225 long rod stroker, HELP

[whitepunkonnitro]

Point out anything I said was wrong. I will debate you all you want. Your holier than thou **** gets old.

I've disagreed with nothing you've said. All I did was lay out a few facts. I haven't really argued one way or the other.......and I will not.

Rusty, that ******* idiot was referring to me.
Ignoring the fact that I have well established credentials in everything from Top Fuel through Stock Eliminator...and everything in between..he seems to think some tinkerers on .org have some magic formula that transcends all other internal combustion principals .
I try to stay out of these discussions, but I hate to see people wasting time and energy working on combinations that are hopelessly handicapped.

 

[Killer6]

The principle reason for increasing rod length is to reduce piston side loading at high outputs, it reduces friction which frees up some power, and helps increase the lifespan
of a racing engine. Within every engine there is only so much room, & a number of popular OE's are on the short side, the slanty isn't one of them. The long rod set-up on
the slanty does provide for a much superior piston package and height, providing higher compression and a shot at a squish-zone if one mods the head for such. The rod angularity piston speed/vs burn speed dynamic is one of the reasons some OE's have done what I was investigating doing to My next slanty build, offset bores to the
crank axis. Honda, Hyundai & others have offset the bore center from the crank axis as much as 12mm, this can do things in different ways depending on the goal of the
engineers, and since they can infinitely play with cam timing programming etc. the improvement in output and efficiency has gone up accordingly.
To the OP, if You really are looking to get some output, You're going to have to stall that thing at 3K & up anyway, but the build should based on what goals You really
want to max out at. If You don't have some competent headwork done with O/S valves & effective porting, You're not looking at a peak output RPM of over 5K even w/a
sizeable cam, it will have petered out easily by then. If that's the case, a stock/stockish head means You're going to have to make the most bottom end grunt You can,
long rods won't help at all here for sure. Bumping the squeeze to at least 9.5:1 by milling would be a better way of getting the job done, and cost less at the same time.

 

[whitepunkonnitro]

The principle reason for increasing rod length is to reduce piston side loading at high outputs, it reduces friction which frees up some power, and helps increase the lifespan
of a racing engine. Within every engine there is only so much room, & a number of popular OE's are on the short side, the slanty isn't one of them. The long rod set-up on
the slanty does provide for a much superior piston package and height, providing higher compression and a shot at a squish-zone if one mods the head for such. The rod angularity piston speed/vs burn speed dynamic is one of the reasons some OE's have done what I was investigating doing to My next slanty build, offset bores to the
crank axis. Honda, Hyundai & others have offset the bore center from the crank axis as much as 12mm, this can do things in different ways depending on the goal of the
engineers, and since they can infinitely play with cam timing programming etc. the improvement in output and efficiency has gone up accordingly.
To the OP, if You really are looking to get some output, You're going to have to stall that thing at 3K & up anyway, but the build should based on what goals You really
want to max out at. If You don't have some competent headwork done with O/S valves & effective porting, You're not looking at a peak output RPM of over 5K even w/a
sizeable cam, it will have petered out easily by then. If that's the case, a stock/stockish head means You're going to have to make the most bottom end grunt You can,
long rods won't help at all here for sure. Bumping the squeeze to at least 9.5:1 by milling would be a better way of getting the job done, and cost less at the same time.

Why go through all the insanity of offset bores when you can accomplish the same thing by just reverse offsetting the wrist pins.
Which, BTW works well on all Chrysler engines, but I have found, really perks up a 225.

 

[slantracer]

65PlumCRZY just cut the deck or mill the head or both, as custom length pushrods don't cost that much and go have fun. Compression is where it is at.
whitepunkonnitro I am just a tinkerer from org. but when you are not working on that Top Fuel team , race a slant 6 event and teach us something.
Wait, that would require you to show us your 17 second or slower slant 6 that is really perked up.

 

[whitepunkonnitro]

65PlumCRZY just cut the deck or mill the head or both, as custom length pushrods don't cost that much and go have fun. Compression is where it is at.
whitepunkonnitro I am just a tinkerer from org. but when you are not working on that Top Fuel team , race a slant 6 event and teach us something.
Wait, that would require you to show us your 17 second or slower slant 6 that is really perked up.

First off. I don't work on any Top Fuel teams. My background with fuel cars is as a builder and tuner. One of the key aspects of that is bottom end geometry..cause and effect.
I wrote a series of articles in SSDI in the middle 90s on basic nitro tuning that formed a big part of the foundation for what became the norm in Nostalgia T/F
I also raced Stock Eliminator cars for a bit, and at one point ran a full half second under the IHRA I/Pure Stock record in completely legal trim.
Don't take my word for any of this..Google is your friend.
My own Slant car? Parked this year while I focus on my new shop. No time slips to show, but there have been vids posted on here that show clearly that she's a bit more potent than a 17 second car.
BTW, my car is on the ground, ready to run, and my total investment in the entire thing is less than zero dollars..I actually turned a profit of around $800 building it.
So, Mr. .org Tinkerer..back to the original topic.
Give me one single example of where any Slant, any where gained ANY performance improvement, ANY drivability or benefitted in ANY tangible way by going with a longer ******* connecting rod.
I'm betting you can't...why? Because it's physically impossible.
Prove me wrong

 

[65PlumCrzy]

Why go through all the insanity of offset bores when you can accomplish the same thing by just reverse offsetting the wrist pins.
Which, BTW works well on all Chrysler engines, but I have found, really perks up a 225.

I've been told that can be done by flipping the rod/piston 180* in the block. My biggest interest in the long rod is closing the combustion area to increase compression. The lighter piston with it also being a better Forged and not cast piston. The offset of the 2.2 will or should duplicate the offset that would be acquired when reversing a stock 225 rod combo. All this looks good when I read it, but I'm trying to put it into a build that someone has already done. The money spent on decking the block, shaving the head, modifying the pushrods, would be much more than me purchasing the 198 rotating assembly for $150. The total project with motor, I don't want to exceed 8-10k

 

[nm9stheham]

I can see the possible benefit of the longer piston dwell near the top of the compression stroke. But this is an area where only testing can show a real result. You cannot get any benefit of higher combustion pressures without piston motion too.... so less motion fights that in a way. It is all in how the pressure profile works with the piston motion to transfer energy into the crank. Simply saying it will give better results is just a theoretical idea. (And there are similar concepts of maximizing energy transfer in communications filters, believe it or not....) The new gasoline direct injection systems out offer a better potential to do this, as now the combustion pressure profile versus piston position can be optimized a lot better than with a simple 'put-all the-the fuel-at-the-beginning' system. (Which is what we do now in standard spark initiated combustion.)

And like so many things if you gain in one place, you lose in another. The piston velocity in the middle of the stroke is higher with a longer rod. And if you think about the vacuum pulled in the cylinder in the intake stroke, it is going to be delayed in building up, and will end earlier with a longer rod. That means the time for pulling in most of the intake charge will be shorter, and that means if you want the same cylinder fill, then the peak and average port velocities will be higher. Guess what? You just pushed the ports closer to choking off (going turbulent). And you'll may have to increase the cam duration a bit to compensate, so there may be detriments to that at the low end. So the long rod is gonna fight you at higher RPM's..... which is standard engine wisdom, where an undersquare engine does better at lower RPM's. Think of looong rod tractor engines. Ditto for strokers with a given head.... they don't rev as high. The flow velocities reach a terminal limit at a lower RPM.

So, if you are going for the low RPM torque, it may be the way to go. With a stock head and its flow limits, it kinda makes sense. If you are going to open up the heads for more flow and to try to go to higher RPMs, then it seems pretty clear that the long rod gonna fight that effort to some extent.

Now if you instead increase compression ratio with the standard methods of milling, that does not effect head flow velocities, etc. That CR increase is effective at all RPM ranges, and does not particularly favor high or low RPM. It also promotes better cylinder clearing at all RPM's too. It just seems like a no-brainer here....And, yes, the pushrod change is relatively trifling.

IMHO, the long rod here is a marginal help in certain circumstances, and to me would be a last thing to do if searching for the last little bit at the low end after having done a lot of other things first.

PS: OP, we were writing posts at the same time. So, I am not trying to counter your ideas, just provide the - to go with the +. I agree on seeking better CR, and the forged pistons being of benefit. Realize that forged pistons require large piston-to-bore clearances, to allow for their greater expansion. That can lower piston/bore life some, but how much is hard to say without knowing other things.

 

[65PlumCrzy]

With everyone having valid theories on what and how the setup will or won't work, does anyone have actually field test knowledge on this setup and the pros and cons for doing it?
As of right now, only the tinkerings of .org seem to have actual field test knowledge on the longer rod idea, given the idea was gotten from their page.
In the notion that it's a bad idea and won't work, other than a Hair Dryer and massive amounts of money sank into machine work, is it possible to acquire 200-250hp out of the /6? Head flow, valves, compression are all common knowledge. The problem I have most with this whole thing is some many are for the build and others are against it, but no body has given an alternative that they can show actual numbers from.
/6 owners that have nice motor builds are either hoarding what they done and don't want to be copied or are full of **** and their motors sound and look better than they run. A picture of a car in a burn out box smoking the tires of their cars doesn't mean you have a bad *** motor. I can do the same thing with bias ply tires in the middle of the street with a bone stock /6.
My build is as follows. I have a 1965 Dodge Dart GT. It will be a full interior, full exterior car. It will continue to have the 904 cable operated transmission. I already have an Offenhauser 4bbl intake and Edelrock 500 cfm carb and Hooker 3 into 1 headers. Cam has yet been decided. I already have 4.10:1 gears for a 7 1/4 rear end and also have a 3.55:1 8 1/4 rearend. Tire size will be roughly 26" not sure the size, haven't decided on a wheel. Most likely Cragar SS with 245x60r15 ET street. Like I said, I'm not hunting stupid horsepower, I've been told by both sides that 200-250hp isn't a ridiculous expensive request, just have to get the combo right.
Longer rods , IE 198 slant 6 rods, I have just acquired for $150.00. Machine work on the head including block boring will run me roughly $500.00. 2.2l pistons looked to be around $350-$450. The cam can be another $200-$250. I open this thread to get information, and you guys have delivered and I appreciate that greatly. So, if anyone is willing to school me on a good, strong, reliable setup, I'm all ears.

 

[Charrlie_S]

My build is as follows: 66 Valiant signet
Bone stock 225 short block. Just reringed and bearings. Stock cyl head with a little blending in the valve pocket, and milled to get 39cc chambers, and 340 valve springs. Old "Racer Brown" st-21 cam 520 lift 286 adv dur. stock pushrods. Offie intake, with a 390 VS Holley 4bbl. Clifford shorty headers. Electric fan and water pump. Electronic dist, with a msd 6 box. The distributor is fixed/locked at 18 degrees since I do run nitrous, so not ideal for NA. Car has a 9 1/2 edge converter (almost 4,000 stall), and 3.91 rear, with 26x7x15 slicks. At 2650 lbs race weight, the car runs 14.4's in the 1/4 mile, and 9.1's in the 1/8 mile without nitrous. The Wallace Racing calculator says the is 174hp in the 1/8, and 175hp for the 1/4. Is that real world enough for you?

PS: On nitrous it runs 7.9's in the 1/8 which says 265hp.

My total cost building the car is under $3000 including buying the car

PPS: My 66 Cuda (sold last year) with a 170 on nitrous, and 3250 lbs ran 12.90's
which is 298 hp. also had a stock short block, except for cam.

Now lets see some of the same type of info, from other posters. Put your actual numbers out there for everyone to see. I know slantracer, personally, and know what his car can do, it runs 10's in the 1/4 without power adders.

 

[slantsixdan]

I've been told that can be done by flipping the rod/piston 180* in the block.

This right here illustrates the problem of trying to build a motor based on bits and snippets of information picked up, sorta, from posts made by people who almost think they kinda remember hearing somebody say something about having read a thing in a book back around 1975 or so.

The rods go the right way round in the engine. If not, you create oiling problems for yourself.

The pistons go the right way round on the rods if you want the engine quiet. If you want to fractionally reduce friction, you can turn the pistons 180°, but then prepare for the engine to sound like it's going to think about chucking a rod until it warms up…every time.

My biggest interest in the long rod is closing the combustion area to increase compression.

Wrong tool for the job.

The money spent on decking the block, shaving the head

…is money you're going to spend anyhow, long rods or no long rods, to get the surfaces flat and the combustion chamber volume where you want it.

The total project with motor, I don't want to exceed 8-10k

Spend wisely and that's doable.

 

[slantsixdan]

With everyone having valid theories on what and how the setup will or won't work, does anyone have actually field test knowledge on this setup and the pros and cons for doing it?

Yep. Talk to Doug Dutra.

 

[Charrlie_S]

One other fact. In 1976 I was running NHRA Z/SA with a 65 valiant 100 2 dr sdn, 170 slant. It was running 16 4's on a 17.3 index. At 2677lbs that's 120 hp.

 

[65PlumCrzy]

My build is as follows: 66 Valiant signet
Bone stock 225 short block. Just reringed and bearings. Stock cyl head with a little blending in the valve pocket, and milled to get 39cc chambers, and 340 valve springs. Old "Racer Brown" st-21 cam 520 lift 286 adv dur. stock pushrods. Offie intake, with a 390 VS Holley 4bbl. Clifford shorty headers. Electric fan and water pump. Electronic dist, with a msd 6 box. The distributor is fixed/locked at 18 degrees since I do run nitrous, so not ideal for NA. Car has a 9 1/2 edge converter (almost 4,000 stall), and 3.91 rear, with 26x7x15 slicks. At 2650 lbs race weight, the car runs 14.4's in the 1/4 mile, and 9.1's in the 1/8 mile without nitrous. The Wallace Racing calculator says the is 174hp in the 1/8, and 175hp for the 1/4. Is that real world enough for you?

PS: On nitrous it runs 7.9's in the 1/8 which says 265hp.

My total cost building the car is under $3000 including buying the car

PPS: My 66 Cuda (sold last year) with a 170 on nitrous, and 3250 lbs ran 12.90's
which is 298 hp. also had a stock short block, except for cam.

Now lets see some of the same type of info, from other posters. Put your actual numbers out there for everyone to see. I know slantracer, personally, and know what his car can do, it runs 10's in the 1/4 without power adders.

Thank you. That's what I was looking for. That is a standard direction build with numbers. I greatly appreciate that.

 

[whitepunkonnitro]

This right here illustrates the problem of trying to build a motor based on bits and snippets of information picked up, sorta, from posts made by people who almost think they kinda remember hearing somebody say something about having read a thing in a book back around 1975 or so.

The rods go the right way round in the engine. If not, you create oiling problems for yourself.

The pistons go the right way round on the rods if you want the engine quiet. If you want to fractionally reduce friction, you can turn the pistons 180°, but then prepare for the engine to sound like it's going to think about chucking a rod until it warms up…every time.



Wrong tool for the job.



…is money you're going to spend anyhow, long rods or no long rods, to get the surfaces flat and the combustion chamber volume where you want it.



Spend wisely and that's doable.

You are wrong about reversing the pistons. It has nothing to do with friction and everything to do with getting the rod to lean into the direction of crank rotation sooner in the power stroke.
On some engines this particular trick will really wake up off-idle performance. It has the same exact effect as using a SHORTER connecting rod.
Any increase in noise is negligible. Every single engine I have built for myself over the last 40 years..using stock pistons..has had them reversed in the bores. I have never had a single issue associated with doing this.

 

[Killer6]

Why go through all the insanity of offset bores when you can accomplish the same thing by just reverse offsetting the wrist pins.
Which, BTW works well on all Chrysler engines, but I have found, really perks up a 225.

Look Dude, I can pull a "flip the pistons around" page out of the old Direct Connection book any day of the week, it ain't gonna provide the total effect by itself. And try
offsetting the pin on purpose the total that could be achieved offset boring and see how long those piston skirts last. Insanity? Hardly. More effort than usual? Sure. So
f#*kin' what? Pushing the edge out of what's possible from what You've got to work with ain't for Pu$$ies, otherwise, just leave it to the "experts" to tell Ya what to do.

 

[Killer6]

You are wrong about reversing the pistons. It has nothing to do with friction and everything to do with getting the rod to lean into the direction of crank rotation sooner in the power stroke.
On some engines this particular trick will really wake up off-idle performance. It has the same exact effect as using a SHORTER connecting rod.
Any increase in noise is negligible. Every single engine I have built for myself over the last 40 years..using stock pistons..has had them reversed in the bores. I have never had a single issue associated with doing this.

Hmmmm, any explanation why Chrysler and almost every other single OE mfr. bothered to offset their piston pins at all, and the wrong way at that?

 

[slantsixdan]

Hmmmm, any explanation why Chrysler and almost every other single OE mfr. bothered to offset their piston pins at all, and the wrong way at that?

You're assuming facts not in evidence. What makes you think they were offset the "wrong" way?

 

[whitepunkonnitro]

They are not offset the "wrong way", they are offset in the name of keeping the engine dead quiet in all operating conditions. The engineers did that at the sacrifice of a few crank angle degrees.
Turning them around uses that in your favor, with the possibility of a little piston slap when cold.

 

[Killer6]

LOL, the point is made. They were offset exactly for the previously stated purpose, quiet operation, it may be "negligible" to us but not consumers who can be fussy. It
moves the rod to a slightly less favorable position, and it does increase the frictional drag, flipping them undoes both of these things. My '88 ShelbyZ rattles when it's
cold because the forged Mahle slugs are more neutral and require more clearance than the cast counterparts, and of course I don't mind, I know why. You can't have
it both ways, if the pin is offset to stabilize the piston, it does so by forcing it slightly to one side which automatically generates more friction. The degree and quantitative
values aren't known & documented by anyone other than the engineers developing & testing the subject engine. Why all the pissing matches about friction vs rod angle,
when it suffices to say an improvement in output can be achieved "undoing" this feature?

 

[whitepunkonnitro]

LOL, the point is made. They were offset exactly for the previously stated purpose, quiet operation, it may be "negligible" to us but not consumers who can be fussy. It
moves the rod to a slightly less favorable position, and it does increase the frictional drag, flipping them undoes both of these things. My '88 ShelbyZ rattles when it's
cold because the forged Mahle slugs are more neutral and require more clearance than the cast counterparts, and of course I don't mind, I know why. You can't have
it both ways, if the pin is offset to stabilize the piston, it does so by forcing it slightly to one side which automatically generates more friction. The degree and quantitative
values aren't known & documented by anyone other than the engineers developing & testing the subject engine. Why all the pissing matches about friction vs rod angle,
when it suffices to say an improvement in output can be achieved "undoing" this feature?

OK, this is how I illustrated the effect of negative offset to a friend I was attempting to explain it to in my shop one day.
Take a bucket and turn it upside down on the floor.
Take a broomstick handle and place it center of the bucket.
Apply about ten pounds of effort, pushing straight down on the top of the stick and attempt to rotate the bucket on its side.
Obviously, nothing is going to happen.
Now, tilt the top of the broomstick about 5 degrees, and apply the same force...boom, the bucket flops right over.
Now, the further you tilt that broomstick, the less effort it takes to knock over the bucket.
This is exactly what is happening inside the engine in relation to piston pin offset.
The factory offset keeps the rod completely vertical for a couple of crankshaft degrees beyond TDC.
Reversing the offset has the rod leaning into the direction of crankshaft rotation at TDC, and so the initial pressure pulse is applied to rotation that much sooner.
With an engine like the slant, having such tiny workable area at the base of the combustion chamber, this effect becomes even more critical than it would be in an engine with a more square bore/stroke relationship. literally every degree counts...there just simply is not enough volume available in the chamber to effectually work the piston for the entire length of the power stroke.
Make sense?

 

[RustyRatRod]

Perfect sense. Now shut up and build us a 325 HP N/A slant. I got faith in you man. I know you can do it. You may already have.

 

[Killer6]

OK, this is how I illustrated the effect of negative offset to a friend I was attempting to explain it to in my shop one day.
Take a bucket and turn it upside down on the floor.
Take a broomstick handle and place it center of the bucket.
Apply about ten pounds of effort, pushing straight down on the top of the stick and attempt to rotate the bucket on its side.
Obviously, nothing is going to happen.
Now, tilt the top of the broomstick about 5 degrees, and apply the same force...boom, the bucket flops right over.
Now, the further you tilt that broomstick, the less effort it takes to knock over the bucket.
This is exactly what is happening inside the engine in relation to piston pin offset.
The factory offset keeps the rod completely vertical for a couple of crankshaft degrees beyond TDC.
Reversing the offset has the rod leaning into the direction of crankshaft rotation at TDC, and so the initial pressure pulse is applied to rotation that much sooner.
With an engine like the slant, having such tiny workable area at the base of the combustion chamber, this effect becomes even more critical than it would be in an engine with a more square bore/stroke relationship. literally every degree counts...there just simply is not enough volume available in the chamber to effectually work the piston for the entire length of the power stroke.
Make sense?

Why do You keep repeating Yourself as if somebody was arguing this point or claiming to not understand it?
The only possible "debate" here is which has more influence, thrust friction reduction or rod angularity early in the power stroke, by flipping the OE offset. Again, who cares?
Nobody, not You, not Dan, not Me, are going to prove anything talking about the theories and effects. The ability to test and prove the degree of effect is very difficult.
A lab at MIT might build a test engine to quantify changes and dynamic impacts throughout the cycles, wanna pay for the study? Save it,..................................
The general consensus here is, don't bother with the long rod build unless You're planning on pushing for racing RPM's, which it sounds like the OP is not.
Now go have a beer & relax!!!

 

[whitepunkonnitro]

Why do You keep repeating Yourself as if somebody was arguing this point or claiming to not understand it?
The only possible "debate" here is which has more influence, thrust friction reduction or rod angularity early in the power stroke, by flipping the OE offset. Again, who cares?
Nobody, not You, not Dan, not Me, are going to prove anything talking about the theories and effects. The ability to test and prove the degree of effect is very difficult.
A lab at MIT might build a test engine to quantify changes and dynamic impacts throughout the cycles, wanna pay for the study? Save it,..................................
The general consensus here is, don't bother with the long rod build unless You're planning on pushing for racing RPM's, which it sounds like the OP is not.
Now go have a beer & relax!!!

You're wrong about it being hard to prove. I've done it myself by measuring stall speed before and after swapping short blocks.
I did it with a 383 Roadrunner. Same top end, but a replacement short block that I reversed the pistons in..no other changes. Picked up 300+ rpm against the brake.
This all relates back to the long/short rod debate that started this whole thing. That long rod, increasing dwell time at TDC is using up precious crankshaft degrees with zero action.
I wish I had more time to devote to the Slant right now..I really love the little things, but business has to come first.
The engine currently in my car is just a mule I slapped together so that I could learn the engines basic personality.
I have one half in the works based on the later lightweight block and crank. That one I plan on doing some extensive head work on and assembling like a true race engine. Hopefully over the winter, I can get real with the thing.

 

[RustyRatRod]

Well chop chop hop sing. These cats around here may not know who you are, but I do. I know you can figure it out. Tell your hottie woman I said hay. lol

 

[whitepunkonnitro]

Well chop chop hop sing. These cats around here may not know who you are, but I do. I know you can figure it out. Tell your hottie woman I said hay. lol

I'm just another ******** hustling parts on the internet to keep from starving to death, but thanks for the thought.
The hottie got mad at me today for referring to her as "the old Battle Ax"..they get so sensitive in their old age...