RE: PH Origins: The 'Hemi' combustion chamber

RE: PH Origins: The 'Hemi' combustion chamber

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anonymous-user

53 months

Tuesday 23rd October 2018
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TooMany2cvs said:
NFC 85 Vette said:
What's the definition of big?

(6.85 litres - so it isn't massive in the grand scheme of things)
Riiiight.
Perhaps I should add some context, because you believe I haven't a clue what I'm talking about.

Cam in block V8's vary in size from the little Daimler at 2.5 litres, to mountain motors that currently top out at around 1001cid. Something that hovers around 400cid is fairly middle of the road. To be sympathetic to the rules of the class, we're limited to a 500cid max. I found that the fuel pump regulations are such that with a 21.0gpm limit, it's a struggle to fuel a 500 cube motor, but with a smaller displacement, it allows more flexibility with advancing the mag and spinning the blower quicker. As you know from the rule book we use, it's fairly limited and leans toward OEM archiecture, hence the 426 motor is the most common.

I tried a big block Chevy a few years ago (425.59cid in that example), it made a decent amount of power given that it had stock heads and a forged crank, but it wasn't happy running nitromethane (we went as high as 95% on occasion). The crank started to wander, the heads started to warp and the head studs were like knitting needles compared to the TFX / KB stuff. It was an interesting exercise but it was quite futile for going quickly (would have probably maxxed out at 6.30/230mph in that configuration) - I'd love to try it again, as few things sound as savage as a rat motor on fuel.

In any case, I suppose your point was that the American V8 way of doing things is crude, basic, and a bit crap. It's different strokes for different folks - in Europe the appetite has always been for small capacity engines, so anything larger than a 2.0L I4 or 3.0 I6 is seen as unnecessary. In the US, they always favoured simpler, bigger, less efficient means of making power.

'In the real world' - well, I'm building the Corvette in a small workshop in Northampton, that's fairly real world to me thumbup

'Lack of technological advancements' - the basic architecture works, and the materials and coatings have come a long way, making a 50 year old principle still a good option. There's no need to reinvent the wheel if what exists is fit for purpose.

TooMany2cvs

29,008 posts

125 months

Tuesday 23rd October 2018
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NFC 85 Vette said:
Perhaps I should add some context, because you believe I haven't a clue what I'm talking about.
Oh, I do. And it's totally irrelevant except in the world of Yank v8s.

NFC 85 Vette said:
Cam in block
Bingo. Single-cam pushrod. Woo-flippin-hoo. Ancient tech that everybody else dumped decades ago.

NFC 85 Vette said:
V8's vary in size from the little Daimler at 2.5 litres...
Bingo, again. 2.5 litres is a large engine, in the grand scheme of things. It's perfectly adequate to propel a large car at a very respectable rate of knots, unstressed.

anonymous-user

53 months

Tuesday 23rd October 2018
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Adrian, we could have politely discussed the differences between the US and European approach toward building performance engines. However, with you taking a diverge into personal digs about my level of knowledge on the topic of hemi engines, it's a bit of a waste of time, so I'll depart this thread - that way you can ridicule just the 426 Hemi and its derivatives, and not the people who use it to go racing.

I don't believe it's anything other than ignorance or a lack of understanding about how something from the 1960's can still be used so successfully today in certain types of motorsport. My angle on it (and the reason I posted) was from how the engine's been used since the early days of Top Fuel, as it's rarely spoken about in the mainstream i.e. on PH and other forums.

Probably for good reason it seems - turns out we're stupid for racing period correct cars because it's founded on old technology... (much like telling someone racing in classic F1 that their DFV isn't as good as an AMG turbo hybrid 1.6 V6). Of course the difference here is that F1 progressed into other tyes of engines that were better, or mandated for the application. The 426 Hemi was refined and improved, not replaced, because the bare bones of it were perfect for going fuel and alcohol racing back at the start. Hence why it's still used today, as crap as you think it is.

Different people have different preferences. I want to go quick in the 1/4 mile with a V8 that complies with the regulations - the 426 Hemi is the best engine for the job - makes good power, copes with high nitro % and it can be stripped down to the crank and rebuilt in less than an hour. That's quite critical when you need to put a fresh, cool rack in each run (as you know, top fuel engines experience quite high loads and temps).

Having the smallest displacement, most efficient engine you can find, is great for a road car (hence the popularity in Europe, as it always has been), but when you're trying to propel a recreation of a 1970's Funny Car down a track, the elephant motor was the weapon of choice back then, as it is now.

Cheers thumbup

TooMany2cvs

29,008 posts

125 months

Tuesday 23rd October 2018
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NFC 85 Vette said:
However, with you taking a diverge into personal digs about my level of knowledge on the topic of hemi engines
Except I haven't done that. It's quite obvious that you know a lot about that particular type of engine.

All I've done is point out the sheer irrelevance of mahoosive low-tech pushrod v8s to the greater picture of all types of car around the world. And you've taken that personally. I really don't much care about one very particular minority motorsport, and nor does 99.9% of the world.

BTW, you've done it again in the sentence I've just quoted... You've confused one specific family of Yank v8s with the generality - engines with hemispherical combustion chambers, not "Hemi" (r), (tm).

The sub-head of the article says it all... "The quest for more power led to the development of the hemispherical combustion chamber decades before Chrysler arrived" - the fact the author then went on to do a poor job of considering wider (and earlier) production examples is a different question entirely.

Lewis Kingston

240 posts

76 months

Tuesday 23rd October 2018
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TooMany2cvs said:
the fact the author then went on to do a poor job of considering wider (and earlier) production examples is a different question entirely.
Just for reference: they didn't fall within the remit of this article. As mentioned elsewhere, these articles focus on the earliest example of a concept or technology – I try to avoid them simply becoming lengthy, unrelenting lists of every company that has explored such avenues. In this case, though, Chrysler is so inexorably linked with the terminology that its use of the design is worth explaining for those not familiar with it. smile

As discussed at the end, several other manufacturers used the technology prior to Chrysler (and several did subsequently, such as Ford and Daimler) – as you quite rightly assert!

Edited by Lewis Kingston on Tuesday 23 October 16:12

irocfan

40,152 posts

189 months

Tuesday 23rd October 2018
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TooMany2cvs said:
irocfan said:
Who gives a st about hp/cc?
Here in the real world, anybody with a smidgin of basic common sense - not least because it's a fairly fundamental clue as to basic efficiency.

irocfan said:
The SBC is the world's most popular engine
Debatable, unless you struggle to comprehend that "the world" exists past the borders of the US. 'course, that also ignores the myriad of quite wide-ranging changes made to the small block family across 50 years of production.

Even if it is true, surely the fact that there were apparently no significant technical advances between the mid 50s and the early 00s is not particularly laudable?
Well plrase tell me why with the lardy SBC's that ive owned I'd have been appalled at to fuel consumption produced by scoobies/RS Focii etc - surely a crap old engine shouldnt be even in the same county, let alone neighbourhood fuel consumption wise?

I'll happily take a rebuikd cost of a SBC over that of a BMW 8... the Chevy 8 is also nearly the same size and weight as a 4-pot MX-5 lump. Hmmmm grand tech

TooMany2cvs

29,008 posts

125 months

Tuesday 23rd October 2018
quotequote all
Lewis Kingston said:
As discussed at the end, several other manufacturers used the technology prior to Chrysler (and several did subsequently, such as Ford and Daimler) – as you quite rightly assert!
Well, a passing couple of mentions of some very low-volume early weird stuff, with no mention of just how widespread it was in mainstream production...

Lewis Kingston

240 posts

76 months

Tuesday 23rd October 2018
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TooMany2cvs said:
Well, a passing couple of mentions of some very low-volume early weird stuff, with no mention of just how widespread it was in mainstream production...
I refer you to the first part of my previous post!
smile If it were focused on the history of production hemi-headed engines, and not the design itself, then there would be more on the latter (and that may be something for another day, such as one entirely on V8s). Ultimately I have to call an end to it somewhere – lest the article spool on indefinitely.

mrpenks

368 posts

154 months

Tuesday 23rd October 2018
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I like my CVH

anonymous-user

53 months

Tuesday 23rd October 2018
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TooMany2cvs said:
All I've done is point out the sheer irrelevance of mahoosive low-tech pushrod v8s to the greater picture of all types of car around the world.
You're talking utter and complete complete nonsense. And to call a modern pushrod V8 low-tech is plain ignorance.