Project Rb31dett. The Development Of My Open Deck Rb Engine And The Quest For More Torque!

[TheGotoGuy]

check your water/meth to fuel ratios before you go spending money on overhauling your ignition system. too high meth to fuel ratio puts significant amounts of load on ignition system, more so than the AFRs would suggest, it can cause missfires that you wouldnt normally get even if you were running much richer on fuel alone. fuel to meth ratio should be no more than around 20% at any given injector duty cycle. although 12-18% i have found gives the best results with the least amount of missfires and the crispest exhaust note and throttle response. ie if you have 6x 1000cc injectors at 50% duty at 4500rpm this would give around 3000cc/min of fuel, you should only be flowing 450cc of water/meth total at this rpm, any more and you risk causing missfires, overloading coils and losing torque, it also creates a slightly blatty exhaust note that loses some of its crispness.

here is a water/meth calculator if you havnt already found one

http://www.rbracing-rsr.com/waterinjection.html#calc.

Edited February 26, 2012 by TheGotoGuy

[GTRNUR]

Thanks for your thoughts, but I was able to sort it out yesterday morning.

Changing the plugs didnt resolve the problem so I started back tracking the steps we were making while tuning. The ignition issue dissapeared when I put the exhaust cam back to where it was before we started.

It turns out that there was nothing wrong with the water/meth setup after all. Though I have still decided to change the nozzle configuration, so the tune will be less reliant on wm injection. Ive decided to use it only for intercooler and pre turbo to aid in charge cooling only. My new nozzles should hopefully arrive mid next week. With any luck before thursday night when I hope to have more dyno time.

[TheGotoGuy]

sweet, glad you got it sorted.

don't suppose you have an estimate of what lobe centers you had that caused the missfire, or sprocket settings, i have to finish up an RB25 soon and have been advised that 106-108 lobe centers is where my cams SHOULD work best on this setup according to a tuner not the cam card, i havnt done an RB cam setup before so just trying to get an idea of how far the cams can be moved in either direction before things start to cause things like miss etc?

[GTRNUR]

Follow the service manual is my recommendation. Start at 0,0 and the book dyno time to make gradual changes one cam at a time. R34 rb26 cams are different to R32/R33 and especially different to RB25 cams. This combined with my displacement increase and short rod ratio make any data I might collect useless to most other RB engine tuners.

[Marko R1]

Out of interest, what power level are targeting?

[GTRNUR]

450 kw atw at least is the goal, but im hoping for 470 ish. Im pretty confident I will achieve this at 1.6 - 1.8kg/cm as the engine responds very well to boost.

It's not all about power though. I am trying to produce a very linear power curve from the lowest possible RPM, which is why we went back to basics with the last dyno session. Tuning with the lowest boost settings and tweaking for maximum torque below 4500 will produces better results in the long run and a more fun to drive experience. We are slowly gathering more data on how the engine responds, so with any luck the next session should produce some more interesting results.

[Marko R1]

When I built my rb2630 it made 405awkw on 23psi, the torque however was massive with just shy of 1000nm of torque.

My tuner stated that the engine dynamics were similar to a 500awkw rb26...if you make 470ish, it would be the equivalent of a 650awkw rb26 which is virtually unknown territory. How many of us have achieved this one should ask?

Great build and I've watched this closely from its inception...your torque target would be 1100nm???

[GTRNUR]

I didn't really have a torque figure in mind, though if you factor in the 8000 RPM limit and the power goal then the torque will be above 1000nm for sure. More than any particular power/torque goal, I am more so trying to achieve similar goals to the Racepace RB29 vcam engine, and also the Rips stealth bomber car.

The way I see it is that Ben at Racepace achieved their results with years of experience, displacement and custom vcam and -5's. RIPS got their result with an RB30, their special head porting and a T04z. I'd like to achieve a very comparable result with a stock head, raw displacement increase and low mount GTRS's (which compare in flow to the T04z). I am also after the stock appearance that Racepace/Ben had with their setup.

Time will tell.

[Marko R1]

The stealth bomber definitely commands respect and IMO when it comes to large displacement rb's, rips are the global masters as Robbie has helped me a lot in the past.

[GTRNUR]

Spent another two hours on the dyno tonight. All in all it went pretty good. We didn't get to tune to the max boost level, tweak with the cam timing at all or run any water/meth. But have completed baseline tunes at 10lb, 18lb, and 22lb. At 22lb the engine is making the same power it was during its first dyno session with less boost and hotter air. (477 hp at the wheels).

So all in all good results so far. 30 degree ambient temps, 35 on the MDF at the intercooler, and 55 at the plenum.

With the cams set back to 0/0 again the first couple of runs at 10lb pulled 250kw and 255kw atw.

18lb made 303kw. I believe the dip in the torque curve on the lower boost setting was the turbo's still setting after shuffling as they would come onto full boost, which didn't happen on the faster ramp rate.

We did a few 5th gear 22lb runs and made about the same power as in 4th. In 4th gear as the engine seemed to load up better and the turbo's didnt shuffle. On the first attempt with a 12km/second ramp rate it tried to drive off the rollers, so the ramp rate was upped as we didn't have time (or light) to hook up more straps.

Its going to be 3-4 weeks till I can get more dyno time, as my work responsibilities won't permit more playing till then. Next dyno session will be all about tweaking with the cam gears. I am confident there is another 30kw in just the cams. Then if time permits, 25-26 lb will max out the fuel system and hopefully net close to my 450kw goal. Well thats the plan at least.

Video will be uploaded later this evening.

[Marko R1]

Have u calibrated your actuators on the gtrs's to eliminate shuffle? Also, a balance pipe running between the 2 exhaust manifolds will definitely take away all of your shuffle as this was proven on TWO06L's gtr.

I'm also interested in your fuel system setup (fuel pumps, injectors) and I apologise in advance as I'm sure you've covered this off in an earlier post.

[GTRNUR]

Have u calibrated your actuators on the gtrs's to eliminate shuffle? Also, a balance pipe running between the 2 exhaust manifolds will definitely take away all of your shuffle as this was proven on TWO06L's gtr.

I'm also interested in your fuel system setup (fuel pumps, injectors) and I apologise in advance as I'm sure you've covered this off in an earlier post.

My actuators are the 1.1bar hks type and are calibrated to lift off the wastegate seat at 15psi exactly. This equates to about 10-11psi minimum boost. I've had my twin turbo pipe split in 1/2 and welded with a baffle plate, and that has helped a lot. It used to shuffle madly at cruise speeds ~2000 rpm in 5th/6th, and the baffle fixed that. But they still get out of shape between 4000-5000 rpm if you get on the throttle at the wrong time or the wrong way. I've gotten used to it and can feel when its right to step on it, but on a dyno everything is different.

Manifolds are stock cast, match ported with ceramic internal and external coatings. Turbine housings are also ceramic coated in and out. The HKS exhaust manifold is definatly the go, but its not a road I want to entertain as I value a stock appearance more.

Im using a nismo in-tank pump and 700cc sards in a stock rail with a stock fuel pressure reg. I didn't check the duty but will check that out in the logs tomorrow. Its still pretty low from memory, but another 4 psi should have them at clost to 90%.

[Marko R1]

I also ran a split twin turbo pipe with my gtrs's and was a good mod to stop shuffle. Would it be easy enough to change the (rear?) housings on the gtrs's so that they are similar spec to the Garrett -5s?

I remember 'giant' from sau compared his stock manifolds to the hks items on his octane r32gtr and he actually lost mid range with hks manifolds, and they are prone to cracking + it doesn't look stock.

1 fuel pump with 700cc's and stock rail/fpr is just awesome...just goes to show how the high specs used when the gtr was developed

[GTRNUR]

I was reading the 26/30 R34 project thread last night and noticed someone else suggesting a T51kai was going to be used on their next engine. I was thinking exactly the same thing. Going single is the only way to eliminate the shuffle issue without taking some sort of compromise.

Yes try about the stock parts as well. I'd still be using a stock intercooler if I wasn't shooting for 450kw. The Nismo pumps are very good as well.

Video at last. Turn up your speakers.

RB315DETT Dyno session 3

http://www.youtube.com/watch?v=jo4zv9hJtqE

[BOBBYr34]

I was reading the 26/30 R34 project thread last night and noticed someone else suggesting a T51kai was going to be used on their next engine. I was thinking exactly the same thing. Going single is the only way to eliminate the shuffle issue without taking some sort of compromise.

Yes try about the stock parts as well. I'd still be using a stock intercooler if I wasn't shooting for 450kw. The Nismo pumps are very good as well.

Video at last. Turn up your speakers.

RB315DETT Dyno session 3

http://www.youtube.c...h?v=jo4zv9hJtqE

If you are going for a single turbo t51kai is the most incorrect turbo for Rb, we have done so many of them and lag is huge, there are so many other turbos that do a better job ie anything with a compressor map would be a start.

The stock cooler maxis out at 380kw

[Piggaz]

I also ran a split twin turbo pipe with my gtrs's and was a good mod to stop shuffle. Would it be easy enough to change the (rear?) housings on the gtrs's so that they are similar spec to the Garrett -5s?

-5's, -10's, 2530's, GT RS's and 2540's ALL had the same rear in a GTR application. That's housing AND wheels.

[Piggaz]

I was reading the 26/30 R34 project thread last night and noticed someone else suggesting a T51kai was going to be used on their next engine. I was thinking exactly the same thing. Going single is the only way to eliminate the shuffle issue without taking some sort of compromise.

You don't need to go single, you just need decent snails.

[GTRNUR]

You don't need to go single, you just need decent snails.

True... the GTRS's are pretty old things. Im watching that GTX28 thread with interest. A pair of those on 3+lt would be interesting. I can't help but thing the shuffle issues are always going to be there though regardless of the turbo's used, unless a HKS balance pipe is put between the two manifolds.

[Marko R1]

-5's, -10's, 2530's, GT RS's and 2540's ALL had the same rear in a GTR application. That's housing AND wheels.

Thanks for correcting me paul, 0.64 rears of course. Turbo specs are something I've never really taken much notice of.

-5s might be an option, not sure if it will take you to 450awkw though on pump 98?

[Piggaz]

True... the GTRS's are pretty old things. Im watching that GTX28 thread with interest. A pair of those on 3+lt would be interesting. I can't help but thing the shuffle issues are always going to be there though regardless of the turbo's used, unless a HKS balance pipe is put between the two manifolds.

No way. my -5's on my 'pussy' 2.8 refuses to shuffle. Any gear, any hill, any load. Thats with standard manifolds.

When I had the RS's is was just bloody stupid.

The GTX's are not a direct bolt on. I don't know about you but if I am going to hack my car up to make them fit they would wanna produce north of 500!