RPM or DISPLACEMENT

[Tourniqet]

Another novice question probably.

I have a 2.4 with dgv's and a 2.5 inch exhaust and I love the high RPM's... The Tach says it goes up to around 7000 and even more. I was racing a 2003 honda civic si, and I beat him on high revs alone. I want more power from my engine, and sone solid upgrades would probably be boring it ot to a 2.6 or boring and stroking to a 2.8. I have heard that stroking the engine will significantly lower the usable RPM. I just bought an e-31 head, and plan on inspecting it, doing some polishing and maybe porting. If I can find a good machine shop I may get it milled. ANYWAY I wanted to know if you guys had experience or opinions with different motor bores. Also how hard is it to bore my block to a 2.6 or bore and stroke to a 2.8? Anyway the more I read about cars the more I feel like I am retarded.

Thanks for the info,

Allen

[Tourniqet]

oh and also I hear that better valvetrain components (light rockers, stout springs etc.) help the rpm's. So do you guys know anywhere to get the goods for an e31 head. I think they can take later l28 valves...

[Rusty1]

Sorry but I have absolutely no idea how much you can bore your L24.

What I can conform is that you are correct, stroking an engine reduces revs. There is a speed (dont ask me what that speed is) where any piston will self destruct, a longer stroke means higher piston speed at equivalent R.P.M.

Longer stroke generally increases torque.

For example a long stroke 2.6 will have more torque but rev lower than an engine with a shorter stroke but larger bore of the same capacity. But dont take my word for it, I am not an expert.

[Bambikiller240]

Rebello Racing can build an L24 out to 2.7 though you would pay big bucks to do this stuff. The E31 and E88 heads can be reworked to use the larger 280Z valves also, but again, it is pricey. IMO, going this route should only be done by professionals (Rebello, or Sunbelt, etc.) who really know L6 engines, and not attempted by do it yourselfers like us. Significant power can be made, but it's difficult to get everything done right. Mistakes can be disasterous. ($$) Experience in building these moidified engines is key.

[Victor Laury]

Wasn't there another configuration to get a larger displacement and a "square jug" (Bore = stroke)?

I can't recollect - a L24 crank in a L28 block for a destroked L26? Or something like that?

[texasz]

Why not just go with an L28 instead of trying to bore out an L24 to this size? It would probably be cheaper, easier, and yield better results especially if you go with a modified P90 or stock N42 head on the F54 block.

In fact the L28 can be bored to a 3.1 and has been done many times. This seems to be a good powerful setup.

Just a thought...

[Bambikiller240]

Originally posted by Victor Laury

Wasn't there another configuration to get a larger displacement and a "square jug" (Bore = stroke)?

I can't recollect - a L24 crank in a L28 block for a destroked L26? Or something like that?

You could be right about that Victor. I don't know the specifics on that one.

I do know that to get the L24 up to 2.7L, Rebello uses a Maxima Diesel crankshaft. The engine retains the L24's higher revving, and has different power band charecteristics than an L28.

and, Yes; it would be cheaper to just go with an L28 to get more power, but if you plan on building one out to 3.1L you will again be spending big bucks to accomplish this.

Different strokes for different folks.

[Dreco]

I will tell you that in my 3.0L rebello used a stroker crank with my L24 rods. I asked about redline of the motor, he said I could take it up 8000, but there isn't any more power after 7000.

[Bambikiller240]

Originally posted by Dreco

I will tell you that in my 3.0L rebello used a stroker crank with my L24 rods. I asked about redline of the motor, he said I could take it up 8000, but there isn't any more power after 7000.

Hi Dave:

Did they use the L24 block also, or an L28?

[JMT240KGTR]

Hi,

Copy of one of my earlier posts regarding this topic, cheers.

The L24 block can be overbored out to L28 specs, but thats about max.

As for C/R, should up it to around mid-high 9's, ie 9.5-9.7:1.

This will give an increased capacity of 2.6litre but what I like about this modification is you're keeping the short stroke, therefore the engine will rev harder.

I've helped build a motor once that didn't go the usual route of retaining the 240bore size and throwing in L28 rods and crank, this also gives 2.6 specs.

Rather we did what you intend doing and that is using a L28 bore with 240rods/crank, again 2.6 litres. We felt this engine had more power than the "popular conversion", we put this extra power down to bigger bore and higher revs (shorter stroke). Many V8s go down this route when talking "stroker vs non stroker", higher revs etc etc. It all depends on the end package and how you extract the most from it ie cam, valves, reducing weight, pulleys, ignition, g'box, diff ratio.

Mind you we also shaved the head .050", C/R was quite high, don't know what, it was never measured. Bear in mind I'm not saying this conversion would be better on the race circuit than a fully worked L28 ie L31 triple carbs, big cam etc etc!

Here's what we done;

N42 L28 block (86mm bore)

N42 head shaved .050" (bigger valves than E31)

L24 9mm rods and crank

Flat top pistons

240 SU carbs (modified needles and jets)

Camshaft provided by w'shop (not sure on specs)

280ZX elec distributor & coil

Electric fan

3 row radiator

Extractors

2.5 inch exhaust

C110 5 speed

R180 3.9 open differential

This motor was fitted in a C110 Skyline, wish it was in a Z, the Z's handling would have loved it. Evidently was involved in a smash a few years back and is gone!

Anyhow it was a quick car, and no, you won't have piston height problems, changing the pistons don't affect height only con-rods and cranks on these motors.

James

__________________

L Series Sixes; can't beat 'em!

[Dreco]

Did they use the L24 block also, or an L28?

they used an L28 F54 block. with an N42 head

[Tourniqet]

Maybe I have pushed this thing out of proportion.

I am 20 years old in college and do not have large amounts of money, large knowlege about z's, and large amounts of time. I guess my imagination ran away with this one. I bought the e-31 head for a little more punch in my 2.4, and thought larger valves was an easy swap. Also a new cam and springs are in order. The car needs new floorpans and some suspension (tie rod ends, lower ball joints, struts etc.) I put weber dgv's on it and 2.5 inch exhaust. I think I just really want this car to be my daily driver. I guess I dont have the tools, money, time, and most importantly the know how to be swaping blocks and other such things. I just want to get this head on and have a solid car.

What would you guys suggest are some of the most econmy minded upgrades that I dont have to have an engine stand for?

Thanks alot

Allen