Have a few questions about rod length, I have dont mass amounts of reading online. Now my understanding is.... clearance issues mainly between short and long. Now this is just my logical thinking.. But wouldnt a shorter rod be a snappier motor? compared to a longer stroke? Maybe theres no difference , Any input is greatly appreciated, Ive read so many different things I think i made things worse on myself lol

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"IT IS WHAT IT IS"

Short stroke engines tend to rev quicker and are capable of higher rpm. Stroker engines produce more torque at a lower rpm and thus do not need to be reved so hard to produce peak torque and peak hp at lower rpm. The exotic hill climb engines are utilize a dry sump which allows the engine to rev more freely as the crank is not splashing through oil. I am sure there are other secrets to making a stroker quick revving. I am sure it involves $$$.

So hope that answers your question.

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Water Cooled Consortium, Chairman of the Build (Former AC purist)

Lots of debates on this subject,maybe some of these motor guys who is a lot smarter than me can explain it better,but if I'm thinking right a few things make the longer rod better for more power because the rod angle is less and has less friction.the long rod also gives it more leverage sorta to help with creating better torque.the longer rod slows the piston down at tdc and helps create more combustion pressure and is faster going through bdc to help the intake valves draw more fuel.I THINK,LOL. Not sure but this is what I'm thinking. Chad

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NOW GAS IT!!!!!

longer rods allow the piston to have more dwell time at TDC and BDC which will allow more time for intake fuel air mixture to fill the cylinder at BDC. at TDC more dwell time means better quench and a more complete and efficient combustion. this doesnt mean that you can throw in a an extremely long connecting rod because there is always a trade off. the greater the rod ratio the higher the engine SHOULD rev and there is also less side load on the pistons. a shorter rod will increase piston side load but SHOULD be easier to drive as the power will come in sooner. there are those that will disagree. long rods increase port velocity so smaller not so exotic heads will produce better power. can talk shop all day but bottom line is you need to ask yourself what you want out of an engine, how much money, gears,weight, and driving style. trust me its a learning experience. one that im still wrestling lol

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ask no questions and you'll get no lies

lol....I understand the short rod putting more stress on things, compared to the long. But the long rod, requires the higher rpm to make the power. that the short is right off the bat. correct? So get a size inbetween and call it a day? lol also, doesnt the long rod require extra clearancing

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"IT IS WHAT IT IS"

I've read on here before that a 5.7 rod engine comes on better than a 5.5 rod engine. Hopefully like gasman said some of.the engine builder will help clear it up. I might have been able to a little if I would of spent more time tuning mine. But....I didn't.

While a shorter rod does put more side load on the pistons,the side effects in my opinion are minimal at best. A short rod engine will be more responsive on the bottom end compared to a long rod engine with everything else being the same. Many big time engine builders say the connecting rod has one purpose,It connects the piston to the crank. Rod length will make no difference in clearancing unless you run a huge stroke with a short rod and you might have clearance issues between the crank and piston skirt at BDC.

Makes sense. Any opinions on the scat kits like on dansperformance? would be in the super street section i believe

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"IT IS WHAT IT IS"

aaron and ken summed it the best i think, at least to my understanding.
i know a lot of race car (non vw) guys that like to use the longest rod possible but most of those engines stay "flat footed" the majority of the time, and as far as clearance, the main issue with longer rods and strokes is that after a certain point it starts makeing the engine wider causing issues with fitment in the engine compartment but on a buggy we generaly dont have a problem with that and like aaron said too short of a rod causes issues with piston skirt to crank clearance. for woods riding i like the shorter rod engines personally

a rough/simple example i like and while exagerated/not exact is with all the same parts staying the same except for rod length a
5.4 rod will make peak torque at 2000, 5.5 at 3000, 5.6 at 4000, 5.7 at 5000, etc........

go here
http://actionimport.com/
they have a rod ratio calculator in the tech section

try to keep it above 1.60 and the side load on the piston shouldnt be to bad from what ive understood

heres a few examples of some petty common stroke and rod combos
82 stroke with a 5.394 (stock) rod has a 1.671 ratio
86 stroke with a 5.5 rod has a 1.624 ratio
90 stroke with a 5.7 rod has a 1.609 ratio

heres a pretty good read with a section on rod length
http://www.aircooled.net/vw-performance-engines/

and another
http://www.chircoestore.com/catalog/smf ... pic=4936.0

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Just Stand On It!!!!

Chris

X4 I like to run 1.6 to 1.8. Most V8 run there . A 2276 and stock rod is 1.67 and a 2387 and 5.7 is 1.68. I run a 2387 and 5.7 rod Drews ported S/E heads 10.3 comp. FK 43 cam 44 carbs it runs good in the woods buggy and races good in the A-arm buggy. There is no long rod or short rod its the write rod for the stroke. That you can get and fit.

Longer vs shorter the piston speed is the same. Dwell time is WAY different. Peak horsepower is very similar with the longer rod winning on peak power. The MAIN difference is shorter rods make the power lower in the rpm range, the longer rods make the same power higher up in the rpm range. There are tricks you can do to tweak each set up to optimize the way each motor runs.
Building a buggy motor can be done either way, it depends on how you drive it and what you want it to do for you. If you were racing 1/4 mile on asphalt for example, you would want the longest rod that's a reasonable ratio to the crank you have. I personally like shorter rods for a buggy motor with dual carbs because the torque comes in sooner in the power band. You don't have to rev the motor as much (Unless you want to) wich in turn makes it last longer. High RPMS wears out a VW motor faster than the side loads caused from short rods.
If you like to run around in your buggy at full throttle all the time, you should use long rods.
These are my experiences.

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Buy the best and cry once.

I have a very good understanding of things now, Thanks guys . With H- beams the side load isnt so much of a worry is it? Atleast it makes ya feel a little better about it?

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"IT IS WHAT IT IS"

The side load on the piston is the same weather it's an "H" beam or an "I" beam. The strength of the rod is different between the two. Connecting rods need to be the strongest thing in the motor. Don't cut corners here. H beam is the only way to go if you can afford it.

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Buy the best and cry once.

H beams are already figured in the budget. Im selling off half my toys so i can build this new motor. Sad yet excited and the same time.

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"IT IS WHAT IT IS"

not trying to hijack here but since this is about "rods" is there any brand better than the other for the h beams, ive heard a few folks say some brands are better and need less "clearance" work than other brands and then some folks say they are all basically the same??????

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Just Stand On It!!!!

Chris

In all of my reading, The h-beam chevy journal is the least amount of clearancing. But besides that, I havent found anything saying one h-beam requires less or more than another? Good question If there is a lesser one I think ill be checking it out lol

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"IT IS WHAT IT IS"

Unless you are buying Carrillo or Pauter,they are all the same. You can't beat CB performance for price and quality. Scat H-beams are available with a 3/8" bolt that would require a touch more clearancing.

i read somewhere that an h beam rod is not a must have unless ur gonna turn 10000 rpms and that an i beam is better for force fed engines i think i read this on aircooled.net ive been running scat i beams chevy lournal with 3/8 arp 2000 bolts i think the last set i bought they were 150 shipped to my door

i cant seem to find where i read it, but im thinking that it was eagle rods that are supposed to require less clearancing due to the cap profile or something of the sort, but then again it could have just been more interweb jibberish

also ive heard cb, empi, and bugpack rods are all the same aka come from the same place

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Just Stand On It!!!!

Chris

So you saying instead of spending the $$$$ on cb h beams i should just get empi?? lol

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"IT IS WHAT IT IS"

the cb's are like $30 Cheaper than empi's

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"IT IS WHAT IT IS"

No matter which ones you get ,make sure you get the ARP 2000 bolts

definantly not my advice lol i was saying thats what ive "heard"

i have actually passed a deal by on a crank and rods before just beaause the rods were empi

i was hoping there was some truth to the "rumor" that some brands didnt require as much clearancing as others even if they did cost a little

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Just Stand On It!!!!

Chris

says they come with arp 2000 so i should be good to go.

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"IT IS WHAT IT IS"

call me crazy but cb, empi eagle scat (with 5/16" bolts) bugpack and a few others are the same rod with different logos on them. They all come from the same place. Thats what I've noticed anyway.

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Maybe you should chug on over to mamby pamby land....