Benefits of higher seat pressures

[karolko]

I am looking for some info and opinions on what what seat and full open springs pressures everyone runs on their stage motors.

I specifically am running a stage II motor, 224/224 cam, roughly 600 lift and GN1 Heads and a belt drive.

What are there any major pros and cons to running higher seat pressures. I was thinking about running in the area of 300lbs on the seat.

Any opinions and info would be appreciated.

Lastly, what brand of springs would you reccomend.

Adrian

 

[turbobitt]

This is really too many variables to have a cookie-cutter answer. The cams aggressiveness, valve train weight, and intended RPM really dictate the spring required to do the job. The next challenge would be to get the selected spring package to fit within the constraints of the head.
As general statement, when running really high spring loads you need to be conscious of the wear on the cam bearings, roller lifters, and rocker gear as well as oil control to the mentioned components. Valve train stiffness also need to be considered when selecting a spring. Remember that you need to fit the appropriate pushrod to open against the loads your asking it to do.
One thing that I found from researching this subject is that you would surprised on what you can get away with if the springs are properly set up. I been experimenting with running my springs really close to coil bind per my engine builders recommendation and find that the springs last longer and are more stable. Another benefit is that they require less opening load compared to what most would run.
AG

 

[norbs]

Valve guide and valve seat wear is something you may also want to consider as the spring pressure goes up....

 

[turbobitt]

I am looking for some info and opinions on what what seat and full open springs pressures everyone runs on their stage motors.

I specifically am running a stage II motor, 224/224 cam, roughly 600 lift and GN1 Heads and a belt drive.

What are there any major pros and cons to running higher seat pressures. I was thinking about running in the area of 300lbs on the seat.

Any opinions and info would be appreciated.

Lastly, what brand of springs would you reccomend.

Adrian

To more directly answer this question I'm running about 280 seat and 650 open and using Isky tool room springs. I put 1200 miles on these without any degradation in load. I have these set up .055 from coil bind but could get even closer without issue. I found these to be a good comprimise for the street/strip driving I do with this engine.
Allan G.

 

[norbs]

I am running some comp cams springs which are about 235 seat and 590 open, double spring I wish I had the part number but they came included with the cam..

 

[Nick Micale]

.............I specifically am running a stage II motor, 224/224 cam, roughly 600 lift and GN1 Heads and a belt drive.

What are there any major pros and cons to running higher seat pressures. I was thinking about running in the area of 300lbs on the seat.

Adrian

Years ago when we started building high HP turbo engines we use 300+# seat pressures, but found that much pressure is not needed, even for engines running up to 9000 RPM.

We now use about 250#'s on the seat, and find that will do fine in the high RPM and HP engines.

My personal engine is now at 190#'s on the seat and the normal shift point is close to 7000 RPM, and have seen it higher in some cases. My cam is a little more aggressive than what you have, and the lift is about .640".

The downside of higher spring pressure is unnecessary load and wear on the valve train and valve seats, and more HP drain on the engine, not to mention less life of the springs.

We also have found that the Isky springs are an excellent choice.

 

[bison]

The cams that will make the most power with the least amount of overlap require a lot more spring pressure. Look at duration @.200" and look at the duration near opening. 228*@.065" with 145@ .200" will not need anywhere near the amount of spring or pushrod 228@.065"with 152@.200" will need. The one with more duration at .200 has a similar opening but the ramp in is way more aggressive. What this means is there is a lot more potential for cylinder filling/emptying if the rest of the combo is up to the task. Like Al mentioned the spring requirements, valvetrain weight, intended rpm, pushrod selection, etc are even more critical. The cost to install an aggressive one is quite a bit more expensive. You don't break records or set standards by running average "stuff".

 

[ULOSE2A6]

Would there be an advantage to keeping the spring pressures lower by running a hydraulic roller as opposed to the solid roller? Or would that not allow the RPM's needs in some combos?

 

[turbobitt]

Would there be an advantage to keeping the spring pressures lower by running a hydraulic roller as opposed to the solid roller? Or would that not allow the RPM's needs in some combos?

Don't let the hydraulic rollers fool you. Most if not all of the various hydraulic profiles Bison and I have analyzed are more aggressive than most solid rollers. They still require the appropriate spring.
AG

 

[bison]

Would there be an advantage to keeping the spring pressures lower by running a hydraulic roller as opposed to the solid roller? Or would that not allow the RPM's needs in some combos?

The aggressive hyd profiles the way most guys run them need the high spring pressures more because of the aggressiveness than the rpm.

 

[sweetv6]

see that

http://www.racingsprings.com/Movie-HPValveSpringTesting10KRPM

and that

http://www.racingsprings.com/Movie-HPValveSpringTesting10KRPM

 

[karolko]

just bringing this back from the dead,

what size pushrods are you guys using when running around the 250lbs seat springs?

Also I am a little unsure what this thing will make power to, rpm wise. Do any of you guys have an idea of what a 224/224 solid roller cam with a Precision 7675 will make power until? I am thinking 6-6500rpm.

Thanks a lot in advance.
Sweetv6, those videos are very neat, and It really showed me how unequal the coil compresses and how much the valve actually wobbles. Thankfully I won't be running my motor up to 8-10k rpm,. I wonder what springs do at lower rpm (6000 rpm) compared to 9000rpm.

Adrian

 

[turbobitt]

just bringing this back from the dead,

what size pushrods are you guys using when running around the 250lbs seat springs?

Also I am a little unsure what this thing will make power to, rpm wise. Do any of you guys have an idea of what a 224/224 solid roller cam with a Precision 7675 will make power until? I am thinking 6-6500rpm.

Thanks a lot in advance.
Sweetv6, those videos are very neat, and It really showed me how unequal the coil compresses and how much the valve actually wobbles. Thankfully I won't be running my motor up to 8-10k rpm,. I wonder what springs do at lower rpm (6000 rpm) compared to 9000rpm.

Adrian

For pushrods, I'm running Trend 3/8 to 7/16 double tapper(forgot the wall thickness - maybe .180)

Allan G.

 

[karolko]

Allan, or anyone for that matter, what is the maximum size you can fit into Champion GN1 Heads?

What are the downside to running larger than needed pushrods, other than valve-train weight?

How does one go about figuring out what diameter and wall thickness one needs?


Thanks a lot for the help everyone, I am learning a lot.

Adrian

 

[bison]

Allan, or anyone for that matter, what is the maximum size you can fit into Champion GN1 Heads?

What are the downside to running larger than needed pushrods, other than valve-train weight?

How does one go about figuring out what diameter and wall thickness one needs?

Thanks a lot for the help everyone, I am learning a lot.

Adrian

You may need to machine the pushrod holes for clearance. I've had to do it even with 5/16 pushrods in some instances. Downsides are clearance issues. Over the nose pressure, ramp, pushrod length and rpm will determine the pushrod minimum requirements.

 

[karolko]

can you quickly explain over the nose pressure, is that valve seat pressure when valves are closed? or open?

Adrian

 

[bison]

can you quickly explain over the nose pressure, is that valve seat pressure when valves are closed? or open?

Adrian

It's the pressure at max lift.

 

[GARY HARVEY]

240 lbs. seat @ 90% bind will get the job done unless you need to be killing flies with a 5 lb. hammer.
A few other things can be added to this mix if needed.

I've never been concerned with nose pressures??

Gary

Noel Manton has springs and his son has the pushrods.