[engine_work] Tb'd Tu 1.6 16v Build

[Sandy 191]

I heard from James a while back when he wanted one of my 16v DCOE inlet manifolds for his 106 GTi, which was already running forged pistons, Longmans head (standard valve sizes), cams (Piper IIRC), exhaust manifold and Jenvey TH bodies on a Chadil manifold with KMS ECU.

 

James and a DJmini fitted my inlet to the car and it clearly needed mapping as a result, so james brought the car along to our last Haynes trackday, for me to do a quick revise on the map, to ensure it was safe to drive all the way down to me for a proper rolling road mapping session.

 

When they arrived, the car had clearly developed a serious tapping that indicated a failing hydraulic lifter. so all plans were off and James and DJmini sadly had to take the car away on a trailer and strip it down.

 

Shortly after, James asked me to take the car, with a stripped top end and rebuild it, with new cams, pulleys (one was damaged), solid lifters and set it up. This represents an entirely fresh look at the car and a chance to create an interesting engine! Ooh I love my work!!

 

I quickly got some Catcams and the ancillaries on order, which despite the cams being non-stock, they arrived extremely quickly (thanks QEP!) and I took a look at the head.

 

The head was not what I expected, the valve throats were sharply back cut into the port, something I've seen before on an 8v head (which was also allegedly Longmans, but I don't know for sure, so don't quote me). I took the head down to Mark Shillaber at SRD to get his opinion and we couldn't see any reason why this would be done on purpose and Mark was quite adamant that it would limit the top end power. I asked mark to revise the throats and seats to his preference, which he agreed to do at a very reasonable price and four days later I got the head back with the work done and some additional chamber work as a bonus!

Before:

 

After:

 

I'm looking forward to seeing how this turns out!

[danpug 1]

Will be interesting to see how this one turns out, especially as longmans charge so much for their work.

[Sandy 191]

Well, this build seems to be in charge of it's own destiny! The piston clearances on three of the pistons was 4-5 thou, which is usable but a little slack for a fresh engine, the company that bored it might have been a little cautious. The 4th piston however had a massive 11-12 thou clearance, which is way too much and was responsible for the noise that prompted the strip down. The machinist I use reckons the dodgy one had become weak around the skirt. He also observed that these pistons (JE 79mm) didn't allow enough small end side to side float, which resulted in offset wear patches on the bores, (after only 15 miles). The up shot of this is that a rebore and 79.5mm pistons became necessary. That'll make it 1628cc.

 

Changing the pistons meant considering a change of rods, which James was keen to do. I've chosen to use slightly longer rods from another engine and shorter pistons from yet another engine to get the geometry I wanted, I'd prefer to keep the details of this to myself in case it works particularly well! The effect is to slow piston deceleration and acceleration around topdead centre, which changes the way the cam timing works slightly (one of the reasons the S1 and S2 106 Rallyes have very different natures using the same cam); it also reduces rod bolt tensile stress for a given engine speed to some extent.

The rods need the small end bush size changing for the pistons, but beyond that it's straightforward.

 

My machinist will bore the block using CNC boring/honing equipment which gives a highly repeatable level of accuracy and perfect honing, which with matched rings fitted means the rings bed in almost immediately. Combine this with selected bearing shell clearances and running in takes minutes rather than weeks, so once the mappings finished, it'll be ready to go. It's not cheap, but it's consistent and saves hassle.

 

Here's a pic of one of the rods against the OE one:

[djinuk 2]

i am really loving these project builds, you give me something interesting to read all the time

[Sandy 191]

Thanks, glad it's appreciated!

[Batfink 201]

shame its not gone to plan but i am certainly interested in what this engine will produce

[Sandy 191]

The end result will hopefully be well worth the effort for all of us

 

In the mean time, sexy pistons:

 

[Sandy 191]

I've been waiting for the re-bushing on the rods and block boring to be done. The engineer I'm using for these operations is renowned for his precision, but sadly, he's very busy and slow as a result!

 

In the mean time I've been doing a few nick knack jobs. I've finished porting the inlet manifold to match the head and set about re-furbishing the TBs, because they were looking a bit "used".

 

Before the cleaning, I reamed the top bolt holes slightly, so you can get a caphead screw past the injector boss, this makes fitting them easier:

 

Onto stripping out the injectors, idle screws and TPS etc, then removing the butterfly retaining bolts, taking great care to apply a gentle torque, it's very easy to round the head of the bolt:

 

Once all four bolts are out, turn the spindle to 90 degrees and the butterfly plates slide out. I number the plates so they go back in the same place, probably not essential,but no harm either:

 

With the plates out, the spindle should slide out easily, be careful of the spring as it comes out:

[Sandy 191]

With the spindleout, the end seals can be carefully removed. Ideally they should all be renewed, but if still soft and undamaged they will go again:

 

I clean up all the parts using Scotchbrite and AG engine cleaner, then re-assemble with graphited grease on the spindle bearing sections, taking care to correctly locate the return springs. When refitting the plates, fit them loose first and hold up to the light to ensure they are as near central as possible and not against either side:

 

When you're satisfied there are located, a dab of stud lock on the bolts and tighten them sensibly.

One down, one to go!

Here are the Catcam pulleys and single springs:

[Rippthrough 98]

Always good fun bringing up an old part like new again

 

it's not particularly important for the throttle plates to go back in the same bore as they never go back in exactly the same position as before anyway I've found - even when being careful centering them up as close as I can they always need re-balancing afterward, think it's movement on the screw thread more than anything.

 

I was sat drooling over the catcams pullies on show yesterday, but can't justify the cost on my 8v really.

Edited January 11, 2008 by Rippthrough

[Sandy 191]

You can mill down a late XU 16v adjustable pulley to fit, on a budget

[Rippthrough 98]

You can mill down a late XU 16v adjustable pulley to fit, on a budget

 

 

I've got an old piper one off Jrod but the catcam adjustment method looks far easier to play with.

 

Problem is mine is being done via arse dyno so that doesn't really help matters, as if your not careful you just pick up changes in torque rather than the actual amount of torque.

Got any recommendations as a rough starting point? - I was at 4 degrees advanced on my TU3MC cam but the TU3S cam I'll be using now appears to open slightly earlier anyway.

Edited January 11, 2008 by Rippthrough

[Sandy 191]

Ear dyno works fine LoL, if it sounds nice, who cares

 

2 degrees advanced from split lift or thereabouts if often a sweet spot on these.

[Rippthrough 98]

It'll sound nice enough on the single inlet, but it tends to be a blare rather than a sweet note, just need to get the 'bodies sorted out!

[Sandy 191]

Yesterday I set out to get the valve clearances done so the head could be rebuilt, but hit a minor obstacle! The solid followers I get for the TU 16v are made slightly too long, which means you can grind the valve stems down slightly (in the lathe for precision and flatness) to get the correct clearance without needing shims. The method is, build the valves into the head with springs, then one at a time, fit a dial gauge under a valve, on the chamber side, then with thew follower fitted, put the cam in the head (with that valve on the base circle) and screw down the cam carrier. The valve will be lifted by the amount that the valve stem is too long, you add the desired clearance to that length and grind the total amount off the valve stem to get highly accurate valve clearances!

The only trouble is, this head has been fitted with non-standard valves, which weren't being lifted when the cam was fitted, so it quickly became apparent that the valves weren't standard length, so I measured one:

 

Standard length is 104.4 and the heads of the stems hand clearly been ground by hand before and were running around 1.3-1.35mm shorter than standard, which is a bit dodgy on hydraulic lifters. Why on earth this was done isn't clear, I got Dan to measure the base circle of the old cams to see if it was bigger than normal, but it wasn't. Answers on a £10 note please? It certainly might explain the rattly valve train the engine suffered before.

Anyway, the upshot of this is that I'll have to grind the stems further to enable the use of shims, doing this job twice! (Dammit!)

 

All good fun as usual!

[Sandy 191]

It got even more complicated this week. The shortened valves made it impractical to use shims with these followers, which only became clear after I'd spent several hours measuring and rechecking all the corrections needed. Almost a couple of days lost to this sadly! I hoped James might have a spare head with some factory valves we could use, but he didn't have. So new valves have been sourced and back to it on monday, to sort the clearances once and for all!

 

Here's a pic I took during the process last week:

 

Do the clearances for solids requires care to keep parts clean whilst grinding and generally making a mess!

[Sandy 191]

Finally got the tappet issues sorted and the block and rods are back from machining.

 

DTA E48 loom:

 

Inlet tract view:

 

Head parts laid out for assembly:

 

Using a small socket to fit stem seals:

 

79.5mm bored block, rebushed rods and ACL bearings:

 

More to follow

[felix2566 2]

Sandy, I love your posts! They are so gret to read. Thanks for sharing a it all with us, so many other engine builders/tuners are so secretive about what they do. I realise that you will not be telling us all the details, but seeing how these things should be done is brilliant!

[24seven 104]

2nd that. I'm not that interested in TU engines, this thread and the 1.4 carb thread are really interesting.

[luggy 13]

Very informative, Ive only become interested in the TU engines since Ive starting using the other halfs citroen Xsara 1.6 after the demise of my 1.9gti.

[returnofjim 0]

This looks very nice

[Rippthrough 98]

2 degrees advanced from split lift or thereabouts if often a sweet spot on these.

 

 

Managed to play about on the roller for an hour yesterday while the buggy was getting mapped, ended up at 3 degrees advanced for reference, give lot more midrange without really loosing anything up top.

 

I'd actually set it at that from trail and error, so my arse dyno appears to work.

[Sandy 191]

Excellent, it will be inlet and exhaust geometry dependent of course, but that's good to hear.

[Rippthrough 98]

Excellent, it will be inlet and exhaust geometry dependent of course, but that's good to hear.

 

 

Handy rough starting point for the lower-spec builds anyway, seems to be roughly that point that works well.

[huckleberry 0]

It's threads like this that'll make you realise that building an engine should be left to people who know their stuff. Keep us updated, it's a great read!