Was planning to build a 383 holden using 6 inch rods (already purchased) but after doing more research have been told that these will wear out the bore a lot quicker than the 5.7 rod setup. For a reliable motor would i be better off trading them for a set of 5.7s??? Have been told will loose a few hp but wear less, is this true?

you will not make any more power with the 6" rod, wives tales im afraid...for reasons i cant be bothered explaining, unless you want to turn 7000+ its of no real benefit, and the whole bore side loading thing doesnt really matter at the kinds of engine speeds we are likely to see.

Im not sure how the angels will help anyway, but i pray everyday that my engine dont explode, and it hasnt yet, so maybe its working?

since your deck height limited, id be more concerned about keeping the gudgeon out of the oil ring more than any pressing need for a particular rod length.

Id even consider chev 400 rods if there is an off the shelf piston to suit.

the idea of a connecting rod, is to attach a piston to a crank, nothing more complicated unless youre into a whole r+d program to find thousandths of seconds.

Find the right piston AND rod, not one without the other.

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Read Everywhere on the net and Visit sites that build these engines.there is plenty of good articles on the subject ,as peoples ideas are different and its your needs that your looking at.Ive done all that and was amazed at the stuff I read and learned.To me it depends on the rest of the engine components for matching.street engines arent big revvers so no need to go too far...just my opinion..cheers

Jim in adelaide

quote:

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Originally posted by petaus
you can make more (very high rpm, 7000+)*power with the longer rod, (if everything is 100% right, for us mere rodders/street machiners its not worth having a compromised piston)*

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a long rod does spend more time at TDC and accelerates away SLOWER, which in fact signals the port LESS at most engine speeds useful to a street car, and some race applications.

It also accelerates away from BDC FASTER, which would seem to cut off inertia filling of the cylinder earlier and hurt power in the lower rpms.

This is a desirable trait in very HIGH rpm applications using poor cylinder heads because it draws on the port at a SLOWER speed and can aid in the airflow NOT going sonic.

Prostock, which is a cubic inch limited aspirated class (400 cubes here, 500 i think in the states) are turning between 9 and 10,000rpm,they use a short (by conventional standard) rod (less than 5.7")...

Seems to buck the trend, and if anyone would want the "benefit" of a long rod, it would be Prostock...

Im not doubting a long/short rod CAN be of benefit, i just dont dont think its here where us "little people" play...

At any rate Petaus, the piston is probably more important in a short deck (compared to a chev) Holden block, im glad we agree on that at least :)

Cheers.
*Just so everyone is clear the bolded additions to Petaus quote are mine.

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Edited by user Thursday, 25 June 2009 7:34:52 PM(UTC)  | Reason: Not specified