Unigroup

We should have just went down, however there was a lot of pressure to stay back and catch up on work. Next year we'll make a better effort. I'd like to get together some cars and go down. Yavuz Unigroup Engineering

Thank you. The engine is receiving a new head gasket and turbo. It will be ready to run again in approx 4 weeks. Waiting on parts to arrive. Yavuz Unigroup Engineering

Sorry about the low quality pics. To answer your question, we're revving to around 9000rpm, and trying to stay as far below that as possible for reliability. I feel that the cams are not the best choice and the engine wants to make peak power beyond 9K. The cam timing ended up rather unusual to bring peak power rpm lower. We're just about out of adjustment as the valve will hit the piston if we advance the inlet cam any more. Yavuz Unigroup Engineering

Update After a full day at Unigroup, we stayed back at work to see what we can do about the problem. There is no time left at all to finish the car unless we have tons of luck come our way in the last minute. We've checked the tension on the head studs. We're hoping to find some of them loose below spec. No such luck. They are already tight, there isn't even the room to put more tension. This is the final straw. Sadly there's nothing left to do in time. I spoke to Julian (owner). He's not 100% sure (it was a long time ago), but thinks the head was put on re-using the old head gasket. It was due to last minute repairs and the right part was not available. So it lasted surprisingly long considering the power levels. The engine also has done a lot of hard running since. So the engine doesn't owe us anything, we owe it. So what's next? New head gasket - We still have more boost to come. We also have a nitrous system, which has never been turned on. We need the head gasket 100%. There's going to be some serious cylinder pressures. New turbo - This one makes me excited. Engines, heads and cams changed little compared to turbos in the last 5-7 years. Easiest way to make more power is running modern, more efficient turbos. I'm guessing close to 600kW at similar boost levels. New cams? - We're thinking of going back to a smaller grind. The current 280s only made marginally more power if any extra power. It's hard to compare as the cams were not the only change. The smaller cams definitely drove better, had more midrange and bottom end power. When you only have 2.6ltrs on a car this weight, you can feel every kW lost in the lower rev range. The plan is to keep the car street friendly so it can be driven. This is not a race car build. Cheers, Yavuz.

Thanks! I had a look through the list of mods in your signature. Looks impressive.

Update - This one is not going to end good… Last dyno session was stopped due to radiator neck leaking. It's all fixed. Plus we were forced spend nearly a full day on the car going over other things. We had to sort out electrical gremlins with sensor supply voltages, re-wire low oil pressure cut off, plus other things…It hasn't been a fun day. We've fitted a set of recessed tip spark plugs. These plugs are quite cold (9 heat range on NGK scale). These plugs are worth a try if you have an engine that is prone to engine knock. I've looked at the engine logs from the dyno a little closer. The exhaust manifold pressure is still lower than intake manifold pressure (29psi vs 27psi & 22psi vs 14psi). It can be beneficial to to try more overlap in cases like this. Higher pressure intake clears the chamber and forces the exhaust out. In turn you get better cylinder filling, and more power. Hence I've got extra overlap dialled in and hopeful for better results than last time. Here we go, on the dyno again, fingers crossed I just want it finished this time. Low boost runs to warm everything up is good. I can't wait to turn the boost up to see what it will do. Here comes the big run. Engine does not sound happy and the run is stopped early. We have water out of the radiator again. We're back to the original theory. The head seems like it's lifting. Good result, better power at same boost as before. 540kW at just under 30psi. We spend some time checking everything, and decide give it less boost to test the problem. Power is up everywhere on lower boost. 530kW now on 27psi (2psi less than before). On 22 psi engine is up 20kW. But we still have the problem with keeping water where it should be. In theory this engine is built to handle boost pressure similar to what most of us put in our tyres. So we have a problem somewhere… I'll see what we can do about the head lifting. The biggest problem is time available. To make matters worse, we already have a full day tomorrow. Yavuz.

I don't have any before runs but there are more dyno graphs on the next post. It would be great to get a video, but first need to get hold of a camera with a decent mic so it doesn't clip. The sound turns to mush which is half the attraction. Yavuz.

If people are enjoying reading it, then we'll do our best to keep it going. Thanks for the kind words. Yavuz.

Another quick update Problems seems to be behind us. Looking forward to the next dyno session. We'd like to have the tuning side finished off this time on the dyno. In preparation, we start going over the cam timing. This engine runs 280deg cams (more on the cams later). Lift is quite high, approx 12mm from memory. We check for piston to valve clearance. There's not much room, we don't have a lot of adjustment on the intake side. We'd like to make the peak power earlier and at the same time not give away too much from the peak figure. I'd prefer if the engine did not go much past 9,000rpm. There's 10,000 on the tacho. Ideally we'd like a custom tacho so that the 10K on the tacho reads $ and the next marker $$ and so on!!! Some experimentation with intake cam timing and we end up with again 420kW at 18-20 psi, but almost 1000rpm less for the same level of power. Looking better. Time for more boost…30psi, the engine is making approx 515kW, with the best run of 530kW. Not bad. One more run and we have water spraying in the engine bay and abort the run. Worst possibilities come to mind first; is it the head lifting?. Lucky for us, it just a cracked water neck on the radiator. We are pleased with the results but the car needs to come off the dyno again. We'd like to come back to experiment with the exhaust cam. If we run out of time, I'd be pleased to run with this power. There might be more in it and there's only one way for us to find out. Cheers, Yavuz.

Hi. Plenty of rubber under the guards. Cheers, Yavuz.

UPDATE #1 Back on the case of the misfire…We took quick look at the logs for further clues. Nothing there unfortunately. Fuel mixtures are ok, we have no reason to doubt the engine mechanicals. So quite possibly fault is with the ignition system. Also the sound and feel of this misfire tells us that it's most likely spark (ignition) related. We had new plugs, correct gaps, Mercury CDI coils and R500 CDI. Technically, with this ignition system we should have enough spark energy. So we're either looking at an installation fault or a faulty component. We are starting to run out of time and decide against further investigation. Even if we find the fault, we still need to fix/replace it and do not have any spares. Fastest way out of this problem for us is to replace the ignition system from another GTR. We need to make progress fast. We borrowed a set of spitfire coil packs from a broken RB26/30. We've wired in the Blackbox 6 channel ignitor. Everyone has their favourite ignition system. This one is my favourite. It's low cost and compact. The biggest advantage of this unit over the standard Nissan module for this application is the higher current clamp. (We have run over 50psi boost using this unit and ordinary Bosch coils). Opinions will differ here, but I prefer conventional ignition over CDI. Light load and idle is just livelier. Engines also tolerate leaner mixtures under light load with this type of ignition. CDIs also have their place. I run one after I exhaust other avenues. Engine is almost ready for another run on the dyno. Whilst we were looking for the ignition system problem we've discovered another potential problem. Have a look at the funky trace on the power supply to the ECU!!! It should be a fairly flat line. I would love the find out the source of the problem. However, time is once again the enemy. We decide to concentrate on the fix. We found a cleaner power supply else were and connected to the ecru. We checked to make sure that the problem was not present on the injector and coil power supplies. Lucky for us, no sign of the problem there. We fired the engine up with the new ignition system and electrical gremlins sorted. It sounded much better straight away and the fuel maps required fairly major changes to dial it back in. Back on the dyno, round 2…It's looking promising. First attempt, we ended up with 405kW and boost is approx 18-20 psi. Some changes to the tune, and we are now 420kW. I had a power graph to post up but can't locate it at the moment. To sum up: For peak power, we are not looking bad. However, boost arrives too late and the engine wants to rev past 9,500rpm. We decide that we should look at the cam timing before more boost to save time on tuning things twice. It's also getting late, we need to head home soon. Time to call it another day. Tommorrow: Cam timing and more tuning. Cheers, Yavuz Unigroup Engineering

Thanks!! We'll keep posting the updates.

Hi David, yes finally on the forums. Actually, I should say I'm back on the forums. Over 10 years ago I was into car forums that hard that I needed rehab to give it all up. This time it's not going to become a problem as I simply don't get the time. Cheers.

Yeah, we found that funny too. 540 reading was at Summernats. It was all in the correction factors. The reading was corrected for hot under bonnet temps plus the low barometric pressure at Canberra, as its higher than Sydney. I personally don't agree with the correction applied. It's a boosted car, so the effects of baro pressure is less the more boost you run...But I wasn't going to complain, bigger the number the better!!

Thanks! The ute is mine. I'll ask to see if Jules would swap the widebody R32 for it.