Grinding a new profile onto the stock cams?

[NismoPC]

Originally posted by G-Forces
I wouldn't put reground cams in my car if you paid me. Just my $0.02.

I agree! No regrounds for me.

I do believe Kojima mentioned regounds in his SCC topic a few months ago in the SQUISH, BOOM, BAM section. Or whatever it was called.

[Nismoboy1]

no regrinds for me neither, i'd rather use something thats tried and tested, not something that will give me an "iffy" outcome, especially since my motor has roller rockers, and i want to be able to put my car back to stock, besides JWT is the best anyways

[pche059]

Wow it was a big debate wasn't it?

ok here is the updated news from kelford Camtech

Durability wise there is little effect on the cams.The more aggressive profile will cause slightly higher loads but the grinding does not effect the hardness of the cams.The idle will be noticable lumpier but still runs ok on a std ecu. If you are doing just the cams expect 10% over what you have now.Some of the gains in the NZ model are in the computer so if you do the computer at the same time you can expect bigger gains. With the cams done the point where cylinder efficiency starts to fall appreciably quicker than rpm is rising(horse power falls quickly) can be expected to move up 1000 rpm. Sorry we do not have any dyno graphs for this engine. Most SR20DEs have a skid type rocker with hydraulicly adjusted lash.Earlier GTiRs had this and then went to a roller type rocker with hydraulic adjustment,but some later ones seem to have roller with mechanical adjustment.What other models had I couldn't say.We use roller type in the Team Kiwi cars but I wouldn't say the roller is necessarilly better than the skid type in road application.We have profiles to suit any of these systems.

Moppie yea I am from Auckland
Wassup?

[P10DET]

Originally posted by Moppie
Once you start flaming people any arguments you may try and make suddenly fall apart very quickly.

Hmmm. Let's get down to cases, shall we?

You took a pretty good poke at me. Don't bitch if I poke back harder. For now I'll let the facts speak for themselves and I'll comment later.

Originally posted by Moppie
Iv used Reground cams in both my own road car (it was a Triumph) and a Race car. I also know plenty of people who have used them in thier own road cars, and in other race cars.

So, you use them and you know plenty of people who use them? Does that tell us anything? Not really. Besides, a lot of people do things that don't make much sense.

Originally posted by Moppie
Shimming up a cam is no big deal, if your unable to fit the right sized shims, that isnt a problem with the cam, but your mechanical skills.
I think you fail to realise whats involved with grinding a freash billit or regrinding an old cam.

You think wrong. But, I also think I know why. I'll get to that in a minute.

Originally posted by Moppie
The same basic process is used for both. The cam lobes are ground to a desired profile. It makes no differnce to the grinding machine if the cam is a new a billit or an old one. Just as long as its the same basic shape.

You know, I don't give a rat about the grinding machine. I care about the valvetrain. The profile of the cam here isn't what's in question. It's the base circle and the effect on the valvetrain.

Originally posted by Moppie
As for reducing the base circle, well you can take two cams from two different engines and swap them over, and theres a high chance you will have to change the shims. Measure the base circle on a reground cam, and then on one thats done very high milage, you will probobly find the differnce is not much, certainly not enough to as you claim stress the drive train!

Not true, at least not with the vavletrain configuration of the SR20 engine. The SR20 engine neither acts directly upon the valves, nor does it act upon a pushrod. It acts upon a rocker suspended between the valves and a hydraulic lash adjuster. Altering the base circle throws the geometry of the valvetrain off. The SR20 engine specifically has a rather sensitive vavletrain. It's pretty unforgiving as anyone who has ever overrevved has experienced. With the altered geometry, the lash adjusters have a harder time.

Originally posted by Moppie
Only a VERY mild cam change would not require altering the stock cam timing to get the most out of them, and it would be a grind so mild it would be a waste of money getting it. (unless economy was your goal).
Altering the lift and duration of a cam profile also requires you to alter the cam timing if you want to get the most from it, any engine tunner can tell you this. Its one of those things that affects all engines, regardless of age, displacement, or company of manufactor

Well you are completely full of "it". You just don't know what you are talking about and it's funny because the answer is so simple.

JWT tests their cams extensively. Most companies would probably just put the roller cams JWT has prototyped on the market as is. But, testing yields improvements. JWT grinds their cams to work best straight up. When testing of their C series cams revealed that they needed some timing adjustment to produce the best results, they altered production to incorporate this timing adjustment into their production cams. That's not hard to do.

Mike Kojima has extensively tested the JWT S3 cams on the dyno using adjustable cam gears. This testing showed the S3 cams to work best straight up.

Now, with a turbo, you may find some adjusting will give improved results. But NA, they run best straight up.

So, your across the board response is just simply not true. Well designed and tested cams do not require cam gears.

Originally posted by Moppie
As for the only 10% gain.
Unless the head porting and intake and exhaust system on the SR20 is extremly poor then 10kw is not much, and I belive Nissan does make some well designed heads. Also as Primera T4 pointed out, this is an achievable gain just using some bolt on parts from another model. If Im going to buy new cams, I want a worth while power increase, and im sure most people will agree.

Well, again, you are wrong. I'm not pulling this out of my ass either. I can back up what I am saying. Sport Compact Car magazine tested several sets of cams for a number of manufacturers. Only JUN did not supply test cams, even though they said they would. The JWT S4 cams produced the greatest power increase of all the cams. It's been a year or more so I don't remember the exact numbers, but I believe they made approximately 16 more peak hp. On a roughly 155 hp engine, that is just barely over 10% (the car had a header and intake which sould yeild roughly 15 hp - also known through documented dyno testing). Independent dyno testing by friends using JUN cams put the JUN cams in the same range as the JWT.

So, these are the very best cams for the SR20DE that do not require changing the valve springs. I'm not pulling any of this out of my ass. Claims of big gains may be true for some engines/cars, but not the SR20 powered cars.

Originally posted by Moppie
Primera T4 has given excellent and unfaultalbe adivce, I was not disagreeing with any of it, just backing most of it up, as the word of two people who do seem to know what thier talking about carrys a lot more weight than the word of one.
While the word of one person who can't even spell Honda and has to resort to insults because he lacks reasoning to back up his false statements carrys very little weight.

Uh huh. Ok. Let's see who is talking out their ass here. I may have let you have it and you may not like it, and it may not fly in the face of what you think you know, but that doesn't mean I'm wrong. I can back up everything I said. OK, I take one piece of that back. I cannot provide hard data on the effect of the altered base circle. But, I can quote an automotive engineer who has worked in developement for two different OEMs, is a consultant and R&D engineer in the aftermarket performance industry, and used to build race engines for Toyota's GTP race cars. If you think you know more than him, well, I think that speaks for itself.

As for spelling Honduh, oh I can spell it just fine. I prefer my spelling. I've owned two and doubt I'll ever own another. They are good cars, no question. I won't argue that point with you. They are not for me.

As for the insults, don't forget you accused me of talking crap. Hmmm. As I said, I can back up my statements, so I think you'll lose the lack of reasoning issue - not that this is a contest. But if you choose to make it so, you'll lose. As for false statements, you haven't a prayer. I can back them up.

Originally posted by Moppie
And just because I own a Honda dosnt mean I hate or don't know anything about Nissans, my Fisrt car was a Nissan, and im curently building a hybrid kit car that uses some Nissan parts.

Hey, I never said you did.

Look, you accused me of talking crap. Well, I just overwhelmed you. I can provide hard data to back up my statements, except the base circle issue and as I said, I can quote someone with more knowledge that you and me combined times two as evidence.

Maybe I made this personal, but I don't believe I did so anymore than you. I don't know Honduhs that well (despite owning two), but then I don't go on a Honduh board telling people with a good deal of Honuh experience that they don't know shit.

I have built an approximately 200 bhp normally aspirated SR20DE (not as easy as you probably think). I have installed an SR20DET into my P10 with modifications to make it spool faster and make more power with no downside (except cost possibly). I will, however, be the first to admit to being a turbo monkey. I know a bit about them, but I'm no guru. I also know that most supposed turbo gurus don't know that much either. That's not my opinion, but the opinion of the previously mentioned engineer who is personally responsible for nearly all of the high hp turbo SR20s in the US. His results are completely duplicateable by anyone, even 3,000 miles away (as has been done). It is also the opinion of a Garrett Turbochargers engineer. I have faith in them. In addition, I race an SR20 powered car in SCCA club racing. So, I'm not without experience with this engine.

To a certain extent, I don't care what you say or what anyone buys. But, people spend hard earned money on stuff based upon what they are told. So, towards that end I will dispute things said in error. And don't confuse opinion with fact.

Now, as to why I think you believe as you do about reground cams.....

Does your Triumph use pushrods? Regrinds on a pushrod engine will not alter valvetrain geometry. You just adjust the valve lash, effectively making the pushrod longer. No big deal. Hell, even an OHC engine with cams acting directly on the valves will not alter the geometry. There are cetainly fewer issues with regrinds on these engines. But, on the SR20, and similarly configured engines, there are issues. If my original statement only applies to the SR20 family of engines, all I can say is this is an SR20 forum and I was talking about an SR20 engine.

[Nismoboy1]

someone just got told...does this moppie dude know who he's talking to!!! i suggest he picks up a Sport Compact Car Mag. and read george's article lol :sun:

[P10DET]

Originally posted by Nismoboy1
someone just got told...does this moppie dude know who he's talking to!!! i suggest he picks up a Sport Compact Car Mag. and read george's article lol :sun:

Hehe. Thanks John, but I'm really just one of the guys.

[Moppie]

Originally posted by P10DET


Hehe. Thanks John, but I'm really just one of the guys.

One of the guys with a bad attitude, when it comes to holding a debate.
Iv only ever looked at one copy of SCC, its rather hard to find down here, and when you do find it its also rather expensive. And just becuase you right an article for a magazine dosnt make you an engine Guru!

What you say about the effects of changing the base circle does make sense. However you would have to look at how much the base circle is changed before it becomes a problem. Remember that a cam suffers wear over time, and the base circle will change as the engine ages, so Nissan must build allowance's into the valve train for this.
If your regrind of the cam takes you well below the tolerances allowed for normal wear then you could have a problem, but this is only likly to occur on a very aggresive profile, something that only nets a 10% gain is likly to be quite mild.
Unless the SR20 head suffers from extremly poor flow characteristics, in which case some head porting would also be a good idea.

Please also note the Reply that pche059 got back from Kelford, they have been manufactoring cams for a lot of different motors for a long time, and by the sound of it designed the cams for the Team Kiwi Primera, which is possibly one of the fasted 2.0L touring cars currently in New Zealand. If you want to go off what the experts say, then they are certainly experts in he field.
(and if you hadn't noticed its possible for experts to disagree.)

[Moppie]

pche059

Yes im auckland based. (well close enough )

I recomend you ring Leading Edge Cylinder Heads in East Tamiki, and have a chat to Dwight. 274 6114. He may just pass you onto someone else, or he may say he can to X and you will get Y gains, or if you want A gains then he can B. But Im pretty sure he will suggest some porting to go with a custom cam grind.

If you only want to drop in some cams, then as well as Kelford you can also check out,
CSL (cam shaft services) in Palmy North, 06 356 3700
They have a similar reputation to Kelford, and I think have been around almost as long.

[P10DET]

Originally posted by Moppie
One of the guys with a bad attitude, when it comes to holding a debate.

If you look back, you will see that you pulled the attitude first. I didn't give you an attitude until you gave me one.

I'm more than happy to extend an olive branch here, but not if you cannot admit at least that.

Originally posted by Moppie
Iv only ever looked at one copy of SCC, its rather hard to find down here, and when you do find it its also rather expensive. And just becuase you right an article for a magazine dosnt make you an engine Guru!

OK, first of all, I never said anything about that. Someone else did, so please don't make out like I said or believe that.

On the other hand, I'll wager a pint of your favorite that I have more experience with the SR20 engine that anyone here. I also have access to rather significant SR20 resources. I'm not trying to brag or cop an attitude with you. I'm not trying to be a self-proclaimed guru. It's just the facts and I am here to share as much information as I can with people.

All of the things I have said on this subjects are facts that I can provide hard data on. I have clarified that the base circle issue is not backed up by hard data I have, but the information from an engineer with better credentials than any of us and I'm certain even the shop you are talking about. Again, I'm not trying to be a jerk about this, but like I said, this guy built Toyota's racing engines for their IMSA GTP program.

So again, please rest assured I'm not proclaiming myself to be the God of all things SR20 or anything for that matter. I can be as full of shit as anyone else and am all too often. But I have my ducks in a row on this one.

Originally posted by Moppie
What you say about the effects of changing the base circle does make sense.

Thank you. I think we can find some common ground here.

Originally posted by Moppie
However you would have to look at how much the base circle is changed before it becomes a problem. Remember that a cam suffers wear over time, and the base circle will change as the engine ages, so Nissan must build allowance's into the valve train for this.

True. But I think (only an opinion here) that any regrind that does not significantly change the base circle will not be able to produce any power worth talking about - at least not on an SR20. I admit I don't have the facts on this on particular point, but I can inquire about it.

Originally posted by Moppie
If your regrind of the cam takes you well below the tolerances allowed for normal wear then you could have a problem, but this is only likly to occur on a very aggresive profile, something that only nets a 10% gain is likly to be quite mild.

OK, I have to set this straight again. The best cams available for the SR20 that do not require valve spring changes only make 10%. That is the very best (except I don't know anything about Piper cams). This includes Tomei, Toda, JWT, JUN, and a few others.

I think your assumptions about gains is off. Again, I am working from independent dyno testing that was done using procedures to ensure repeatability.

Originally posted by Moppie
Unless the SR20 head suffers from extremly poor flow characteristics, in which case some head porting would also be a good idea.

Porting will help, but please don't make the assumption that only making 10% gains will the best cams is because the ports suck. It's more that the SR20 leaves a lot less to be gained than many engines. Don't forget that this engine was designed specifically homolugation for racing.

Originally posted by Moppie
Please also note the Reply that pche059 got back from Kelford, they have been manufactoring cams for a lot of different motors for a long time, and by the sound of it designed the cams for the Team Kiwi Primera, which is possibly one of the fasted 2.0L touring cars currently in New Zealand. If you want to go off what the experts say, then they are certainly experts in he field.

OK

Originally posted by Moppie
(and if you hadn't noticed its possible for experts to disagree.)

Yep. Happens all the time.

So, as far as all that goes, please remember that you accused me of talking crap. Well, that's not the case and as I said, I can support everything I said. So please remember, that while I may have an attitude about this, I wasn't the first to bring an attitude to the table. You might want to cut me a break here. Don't poke me in the eye and say I have a bad attitude when I get pissed.

Publishing an article doesn't mean anything in this argument and I never said it did. My knowledge didn't change one bit by publishing the article. There are certainly folks out there with more knowledge than me, certainly including the SR20 engine.

[pche059]

Hm.....
i feel bad now...sounded like i started world war 3....
just take it easy guys....

I think I am gonna wait till JWT brings out the roller rocker type cams too....
the car is still pretty new.... don't wanna do anything that could have a chance fxxxing up the engine...

well...i can always do the header first...
hope that gain is enough for me to sit back for a while and wait till the new cams come out

[P10DET]

Originally posted by pche059
Hm.....
i feel bad now...sounded like i started world war 3....

Nah.

Originally posted by pche059
well...i can always do the header first...
hope that gain is enough for me to sit back for a while and wait till the new cams come out

A HS header is the bang for the buck performance leader.

[Moppie]

Yeah P10DET im sorry, I did accuse you of talking crap to begin with.
I just have a problem with people who come along and offer little tangable proof for what is nothing more that thier own opions.
And my reading of your post gave me that opion.

I admitt I Dont know much about the SR20 engine, But I still feel that only a 10% gain from any cam is not very much. This would mean the SR20 head was already operating at its maximum flow levels from the factory, (which must be very poor) or the valve gear is on the extremly weak side. In which case BAD on Nissan, and from my experiance that sounds rather out of the ordinary for a Nissan engine, who have a repuation for building VERY strong engines. But theres an exception to every rule, and I will take your word for it.


You dont need to grind significant amounts of a base circle if your increaseing the lift. And since the cam operates through a rocker, this amplifies the amount of movment from the cam lobe, so you only need to remove a VERY small amount of material from the base circle to get a noticable raise in lift. I would have thought the amount of material removed on a mild street cam would be within the limits of Nissans design.
Did the expert you talked to about this mention actual examples and talk form experiance with mild street regrinds in an SR20? or was it only a theory, or experiance with wild race regrinds? (which would require much more material removed from the base circle, and cause problems.)

Kelford is a well known company, and does test all thier products.
Im sure thier not going to sell a product that will cause Valve train faliure, we have some very good Consumer protection laws here in NZ, and Manufactors have to take note of them, or it can get very expensive for them.


pche059, No WW III, I'll leave that up to Mr Bush, its just a very lively debate.
I suggest you copy what P10DET said about the base cicrle and send it to Kelford and see what they say. If they say they've taken this into account, or that no its wrong here why, then go get the cams and enjoy the hp boost. You have the consumers institute to back you up in the unlikly event you have problems.
But if they try and brush it off, or make up some PR crap excuses then dont get the cams. Find some billits and a profile you like and get it ground.

[P10DET]

Originally posted by Moppie
Yeah P10DET im sorry, I did accuse you of talking crap to begin with.
I just have a problem with people who come along and offer little tangable proof for what is nothing more that thier own opions.

In that we see eye to eye and I applaud you! There are a lot of people around who have nothing more to offer than an opinion based upon something they heard 3rd hand or worse.

Originally posted by Moppie
You dont need to grind significant amounts of a base circle if your increaseing the lift. And since the cam operates through a rocker, this amplifies the amount of movment from the cam lobe

Hmmm. Tomorrow I will pull out the specs from the FSM. That will be interesting. I'm about to go to bed now.

Originally posted by Moppie
Did the expert you talked to about this mention actual examples and talk form experiance with mild street regrinds in an SR20? or was it only a theory, or experiance with wild race regrinds? (which would require much more material removed from the base circle, and cause problems.)

I don't know the full spectrum of his experience with regrinds, but I know he was involved with dyno tests of reground "street" cams that really sucked, despite huge hp promises. I'll try to find his message about this tomorrow as well.

[Moppie]

Peace it is then.
What name to you apear under in SCC? Ill go find one tomorrow after my exam and have read of your articles.

[P10DET]

Originally posted by Moppie
Peace it is then.

I'll drink to that.

Originally posted by Moppie
What name to you apear under in SCC? Ill go find one tomorrow after my exam and have read of your articles.

George Roffe

I've only had my first article published. In fact, I just got my copy of the magazine yesterday, so you won't find it on the news stand yet. It's in the December issue and is a tech article detailing how to swap a Bluebird SSS SR20DET into a P10 G20 (Primera). I've also got a few cool sidebars on some go-fast stuff for my DET.