pistons and connecting rods - ?'s from searching

[ScotiaDOHC]

Hello everyone!

I did some searching over the past few days in the DOHC section here (thanks dialup, I probably could have done this in an afternoon on high speed) and I wanted to get some confirmation on what I have found in my searching of various threads on here about pistons and connecting rods, as well as ask a few questions.

Connecting Rods - Small block chevy rods that are 5.7" will work in the 3.4 provided they are i-beam rods. H-beam rods will have to be machined to fit due to clearance issues. The only other alternative is a "custom" rod from Pauter.
Questions:
1) which SBC rods are a direct fit? I've seen the 327 rods and the 5.7L rods being mentioned.
2) Using these rods with stock pistons will not change compression ratio assuming everything else is stock, correct?
3) Is the Pauter part number still CHV-230-539-1448F per another thread I found?

Pistons - The only "off the shelf" pistons available for this engine are from Speed Pro which are Hypereutectic (with coated skirts per one thread). A piston from another maker (e.g. CP, JE, etc) would be considered "custom" although CP does have the measurements of the piston on file if you want a forged set.
Questions:
1) Some of the threads I found on this subject are dated, has the piston availability changed? Based on going to various 3rd party websites it has not, but I want to make sure I didn't miss something.
2) One thread said that these (Speed Pro) pistons are suitable for 95% of rebuilds out there. Is this a consensus among the forum members?

Rotating Assembly Question:
The stock crank with SBC rods (assuming they are direct fit) and Speed Pro pistons make an adequate, if not stout, bottom end for the 3.4. Agree? Disagree?
Thanks in advance.

[ScotiaDOHC]

26 reads and no comments?

I did a GM part search and from what I have found the 3.1 pushrod v6 and the 3.4 DOHC v6 use the same rods, so that helps some on the search.

[ScotiaDOHC]

it seems from other searching that the 327 and 350 share the same rods, so any SBC rod will work thats 5.7" and i-beam.

the search continues.

[WrathOfSocrus]

Not that I'm an expert on the subject but from what I have read on this site there are a few things to look out for. You need small journal sbc rods with a 2" big end bore diameter. Also the wrist pin end has a larger diameter of .927 and I believe the stock rods and pistons use a .904 pin. Lastly i believe one of the ends is too wide and has to be machined to the correct thickness to fit.

There was a thread that had all of this information but using the search feature didn't yield the proper results. I'm sure if any of this information is wrong that someone will correct it. I'll try and find the thread that had the information in it and post back.

[ScotiaDOHC]

thanks... i appreciate it... i tried searching a couple of different ways, and all I found were the general things you describe (things need machining to fit, etc) but no hard and fast numbers.

EDIT - that 2" big end... i found a spec sheet that says the size of the journals on the crank is 2". is that 2" big end after the bearings are put in? Did i misread something?

[95Grand-Am]

What are you looking to do with this engine? The stock rods are not bad and will take quite a bit before you need to step up. ARP bolts might be all you need. The pistons you are talking about should work for all but extreme builds.

[silvergtjrad]

Pardon my spam, but I have a set of scat H beam rods for sale.They already have the modifications done to use them on the crank. You need to use custom pistons with the rods, as the wrist pin size is different than stock. This will be true for any SBC 5.7" small journal rod.

$350

http://60degreev6.com/forum/f105/huge-part-out-t41059

[ScotiaDOHC]

What are you looking to do with this engine? The stock rods are not bad and will take quite a bit before you need to step up. ARP bolts might be all you need. The pistons you are talking about should work for all but extreme builds.

Hi, and thanks for responding!

I'm a tinkerer with an EE background and so the engine is going to be megasquirt powered for fuel and spark. Initially its going to be used in a "proof of concept" (i.e. get megasquirt to run it as-is) and then the next phase will be a rebuild to accomodate turbocharging. My goal is 300WHP on 93 pump gas. If it were to hit 330-350WHP I would be estatic. Based on what you say and some additional searching I have been able to do, stock rods with improved hardware and the speed pro pistons will do the job as long as my tuning is not overly agressive on the AF and timing.

Pardon my spam, but I have a set of scat H beam rods for sale.They already have the modifications done to use them on the crank. You need to use custom pistons with the rods, as the wrist pin size is different than stock. This will be true for any SBC 5.7" small journal rod.

$350
http://60degreev6.com/forum/f105/huge-part-out-t41059

Hi SilverGT, and thanks for the reply.

Right now I'm not at the rebuild phase. I am just interested in getting the motor to run with the standalone computer I've chosen. If parts were being discontinued and/or were on sale due to the holidays, I would have bought them now provided I didn't need any custom parts to go with it.

In general, I would prefer to allocate money on a machine shop for things I want/need (e.g. cleaning, line boring, cylinder boring/honing, head checking, rotation assembly balancing, etc.) and avoid having to order things "custom" as much as possible. Custom usually = $$$ and to find a performance limit I would rather blow up a set of off-the-shelf $200.00 pistons and $400.00 rods than custom hardware costing 2-3x as much.

However, if off the shelf hardware won't let me reach my goal (300+ WHP) then there isn't much point in considering it.

[Nightingale]

For your power goals i would just polish the stock rods and get some arp rod bolts. Stock rods are proven near 400whp mark in turbo applications. You will also want to get a set of forged pistons from either je,wiseco,ross,etc. If you search around on here you should be able to find the correct job number for your pistons. Granted you will spend around $700 on just pistons,but its well worth it for forced induction applications. Stock pistons or any other hypereuctetic piston under boost will fail much quicker if the engine starts detonating.

[ScotiaDOHC]

Thank you for your reply Nightingale, and thank all of you who have read this and/or have taken time to reply.

The advice is very much appreciated and now I think I have a game plan for formulating the rebuild budget.

Thanks again.

[Joseph Upson]

There is at least one stock 400 hp turbocharged 3.4L DOHC Fiero on the Fiero forum that I have read about, stock meaning original equipment parts with possibly some porting on the heads not that it needs it for boost. If you are patient and effective with tuning it can be repeated. I haven't read about a rod or crank problem yet and the piston failures all seem to be detonation related. If you are careful to avoid detonation the stock pistons can be pushed pretty far.