[engine_work] Twin Weber 1.4 8v Build

[Sam 4]

34s aren't worth it on 40s.

 

Good work Sandy! Glad to see you're getting it right first time. Carbs took me ages - handy having Colin to make bits up!

[stu_woac 1]

good to know maybe trying someone new it the new year to set up the car again with the new cam coming and the megajolt on

[trogboy 17]

I'm using 32's aswell as the 34mm chokes that were in the carbs from the TU24 made it a pig to jet correctly at low rpm. Funny how they work on the 1294cc engine though.

[Sandy 191]

Here's a quick video in the rollers before things went a bit pear shaped, the fueling is still being worked on here, so it splutters occasionally, turn it up to full and you're still not close, 8v music

 

http://temp.noboost.com/sandy/JGHvid01.wmv right click save as

 

Thanks as always to the amazing travelling Sam for the hosting

[24seven 104]

any moe updates on this? It's been an niteresting read so far, even for a non TU fan.

[Sandy 191]

LoL, well, I'm currently having a K2D (non-CAT 1360) iron block bored out to 78.5mm for flat top 106GTi pistons and decked down to use 77mm stroke, giving 1490cc. Mark Shillaber is porting a fresh head for it too, which will ensure that it works with everything else. The car is coming down some time this week, then I'll be able to get back onto it fully next week. Should spice it up a bit more:)

[24seven 104]

sounds good! I want your job .

[Sandy 191]

Two weeks ago you were welcome to it!

[Rippthrough 98]

Is it just me or have we lost the photos?

[Sandy 191]

Sam's hosting has moved, I'm getting into the "new" build now,so I'll post some more pics shortly.

[Sam 4]

Sorry about that - funds seem to better spent on beer and women than domain names these days

[Sandy 191]

Haha, that's fair enough!

[cybernck 402 1 Cars]

sandy> you could have (and can!) upload pics directly onto forum / into posts - that way they won't dissapear .

[Sandy 191]

Things are starting to move forward again with this project. This morning I set about preparing the head for re-assembly. It's been worked by Mark Shillaber (SRD), the work carried out on the head is pretty minimal; as I've said before, the basic design of this head is very effective and it's easier to spoil than improve! The work he's done is aimed to complement this exact spec (use, capacity, cam, compression ratio, bore size and induction in particular, rather than producing a generic "ported head") and as such should make for a responsive and flexible engine as well as a good spread of power.

 

I thought it was a good time to demonstrate a layman's method of measuring the chamber volume:

Start by inserting the inlet and exhaust valve with grease or Vaseline around the seat to effect a seal, if the springs aren't fitted. Fit the spark plug. Set the head up upside down, using a spirit level on the gasket face to ensure it's very level. Mix up some water with a small amount of washing up liquid (breaks surface tension and lubricates the syringe seal).

 

Draw up about 50cc of the water mix into the syringe (assuming the chamber will be less than 50cc, more for bigger chambers), check the amount in the syringe (eg 50cc), make a note and slowly, carefully fill the chamber until the level of the water comes level with the head face, not higher or lower and no bulge! Check the remaining amount in the syringe (eg 17cc) and note it. The difference between the two amounts (eg 33cc) is the chamber volume.

 

Suck the water back out and quickly towel dry the chamber to avoid corrosion, job done!

 

The professional way is the use a glass plate and burette with parrafin, but unless you have that equipment, this will provide a decent guide.

 

To calculate the total chamber volume, you need to add the head gasket space and any piston dish that exists, if the piston has an intruder, that needs to be subtracted from the total. The static compression ratio will be (using cc as units for all):

(total chamber volume + swept volume) / total chamber volume = static compression ratio

Swept volume is ((half bore x half bore) x pi) x stroke using cm as units.

 

Finished with that I cleaned the head and valves ready for assembly:

 

Thanks to Johnny for the hosting

Edited January 11, 2008 by sandy309

[Rippthrough 98]

It's amazing just how much better that head is than the TU3S head I've been working on - makes you wonder just how much power the 's' must be giving away to an engine fitted with that head.

 

Nice work.

[Sandy 191]

Cheers! From what I've seen the TU3S head generally comes in about 15-20bhp lower spec for spec.

[Rippthrough 98]

Cheers! From what I've seen the TU3S head generally comes in about 15-20bhp lower spec for spec.

 

Ouch!

 

I had to a hell of a lot of work to this one before I felt happy fitting it - and even then I know it's still nowhere near where it should be because of time/money constraints - should have just spent a little cash and started with an XSi head really. Ah well, live and learn.

[Sandy 191]

You have to build a bottom end to match it though, to get the CR and squish right, it's not cheap or easy!

[Rippthrough 98]

You have to build a bottom end to match it though, to get the CR and squish right, it's not cheap or easy!

 

I could have got some rods cheap to suit but given I needed to have my car running within the week

[Sandy 191]

A bit of progress....

 

The block's been bored and decked and I've cleaned and painted it. I'm using 16v pistons to get the flat top with 78.5mm bore. To ensure there's enough room to swing the cam if I need to, I set up on Colin's mill to make cut outs.

 

A few tedious hours later! My machining skills aren't the best, but the accuracy is what's important and I'm alright with that (usually )

 

Just got to clean the pistons up now and it's dry build time.

[Sandy 191]

At last an update! I've been beavering away on this on the quiet.

 

Finished the bottom end this morning, I'm particularly proud of the oil pump, it came out of a fairly low mileage engine, but had a spectacularly thick coating of oil varnish on it, regrettably I didn't take a before pick, but here it is after being cleaned and rebuilt:

 

I got the head off the car earlier and it would appear that the head gasket seal was quite poor, probably from overheating. The radiator seemed quite choked up, which could explain why it got hot. The parts all appear to be salvageable and hopefully the new bottom end and head will make it rather interesting!

[Sandy 191]

What a day, I'm spread a bit thin at the moment trying to finish several jobs at once and the dreaded lurgy has tried its best to take the edge of things, but finally managed to get this one to the rollers!

 

The drive down was nice, the engine feels distinctly factory to drive, quite a smooth and linear delivery with no part throttle vices. It was clear that beyond half throttle the mixture was lean on the way there, so gentle was the order of the day!

 

Once strapped into the rollers it was apparent that the main jets needed changing, so Mark swapped them over (Carbs give him a chance to assert his authority/seniority over me after all the mapping jobs of late!) and I recorded the numbers and watched the temp with the laser thermo (no temp gauge on 205 Rallyes). Two changes and he brought the mixture spot on from 2000-7000rpm, a reminder of how incredibly well carbs can work when it all comes together! Then I swung the ignition a few times and settled back to 2 degrees retarded from where I started. As always, I could see where a few bhp would come from mapped ignition, but it was quite trivial really and the compromise we reached served clean part throttle manners well for a nominal loss of full throttle power around 4500rpm.

 

After allowing it to cool down to about 85-90C, we took steady state power figures, which immediately indicated good mid range and slightly curbed top end. I'm quite sure the top end is held back a bit by the OE manifold flange and standard system, something to improve later.

The estimated/corrected flywheel figures I calculated to be 141bhp at 7000rpm and 121lbft at 5000rpm, over 87% peak torque from 3500-7000rpm; which I'm very happy with. It drives really smoothly, much like Leo's 1.4 8v I did, the mid range is very evident, it surges forward around like a very healthy 1.9 does, feels nicely responsive and lacking inertia. The noise is great, if maybe a little muffled by the bulkhead insulation (here comes a wall.... window down sir, yes please!) and the blips of the throttle are instant and crisp, which is nice!

 

Here's the graph:

 

Something else worth mentioning is the gearshift, without doubt the best "factory" type gearshift I've had in a 205. I bodged it up out of XU and TU linkage parts, but it really is refreshingly nice after all the MA boxed cars I've been driving lately.

 

Here's the final spec:

77mm stroke 78.5mm bore (1490cc)

Pocketed TU5J4 pistons, TU5J4 rods (floating pin)

Iron TU3 pre-Cat block overbored and decked to suit.

TU3S flywheel with 180mm clutch (which really feels on the limit!)

TU5J2 (1.6 XSi) head ported by Mark Shillaber, standard valve sizes

Catcam 4900646 and adjustable pulley

Sandy custom inlet manifold and Weber 40 DCOEs

Colin custom tubular engine mount to accomodate inlet!

TU3S Distributor

Ti 4 branch manifold and standard 1.4 system

Picasso BE4R gearbox

309 GTI shafts and uprights (309 base model TCAs fitted)

[jonnygoodhand 0]

To say I'm 'over the moon' with this would be an understatement!

 

Many thanks, Sandy. I look forward to reporting back on here soon with comments on how it drives and what fun there is to be had with it!

[jonnygoodhand 0]

Collected the car and couldn't be more pleased!

 

During the long journey back home (200+ miles) up the M5, it was the mid-range power which immediately struck me. Now I've had chance to have a spirited drive along some local roads, the engine's overall power is now apparent. And don't get be started on the sound!

 

Absolutely fantastic! Thanks for all your hard work Sandy.