The dry sump Gordini motor.

[schlitzaugen]

I see.

I thought you were boring the sleeves in that picture, but I understand now you were only turning the liner base.

 

[Frans]

Hi All,

The sleeves are now fitted, each in its own spot like a tailor-made suit. In the last 2 photos, you will see the torque plate that I loosely fitted without a gasket. I had that made to cover 2 pots at a time because I didn't have the money for the full size.

A used gasket gets fitted and then the torque plate gets torqued down by 80 Nm, that is what I use so that the sleeves distort into a certain shape. Then the sleeves are bored. When the head is fitted later on and torqued to the same specs, the sleeves distort into the correct shape.

I am told that this is so important that they do it even on Yankee cast V8 blocks. Apparently the cast iron on the V8s distort where the head bolts go in and they make a bulge. So with a torque plate that bulge gets cut away and forms a perfect circle.

Regards, Frans.

 

[geckoeng]

Hi FRANS,
What piston to sleeve clearance do you use for the race motor ???

I used to have a full plate for 16TS motors being taken to 78mm when I built for off road.

Ray

 

[schlitzaugen]

Hi All,
[...]

The sleeves are now fitted, each in its own spot like a tailor-made suit. In the last 2 photos, you will see the torque plate that I loosely fitted without a gasket. I had that made to cover 2 pots at a time because I didn't have the money for the full size. A used gasket gets fitted and then the torque plate gets torqued down by 80 Nm, that is what I use so that the sleeves distort into a certain shape. Then the sleeves are bored. When the head is fitted later on and torqued to the same specs, the sleeves distort into the correct shape.

I am told that this is so important that they do it even on Yankee cast V8 blocks. Apparently the cast iron on the V8s distort where the head bolts go in and they make a bulge. So with a torque plate that bulge gets cut away and forms a perfect circle.

Regards, Frans.

I would be very curious to put a DTI on that to measure the distortion. It is remarkable how much things move when they are bolted together even though 80Nm doesn't sound like much. I wonder if the liner seat were cut on the same machine just before the liners were put in if there was a problem anymore. Maybe one day I'll have a big enough surface plate to measure that.

 

[Frans]

Hi FRANS,
What piston to sleeve clearance do you use for the race motor ???

I used to have a full plate for 16TS motors being taken to 78mm when I built for off road.

Ray

Ray,

I'm no motormac so I don't know about those tolerances. It is something I leave to the Auto Engineers to do it right. Maybe if I had the machinery to do it, I would've known by now.

Sorry.

 

[schlitzaugen]

Ray,

I'm no motormac so I don't know about those tolerances. It is something I leave to the Auto Engineers to do it right. Maybe if I had the machinery to do it, I would've known by now.

Sorry.

I was thinking about that and my suggestion of cutting the seats and boring in one go, but you would need something only ze Germans thought of. It's a Wohlhaupter boring head. Wonderful thing, that. About 1200bucks (US) one. Don't think I've seen one in Oz. I would totally get one just for the engineering of it.

Oh, and a serious milling machine.

 

[Frans]

The block is back with the old newly bored sleeves. At first, I wanted to start putting the pistons in but then I thought about the ring gaps.
I spent most of this afternoon re-doing the ring gaps. The new engineering shop uses smaller clearances and I had to touch all of them a little with the grinder. They are now to size in their new bores and assembled.

PeterT, if you read this, I have increased the gap of the second ring as you suggested. Thanks. And now I know the reason as well after reading a bit on the Wiseco site.

Luckily I have my small lathe from Slotcar days and it makes the ring sizing so much easier and more accurate. Exact in fact because I can measure exactly the amount that I take off at every grind. And the edges are parallel as well.

Sizing the rings.

The gap.

The bottom end is now a bit further and I can soon start with fitting the dry sump.

I will update as I go along
Regards, Frans.

 

[JohnW]

So interesting Frans. Out of my league! Great work.

Why would you open up the gap for the second ring?

Our mine water conference in NZ was deferred to next year, about July. Fingers crossed!!! I doubt we'll go overseas again in our lifetimes at the present rate of progress, except NZ.

Best wishes

 

[PeterT]

Hi Hans. It's been a while since I looked at this thread and you've obviously been busy! I too have built more engines than I'd planned this year, after loosing mine on the dyno after two hours of running in Jan.

In regards to liners, yours are very similar to PSA XU5/XU9 liners. I'm so paranoid about keeping them round that I travel 3.5hrs to Baker Precision Engines, Molong. They made a fixture, that holds each liner individually and replicates the loads from torquing down the head. Wet liner engines are definitely not for the faint hearted!

@JohnW the 2nd ring always has a slighter larger gap to eliminate ring flutter. eg top 0.014", bottom 0.016".

I have a ring grinder but I like yours better.

 

[JohnW]

Hi Hans. It's been a while since I looked at this thread and you've obviously been busy! I too have built more engines than I'd planned this year, after loosing mine on the dyno after two hours of running in Jan.

In regards to liners, yours are very similar to PSA XU5/XU9 liners. I'm so paranoid about keeping them round that I travel 3.5hrs to Baker Precision Engines, Molong. They made a fixture, that holds each liner individually and replicates the loads from torquing down the head. Wet liner engines are definitely not for the faint hearted!

@JohnW the 2nd ring always has a slighter larger gap to eliminate ring flutter. eg top 0.014", bottom 0.016".

I have a ring grinder but I like yours better.

Thanks Peter. I learn a lot from your posts and appreciate it. And from Frans of course!

Regards

 

[Frans]

John,
According to Wiseco, the forged piston people, the bottom ring should be bigger so that when the gap closes up with expansion due to heat it should leave a definitive gap. Rings cannot close completely because the ends might but together and then there is no way for it to expand further and then it will break.

So, the small gap that still exists (and always will exist) on the top ring allows some compression to go through between the top and 2nd ring. If the 2nd ring's gap is also very small, or worse smaller, then the pressure of the gasses in between will lift the top ring off from its seat (bottom of the ring landing of the piston). That is then ring flutter because the ring "floats" in its groove.

If the gap is slightly bigger on the 2nd ring, then the gasses that would have been caught between the 2 rings can escape into the crank casing and your breather can do its job and get rid of it.

That is in detail and makes a lot of sense to me. I'm not sure if my explanation is good, but just say and I'll try another way again.

Regards, Frans.

 

[geckoeng]

This is true with even full cast iron blocks. "Grumpy" Bill Jenkins is a renowned drag car man and in the '70s was producing extreme horse power from stock block Chevys. For A and B class Stock drag cars. He would only use used blocks for the basis of his engines, and liked the ones removed from cars and left in piles in the scrap yards. Even with a full cast iron block he would re-bore and hone with a 1 inch deck plate. His engines were sort after by many top stock an modified drag racers, he even supplied top NASCAR teams with his engines. He used to explain the full details of blue printing a engine.

 

[schlitzaugen]

You don't need a DTI, just use a pair of inside calipers. You'd think that the pressure would be constant, and it is, as Pressure = Force/Area. However, the liner is not round and thus the pressure exerted changes around the perimeter of the liner. This is best explained via Young's Modulous, where E = stress/strain or E=FL/eA. The original length L, changes around the cross-section and thus e, the extended (or compressed) length varies, turning the circle into an oval.

Additionally, some materials differ in strengths in regards to compressive or tensile loads. eg steel exhibits the same strength in either direction, whereas concrete is extremely weak in tension. Cast iron is also very weak in tension. Thus expect different results from cast iron compared to steel. Regardless, the only sure way to bore/hone a liner, is to load it up as it would be in service.

I am weary of callipers and my suggestion to use a DTI is because I expect the distortion to be within the realm of hundredths of a mm not tenths. I have a proper bore gauge made by Mitutoyo but it is a faff to set it up such that you can traverse the length of a liner. With a DTI I can simply plunge with the mill quill (or you could do it with a pillar drill if you trust it enough). In the shop where Frans has his liners bored it would be a simple matter of chucking the DTI and plunging like I would. I would actually expect the workshop is using a DTI to make sure they line up the bores with the machine axis whether they measure the block seats or the liners themselves (I would actually measure the liner itself after clamping to make sure it is bored square with the crankshaft tunnel).

I agree with your explanation but I also think the loading induced by clamping is not even (for whatever reasons) and also the liner crystalline structure itself is not perfectly isotropic. Not to mention a simple non-uniformity in the liner seat can throw out the window everything even if it is only a speck (say .01mm). I see this in my setups on the mill where you can measure a million times and then you take your part to the surface plate and it shows immediately if there was a problem. A .01mm speck of crap stuck to your vice jaw can cause a variation from square/straight/flat/cylindrical of .1mm easily in a long/deep part. And things only get worse if the part is bigger. Not to mention .01mm is at the limit of what you can see. That is why I use the DTI a lot.

 

[pugwash]

off topic, but on topic, my father was posted in Darwin WW 2 looking after all kinds of requisitioned water craft ,keeping them running ,he used to tell of how they would turn up piston rings out of cast iron pipe ,they had to machine them a tad large,r to allow for them to spring into the bore once the gap was cut ,cant imagine how they didnt end up slightly out of round ,these are slow revving marine engines ,necessity being the mother of invention

 

[dauphproto]

Not forgetting that each piston manufacturer will have their own ideas about the amount of clearance required, dependant on the type of alloy they used. Some older forged pistons actually had a high rate of expansion, others do not, its worth remembering this when using old parts, as time goes on most mainstream stuff has better tolerances, one reason why efficiency has improved over the years. To be fair Renault were well ahead of the curve with this and their accuracy in the 60's was better than most others at the start of the 80's (except some Italian stuff)
Frans out of interest (and if it is not a state secret) What will the capacity of the Dry sump motor be?? I am guessing with Fiat pistons you are at the bore maximum giving about 1440cc on the short stroke crank.
My Dry sump Cleon unit is bored and stroked to the max 80.5 x 84mm giving nearly 1710cc, but as the block centres are 85mm there is nowhere else to go. It just needs to be Dynoed, but there is no point in doing this until the Dauph chassis is ready. It is getting there slowly. Lack of enthusiasm seems to be the main issue for me at Present.

 

[schlitzaugen]

Differences in crystalline structure (even though unlikely) would be impossible to measure with workshop equipment, as Young's Modulous for alloy steels covers a very narrow range, from approx. 202 to 218GPa. Thus the difference in "e" will be extremely small.

I didn't say you could measure it, what I suggest is that it does exist and it will cause different expansion rates at scales large enough that you can measure. Not that you can tell it's related to the crystalline structure.

In geology you often see this in minerals under the microscope. Distorted crystals, sometimes to the point of ductile shearing. Different reasons, but even a granite (which is considered very uniform and stable hence good to make surface plates out of it - not my opinion) has this kind of problem.

 

[Frans]

I eventually got the head back now that Covid allowed us more business! I had the valve seats and ports increased a bit for the new bigger valves with the guides re-lined. This head measures thick enough so I don't need to increase the combustion chambers and that is why I could afford to keep the edges flat for the benefit of a bit Squish area. It will surely help the combustion where the CR is now 11.85:1.

It is a bit down compared to the old head that was sitting at 12.7:1. Admittedly that is not where it started.

I am now at valve spring pressures and the photos tell the story. I had to turn some spacers for the inner springs so that the pressure is stepped up a bit. The next step is to cut and groove the new valves because they are Mazda and Nissan valves that are way too long for an overhead valve head. The cam followers are re-surfaced because I even have a new cut cam in it!

I've had so many delays with this dry-sump motor that it will be like a new era in my life when that fires up!!! It has become the proverbial "cops and virgins" story. You hear about them but never see them.

 

[JohnW]

I eventually got the head back now that Covid allowed us more business! I had the valve seats and ports increased a bit for the new bigger valves with the guides re-lined. This head measures thick enough so I don't need to increase the combustion chambers and that is why I could afford to keep the edges flat for the benefit of a bit Squish area. It will surely help the combustion where the CR is now 11.85:1.

View attachment 204230

It is a bit down compared to the old head that was sitting at 12.7:1. Admittedly that is not where it started.

I am now at valve spring pressures and the photos tell the story. I had to turn some spacers for the inner springs so that the pressure is stepped up a bit. The next step is to cut and groove the new valves because they are Mazda and Nissan valves that are way too long for an overhead valve head. The cam followers are re-surfaced because I even have a new cut cam in it!

View attachment 204231

View attachment 204232

View attachment 204233

View attachment 204234

I've had so many delays with this dry-sump motor that it will be like a new era in my life when that fires up!!! It has become the proverbial "cops and virgins" story. You hear about them but never see them.

You'll be running in the new camshaft and followers in the usual way Frans?

 

[manicgt]

I eventually got the head back now that Covid allowed us more business! I had the valve seats and ports increased a bit for the new bigger valves with the guides re-lined. This head measures thick enough so I don't need to increase the combustion chambers and that is why I could afford to keep the edges flat for the benefit of a bit Squish area. It will surely help the combustion where the CR is now 11.85:1.

View attachment 204230

It is a bit down compared to the old head that was sitting at 12.7:1. Admittedly that is not where it started.

I am now at valve spring pressures and the photos tell the story. I had to turn some spacers for the inner springs so that the pressure is stepped up a bit. The next step is to cut and groove the new valves because they are Mazda and Nissan valves that are way too long for an overhead valve head. The cam followers are re-surfaced because I even have a new cut cam in it!

View attachment 204231

View attachment 204232

View attachment 204233

View attachment 204234

I've had so many delays with this dry-sump motor that it will be like a new era in my life when that fires up!!! It has become the proverbial "cops and virgins" story. You hear about them but never see them.

Good to see things progressing and I am enjoying the write up ! Thanks for posting !

 

[PeterT]

Nice work Frans. Tell me about your valve spring tester. Did you make it?