

We're running a 1380 engine supercharged with no heating issues....

[HUBBA.HUBBA]

Have you actually stripped the engine ? You'll be lucky if just a ring is damaged, it will have most likely cracked the ring lands on the piston.

Well I've only had the head off, the bores looked ok. But its more of a case of whilst I've got the engine out, put some decent pistons in, which begs the question what size bore to get max power with min heat issues.
FYI it's main purpose in life is to be a weekend, sprint/ hill climber , not for every day use. I'd like to get 130+ bhp. Got to 120bhp as a 1293cc with fueling issues.

[Wil_h]

I think the comment that Smart performance are responsible for a ring failure should be removed. You have no evidence of this. My guess is that you have detonation which has caused the head gasket failure and piston failure. As Phil says, more likey ring lands than rings. So the reality is that either your installation is flawed and either making too much heat or the CR is too high. Or possibly the RR guy ran it lean or with too much advance.

No. 4, failing would definately suggest to much heat and running into det. Your engine may benefit from dry decking and a bypass hose on the flywheel end of the engine.

In my experience of failed ring lands, little damage is done to the bore. A new set of pistons and a hone should be all that is needed. You could maybe consider a piston with a bigger dish.

[Sam Walters]

Have you actually stripped the engine ? You'll be lucky if just a ring is damaged, it will have most likely cracked the ring lands on the piston.

Well I've only had the head off, the bores looked ok. But its more of a case of whilst I've got the engine out, put some decent pistons in, which begs the question what size bore to get max power with min heat issues.
FYI it's main purpose in life is to be a weekend, sprint/ hill climber , not for every day use. I'd like to get 130+ bhp. Got to 120bhp as a 1293cc with fueling issues.

Change the orientation of your supercharger.

[HUBBA.HUBBA]

Have you actually stripped the engine ? You'll be lucky if just a ring is damaged, it will have most likely cracked the ring lands on the piston.

Well I've only had the head off, the bores looked ok. But its more of a case of whilst I've got the engine out, put some decent pistons in, which begs the question what size bore to get max power with min heat issues.
FYI it's main purpose in life is to be a weekend, sprint/ hill climber , not for every day use. I'd like to get 130+ bhp. Got to 120bhp as a 1293cc with fueling issues.

Change the orientation of your supercharger.

To What?

[HUBBA.HUBBA]

I think the comment that Smart performance are responsible for a ring failure should be removed. You have no evidence of this. My guess is that you have detonation which has caused the head gasket failure and piston failure. As Phil says, more likey ring lands than rings. So the reality is that either your installation is flawed and either making too much heat or the CR is too high. Or possibly the RR guy ran it lean or with too much advance.

No. 4, failing would definately suggest to much heat and running into det. Your engine may benefit from dry decking and a bypass hose on the flywheel end of the engine.

In my experience of failed ring lands, little damage is done to the bore. A new set of pistons and a hone should be all that is needed. You could maybe consider a piston with a bigger dish.

Cr is 8.3. Who said smart performance were to blame. Just stating the fact of who installed it and when. I'm entitled to a 'no shock there' considering the problems he caused me in the past. The RR guy - stuart at vmax ran it at about 27 degrees at 4500rpm and I think it was running rich at the time.
But anyway, back to the question, what cc gets best balance?

[Wil_h]

I think it is clear that you are infering that the cause of the failed rings is as a result of installation. Be honest with yourself.

27 degrees advance is quite a lot for a charged engine, I never run more than 25 on boost. What boost were you making at 4500rpm?

[matty...]

That does sound an aweful lot of advance!

I agree with Wil about the 'smart performance comment' I read it exactly the same way.

Whether or not you meant it, it sounds like you're suggesting they're at fault.

[new_zealand _minis]

get rid of the dizzy its just point less . ive got a few good 1293 supercharged megajolt maps round

[HUBBA.HUBBA]

get rid of the dizzy its just point less . ive got a few good 1293 supercharged megajolt maps round

I have considered a mega jolt, but it just seems like more work ( lot of scratching around for parts) and I just want to get my car on the road and drive it as soon as.

What tipped you over the edge and made you go for the mega jolt? I ask as I would need to get charger set properly first, before going down the mega jolt route otherwise I foresee lots of setting up problems over all not knowing if its the mega jolt or charger set up.

[HUBBA.HUBBA]

I think it is clear that you are infering that the cause of the failed rings is as a result of installation. Be honest with yourself.

27 degrees advance is quite a lot for a charged engine, I never run more than 25 on boost. What boost were you making at 4500rpm?

that's interesting, I was advised to go to 27. I'll keep it in mind when setting up again. cheers

[new_zealand _minis]

i was in the same boat as you . wanting a dizzy that worked . got a aldon one that was ment for supercharged motors . it was **** up top and would pink under load . even when retarded alot .

i did a hill climb . now with out a helmet on you can hear it pinking . with one one not so much . i just said screw it and gave it back ..


megajolt was easy .. cost me $50 ( 25 pound ) to get a trigger wheel put on my pulley , and a normal one at the same time .

few bits from trigger wheels .com . like the trigger wheel and some shield wire . and a unit its self

$30 coil pack ( 15 pound ) free crank sensor . make up some brackets for the pack and sensor . and som ht leads

got a map off another forum from a supercharged mini with the same spec as mine

and ran it . no more problems

also stopped the car stalling when you came to a stop sign . as you can play with the advance at idel .



just do it the megajolt ... bit of reasearch and you will have it done in no time

[HUBBA.HUBBA]

i was in the same boat as you . wanting a dizzy that worked . got a aldon one that was ment for supercharged motors . it was **** up top and would pink under load . even when retarded alot .

i did a hill climb . now with out a helmet on you can hear it pinking . with one one not so much . i just said screw it and gave it back ..


megajolt was easy .. cost me $50 ( 25 pound ) to get a trigger wheel put on my pulley , and a normal one at the same time .

few bits from trigger wheels .com . like the trigger wheel and some shield wire . and a unit its self

$30 coil pack ( 15 pound ) free crank sensor . make up some brackets for the pack and sensor . and som ht leads

got a map off another forum from a supercharged mini with the same spec as mine

and ran it . no more problems

also stopped the car stalling when you came to a stop sign . as you can play with the advance at idel .



just do it the megajolt ... bit of reasearch and you will have it done in no time

Hi there,

So the trigger wheel fits ok on the s/c pulley without fouling the rad? Excuse my ignorance, is the megajilt something you link up to a laptop to set up.
I've also had it on the RR at aldon and reckoned it was the cam, but i've only got a tame swiftune cam on it. I have a nagging feeling it might be the carb, so I got a spare to compare when up and running.