I compared the differences between 1.6 rockers and 1.5 rockers in DD2000 and the power numbers were the same. I used Pro 200 with 2.08" valves. And a comp roller XR274-12 cam. HP only went up one at 6000 rpm.

 

Well, I would think it would increase power throughout , the more rpm though probably the more HP. IT increases the lift of the cam (not sure if that is totally correct), or if it's actually like the lift at the valve.

For me, my cam is 477/480 lift where with 1.6s it will be 509/512.

 

Your looking at the mod in the wrong way......

example:

Lift with 1.5

.540"

Lift with 1.6

.576"

There is a definate advantage in the higher ratio... dont you think?

Unless your heads do you no justice by not flowing any signifigant more amount of air with the gained lift.

Or, You do not have the proper induction system to allow your heads to flow the extra air that you allowed your heads to flow by increasing total valve lift...

Or, You flow the air, induction is great... but your clogging the works with a factory choke it out exhaust system...

A mod is something you do as an addition to your setup to make your current setup more worthwhile...

People dont (rarely) install CNC cylinder heads on their engines, and leave the stock camshaft in place.... or leave the rusted up factory exhaust system on the car....

Food for thought....

 

But they'll slap a 150 shot of "NOS" onto their VTEC and wait for it to blow

but those heads benefit from high lift cams, so I'd say 1.6s would be a great way to go.

 

Heres an image of the DD2000 comparison. No power is gained until 6000 rpm. And i don't want to rev a 3.75" stroke motor up that high. I have the ProTopline 200 cc heads that flow really nice.

 

forget something, lol.

anways, what's wrong with revvin to only 6k, I don't see how the stroke has too much to do with it... I would think the condition and quality of the bottom end is a little more important.

 

Reving a 3.75" stroke crank up to 6500 rpm is not a good idea with a cast and stock rods. Plus my 383 won't make power that high, with peak HP before 5500 rpm. So there really is no point unlesss i ran a bigger cam, which i don't want to do.

 

Lift has nothing to do with the Power or Torque curve... The LSA and duration of your camshaft play a major role in the manners of the engine. Lift is (as a whole) your engines ability to breath in 0.000" ......

If lift mattered as much as LSA and duration...... You would never hear of people running 1.5 on the Exhaust and 1.6 on the intake.

WE would all be squeazing as much lift as possible......

 

All i am asking as a general rule of thumb does 1.6 ratio rockers produce any power gains over running 1.5 rockers? Because DD2000 is showing for my combo that they do not increase power until 6000 rpm, which is way out of the power band.

 

DAng, look at those numbers,wish I had a roller cam with those heads, ahh well, the one I have will do for now.

 

I am getting at 1.6 roller rockers should be a mod you do when building up an engine, just like adding a K&N airfilter... You just do it, because it needs to be done...

I dont worry about how much HP i will loose if i take off my 1.6 rr... It needed to be done. So i did it... Just like splayed - forged 4 bolt mains..... i didnt gain any power out of those.. It needed to be done... so it was done...

You cant justify every mod by how big the power #'s will be... You just do it because its part of building up an engine

 

I see something wrong with your logic there. 4 bolt mains are for insurance purposes not done for HP, but a mod such as buying new rockers is to increase HP, correct? So, I think he has a valid question...

I'd say get them, it will only help with those great flowing heads.

 

Too each there own... Yes Roller Rockers will increase HP....
My point simply is.. Dont install them Expecting the worlds largest increase... unless you have the mods too support that increase..

 

There's why increasing the valve lift by way of rocker ratio didn't increase the HP.

Torque = number of fuel molecules burned per engine revolution. HP = torque per time; i.e. how fast does teh engine produce this torque, or at what RPM does the torque exist. Therefore, HP = flow, i.e. number of gasoline molecules per time, which of course requires air molecules per th esame unit time, which is another way of saying "flow", as in cubic feet (of air molecules) per minute.

You engine is a pump. Think of all the pieces of the induction system as neing like a string of sections of garden hose. OK, you got your carb... it's 50' of 3/8" hose. You got your intake... 25' of ½" hose. Then the valves..... 10' of ¾" hose. Then the heads... 10' more of ¾" hose. Then the exhaust.... 50' of ½" hose.

OK, now you take the valves, and you up the size to 1". What just happened to the overall flow of the system?
.
.
.
.
.
.
.
.
.
.
Nothing.

That's what you're seeing by analyzing that combo with DD2k.

Now take those same heads, put a Super Victor intake on it, a 850 CFM carb, and 1-7/8" headers, and run it again. You should see a bit more difference. Because when you do that, all of a sudden the limit to the engine's flow is the valve lift!!!! As long as something else is limiting the flow, it doesn't matter how big you make the other parts, the limiting thing is still going to be the one that governs flow, and therefore HP.

 

Now your getting out of the league of the question and topic at hand....

In your sig... I assumed you had a mildly modded engine.... Now your using a computer program throwing in crazy parts....

If you add roller rockers to a stroked 383 with CNC ported heads and high flow exhaust.... High flow CNC ported intake....

of course you are going to see different results, than if you installed them on a lightly modded v-8.....

You cant compare the 2.... 1 is going to benefit more than the other.... Bottom line....

 

No I'm not. He has a patently mismatched combo if he just sticks those heads and that cam in the motor in his sig: giant heads, massive cam, 305-sized carb & exhaust. I merely picked a combo that those heads and cam would be a better match for, and invited him to see that by installing those heads and cam he had moved his flow limit from the valves to something else.... the carb and headers in this case.... and that no further improvements in teh heads and cam (including higher lift) would affect the total engine flow and HP.

 

Isnt that what i was saying above........?????



I can see Opinions werent wanted here...... everyone already had there own..... L8R.....

 

OK, then please explain to us in your opinion why increasing his rocker ratio (valve lift) didn't produce an increase in HP (flow).

 

 

I dont believe that is the question at hand....

I dont care why a computerised engine didnt produce more power with imaginary 1.6 rr on a virtual dyno....


That isnt the point... I was repling with my opinion.... Do you flame everyone who doesnt answer to your specifications...

Think about it Buddy , this thread is arguing over a $270 part... versus thousands for an engine.... little bit strange to me....


maybe if we had the imaginary flow chart on the virtual heads...

we would definatly see that there is no signifigant flow difference between the lift that 1.5 and 1.6 provides.

Maybe this thread should have been HP bang for the buck...

and i would have replied TNT Wet kit....

 

Then again.... what do i know.... I purchased all the parts for my engine all at once.... and i chose competition cams chromemoly 1.6 rockers 7/16 stud.... for strength and durabilty... not the power increase....

 

No, I don't flame anybody ever, too much work. I let them do it to themselves.
What stock cam are you talking about?

Can you please explain why, in your opinion, his HP (flow) was not increased by the rocker ratio (lift) change?

Those simulator programs aren't my favorite way of doing business either; for that matter, neither is spending cubic giga$$$ at some shop: I build my own. But the simulators, while their absolute numbers are sometimes ludicrous, can point out in a big hurry where an engine can be improved, and where it can't. In this case, it clearly show that he's maxed out his flow in the heads and valves (since the flow didn't go up by enlarging those), and the logical person would therefore conclude that the engine's bottleneck must lie elsewhere.

 

Ok, nobody has answered the question yet! I know this combo may not be the best right now but i can always add better parts latter. But why go through all the trouble running 1.6 rockers if there is no gain? All that is doing is stressing the valvetrain more then necessary.

 

for 1 i said mildly modified...

and i did answer your question....

Where is the flow chart on the heads.....?

What is your point anyway....?

 

If your using stamped steel rockers.. I disagree...

if ratio is your concern and longevity is your goal.... 1.5 rollers is the key to stress relief

 

Here is the flowdata:

All i'm asking how much power is usually found using 1.6 rockers over 1.5's? Is it worth stressing the valvetrain? What about valve to piston problems?

 

ME:

The reason they don't increase your HP, is because in the configuration listed in your sig (which I assume is what you're plugging into the simulator) the valve lift isn't the limit to the engine's flow. It doesn't matter how low the restriction in that place is, other restrictions are determining how many air molecules can squeeze through that motor. Look at the pump & hose analogy, that's the simplest way I know to compare how your engine behaves to something you can easily watch in action. HP is directly proportional to total engine flow, period. If you max out one portion of it to where some other part is flowing at its absolute *****-to-the-wall capacity, then further increases in that already maxed-out part won't increase the total flow.

Go ahead and do the DD simulation on a combo using the same heads and cam, but all the surrounding parts larger, and examine the change the rockers produce; I'd bet that it will be almost exactly a 6.666% increase (1.6 divided by 1.5). Direct, linear, one-to-one relationship of port size (valve lift) to flow; because the other parts of the engine won't be preventing further flow from occurring.

Or, like you say, why increase the stress on the valve train if it produces no improvement in performance. But, one could also ask, why put 400-sized heads on a motor when you're going to leave a 305-sized carb and exhaust on it. Match your components better: either reduce the heads to something within the same realm as the rest of the engine, or bring the rest of the engine up into the same league as the heads.

Rocker ratio increases absolutely will increase engine HP, if and only if the rest of the induction and exhaust components of the engine support that increased flow. They absolutely will not increase flow if something else in teh engine is limiting the flow. And if they don't increase the flow, then they're the wrong place to spend moeny; you need to be spending it where it does increase flow.

 

What is going to make your decision for you..... 30hp ?

You cant calculate the power freed up from the friction loss changing over to Rollers.... You cant calculate the stress relived in your valvetrain changing over to rollers...

People do it because it has been proven over and over again... wether it makes power or not.... Its a proven mod...

Make your own decision... there is a ton of info in this thread... a ton of Guru's opinion's to base your decision off of.....

 

Ok thanks.

 

I truly believe in my own opinion... Roller rockers are stronger and more durable than stamped steel... and they reduce friction and reciprocating weight....

To me that is worth more than 10hp....

2 cents.....

 

Here is a hotter setup with still very minimal power gain.

 

Another thing about rocker ratio, and therefore valve lift...

It increases the lift at all points on the valve motion curve, not just the peak. So when the lift would have been .200" with 1.5s, it's .213" with 1.6s; when it would have been .300" with 1.5s, it's .320" with 1.6s; etc. etc. The valves actually spend alot more of their total open lifetime at those intermediate lifts than they do at their max lift. So it's meaningless to compare just the peak lift numbers. And, even if the peak flattens out a little bit, it's "area under the curve" that counts. Take calculus: that area is the integral of the valve position function.

But, it's all in the combo. If the rest of the combo is really free-flowing, the rocker ratio is a big payoff; butif it's not, the payoff is reduced, or non-existent. The simulator tells you that but not in so many words. You have to make the changes yourself in the packages you simulate to find out where the bottleneck is, i.e. where a (hopefulley) small $$$ change will make a big flow change. HP / $. Sometimes it's rockers, sometimes it's the cam itself, sometimes it's something else.

 

.570" = .608" on a 1.6 not .610

 

Yeah i just realized if forgot about that. I have taken calculus infact i have taken 4 calc classes. Next semester i am taking differential equations. Being a Mechanical engineering student means you have to take a lot of math!

I guess i might get some 1.6 ratio then.

 

That was only a guestimate, or a quick estimate.

 

What would the lift be on a 465 lift cam with 1.6's ? Thanks.

 

The rule of thumb is that 1.6 rockers will increase the lift by .030" over 1.5 rockers. Thus your new lift, from .465, would be around .495.

Be careful doing this with stock type heads. Without machining the spring seats and valve guides, they can only accomodate lifts in the .45x to .46x range.

 

YA have to take DD2000 with a grain of salt.

It only shows you trends of what you can expect by changing/
adjustiing differnt parts.

Increasing the rocker ratio , if it is going to show a
power increase (it may not) it will show this increase at the upper end of the power band, usually at the cost of a little low end power. This is typical.

On mild build ups with mild cams(dual pattern) (maybe too mild) you will often see a nice gain when you swap on a 1.6 rocker especially on the intake side.
Because it acts a lot like putting in a little bigger cam.
BUT... On a more highly tuned motor with a better "right cam" in the first place you may/do often actually see no power gain at all.

Generaly it is the overall increased valve action and increased area under the flow lift curve that results in the increase.

Engines in cars accelerating do not operate at peak horsepower
all the time. they have to accelerate through the power band.
High ratio rockers may increase high end peak hp a bit but may not make your car actually accelerate faster, because it lost as much low end power as it gained in top end.
So it all depends.

DD2000 does not take into account the effect on the mechanics of the valve train or valvefloat at all.
swapping to 1.6 rockers can have a big often unexpected effect here. usually the valve float rpm limit is lowered unless the springs are changed to compensate.
Doesn't always work out as sweet as the hot rod mags would have you believe.

There is way more power to be found in swapping in a different cam grind then swapping rockers, even roller rockers.
But Roller rockers are pretty impressive looking and easier to change than a cam and lifter set.

You can make way more than 400 horsepwer on a 350 with .450" lift hyd cam and stamped stock 1.5 rockers. *With the right .450" lift cam*. Getting the seat duration ( valve events) and mid lift valve action that the motor actually wants to make power is way more important to making power on a street motor.
Won't even go into the effect on valve guide wear that high lift
has. A 415 hp motor with stamped steel stock rockers beats a
350/375hp motor with 1.6 roller rockers ever time.
Usually for a lot less too.

 

So are you saying i can get away with running 1.5 ratio stamped rockers? Or just roller tip rockers?

 

They are about half the price, are they as good?

 

I gotta jump in here.....

DD2000 has directions..... READ THEM!!!!!!!

If you read the section that explains what type of cam you're using, you'll see that they basically say that the "Roller" cam option is primarily calculated by using a SOLID roller cam. If you use a beefy hyd roller cam (like the one you're using) then you should use JUST the solid cam option, or even the hyd. cam option if the cam isn't even close to radical (like the LT1 cam). If you're half way between a "radical" and a "street" cam, then you should use both options, then average the two.

This may seem like an inconvenience, but you have to remember that DD2000 is a $40 program, not a $400 program.

Secondly..... why are you similating this engine with a single plane intake? If you're basing it on the impressive low RPM torque numbers even with a single plain... read above.

DD2000 is a descent program..... but it's a $40 program. It has it's pitfalls, and you HAVE to read the instructions to learn how to make it as accurate as possible. Although I do have to say it is 100 times better than the first version.

And as F-BIRD'88 said..... it's not gonna show you a huge gain with 1.6 rockers for two reasons.....
1) It's a cheap program
2) The gains of using 1.6 rockers aren't as high as the magazines would like you to think.

I would recommend Comp Cams Magnum rockers. They're a basic stamp design with a roller tip. They last forever + a day, they're MUCH more accurate than stamped rockers, and they aren't real expensive. Just remember that FULL roller rockers DO NOT last as long. The needle bearings in the fulcrum wear out @ 40-50K miles of NORMAL use, not including 1/4 mile blasts.

 

The XR-274R-12 is a solid mechanical roller camshaft, a HR cam would be a hydraulic roller!!

 

the cam specs for anyone who wanted to know them. kus i donterecall anyone stating them.

 

what i got in dd2000 with his setup

 

and what i got with his setup with an 850cfm carb like somebody suggested. which is a must. a 600cfm carb on a 383 is a joke. and defnitly the 1 5/8 headers are too small for this motor.
like they said. dd isnt exact. but the bigger carb made gains all thru. which is obvious it will especially on ur motor.

i didnt do it with the rockers simply because its a matter of what you have. kus an lt4 hotcam works well wit 1.6 rockers. but other cams may not. i guess it all boils down to what u have.
its like everyone says in every single thread. u gotta match parts. so i wouldnt be worrying at rockers right now. id be worrying about your carb and exhaust

 

I know it may not be optimal but i already have a carb and exhaust, i can always upgrade later. The thing that i don't have is rockers, thats why i'm asking.

 

its about do u want to squeeze every last bit of horsepower out of your engine?

 

OK.... my bad. I don't deal with Comp Cams a lot so I'm not familiar with their part number sequence. I've mainly used Crane since 4 out of the 5 cams I've ever swapped have been solid cams.

FWIW, I'd still average the numbers between "Solid" and "Roller" lifters. IMO, it's better to under-estimate with a program like that, than it is to think that you're gonna get every last HP that program says.

Taking that into consideration, that looks like one hell of a combo you got going. Let me know when you get it done so I can buy a few shares in Micky Thompson.