Super Long rod destroked 2.5.....
 

So, after opinions...


plan is closed deck 2.5 block
+4mm longer rod
Manley 14cc bowl pistons
Tuffrided 75mm crank
destroked to 2.3


9.1:1 compression ratio
1.8 rod ratio


been done? any good?

Mine was done using a +2mm rod on a pinned blocked, not sure on the compression but it loved meth and boost. Really liked the setup and worked well with the BW twin scroll turbo

that's the other option, a +2mm rod with mahle pistons, and a 8.3:1 comp ratio, with 1.7 rod ratio.


Im not after monty power, just reliable and nice as fast road/odd track day etc.


Blaming mikee for his mad ideas lol

It ran mostly at 1.6 bar on vpower which made about 500bhp, this was perfect for the road imho

see im not even aiming for the magic 500, id be happy with the sc42 ive got on at the minute, maybe flex fuel it and do a 20% meth for the odd track day but nothing major, just reliable and still fun, but different to what everyone else runs.

Just mirror the spec of mine dan :)

Do it do it do it :lol1:

Ur as bad as mikee!!! lol


And im good thanks tidgy, im not a sheep lol hence goin for something different

If it ain't broken, don't fix it ;)

Be interesting to see how it compares though, but i will say i told you so,,,,,, :lol1::lol1::lol1::lol1:

I don't need to compare, its an idea that im willing to try, I could simply rebuild my 2.5 but I don't wonna

Hmm, why would you destroke and end up with less displacement on purpose?

Doesn't that just mean that you get more lag for a given turbo?

it widens the power and torque band, allows better rpm, and better mpg apparently lol


the main reason I wonna try it is that with a longer rod, on a 75mm crank, the rod ratio will be better, and in turn will put less side loading on the cylinder walls.


Its something different, as banny said, hes done the +2mm version and loved it.

Any internal block clearance issues to worry about using longer rods?

there is no replacement for displacement lol

sounds a interesting build

I done the 2mm longer rod job using corrillo rods about 2 years ago. :)

there may be a small amount of machine work involved, but as the rod is longer, the degree at which it rotates is smaller, giving a better rod ratio, in turn giving a longer dwell time at TDC and less side loading onto the cylinder walls.
:thumb:

You're not changing the throw of the actual crank by doing this so the major clearance issues with crank blades won't be an issue. The rod will be getting closer to the bottom of the bore sleeve in theory, so there may be some checking needed in this area. Suspect even then it should be ok.


Interesting concept. I'll certainly watch the progress when you get started! :thumb:

You will get all the oil control ring exposed in the gudgeon pin access holes, & possibly a good bit of the 2nd ring, ok as a track engine, but a road engine oil consumption could be an issue.

Will be using a 2 litre crank, not the 2.5. also Manley make a rod suitable for an 83mm throw, so combined parts will work well ( It does on paper)

That would be mental on the sc42, the sc42 is a little angry animal as it Is already.

On mine I used a ej20 cdb I no this is regarding the ej25 block. But I used ej20 cdb ej20 crank corrillo 2m longer rods from America. Mahle short skirted 100mm pistons.
Turbo is a billet sc46 the car is so aggressive it made 473bhp and 520ftlb @ 1.6bar with more in reserve as another factor was restricting us on the day

sounds like fun!


Im hoping with the 42 on there it will work a treat, when it ran a strait 2.5 it was a lively little fecker at 430, but obviously majority of the power was low end, in destroking it will allow a wider power band, or atleast that's my hope... either way, worth a try :)

what engine size will it end up as?

2.34