GTAm

[nicke]

Jim has to tell more about these pics, I just posted them.


Cheers, Nick

[nicke]

Jim has to tell more about these pics, I just posted them.


Cheers, Nick

[Jim K.]

Thanks Nicke, I couldn't figure out how to post pics myself.
I figured some guys would like to see clear shots of some GTAm stuff.
This is an engine I bought back in 1989 to rebuild and install in the Alfetta gtv I then had. I never got around to doing anything and in 1998 I sold it to a friend who thought he would put it in his 105 GT. Unfortunately, he got mixed up with some know-all AR ''race'' mechanics and the thing made...130hp (!!!) It then sat in his warehouse until 6 months ago, when he asked me to sell it for him. I had it around the house for a few months and I decided to buy new parts for it, which he would pay for out of the sale price. I didn't really want to put it together myself, as I'm involved with my own 6cyl stuff. Another reason was, that if I went ahead and assembled it properly, I think I would find it difficult to sell it-I would be inclined to keep it!! And I would too, but I have 2 75's now, no 105 and no gtv. So, a real decent guy building a GTAm replica came over from an English-speaking country and took the lot away. WAIT, there's more! This was the second of TWO the owner gave me! The other one I sold to a friend, also building a GTAm replica here in Athens. That one I'm helping assemble and when its finished, I'll send some pics again and hopefully some healthy dyno runs. That engine also has all-new parts. I feel strange letting go of them, but it wouldn't make much sense having two precious engines and no car-and no, I don't want another car! I'm more of a V6 guy now and I drool over a DTM 155 V6 motor-how times have changed! Ironic, if I had one of these, there's no way to use it as a daily driver (440hp/12500rpm)! Most of these jewels belong on a stand in the living-room I think!!
Any questions on the engine, fire away!
Jim K.

[PSk]

Okay I'll ask the first question

Not really a GTAm question but a question regarding the standard Alfa Romeo 105 series type cylinder head.

Can somebody please tell me why Alfa Romeo did not move the plug position wider (like they do for the twin plug) and then the single plug head could have had the same size valves as a twin plug?

Many engines nowadays do not have the plug in the centre ... so surely moving it 10mm sideways would not have upset the apple cart?

As for the GTAm engine ... I wish I had the funds ... and it is extremely interesting to see how flat the combustion chamber is and oh those oh so light pistons

Why also did they not change the production engine to this design MANY, MANY years ago. Surely would not have cost that much more to produce and they eventually (after wasting many years) went to a similar head.

Pete

[turbolarespider]

I think I can partially answer it...

The reason that they didn't move the single plug off to the side was that this is a fairly slow burn engine. With the chamber shape, either you would burn really slowly, or it may cause knock if cylinder pressures are too high.

And this didn't make production until the 70s due to cost.

The twin plug fixes the above across the board.

I'm actually surprised that the current Hemi motor is a TS head. VERY expensige for the extra machining, plugs, wires, etc. For a mass produced engine, not very cheap.

Eric

[PSk]

Quote:

Originally Posted by turbolarespider I think I can partially answer it... The reason that they didn't move the single plug off to the side was that this is a fairly slow burn engine. With the chamber shape, either you would burn really slowly, or it may cause knock if cylinder pressures are too high. And this didn't make production until the 70s due to cost. The twin plug fixes the above across the board. I'm actually surprised that the current Hemi motor is a TS head. VERY expensige for the extra machining, plugs, wires, etc. For a mass produced engine, not very cheap. Eric

[alfatwincam]

What I find puzzling about that GTAm engine for sale on ebay is that the 16v head has a 116 series number so it must be a 2000 GTAm 16v head and not the early 1900cc 67/69 head??? What you think guys?
The block has a 105 serial number gr5 so I would presume this is not a matching block/head as the serial numbers dont match up...

[Jim K.]

Its obvious the seller is not an AR buff. The numbers were taken out of the old CAS (Competition Adv. Service) or the old Perf.Options Catalog. I will repeat that 1900 16v and 2000 16v heads have different bore centers. To see the difference, just put two head gaskets on top of each other, lining up the stud holes: one 2000 gasket and one 1750/1800.

[Jim K.]

Ok, lets elaborate some more on the issue of the central plug-is it required? Are two plugs required? Or...three?
Unfortunately, the whole deal started out wrong, with the factory designing a crappy chamber with an outrageously large valve angle. With the piston at TDC, the actual 105 combustion space looks almost like half an orange peel and things get worse with high-dome pistons! Since (as correctly said) in this type of space flame travel is slow, its advantageous to locate ONE plug in the center, or TWO plugs on either side of larger valves (GTA). With one plug, you have large spark advance needs (up to 45* in some engines!) and with two plugs, much less advance is needed (about 34*). Lets clear out a basic misconception: Using two plugs is NOT a performance option but a CURE for the inability to properly burn the air/fuel mixture!
To substantiate all this and offer you some food for thought, I'll introduce those of you who don't mess much with the tech side of things, to the old Lotus Twin Cam 1,6 engine, introduced in 1963 (!!!). The valve angle is 54* (105's have 80*) The plug is offset to one side and there are excellent SQUISH areas on the sides ('what are those' asks AR!!), as the chamber is not completely round.This SHALLOW chamber (dictated by the valve angle) needs an almost FLAT piston! The advance required is rarely more than 34* (remember,only one plug!). These little 1558cc engines, can make up to...205hp on carbs! (Maybe you should have known this before you stuck to Alfas!). The little, light -and pretty- Lotus Elan Sprint, had 126hp std with this engine back in 1969-73 with two 40DCOE's. Imagine now this engine in 2liter size! 79hp/liter in 1970 with 8 valves?? It means 158hp for a 2000cc motor!
I consider the 80* valve angle, the greatest drawback in the 105's. If another angle had been chosen (the original was 90* in the older engine!) the GTAm would not have been so famous (engine wise only).
The shallower the chamber,the more difficult it is to place the plug centrally, but apparently, some enlightened engine designers don't give a damn!
To conclude, that remark about 3 spark plugs is not a joke! In 1969-70,some racing BMW 2002 engines HAD 3 plugs per cylinder, due to the weird configuration of the combustion chamber, with a giant piston dome totally screwing up the flame path!
Thats all for now, its been fun!

[turbolarespider]

To further enhance this discussion... more "why the Nord engine had to die..."

Combustion chambers that have huge surface areas are a major pain to keep the emissions down. The surface actually quenches the flame front before it actually reaches the wall, so the more the area, the more unburt hydrocarbons there will be.

Since Europe followed the US model in terms of emissions in the early '90's, the end of that motor was imminent. The cost of keeping the tailpipe emissions down to modern levels would have cost a ton. So it was far less expensive to take the Fiat block, and put a new head on it. The V6 is quite similar, but the 4V is not as bad. Even so, the family that started with the Alfa 6 will be done fairly soon.

When you look back on it, it's rather amazing that Alfa put so much technology into their engines to keep the power up and emissions down. SPICA is amazing, then they added a catalyst + air pump... Made similar power to a 5.0 Ford motor of the era. The Spider and GTV6 were some of the very early EFI cars out there, too.

Reading Jim's note above, it is kind of interesting to note that Alfa didn't copy what Lotus did.... But knowing some of solutions that they came up with for other items (sliding block vs panahrd or watts link for instance), it's not surprising that they didn't copy anyone, even if it was a better and/or more simple solution. Think about it- the 2.0 IS a derivative of the 1750, but it's not all that close, so very new head and block castings had to be made, which would have made it very easy to change valve angles and combustion chamber shapes. Alas, hindsight is almost always 20/20.

Sorry for taking this so far off topic...

Eric

[BigSwede]

He he he, take it easy Jim or they will hunt you down and burn you at the stake...

I'll let you hide out up here in Sweden if you need it, my minions will keep us out of harms way.

[Jim K.]

Thanks Mats, its allways nice to know there's a bunker for me to hide somewhere, hahah!
I can't help getting mad at this technology thing of our cars, when I see excellent solutions around we could have had too!
Why don't you look at all the 3 or 3,2liter motors in the market and check out torque figures and specific power output figures-then go get drunk!!

[PSk]

Quote:

Originally Posted by Jim K. ...old Lotus Twin Cam 1,6 engine, introduced in 1963 (!!!). The valve angle is 54* (105's have 80*) The plug is offset to one side and there are excellent SQUISH areas on the sides ('what are those' asks AR!!), as the chamber is not completely round.This SHALLOW chamber (dictated by the valve angle) needs an almost FLAT piston! The advance required is rarely more than 34* (remember,only one plug!). These little 1558cc engines, can make up to...205hp on carbs! (Maybe you should have known this before you stuck to Alfas!).

[Jim K.]

PSK, its not emissions that killed the Nord, but the factory mentality. Don't forget AR was a state owned company for umpteen years and this speaks volumes for the mentality,competitive spirit,initiative,incentives....and so on. A gov't or public service job, in most countries is like training for the afterlife. Why try, why think, a paycheck's a paycheck and its always there, whether you work or not. ''Why then compete with anyone else's products? We're selling ours, aren't we?''. I think its hard to argue with all this, don't you?
In page 13 of my book there's a picture of 3 heads AR experimented with, before finally choosing the 8v TS for...sentimental (marketing) reasons mainly. I call this decision great lack of foresight and a misinterpretation of market/competition research results.
We all know there are much better and faster cars around, yet we still love AR and our cars, this will not change, as its one of those things life can't explain-I like Wendy's,the next guy likes Big Macs, thats what it is. BUT, I still get pissed off thinking of a possible production 16v head, up on a par with the best of 'em!!
Jim K.

[turbolarespider]

Quote:

Originally Posted by Jim K. We all know there are much better and faster cars around, yet we still love AR and our cars, this will not change, as its one of those things life can't explain-I