Tassuperkarts GX Turbo (Updated again!)

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When I finally get around to piffing the standard ECU I'm totally gonna pick your brains...

shit I been doing that one way or the other since I got on here
time well spent so far

[tassuperkart]

Sure gents. easy as!

I found a slight setup glitch on the Microtech where I had inadvertanly plugged channel 2 of the ignition system into the dizzy/tacho output of the ECU.
Still ran fine but tended to kick back when cranking.... my bad!
Fixed the slightly loose power supply pins in the ECU plug as well so no more cutting out!

First job was to do cold start setup. Temps this arvo were up a little at around 15deg.c so I just guessed the settings below that based on what Id arrived at further up the temp ranges. hafta wait for a very cold morning to trim up the very cold ranges.
All I needed was a little more cranking fuel at lower temps and about a 5% enrichment at about 50 degrees and above. Some minor adjustment on the cold trim table was all that was required over the cold map on the FJ20.
This little ET engine is carrying quite a big cam and is quite tolerant of strangely large cold fuelling adjustments. The FJ20 would not tolerate more or less fuel around what was about right when cold running. A couple of clicks either way of smooth resulted in rough and hunting cold idle on that engine.
I set the much cammier ET engine on the richer side of the range just for reliability.

The E15 warms up quite quickly tho so you have to be quick!
Some further tweaks between hot cranking fuel and after start enrichment results in robust and repeable quick starts from hot temps.

So took the Rat out for a run for some quick onroad tuning sans WBo2.
Unfortunately, my new AEM WBo2 uses a sensor with a bloody M18 x 1.5 whereas the Techedge uses a M14 x 1.5...arrrgh.
I didnt want to puill the TechEdge out of the Ute of Death as it interfaces with the ECU in that car for adaptive tuning and closed loop running.
So I gotta mess around now with changing the weld in bung before I can fit the AEM......

Anyway, just some tweaks here and there to smooth out off boost running and some timing tweaks to smoothen it out.
Its not too bad to drive at the minute but Ive only flicked it up onto boost a few times just to see.

Now, a few setup issues I have discovered.
First, as previously mentioned, the injector wiring order can be gotten out fairly easily by following the wrong wiring diagramme in the manual.
Make SURE that you use the pinouts on the Ver. 2 diagramme if thats what you have.

Secondly and importantly, I found i was getting fairly wild MAP pressure swings when the map line is connected to the usual spot on the back drives side of the runners.
It appears that Microtech have far less map filtering applied than the EMS system I was using as the EMS did not display any map variations I was aware of.
Reason for this is that port is only actually looking at 1 runner fully and the map line is subject to unstable and varying map readings.
This is made worse when using lumpy cams which have the engine idling in lower map ranges.
Always connect the map sense line to a point within the PLENUM, not one of the runners.
NEVER share the map line with any other source of air such as blowoff valves, dash guages and the like, other than the fuel pressure regulator.
Any bleeding of map pressure further along the shared line, suich as vac ports on the charcoal cannister and so-on can reult in innacurate or varying map readings.

Another trap for new players is grounding of the ECU wiring.
It is crucial to the correct and stable operation of the ECU that there is no electrical noise generated by ground loops.
In particularly dodgey setups there can be enough potential to mess with the head of the ECU at very least and at very worse, electronic component failure and tracks blown off the circuit board.

Never mix and match grounds on the engine AND chassis and in particular, wiring for temp sensors. Temp sensor circuits are very susceptable to noise.
They must ground right back at the ECU.
Usually, all components in the EFI system are held above engine ground anyway so thee is no need to attach wires to the engine.

All grounds coming out of the ECU should be securely bolted to a bright and clean chassis ground point, closer to the battery the better.
ECU power supplies should also be brought in from as close to the battery as possible as the battery woks like a kind of dampener against voltage spikes.


Now, lastly, I have been experimenting and I found that the dizzy output drives the stock tacho via its resistor perfectly!
This should save having to fit all those funky diodes i have seen on multiple coil setups.
My tach works a trea now driven soley by the ECU.

Addendum to this. The tacho will only work if the ECU has been configured with a distributer output. tried this setup on ETKings LT-8 and it didnt work.

More later
Oracle

[tassuperkart]

been doing a lot of road tuning with the new AEM WBo2. it got hot while I was out and spat water from the expansion bottle.
I had trouble with pressurising the water system. I originally thought that id buggered the seal of the HG because I had forgotten to retension it after initial fitting.
Anyway, Head had to come off one way or other so i thought why not and this is what I found....Its phukked!



Phukkitt.
I grenaded a piston...................#3. Out she comes again.... mah!

Closer look:



You can easily see where the seal had been breached around #3 and was gassing into the water system and also blowing across to #4.
Surprisingly, it was running faultlessly apart from air in the water.......
I didnt hear anything at all with regards to detonation which is kinda strange.....

Bore is only lightly marked but they are .020" Duralites and I have no idea where i could get a single one from so it looks like a new set.

There is nothing wrong with the engine so just a piston would do.
Annoyingly, the 2 other parts engines I have are both on Std bore...sheesh. What chance of that?!!!

The bore is in such good order I think Ill just slip in a new set of cast pistons and wind some bearings into it... Itll doooh Donkeh! Itll dooooh!

L8r
Oracle

[zoomzoom]

any idea of the why and how

if you look in the right places you'll still find duralite still a bit of old stock around last year when I had my engine built





zooomzoom

[tassuperkart]

yer after i fitted up all the goodies and the replacement Microtech, i took it out for some light road tuning.
However this was all being done by ear as i didnt have the WBo2 sensor installed yet.

I couldnt resist the temtation to give it a couple of flicks up high and this is the result...bugger it!
Strangely, the fuelling maps "appeared' to be good enough but apparently not..........

As Ive mentioned before, If I bothered to ring around, im sure i could find some NOS Duiralites but i simply cannot be arsed when a brand new set of Hypatecs is 120 bucks!!

Shall see!

L8r
E

[Damo]

Are you sure it didn't blow between #3 and 4 first, then cry a molten river?
That seems like a wide blow mark between the two!

Damo

[tassuperkart]

Mmmmm dun think so m8
The gasket itself was not breached. The fire ring was still intact. Usually, id expect to see the fire ring burnt thru its edges that are exposed to the detonation.
It had been as hot as hell as you can see by the witness marks but most of that marking is probably just the paper part of the gasket charring and leaving the stain. The breach was all on the block side.

The pix really highlights the blowing marks. When you actually look at it under natural light, the marks are very faint.

The strange part is that the engine was running beautifully, right up to the point that I pulled the head off and apart from the slight bubbling in the water, I would have just kept driving it around like that!!!!!

What I did forget to mention in all of this was that the gasket had only been tensioned down twice cold when i installed the head. It was a cheap generic gasket and i was using old head bolts as well.
I just plain forgot to retension the head after initial run up.
When I removed the head bolts, id guess they only had about 30Lb/ft of torque on them....my bad!

L8r
E

[tassuperkart]

Heres a quick vid of it before it shat itself.
Cold start. No throttle using a stock Nissan cold idle valve.
This engine is fairly heavily cammed and ported with a lightened flywhee and this vid proves that with a little patience, you can makea Microtech MT-8 run well from cold!
So next time someone tells you you cant make old Microtechs run well at cold then refer them to this video.

Damn those little digi-cams make the engine sound clattery tho!. Its nowhere near that noisy!!!!!!!

[tassuperkart]

Some goodies arrived yesterday.

New pistons.



$116 for all four delivered. Cant do better for a high siliucon cast jobbie!

I got a set of full chrome rings.



$84 dollars!

Also a full gasket set



A neat 200 bucks.

The last bits are the bearings but i wont know the sizes until I open the engine.

More later
E

[Damo]

Mmmmm dun think so m8
The gasket itself was not breached. The fire ring was still intact. Usually, id expect to see the fire ring burnt thru its edges that are exposed to the detonation.
It had been as hot as hell as you can see by the witness marks but most of that marking is probably just the paper part of the gasket charring and leaving the stain. The breach was all on the block side.

The pix really highlights the blowing marks. When you actually look at it under natural light, the marks are very faint.

The strange part is that the engine was running beautifully, right up to the point that I pulled the head off and apart from the slight bubbling in the water, I would have just kept driving it around like that!!!!!

L8r
E

Hairy muff.

Seems strange to have marking between the two cylinders? It may have been leaking between the two when #3 was pinging if the head wasn't tensioned to spec, but not sustained enough to cause a HG fail.

You have enough exhaust valve clearance on #3?

Nice pick up with the slugs too, same brand that my machine dude gets. $200 with rings.
Looks like they are the Unleaded ones?
What pins did they come with, tapered or the normal ones?


Damo

[tassuperkart]

To be honest M8, I dodnt clearance the valves when I fitted this head/cam combo. the previous owner didnt need to so I just took it at that. might be worth a look but unless the valves are actually touching the slugs then Im not really concerned.
Yer that combustion chamber shape is the only one they do. I dont really know if there is any benefit in one shape over the other tho.
have you found any differences?
I will bleand slightly the edge where the bowl ends out on the piston edge. Its quite sharp.
The pins are just plain parallel type. Nothing fancy!

I lied on the price of the ringset tho.
They were 84 bucks for the chrome set. Still mighty good value tho.

Thos prices I got are not mates rates or anything either. I just bought them online from Precision International in Vic.

Available to anybody!!!

Cheers
E

[Damo]

To be honest M8, I dodnt clearance the valves when I fitted this head/cam combo. the previous owner didnt need to so I just took it at that. might be worth a look but unless the valves are actually touching the slugs then Im not really concerned.
Yer that combustion chamber shape is the only one they do. I dont really know if there is any benefit in one shape over the other tho.
have you found any differences?
I will bleand slightly the edge where the bowl ends out on the piston edge. Its quite sharp.
The pins are just plain parallel type. Nothing fancy!

I lied on the price of the ringset tho.
They were 84 bucks for the chrome set. Still mighty good value tho.

Thos prices I got are not mates rates or anything either. I just bought them online from Precision International in Vic.

Available to anybody!!!

Cheers
E

I was thinking valve clearance for the fact that #3 'maybe' to small! I have seen a difference of a good few thou clearance over the duration of the heel of a stock cam I had in the past. Probably the combination of the cam tunnel being slightly worn as well as the stock cam bearing surfaces. You may be cracking the exhaust valve mid stroke if the valve gap is too small.

As for the slugs, it's a little hard to tell from the pics. They look like unleaded turbos. IMHO the leaded version is better, 1mm thicker top ring land at the expense of 1mm less head clearance.
I would expect the price of mine would be retail also.

Somewhere in the past I must have picked up an engine with the tapered pins. My machine bloke said that that sort of thing was not usually a factory issue. I wonder if they are from a N/A engine, or even a E13/16?

Damo

[tassuperkart]

Ahhh my bad, Im with you now about clearance.
No, I check that quite thoroughly and that usually reults in burnt valves!

There must be a legion of small engines that use a similar bore and pin diameter and somewhere in there would be tapered pins. Id be thinking motorcycles myself.
Its all engineering standard stuff as far as pin diameters and blah so no biigie Id say.
Benefits? Hard to say. Depends on RPM but at most sane rpms might not justify the cost.

Id actually prefer to ream/hone the rod little ends, drill for oil and fully float the pin and use teflon buttons to center it. Cheap, effective and proven.

Thing is, cant be arsed frigging around like that when chasing 7000rpm max in a shitter like these......

The Bosch 36's are very close to going in BTW. Will go back in with the rebuild.
Did some reading up. Very best we could hope to achieve realistically with these injectors is about 380 to 390cc and that would be seriously stretching it.

Only ECU's I know of that will employ 100% duty are Honda.
They max their injectors at 85% then just hold them open after that.
Must have some funky method of staging the peak and hold ratio between pulsing and DC id say. Otherwise injectors would get mighty hot!
Makes me wonder how they manage between 85% and 100% flow when they pull wide open.

Newhoo
E

[tassuperkart]

Not much progress to date.
best new is that my really good head is not cracked anywhere.
The pistons are at the engine builkders being fitted to a set of rods.
because the nose of my crank is slightly damaged, ill probably use the cran out of the spare engine. Its standard size on the pins and mains. ill wait until I pull the existing crank out of the block before deciding. well see what the micrometer says.
Once the ARP suds arrive it will be all ahead full.

More later.
Oracle

[baz]

Whose your engine builder?..Obviously you will do the majority of the labour, but whose fitting the pistons to the rods?