306 or 306 long rod?

95WhiteVenom · Mar 2, 2006

I made a call to d.s.s. today and will shortly be starting on building a motor in the garage. I am still not sure as to what route I wish to go. I'm mostly used to the high rev. (9800-11000rpm) hondas I've worked on even though a 306 long rod will never hit those kind of rpm's.

I just wonder what one motor will have over the other and will the long rod be able to make more power easier or not?

Will it effect driveability issues either?

Any other info on these two motor will be gladly appreciated.

go-stang5.0 · Mar 2, 2006

Long rod without question. There are no down sides except it cost a bit more. Basically what they do is use a shorter piston (like on the stroker kits) and they use a longer connecting rod. The idea is that the longer the connecting rod...the better your rod ratio. The better your rod ratio the less sideloading the piston does on the cylinder wall and therefore at high rpms the stress on the block is less than a regular 306. Thats why you can spin up a long rod higher than a regular 306. And even if you dont spin it up high, there is still less stress on the block period. Basically....GO LONG ROD!

DFG 5OH · Mar 3, 2006

go-stang5.0 said:
Long rod without question. There are no down sides except it cost a bit more. Basically what they do is use a shorter piston (like on the stroker kits) and they use a longer connecting rod. The idea is that the longer the connecting rod...the better your rod ratio. The better your rod ratio the less sideloading the piston does on the cylinder wall and therefore at high rpms the stress on the block is less than a regular 306. Thats why you can spin up a long rod higher than a regular 306. And even if you dont spin it up high, there is still less stress on the block period. Basically....GO LONG ROD!

69clark · Mar 3, 2006

Definately long rod! With a long rod engine you decrease side load on the piston and you also at the same time slow the piston speed down, most notealby at TDC and BDC.

The ladies will like it too!

Grn92LX · Mar 3, 2006

If you're going to spend the money on a rotating assembly common sense says buy a 347 assembly not a 306 assembly.

If a 306 is all you want use your stock crank/rods and a nice piston.

GRGT1994 · Mar 3, 2006

Grn92LX said:
If you're going to spend the money on a rotating assembly common sense says buy a 347 assembly not a 306 assembly.

If a 306 is all you want use your stock crank/rods and a nice piston.

That's exactly what I was wondering.

final5-0 · Mar 3, 2006

I'm with Mike

I'd rather have a 347

A question about the regular vs long rod 306.

For a street motor, is it really gonna make that much difference.

Grady

blksn955.o · Mar 3, 2006

I realy dont buy the whole side load thing from the long rod...look how many 150k+ factory stock shortblocks still have cyl. cross hatching on them...if it was that big of a diff. those would be gone. MHO

I was dead set on a long rod 306...

After researching the combos that would be best for both, I went with a std. rod 306.

reason?

the long rod 306 realy starts to shine at power levels at and above 7k rpm. So if your going to use a factory 5.0 block that is just not smart as the rpm's are killer. The cam, valvetrain, intake, heads needed to support a 7k+ rpm (or even a solid 6,800 peak power making engine) are also getting into some realy $$$ parts.

yes there will be a few extra hp across the board...but at that point why have a shortblock that CAN go to 7k+ but only makes power to 6k with the avg. good h,c,i combo.

There is also some dwell time of the piston at tdc or btc with each...that was also a factor from searching on hardcore50.

For me it was just if I am not going to use it why have that setup.

Joes95GT · Mar 3, 2006

If you actually believe that long rod hype, I feel bad for you.

A 5.0 HO has a 1.697 R/S ratio. If you look at all the other "performance" V8 motors, 95% of them don't have this high of a R/S ratio. People are still building BBCs and they have R/S ratios that go into the 1.4's.

And, if anyone can explain to me what "sideloading" is, I'd be very impressed. I know what it is, but it's thrown around so casually because of DSS advertisements, that I really don't think people know what it is or what they're talking about.

PS - I've never seen or heard of a case where "sideloading" broke the block, if that makes a difference.

Joe

yellow1995Cobra · Mar 3, 2006

Get a 347, or stick a with stock shortblock and push it hard!

Rootus · Mar 3, 2006

As a practical matter, I'd probably get a 347. Well, that is, if I was not willing to pull a Jesse and get a 418 .

But I gotta admit that a properly setup long rod 306 revving to 8K would be a thing of beauty. Gear it right and it would be a screamer.

Dave

95WhiteVenom · Mar 4, 2006

Well still thinking about it but my stock shortblock will not hold up to an H/C/I swap 183k miles on it now. I won't trust the motor to get pushed that hard this late in its life. I would love to build a 306 long rod and rev it to 8k with proper cam and valvetrain and such but it will be to expensive.

The new motor will be getting a NX kit slapped on it as well. I would like to get a 347 but guys I really don't want to end up spending the money for a new balancer and flywheel cause of the 28oz. balance. Not to mention another $500 or so just to move up to a 347 and get what an extra 20hp to the wheels.

yellow1995Cobra · Mar 4, 2006

If it was me, i would just buy another stock shortblock local for 200-500. The stock shortblocks can take quiet a beating. I would never buy a complete bottom end unless it had a dart block..

Theres plenty of guys with stock shortblocks at 500rwhp and over, at that point your pushing the block anyways so why spend money on a rotating assembly when the stock stuff will work.

I looked in my local want ad, and theres 3 stock shortblocks for sale right now. One out of a 91 gt (forged pistons) for 300, 78k miles. I may pick this one up for my new project.

bimmertech · Mar 4, 2006

yellow1995Cobra said:
Theres plenty of guys with stock shortblocks at 500rwhp and over, at that point your pushing the block anyways so why spend money on a rotating assembly when the stock stuff will work.

exactamundo.

with a stock block you will never see the benefit of the longer rod due to rpm limitations.

306 or 306 long rod?

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