Thread: Opinions Stroke or Bore

I'm currently building a new engine, and have now reached the stage where a decision needs to be made regarding the bottom end.

I have currently a 92mm crank with 86mm pistons this combination in a previous build has made 255hp/205ftlb,
Quite frankly the build was terrible its a miracle it never exploded, let alone put down the figures it did.

The new build has had extensive headwork, oversized valves and will be using kelfords, an N1 runner Excessive setup and spec'd exhaust manifold.

Now with the stroker it would be undersquare I'm aware I could be limited by revs I don't want to find peak power is at 8800 for example when I'm limiting the engine to 8500,
the torque it would produce is the big plus point for this setup, this would make it much better to drive on the road, but at the same time may cause issues with the gearbox.

So I'm looking at 88mm pistons now, this would allow me to rev the engine out and make the most of the setup, whilst sacrificing some torque but making more power, being kinder to the gearbox.

So what would you choose;

1. 92mm stroke 86mm bore...

2. 86mm stroke 88mm bore....

There are positives and negatives for both options.

the latter. or 86mm stroke with 90/92mm bore, with all the other good stuff your putting into the motor.

Im not interested in sleeving a block for 90/92mm pistons so thats not an option, I can potentially get 88mm pistons for not very much money.

I would do 88x86 - its cheap, OEM reliability and make good power. Actually im slowly collecting parts to do such a build in future.

Btw. i was told that its 100% necessary to use a torque plate for SR20 for boring the block.

The machine shop I would be using have an SR torque plate, they maintain a few privateers btcc sr20s so that's not a problem.

would an 88x86 get u near that 255/205?... was the miracle that the build wasn't done properly or that the combo of the 86x92 is poor... jus looking clarity here.... how long did that motor run.... 205wtq is like small boost torq n worse boost torque isnt often as linear. so i think with proper driving that torq not ganna hurt u as much.... i like the sound a the 255/205 plus with added goodies....

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what about a 88x92?

The poor quality of the build was how it was put together.

For example they never skimmed the oil pump when they had the block done so there solution was to chop a layer out of the head gasket...



Or loosing a head bolt washer, instead of finding it just leaving it in the head, resulting in this damage when it went under the rocker arms.



And ending up here after falling down the chain side of the engine





Its a miracle it never exploded, there's plenty more I found when I stripped it down.

88x86 would yield more power and less torque than the stroker setup.

There is a 45cc difference between the two setups the stroker having the larger cc

suggestion why not get itb's or centre feed plenum from lance hayward he make quality components

id get a stock ve an bolt a gtir setup on, or even something better.. probably cost similar and last longer and probably have more fun .. thats my .02