Top end sugestion, valve springs and rpms

[peterock]

curious what is going to be said here. It was suggested to me that the valve springs are way too stiff and the rpms should be lowered to around 10500-10800. This would increase reliability and also improve performance and longevity of the cams.

just stirring the pot

[wanablaze]

In all honesty, I think a beehive design may be better than a dual spring setup.

[cannondale27]

Bunk ever see the pressures that dragsters and even just plain V8 streetcars run at?Double and even triple what we have.If a cam is made properly and valves dont float it shouldnt wear with 3 times the spring pressures we have.

[wistech]

QUOTE (peterock @ Apr 23 2007, 12:56 PM) <{POST_SNAPBACK}>

curious what is going to be said here. It was suggested to me that the valve springs are way too stiff and the rpms should be lowered to around 10500-10800. This would increase reliability and also improve performance and longevity of the cams.

just stirring the pot

Can you explain how lowering the rev limit and using weak springs will improve performance?

[peterock]

QUOTE (wistech @ Apr 23 2007, 09:20 PM) <{POST_SNAPBACK}>

Can you explain how lowering the rev limit and using weak springs will improve performance?

I actually can't. Kind of why I posted it. I know it goes against certain ideas, but I would think Dan Crower knows what he is talking about. Just part of some of the ideas he was throwing at me last week on the phone.


I guess maybe we need to look at too much isn't always a good thing? Obviously it takes more pressure for the cam to push the valve open which could relate to a loss in power. It is possible that some areas are "overbuilt" causing a loss in power. (Just generalizing here). Just sharing an idea that was thrown out there.

As far as the rev limiter reduction, that would be to help prevent any valve floating and added wear caused by higher rpms. End result.........longer lasting motor?

[cannondale27]

I agree lower rev limit will usually make a longer lasting motor and lower spring tensions makes HP but if your valves float you need more tension or lighter valves.He probably is freaking over our cam profile.It is pretty radical.My previous statement was in regard to cam wear.Not power.

[peterock]

With the cam wear, I believe part of his reasoning is that due to the amount of force being exerted due to the valve springs is adding to the cam wear. Which does make sense, but we do have to find that line where there is still enough spring pressure to prevent valve float.

Might not be the route for everyone depending on their application and definitely hasn't been proven yet. However, for the average trail rider it may be worth looking into?

Also,

billet cams can be made. he hasn't given me a price yet or a definite he will make them as they aren't the simplest design to make and has to decide how much trouble he wants to invest first.

[peterock]

Looks like I may be getting a set of reworked stock cams in about a week. They are looking into rewelding some worn cams to see if they want to make that an option as well.

1.Plan is going to be to put in new undercut stock cams with reduced rpms and softer valve springs with stock piston, no porting/polishing. compare that to my stock dyno numbers.

2. Same set-up as above but with higher compression piston. probably about 4-6 weeks out.

3. Here is the mind blower for some of you. Porting may not be done, he may go the oposite way. Looking at the end of the year before we are that far though probably. I do have two heads to send back and forth for him to continue to mess with though so it may happen quicker.

[timbomoose]

"Looks like I may be getting a set of reworked stock cams in about a week. They are looking into rewelding some worn cams to see if they want to make that an option as well."

Make sure to get the cams heatreated afterwards.Wistech has a place that can have them hardened and coated that has been proven to work.Plain hardwelded cams have proven to not hold up.Even for a few hrs.Different places have tryed with same results.

"1.Plan is going to be to put in new undercut stock cams with reduced rpms and softer valve springs with stock piston, no porting/polishing. compare that to my stock dyno numbers"

Undercutted cams will give a higher lift which can give more power. Stock heads on a flowbench have shown a loss of flow with high lift.I believe it was the intake.Ported heads showed gains with higher lift.Stock motors due fall off before the rev limiter and there is no power gain by reving as high as they do and lower rev limiter will increase entire engine life.No other stock quad has a 11500 rev limiter.Higher compression will give more power but more strain on the entire motor.Cam design is a big thing to get the most out of your motor with high compression.

"Porting may not be done, he may go the oposite way"
Not sure what you mean if you take away or add material its still porting.

Good luck with your project. Hopefully some more power and reliability will be found. Just posted this info to help out with stuff that has already been tryed and tested to save some of the R&D time and money for you.The big thing is not to run hardwelded cams unless gone through the treatment. Has worked on hardwelded cams. Contact Wistech for more info. on the process. Good luck and keep us posted on your progress.

[peterock]

Thanks for the info Timbo. You caught what I was trying to imply with the porting, most people hear porting and they automatically think bigger.

Hoping when I drop the cams in, we see a nice midrange increase.

I may have to get my hands on a 2nd motor so I can keep my race motor in one piece for the season since it has started.

QUOTE

"INNOVATE! DON'T IMITATE!" "Improve AND PROVE!"

Your quote is exactly what I'm trying to accomplish. Not trying to step on toes or throw anyone's hard work out the door so I hope no one takes it that way. And no one's past work is being ignored, just have a fresh mind looking at the puzzle.