To those who ask me to do a search... I DID!

My questions are geared towards running "mild" cams on a 1998 TypeR. Currently I am considering the SPOON or TODA-A spec cams.

It has been widely accepted that these two cams can run with the stock valve train up to 9000RPM without any problems. However I do have some questions and comments regarding both the intake and exhaust valve springs.

Now since I own a 1998 R with softer intake valve springs I think it might be wise to swap out my intake springs for the newer stiffer ones. This might not be necessary but I'll be buying a little insurance. As the lift on the new cams is pretty much un-changed from stock this line of thinking makes me feel quite comfortable.

With respect to the exhaust springs I am a little more concerned. In a recent thread someone made a comment that they had experienced "flat-spotting" of the exhaust cam when running with the stock springs. Now this might be an isolated occurrence because I have never heard of this happening previously. What are everyone’s thoughts on this? Should I be concerned?

If there is indeed a problem with the exhaust cam springs then what can be done?

One thought that I had was that perhaps the old intake springs could be used on the exhaust. Does anyone have any insight into this? Out of interest, looking at the similarity in specs between the stock intake and Spoon exhaust cam one might speculate that the same springs could be used IF the valves were the same weight.

Does anyone have any information regarding the differences between the intake and exhaust valve springs?

Any help with the above would be greatly appreciated!

Thanks,

 

If the stock springs limit the stock redline to 8700, how can they be good to 9000 with aftermarket cams?

 

Who says that the stock springs limit the stock redline? There are many factors that the manufacture considers when they set the redline. Perhaps the increased wear assoiciated with increased engine speed was something they did not want to incounter. The shortened lifespan would result in more warrentee claims.

There is plenty of evendence to support the fact that the stock springs can spin the stock cams to 9100RPM safely!

Regards,

 

Well better be safe than sorry, go with a complete stiffer set of valve springs. I have type-r cams and I use Toda valve springs. Funny that you should mention about "flat-spotting" because I flat spotted my exhaust cam as well and i was using Mugen valve springs at the time, and i cracked one of the springs. My rocker arm on cyl. 2 was also damaged and needed to be replaced.

Just go with Toda or Spoon vavle springs to be safer.. but still no guarantees.

 

Are you saying that you flat spotted a stock exhaust cam with Mugen valve springs? Mugen valve springs have the same stiffness as stock springs. I can't see how you could have had problems with them.

I don't want to just throw in stiff springs for the sake of it. Too stiff and you will increase losses and premote even greater cam wear.

 

stock valve springs are good for the toda a's, they should be for the spoon's as well.

 

I would recommend ITR intake valvesprings on both intake and exhaust sides.
If you are really worried, then get portflow innner springs at the same time.

 

Sgt,

Thanks for the advice! Can you offer any explenation as to why that would work? Obviously that is something I was considering doing but I want to make an educated decision before I try it.

Would be great to know (but I can't seem to find it) is the weights of the intake/exhaust valves. As well, what are the relative stiffnesses of the stock intake/exhaust valve springs.

I'm not so much worried as I simply want to insure that the valve train has the same rugedness as the stock system.

Thanks,

 

stock springs are some what decent...

look at the chart... http://www.importreview.com/reviews/valvesprings.html

The higher you rev, the more stiff you want to be. The Portflow spring kit has a max without float of around 9600-9700.

I believe this spring kit to be the best on the market for the price. If you want to rev past 10,000 RPM, you will have to go to the Ferrea Kit, that is around $800. that will do 11k RPM.

back to the topic...if you just change the inner, you will be able to accept those Toda A's and rev to 9500, if your block was built to do so. I would say the limitations of the stock ITR spring is under 9k. Probably like 8700-8900 with a mild cam.

Hope I helped.

Jeff

 

Jeff,

I will be running with the stock bottom end for the time being. I don't plan on bringing the rev limit past 9000RPM and might keep it a couple hundred below that for comfort.

I was hoping to stick with the stock valve train and upgrade my softer 98 intake valve springs with 00/01/JDM ones. I can do that fairly cheaply. Now I understand that the exhaust springs might be the weak link based simply on the lift of the new cam, not the speed.

Do you have any data on the stock exhaust spring? Have you ever run the stock intake springs on the exhaust?

Much thanks!

 

What spring retainers are you using?
When I was puting the motor together, I decided to replace the stock retainers for skunk2 titanium retainers. I have 00 springs and cams, and I have revved the engine to 9500 RPM a number of times with no damage.

 

Are itr valve springs safe to use with Jun 2's?

 

yes

 

Yup, flat-spotted my stock exhaust ITR cam, while i had the Mugen valve springs on, I also cracked one of my Mugen Valve springs as well. I was just driving normal one day when the valve spring went bust on me.

 

If you are going to waste your money on another set of stock springs, just
spend the money on 8 intake outer springs and a set of portflow inner springs.
Stock exhaust spring is the same as the stock gsr intake springs.
Stock intake springs work great on the exhaust side with mild cams.

 

Stock bottom end is fine to 9500 I think.. but there is no sense in running it this high.. even with a *mild* cam. Even with Jun3 or Toda B... you're probably gonna shift below 9500.
I think in general, people have had a large misconception of building a "block" to withstand revs. Granted, the GSR/ITR block has the cooling jets and bearing girdle.. this is good for continuous high rpm usage.. but if you want my opinion, I have no problem revving a LS or CRV motor to 9000 or so all day long.
I'd be a little more cautious on a block which was built on the "loose" side of clearances, because I think you'd be more prone to spin a rod bearing with that setup over 9k repeatedly.. but ****... factory bottom end? Rev it to your heart's desire. Honda builds those ******* so tight 90% of the time, it don't matter. They want it to last. That's why it's built like that.

Yes, this is true. I have taken my stock springs to over 9000rpm on a few occasions.. no problems. Most cams stop making power at 8500 though.. even less most of the time.

Hope I helped.

Jeff

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