4XF1-WT project

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Re: 4XF1-WT project

Postby dapinky » Sat 26.03.2016, 12:06

Chris,

that is very helpful, thank you.

I haven't had any 'new' machining done yet - I'm still in the 'collecting parts' stage of the work.

I hadn't considered decking the block until you mentioned it - I suppose that I won't know if it is needed until I seperate the bits. As I say, I know the head could do with a bit of flattening, and as the block will need to be bored out by 1mm per cylinder (probably slightly less due to the current wear!), I don't know if the machining of that bit will cause any sort of lip at the top of the block.

My knowledge of these things is a bit limited, but part of me says that cast iron shouldn't have deformed over the years, so let it go - but part of me says that whilst it's being done, get it decked.

The changes in compression ratio *may* have some effect on the final decision with going wider on the bores, but on a turbo car the lower numbers are better (within reason).

I think that the final decision will be left to the rebuilder, but I want to be able to give him as many options as possible, and not just throw him a standard Head Gasket and leave him having to work round it.

It's good to know that there is a pattern for the gasket in existance, and the thicknesses that they can provide from stock material - trying to get a copper or multi-layer gasket made in the UK can be difficult at best, or very expensive at worst - unless you want it for a Ford Escort.
Dave

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Re: 4XF1-WT project

Postby lotusflasherman » Sun 27.03.2016, 12:19

Chris and Dave,
I'm following this topic with interest... One of my first cars was a Lotus 6 that came with standard Ford 1172cc engine but I improved that with an Aquaplane head (standard gasket) and then, in a moment of madness, bought a secondhand Willment Overhead Inlet Valve Head with twin SU's - shown in photo
ohiv 10.jpg


Combustion chamber was a weird shape with a huge inlet valve directly over the piston, rocker operated, and using original side exhaust valve - it had virtually no torque till 4,500 rpm and then flew when the gases flowed but con rods were supposed to break at 6,500 so a ridiculously narrow power band. Such 'a rare animal' that I had to make my own gaskets out of soft copper sheets.
willment 03.jpg

The problem with the OHIV casting was the centre front and rear bolts holes (ringed in red) were very close to the combustion chamber edge so the gasket was really narrower in this area and used to burn away in a few thousand miles. When this happened the bolt hole would become part of the combustion chamber and I'd get a hissing out of the washers under the bolt heads causing a very strange noise and loss of performance.

Now, looking at the photo of the copper gasket for the Elan I see a very narrow section that might cause similar problems - shown it with red lines, and the more the bore increases the more likely it is to become a problem ...

Copper Head Gasket.jpg


I do notice that the marks on the block in Chris's photo shows the OE gasket has the same cutout but cannot see the reason for this and wondering why this has been copied onto the copper gasket. I've never had to remove the head from any of my Elans so am curious to know what the purpose of this big cutout is... do you have any photos of the underside of the head? Looking at just the block it appears a bolt hole and two small holes is all that's required in this locality and thus would leave a lot more gasket in this area. Just a thought ...
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Re: 4XF1-WT project

Postby John Syracuse » Mon 28.03.2016, 23:33

Dave,

Glad it was helpful. I installed the head gasket this weekend and based on turning the torque wrench compared to previous head gasket installations, it definitely feels like it compresses a lot less than the original. I didn't notice when getting to the first 29 ft lb step, but stepping from 29 to 58 only took a little less than an eighth of a turn! I'm used to closer to a quarter turn for that step.

Because of the ARP head studs, I torqued it a third step to 80 ft lb to finish it off. Supposedly you can go as high as 110 ft lb, but I'm not sure I believe the source for that and I'm aware of others who have torqued ARPs to about 70 to 80. And not to mention my torque wrench only goes to 75, I went an additional adjustment on it to get to 80, haha! We'll see how she holds! Pics below.

FYI, my block is definitely not decked, but it felt way smooth, I cleaned it really well with a razor blade and I'll bet it doesn't really warp also. We'll just have to find out how it turns out!

Phil,

That's a really good observation that I never even thought of on that distance to the cylinder bore until you pointed it out. If I do this again that'll definitely be something I'm going to have to think of. Luckily, one of the holes in that opening is a head stud, so it's getting compressed pretty well directly at the location. The jacket itself looks like it's for oil, I can't tell if it's a drain though from the head down back to the oil pan or if it's under pressure. Reason I'm having trouble is cause the underside of the block shows only one through hole going up through the head, but there are clearly two holes on the underside in the block, and the through hole is for the head stud, so no idea what to really think about it. Look at the pics below, maybe it'll help describe it. The little "ears" in the opening literally look useless. On the stock gasket there's a rubber ring in there. I put a red arrow showing where they would be on the underside of the head, hope that helps too.

Chris


Gasket sprayed with sealer.jpg


Block deck.jpg


Underside of head.jpg


Copper Gasket Ready for Install.jpg


4XF1.jpg


Stock head gasket.jpg


Up Close of Oil Jacket.jpg
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Re: 4XF1-WT project

Postby lotusflasherman » Tue 29.03.2016, 01:22

Chris,

photos very interesting. I see holes in gasket are a better match to holes in head than holes in block. Still can't see any reason for that big hole with 'ears' that gets so close to the bores. Think maybe next time leave the area shown in blue.

In the early '70's I went to a very interesting lecture by Harry Weslake (check wikipedia for his CV) who said " inlet manifold and inlet port should match exactly, as should exhaust manifold and exhaust port, but there's no point to it if the gasket isn't an exact match." Then he added "water and oil don't like obstructions that cause turbulence so other gaskets should be matched too". Maybe next time remove the area shown in red?


Ideal Copper Gasket.jpg
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Re: 4XF1-WT project

Postby dapinky » Tue 29.03.2016, 13:23

I'm loving all the thoughts on this one - plenty to think about....

.... which reminds me of an old discussion on the forum about head gaskets (when the general consensus seemed to be "Get the OE one, not a copy").

As part of that discussion, one of the points was "Why is the NA gasket a different part number to the Turbo?" - and I remember that the only real difference was the shape of some of the extraneous holes, but I can't remember which ones were affected. :oops: .

I seem to remember that aftermarket ones would fit to either engine, but Lotus ones were specific - maybe the pattern they have used here is a similar concept?

(This was a bit of a shame as at the time Lotus were selling off their remaining stock of NA gaskets for just £2 each, and I bought them all!)

Edit - I've now bothered to search the forum (before Enright tells me to use the bloody Search facility to avoid duplication :D )....

This thread is interesting, and gives links to a couple of further threads on Isuzone.com (even more to read - make a BIG cup of tea before you start!)...

...and gives a link to this one (which was the one I was trying to find)....

...which in turn leads to this one....

....but the bit which is relevant to here is probably the first post from Geoff linking to isuzu performance???

and as you will no doubt have got completely 'researched out' by now, have a look at another one :D

Much of the content is irellevant, as the OE ones are now availlable again from lotus (I still have a couple on the shelf), and the problems back then were of the "What can we now do to get round the lack of parts?" question.

To me, the issues are:-
1) What option do I have if I need to skim the head again (past the recomended levels in the Workshop Manual) - addressed by the current thread due to the possibility of copper gaskets in various thicknesses.
2) Will an OE gasket have a suitable cylinder bore size for a 1mm overbore to suit my new pistons? - only need to consider this if the thickness issue needs addressing anyway.

Either way, my choices are to use a genuine Lotus part, or get a suitable copper one regarding bore size and thickness (with or without worrying about the oil/waterway holes!).
Dave

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Re: 4XF1-WT project

Postby lotusflasherman » Tue 29.03.2016, 19:50

Hi Dave,

haven't worked my way through all the links you provided but already seen a few interesting things worth throwing in 'my two pennyworth'... before I go play 5 a side football.

I now see the purpose of the 'ears' in the OE gasket is to locate the inserted seal around what I presume to be an oilway. Therefore I think a solid copper gasket should have a cutout the shape of the inside of the inserted seal, not the outside with locating lugs taking it so close to the bores. Bit late for Chris but something to incorporate in the next one?

My SE on SORN has a Bill's Isuziperformance short shift gear selector so already know of Bill and Isuziperformance but whilst I may agree with him on using the correct head gasket, if you have a choice, I think he's talking out of his 'exhaust pipe' on the reasons why ..

Using a 1.6 liter Turbo or 1.8 liter head gasket on a 1.6 liter Non-turbo engine will result in engine temperatures too low for the oil to properly lubricate the engine, resulting in rapid bearing wear and engine failure.
Using a 1.6 liter Non-turbo or 1.8 liter Non-turbo head gasket on a Turbocharged engine will result in inadequate engine cooling, overheating, oil breakdown and lubricant failure, head warpage, cracks in the engine's water jacket, and destruction of the engine.


Head gasket controls overall engine temperature ?? huh??... What's the thermostat supposed to do then?

Head Gasket water holes can be used to control the flow up the block and through the head and correct any casting design errors if hotspots are occurring - generally waterways are smaller near the pump, getting bigger further from the pump. Too big near the pump and water takes the line of least resistance leaving the far end stagnant. Bit like setting up lockshield valves on your central heating radiators really.

I'm still looking for reasons why the SE/S2 should be different from the NA... more when I get back.
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Re: 4XF1-WT project

Postby John Syracuse » Thu 31.03.2016, 23:25

Thermodynamically, if the fluid flow rate is the same, I'm pretty sure turbulent flow provides better heat transfer than laminar, however the efficiency of the flow is not as good because of the additional turbulence. That said, I don't know if one can truly say one is better than the other without knowing what the objective is. I suspect what your lecturer really meant is that the turbulence slows the flow and increases the duty on the pumps, which is bad if you've designed it to maintain a certain flow rate, but I couldn't say for sure.

Truthfully though, I've read a lot on the whole using gasket hole sizes to regulate fluid flow and I honestly just don't buy it. That doesn't mean I can explain why gasket hole sizes don't always match, my best guess would be relating to manufacturing schedules for simultaneous parts and manufacturing precision. If you design an engine and start casting heads and blocks and sub-contract out the gaskets, you suddenly have a few hundred of them all in front of you and they don't all match when you start to put them all together, as long as the motor still works, why spend any extra money on a production fix? Especially if you're on a schedule to get the product out at a certain time, even more especially if the fix is something your main clientele generally isn't going to notice anyways, and especially, god forbid, if it means you have to throw out already manufactured parts. I work as an equipment engineer and that kind of stuff happens all the time where we put out designs that we know aren't the best, sometimes designs that we literally dislike or even hate ourselves. But they work and we're not paid to put together the best design or the design that's our favorite, that's too subjective a criteria. Engineers and manufacturers are paid to get a functional design or product out the door within a set budget and in a certain amount of time, depending on how quick they want it or how cheap it needs to be, the quality will correspond to it.

I guess that was a soap box write up, but to relate it to the point of the discussion on gaskets and the explanations people have online, I think a lot of people have the impression that every single feature and characteristic in a car is deliberate through severe engineering or testing and there's a large story and explanation behind it, and that causes people to try to backfill what the story is when they see something that doesn't make immediate sense and they can't come up with an explanation for it. Really unless they have true experience designing and manufacturing engines, I don't think they can have any certainty in what they're saying. That's not the case though, stuff gets designed and manufactured all the time with very little thought or attention to detail. (Look at the gas tank on the Elan, who was the genius who engineered that without thinking swaying and sloshing in the tank wasn't going to cause cracks?)

EDIT: It would be irresponsible if I don't say, I also can't say with any certainty why the gaskets and holes don't match since I'm included in the group of people who have never designed or manufactured an engine.

I didn't get a picture of it, but the ports on the head did at least match more closely to the head gasket, so I'm not going to worry about it. When I was still a Storm enthusiast, I'd done probably close to 10 head gaskets on different Isuzus and never worried about it then.

Chris
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Re: 4XF1-WT project

Postby John Syracuse » Sun 03.04.2016, 15:09

Just had a good find to the discussion of what each of these ports do through the head gasket.

In reviewing the shop manual for something slightly related, I was looking at Engine Lubrication diagram and reading the description. It appears that the flow to the head comes from the back of the motor between the 3 and 4 cylinder, oil flows up to a check valve in the head, from which oil is distributed throughout to the camshaft bearings, etc. If that's the case, that is the only oil jacket through the head where there will be high pressure, all the other oil jackets are returns and will not be under any pressure at all. This is the same location where the gasket has the mysterious "ears".

That being the case, of all of the locations where there is a rubber ring are oil jackets, they would only be returns to the oil pan and not under any pressure. That might explain why there would be low attention to detail at those jackets in terms of gasket to port matching - if it's served it's cooling purpose and is just gravity flowing back down to the oil pan at that point, obstructions aside, as long as it makes it back to oil pan, it's fine.

Figured since this information would be good to know.

The semi-related thing I was looking for which has been on my mind for as long as I've had this motor that I'm interested to hear opinions or experience about are the oil jets for the pistons. There's a notable difference between the lubrication designs between the turbo 4XEs and non-turbo 4Xs,... and then there's my 4XF...

For turbo 4XEs (described in the shop manual), piston cooling is provided through jets at the 1, 2, 3, and 5 crankshaft journals.

For all other 4Xs (Es and Fs, at least included in my copy of the shop manual), the oil for piston cooling is provided by individual jets on the connecting rods that hit the back of the piston.

From the diagrams for both types, it's implied that the piston oiling is also how the cylinder bores get lubricated. This is important when moving on to my (take your pick between "disaster" or "ultimate-chine") in the making - I have both custom forged pistons and connecting rods and the connecting rods were deliberately manufactured without oil jets in the connecting rods (i.e. there is no direct lubrication path to the pistons and implicitly the cylinder bores). When I first saw this and had my :wtf: reaction, I called up my bud who I bought this short block from and asked him what the crap? He told me he saw the same thing and had the same :wtf: reaction, called up Crower and asked them what the crap? Crower's response was that those jets become unnecessary if forged pistons are being used as they are more resilient to the heat loads of the engine. I can believe that the forged pistons are more durable and ready for the task, but I've still tossed and turned about whether that means it's okay for the cylinder bores, especially since mine's bored passed the shop spec. Maybe enough oil is flung onto it from the crankshaft as it's squeezing out of the rod bearings? That's not something I have any experience or judgment about though.

My online researching has found people with different motors have done the same thing, but I can't find anything definitely saying one way or another that there's a problem. The other factor I can't determine is how much it matters that the car is race-built vs. street-built. This engine and it's components were put together with racing in mind, but my application is intended to be street, I want to be able to road trip with the Elan.

I intend to try calling Crower themselves and hearing the whole explanation, but was interested to hear if anyone else has background, knowledge or a take on this that might help.

Chris
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Re: 4XF1-WT project

Postby dapinky » Sun 03.04.2016, 16:08

Chris,

I can't offer any insight into whether you will need the 'extra' oil squirting bits or not - part of me wonders why Lotus (actually, Isuzu) would have designed the bore lubrication system for the Turbo engine if it wasn't needed (as the Turbo had forged pistons to start with), whilst the N/A had cast pistons..... but this only relates to the 'standard' 4xE engine, I have no knowledge of the F varient.

Then i was thinking that as the Lotus version used hydraulic lifters (as against Isuzu solid ones), what effect does that have (if any) to the overall oil pressures at various parts of the engine.

My thinking is currently along the lines of:-

Oil in the sump is at 1 bar absolute (atmospheric pressure).
Goes through the pump and into the system at whatever pressure the pump puts out.....
...goes through the oil cooler, flow rates change, but the pressure shouldn't (well, not enough to worry about)....
....goes into engine block where it is under the same pressure...
....some goes to the crank oilways, some goes to the head...

...but the pressure remains the same whilst the system is 'sealed'....

Then it gets to the more complicated bit - in the head, oil has 2 jobs
1) to cool/lubricate the camshafts
2) to operate the hydraulic valves
Obviously, once oil has sprayed onto the cam bearings it's into an 'open' system and looses pressure, then falls back tot he sump under gravity - similarly, once the lifters are pressurised, excess goes 'open flow' and returns to the sump.

Meanwhile, in the block the oil has to lube the cylinder bores and the crankshaft -
The crank isn't a problem (as long as the bearings are good), so the only worry is getting enough oil into the bores to :-
1) assist cooling
2) stop the pistons/bores seizing (and reducing wear to acceptable limits).

As the only real contact between piston and bore is the rings, I cant see that the difference between cast and forged pistons has too much to do with the contact between the two (obviously, the material expansion is slightly different, and the forged one will take better mechanical attack with each ignition stroke)......

...which leaves me thinking that the extra oil spray on the Turbo engine is (partially) irellevant to the actual piston material, and I don't know why it is there ...........

........ but someone with far better understanding of all this decided it should be, so that's what I'm sticking with!

However, as I say - my knowledge of the 4xF engine is pretty thin - does it have the 'extra' holes in the crank/big end bearings to supply the oil spray? If it does, what is going to happen to oil pressures if the holes are 'blanked off' with solid bearings and/or rods? Will it lead to more oil getting splashed up the bores or less? I really don't know :?
Dave

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Re: 4XF1-WT project

Postby John Syracuse » Sun 03.04.2016, 19:52

Dave,

Appreciate the input. The turbo 4XE1 pistons are a mystery to me to some extent, which is funny cause I've actually held ones from the Impulse RS in my hand and I still don't know what to think.

The shop manual I have is for 1992 JI-Body (Impulse) Isuzus, which is AWESOME cause it covers the both turbo and n/a 1.6 DOHC 4XE1 motors AND the 1.8 DOHC 4XF1, so I can switch between the pages to compare differences between the two (or all three even, rarely a need to though) which is ideal for my application since there's Frankensteining involved in my project. Where it can be interesting is to read seeming differences between the 4XE1-WT of the Impulse RS and the 4XE1-MT of the Elan. When I look it up in the Isuzu manual I have, it states the pistons are cast. When you look it up in the Lotus Elan manual, it states the pistons are forged. I've heard Isuzu owners say both that the turbo 4XE1 pistons are cast and that they're forged.

What makes it ambiguous to me directly is that I've actually held the pistons for all three Isuzu engines in my hand. I really wish I had a picture of it now cause it's hard to describe it, because the pistons from a turbo 4XE1 taken from an Impulse were very clearly a higher quality piston than the cast ones from the non-turbos. They were machined very similarly to what you would see from a piston made from a forged billet, but at the same time the material and make of them fell very short of the quality of aftermarket forged pistons. I don't know if the pistons were forged or cast, my inclination is that they were forged, but either way if the turbo Elan pistons are the same as the turbo Impulse, I can say those pistons are not on par with an aftermarket forged set. I wonder if there's anyone who knows definitively if the pistons the same between the Impulse RS and the Lotus Elan?

If you asked me to take a guess, I suspect that the Isuzu manual calling them cast is a typo that was copied and pasted from the other sections of the manual and that they're really forged pistons. I would suspect the biggest difference between the factory and aftermarket forged pistons is the material, which would explain how a factory forged piston may still need the additional cooling that Isuzu provides. Either way, the 4XE1s and 4XF1s all provide cooling for the pistons, the turbo 4XE1 is the only one to have jets coming from the main crank bearings while all the others have the jets come from the rods. I know that with some forged pistons, it's actually possible to have them cooled too much that they don't expand enough, you'll have piston slap and they won't make a good seal. That's usually only with forged pistons for high-end race purposes only.

In my case, I'm not going to get anything dedicated for the pistons unless I take the rods back out and have the jets machined into them, but that goes back into the conundrum of whether the pistons will be over-cooled or not,... what a mess. As long as enough oil still gets "flung" up there from the crankshaft where it comes out at the rod bearings, it should be okay, but I also have no way of knowing. Doesn't look like I'm getting around asking Crower about it.

Chris
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Re: 4XF1-WT project

Postby dapinky » Sun 03.04.2016, 22:39

Chris,

I'd love to be able to give you an answer, but I'm learning far more from this thread than I'm able to contribute - I have never seen a piston from an N/A engine (Lotus or Isuzu), but can agree with you that good aftermarket ones appear far better than the factory ones. (well, the new Arias ones I got from the Isuzone group buy appear better than the old ones I've seen in knackered Elan engines!)
Dave

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Re: 4XF1-WT project

Postby lotusflasherman » Thu 07.04.2016, 03:18

Chris,
Seemed to have missed your updates on this thread…Interesting points you've covered in your last couple of posts.
Turbulent flow - I think very bad in a cooling system. Turbulence will cause a variation in flow and pressure and a drop in pressure can lead to spontaneous boiling of water in contact with the combustion chamber.
Oil way – ‘hole with ears’.. That makes a lot of sense and maybe explains why the bolt sits in the centre of that ‘oversize hole’. By sitting in the centre it will pull down the seal more evenly.
Your comment on ‘designing and manufacturing engines’… err, well, almost…
I’ve got a lot of experience with various engines, starting in my early teens with old motorcycles – I got hold of a Norton Dominator 650SS for nothing and my pals got Triumph Tiger 110’s which seemed a bit quicker. We were only ‘grasstrack racing’ on a large bit of wasteland so I stripped everything off, but in search of more power I found the “Design and Tuning of Competition Engines" by Philip H Smith in my local library and got addicted.
My sister, older by 4 years, bought a Ford 100E Anglia with 1172cc sidevalve engine but let it freeze up in the winter of ’63 and the head bent. I helped out by buying Mr Smith’s “The Ford Ten Competition Engine” and UK magazine ‘Cars and Car Conversions’ that had a series of articles on tuning that engine, and others; adverts from major tuning companies and a huge ‘For Sale’ section at the back, and we bought a complete engine with every Aquaplane upgrade on it. That left me with the ‘headless engine’ to play with so I polished the crank, lightened, polished and balanced the con rods and pistons and then bought a Willment OHIV head, so I had a ‘state of the art’ competition engine. Put it into sister’s car and within a few hundred miles it took the teeth off first gear – Oops! Bit tricky when the car only had 3 gears to start with. Sister bought a Mini while I was sorting that out but said she preferred the Mini if I could make it go faster, which I did.
One of her boyfriends was ‘an upper class twit’ with a Healey 3000 and a Formula Junior car and he asked me to help rebuild the Weslake BMC A series engine in that. My first look inside a professionally produced race engine. Interesting to see the oil pump and oilways into the block had ‘been flowed’, lobes on the water pump reduced and a really BIG pulley on the dynamo. The head was everything Mr Smith had said it should be.
When I became old enough to drive, the 100E went back on the road with the Aquaplane engine and 4 speed gearbox and once I’d passed my test I went looking at Lotus 7’s with 1172cc engine. Found a Lotus 6 going cheap as it had been used for organised grasstrack racing using a “Holbay 997cc ‘screamer” that had put a rod through the block. Had an aeroscreen, no windscreen, no wipers, sidescreens, hood or heater and had a 7 rear axle / suspension arrangement rather than the torque tube / panhard rod of the 6. Put the Wilment OHIV engine in the 6 for a lot of fun in the summer and in the autumn started to dismantle the Holbay engine to see what parts I could sell. That was very interesting.
Went to Brands Hatch to mechanic for ‘upper class twit’ and in the paddock we were next to some guys from close to home who were racing a Mini for the first time. I got chatting and we arranged to meet in a local pub. Spent a few weeks sharing ideas about engines and formed a two car team for next season and with our home-made engines were consistently on the podium and won the 1000cc Mini Miglia Championship a couple of times between 1971 and 76. The 998cc engine we used came out the factory with 38 bhp and we were getting mid 90’s at the wheels on a rolling road. Lots of copied ideas but most of what we did I found in Mr Smith’s book. I bought an updated 6th Edition (1977) when it came out as it had added a section on Turbochargers.

I’d recommend that as essential reading for anybody going into uncharted waters -
www.ebay.com/itm/NEW-The-Design-and-Tuning-of-Competition-Engines-by-Philip-H-Smith-Paperback-Bo-/391420428499
Uk ebay here for Dave – http://www.ebay.co.uk/itm/The-Design-an ... 1541015829

I put 130,000 miles on my first SE and 40,000 on the next two so done 170,000 Elan miles but never had the head off an 4XE1 engine so I’m no help on anything specific on that. Tried looking at the pictures in the Service & Parts Manuals but they don’t give me the detail I need.

On the subject of oiling the bores –the majority of longstroke bike and car engines had a big end shell with a hole to let oil up the rod’s oilway. Some had pressure feed to the small end as well as spraying the bores.
Short stroke and high revving competition engines usually have a solid con rod without oilway as this would weaken it so they rely on oil mist spray lubrication. Also race engines, usually, have bigger bore clearance, more piston slap, and rely on ring sealing.

I was trying to find some info in Smith’s book but quite a while since I read it, though I did come across something in the chapter about the Cosworth BDA (page 434) that I found ‘interesting’.. – “Cosworth engines in kit form have pistons with only partially machined crowns. These can be machined to achieve any desired compression ratio. However, at ratios of 12:1 or above it is necessary to use ‘O’ rings around the cylinders in addition to the normal sandwich type cylinder head gasket.”
The Elan Turbo mechanical CR is 8.5:1 but increased by standard turbo boost of 0.65 bar (0.64 atm) so when on full throttle and full boost the CR would end up at 8.5 x 1.64 = 13.95. There may be induction inefficiency that restricts that a bit but it looks like the standard head gasket is already ‘sailing close to the wind’. Wondered why so many head gasket failures appear on the forum.
Perhaps I won’t increase my boost.

There's also a few pages in Smith's book discussing pistons, materials and surface finishing and what's best for oil retention for lubrication...
Phil

Leave me alone, I think I know what I'm doing.
Cars: Subaru Forester 2.5XTN, Eclat Riviera, brace of Pacific Blue SE's, Elan+"S.... and now a Collapso SE
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Re: 4XF1-WT project

Postby John Syracuse » Sat 09.04.2016, 03:25

lotusflasherman wrote:Chris,
Seemed to have missed your updates on this thread…Interesting points you've covered in your last couple of posts.
Turbulent flow - I think very bad in a cooling system. Turbulence will cause a variation in flow and pressure and a drop in pressure can lead to spontaneous boiling of water in contact with the combustion chamber.
Oil way – ‘hole with ears’.. That makes a lot of sense and maybe explains why the bolt sits in the centre of that ‘oversize hole’. By sitting in the centre it will pull down the seal more evenly.
Your comment on ‘designing and manufacturing engines’… err, well, almost…
I’ve got a lot of experience with various engines, starting in my early teens with old motorcycles – I got hold of a Norton Dominator 650SS for nothing and my pals got Triumph Tiger 110’s which seemed a bit quicker. We were only ‘grasstrack racing’ on a large bit of wasteland so I stripped everything off, but in search of more power I found the “Design and Tuning of Competition Engines" by Philip H Smith in my local library and got addicted.
My sister, older by 4 years, bought a Ford 100E Anglia with 1172cc sidevalve engine but let it freeze up in the winter of ’63 and the head bent. I helped out by buying Mr Smith’s “The Ford Ten Competition Engine” and UK magazine ‘Cars and Car Conversions’ that had a series of articles on tuning that engine, and others; adverts from major tuning companies and a huge ‘For Sale’ section at the back, and we bought a complete engine with every Aquaplane upgrade on it. That left me with the ‘headless engine’ to play with so I polished the crank, lightened, polished and balanced the con rods and pistons and then bought a Willment OHIV head, so I had a ‘state of the art’ competition engine. Put it into sister’s car and within a few hundred miles it took the teeth off first gear – Oops! Bit tricky when the car only had 3 gears to start with. Sister bought a Mini while I was sorting that out but said she preferred the Mini if I could make it go faster, which I did.
One of her boyfriends was ‘an upper class twit’ with a Healey 3000 and a Formula Junior car and he asked me to help rebuild the Weslake BMC A series engine in that. My first look inside a professionally produced race engine. Interesting to see the oil pump and oilways into the block had ‘been flowed’, lobes on the water pump reduced and a really BIG pulley on the dynamo. The head was everything Mr Smith had said it should be.
When I became old enough to drive, the 100E went back on the road with the Aquaplane engine and 4 speed gearbox and once I’d passed my test I went looking at Lotus 7’s with 1172cc engine. Found a Lotus 6 going cheap as it had been used for organised grasstrack racing using a “Holbay 997cc ‘screamer” that had put a rod through the block. Had an aeroscreen, no windscreen, no wipers, sidescreens, hood or heater and had a 7 rear axle / suspension arrangement rather than the torque tube / panhard rod of the 6. Put the Wilment OHIV engine in the 6 for a lot of fun in the summer and in the autumn started to dismantle the Holbay engine to see what parts I could sell. That was very interesting.
Went to Brands Hatch to mechanic for ‘upper class twit’ and in the paddock we were next to some guys from close to home who were racing a Mini for the first time. I got chatting and we arranged to meet in a local pub. Spent a few weeks sharing ideas about engines and formed a two car team for next season and with our home-made engines were consistently on the podium and won the 1000cc Mini Miglia Championship a couple of times between 1971 and 76. The 998cc engine we used came out the factory with 38 bhp and we were getting mid 90’s at the wheels on a rolling road. Lots of copied ideas but most of what we did I found in Mr Smith’s book. I bought an updated 6th Edition (1977) when it came out as it had added a section on Turbochargers.

I’d recommend that as essential reading for anybody going into uncharted waters -
www.ebay.com/itm/NEW-The-Design-and-Tuning-of-Competition-Engines-by-Philip-H-Smith-Paperback-Bo-/391420428499
Uk ebay here for Dave – http://www.ebay.co.uk/itm/The-Design-an ... 1541015829

I put 130,000 miles on my first SE and 40,000 on the next two so done 170,000 Elan miles but never had the head off an 4XE1 engine so I’m no help on anything specific on that. Tried looking at the pictures in the Service & Parts Manuals but they don’t give me the detail I need.

On the subject of oiling the bores –the majority of longstroke bike and car engines had a big end shell with a hole to let oil up the rod’s oilway. Some had pressure feed to the small end as well as spraying the bores.
Short stroke and high revving competition engines usually have a solid con rod without oilway as this would weaken it so they rely on oil mist spray lubrication. Also race engines, usually, have bigger bore clearance, more piston slap, and rely on ring sealing.

I was trying to find some info in Smith’s book but quite a while since I read it, though I did come across something in the chapter about the Cosworth BDA (page 434) that I found ‘interesting’.. – “Cosworth engines in kit form have pistons with only partially machined crowns. These can be machined to achieve any desired compression ratio. However, at ratios of 12:1 or above it is necessary to use ‘O’ rings around the cylinders in addition to the normal sandwich type cylinder head gasket.”
The Elan Turbo mechanical CR is 8.5:1 but increased by standard turbo boost of 0.65 bar (0.64 atm) so when on full throttle and full boost the CR would end up at 8.5 x 1.64 = 13.95. There may be induction inefficiency that restricts that a bit but it looks like the standard head gasket is already ‘sailing close to the wind’. Wondered why so many head gasket failures appear on the forum.
Perhaps I won’t increase my boost.

There's also a few pages in Smith's book discussing pistons, materials and surface finishing and what's best for oil retention for lubrication...


Phil,

My comments weren't directed at you. I've read some of the forum threads where people make speculations on things similar to why gasket ports strangely don't match, and I just feel there tends to be a lot of people trying to force fit technical answers when it's probably something much less technical and arbitrary. Again, I work designing mechanical equipment and we make arbitrary engineering decisions all the time that have little basis beyond "It works and we don't have time/budget/need to think about it anymore than that." I chalk up the mismatched ports between heads and engine blocks to arbitrary engineering decisions, it actually makes more sense to me that way than it being a deliberately engineered design feature.

With respect for turbulent flow, I don't think what I said necessarily disagrees with what you said, but just very generally speaking, laminar flow can't always be said to be better than turbulent without knowledge of the application or condition. An entirely different application, I was involved in designing an equipment enclosure for a very high temperature application. We had to equip the enclosure with interior heat shielding with active gaseous flow behind the shields in order to keep the enclosure from reaching temperatures that would burn any operators. In that design, we had to ensure that gas flow was always turbulent because laminar would not cool the surfaces fast enough to reach the design temperatures. Again, an entirely different application, but that application required an entirely different operating condition.

I've just about stopped worrying about the oil squirters being deleted from the forged rods I've got, but I haven't talked to Crower yet. I did however consult a bit with another buddy of mine who also fixes up Isuzus as well as other cars, he's also a mechanical engineer, and he's confirmed that there are several examples of vehicles that don't use anything but oil slinging from the crank to keep anything on the cylinder bores and that some of his hobby cars are that way from the factory, it's really piston cooling where it becomes necessary. I would expect race engines have bigger bore clearance than other engines, those applications require higher durability alloys for their pistons which also have higher thermal expansion rates. The problem of piston slap in building a factory engine for a race application is if the design uses oil to cool a lower cost/quality factory pistons (as is the case with the 4XE1 and 4XF1), if you leave it that way when you add a forged piston made from an allow for high-end race applications, you cold be in a situation where the oil squirters make it worse cause you need the piston to expand enough to seal.

My first experience with turbocharging was actually bolting up the Impulse RS turbo to my Geo Storm, which at the time was equipped with the n/a 4XE1, so it's compression ratio was 9.8:1. I turned that one up to about 14 psi, so it's effective compression ratio at full boost was over 19:1, and that head gasket never blew. I think there's probably more to it, even so I'm not going to worry with the copper head gasket and ARP head studs. Piston failures in the 4XF1 are what I've experienced,... twice.

And regardless, increasing the boost = fun! Not increasing the boost = less fun,... So turn up the boost!!!

Chris
f.k.a. booster on Geo Storm and Isuzu forums of yore.

Love is fleeting, POWER is eternal.
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