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MaxDiesel

Time for a top end rebuild ?

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So far so good.... 90 miles of the run-in done and still no leaks or strange noises :) Engine seems very smooth and pulls well from low revs.

 

Had a slight concern over the amount of air bubbles in the oil, fortunately had a second oil filter - fitted this and much better now. Think I'll go with Knecht/Mahle filters in the future rather then Porsche.

 

Fitted one last important part today !

 

DSC00675.jpg

 

Stopped off at the Jack & Jill Windmills in Sussex this afternoon - only had my phone camera though:

 

13042009023.jpg

 

Just ordered 11 litres of Silkolene Pro S 10W-50 from Opie Oils ready for the post run-in oil change - they've got an Easter Weekend special offer with another 15% off on top of members usual discounts until midnight tonight - discount code: OPIEEGG

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Porsche filters are crap, no one should bother with them.

 

Great work mate, lovely pic of the badge :D

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Time for a run-in update:- 500 miles completed and so far so good. Runs very well and even at half throttle pulls strongly from 2000rpm :rolleyes: One minor oil leak from the oil pressure sensor block now fixed.

 

Did the 500 mile service today: all head studs and valve clearances checked - had to close a couple of the tappets up slightly, otherwise very little change from when built. Re-filled with another 10 litres of mineral oil and ready for the next 500 miles of running in.... :steering:

 

Aiming to get the next 500 done within the next 2-3 weeks and then get back on the dyno to compare with pre-rebuild runs. Just debating whether to go fo a standard Steve Wong chip or the custom chip option....

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Nearly there now: 900 miles of the run-in complete and still going well. Started to push it a bit harder now - been up to 6000rpm and feels good. Going to use the next 100 miles or so to push on to full load and rpm, then check tappets & heads studs and fill with some decent oil.

 

Got this today:

 

IMG_5123.jpg

 

Pretty impressive service considering I only ordered it last Thursday night ! I've gone for the stage 1 custom remap so aiming to get on the dyno in a couple of weeks and record the AFRs. Looking forward to seeing how it compares with the pre-rebuild numbers.

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Run in complete !

 

Did the 1000 miles (well 1050 miles..) post run-in service over the weekend and filled up with Silkoene Pro S 10W-50. Gave it some good hard driving for the last 150 miles on mineral oil to make sure everything was bedded in well.

 

Took the opportunity to do a leakdown check to make sure all was well inside:

 

Cylinder 1: 2% (was 16%)

Cylinder 2: 3% (was 13%)

Cylinder 3: 3% (was 9%)

Cylinder 4: 4% (was 33% !)

Cylinder 5: 10% (was 27%)

Cylinder 6: 3% (was 16%)

 

I'm pretty pleased considering they're the same pistons and cylinders as before :rolleyes: Not quite sure why cylinder 5 is higher than the others - had a listen and its definitely getting past the rings, still a big improvement over the 27% it was before though. Looked back at my measurements and cylinder 5 was the largest of the six bores with one of the lowest piston gauge diameters... so biggest running clearance. I guess this might just mean its taking a little longer to bed in fully. Will leak check again in another 500 miles to be sure.

 

Fitted the Steve Wong chip and went for a run tonight - not quite the night and day change I was hoping for but definitely more eager, especially over 4k rpm and then even more so over 6k rpm, also feels smoother at higher revs. Based on my backside dyno I reckon the increase in performance from the rebuild is more significant than the chip by a factor of 2.

Hopefully get on the dyno next week and see what its really doing - plan to refit the orginal chip to start with to see what difference the rebuild made, then fit the SW chip while I'm on the dyno and do the runs that SW needs for the custom remap.

Edited by MaxDiesel

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Run in complete !

Fitted the Steve Wong chip and went for a run tonight - not quite the night and day change I was hoping for but definitely more eager, especially over 4k rpm and then even more so over 6k rpm, also feels smoother at higher revs. Based on my backside dyno I reckon the increase in performance from the rebuild is more significant than the chip by a factor of 2.

Hopefully get on the dyno next week and see what its really doing - plan to refit the orginal chip to start with to see what difference the rebuild made, then fit the SW chip while I'm on the dyno and do the runs that SW needs for the custom remap.

 

 

:signs118: Keep it coming Max, I'm debating a chip as well, should be interesting to see the differences with yours.

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I think this is the best internet-car-engine-rebuild thread I've ever seen. Well done! Just goes to show with a bit of time/space and hands on make-a-piece-you-need talent you can just go and do it. Inspiring :signs118:

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Max did you carry out your own leakdown tests,any chance of a how to please ?

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Max did you carry out your own leakdown tests,any chance of a how to please ?

 

Yes, no problem – I did the before and after rebuild leakdown tests myself. It’s pretty straightforward to do - but my explanation may be a bit wordy !

 

I’ve been using a Snap-On twin gauge cylinder leakage tester like this:

 

post-1085-1242302341_thumb.jpg

 

Here's another one:

 

post-1085-1242302516_thumb.jpg

 

It’s basically a pair of 100psi pressure gauges with a small orifice between the two and a pressure regulator on the feed. You regulate the incoming pressure on one side of the orifice to 100psi and the second gauge measures the pressure the other side of the orifice that is connected to your cylinder. The percentage difference between the two gauge readings is your leakage – this is why its ideal to use 100psi pressure so the difference in psi = %.

 

post-1085-1242302470_thumb.jpg

 

You’re basically comparing the leakage through your cylinder with the leakage though the orifice i.e. if your cylinder has an effective leak the same size as the orifice then you have 100% leakage (not good) as the air will be exiting your cylinder at the same rate it can pass though the orifice – the second gauge will be reading zero.

 

As far as I know there's no standard size for the orifice in leakdown testers so this is why you have to be careful when comparing results between different testers as they could be operating on different ratios of orifice size versus cylinder size.

The other thing to be wary of is using the same gauge on different engine/cylinder sizes – a measured 20% leakage on a 0.5litre per cylinder engine maybe be fine, however a 20% leakage measured with the same gauge on a 0.2 litre per cylinder bike engine would mean there’s something seriously wrong !

 

I’m not sure if there's a strict procedure for doing the tests, but here’s what I do:

 

- Get your compressor set up to provide a supply pressure a good 20psi over the 100psi required for the test

- Get the engine up to normal operating temperature

- Remove all spark plugs so you can test all cylinders quickly and at similar temperature, also means you can turn the engine over easily using the alternator pulley nut

- Remove the distributor cap so you can see when you’re at No 1 TDC (when the rotor points at the notch)

- Set the engine at TDC No 1 and connect the spark plug adapter from the test kit to cylinder 1

- Set the regulated pressure to 100 psi and then connect the tester to the cylinder via the quick-connect

- If necessary re-adjust the regulated pressure back to 100psi then read off the cylinder pressure from the other gauge – the value below 100psi is your leakage amount or %

- While still pressurised you can then listen to see where your cylinder leakage is: I use a 18” long piece of ½” rubber hose for this purpose – one end place to my ear and the other to listen for leaks:

1) Place the hose end into the air intake – ideally at you inlet throttle (so after the crank breather inlet) – if you hear air escaping here then its getting past you inlet valve

2) Then place the hose in your tailpipe – if you hear air escaping here its getting past your exhaust valve

3) Then place the hose in you oil filler neck – if you hear air escaping here its getting past your rings

 

- Then continue the above process for each cylinder – making sure you rotate each cylinder to TDC first – be careful to be at TDC as accurately as you can as otherwise you rapidly crank the engine over half a turn when you connect the tester !

 

So that’s the process I use – it seems to give consistent and reliable results. I know some people use single gauge testers where you just see the pressure after the orifice – I wouldn’t recommend these as you can’t ensure you have a steady 100psi on the pre-orifice side.

 

You can do the above with a cold engine – I’ve found it doesn’t make too much difference – the main thing is that the rings are well lubricated so the engine should have run recently ideally. If you get a high leakage on a cold test I’d then check again with the engine hot before acting on it.

 

Hope the helps !

Edited by MaxDiesel

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Yes, no problem – I did the before and after rebuild leakdown tests myself. It’s pretty straightforward to do - but my explanation may be a bit wordy !

 

 

Wordy!!!! Not at all, very good write up Max. One problem i found was the pressure trying to turn the engine, how do you stop that happening.

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One problem i found was the pressure trying to turn the engine, how do you stop that happening.

I must admit I didn't find this was a problem providing I got the engine set right at TDC i.e. within +/- 1mm on the the timing mark.

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So moment of truth time - put my car on the dyno this evening to see how its performing post rebuild. Still only 1100 miles since the rebuild so may still have some bedding in and loosening up to go. Haven't managed to process the data from the runs yet but I eyeballed the max power values during the runs.

 

I started with four power curves using the original chip then fitted the SW chip and did another four runs. Also did the neutral speed sweep AFRs and a couple of 75% pedal runs as requested by Steve for the custom remap. So results are:

 

Pre-rebuild: 215 hp

 

Post rebuild with stock chip: 234 hp

 

Post rebuild with S/W chip: 244 hp

 

All the above are flwheel hp assuming 15% drivetrain losses. The numbers pretty much confirm my gut feel that the benefit from the rebuild was 2x the benefit from the chip. Also tests were run with ~5 metre long 80mm diameter exhaust hose leading out the dyno as its in a sealed building - can't imagine this helps the power numbers too much !

 

The lambda values looked a little erratic at the top end with the S/W chip so there may be a bit more to come when its custom remapped - will go back on the dyno and check once I've got the updated chip - would be nice to hit the magic 150hp !

 

I'm pretty pleased with the numbers - gettting the engine back to the stock power levels was the main aim of the rebuild, the SW chip is giving a nice bonus on top. Will post some charts later this week - I'm expecting the SW chip to show an improvement in peak torque and wider power band also.

Edited by MaxDiesel

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Max,

though I haven't done leak downs for some time (donkeys), did you carry out the check with the piston at TDC on all cylinders?

 

Why I ask is, IIRC we used to carry out the check at three positions per cylinder, TDC, mid stroke then BDC. The reason I seem to remember is that at TDC the 'coke ring' can affect the readings - generally on the positive side - mid stroke (fastest piston speed area) generally showed higher (or truer pressure 'leakage') readings.

I may well have dreamed it :rolleyes: but I am sure this is how we carried this out. What highlighted this to me was Coxy's question about kicking the engine over, we used to put in gear and roll it to mid stroke - watched via the timing marks.

 

Does this make sence?

Regards

 

Jammo. ;)

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Max,

though I haven't done leak downs for some time (donkeys), did you carry out the check with the piston at TDC on all cylinders?

 

Why I ask is, IIRC we used to carry out the check at three positions per cylinder, TDC, mid stroke then BDC. The reason I seem to remember is that at TDC the 'coke ring' can affect the readings - generally on the positive side - mid stroke (fastest piston speed area) generally showed higher (or truer pressure 'leakage') readings.

I may well have dreamed it :rolleyes: but I am sure this is how we carried this out. What highlighted this to me was Coxy's question about kicking the engine over, we used to put in gear and roll it to mid stroke - watched via the timing marks.

 

Does this make sence?

Regards

 

Jammo. ;)

 

Interesting - I've always done them at TDC and I think this is the most common way to test. Its a fair point though whether the ring seating at TDC is representative of other parts of the stroke - you can get some interesting wear marks at the point of top ring reversal which may or may not have an impact on the results. When I do the next check I'll try a couple of readings mid stroke and see how they compare with the TDC numbers

 

Cheers

 

Matt.

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Sorry Matt, forgot to mention, excellent write up though, as Coxy stated - cracking.

Regards

 

Jammo. ;)

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Just compiled the final list of parts I replaced during my engine rebuild - thought this might prove a useful checklist for anyone embarking on a similar rebuild:

 

finalengineparts.jpg

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Hi Max,

cracking list there - I suppose it would be a tad 'imposing' :blush: but what was the price list to go along with the parts list? Been a while since I had lists like that to contend with.

Regards

 

Jammo. ;)

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cracking list there - I suppose it would be a tad 'imposing' :blush: but what was the price list to go along with the parts list? Been a while since I had lists like that to contend with.

Hi Jammo - yes there's a price column also..... I've been trying to avoid looking at the total too often though !

Total for everything on the list shown was ~£2.3k - I got some good deals to acheive this - prefer not to show these individually though.

Hope this helps,

Matt.

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Had a chance to process the data from my dyno runs last week and compare it with the pre-rebuild runs:

 

powercurvecompplot.jpg

 

Final numbers are -

 

Pre-rebuild:

Peak torque of 200 lbs ft @ ~5000 rpm

Peak power of 214 hp @ ~5850 rpm

 

Post rebuild with standard chip:

Peak torque of 214 lbs ft @ ~5000 rpm

Peak power of 235 hp @ ~6150 rpm

 

Post rebuild with initial SW chip:

Peak torque of 217 lbs ft @ ~5200 rpm

Peak power of 244 hp @ ~6200 rpm

 

I've sent all the data to Steve Wong and he reckons there's still some to come from the custom remap - its running leaner than optimum over 5500rpm so he's going to increase the fuelling through the to the red line and also add a little more advance. Here's a comparison of the Lambda with the standard chip versus the intial SW chip (four runs for each):

 

Lambdacomparison.jpg

 

I'll run it on the dyno again as soon as I get the revised chip.

Edited by MaxDiesel

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Total for everything on the list shown was ~£2.3k - I got some good deals to acheive this - prefer not to show these individually though.

Good work mate.

 

Worth pointing out to anyone picking this thread up in a few months/years that Matt did a full rebuild. The thread title says top end but the engine was totally rebuilt.

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One of the threads I missed whilst away. Amazing write up :ani_clapping:

 

Top work definately a contender for best thread ever. Almost encouraged me to get on with my car..........steady.

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Thought it was about time for another post run-in update:

 

2200miles now completed and all going well still. Checked the oil yesterday and it hasn't used any since I refilled it at 1050miles - quite an improvement from the near litre per 1000miles it was before :rolleyes:

 

Also had a chance to look at the data from my custom Steve Wong remap based on the dyno data from the first chip:

 

Power was almost exactly the same as with the first SW chip - had been hoping for at least a couple more !

 

powercurvecompplot2.jpg

 

Lambda is now pretty much optimum at ~0.89 up the power curve:

 

Lambdacomparison2.jpg

 

Sending the data to SW to see if he thinks there's any more to come.

 

Still working on my HFM5 hot wire MAF conversion - hoping to have this ready to test in a couple of months time....

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Did another leakdown check on my engine yesterday - now 3200miles since the rebuild. Main purpose was to rule out any possible engine causes for the high speed misfire I'm trying to fix but its also interesting to see how the cylinders have bedded in over 3000miles:

 

leakdowntests-1.jpg

 

Still not sure why cylinder 5 is higher than the others - I moved the piston down to mid stroke and locked the engine (idea from Jammo I seem to recall), re-did the test and got ~1% so looks like it's just some slight wear at TDC or just taking longer to bed in.

 

I'm pretty pleased with these numbers considering they're the orginal pistons and cylinders (Nikasil) - shows its worth hanging onto you're original Nikasil cylinders even if they've done 100k plus miles.

Edited by MaxDiesel

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Hallo,

 

I found the thread at this time. Great job. :ani_clapping:

I´m at the same job in this time !

 

Hope I will get the same good performance. :unsure:

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