Any reason to think 9.8:1 pistons would cause grief

[gavinlit]

I'm currently researching the future engine rebuild and have been reading up a bunch of threads regarding twin plugging & compression ratios. The twin plug route seems to add a significant expense (anyone who's done this - I'd love to know what it came to in Aus) so I'm thinking of sticking with a set of 95mm 9.8:1 mahle pistons & avoiding twin plug issues. The magic number in the US seems to be 10:1 before twin plugging is a requirement. I'm wondering if 9.8:1 is ok on our 98 octane. If not, 9.3:1 will be used instead.

[Sumotang]

Sounds like you keeping the car?????

Why don't you just drop in a 3.6 while you at it?

[gavinlit]

.

[gavinlit]

Yep - keeping and driving until I feel it needs the rebuild. Taking a long term view, if I don't keep it I'll probably just be swapping cars over and over for the next few years as in the past. This car's been the first one that I can see myself owning for a longer stretch so I'm thinking it's worthwhile.

In the research phase at the moment. The 3.6 is an option but dosn't appeal. I've done engine transplants before & there always seem to be other side issues involved $$. I'd rather stick with a rebuild & if I can throw in a compression bump while I'm at it, well and good. Once the bump is too high then twin plugging seems to be required, at which point the 3.6 is probably a better option in terms of $. Either way I see the single plug rebuild as better value given that a 3.6 would have to be refreshed/rebuilt in any case. Never mind the fact that the 3.0 is plenty of power for my limited driving skills.

What's happening with yours? Driving til it goes?

[Sumotang]

Driving it till it exploads or I win Lotto. Any bets on what comes first?

When it gets rebuilt It will only be a stock rebuild except I want to put on some SSI's, new monty exhaust and put in 964 cams.

[obrut]

hey gavin

my targa car is 10.5:1. i ran it single plug on premium unleaded with zero detonation issues.

however, with twin plug it runs smoother and has better low end throttle response.

i think you'd be fine with 9.8:1

[gavinlit]

Damo - sounds a similar plan to mine. I'm also looking at improving the ignition a little if I can.
ok - thanks Ryan. I've still got that exhaust in mind. I don't know much about exhausts except I'd like dual in dual out. So the choice seems dual out at the sides or twin. I don't know if there's much difference between the two other than aesthetically. Any chance you could email or write on here any further info you've got on the twin out of yours (manufacturer, weight, dimension of pipes, twin vs dual etc).

[obrut]

manufacturer - monty i think, its all stainless steel
weight - absolutely bugger all, pick up with one hand
dimension of pipes - 2 in to suit SSI or early heat exchangers and 2 out with 2.5" centre outlets

here is a really really small pic...


sounds incredible

[Sumotang]

Ryan

To install that thing, would you remove the valance at the back of the car?

Would the car still be legal with the noise?

What are the size of the outlets?

[obrut]

hey damo

>To install that thing, would you remove the valance at the back of the car?

i haven't tried to fit it on a 74 and onwards car. it may just fit under the valance. if not, you could either recess the rear valance slightly around each outlet pipe or remove the centre part of the valance

> Would the car still be legal with the noise?

i think so, it is loud but not unbearable. like most sport mufflers, its not that loud at all below 4000rpm. i've currently got 2 'stinger' style mini mufflers on the my targa car (which have a perforated 2" pipe all the way through) and even they're not too bad below 4000rpm

> What are the size of the outlets?

from memory, they are each 2.5" in dia

it is for sale - but gavin has first dibs. let me know if you're interested and you can have a look if he decides to pass

[Sumotang]

Sounds pretty good. Make me No.2 on the list of potential buyers at this stage.

How much are you asking?

Is it at Nick's? If so, I will have a look at it next time I am over there.

Justing trying to figure out if it would look good on the SC.

[gavinlit]

I've sent you a pm ryan.
Damo - if they look ok & I get them fitted up before you do your top end we could go for a spin to see if you like the fit & note before you make a decision on yours.

[Howard R]

Its leaning against the side of the house in the driveway outside my shed. I will get Becko to drop it back to Nic. I keep forgetting.

[Sumotang]

Thanks

[obrut]

damo - muffler is sold.

[Sumotang]

No problem. I saw you on TV on the weekend in the 2005 Classic Adelaide driving off from the dam.

Did you see it.

[obrut]

yep, that's the best bit of footage we've ever got!