What Fuel To Tune On?

[wolverine]

Ok, if the head has been skimmed it is possible that the cam gears need adjusting, bolting them back where they were might have them slightly advanced or retarded. There is adjustment on the back side of the factory gears.

This might be another avenue to run down if there is still some head scratching.

[PetroDola]

Why dont you tune it for E85, it loves high compression. Will also prove the sensor is fine.

looks like we're screwed for that in qld , unless you're prepared to custom order by the drum.

No pumps here (that ive found and ive done some research) and doesnt look like there will be for a good while yet!

Edited November 2, 2010 by PetroDola

[DaveB]

Ok, if the head has been skimmed it is possible that the cam gears need adjusting, bolting them back where they were might have them slightly advanced or retarded. There is adjustment on the back side of the factory gears.

This might be another avenue to run down if there is still some head scratching.

Thanks, *hopefully* this was ruled out by checking the static timing at idle ie. dial in 15 degrees on the ECU and the timing read 15 degrees; although the timing is read off the crank pully isn't it... hmm

[DaveB]

Just a thought: if it was the CAS sensor, and the timing is already going absolutely nuts by 4,000-5,200 RPM, should I be able to free-rev the engine to 6,000 or drive under light load to those revs without massive pinging?

Basically what I'm saying is I don't think engine load makes any difference to the CAS sensor...

Edited November 3, 2010 by DaveB

[DaveB]

Ok... an update. Replaced CAS (thanks Bob) but no change; spoke to the tuner and arranged to get the head gasket replaced rather than rebuild again; was finished this week.

At last, engine issues appear to be sorted There was another R34 with an RB25 which was rebuilt in exactly the same way, with the same pistons by the same workshop using the same machine shop etc etc and it made 280rwkw after installation of a thicker head gasket. I had my engine repaired in the same way and retuned, now making about 230rwkw with the auto and awd; not too bad a result.

I can say that, when trying to make power, it really sucks to have an auto. The same tune in a manual R34 should be at least 260-270 rwkw IMO. But, I like the way the auto drives, and I like not having to pay for clutches. Plus stall launches at ~13psi are just *awesome*. What is your 'real-life power test' Bob - was it 80-100? 80-120? I can't remember... will have to check it but it gains speed pretty swiftly now, even up there.

Tuner has raised the rev limit to 7,150 which makes 2nd gear a lot more usable; especially for overtaking on the highway... plus 380kms out of the first tank not toooo bad I guess since was only ~410kms before with much less BOOST.

So a note for future reference: if you rebuild your NEO RB25DET with CP forged pistons, you will need to measure things up very carefully; I needed a 1.8mm head gasket (I think that's what it was) instead of the usual 1.3mm to get "quench" area right. The problem with detonation appears *not* to have simply been high static compression, as I originally thought (or else I would have perhaps been justified in wanting some more in the way of compensation from the engine builder), but I believe instead it was something about the piston design where it wanted more squish/quench area to prevent something weird with the flamefront which was causing pre-ignition... sounds fuzzy and it is (in my mind anyway). This change of .5mm head gasket thickness meant a return of ignition advance and large increase in power without detonation.

BTW I am unaware of any off-the-shelf forged pistons for NEO. The only ones I have heard of are custom orders from the US which are copies of the stock cast item, but made in forged.

Edited December 19, 2010 by DaveB

[KiwiRS4T]

230awkw is not too shabby - your overtaking should be much easier! In my auto I timed it from 80 to 120 which you will easily do in 2nd gear ( I did it accelrating through 80 rather than flooring it at 80 just becasue its eaier to get it right).. I would guess you would be doing it in 3-4 seconds now. How much boost are you running now? Post up your chart in the RB25 dyno results in the forced induction section along with you list of mods. Do you have E10 available in your area? (E85 is a whole other story).

[DaveB]

230awkw is not too shabby - your overtaking should be much easier! In my auto I timed it from 80 to 120 which you will easily do in 2nd gear ( I did it accelrating through 80 rather than flooring it at 80 just becasue its eaier to get it right).. I would guess you would be doing it in 3-4 seconds now. How much boost are you running now? Post up your chart in the RB25 dyno results in the forced induction section along with you list of mods. Do you have E10 available in your area? (E85 is a whole other story).

I'm running 18 psi max boost but its dropping to about 16-17 apparently (turner told me this, apparently have hit the turbo's limit). E10 is available at a couple of servos, I will have to give it a go once I have a new fuel filter standing by... or perhaps even before. The iebc wouldn't work for the tune after I tried reducing the bleed orifice size to about 1mm so he plumbed a boost T in instead which is working up top but I'm missing the fast boost build of the electronic controller a LOT. So will swap back at some stage. Car is apparently tuned to 19+ psi so I can just setup the boost myself.

Edited December 20, 2010 by DaveB

[wolverine]

What turbo is it Dave?

[Sage222]

tune on 95. run it on 98. always safest method.

[DaveB]

What turbo is it Dave?

It's a GCG high-flowed stock '34 (the OP6 housing)

tune on 95. run it on 98. always safest method.

I wondered about that... seems that my pinging problems weren't really timing related though

[leetom]

i'm tuned on bp ultimate but can get up to 40 xtra k's on v power,dunno why, some say both are out of thew same refinery, weird eh.

ps wonder how i'd go tuned on v power?