i have narrowed to a choice of 2 srp pistons for the 385 one weighs 467 grams for a 5.7"rod,the other is a lightweight 405 gram for a 6"rod with an oil rail support.the car will see 85% street time,so my question is,is there a problem with longevity in these lightweight pistons?it obviously can't hurt performance to lose over a pound from the pistons alone?
also will the 6" rods help or hurt in that department?from what i understand,they might boost torque a marginal bit and offer a mechanical advantage?(as explained by a friend)
Eric

Disclaimer: Not an expert

It's my understanding that there are pros and cons to each, but probably more pros for the longer rod. Chief among them is lighter pistons. The piston is lighter because the pin is moved higher up on the piston to accomodate the extra length of the rod. The piston still has the material where it is needed for strength - it is just a smaller piston (top to bottom) and therefore it is lighter. The lighter pistons make the engine easier to balance. On a 383 this puts the oil ring in the pin hole, which evidently isn't a big deal.

If you had identical street engines, one with 5.7 rods and one with 6.0's, could you tell the difference? I doubt it! (see disclaimer)

I used a set of wiseco forged 2vr flat tops in my 5.7" rod 388. 454 grams each, all for about $440 including pins, spirolocks, and a set of hastings plasma-moly rings. The quality appears to be top notch, and the price is hard to beat.
I seriously doubt you'll ever notice a difference between a 5.7" and 6" rod engine...especially on a mostly street car. A 6" rod may require more clearancing of the block than a 5.7" rod, and IMO the oil ring supports needed on a 6" rod piston just add something else to go wrong. JMO.

I agree with the other posts...on an 85% street ride you will never notice the difference in power from rod length. I would recomend the 5.7 rod piston. You don't have to worry about the oil ring support. Also, while it's true a 6" rod puts (slightly) less side load on the engine, the shorter piston and skirt will be more likely to rock in the bore which will lessen longevity. You might get into cam clearance issues with the 6" rod as well depending on brand.

I used to run 540 gram TRW 400 forged replacement pistons with 5.565 rods and hit the strip every week. Never had a problem.

Having said all that, I did go 6" rod on my latest engine but it sees 85% strip duty. If I was looking for 100,000 miles I would have gone with the 5.7 rod set up.

i wouldnt worry about SRP pistons "rocking in the bore" SRP generally runs tight on clearances.

I like the 6" rod because the piston is lighter.

Dragfab is correct, you'll never notice the difference between 6" vs 5.7" but the reduction in side load will help the rings last longer and wear in the cylinder will be reduced. JE/SRP pistons are high quality pieces and only require .005" clearance vs .0065-.007 for TRW's.

Anytime you can reduce reciprocating weight it is a good thing. I would shy away from racing type pistons with short compression heighth for a street only ride. The oil ring that high on the pin will cause problems in the long haul.

One question I didn't ask is what is the differece in cost (if any)? 440 grams is a pretty doggone light piston anyway (my 6" rod 4.155" bore pistons weigh 440 grams).

Also, here is some very interesting reading on the topic of rod length for anyone interested.

Rod length article (http://members.tripod.com/racerjoe/classic_faq/all_classic/rod_length.html)

JE/SRP has a website with their catalog, I'm not sure if the prices are listed. The lighter pistons are shorter but they do make hollow dome pistons that are extremely light. I understand that eagle H-beam rods(6") are profiled for stroker motors and will not interfere with the cam.
I am a firm believer in building the bottom end beyond it's intended use because we all know that speed and power are addictive. Saying that,it would surprise you how many stock (forged) combos are out there making huge power.

thanks a ton to everyone for your info and opinions on this subject!special thanks to greg for the article,good reading for anyone building a stroker.to answer your question greg,the diff in price was $47 at jegs.i was thinking that because the .040 block now has cast pistons graemlins/sad.gif that due to the different expansion properties and honing requirements of cast and forged pistons,i will probably have to take the bore out to .060.i didn't want to but that would make the pro tru -20cc dished pistons another option.did i mention the 64cc topline vortec heads?
hey travis,are you running iron heads with those flattops?hurry up and get that thing on the road so i can find out if detonation is gonna be a problem! :D
Eric

Yep, iron heads...10.3-1, but I do have a pretty large cam. Hopefully I'll get the guy to start on the new tranny tomorrow so it will be ready by this weekend.