Beefing up the 3RB's low end

[SubMeister]

I just tried the 3RB manual and GTB manual (both MY07) back to back. Just love the induction growl of the 3RB (reminds me of my old Audi V6 2.8 ) but prefer the punchiness of the GTB. My ass-o-meter also says the GTB had a meatier low/mid end while I had to rev the 3RB a bit more to get the same ass-o-meter reading. So I looked up the engine output specs on the net, and voila there's 600 rpm gap between the two.

This is what I mean: the 3RB hp peaks at 6,600 rpm and GTB's at 6,000 (only a 4kw diff). And the 3RB's max torque comes in at 3,600 rpm, with GTB's at 3,000. GTB also has 4KW and 40nm more torque. In the GTB the fun starts 600 rpm earlier.

My question: Are there any mods you can do to the 3RB that will make the torque/hp kick in earlier...and ideally improve fuel economy?

For example on my Suzuki GSX 1400, I installed a Yoshimura tri oval slip on and a PowerCommander, and had the thing dyno'd for a custom map. I got 10% more hp, a earlier flatter torque curve, fuel economy up 10% and the throttle response was just snappier all around. Didn't have to mess with cams, compression ratios, full system exhausts, etc.

Is there an equivalent treatment for the 3RB? I did some searching on this forum and post below is the closest thing I could find. Have things moved on since then??

Thanks in advance



=======================

Current Fuel Economy
by MH3.0R » Sat Jul 12, 2008 9:50 pm

Recently had another V-Tune after having an exhaust mod done (Quad Tips) and while no real improvement was provided by the mufflers only mod, I have achieved a new record for economy in my 3.0R while driving a mix of city/freeway. I achieved 8.6 L/100Kms (conservative driving, nothin over 3000 rpm) and was so surprised to see it on the dial that I took a photo of it. There after, I took to driving normally (the odd squirt to 6500 rpm) and are consistently achieving 9.2 to 9.6 for the same city/freeway mix.

For those of you citing poor economy, consider the Power Flush of the Injectors, a dyno tune (mine was done by STi Melbourne) and maybe check some other things like the oil, oil filter, air filter etc.

Kind Regards,

Mark.
Logic is like Fingerprints - we all have them, but they are all different!
MY05 Liberty 3.0R 5AT White Sedan (His)
MY11 Impreza 2.0 4AT Sky Blue Hatch (Hers)

WHAT'S TURBO LAG?

MH3.0R

Posts: 940
Joined: Sat Apr 12, 2008 9:29 am
Location: Melbourne, Vic
Real name: Mark

[MH3.0R]

For the ultimate performance mod for my 3.0R Lib has got to be this one:

viewtopic.php?f=10&t=12969#p176570

Plus, you get the full history of mods. Your 6MT is as sweet as can be, so no need to work on that.

[kiks]

Why are you focussing on peak torque and power RPM's? They're irrelevant. The 3.0RB has more area under the curve, and is a happy little potter at 1000rpm in any gear. The GT needs to be wringed to an inch of its life to mumbo. The pure fact it has another 2 cyls firing makes it so much smoother to drive at low rpm, and makes about 20% more power at idle alone...

If you want to get rid of some of the doughyness, remove the 3rd cat, replace the first two cats with a better product. Job done, huge improvement.

Food for thought:

had more torque and power at 3000rpm than a stock sti liberty did at 6000rpm. The 6cyl is a sweet thing when you let it breathe properly, and those stock cats choke it hard.

[SubMeister]

kiks mate I only posted the peak figures to compare the diff in when the power/torque kick in between the two mills. I'm 100% with you on wanting to fatten up the curve area say below 3,000 rpm as that's where most of my daily driving is done. Doughy is a good way describe the stock bottom. Anyway, it sounds like an ECU reflash + the double cat setup should do the trick...how much would some good cats cost, and what make do you recommend? That's a nice engine bay you've got there - what else have you done to it?

If you want to get rid of some of the doughyness, remove the 3rd cat, replace the first two cats with a better product. Job done, huge improvement.

Thanks MH3.0R but this is just a bit over the top for me. Might just get a Rex if I had to spend that much!

For the ultimate performance mod for my 3.0R Lib has got to be this one:
viewtopic.php?f=10&t=12969#p176570

[kiks]

Any off the shelf 100cpi unit should do fine. Same as it would on a 2.5. The 3rd cat replaced by a 2:1 merge collector (off the wall item on any exhaust shop). The rest of the stock exhaust is fine, if a little bit choked but its nothing major.

Power discussions between the two stock cars is kind of irrational, the 6cyl is so much better off boost than the 2.5, where most of the driving is that Its largely a non issue. But the 2.5 is certainly easier to mod for bulk ponies.

As for pic, not my engine. Brothers old donk, now sold off and in an impreza chassis. But it was amazing to compare it to a 3.0RB and how well it behaved off boost compared to the stock restrictive cats/exhaust/intake on a 3rb.

[BJ]

Have a look at this post for tuning. There are other similar posts about Edward's tuning if you search a bit.
viewtopic.php?f=16&t=14432

[west_minist]

If you want power in earlier, fuel eco will go down slightly to get more power like around 2800+?

It becomes a fine balance between throttle and when to add fuel, since the car been design to run eco up to 3800+rpm and for emissions.