Renault straight eight engine anyone..?

There was an entire paper some years ago on that engine in a Classic and Sports Car (?). Amazing how much effort was put in building the engine, mainly by hand, and when I say that I do not mean some dude installed the liners. I understand they cut the various openings for coolant, oil, other stuff by hand and filed it by hand. It looked like a primary school arts project in the end, but hey, it worked.
 
JohnW said:
Strange, isn't it? The extreme corrosion on older Renaults before decent additives were available (first here with the R4 I think) was often seen as extreme pitting (water pump spigots for example). I've read that small localised corrosion cells can form quite quickly, but you do need a conductive fluid. Using good coolant and changing by the instructions since we bought the R8 in 1973 has worked pretty well regarding corrosion. We never had a corrosion problem on a 16 with regular coolant changes. So I do suspect the fluid is the problem.

I've just seen extreme corrosion within three weeks on an aluminium fitting in contact with swimming pool water (slightly brackish and with free chlorine). Amazingly fast!!
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Cast iron doesn't corrode that bad, but Aluminium is another story. Iron is the most stable element in the universe whereas the amphoteric character of Aluminium shines when it comes to weird behaviour. One second you think you got it, next it's gone! Yeah, I am sure the fluid plays a big role, but I have seen Aluminium go weird even in absence of any liquids. My guess is the alloys are dodgy. If you look at the Japanese Aluminium blocks, they don't seem to have the corrosion problem on the same scale, and I am pretty sure people neglect Japanese cars all the same. I know I do.
 
Speaking of side valve engines.

Have any of you old codgers had any experience with deck relieving for improved gas flow? I have a side valve block which has a lot of pitting in the combustion area and I thought deck relieving would kill two birds with the one die-grinder. It's been a done thing by hot-rodders for decades and even the French have been doing it. Naturally this would be interfering with compression ratios so one would need to be careful. Any experience out there.. Jaahn perhaps?

www.jalopyjournal.com

Flathead Block Relieving for High Performance Flow - How To

Okay gang, many of you know that I'm a bit obsessed with flatheads (of all sorts) and racing. I sometimes take for granted all that I've learned and...
www.jalopyjournal.com www.jalopyjournal.com

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56 Fregate said:
Speaking of side valve engines.

Have any of you old codgers had any experience with deck relieving for improved gas flow? I have a side valve block which has a lot of pitting in the combustion area and I thought deck relieving would kill two birds with the one die-grinder. It's been a done thing by hot-rodders for decades and even the French have been doing it. Naturally this would be interfering with compression ratios so one would need to be careful. Any experience out there.. Jaahn perhaps?

www.jalopyjournal.com

Flathead Block Relieving for High Performance Flow - How To

Okay gang, many of you know that I'm a bit obsessed with flatheads (of all sorts) and racing. I sometimes take for granted all that I've learned and...
www.jalopyjournal.com www.jalopyjournal.com

View attachment 210457View attachment 210458View attachment 210459
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Radiusing the corner of the bore top adjacent to the valves seems to have been standard practice to improve performance of side valve engines in the past. A similar radiusing seems to help 'de-shroud' the valves of the overhead valve Ventoux engine. Obviously some restraint is needed to avoid exposure of the top ring land to the flame front, but even the most modest radiusing seems to help.
 
Hi Graham :rolleyes:
After forgetting that that engine was an 8 not a six I feel a bit embrassed :eek: but my excuse is yesterday was a bit stressfull ??

No I have not had real experience with decking old side valve motors. I have played with a couple of side valve B&S engines to give them a bit more grunt but not seriously. I think that radiusing the edge of the bore to help the flow into the cylinder would be the best thing to do and did that and took a bit off the head. Hard to say how much it improved it. Putting a bigger carby with a straighter manifold was also done. Good results though :giggle:
Ricardo did a design for a flat head to increase turbulence ; The Turbulent Cylinder Head was devised during the winter of 1918 - 1919. The patented low-cost combustion system increased the power of side-valve gasoline engines and went on to be incorporated into many vehicle makers’ designs in the 1920s and 1930s. Modern up to date ideas here ??? :confused:
So I might think that you should be careful not to interfere with any squish built into the design. I also read that you could use fast lift cams that just open quickly and dwell open for a while as there is no chance of hitting the piston or each other.
Jaahn

ps://en.wikipedia.org/wiki/Harry_Ricardo
https://en.wikipedia.org/wiki/Flathead_engine
PS Harrisonati has put that interesting link in while i was writing. Looks good ! No time to read it in the short time for editing !!
 
Thanks Phil, Yes one needs to be careful to not take too much off near the bore itself to stop the rings getting hooked up. I'd imagine that a good skim off the head and/or a thinner head gasket would be in order as well to help increase the compression ratio.?
 
Andrew Watkins said:
Bugatti was quirky

Instructions for valve grind in some of his cars started with “remove rear axle”

OK if one has a team of slaves to maintain it I suppose

But still some of the most beautiful and effective cars ever made

Andrew
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Correct as I understand it. Non-detachable cylinder head.......
 
Thanks Yaahn, My main intention is to clean the ports and do a semi polish and to remove the pitting from the deck surface. So while I'm at it It makes sense to smooth things out as shown in the link above. Leaving the pits in the combustion area would have the opposite effect and therefor impede gas flow.
 
jaahn said:
Hi Graham :rolleyes:
After forgetting that that engine was an 8 not a six I feel a bit embrassed :eek: but my excuse is yesterday was a bit stressfull ??

No I have not had real experience with decking old side valve motors. I have played with a couple of side valve B&S engines to give them a bit more grunt but not seriously. I think that radiusing the edge of the bore to help the flow into the cylinder would be the best thing to do and did that and took a bit off the head. Hard to say how much it improved it. Putting a bigger carby with a straighter manifold was also done. Good results though :giggle:
Ricardo did a design for a flat head to increase turbulence ; The Turbulent Cylinder Head was devised during the winter of 1918 - 1919. The patented low-cost combustion system increased the power of side-valve gasoline engines and went on to be incorporated into many vehicle makers’ designs in the 1920s and 1930s. Modern up to date ideas here ??? :confused:
So I might think that you should be careful not to interfere with any squish built into the design. I also read that you could use fast lift cams that just open quickly and dwell open for a while as there is no chance of hitting the piston or each other.
Jaahn

ps://en.wikipedia.org/wiki/Harry_Ricardo
https://en.wikipedia.org/wiki/Flathead_engine
PS Harrisonati has put that interesting link in while i was writing. Looks good ! No time to read it in the short time for editing !!
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Very clever man, Mr Ricardo!
 
56 Fregate said:
Thanks Phil, Yes one needs to be careful to not take too much off near the bore itself to stop the rings getting hooked up. I'd imagine that a good skim off the head and/or a thinner head gasket would be in order as well to help increase the compression ratio.?
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When trying to increase compression ratio by reducing combustion chamber volume, the are three main methods - shave the head, 'deck' the block or use domed pistons. If we don't want to use special pistons, then there are prudent limits to what should be removed from either surface. A modest head shave combined with modest 'decking' of the block is probably the best and safest way to go!
 
harrisonati said:
When trying to increase compression ratio by reducing combustion chamber volume, the are three main methods - shave the head, 'deck' the block or use domed pistons. If we don't want to use special pistons, then there are prudent limits to what should be removed from either surface. A modest head shave combined with modest 'decking' of the block is probably the best and safest way to go!
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What I should have stressed is that radiusing has advantages over simple machined relief: Firstly, it doesn't increase combustion chamber volume as much. Secondly, gas flow is better because of the radiused edges. Also, as to methods of increasing compression, I'm always very cautious of thinner gaskets.
 
Yes you might be right about using a thinner gasket on a long head. Yes I know about the advantages over a radius V sharp machined corners, it's a universal truth over all material types.
 
harrisonati said:
What I should have stressed is that radiusing has advantages over simple machined relief: Firstly, it doesn't increase combustion chamber volume as much. Secondly, gas flow is better because of the radiused edges. Also, as to methods of increasing compression, I'm always very cautious of thinner gaskets.
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Yes, gaskets do have design parameters to meet, and changing squish with temperature isn't trivial I imagine!
56 Fregate said:
Yes I've been reading up on Mr Ricardo.
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Find "Engines and Enterprise" by John Reynolds if you can, the enlarged second edition. I guess the engineering firm is still going too -
. We owe him a huge dept, including the cylinder head design that made high speed diesel engines for cars possible at all.
 
Wow. I wonder what the opposite side (to the valve) of the piston/bore looks like in those engines after a while.

Are those pushrods for 2 OH exhaust valves I see?
 
56 Fregate said:
Yes, quite a bit it seems and I note they made the pistons to suit.
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Yes, the head is dead flat with quite large inlet valves. The plug is centrally located so it is effectively an upside down hemi. The reason Jack Swaine designed it this way is an interesting read.
 
schlitzaugen said:
Wow. I wonder what the opposite side (to the valve) of the piston/bore looks like in those engines after a while.
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That's my Rover 90 engine in the photo. I had the head off due to a burnt exhaust valve on No 1.
It was 60 years old at the time, was still standard bore size and there was no discernable bore wear evident.
 
The little bit I know about side valve engines is in regards to BMW R71 motorcycles. There is a point of diminishing returns when compression ratio is being chased as this then takes away the ability for the incoming charge to enter the chamber. I think about 9 to 1 is as high as can be generally achieved, and although these engines are only 5.8? to 1 standard, the claim is production of 22Hp. The head has a raised semi circular section opposite the valves that goes partially down the bore to increase squish/compression I expect.

I have a half sorted/ machined etc a motor, and will eventually assemble a warm version of this engine with approximately 8.5 to 1, larger valves with thinner stems to reduce weight, some porting, and a upgraded cam. At 750cc it might even make 30Hp. A retirement job maybe.
 
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