N13 Turbo - Round 2... Fight!

Converting To Delco ECU From Carby Or Other Injection Systems
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vlad01
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Re: N13 Turbo - Round 2... Fight!

Post by vlad01 »

Nah, that's alloytec v6.

As far as ecotec 4 cyl, only real issues I've seen is the coil packs are garbage and the rocker cover seals are akin to the E series falcon ones (shite!)

But that's doesn't make the engine itself bad, far from it evidently. Mechanically they are great, just the cars and surrounding parts that GM have them in are shithouse, cough cough Cruize :? :lol:
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Re: N13 Turbo - Round 2... Fight!

Post by Charlescrown »

They do look like a very strong engine. Similat to the Ford Ecoboost engine. It's a shame the GM engine didn't come out in any cars here. If they did they would be a good engine swap on some older Jap buzz boxes.
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Re: N13 Turbo - Round 2... Fight!

Post by vlad01 »

Heaps of cars here had them, Cruize, Astra, Opel imports, few other models but I can't recall exactly which.

Everyone is saying the ecoboost is shite, something about the liners and head gaskets iirc. Lot of failures. Interestingly the ecotec 4 has both close and open deck options but don't seem to have any issues with the open versions, where as most other makes have issues with open decks and the cylinders walking.
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Re: N13 Turbo - Round 2... Fight!

Post by BennVenn »

If you haven't seen his channel, a guy called Matthew Chevalier is building a turbo 1.8 ecotec. An interesting build (https://www.youtube.com/@cmattdabrat) It's finally up and running but has been a bit of a struggle. The block seems fine and he's putting a fair bit of boost through it.
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Re: N13 Turbo - Round 2... Fight!

Post by BennVenn »

Pulsar is back up and running. A few afternoons on the dyno to get the tune a little better and it's now showing good gains for every 10kpa of boost added. There's still a fair bit of blowby even after running in the rings but that might be down to the 0.6mm ring gap and the oval bores. Replacing the well worn (1 broken) rings only gained 5kw at the same boost level. I guess that proves ring gap in a turbo engine doesn't loose you very much power.

105 wheel kw seems to be the limit of the fuel pump, any higher and I see VE jump from low 80's to over 100. It's running genuine XR6t light blue injectors (440cc?) but only at 3bar. The stock pump didn't sound happy at 4bar which is probably close to where the fuel pressure is under boost. I'll put the new 255 pump in there and increase fuel pressure to 4bar to get the rated 440cc and see how it goes.

My ARP rod bolts finally arrived. I'm not sure if I need them anymore, at least not with this cam. There's no more power to be had past 5500rpm so the stock bolts shouldn't be too stressed.

105wkw feels good, much better than the previous 81kw and heaps better than the stock 48kw. Probably not as fun as 120kw...
104kw.PNG
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Re: N13 Turbo - Round 2... Fight!

Post by BennVenn »

New high score! 115 wheel kw!
PB_115.JPG
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I couldn't crack 105kw, even with the new pump. AFR's were good but more boost just = less VE and the same 105kw.

The same thing happened with the GT17 but at around 85kw so I was pretty sure it was back pressure related, and therefor valve train related.

I ordered a bunch of valve spring shims from precisionintl.com for a couple of dollars for a set. Went ahead and first measured valve seat pressure using a load cell to measure the force to crack the valve from the seat. Comparing that to the workshop manual showed valve seat pressure was well under spec, 240N vs 300N on the exhaust valves. Intake were within spec. I assume it was from previous valve seat work, or maybe a stretched valve. It wasn't a weak spring as changing exhaust and intake springs maintained 300N on the intake.

I went ahead and measured the valve spring bind height using the mill, compared that against the open valve height and worked out how much I could shim it while maintaining 60thou clearance for spring bind.

I ended up fitting 1.5mm shims under the springs and when the head was rebuilt I now measured around 350-360N on both intake and exhaust.

A little bit of math on seat pressure and valve face areas says there was only 34psi of pressure holding the valve shut at 240N. I'd say at 12psi boost pressure, there'd be at least 25-30psi turbine back pressure so I think that was the issue here. Now with the 350N on the seat there's over 50psi holding the valve shut which assuming the same backpressure ratio should easily see me running a bar of boost before valve float issues.

The goal was 120wheel kw so I'll add in another psi and I think we'll get there.
head.jpg
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seatheight.JPG
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Re: N13 Turbo - Round 2... Fight!

Post by Charlescrown »

You also need to consider those specs are for a NA engine. Add the boost pressure to the surface area of the back of the inlet valve and up goes the required spring pressure. It really become a dog chasing it's tail till it catches it.
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Re: N13 Turbo - Round 2... Fight!

Post by BennVenn »

Intake valves don't really have the same problem as exhaust. As soon as the intake valve opens and the cylinder fills there's no difference to NA. Both sides of the valve have pretty similar pressures on them as it is closing and by the time the valve seats, cylinder pressure is already higher than manifold.

The issue is usually the exhaust side where you've got significant turbo backpressure forcing the valve open plus the partial vacuum in the cylinder as it tries to draw in the fresh charge. At least that's the theory from the experts anyway. But yeah, it seems its a bit of a balancing act to get everything working together nicely. Too much spring pressure or rate and then you get lifters deflating and other valvetrain issues... Surprised it works as well as it does just bolting on a turbo to a NA motor

I know increasing boost with a supercharger has its own problems but I think they might be from higher pressure pulses?
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Re: N13 Turbo - Round 2... Fight!

Post by BennVenn »

Small update:
N13_18LE_TD04L_11Aug23 (1).PNG
Valve springs seemed to have done the trick! Now making 125kW at the wheels which is about all this TD04 can flow. Going higher with the boost makes more power but VE drops around 15% at 5500 at 13psi compared to 11psi. The stock 2" cat is probably part of the problem.

All of my new exhaust valve stem seals have failed, or have popped off. Maybe the intake too... Is this common? I pressed them all down firm with a socket, took care not to damage the lip when installing the valves. I guess the head will be coming back off...
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Re: N13 Turbo - Round 2... Fight!

Post by Charlescrown »

Good to see an update. Very curious why your saying the VE is dropping off with higher boost? The valve stem seal is one I have not encountered. Can you post a pic of one?
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