A peek into the block

[GT6Steve]

Here's a view of the block we don't see often.  I wanted to study the cooling area and to my disappointment it looks just as I imagined.  Only real shocker was how shallow the head stud pads are.  See second pic.  I milled .375 off the top of the block to expose these galleys.

[Deleted User]

I do hope you realise you have to use that all again  ;D

[GT6Steve]

That's the thinking....

[Deleted User]

post removed on request of author

[GT6Steve]

I was able to reach in and pick up pieces off the pan.  Is that air cooled enough?

[Jason]

Nice exposure there Steve :-) I just marvel at the engineering of casting these things in the first place!

[Deleted User]

As you see, and we found out a few yrs back, - there's solid iron between the pots.. :X
..doesn't do wonders for cooling that..... ;D :P

Now didn't you wonder why the darn things keeps overheating between the bores detonating like fury and burning out gaskets and pistons?  :o

And we KEEP hearing about Triumph engines doing 250bhp+ don't we......nothing quite like revealing the shortcomings of the b..ll sh...t brigade is there ?  :X  ;D

[GT6Steve]

So to think this through...The joints in question are the ones having about a quarter of their bores siamesed.  Limiting exposure to cooling water but adjacent to the intake valve.  The heat will develop closest to the combusted gases and gradient down the stroked area of the bore.  Hottest will be a certain distance away from the thermal mass of the head centrally between the siamesed cylinders.  upon compression the charge is heated by the hotspot of the cylinder and ignites at some value of compression.  Situation is worsened by higher RPM's and compression ratios.

The cooling effect of the head surface can't mitigate the hot spot but can improve it by moving the hotspot further down the bore perhaps beyond the volatile compression value.

Situation is exacerbated by poor fuel and inadequate cooling.

And not even GT ever built a 250 HP six cylinder engine?

Do I have the gist of it?

[lordleonusa]

So what exactly do you suppose might happen with an aluminium alloy head?  :o

Gareth, Dave P, Steve?

Hmmm

L

[GT6Steve]

If I've sussed it properly (or adequately) the hottest spot should move further down the bore and be cooler improving the situation.  We'll see what GT says in the morning.

[Deleted User]

GT6Steve wrote:

The joints in question are the ones having about a quarter of their bores siamesed.  Limiting exposure to cooling water but adjacent to the intake valve.  And not even GT ever built a 250 HP six cylinder engine?
Do I have the gist of it?

Actually the turbo engine knocked out around 200bhp at 3500rpm, and was so far off the scale after 4500 it became unmeasurable (reckoned about 350!)  ;D
That thing was wheel spinning a bit hard at 120mph and snaking down  the road....
so here's some ideas...

HEAT problems....?
There's several problems, almost all related to a temperature gradient up/down the block. Keeping this engine cool is why it's very difficult to get high powers reliably.  :-/

The head is always going to be the hottest bit on an engine (it's in the main upward convection current) and there's a little error above....cylinders with biggest problems are 2-3 and particularly 4-5,- no5 almost invariably melting and/or blowing thru the gasket into the water...because it's at the back so getting way too hot.

Adding to this, unlike the long Jaguar 6, there's no cool water feed to the centre of the block...this is essential to keep the rear cool on a pre x-flow engine design, and there's a chassis shielding it all from cooling air.

4 stroke engines are cooled by 3 things.
MOSTLY cool petrol, oil, and water.
Oil jets can absorb a good deal of rubbish from upper cylinder, and fuel injection increases the cooling to the head.

An alloy head is not going to make things any better at all, because the guys who try to make it simply have to understand the engineering and resolve the problems. ::)

I mean why copy something which doesn't work already, and keep all the defects?
The alloy head will just MELT gaskets into the soft alloy head and blow them even faster...
If it (LM25) hasn't been correctly heat treated, it will end up soft in no time and be unuseable even for a road engine within a week....(make a nice expensive door stop that!!)
When they designed the Longman mini 8 port alloy head, they OF COURSE made it to SOLVE all the mini engine defects in ONE hit,
Ie.- not leave some nasty 5 port pre crossflow thing and flog it in alloy just for fun.... ;D
Mini drivers are not noted for putting up with rubbish,- that's why they made something that worked so well, and they even changed the cam timing order and profiles from the 649 to the 60-80 super sprint beast ...specially for it PLEASE NOTE!  ;D

Cosworth turbo heads have PRECISELY the same problem after suffering detonation..and they're a good CROSSFLOW 4V design made by experts.  :'(

SO WHY?
The exhaust valves are together on 2+3 and 4+5 but those bores are not so heavily siamesed. However the bore no6 is right at the back and has a very narrow fire ring to number 5 which is running nice and hot.

Fire rings on the gasket are the things which get detonation going really well.
On the 2.3L/-250 this became really scary because the space between the bores was really really small, and if you heat the tops of the bores really strongly they distort.
However with some other things which helped cooling in that design, this could become less of a problem.

VIZ;-
Now, further element here, cam timing and stroke are also a big factor.
If your exhaust valve opens at say near 88-90 degrees, the engine is only operating with a stroke of about 38mm on a 2L (off cam this means an engine of about 1.0L). So the tops of the bores will only run hot for about 40mm and not get the big absorbtion and saturation we try to avoid.
Chamber and bore SIZE are also critical,- less iron to heat= less to cool

With a long stroke engine like a TR6 (which simply doesn't work with such a hot cam..opening at say 75-85 degrees) the effective stroke will be much longer say 60mm...so it will have an extra 20mm to heat the bores up, and this will be difficult to remove as it gets generated lower down the block.

Heat saturation is the thing.
ALL good race engines get COOLER as they get thrashed.
The ideal temp is about 70C.

On the Triumph 4 & 6 cylinder blocks the one that best avoids it, is the Spitfire Mk111, again for the reasons above,
....and again, because only 2 of the critical bores are siamesed, with only 2 of the roasting hot exhaust ports thermally stressing the head/block combination,- but these are slap bang in the middle where there's plenty of space... ;)

Also the Spitfire has an assymetric chamber design which the 6 cylinder doesn't have.
This actually helps quite a bit by pushing the centres of thermal stress away from each other. (that's in the next book)  ;D

There's a lot here, and it's pretty difficult to structure all of this into ONE compact post.  ::)
Sorry

[Deleted User]

GTEVO wrote:

An alloy head is not going to make things any better at all, because the guys who try to make it simply have to understand the engineering and resolve the problems. ::)

I mean why copy something which doesn't work already, and keep all the defects?
The alloy head will just MELT gaskets into the soft alloy head and blow them even faster...
If it (LM25) hasn't been correctly heat treated, it will end up soft in no time and be unuseable even for a road engine within a week....(make a nice expensive door stop that!!)
  ::)

Hmm heat treatment, I hadn't thought of that! Thanks for the heads up. Perhaps we should get an engineer in to help us, do you know any?

[Deleted User]

Joke?  :o
ALL alloy heads are heat treated

[Deleted User]

Joke!

[Deleted User]

edit these posts....but are you serious?
The heads in question have NOT been heat treated?

Or is this highly developed COV ironising and sarcasm?

[Deleted User]

If you want to produce a cross flow, or downdraft, or multi valve head then stump up, or shut up. We are constrained by market forces that dictate the use of existing manifolds, and believe me we did our market research, both trade, and retail. The added expense of producing the required ancillaries that would go with a radical redesign offer a tiny potential market. Also why bother, if you alter the head so radically then why not jiggle the block, fit a steel crank, or just fit a K series and be done with it. FYI however the head we are working towards does have some subtle modifications, all within something that is recognisably a Triumph casting.
There are plenty of engineers left in Coventry, you just have to know where to look.

[Deleted User]

GTEVO wrote:

edit these posts....but are you serious?
The heads in question have NOT been heat treated?

Or is this highly developed COV ironising and sarcasm?

I think we are at crossed purposes here, what heads are you thinking of?

[Deleted User]

What I have put my finger on is;-
It's not market research makes successful designs, it's proper engineering.

I can't think of a single successful design of alloy head that was ever made in Coventry.
Even the Jag ones were FULL of problems including major aggro with porosity.
Stuff made in Coventry simply has never been any good.

I can think of loads that were made in Milan or Northampton or various places in Japan that were brilliant, and even Mercedes ended up buying their stuff.

If you want to put an alloy head on a block that has major thermal runaway problems, and then assume it will be successful, then look at the stuff from the loonies in Brown's lane.
They had finally to go to Bridgend and FORD to make stuff which lasts, and even that blows up regularly.

Longman had a demand, he made good heads.

I simply don't believe an alloy head with some dummer consultant for "improvements" will be an improvement on a cast iron design with machined chambers and made by proper mass production tooling and methods.

I remain to be proved wrong.

I thought the whole idea of alloy was to make a "motorsport" head.
The original cast iron head is perfectly OK for the road, costs very little to maintain, is in plentiful supply and very reliable.
Alloy is FAR more fragile, especially for high compressions, not that much lighter and so far only successful on that overblown and stupidly priced lorry engine from Abingdon (The AH3000)

[Deleted User]

So it's a TLD thing is it? You boys should kiss and make up. He wasn't the only one we looked to for ideas. Unfortunately you weren't around when this project started so you didn't get asked. It's not to late for input, I'm off down the pattern shop this morning to check the latest modification. It's nice to see some positive encouragement for having a go at this, it makes it all worthwhile....

[Deleted User]

Hahahahahaha.... ;D
You looked to WHO for ideas  ;D  ;D
Neccessity is the father of invention  :o

No I think it's more a Coventry ......."we don't need people from Northampton to tell us how to make an engine thing"
They gave us the Dolomite & Jaguar 4V gems, all underpowered, unreliable, and worshipped in COV.  ;D

It's all about who you get into bed with (aiiieee  ;D )...and the future is NOT UK engineering based (because they produced so much bad stuff for years)....
Have you seen some of the latest things from San Yong and Hyundai, you don't see many in the UK yet!....

Shiver me timbers !!  ;D

[Deleted User]

Your heads are modified in Coventry are they not? We asked the guy you use for his ideas to.

[Deleted User]

His ideas were useful, and some were incorporated.

[Deleted User]

Well that's got me post rate up! I'm off into Coventry now to talk to some of those worthless, bag-o-shite engineers. I love this Forum, such diversity.

[Deleted User]

Interesting theory eh?
I have head work done by at least 4 different people, - most you don't know, including myself (when I have time).
Bear it in mind, we were talking about the BLOCK on this thread (maybe the thread in the block too!!  ;D ) and problems keeping it cool.  ::)

I mentioned some interesting ideas about cooling the block.
It would be EASY to incorporate those into the head, even on an old 2V thingy, especially if it's made of alloy.

Alterating the shape of the chamber and the config would also not involve MAJOR recasting problems, and TIG welding alloy is a "piece of cake" if you have time and patience aplenty.

Remember the idea of an alloy "motorsport" head is NOT weight.
Many commerical alloy heads are in fact massively heavy because of the demands for extra rigidity.
And also remember the Lotus TC was ALSO rubbish when it first went into production...
They had to incorporate strenthening ribs into it, - only the later BIG VALVE ones started to become the Lotus ELAN we all like to remember, despite the mess they made of the water pump pulley/belt design for most of its life......

It's all down to what you want.
A proper motorsport head that will work anywhere, or an unreliable lightweight "fad" that rebounds with warranty problems.  :-/

[Deleted User]

This is looking more and more like "Shrek"  ;D  ;D

(and C Dundee....you call this a head??? THIS is a head!)