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Rb34 / 24U (Rb26 + 800Cc) - Project RB high deck engine (and related builds)


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I am told that everything to change the clutch has arrived, so all going well I will be able to get it booked in for the clutch swap next week.

In the meantime I have been working on the fuel system again. My powerhouse fuel hat melted another electrical bulkhead seal, so instead I've re-fitted it with an o-ring seal this time. WIth any luck this will solve the fuel smell in the car issue.

I've also decided to do away with the external surge tank, and spent the afternoon in the boot of the car trying to shoehorn a pair of 044's in there. After about 3 hours I finally got them in there and mounted. What a mission. I think that triple walbro's would have been a lot easier.

Here 's a few pics of the PHR fuel hat for those that haven't seen them.

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The R35 brake setup that I've gone with isn't exactly a typical setup. It took a bit of work to get it in there but the results are very impressive.

The front rotors are 390mm Alcons with factory R35 callipers and endless calliper adapters. The pads are PMU carbon. The bite is good cold, but when hot they are mind bogglingly good. I have to do a 100-0 brake test at some stage.

Rear rotors are DBA 380mm T3. The factory handbrake is used.

No issues with the master cylinder size. From what Ive read on the UK forums, the R34's MC is bigger than the 32/33's and is considered acceptable to use with the R35 callipers.

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Those cables through the hat look kinda small. I haven't seen a really beefy bulkhead connection that would perform as it should for this use.

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I actually tried a walbro 460 as a lift pump at one stage, and discovered they need to have the base of the pump wet in order to prime.

The mount for the fuel pump in the R34 is half way up the height of the tank, with a long pickup hose that goes down into the sump of the tank. I believe I needed around 500-550lt/hr at 75psi to meet my power goal.

There is two types of wire on the PHR fuel tank hat. Two small grade wires for connecting to the gauge sender circuit, and the other wires are much larger. Its milspec wiring with thin insulation and silver plated conductors. It will easily handle 20A.

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  • 1 month later...

Update time again.

Today was D day for testing of the engine. New clutch installed, 200lt of E85 at the ready no excuses.

After some minor issues were resolved, the 98 octane tune was completed yesterday. With 18lb we reached the knock limit at 384kw/514hp atw on the dyno dynamics AWD dyno.

Then this afternoon I drained the tank and filled with the first tank full of E85. Due to the remaining 98 in the lines and tank though the mix ended up being E60.

Trent went to work, and after resolving issues with a few intercooler hoses refusing to stay put, 457kw/612hp atw was reached. At this point the map sensor was maxed out (28lb).

Also it appeared the 1.0 housing on the 6466 had become a restriction, as power was dropping off in top end.

While I didnt reach my 500kw goal Im very happy with the result. It makes positive manifold pressure at 1800 RPM and full boost somewhere around 3200-3300, where it pulls like a mad man to redline.

I've got a fair bit of video to put together, so i'll do that in a day or so.

In the meantime, a few pictures.

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6466cea 1.0 hot side.

28lb (maxed 3 bar map sensor).

Unfortunatly the RPM signal was not hooked up during the tuning. The gear ratio torque calculation method was used on the last BP98 runs, and that made 712nm. No idea with E85, but safe to say its a lot more.

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Mmm torque.

How far do you think you'll take this? 600 hp seems like a small number for that engine.

The map sensor is maxed out. It would need a 5 bar sensor to go any further. Running at 27-28 psi leaves little sensor head room to detect a over-boost condition, allowing over boost cut to protect the engine. It was extremely sensitive to very small changes with the haltech boost control.

I also believe the head doesnt flow enough for really big power figures. It is a Tomei Genesis stage 2 head. Supposidly good for a 2.8lt at 9000 RPM... I have 600cc more than that.

Nice work, so what's next for the motor?

Thats all for this one. It has achieved its goals as a monster of a street engine. It will just be external tweaks here, and then to put some KM on it.

Development will continue with this version of spacer plate/sleeve configuration in the next two engines.

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Further to the power situation, I lowered the rev limit to 7500 RPM for this session, where it was 8100 for the last session. The power drop off is because the soft cut starts to happen at 7300. Trent wanted to rev it more because the engine certainly wanted to make more power, at least on the lower boost levels. The exhaust housing restriction only started to be evident at higher boost levels, but is also made look worse than it is by the soft cut.

I lowered the rev limit for 2 reasons. First twas that I can't think of why I would want to ever rev it that much, as below 7500 there are still two gear choices that throw you in the seat.

The second is that the Nitto H beams are using ARP2000 bolts, and I didn't want to go stressing it un-necessarilly. After all, it is a street engine still and I want it to last. At 8000 RPM this engine has the same piston acceleration speeds as an Rb26 at 10,000 RPM. And frankly most RB26's that rev like that don't tend to live very long.

The 383kw dyno sheet is of the 98 octane run. There were cleaner runs without that odd dip in the middle, but you get the general idea.

Hows it drive Ian?
We need driving feedback :)

Its MAD! Intoxicating to drive and not just from the alcohol. Its so tame to drive at low speeds, happily cruising at 1800 rpm in 6th, but its also making boost at that speed if you put your foot down. Anything over 3500 is rapid acceleration regardless of gear. Even rolling gently into the throttle in 2nd causes full traciton loss. Peak torque must be somewhere between 5000 at 6500, because the rate of rev change at this point becomes extremely quick. I've not been watching the tacho when driving it though.

I'll have to do a video at some stage of a drive. Shame there is no tracks up here and they cancelled the sprint series due to damage to the go-cart track. The only options are the training days and a go-woah event at the yearly car show. But construction of the Springmount Dragracing (Andra spec) drag strip will be finished soon. I'd like to be among the first street cars to claim a 10.

I must say that I love the smell of the E85 too, along with the note change of how the car sounds at idle now.

Back to video editing...

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Edited by GTRNUR
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Finished the video of the tuning that was completed last weekend:

I am considering options to solve the top end power drop off issue, and think that switching to an EFR 9180 could be the answer to gain that top end back not lose too much of the low end grunt.

For the moment there are a few minor changes and updates that need to be done, and then I need to get used to the car agian.

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  • Latest Posts

    • Forgot to mention that these are the before pics when I first got it!
    • Thanks @PranK for the updated member status, much appreciated! 👍🏼 Now, about those pics… Unfortunately I could only find ones that I took in the dark. I was soon to discover that underneath it wasn’t in the best shape, but it was mine and that’s all I cared about at the time 😆
    • Oh, and only having done this task yesterday, I've now driven the car ~60km since, and while it is hard to avoid placebo effect and confirmation bias, I reckon that some annoyances I had with the way the car has been behaving have improved. Which....kinda makes sense, I guess. If the bushes were really stiff and resisting rotation, they would have been contributing to the effective wheel rate. And if it was more so on one side (which it was, because one side was worse than the other) then.... you might imagine that the additional rate would be asymmetric, and potentially even different between compression and rebound. And so... the car has been twitchy at higher speeds - like freeway on ramps. It really shouldn't be. The wheel alignment is good and there are no (other) known problems elsewhere in the suspension. But at 90-100 on a long sweeping ramp, tiny steering wheel motions would make it feel like it wanted to rear steer. Quite nervous. At lower speeds it would heave about in a manner that it didn't use to. Didn't want to put power down, etc etc. Now...seems to behave better. Am going to have to concentrate on the various corners where it has exhibited weirdness, on the rare occasions when I can get a decent run at them without Methanial getting in the way in his D-Max/Ranger/LDV Van/etc.
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