To 30/26 Or Keep The 26?

[NYTSKY]

miss my 26 noise.

the 30 just doesnt sound the same.

Agreed. My 25 sounded like a snappy F1 engine compared to my 30.

[BLITZ-26]

I had this same debarcle

In the end I decided to stay with the 26 they rev harder everything bolts together and it cost a lot less to build

So I ended up with oversized pistons that bring it up to 2.7 litre and brand the comp up to a nice 9.1 on e85 should be a weapon

The point is if yours aint broke dont throw 10 or 7k at it to fix it its alreay making good power and response as u said work on the setup if u want more or made striping the shell for less weight, light weight wheels better brakes and suspension there is a lot more to a track car than outright power

And if you get serious you might be not allowed in some events for changing the L size from factory ?? I am not sure someone else mabe can conform this

[Piggaz]

"Rev harder"

For a joe blow,average guy, why do you want to spin the engine to the moon and back? It just won't last.

Stroker or RB 30 all the way. More twist ... EVERYWHERE!

[Mick_o]

Still don't get this "rev harder" philosophy? What do extra revs get you anyways? It doesnt necessarily increase your power range and im sure that an engine that makes power sooner and doesn't need to be spun as hard would probably be more reliable in the long run. Especially in track circumstances!

[r32-25t]

Still don't get this "rev harder" philosophy? What do extra revs get you anyways? It doesnt necessarily increase your power range and im sure that an engine that makes power sooner and doesn't need to be spun as hard would probably be more reliable in the long run. Especially in track circumstances!

but but you get to tell your mates you rev your engine to 10,000rpm and that makes you cool

[Mick_o]

Haha! 10,000rpm and 13nm of torque

[XGTRX]

26s sound better than 30s always have.

Dont get me wrong you cant beat a 30 for low down torque but you dont need to spin a 26 to 10k to make power.

They are more than capable under 7500 around a track and a built motor is more than happy there.

[black bnr32]

more revs = less torque required for equal power = smaller components = lighter weight = faster

more revs = faster

[r32-25t]

more revs = less torque required for equal power = smaller components = lighter weight = faster

more revs = faster

less torque= less motive force to move said wieght forward and ends up slower

[Mick_o]

Smaller components and more revs = faster?

Pistons in a dragsters are probably the size of small saucepans.

Guess they don't rev or go fast then?

more revs = less torque required for equal power = smaller components = lighter weight = faster

more revs = faster

[Lithium]

more revs = less torque required for equal power = smaller components = lighter weight = faster

more revs = faster

Less torque = more revs required for equal power

More revs = best way (short of detonation) to drastically increase stresses on an otherwise equivalent engine

Weight = RB26 and RB30 have the same bore. Increased recipocation within a time frame will add more drag on the crank than a slightly longer rod

Faster = There is probably a reason that most race classes are broken into displacement categories, the reason Nissan put an RB26 as opposed to bigger into a GTR was because of such restrictions.

Sound... I'll just leave this here:

[SimonR32]

Nothing wrong with a RB26 and unless you want well over 500rwkw. Under that a 2.6L will pretty much match a 3.0L at 4500rpm and above which means it will be just as fast at the track or the drags because that's the rev range that is used.

Obviously the extra torque off "power" of a 3.0L will be nicer to drive on the street but will also use more fuel.

I know at the track I can cap the revs of my RB26 to 6000rpm and still be on boost and have plenty of torque in the next gear, it's actually still brutally quick and I have the option of an extra 2500rpm on tap if required.

[Frosty]

RB34 and you will re-rotate the world when you put your foot into it..

[fatz]

Nothing wrong with a RB26 and unless you want well over 500rwkw. Under that a 2.6L will pretty much match a 3.0L at 4500rpm and above which means it will be just as fast at the track or the drags because that's the rev range that is used.

Obviously the extra torque off "power" of a 3.0L will be nicer to drive on the street but will also use more fuel.

I know at the track I can cap the revs of my RB26 to 6000rpm and still be on boost and have plenty of torque in the next gear, it's actually still brutally quick and I have the option of an extra 2500rpm on tap if required.

On a tight circuit... Ya na

Ability to use a higher gear and get the power down makes a massive difference

[Roy]

"Rev harder"

For a joe blow,average guy, why do you want to spin the engine to the moon and back? It just won't last.

Stroker or RB 30 all the way. More twist ... EVERYWHERE!

Something I have noticed , and it was easy for me as only running a 2L RB20 with TD06 I gave away displacement and sometimes power to cars but give or take had the same gearing.

You come out of a corner at a certain speed...not a certain rev. So if cars both come out of a corner at 70km/h and a car with an RB26 makes its power from 4,500rpm to 8,500rpm and the RB30 makes its from 4,000rpm to 7,500rpm....well my money is on the RB26 being quicker irrespective of torque etc etc Especially if it can hang on to a gear longer. Thats assuming you have simply thrown in an RB30 and running same wheels and gears. If you cant rev the RB30 as hard as you can the RB26 then I dont think you can automatically say the RB

If you go RB30 and drop a gear ratio and you can use the torque to push you along then so be it.

And for those talking about reving an engine to the moon.

A) its fun. WAAAAY more fun then changing gears at 6,000rpm like you do in a say a typical V8. Hell my Cossie has a limiter at 7,200rpm and I really miss the extra 1600rpm my RB20 gave me.

B) you got a shorter stroke or if you are lucky and have a narrower bore and lighter piston then revs dont hurt an engine more then a bigger engine pulling less revs. At the end of the day its the metallurgy of the crank, rods and pistons and how you oil and cool the thing. I agree that you want to make as much power with as few revs and boost as you can make....but do the numbers on stroke, piston speeds and rod lengths etc before saying revs are bad.

[r32-25t]

Something I have noticed , and it was easy for me as only running a 2L RB20 with TD06 I gave away displacement and sometimes power to cars but give or take had the same gearing.

You come out of a corner at a certain speed...not a certain rev. So if cars both come out of a corner at 70km/h and a car with an RB26 makes its power from 4,500rpm to 8,500rpm and the RB30 makes its from 4,000rpm to 7,500rpm....well my money is on the RB26 being quicker irrespective of torque etc etc Especially if it can hang on to a gear longer. Thats assuming you have simply thrown in an RB30 and running same wheels and gears. If you cant rev the RB30 as hard as you can the RB26 then I dont think you can automatically say the RB

How about we change this scenario slightly

Cause in your case they will both on song.

How about we talk a out a 60km/h corner

Both cars come out at 3,500rpm the 26 gets hosed because it hasn't got to torque to pull it out like the 30 does.

Or the 26 drops down a gear now it's revving at 6,000 but it now so on edge it's nervous and twitchy coming out if the corner and you can't get full throttle because of it, the 30 still hoses it because it doesn't need to drop a gear is nice and smooth thru the corner and uses its torque to just simply drive away

And if someone give me the "it's fine the attesa will settle the car" line, then you haven't driven a Gtr close enough to the edge

[Roy]

I will say it. The AWD does make it easier to grab a lower gear and rag on it out of exits. But I understand your point.

I am yet to see where having an RB30 makes the car measurably quicker on the circuit. I would be very interested to see someone that kept the same turbos and head but only changed to an RB30 bottom end whether they would be quicker at the track...I think the lowst revs I pull at the track is Sandown turn 4 and I am still at 4,200rpm in 3rd....so easily able to grab 2nd but your point about drivability means I try to hold 3rd.

If the RB30 is still ahead of the 26 at 4,750rpm when the show is all happening with boost in its guts and can hold on to 7,800rpm then I guess the RB30 is the better option.

[Lithium]

I am yet to see where having an RB30 makes the car measurably quicker on the circuit. I would be very interested to see someone that kept the same turbos and head but only changed to an RB30 bottom end whether they would be quicker at the track...I think the lowst revs I pull at the track is Sandown turn 4 and I am still at 4,200rpm in 3rd....so easily able to grab 2nd but your point about drivability means I try to hold 3rd.

I am sure there will be a case - problem is most of the time if someone does that much of an upgrade they change a variety of things and there will be teething issues, or BIG jumps in performance... depending on how things go.

For what it's worth, people (especially with turbocharged motors) have gone to lengths to improve torque and reduce lag as a means to drop lap times since people started hunting lap times - instead of specifically looking for RB30 vs 26 vs whatever lap times... just look for people who have gone quicker by improving response, torque, or even power.

Also - where is the compromise with going for an RB30? I have never seen a dyno plot where the power on the RB30 is lower than the power on an RB26/whatever where everything else is equal. The RB30 dyno plot MAY drop off more than the RB26 one, relative to it's peak... but I have never seen it fall below the RB26 equivalent at any point in the utilized rev range. That is not even taking into account the thing you can't see on a dyno, how long it takes to "come alive" when you step on the throttle.

In regards to the piston speeds- or more importantly, piston acceleration... lets ponder it.

Firstly - I'm not going to do PROPER airflow or engine cycle maths because CBF and the main point I am trying to get at should be easier to follow this way...

Lets say a 2.6litre @ 7000rpm = 2.6 x 7000 = 18200litres/min

Now 18200 litres/min / 3.0 = 6066rpm to move the same amount of air to access the same power level.

Now to get the average piston speed -

RB26: 7000rpm x 73.7 / 1000 (convert to metres) / 60 (convert to m/s) = 8.6m/s

RB30: 6066rpm x 85.0 / 1000 (convert to metres) / 60 (convert to m/s) = 8.6m/s - surprise surprise!!

Now here is the clincher... if you were going to look at it in an overly simplified manner you would go "Sweet... that's the same piston velocity, we're good - short stroke ftw because it's smaller and it moves the same air, right?"

OK... now consider this:

RB26: 7000 / 60 (revs/s) *2 (piston direction changes a second) = 233 stop/starts per second

RB30: 6066 / 60 (revs/s) *2 (piston direction changes a second) = 202 stop/starts per second

So, the RB30 and the RB26 have exactly the same piston speed to move the same amount of air - yet the RB26 has to stop and start 31 times a second MORE than the RB30. If you think about it, while the average speed is the same - the only way that it is possible for the RB20 to have the same average speed despite coming to a completes stop 31 times a second is to slow down faster to a complete stop, then accelerate harder to a HIGHER peak velocity and then repeat the cycle.... 233 times a second. It is not possible to travel the same distance stopping 15% more times within the same period of time without having to work harder to achieve that. The same power with less displacement = working harder.

In case of train spotters, yes I know those numbers are not all going to be exact, or in some cases technically completely incorrect - but in terms of illustrating my point if you changed them to exact final numbers the relative differences should be relatively on par.

[XGTRX]

good scenario but wrong theory.

W = mad; you will be creating the stresses on an rb30 at lower rpm due to the higher forces generated by the extra weight and stroke length of the rotating assembly per revolution. They will wear out the same as a 26 revving much higher.

rb26 has less rotating mass, less acceleration due to the stroke length being shorter, and travels less distance.

As for your theory of stop start stresses the only difference is weight, the more weight the more forces on the rotating assembly because of the inertia resisting the change in direction, and again the same stresses happens at a much lower rpm in a 30 than a 26.

Thats why a built and full balanced rb26 on or off boost spins up at a faster rate and can safely rev higher/ much higher

And dont think an rb30 on song is going to be a tame beast, both will require throttle control coming out of slow corners.

A 30 is easier to drive but its no better or worse than a 26..... With all things being equal you wont kill a built 26 changing gears at 8k but you will kill a 30, and a 30 will be a torque monster at 4500 where a 26 will just be coming on song(with -5s that is), , because they are different and need to be driven differently.

and did I mention 26s sound better????

[r32-25t]

A car with more torque will always be easier to drive and therefore faster (all racers know smooth is fast) and it you can argue it till your blue in the face fact is fact. Horsepower sells cars, torque wins races!

As for sounding better, that is not even worth responding to