Forget 24v, m20 powahhhhh is where its at!!!!!

[maggspower]

the stock head flows well looking from a stricktly flow point of view but the flow stalls when you start moving alot more air, its easily fixed but big strokers power do nose over quite early if not addressed particularity with OEM intake which exacerbates the issue.

Dudes in sheds are good but you need to find the right dude....
my current head was "machine" ported and finished by hand so its consistent but the issue is its just not just very good compared to whats possible. the new head was done by a dude in a shed and its miles better i'm slowly getting closer to actually being able to bolt it to a bottom end.....

Well we both know the stock inlet is probably the most limiting factor of the engine when stroked.

This one is still making power a 6875rpm when it hits the soft cut rev limiter, so more revs will equal more power, but that was not what it was built for. Retaining drivability is more important on this one. You tend not to spend very long at 7k rpm in a road car, so power up there is not what makes it feel fast.

The right dude is the one you need, for sure

[reggid]

What cam is it running? With the head and inlet sorted I think you can use less duration than people tried in the past. I remember one guy using a dbilas 312 cam stock valves and intak, and it didn't raise peak hp rpm over what something in the 280s would give as there was obviously it could not move more air due the head going turbulent

[maggspower]

Ok tonights update, I can't find any painting or boring pics. I'll put them in later.

So we'll start off with the new pistons fitted into the block, this is a dummy build, where you put all the bits you have together to make sure they fit. There is nothing worse than trying to put something together only to find, it doesn't fit, has been machined wrong, or is just not what you ordered, it happens, assume its wrong until you know otherwise

And Gryff the security



The cylinder and piston crown are then measured the same way as the cylinder head. From this can be determined the static compression ratio, and how much is needed to come off the cylinder head to adjust it to the desired C/R.





Now one of the best tools in the shop, the Colchester Student lathe, from 1966 This is an great example, took me a long time to find one this good. Anyone that has had a BBTB off me its been done on this. The reason for the picture is that it is clean here, it gets messy quickly



So with the block dummy built, I could see there was a problem with the oil pump drive, it sat too close to the con rod so this was cut down to add some clearance.



And I made the oil seal/spacer, for the crank nose.









Hmm, not my finest machining on the end there I must admit, but the important bit is the outer circumference which is as it needs to be.

[reggid]

did you use high tensile steel? ive seen el cheapo ones wear a groove real quick and leak the seal manufacturers usually recommend 35+ HRC. that rear face just has seal to the crank to stop oil getting up the snout i think i used some loctite product on the face

[maggspower]

I have just looked, and the H/T steel used was at 32.2 on the rockwell scale, a little lower than you suggest, but I'm certainly not expecting it to leak any time soon.

I always use a sealant on the back side, Permatex is my current favorite, but is hard to get hold of.

[reggid]

That's fine I checked and the SKF site says 30HRC for standard lip seals, my memory was wrong

[ezagood]

ive spent a fortune on my m20 but im nowhere near that power. getting it mapped tomorrow with fingers crossed

[Jookeone]

My dad has a Colchester Bantam, brilliant bit of kit... Likewise it's rarely that clean

[maggspower]

ive spent a fortune on my m20 but im nowhere near that power. getting it mapped tomorrow with fingers crossed

Thats good, did you find some one with a rolling road?

[maggspower]

My dad has a Colchester Bantam, brilliant bit of kit... Likewise it's rarely that clean

I truly believe, in good condition, the old manual stuff is better. CNC is a different ball game though. I have a mate that I take stuff I can't do, and he does military and F1 stuff, football pitch sized workshop full of CNC gear But theres only about 20 people working there.

The machines are taking over!

[ezagood]

ive spent a fortune on my m20 but im nowhere near that power. getting it mapped tomorrow with fingers crossed

Thats good, did you find some one with a rolling road?

No. I'm going with ms2 tuning. Everyone else I have tried don't seem to want to do it. They have access to a dyno so I'm going to see if I can at least get a power run.

[maggspower]

ive spent a fortune on my m20 but im nowhere near that power. getting it mapped tomorrow with fingers crossed

Thats good, did you find some one with a rolling road?

No. I'm going with ms2 tuning. Everyone else I have tried don't seem to want to do it. They have access to a dyno so I'm going to see if I can at least get a power run.

You should be ok then, there was no mention of a dyno on their website. Good luck with it

[Jookeone]

My dad has a Colchester Bantam, brilliant bit of kit... Likewise it's rarely that clean

I truly believe, in good condition, the old manual stuff is better. CNC is a different ball game though. I have a mate that I take stuff I can't do, and he does military and F1 stuff, football pitch sized workshop full of CNC gear But theres only about 20 people working there.

The machines are taking over!

Defiantly, and for the same reason we all drive old E30s, it's more enjoyable and satisfying using the old stuff! Just a bit more limited when compared to modern CNC.

[maggspower]

Ok time for an update....... Off on a bit of a tangent today.

Throughout the build there was plenty of times when we were waiting for, and simply trying to find bits suitable for the project, there was never nothing to do though

Time for the previous engine to be lifted out of the bay. Getting the back end as high as possible is the key to doing this easily, and not touching the slam panel, much easier with a ramp. Load leveler for the crane also helps.





The car a whole has been well looked after, but also enjoyed. Its in really good condition with regards to the bodywork for an unrestored example, but with the engine out there were a few isolated areas that looked like they needed some attention, and this was the perfect opportunity.

First a strip down and clean.



And some of the problem areas.











The problem bits were addressed of which there were very few, some new metal welded in and some holes plugged. Then the surface rust dealt with. This was sand blasted off, the only real way to do it. No lotion or potion, or paint on jollop, does this job to last. The bits that look like grey primer are bare metal after blasting.









As you can see, the media blasting gets right into the corners that rust gathers in, and removes it perfectly.

After a good few days work, finally ready to be sent off to the painter, for a new coat of Royal blue metalic

[maggspower]

So at the painters, the suspension was stripped off and every last clip and fitting removed. The bare metal was primed to avoid any flash rust during the prep work.



Fully prepped masked and primed.



Base coat done.



And finished with clear coat.



A lot of work to do right, an engine bay is a real pain to prep and paint because of all the facets to it, but the end result is worth it

Anyway enough of this painting nonsense, I'll get back to doing some engine work in the next installment

[maggspower]

Ok then back on with some engine work. Today lightening, and balancing. A really important part of the build this, I wanted this engine to rev well, and having a light bottom end is one of the keys to this, we don't need to go mad as its a road car, it wont add power but it will help to make the most of what is there.



The lathe called into action again.



The chosen rods for this build, m52 forged numbers. These are really nice rods, it would have been easy to get some cheap chinese rods for this build, they can handle the power and revs, theres very little wrong with them, but OEM wins sometimes. I much prefer the shape of the BMW rod for a high revving N/A build. Throw them in standard? No



All the rods had a little lightening off the big ends, and the little end too. Note the removal of the "ears" on the small end. All this adds up.

Forge line is then removed on the "I" beam part and polished, all the way round the small end.



The rotating assembly is then sent off for balancing, crank, flywheel, clutch cover, and front vibration damper.



While this is off getting done, the rods and pistons are balanced. All the pistons are set to match the lightest one, the rods are balanced end to end, then paired up with a piston. This way its possible to get every single bit bang on, not just within a gram

Heres an eye opener.

Original piston and rod:



1172g

New forged piston, and lightened OEM rod.



944g

Thats a weight saving of 228g per cylinder assembly. X that by 6= 1368g plus the 2500g off the fly wheel. Thats approaching 4kg a massive improvement over a standard 325i

Material removed here, weight for weight, has a much greater effect on acceleration than throwing out your back seats!

[jimbom30cab]

Best thread on the zone for years !!

[maggspower]

Best thread on the zone for years !!

Haha, I don't know about that Jim, but thanks

[bab-91]

Wibble!

[Rav335uk]

Fucking hell Byron, I thought you were only a Farmer boy...

[maggspower]

******* hell Byron, I thought you were only a Farmer boy...

My other car is a Massey Furguson

[youtube][/youtube]

[Karan]

Great work

[steve_k]

Best thread on the zone for years !!

Haha, I don't know about that Jim, but thanks

he is right though byron,

great to see the m20 getting the attention it deserves instead of the normal "throw an m5x in there" type thread.

can't speak for anyone else but i think this (type of) thread should be stickied because it goes into detail on how to build a proper m20.

[Gert_8]

******* hell Byron, I thought you were only a Farmer boy...

My other car is a Massey Furguson

[youtube][/youtube]

Wales at its best!!

[Rav335uk]

Is that you cab Gerty?

[Gert_8]

No, my cab drives and sounds like Maggspower's tractor...

[Daveaholliday]

I have just looked, and the H/T steel used was at 32.2 on the rockwell scale, a little lower than you suggest, but I'm certainly not expecting it to leak any time soon.

I always use a sealant on the back side, Permatex is my current favorite, but is hard to get hold of.

Permatex.

Gotta love that stuff.

[jonny323i]

for £50 hes doing all this to mine next haha

[Kedge]

Awesome work as ever Byron.

[reggid]

any reason you chose those domes on the Ross pistons vs OEM style?

what cam do you run and does it idle well?

[maggspower]

any reason you chose those domes on the Ross pistons vs OEM style?

what cam do you run and does it idle well?

Lets just say for arguments sake the pistons chose me.

The car idles almost perfectly when cold, and perfectly when warm.

[reggid]

any reason you chose those domes on the Ross pistons vs OEM style?

what cam do you run and does it idle well?

Lets just say for arguments sake the pistons chose me.

The car idles almost perfectly when cold, and perfectly when warm.

i guess that's just how they come then?

[motormanmick]

Forge line is then removed on the "I" beam part and polished, all the way round the small end.



Awesome thread for anyone doing their own performance build, we used to do the same to rods for chevvy's before I saw the light and went to e30's. We also got them shot peened and heat treated as well as extra insurance. Very enjoyable read, keep up the great work.

[maggspower]

On with a bit more building then, shall we...........

More clearance issues to be dealt with. This time the conrods run into the lower part of the bore, so this was relieved to allow them to pass. This can be seen on the inside of the crank case.



The next job was sorting out the rings, the pistons came with a conventional set, plain, napier second, and sprung oil control.



Being custom made, the rings need to be filed to fit the bore. This can be a long process of taking the ring in and out of the bore, measuring and filing, the rings can be quite fragile, and you only have one chance to get it right. It can take a while, The top and second both need to be done.

To aid this I made a ring squaring tool out of a lump of nylon for this bore size. You put the ring in the bore........



Then push it down with this, that way the its in there square and the end gap can be checked with feeler gauges.



The rings start having a cross over within the bore, the gap corresponds to a formula using piston diameter as its variable.



This is the type of ring file I have used for years.



I have never really liked it, its slow, also inaccurate i feel, and at the time its abrasive diamond wheel had seen better days. So one of the twelve rings was gapped, then on the second one................ ummmmmm, this happened



It was a strange feeling, initially, I laughed, then had a Basil Fawlty moment..... Ring filer went out the window, never to be used again

Then it dawned on me, these rings are from the USA.......... The car is in the rollers in three weeks

So, I set about designing a new filer, one I was happy with, an electric one This design and making process did not get far, as I looked over and saw the abrasive wheel on the valve grinder, so I tried it out......... I'm doing the left hand bit of the ring here, the other side is not touching the wheel.



It worked perfectly, I was worried about keeping the ends of the ring square, but its not an issue. Its much faster, more controlable, and needs less pressure applied.

Just needed to remove the burr with a very small hand file.



This left me with 11 perfectly filed rings, a piston ring in America, and three weeks to finish building, fit, and run in an engine........................

Can it be done....... Find out in the next episode

I am confident the busted ring was a fault within it by the way. My story and I'm sticking to it

[motormanmick]

I am confident the busted ring was a fault within it by the way. My story and I'm sticking to it [/quote]

100% agree, faulty materials, happens to me all the time.

great idea about the bench grinder for filing the rings.