[engine_work] Xu9j4 Mi-16 Rebuild

[petert 586]

If you take a big skim off the block, like 1.4mm, then you need to add offset keys as there isn't enough pickup on the intake tensioner to take up the belt slack. Most of the tensioning is done by the exhaust side, which retards the cam timing. I doubt you've taken that much off if the engine was a D6C. Possibly 0.4mm? The #4 pulley will correct that and I expect you'll be close to 0.065".

 

You can see on the dyno runs where I tried to take out excess fuel at approx 6000rpm. I didn't take out enough so it still dips to 12:1. For the most part, it's 12.5 to 13:1 however. Attached is the WOT fuel map for your chip. The ignition map is not that one. That's std. 158/161.

Edited January 25, 2012 by petert

[kyepan 291]

evening,

 

So, two things, Cam timing was a little out, and the fuel pressure regulator was only holding 2.5bar under load. As predicted by both Sandy and Maxi, it made exactly the same peak power. Driving wise in transitional type situations and light / medium throttle applications at low / medium revs it just goes so much better. Also it doesn't sound hollow any more.

 

 

We also tried a couple of AFMs, one had been tinkered with, and ran it very lean, very very lean, you could hear it was lean, even leaner than with my dodgy FPR, we binned that idea, then the second ran it much richer, again it made no more power, about 5 bhp less.

 

The most interesting developments are around the cam timing. Anthony noticed that the bottom pulley was advanced a bit, meaning the other two were advanced when the whole thing goes round. This needed addressing.

 

When it was originally set by paul and I after the lifter problems, we must have got it spot on, because you can see on the graph it pulls to the redline, I'm fairly sure we used lots of rear tensioner, and then just enough front to tension the belt, and the bottom pulley dead centre. Also Peter, the chip seems to be topping out at 7200, which is odd as i thought the rev limit was 7500.

 

 

Just to clarify, the kinds of silly differences in pulley position were talking about are 2-3 mm of wobble on the 6mm alan key we used in the bottom pulley, and even wobble in both directions.

 

So this time we got the pulley bang on, then took a bit of rear off, and put a bit of front on. The difference was interesting. Yes it was still advanced of the original setting, but not as much as last week.

 

We did a couple more runs on the new setting, and whilst it did drop off at the very top again because it was a bit advanced as before, it gained noticeable amounts at the first peak at 3k and the second trough from the intermediate setting was gone again.

 

I can see why people time cams using dial gauges, and proper TDC markings, doing it any other way is pure guesswork. and can make a noticeable difference to your power delivery.

 

170bhp, on standard inlet / exhaust, 700 odd miles so far, and it's loosened up nicely.

 

Job done.

 

Cheers

 

J

Edited January 27, 2012 by kyepan

[Paul_13 212 1 Cars]

 

[Anthony 1,003]

"Justin hopes that giving his steed some soft words and sweet lovin' will increase the power figures"

[kyepan 291]

 

 

 

"Justin hopes that giving his steed some soft words and sweet lovin' will increase the power figures"

 

GUYS!!! that was a Private Moment!!!!

[maxi 36 1 Cars]

Cam timing is EVERYTHING on these original Mi's.

 

I still believe the best setup for a std 1905mi is 3 row management, shortened inlet, AMC TB, std exhaust manifold mated to a bosal exhaust without the split. A tight belt with the pin holes correctly aligned and this WILL see 170BHP if the engine is healthy.

 

The expert/engine scientists on here will poo poo my statement but it works. Ive done it, lots of times.

 

I think you have good power from your car but I would try to give you one word of advice, dont try to make it something that it isnt. You have a good strong brand new engine, its making good power for a 1.9, enjoy it and look after it. That car will give you years and years of fun but - and I have seen this many times before on the forum - dont try to chase something that isnt there. Lots of fiddling and tweaking and swapping, tensioning and re-tensioning, to try to find 1-5BHP is going to end up ruining your masterpiece and this really is a masterpiece/personal achievement for you.

 

Give yourself a pat on the back, a full tank of juice and thrash the arse out of it.

 

Maxi

[maxi 36 1 Cars]

A perfect example, do you remember Chris White (?) and his BX? He lived about half hour from you, just inside the M25 (I bought a BX from him around 7-8 years ago). He was mad about his BX, (D6C) after a lot of money and effort he did a TB conversion and cams on his car. It also had fast road piper cams (from memory, might have been kent). He never broke the 175BHP - 180BHP barrier. It drove him crazy, he tweaked, adjusted and threw more and more money at it. In the end, im sure it wrecked his love for the car and it was shortly sold. This always stuck in mind. Two conclusions I drew from this that ALWAYS stayed with me:

 

1. Peugeot made a cracking magical job of the D6C. It is happy and magical at around the 160 -170BHP mark, it will never be more than this, because no matter what the engine scientists say this is its natural happy area.

 

2. Chasing something that isnt there can ruin your own earth moving achievements. He loved that car and through fiddling, he ruined it.

 

I hope this hasnt offended you, I have the upmost respect for what you have done here and you have a cracking result, just enjoy it.

 

If I could turn back time I always would have stuck with std mi16s. Magic.

 

Maxi

[wicked 103 3 Cars]

3. Don't disappoint your engine by putting it in a BX... It will work harder if you put it in a nice car.... :lol:

[kyepan 291]

i'm really touched maxi, thanks, i mean that.

[petert 586]

I think I've got my head around this. The camshaft is ground 1 degree advanced. I do this so it works perfectly with a #3 pulley. This equates to 0.065" @ TDC. The #3 normally gives a 111º lobe centre line with a standard cam. Thus the cam you have would be theoretically at 110º with a #3. A #4 pulley has a 107º LCL. Thus your cam would be at approx. 106º, which is probably advanced too far, giving a lift @ TDC figure >0.065". This is good for low-mid range torque but hurts top end power. If you have a spare #2 around, fit that for a comparison. As you're an expert at changing cam belts now, you'll be able to do that in 15 mins!

[matyasg 0]

3. Don't disappoint your engine by putting it in a BX... It will work harder if you put it in a nice car.... :lol:

Nothing wrong with a BX ..

[matyasg 0]

I was thinking about asking if anyone had an AFR trace with your chip peter, so thanks for the great reply! Hopefully i'll get a chance to look at it on thursday.

 

I'm running #4 inlet and #2 exhaust, and have had the block refaced a bit, but i wouldn't say any significant amount removed desk height wise.

I don't have a trace, but my LC-1 says 12.5:1-12.7:1 on WOT with petert's chip. I use #3 inlet and #2 exhaust pulley.

 

I had a lot of mess with setting up the AFM, at the end I plugged out the narrowband signal to the ECU and checked AFR on the wideband. I rotated the AFM to that position where the wideband said 14.7:1 on idle (with warm engine). result: very smooth idle and good part throttle response.

 

I've never been on a dyno with this, so I can't show you any grapsh or tell power figures.

[kyepan 291]

I think I've got my head around this. The camshaft is ground 1 degree advanced. I do this so it works perfectly with a #3 pulley. This equates to 0.065" @ TDC. The #3 normally gives a 111º lobe centre line with a standard cam. Thus the cam you have would be theoretically at 110º with a #3. A #4 pulley has a 107º LCL. Thus your cam would be at approx. 106º, which is probably advanced too far, giving a lift @ TDC figure >0.065". This is good for low-mid range torque but hurts top end power. If you have a spare #2 around, fit that for a comparison. As you're an expert at changing cam belts now, you'll be able to do that in 15 mins!

 

 

I have three unused #2 pulleys... and a job for the weekend.

[kyepan 291]

It drove him crazy, he tweaked, adjusted and threw more and more money at it. In the end, im sure it wrecked his love for the car and it was shortly sold.

I've been thinking about this quite a bit over the past week or so.

 

 

 

In the first run it was fitted with an offset key on the inlet camshaft to advance the inlet timing 4 degrees. This effectively takes the inlet lobe centre line from 111 deg. ATDC to 107 deg. ATDC. Many achieve the same by fitting vernier pulleys. This change makes the engine a lot stronger in the mid range , moving top end horsepower peak down a tad. With this modification the car is a joy to drive at 100-110km/h. It will overtake with ease in 5th gear.

So that must be a #3 pulley with the key

 

 

so getting near 107 given by the woodruff key with a pulley would be possible based on the

this post written about five years ago states a #4 is 108.. which is near enough for me.

 

The offset key is a simple solution to finding torque. Some people like to spend hundreds on vernier pulleys, when all they need to is change the key and/or fit a different pulley. There's no point in moving (or changing) the exhaust cam on engines up to 200hp, so fitting a vernier here is a waste of money. There are three different inlet pulleys, which were fitted to different variations of the XU9J4. The inlet lobe centre lines go like this:

 

#2 - 114 deg.

#3 - 111 deg.

#4 - 108 deg.

 

Moving the inlet cam to 109 - 106 deg. gives a much broader and useable power range. Fitting a 4 deg. offset key with a #3 pulley gives 107 deg.

 

But then looking at your site...

 

The #3 pulley is used on the XU9J4Z inlet cam to advance the cam timing 3 degrees (crank). This keeps the dynamic compression of the lower compression engine higher, increasing torque and drive-ability. Later XU9J4 engines were fitted with #4 pulley on the inlet. This advances the inlet cam by a further 5 degrees to a 106 degree centreline.

 

XU9J4 LATE

 

Inlet Lobe Centre

106

 

Inlet Lift @ TDC (in.) 0.054

 

Inlet Cam Pulley #4

 

 

Here's where the confusion comes from, the website states 106, original post states 108 that i took as gospel, this post states 107.

 

so fitting a #4 pulley and a stage 1 cam actually gives 105 deg, not the 108 i originally hoped for.

 

 

A #4 pulley has a 107º LCL. Thus your cam would be at approx. 106º, which is probably advanced too far, giving a lift @ TDC figure >0.065".

 

 

I hope this post doesn't come over as either a whinge or a dig, because it's neither. I just want to clear my mind of this cam timing issue, and make a decision about whether i stick with what i have now, knowing it's too far advanced - or revert to a #2 pulley and a standard ish MI power band.

 

cheers

J

Edited February 9, 2012 by kyepan

[welshpug 1,657]

or just get a pair of adjustables and play with it to your hearts content

[petert 586]

Better still, measure lift @ TDC with a dial indicator.

 

I must admit that is confusing! It was a long time ago when I measured the #4. I'd go with what I said on the website. Either way, you can see from the dyno plot it's too far advanced.

[DrSarty 90 1 Cars]

Well done Justin.

 

I spoke with Anthony today, and will shortly be proposing a retro-style, south curry meet for old times' sake where perhaps you can take me for a spin in your freshened-up motor.

[petert 586]

DrWho? Now there's a name I haven't seen on here for a long time. How are you Richard?

[kyepan 291]

Well done Justin.

 

I spoke with Anthony today, and will shortly be proposing a retro-style, south curry meet for old times' sake where perhaps you can take me for a spin in your freshened-up motor.

 

Thanks, it's been an involved and satisfying journey. Speaking of which, where the bloody hell have you been!

 

Car will be ready for passenger rides in a month or so, just finishing off a few minor details....

 

Suggest we do Alesbury again as that was nice and easy for a big group to get to!

 

ps you have a dirty load of warn on your gauge, naughty richard.

Edited February 16, 2012 by kyepan

[DrSarty 90 1 Cars]

I like warn; warn is for winners.

 

Hi Pete.

 

The story's long, but so's my Johnson.

[kyepan 291]

Less of the long cock talk on my thread Dicky boy. Stick that in natashas soft topics..

[kyepan 291]

A quick update - 1700 miles in.

 

Dip stick won't seal properly as the rubber grommet i fashioned is not quite fat enough, it keeps popping up and has spat an enormous amount of oil into the engine bay. and all over my nice clean engine.

 

Lots of mayo in the oil filler upon refilling it and the coolant header tank is a bit low.

But appears to be pressurising correctly as hit hissed when I undid the cap.

 

Fingers crossed these are not related and i've just pinched a breather pipe somewhere / there is a small pin leak.

 

Also the heater blower blows extra hot when I boot it, i put this down to the proximity of the heater matrix hoses to the exhaust manifold, although i had not noticed this previously.

 

I am due to replace the coolant hoses with Samco/ equivilent items this week either way..

 

Cheers

 

J

[kyepan 291]

Another update... This is Dave, Dave runs Maniflow, Dave and his boys made me an exhaust a couple of weeks ago, it works very well to broaden the spread and amount of torque.

 

Need to get the engine on the rollers to prove the significant improvement in low and midrange torque i and others who have been in it feel. It's more like Pauls 6 engine now with a shove at 2.2k and 4.4k.

 

Digest this and absorb the details, more to come.

 

on minor notes, the vibration at 5500 was the inlet manifold touching the radiator, a rubber peice of pipe here has sorted this out, it now sounds smooth to the top, my fears about the lifters loosing pressure in the slightly marked bores have been finally allayed.

 

dip stick is fixed.

Edited April 17, 2012 by kyepan

[kyepan 291]

couple more photos.

 

and

 

and

[welshpug 1,657]

nice long primaries