Airbox static flow CFD analysis

I did back to back testing on a rolling road with and without my Pipercross PX600 airbox. It turned out with the airbox fitted the engine lost almost 20 rear wheel horses! I desperately need to find a new solution to kill intake noise, and in order to do that I need a better understanding of what made the Pipercross airbox a bad performer.

On the rolling road we tested three scenarios. With airbox and filter, airbox without filter, and without airbox without filter. The filter did no difference what so ever, but with the airbox the difference was huge above 4000 rpm and up. We had problems with wheel slip on the rollers so the accuracy of the performance loss is low, but it is safe to say at least 15 rear wheel horses and probably more.

So CFD to the rescue. Or is it? This is not my home turf, this is me on a journey. I now know that this kind of static analysis is close to worthless. The difference will be huge in real life with valves opening and closing causing pulses that interfere with each other. I suspected that from the beginning but now I know for sure. I hesitated before publishing this post.

Anyway, I find this fun and interesting. And cool! But that's me. :-)

How I did the simulations

I used Autodesk CFD 2017 with the "old" solver. Advection scheme 1.

All simulations are made with a total flow of 420 cfm (ft^3/minute) on the supply port. (*)
An engine consume about 1.5 cfm per produced horse power [1] so a 280 hp engine requires 420 cfm of air.

I have set a pressure constraint of -28 in.H2O on all cylinder ports, and a flow volume constraint on the supply port. The idea is that all cylinders "suck" the same amount, and the cfm constraint will solve the pressure/velocity on the air supply port. Again, this is not my field of expertise, but I can't figure out a better way?

Then I run the simulation until convergence, run mesh adaption, and one more run until convergence. I used result planes with the bulk tool to calculate flow value results.

(*) I use these awkward units because that is what is commonly used in engine literature. At least the literature I've read.

PX600 airbox

First model is a rough model of my Pipercross PX600 airbox with a 90 deg silicon bend, as currently fitted to my car. As I wrote above, this box performed very badly on the rolling road test.

I started with a max flow simulation to see if the box suffocated the engine. It does not. It wouldn't surprise me if it could supply enough air for a Formula 1 engine. That is definitely not the problem.

Then I did the 420 cfm simulation as described above.


From left to right: 22%, 25%, 28%, 24% of air. If I recalculate this to air/fuel lambda it would be equal to: 0.74, 0.82, 0.93, 0.80, while the lambda sensor in the collector would read 0.82.

Here it is clear that the amount of air to each cylinder is not equal. If we don't use individual cylinder fuel trim the air to fuel ratio will be very different for each cylinder. That is not only killing performance, it could even be disastrous for a knock sensitive high compression engine! [2]

Second model is the same Pipercross PX600 airbox without the 90 deg silicon bend.

From left to right: 23%, 25%, 27%, 24% => lambda 0.77, 0.84, 0.89, 0.80.

A lot better. The silicon bend is not helping! But it is clear that the sharp turns into the trumpets are problematic.

R500 Caterham airbox

Third model is the R500 Caterham airbox. The measurements are just rough estimates taken from a few pictures I found on the internet and probably not very accurate.

From left to right: 32%, 23%, 22%, 23% => lambda 1.04, 0.76, 0.71, 0.77.

Nice looking box though. I do think my cad model could be improved and that could result in different results especially into first trumpet.

Own design #1

So I realized airbox design isn't easy. I figured I'd need more volume in order to slow the air down. I also realized that I could build a bigger air box if I was having the entry tube facing rearwards.

This is an attempt to slow the air down before the first trumpet, still withing the space constraints of my bonnet. I know, it isn't pretty.



From left to right: 27%, 25%, 23%, 24% => lambda 0.90, 0.83, 0.76, 0.79.

OK not bad, but still...

Own design #2

Next attempt was with smoother curves in an attempt to guide the air into first cylinder. Pretty nice looking if I may say!

From left to right: 29%, 25%, 24%, 22% => lambda 0.96, 0.82, 0.79, 0.72

That didn't work very well. Feeding an engine from the side is tricky business.

Conclusion

Again, a static flow analysis doesn't say anything. But one thing it shows very well is how difficult this is. In particular how hard it is to feed air to an engine from the side! I suspect that the only thing that works ok is individual fuel trim or air boxes with enormous volume.

I did a quick test with a transient simulation. Lets see if I follow up on that or if I spend my time on better things.

Sources:
[1] Engine Airflow, Harold Bettes, HPBooks
[2] Four-Stroke Performance Tuning, A. Graham Bell, Haynes

Cool spark plugs

From recommendations I've always used NGK BR7EFS spark plugs - with heat range 7.

After a rolling road session I was told to use a cooler spark plug as the insulator nose was chalky white all the way up after a full throttle sweep.

A too 'hot' spark plug has less cooling, causing the plug to run hotter. On a road engine in traffic this is preferred but on full throttle it can get too hot and become a glow plug instead of a spark plug. Car manufacturers compensate for this with more fuel that cools the plug. On a race engine we can prioritise differently.

As 'cooler' plugs transfers more heat to the engine top it instead lowers the temperature of the tip of the spark plug and allows a more optimum air/fuel ratio on wot without overheating, and a overheating spark plug can cause pre-ignition which is disastrous for an engine. On the flip side are possible troubles starting when cold and carbon fouling when the engine is used at low speed. Very extreme engines even use two plugs with different heat ranges. If any of this will be a problem for me we'll see, but too cold is better than too hot in order to avoid engine damage.

As NGK doesn't manufacture a similar but cooler BR8EFS plug, I had to switch to Iridium. As a bonus iridium plugs require less voltage to fire and therefore allow wider plug gaps, which in turn gives a more stable combustion and less risk of miss fire.

Denso IT24 was cheaper than NGK TR8IX, and Denso is also what SBDev recommends. So I ordered a set from eBay.

Sources:

• Four-Stroke Performance Tuning, 4th edition, A. Graham Bell
• http://www.sbdev.co.uk/Duratec/Electrical%20components.htm
• https://www.ngk.com/Spark-Plugs-NGK-c593.aspx

VCT Delete

Using aftermarket cams on a VCT Duratec head requires that the VCT valve is removed. Unfortunately this opens up an oil passage which must be blanked, and doing so without eliminating the oil supply to the no 1 cam journal.

This is also known as "VCT Delete", and hardware for this can be bought from massivespeedsystem.com in the USA.

But importing stuff from the USA is not very cheap after adding postage, VAT and customs, so here is a sketch for a DIY solution.

I went to a local mechanic in the neighbourhood and got this part manufactured in aluminium.

Glued it in place using Loctite for cylindrical bonding. It won't take any load, in fact the oil pressure will generate forces in both directions and keep it in place by itself. But just to be sure, I made a punch mark that definitely will keep it in place.

Duratec Front Pulleys

Some of the more recent Duratec versions uses a larger front pulley trigger wheel than before. The trigger wheel diameter must match the style of the engine front cover, at least if you plan to use the standard crank sensor and mount.

Also, if the pulley size is large on high rpm engines it may cause the alternator to over-rev, and the water pump could experience cavitation that causes cooling problems. It is also said that unnecessary power is lost. For these reasons aftermarket under-drive pulleys are available in various models.

On the picture above there is to the left a 164mm under-drive pulley, in the middle a stock 146mm old style pulley, and to the right a stock 164mm pulley.

Aftermarket underdrive from TTV Racing.
Weight: 776g
Trigger wheel: 164mm
Pulley: 100mm
Alternator rpm @7800: 13000 rpm.
Waterpump rpm @7800: 7428 rpm.

Stock old pulley
Weight: 1529g
Trigger wheel: 146mm
Pulley: 137mm
Alternator rpm @7800: 17810 rpm
Waterpump rpm @7800: 10177 rpm

Stock large pulley
Weight: 1949g
Trigger wheel: 164mm
Pulley: 155mm
Alternator rpm @7800: 20150 rpm
Waterpump rpm @7800: 11514 rpm

The alternator pulley above is 60mm, water pump pulley 105mm.

According to the book Four-Stroke Performance Tuning by A. Graham Bell, a water pump's maximum efficiency zone is usually between 4000-6000 rpm.

A good article/calculator addressing how the pulley weight affects power output can be found here: http://hpwizard.com/rotational-inertia.html#flywheel

Cranks and rpm limit

A Duratec 2.3 engine can safely be revved up to 7200 rpm with the standard valve springs. With uprated springs it the limiting factor is the crank and according to Cosworth it can be revved up to 7700 rpm with the standard crank. Above that, a very expensive steel crank is needed. (source)

Balanced crank and front pulley

Among other places, a thread on Pistonheads several people writes that the standard crank may be up for more than 7700 rpm. On my engine the power curve was still climbing when I hit the rev limiter and I would probably gain some top end power if I could raise the RPM limit to say 8000.

What kills a crank is not power or torque, it is RPM. The force on the crank is exponential to the rpm. (source missing) That's why forced induction engines can have very much power and still use the standard crank, as long the rpm limit is kept down. Apparently the forces are specially high during downshifting.

I wrote an email to a Ford Focus engine builder and asked about their view on the subject.

"For us we have a race car and we redlined it at 8500 with no problems ever. But the engine was balanced and we even balanced it with the flywheel and clutch to make sure it was perfect! It can be done but just take all precautions needed..."

I did a simulation in Optimum Lap and a 8000 rev limit would do about 0.5 seconds on Mantorp. Not much and I'm doubtful it is worth the extra risk and engine wear, but as my engine is in pieces I went to a engine workshop anyway to have my crank, pulley, flywheel and clutch balanced. It doesn't cost much and it would decrease the loads on the bearings even if I increase the rev limit or not. I also hope it would reduce some vibrations at high rpm making it easier to stay focused on the race track.

Balanced clutch and flywheel

The mechanic explained they put the crank in their machine and start rotating the crank and measuring the imbalance. After some adjustments by removing metal the balance "was zero" and he put on the flywheel and balanced again. Then the clutch and finally the front pulley. That way individual components can be replaced without the need to rebalance the crank. On V engines the weight of the crank counterweights depend on the weight of the rod and piston. That is not true for inline-4 engines as there is always the same weight going the opposite direction. (as long as the piston/rod assemblies are of equal weights, which they normally are if bought as a set)

More very informative reading about cranks here.

Engine damage

Bad start this year. 

The fuel surge on last trackday caused more damage than I initially thought.

Damaged spark plugs. These are from cylinder #2, #3 and #4

A compression gave the figures 14.5, 12.5, 12.0, 13.5 bar and they're supposed to be within 10%. Some oil in the bad cylinders increased the compression quite a lot. According to Google that puts the suspicion to damaged piston rings. I also see a little bit of smoke from the breather.

I had to take the engine apart.

The pistons are damaged, and so is the block. I put the block into the trunk of the daily driver and asked around among professionals and the verdict is that three pistons are gone, the block can be saved but it would be easier and cheaper to simply buy a new one. Fortunately the head and the rods are not damaged at all.

Damaged block and #3 piston

Damaged piston

I found a good document about piston damage.

Except that, all bearings and everything else looks as new.

The people I've asked about the engine agrees with my theory of what happened - the alternator stopped charging, and when the battery discharged during the day the fuel pump could not keep up on the long Mantorp straight and the engine run lean.

Front cover oil leak

Since I rebuilt the engine I've had an small oil leak somewhere around the front cover. It has not been any problems at all with normal street usage, but after a track day the the leaked oil makes a mess from the front cover and rearwards.

I had my dampers dismounted for another reason and now I had plenty of space in front of the engine. I removed the starter motor to be able to lock the flywheel with a chisel when removing and tightening the front pulley bolt.

I used CRC Gasket Remover to  remove the old sealant a bit easier.


New pulley bolt, new front mainshaft seal, new diamond washer, new bead of RTV sealant.

Because the front pulley was removed I had to set the cam timing again. Easy when you've done it before.

Dry sump blanking cap

New vs old

On the EU4 CSR 200 there is a hose between the external dry sump oil tank and the dry sump. When I rebuilt my engine I changed to an open oil system, and that hose was no longer needed and the unused hole in the sump needed to be blanked.

The problem is that it uses a very unconventional thread: MF22x2.0

After many failed attempts to find a fitting blanking cap I finally went directly to the source - Titan Motorsport, and of course they had one.

So for the record, the part number is:  A1016510200A3


For both theirs and my convenience I ordered it from Burton, who in turn got it from Titan.

Fuel injector voltage compensation

I've noticed that the engine sound changes when the cooling fan kicks in. Not a big deal, I thought, but now I understand it is something worth a bit of attention.

Injector "dead time" is the time between pulse and fuel is delivered. What makes it a little bit complicated is that the dead time is not only voltage dependent but also fuel pressure dependent.

When the fan kicks in, or the headlights are lit, the battery voltage is dropped. The ECU have a voltage compensation map that add some time to the fuel map. If that map isn't correct the engine rpm may drop, causing the alternator to generate less current, even less fuel, and the engine could eventually stall. If we use closed loop lambda control the ECU would stable the engine within a second, but what would be written to the long term fuel map?

In my case the compensation map set up was not correct for my injectors.

The easiest way to measure injector dead time is to have the engine running and measure the lambda. Then remove the alternator control cable to drop the voltage about 2v, and see if the lambda changes. Adjust the map until the lambda reading is as before the alternator was disabled.

A more accurate way is to start the engine, remove the battery and connect a variable voltage source, and then disable the alternator and measure lambda at different voltage levels and adjust the map accordingly.

Or, you could do as I did and Google the injector's specs.

Bosch "Green giant" injectors at 4 bar, MBE 9A4:

It worked.

Wideband lambda

I've installed an Innovate LC-1 wideband Lambda controller connected to my MBE 9A4 ECU.

A wideband lambda output a linear 0-5V AFR (air/fuel ratio) sensor reading for a wide range of lambda values, in contrast to an ordinary lambda sensor that output more like a narrow rich/lean reading compared to a fixed reference. This makes it possible for the ECU to real time control the fuel mixture to a set value, based on the these readings - "closed loop lambda control".

The 9A4 also supports a long term AFR adjustment map, a bit like "self mapping". Some of the difference between the expected and measured lambda value is written to the long term adjustment fuel map, so the next time it is time fire the injectors for the same conditions it uses the updated value. For making the changes persistent to the primary fuel map you manually have to select to merge the long term map into the primary map with a computer connected to the ECU. The long term map is cleared after ECU power loss.

This sounds a bit too good to be true, and probably is. I've done some internet forum digging and it seems like it is not recommended to use closed loop lambda control when the engine is under high load, although the reasons why are a bit vague. For medium load and idle it seems to be no reasons not to use it. And for logging ECU data a wideband lambda sensor is a great tool.

However it won't work unless you have a pretty good base map to begin with.

The wiring was a bit fiddly and time consuming but pretty straight forward.

It took some trial and error to figure out how to program the ECU, so I thought I'd do the world a favour by showing my setup for the LC-1 controller configured with factory defaults. (Analogue 2 output from the controller into the ECU, brown wire).

Start with the "Analog Lambda Sensor 16 bit Index Map" setting. This tells the ECU the sensor input is linear and the interesting voltage range is between 0 and 5V.

Then "Analog Lambda Sensor Calibration" setting. This is what voltage corresponds to what lambda value. This is for the factory settings, 0V = lambda 0.5 and 5V = lambda 1.523.

Set the Oxygen Sensor lower and upper limits settings to 0 and 5V.

And finally you must have a target lambda map. Target lambda 1.0 at idle, and lower (richer) for more power at load.

Target lambda map. NOTE! The values used here are quite lean!!

Start the engine, and if all readings seems fine you can activate lambda control by setting "Lambda A (1) Control Enable".

After about 30 seconds from engine start, the ECU should start to adjust the engine's AFR to follow the current target lambda.

Air temp sender location

The Cosworth carbon air box is supplied with a combined MAP and air temp sender, which measures temp and pressure inside the air box. After studying an ECU log file it reveals its location for air temperature is far for optimal. 

Blue line is air temp. The real temperature this
evening was around 11 deg C, not 29. 

I have now moved the sender to in front of the left footwell. The MAP sensor I only use as a barometer sensor before starting the engine so it will do its job just as good outside of the air box.

Old sensor location

Engine upgrade - part #9 - final results

So far the engine have behaved extremely well and almost no problems at all. A bad battery connector, small coolant leak because of a loose jubilee clip, oil filler cap leak, but nothing serious.

Then it was time for a rolling road session at Turbocenter. It was kind of the ultimate test to see if the build was successful or if the engine would dissolve in a puff of smoke. The first time Claus took it to rev limiter my hands were shaking and my heart was up my mouth, but it held together!

As you can see in the video, in the beginning there was some problems with tyre slip against the rollers. I left the car with them for a week while going for a well needed vacation and I'm not sure how he solved the tire slip, but I think he tied down the roll cage to the floor. 

The final result is: 231 hp on the rear wheels @7500 rpm. Max torque ~230Nm. It would for sure be interesting to know how much that power would equal on the flywheel, but that is impossible to find out. Google it and you'll find lots of opinions on this subject. The loss is dependant on gearing, tyre wear, tyre air pressure, moon phase etc etc and even compare the same car on the same dyno two different days could generate different results. But I guess crank power around 270-280 hp is within reason.

As seen on the chart I have a problem maintaining constant fuel pressure when power increases. The reason for this could be many, leaking low quality fuel regulator, insufficient fuel pump, clogged fuel filter, too narrow fuel lines. Before buying a new pump Claus recommended me to move the fuel regulator to the end of the fuel rail, and put the fuel return line from there. He had a neat solution for this and I might give that a go further on.

I also have a power plateau around 4500 rpm. I don't know why. Could it be the exhaust system? I leave it as it is for a while and let all this digest until I feel ready to handle it.

Immediately when I got the car I took it on a test drive. It is early April and the roads are cold and my tyres have almost no rubber at all, but on all of the first four gears I got wheel spin when getting into the engine's power band!! This is crazy!

UPDATE: A test run this morning. Here is a 110-190 km/h comparison before and after:

Special thanks to:

Hanns Per Kober
Jeremy at Cosworth
Steve at SBD Motorsport
Claus at Turbocenter
Jan at ENEM

Also thanks to:
Kenneth at Motortjänst
Nacka Biltrim
Helpful members at Focaljet


All parts:
Engine upgrade part #1 - intro
Engine upgrade part #2 - disassemble
Engine upgrade part #3 - parts
Engine upgrade part #4 - block assembly
Engine upgrade part #5 - head
Engine upgrade part #6 - putting it together
Engine upgrade part #7 - electrical and fuel
Engine upgrade part #8 - first start
Engine upgrade part #9 - final results

Engine upgrade - part #8 - first start!!!

Finally it was time for the first start of the engine. The whole family was excited and my wife would help me with operating the throttle pedal, and my kids have promised not to destroy anything and keep out of the way.

• I primed the oil system by cranking the engine without plugs. I expected a oil pressure reading on the gauge but nothing happened. I plugged a volt meter directly to the sender connector, and after a few revolutions I got a reading on the meter, so the reason I didn't see anything before was simply something with the wiring to the oil pressure gauge. Update: It was simply the oil gauge connector on the backside of the dashboard that had fell out.
• Fuel in the tank and connected the fuel pump power. A few on/off with the ignition primed the fuel system.
• Computer connected to ECU, extra starter battery, voltmeter connected, wife in drivers seat, kids out of the way, cameras on and... NOTHING! The starter didn't have enough power to turn the engine! Talk about anti climax!
• Borrowing a starter battery from the daily driver and exchanging the small lightweight racing battery with a more powerful kind.
• Another attempt was made and it started after just a few revolutions!

Next part - Engine upgrade part #9 - final results

All parts:

Engine upgrade part #1 - intro

Engine upgrade part #2 - disassemble

Engine upgrade part #3 - parts

Engine upgrade part #4 - block assembly

Engine upgrade part #5 - head

Engine upgrade part #6 - putting it together

Engine upgrade part #7 - electrical and fuel

Engine upgrade part #8 - first start

Engine upgrade part #9 - final results

Engine upgrade - part #7 - electrical and fuel

My old Ford BlackOak ECU is locked so I needed a new after market ECU. My choice was MBE 9A4, because it already was proved to be working good with Duratecs, but mostly because that was the ECU my local engine builder workshop knew best and also sold parts for.

Duratec loom

As I wrote in a previous post I ordered the ECU and a Duratec loom from SB Motorsport. The loom was missing some 'features' that existed in my previous loom, so quite a lot of wiring was needed. Most if the wireing was made while the engine was in out of the car while waiting for parts. I took the original loom apart and reused the connectors, and removed the wires that was no longer needed. Two relays where already in the new loom, but I needed two more relays for starter solenoid and cooling fans.

• Fan switch relay, controlled by the ECU.
• Starter solenoid coil relay, from ignition key.
• Ignition to ECU, from ignition key.
• Coolant temp, oil pressure, rpm (from ECU), to the dash.
• The lambda sensor connector was of the wrong type.
• Throttle position sensor connector changed, and the TPS was calibrated.
• The air box from Cosworth came with a Bosch MAP sensor with integrated air temperature sensor. It is not necessary with a MAP sensor with roller barrels, but I decided to use it anyway because that way I didn't need a barometer sensor. A few more electric wires from the ECU was needed, and calibration of both temp and MAP sensor. The temp sensor was calibrated using a fridge and an oven. The map sensor is linear so it was easy to calibrate once I figured out the sensor high and low spec values.
• A new coolant sensor was fitted to the coolant elbow in the rear of the engine. I had to manufacture an adapter from a 3/8" NPT to M12x1.5 using pipe parts from the local hardware store.

• The fuel pump controller module which exists on the EU4 model was removed, and a new adjustable fuel regulator was fitted.

• I did a rough adjustment of the fuel regulator using an electric tyre air pump with manometer. Cosworth recommends 4.3 bar for their 280 crate engine.

Next part: Engine upgrade part #8 - First start


All parts:
Engine upgrade part #1 - intro
Engine upgrade part #2 - disassemble
Engine upgrade part #3 - parts
Engine upgrade part #4 - block assembly
Engine upgrade part #5 - head
Engine upgrade part #6 - putting it together
Engine upgrade part #7 - electrical and fuel
Engine upgrade part #8 - first start
Engine upgrade part #9 - final results

Engine upgrade - part #6 - putting it together

• Head and block now back together with new ARP bolts and new gasket. 60 lb/ft in three stages and ARP lube. A dab of sealant on marked spots in the assembly guide.
• Chain guides and cam chain.
• Alternator

• Roller barrels
• New fuel rail and injectors (310 g/min)
• I put the engine on the floor and mounted the flywheel with new OEM bolts. The flywheel could be easily locked using a chisel on the starter ring, holding it against the block.
• The old clutch. I already had the type of clutch used on CSR 260. I used an extended socket I normally use for the spark plugs as centring tool.

• Coolant hoses and coolant rail. I made a simple coolant temp sensor adaptor (M12*1.5 to 3/8" NPT). Or actually, I let the engine builder thread the inner hole because I didn't have the right tap.
• The old hose from the oil tank to sump was plugged using a standard brass 1/2" NPT plug from the hardware store. Here I can save a few grams by changing to an aluminium plug :-)
• Cam chain and camshaft sprockets with new bolts and new friction washers.
• Front cover with sealant

Finding true TDC

• Front pulley. New bolt and new friction washer. First I put cylinder 1 on true TDC, using a dial indicator and pencil. I locked the pulley with a small bolt through the locking hole. A helper hold the flywheel using the rear part of an hammer against the starter ring and a bolt in one of the bell housing holes. With a big breaker bar I could turn the bolt the last 90 degrees. Not easy, but it worked. The cams were not locked during the tightening of the front pulley.

Locked cams

• Then it was time for cam timing. The cams where locked using the timing bar grooves and cylinder 1 was put at true TDC again, and the cam bolts where tighten. The timing was then measured with a dial indicator by turning the engine and with a degree wheel find when the intake and exhaust valves are fully open. To my surprise the timing was spot on and no adjustments were necessary.
• Cam cover
• Belt, belt tensioner
• Starter motor (35 Nm)
• Bellhousing and gearbox (47 Nm)
• Airbox and filter, using thread lock! I don't want any of those screws sucked into the engine.

And... the engine is finished! Time to put it back into the car.

Shoe horning the engine into the car is really frustrating. After some cursing I removed the oil cooler/filter holder and starter motor. Much easier, but maybe not that easy to put them back on.

The brake master cylinder fooled the new air box, so I had to remove some carbon from the air box.

Next part: Engine upgrade part #7 - Electrical and fuel


All parts:
Engine upgrade part #1 - intro
Engine upgrade part #2 - disassemble
Engine upgrade part #3 - parts
Engine upgrade part #4 - block assembly
Engine upgrade part #5 - head
Engine upgrade part #6 - putting it together
Engine upgrade part #7 - electrical and fuel
Engine upgrade part #8 - first start
Engine upgrade part #9 - final results

Engine upgrade - part #5 - head

The head is back, ported nice and smooth, valve seats refurnished and the old valves grinded.

Refurnished valve seats

Smooth inlet

• Fitted new valve seals. Just press them in place with a socket large enough.
• Installed the valves with uprated Cosworth springs

Valves, springs, retainers and cotters

• Put back the old cam followers and installed the new camshafts. 
• Measured cam to valve clearances "lash" with feeler gauges. According to Cosworth the clearance should be inlet 0.22 – 0.28mm and exhaust 0.27 – 0.30mm for my cams. They were all off since the refurnished valve seats made the valves to sink deeper into the the valve seats. To be sure I moved around the old buckets and remeasured several times, but the readings were not that consistent, and some clearances was too small for even the smallest feeler gauge. 
• Eventually I had a complete list of the sizes I needed with 13 new buckets. A few of the sizes was more or less guesses, so I was prepared to order a couple more later on.  Finding a retailer with the buckets in stock was not easy, but to the rescue was SBD Motorsport who had them shipped within a couple of days. Cosworth also had them in stock, but to quote someone well known in the business - "nothing is fast from Cosworth other than their engines". 
• Meanwhile I fitted the head back to the block with new ARP studs and a new gasket. No problems but I was really close to drop a washer into an oil gallery.. Phew..
• Doh! Measuring lash before attaching the head to the block was a bad idea. Some of the measurements have changed (and some was more or less guesses to begin with). A new order to SBD, luckily the delivery was only a couple of days.

Finding TDC using a pencil and a dial indicator

• Buckets in place and lash within spec
• Camshafts in place with lots of assembly lube.

Next part: Engine upgrade part #6 - Putting it together


All parts:
Engine upgrade part #1 - intro
Engine upgrade part #2 - disassemble
Engine upgrade part #3 - parts
Engine upgrade part #4 - block assembly
Engine upgrade part #5 - head
Engine upgrade part #6 - putting it together
Engine upgrade part #7 - electrical and fuel
Engine upgrade part #8 - first start
Engine upgrade part #9 - final results

Engine upgrade - part #4 - block assembly

The block is back from the workshop, clean as a silver plate, and finally I could start to assemble the engine. Torques are taken from the Ford Duratec assembly manual unless other sources are mentioned.

ARP studs and main bearings

´

• Main bearings, greased with assembly lube
• Crankshaft
• ARP main bolts (60 lb/ft in = 89 Nm in three equal steps with ARP lube. Source: ARP)
• Rear oil seal (9.8 Nm)

Cover plate

• Crank oil breather cover plate (9.8 Nm with Loctite 5910 sealant)

Measuring ring gap. The cylinders are honed by the shop.

• Checking piston ring gap using feeler gauges. Upper compression rings needed some adjustment - I gapped them so the 0.40mm feeler just could get between with some resistance. (upper 0.25-0.51mm, lower 0.50-0.63mm. Source: Cosworth)

Carrillo recommends the following method for tighten con-rod bolts: "In order to check bolt stretch, simply fixture one rod, leaving the cap portion free from clamping load. Measure both bolt lengths loose, then progressively tighten the bolt until the measured increase in length correlates with the figures below. Use the indicated torque reading to tighten all the connecting rods in final assembly." Specified stretch is 0.130-0.160mm, max 54 Nm. Source: Carrillo.

Very simple home made bolt stretch gauge

Well, even if my stretch gauge was a bit primitive I was pretty sure I didn't reach the min-stretch value using 54 Nm of torque, even if I tighted them serveral times. After consulting Carrillo I got the response "The 40 ft lbs (=54 Nm) is the number we use to make sure that people who do not check stretch do not over torque the fasteners. If you have to go above the 40 ft lbs this is ok to do to reach the proper stretch."

I used the anti-seize lube supplied with the rods.

Pistons in place, from below

Pistons in place, from above

Then some trouble...

When I was about to mount the dry sump, it got apparent that something was wrong. The new ARP studs where a bit too long, and interfering with the bolts fasting the sump's windage plates.

The sump with windage plate and its black bolts. 

ARP stud against bolt

OEM bolt compared to ARP 

Cosworth say they use OEM bolt on their 280 crate engines, but in their catalogue they have the option to upgrade to ARP bolts. When looking at pictures on the dry sump, they looks a bit different than mine so I maybe I have an early version of the sump?

Some people I asked said the OEM main bolts could be reused. Other said never, ever, reuse TTY bolts. One or two of my old OEM bolts looked a bit stretched, and was a few tenths of mm longer than the others so I didn't dare reusing it.

I consulted ARP technical support who said that it was ok to remove some material from the studs if they're too long. They also said never to mix different materials, the washer included.

So it took the studs out from the engine again, and cut about 3 mm with a angle grinder. Much easier than I thought it would be, they cut right off. Unfortunately that was not enough as I also had to grind the windage plate bolts in the sump making their profile a bit lower. (and harder to remove in the future).

And finally I could mount the dry sump. I used Loctite 5910 sealant.

• Oil pump chain + spockets + tensioner. New uprated friction washers on the main shaft sprocket.
• Water pump + thermostat
• Oil cooler and filter holder

Next part: Engine upgrade part #5 - Head


All parts:
Engine upgrade part #1 - intro
Engine upgrade part #2 - disassemble
Engine upgrade part #3 - parts
Engine upgrade part #4 - block assembly
Engine upgrade part #5 - head
Engine upgrade part #6 - putting it together
Engine upgrade part #7 - electrical and fuel
Engine upgrade part #8 - first start
Engine upgrade part #9 - final results