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Who can twin plug machine heads in Australia?


slowcar

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First question is why would you need to?

We have much better fuel in Australia, and better engine management options.  It's easy to get fixated on stuff the Americans do, but they are a long way behind us in terms of EFI and fuel quality.  You won't need to twin plug unless you're building something rather extreme, or you're planning on running on kerosene.

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Spencer Harrison 'RRR' would be another one to talk to.

BTW Stan Pobjoy up Coffs Harbour way can twin plug 356/912 engines. Complete cost including dizzy etc is approximately 2k. Though has been awhile nice ive spoken to Stan

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First question is why would you need to?

We have much better fuel in Australia, and better engine management options.  It's easy to get fixated on stuff the Americans do, but they are a long way behind us in terms of EFI and fuel quality.  You won't need to twin plug unless you're building something rather extreme, or you're planning on running on kerosene.

I think I'm with Syd on this, and maybe you dont need it with our 98 octane fuel, rather than the USA's lower octane.

Ive tried a few distributor and engine variations along the following lines.

The first had a 3.4 like the planned build, but on a 9.8 compression ratio, and on single plugs. That didn't need twin plugs, and went really well with the CIS it had.

I've had another 3.4 twin plug on MFI that gave us no end of trouble on the first 12 pin dissie it had, until we fitted a 12 pin JE Racing dissie out of the states which cured it. It was the the distributors fault. I think the compression on that one was 10.3? That went really well afterwards. David Young has that car in Tassie and its still going like hell in tarmac rallies. 

Then we had a 3.4 with 10.3 compression, built by my mechanic, which ran a single plug distributor, and it ran faultlessly on 46 PMO's. It wasnt short of horsepower or manners.

The current 3.4 has a 10.3 compression with a 964 twin dissie already in it. My mechanic is delighted. He believes that is the perfect solution. I've yet to tell him that we will be fitting a JE Racing dissie in due course because they look the business, and I cant stand the look of the 964 distributor.

In the end they all ran really well on BP 98 octane unleaded, and each either won championships or placed highly. 

Personally, I'd go for the twin plug because I love the look and the cache of it, but you could dodge it and go single plug if you use good fuel. 

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Yep the USA boys love the twin plugging. the ROW 3.2 motors run 10.3:1  so i was hoping not to have to go to the expense and effort of twin plugging? .People  in the us have said i will need to run 110 octane face fuel to get away with it.

im only going to 10.5 :1 that's only 2% higher than a STD ROW car.

What is the max advance i could run ? im running a MSD programmable ign system ?

Thanks for the feed back.

Does any one have a twin plug dissy for sale as a matter of interest? ( if i go that way)even a 964 ugly unit?

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I'm running a 3.2 with 10.3:1, single plug, on 98 only.

 

It has been advanced, but I'm not sure how much.

 

My mechanic can reprogram the original DME chip and got an extra 15 horses at the rear recently.

 

Before that, it's been running on 98 for about 4 years now.

 

So my experience with single plug has been no dramas.

 

I think Syd's build has special piston head work?

 

Cheers.

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Don't forget we measure octane slightly differently. Here's an interesting post:

http://www.e90post.com/forums/showthread.php?t=60433 

 

"As you most likely know Australia use the RON octane rating and you (USA) use AKI.

The conversion is: (RON + MON) / 2 = AKI

In Australia we have two high-end premium grades of fuel available:

 

  • 98 RON
  • 100 RON (includes 5% ethanol)

So, using Shell’s information, I have calculated the following ratings:

Shell V-Power 98: (98 RON + 85 MON) / 2 = 91.5 AKI
Shell V-Power Race 100: (100 RON + 89 MON) / 2 = 94.5 AKI"

 

  

This also means that if you use the same advance settings as the yanks, you're going to be in for a bad time.

 

 

FWIW if I go to the effort of using EFI (and I always do, as I don't like the finnickyness of carbies) I will never ever use a distributor system. Coil packs FTW. But then I've never been that hung up on looks. I'd rather something that works at optimum than is a PITA to live with but looks good.

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6922531829_6004b27e05_b.jpg

 

Here's a pretty fine twin plug set up.  This is my engine, as you can see the engineering was done by Autohaus Hamilton.  Just another option for you.

 

If you intend using high compression pistons with raised crowns, you may find that you don't get proper flame propagation as the advancing flame is shielded by the raised portion of the piston, hence the  thinking that twin spark is the go. 

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6922531829_6004b27e05_b.jpg

 

Here's a pretty fine twin plug set up.  This is my engine, as you can see the engineering was done by Autohaus Hamilton.  Just another option for you.

 

If you intend using high compression pistons with raised crowns, you may find that you don't get proper flame propagation as the advancing flame is shielded by the raised portion of the piston, hence the  thinking that twin spark is the go. 

i need you to stop posting that pic.

because i keep looking at it, then at my wallet, then back at the pic again.. :P

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Hi,  Im still undecided as to which way to go on this as, it is going to be very hard to tell if the motor is detonating due to open exhausts.

I could run Race fuel ?

what advance do you think is going to be safe @ 10.5 :1? single and twin plug?

lots of questions.

It is going to cost 3.5k plus to twin plug ?

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Slowcar

I really think you're worrying too much over whether you will get a good result with single plugs. You could avoid the expense of twin plugging, providing you use 98 octane fuel, and a good ignition system ie, MSD to make sure you have a good spark.

My 3.4 like this on PMO 46mm carbs still holds the SC lap record at Barbagallo, and ran without fault. It was a very happy engine road or track.

So far Sydr, Stardust and I at least have confirmed this setup works and I suspect that each of us has used our motors in fairly (ahem) extreme situations.

You can't run a twin plug engine in a CAMS production sports car class like SB or SC so there will be lots more around with single plug experience.

Any good 911 mechanic will confirm that you can do it, and perhaps most importantly, not suffer a penalty, if you use good ignition parts to get a strong spark.

Good luck deciding if you want to save the money or go with the 12 pin looks.

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Sorry Slowcar also meant to say that the last JE Racing 12 pin distributor cost me $2000 Aus and was sold to me by Dave at EB Racing. It was of excellent quality and he was really decent to deal with. Delivery was within a week.

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