[engine_work] I Forgot How Much I Missed It!

[DrSarty 90 1 Cars]

Cost and financial situation at the time.

 

It never had a Cu HG; your getting my engines mixed up. As Dan said, after 3 years of use, the rings on cyl 1 melted and trashed the bore. Honing or rebore (to 87mm) was an option, but new forged pistons and all the other costs meant it was time to cut losses.

[kyepan 291]

shame a new block would have sorted it, what happened to the pistons etc.

[DrSarty 90 1 Cars]

RR graph as requested/promised:

 

 

Justin:

As said, I didn't have the financials to repair the 2.2. Pistons were sadly binned, as it was proving tough to get a single 87mm custom piston to replace the damaged one; but that would've been dependant on a block hone (still at 87) being suitable.

 

Otherwise a rebore to 87.5 or 88mm would've cost, plus new pistons and a remap, and we'd have been over a £1,000 in new costs fairly quickly, on top of all the time and effort to lift it out and do the work. I had to cut losses, sell up and walk away for a bit. It was a bit like a sensible, tactical 'fold' in a hand of poker.

 

The car is certainly lively with this engine, and I suspect it'll improve or perhaps mature with age as it beds in and then gets bodies, new exhaust, staged injs. and a remap.

Edited August 7, 2013 by DrSarty

[welshpug 1,657]

looks a classic MI16 curve, allbeit peaking a little high, personally I'd fiddle with the cam timing, but that can wait till next time round on the rollers

[Anthony 1,003]

Is that a completely standard D6C/XU9J4 1.9 Mi16 other than the GTi-6 inlet manifold and air filter Rich?

 

All looks nice other than that hole in the torque curve between 3200 and 4500, something that I've seen on other 1.9 Mi16 graphs too. Interesting that the inlet and management/mapping doesn't really appear to have changed that seeming characteristic of Mi engines at all.

 

Should make a good comparison to the 'bodies when you get them fitted and mapped

[kyepan 291]

i'm sorry, did you just say you just binned three perfectly good forged pistons because of a blown ring on one?

 

Surely the cheapest option would have been to replace the block... and buy one piston...120 for the piston, 50 quid for the block plus perhaps a hundred machining to bore it out to the existing spec! plus rings...

 

Curve looks standard MI as ant said, if you want to go home brew on the inlet, look up tumble, spin, with reference to inlet charge and fuel atomisation. What happened to your existing bike bodies? as i know someone who might be in the market for a set.

[DrSarty 90 1 Cars]

Let's stop dwelling on the old engine. Melted piston rings into melted piston with associated bore damage = big costs. I had custom pistons including custom gudgeon pin height etc so it was nowhere near as simple and as low cost as you keep implying.

 

The current engine is a freshly built D6C, so CR is still 10.4:1. Cams however are PeterT stage 2 inlet with stage 1 inlet as an exhaust, on OE No.4 and No.2 cam pulleys respectively. As a result, Dave Walker believes it's likely there's quite a bit of valve overlap. We did indeed struggle to get it to idle.

 

As a potential result, coupled with the long inlet tract, with a single throttle body a long way from the valves, low speed and light throttle is a little lack lustre. However it comes to life when pushed.

 

Dave's advice - and remember it was due to get ITBs anyway but they weren't ready in time - is getting the throttle butterflies much closer to the valves, improving torque linearity and overall performance.

 

Minor additional mods include no resonance chamber on the inlet, GTI6 injectors and a non-heat conductive 10mm 'gasket' between the inlet manifold and the head.

 

I'm a little unhappy with noisy tappets/lifters, but when it gets the ITBs, I'll also do the following:

> Kent vernier cam pulleys

> 0.7mm Cometic HG to increase CR nearer 10.8:1

> Freshly refurbed lifters

> New exhaust, ITBs, staged injectors etc

 

That said, this thing is seriously rapid and I can't complain. It's put the thrill back in driving. I've received multiple flattering comments and several cash offers in the last week alone.

Edited August 7, 2013 by DrSarty

[petert 586]

Sounds and looks like the inlet is advanced a bit too much for what ever reason. It shouldn't be rolling off so fast at 7000.

[DrSarty 90 1 Cars]

Thanks Pete.

 

I'm pretty sure I put on the OE cam pulleys as advised by you. Pls confirm that was no.4 on the inlet and no.2 on the exhaust was correct, or the other way round. Perhaps I cocked up!

 

Also, when I mentioned 'lack lustre', that was a bad choice of words. It responds instantly, but at slow speeds and low RPM it can be a bit 'digital', i.e. on off and difficult to drive smoothly. Anywhere else it's responsive, aggressive, smooth and rapid, and downright nasty coming on cam!

 

Anyway, it's fine until phase II with the bodies etc, and I don't want to fiddle with the cambelt (in the limited space) until absolutely necessary. When it's got the verniers on we can live adjust on the rollers.

 

Out of interest, if the inlet was retarded a little, how would the curve/graph change?

 

Also, when we met at lunch, you mentioned the exhaust timing might need tweaking also. Based on the graph is that still the case?

 

I assume that without the 7k+ rpm torque roll off you mentioned due to the over advanced inlet, we'd see higher BHP? But where would the compromise be?

Edited August 8, 2013 by DrSarty

[kyepan 291]

iirc should be number 2 inlet, number 4 exhaust, still don't agree about binning the old pistons but it's your party.

 

#4 inlet is more advanced for more top end

#2 is less advanced for more midrange clout

 

You won't see more bhp with a #2, but it will come on stronger sooner, filling in a portion of that hole in the torque curve.

 

J

Edited August 8, 2013 by kyepan

[petert 586]

..

#4 inlet is more advanced for more top end

#2 is less advanced for more midrange clout

Wrong way around.

 

#4 inlet is more advanced for LESS top end

#2 is less advanced for more top end

[kyepan 291]

s*it, you're right.. i'm going mental.

[petert 586]

The shape of the top end suggests either inlet is too advanced or insufficient compression. Before any more changes, I'd give it a compression check. Regardless of the actual hp figure, with those cams the power should extend to 7300-7400. It will also have significant overlap, making idle lumpy on a single plenum manifold.

[DrSarty 90 1 Cars]

We've had a mechanical failure; it went pop at Emerald last Monday.

 

My friend Guy and I, combined with a wee conversation with MadScientist (Pete) have a considered opinion which I'll add at the end of this post. We've discussed it for hours and hours and symptoms seem to lean to one conclusion, but I'd appreciate others reading through the below chain of events, facts and changes and offer some ideas.

 

Previous State (results shown with above graph)

> Freshly rebuilt XU9J4 (alloy, 1.9) engine bottom end and head

> OE head gasket (10.4:1 CR)

> PeterT stage II inlet with stage I inlet as exhaust

> OE 8 branch Mi16 exhaust manifold to OE GTI system (after about 2 mths, there was a slight rasp in the exhaust that made me think a baffle might be loosening)

> Temporarily fitted GTI6 inlet manifold (no resonance chamber or IACV, IAT hole & res. chamber holes bunged) plus cone filter

> GTI6 injectors

 

...as above, drove well, 165bhp, hole in torque curve with huge surge to 134lbft at 4.5k rpm, lumpy idle (due to cam combo/overlap & single plenum as mentioned above) and dying off in power before 7k rpm. Comments on this above. 1 or 2 noisy tappets and slight blow from the manifold to downpipe join. Nominal temps and 6bar oil pressure at all times.

 

In this state, the engine ran without missing a beat for 2.5 months, regularly being given death, covering several 1,000 miles around Cambs, Norfolk and to Devon and back, delivering about 30mpg.

 

 

Intermediate State (after 8hour graft in workshop on Saturday 12Oct)

> Fluids drained, head off, cam bearing caps removed, brand new lifters fitted - supplied by Lyndale Engines in P'boro from a supplier. Packaged, oiled and double checked to be correct items.

> OE (4 and 2) cam pulleys swapped for Piper vernier on inlet, and DW8 OE vernier with shim on exhaust. Cams refitted, locked as per std head removal procedure.

> Deck of block and liners treated with kid gloves (not disturbed) and OE gasket residue carefully scraped off. Water jackets/galleries blown out with air line.

> Miles' 4-2-1 exh manifold fitted with stainless steel allen-keyed studs, new gasket and Aerolock nuts

> Head refitted with Cometic 0.027" (0.7mm) MLS head gasket (HG), in order to get 11:1 CR to allow cams to perform

> OE exh prior to mid section measured, cut and welded to suit 2-1 coupling of new exh downpipe

> Fresh oil and antifreeze mix

> GTI6 inlet refitted ready for ITBs 2 days later

 

(The Cometic HG was ordered via Burton Power Products at £105, custom-made in USA with 4-6 weeks del'y. Part no. was confirmed prior to fitment and cursory inspection should it to be correct, although there was a slight bow, i.e. it didn't seem to lie flat. However it could only be fitted one, correct way round (due to the head dowels and hole pattern), was trusted as being correct and we knew it would clamp up fine with head fitment).

 

...engine started on the button and idled more smoothly. New tappets/hydraulic lifters unfortunately rattling to buggery, but given time to pump up and fill. Much better behaved on the road as previously throttle was a little digital and difficult to drive super smoothly. I was advised that new lifters can be a little stubborn and take time to quieten down.

 

In this state, car driven about 100 miles, from Cambridge workshop to Peterborough and then to Emerald on Mon 14Oct. Lifters didn't quieten at all, and power tail off from 6k rpm seemed more pronounced.

 

 

Final State (where failure occurred)

> GTI6 inlet manifold removed

> Custom 43mm ITBs bolted to cut down GTI6 inlet manifold fitted

> 2 sets of cleaned and tested XU7JP4 injectors fitted to inner and outer fuel rails

> Air leak check confirmed all sealed - ITBs balanced

 

...on the rollers, the car ran for nearly 3 hours, sounding beautiful with a lovely ITB roar, idling rock solid and filling in (and then some) the previous torque curve gap. AFRs were good but there was no gain in peak torque or power, in fact power was down by about 20bhp from before!!!

 

John worked hard, and we swang the cams a little and got the power back, with a nice flat curve and smooth BHP trace, but again with the rather premature and noticeable power (due to dropping torque) tail off just under 6k rpm. Minor ignition changes were tested but reverted as they were right anyway and made no difference. He witnessed no det. All temps and oil pressure nominal still.

 

Something just wasn't right. There didn't seem to be any oil vapour breathing from the catch/breather tank at high rpm, but instead the dipstick was climbing out of its tube and oil was spitting out.

 

As there was a time pressure, John had to finish mapping before 3.30pm, and at 3.10pm when he was on part throttle loading (site 6) there was a 'pop' (almost a squeaky pop TBH), and he cut the engine straight away. He said he saw a 'puff' of something from the front when it went. It would then start, but was clattering and there was smoke and oil from the exhaust.

 

***

SIMPLE SUMMARY:

* Fresh engine on 10.4:1 CR with OE HG and GTI6 inlet runs fine for nearly 3mths

* All that's changed - very carefully - is new lifters, vernier pulleys (same timing), new exh manifold, new thinner MLS HG and ITBs

* Engine block seems to pressurise, engine goes pop with likely HG failure and probably rings too after 3hours of running

 

CURRENT CONCLUSION:

* New items deemed to have no impact/contribution to failure = exhaust, lifters and ITBs

* Only item/change deemed to probably contribute to pressurised block = new HG

 

Based on the clear diving off of torque/power at about 5.8k rpm, plus the dipstick tube spitting oil based on a likely pressurised block, we think the engine was being held back, becoming restricted as rpm raised and pressures in the block increased. I've also considered a collapsed exhaust, but I believe the AFRs and noise would've shown this.

 

But as the lifters wouldn't quieten, AND considering the apparently pressurised block, we are currently considering that the new HG was incorrectly manufactured (as it couldn't be fitted incorrectly), with either missing oil gallery holes, holes that were too small, or incorrectly cut.

 

This conclusion of the HG having missing/incorrect holes may seem a little radical, and we'd be surprised if it were the case. We haven't yet removed the engine and head to inspect matters, but John is doing a compression and leak down test in advance to provide more info that's difficult to get once the head's off. However we can't think of anything else currently. No holes in the head or block were or could've been blocked or restricted during the HG change, we were simply too careful, and what on earth would we have had to do or not do in order to do that?

 

The ITBs, exhaust and lifters surely cannot contribute to a pressurising block, can they? We don't think so.

 

The HG appeared OK, and could seen to be located correctly once the head was correctly torqued down. We followed the Haynes manual process and torque settings as usual.

 

I'll update this once the engine's out and head off, but I welcome ANY feedback whatsoever and ideas. We're kind of stumped, stuck with symptoms pointing to newly introduce crank case pressure that couldn't really go anywhere, which held the engine back until a weak link went bang.

 

Hopefully hear your ideas soon. Ask anything you like.

Edited October 22, 2013 by DrSarty

[DrSarty 90 1 Cars]

Couple of pics, plus a vid and a few more bits of info.

 

 

 

 

On the above close-up of the bodies you can see the oil spatter from the dipstick. This only started happening once the HG was changed (we don't think the other changes are relevant).

 

Listen to the (brand new!) tappets on the vid:

 

As PeterT said, power did seem to be rolling off before the major (but basic) changes, suggesting low CR and/or advanced inlet cam. CR was checked a month ago giving at least 185psi per cylinder, and inlet cam was retarded once the ITBs were fitted which found 20bhp that was missing, although the 6k rpm tail off was new and earlier than before.

 

Words cannot express how f*cked off I was when the new lifters were noisier than the original set, and how galactically f*cked off I am now. However, it's just metal and engineering and there will be a logical explanation and cause, which even if it's different to the current theory will be fact and I'll have to deal with it. It's especially annoying as I was happily driving the thing around for months beforehand and the changes were supposed to be both improvements and refinements.

 

I will pursue this, but I do have an iron block, freshly built 11:1 CR Mi engine to fit which it'll put it on the road again very quickly.

Edited October 22, 2013 by DrSarty

[wicked 103 3 Cars]

 

 

Something just wasn't right. There didn't seem to be any oil vapour breathing from the catch/breather tank at high rpm, but instead the dipstick was climbing out of its tube and oil was spitting out.

 

 

 

Do you have picture of your breather system? If hoses get blocked, strange things happen....

 

Wrt to the tapping lifters; did you double check the spray bars on top of the lifters, to make sure they are not blocked?

Edited October 22, 2013 by wicked

[DrSarty 90 1 Cars]

I know where you're coming from, but in context:

> the engine was fine before the HG and lifter change (with only a minor tap, probably from one, old, sticky lifter) - this is why the lifters were being replaced together with the fact they're old anyway

> this indicates the oil spray bars were fine, and the head was only off for an hour before being refitted again

> likewise with the oil breather system - head off, no breather system changes, head back on

 

If there had been a gap/duration of time before refitting the head, where potentially something could've happened I'd understand that changes or problems in these areas would cause other problems; but we literally took the head off, swapped HG and refitted it within the hour.

 

Upon inspection I will check all of these things, but I cannot understand why these things caused no problems before, then we change the HG, and the engine suddenly pressurises and sh1ts itself.

[wicked 103 3 Cars]

Making assumptions can be misleading...

 

For instance; you changed the gti6 inlet with ITB's; maybe a hose is bend more (or too much), obstructing the breather system or what so ever....

(Under time pressure you can overlook stuff..)

Maybe I'm totally wrong; just trying to give hints..

 

Good luck with finding the root cause...

[DrSarty 90 1 Cars]

Agreed, but no assumptions have been made - just thinking it through to a conclusion which so far adds up.

 

Breather system was already designed for ITBs, off to the side of the inlet runner for cylinder 1. The catch tank's on the side of the head. No breather hoses needed to be moved at all.

 

Everything will be checked thoroughly, however 2 things must be considered: the block pressurised (which could be kinked or blocked breathers as you suggest), but the new lifters stayed noisy, indicating bad oil feed, and breathing wouldn't affect that.

 

It's really quite a riddle which won't see clarity until the engine's out and the head's off. But until that point, the HG restricting oil and crank case pressure is the best idea we can come up with that fits all symptoms.

 

Please keep the ideas coming, as it helps to throw things around and see what sticks and makes sense.

Edited October 22, 2013 by DrSarty

[welshpug 1,657]

just a wild stab in the dark but maybe the aftermarket tappets just didn't fill up properly and caused a very high dynamic compression ratio due to the decreased valve duration from not being opened fully.

[welshpug 1,657]

has the valve clearance available been confirmed and was cam timing checked at TDC?

[DrSarty 90 1 Cars]

Hi Mei:

 

That's connected thinking and we thought that, but what would cause the new lifters not to fill in the first place? The previous lifters were filled so the oil supply previously was OK, so why would new lifters that an engine builder would fit not fill if the oil was there?

 

The cams were fitted based on PeterT's recommendation of a No.4 pulley on inlet and No.2 on the exhaust. The verniers were aligned and marked to match the OE fixed cams exactly when fitted and locked, so the start point was the same.

 

Please don't see my responses as an argument at all or a sign of ingratitude for your suggestions; it is merely a technical response and debate to batter out your suggestions and the possibilities and see what could've caused this.

 

P.S. The new lifters were in packs of 8, designated for Peugeot, Citroen and also Volvo. They fitted perfectly, and PeterT's reground cams would be expected to work with new and used lifters which were known to be good. Also, research was done in whether to prepare the lifters for fitment, and concensus was 50-50, either soaking overnight in oil or fitting straight from the pre-oiled packet. I suppose my point is why wouldn't new lifters fill if supplied with oil?

 

P.P.S. John at Emerald said they'd replaced lifters in a Vauxhall once, and eventually found that 2 hadn't filled and were locked in a compressed state. These lifters could be spun under the cam lobe heel as not under tension and hence noisy as hell. But to have all 16 locked, from new, with an oil supply...?

 

As you can tell this is very frustrating.

Edited October 22, 2013 by DrSarty

[welshpug 1,657]

highly frustrating indeed, I can't think of any further suggestions, especially now it doesn't run.

 

just need to get it apart and inspect what has gone wrong.

[DrSarty 90 1 Cars]

It does run, just noisily, and basically on 3.

 

Another note is that the HG must have blown, as coolant and temps were perfect until the funny noise.

[petert 586]

Bugger. I've missed all this. I think you should strip the engine and identify the point of failure. Then you might be able to identify a cause. I've always been doubtful of aftermarket lifters since I saw a set of Piper lifters destroy an engine.