Rpm Limit

[ynhrgt]

I don't think there is a section dedicated specifically to engines directly, unless I'm blind so I thought I might as well ask here. Regarding stroker kits that are available for the RB26, which obviously increase the stroke / torque of the RB26 to 2.8L.

My question is why not just bore out the RB26 to an RB28, instead of increasing stroke, reducing the maximum rpm an rb26 can rev to. Increasing stroke is nice, as it obviously adds to the amount of torque that can be generated, but are there any actual big bore kits available?

On a side note, how high can a RB30/26 hybrid rev to? Assuming the engine has countless dollars into it.

Edited May 24, 2006 by ynhrgt

[stolen_s15]

From my (limited) understanding boring the rb26 block is not the best option, because there is not a huge amount to be gained before block integrity is compromised. I've never heard of a big bore kit before, but ya never know. Try the search function.

If you have countless dollars anything is possible.

[Beer Baron]

you cant bore far enough to get 2.8 with a standard stroke. well not without eating into the water galleries and reducing strength.

a 2.8 stroker kit is considered to be a nice compromise, more torque, but still plenty of rev capability.

[Quinny]

Just use an RB30 block and crank. There was another thread about this, it is a very common conversion with VL commodores to use the RB30 bottom end with RB26 top end.

The RB30 bottom end will be way cheaper than a 2.8 stroker kit, and you get 3.0L instead of 2.8L.

As stated, there is not enough metal on the bores to allow you to bore a 2.6 to 2.8.

In regards to the rev limit, if the engine has been built correctly (i.e. good rods & pistons, balanced, intake etc), then you could get them to rev to 8000 or 9000rpm+ easily. The sky is the limit.

Put it this way, the Trick & Mansweto Capri drag car makes 1000rwhp, naturally aspirated at 9000rpm from a 600ci big block V8. You can get any engine to rev high if you have a good engine builder and plenty of money

Edited May 24, 2006 by Quinny

[r33_racer]

I think with std harmonic balancer...around 7-7500 is about the safe limit...what im curious to know is how far could the rb30/25/26 hybrid rev to with an aftermarket balancer like the ati or ross ones? 8,9,10....?

Sorry in advanced if ive hijacked the thread.

[R31Nismoid]

you can rev a 26 higher than 7500 on a stock balancer. 8000 no worries

[paulr33]

with a bigger discplacement (rb30det style) you shouldnt need to rev to 9 grand. its peak power will probably drop off past 6 grand. i think most econo style rb30det's can rev to 7 at the most. thats enough anyway, why rev past that? it wont make more power

the lower the rev limit the better i say

[Oblivion]

what i was thinking....there is no point in reving the rb30hybrid higher cause its power is lower down...the 2.7 stroker would rev better then a 2.8 too. but a 2.8 would technically have more torque. If you want it to rev stay with a smaller stroke...maybe even just stroke it a touch and put in 40thou oversize pistons etc.

[r33_racer]

sorry r31Nismoid i meant safe limit for rb30 hybrid...not straight out rb26.

paulr33

But do you know for sure that the power will drop off that dramatically? If you have a head with some fairly wild cams in it, port and polished, solid lifters and the right sized turbo say 35/40 with .82/1.06 rear that power will not be made in excess after 6 grand. Im curious to know, cause the 25/30 were building will be limited to 7k, however if extra rpm can be used it means you can hang onto a gear longer so long as the power is still climbing, fair enough if it isnt then no need to rev it past that point.

My understanding is that stroking increases torque, whilst oversize boring increase the engines revviness. Weve stroked it by using the 3 litre block, but weve increased bore by oversizing it. weve gone both ways, so i would think its possible to get some extra rpm outta the engine, so long as the harmonics are addressed and its gonna make power past that 6k point.

[Craved]

BU5TER is revving past 8,000 on his RB26/30 with aftermarket balancer

[r33_racer]

okedoke..so it is possible. I was hoping to hear something like that. But whether the gains of extra rpm justify the cost of an aftermarket dampner?? Like i said, was just curious. Sorry for hijacking.

[paulr33]

right that makes sense, but why rev much higher?

more rpm means more stress, more heat, more friction and power loss

if you have two engines

one rev to 7000rpm

one rev to 9000rpm

the one that revs to 7000 would likely have less fatigue and stress on it, at least it would seem that way, and also depending on gear ratios, could have a better average power.

[r33_racer]

Yep, i understand the reliability side, the lower the revs the less strain on everything. But if it comes to the crunch and were really desperate i know my we will want the extra 1k or so to help stretch out the gears, so long as its feasable.

[2443]

From NISSAN engineer... each parts have diffrent rev for RB26 because that problem is for the cost. The crankshaft rev is about 7,800 rpm. Standard harmonic Balancer is same. The standard valve spring is about 8,300 rpm. But the valve guide is not strong enough for such rev. If you make the best clearance for the valve guide, that engine is no problem 8,300 rpm. When NISSAN raced with RB26 that the short distance race was 8,300 rpm rev (It was sometimes 8,800 rpm rev thouht). The Long distance race was 7,500 rpm rev.