HKS or WEB cams?

[Johnny Bravo]

Originally posted by dyezak


Bah, it's nothing crazy or fancy...just a grouping of parts that are proven to work well together. There are some guys around our area that have some CRAZY setups, Russ Cox, Brad Brooks to name a few. Both are on the verge of 9's. 75/80 (barf)...that is the worst track I have ever been to and will never run my car there...EVER. Mason Dixon is OK and so is MIR. There are no great tracks around here, although I'm going to check out Atco in May to see how that one is.

! I totally agree about 75/80...the box is a total shithole. No matter what I did I couldn't break into the 13's even with my FD. NO traction whatsoever! Do any of you guys ever hang out at the Holiday Theaters on 40 behind the Holiday Inn? I used to go there all the time & hang out with the car crowd there then sometimes go down to Lilly Ponds. Never any real fast DSM's there usually...a couple of MKIV Supras & whatnot though.

 

[dyezak]

Originally posted by Johnny Bravo



! I totally agree about 75/80...the box is a total shithole. No matter what I did I couldn't break into the 13's even with my FD. NO traction whatsoever! Do any of you guys ever hang out at the Holiday Theaters on 40 behind the Holiday Inn? I used to go there all the time & hang out with the car crowd there then sometimes go down to Lilly Ponds. Never any real fast DSM's there usually...a couple of MKIV Supras & whatnot though.

Every once in a while I'll do the Theater/Lilly Pond thing. But it's so far to go to se the same cars run. I never took my car there, heck I rarely take my car to the street races. Texas tags, LOUD exhaust, 3 a-piller guages an AVCR an AFC and a pocketlogger on the dash and flames out the exhaust make it a sure fire cop magnet. I only take my car out when I KNOW there'll be a $$ race for me. Otherwise I drive out to 40 and meet up with some friends and ride with them. Plus now that I have a built bottom end there will be even less of me at street races in *my* car. I have a couple of fast wrench turners (friends cars I built) that I ride in. Ever sceen that "Raceredi" commercial on MTV? I built that GSR that was in it (turbo 325hp B18 GSR...ran 12s). Now we got 2 other cool projects to ride in...an 89 240SX with a SR20DET and an S15 front end, and a 96 Civic EX with a JDM B18C5 (about to be turbo'd). Both of those cars have a low street profile and stock bottom ends so we can cruise those. I might pick up a new project for this summer (for when mine is finished)...a 1976 Datsun 240Z to put a SR20DET 6sp in and a widebody kit on it. I still haven't decided on that one.

 

[pneumo]

Wow! I just read all of page 3 in this thread and got absolutely NO info on cams. Way to keep a dead thread going, guys.

 

[TheHater]

Fuuuk the web cams in any grind. There street grind is OK, there race grind is WAY to big for 2L. You really need cam gears to get them running properly.

T28, Bigt28, Big or small 16g,18g,L1r:
get the 264/264 combo. This will make a wicked fast spool w/tons of midrange. Local guy had sm16g and 264's, and it just nasty quick. Also seen a dyno of another sm16 w/264's laying down 350hp/350tq. No web grind can do that!

20g,green,l2r or t3t4 equiv:
264*272, you can go w/272's. Just depends on other mods and what you want, plus the ability to raise the limiter past 7500. Plus fwd or awd can play a role in the decision.

Fp red, l3r, fp 30 or any big t3/t4 combos:
272/272 only. Look what the big dogs are running, Ok?
Though to get the most out of these cams I'd expect a Sheetmetal intake, ported head if its a 2g, 1g could get away w/o it and a motor capable of running to the 8500 range.

The crowers are a direct copy of the HKS's and still dont compare when it comes to quality or performance.

People dont seem to understand that this isnt a catback, just because one cheaper doesnt mean it'll give the same performance. This in an internal engine part, $100 bucks more for the BEST cam on the market bar non that is run the the fastest dsm's in the world.

And Nawzzlaser, sometimes you really need to get a life and quit writing novels on things that someone told you about sometime.

 

[NosLaser]

...And Nawzzlaser, sometimes you really need to get a life and quit writing novels on things that someone told you about sometime....

Blow me pantywaste. Just because your feeble mind doesn't understand what's being said doesn't mean you have to open your c*ck holster.

That being said, I'm going to go out on a limb here for the benefit of the people that are actually LEARNING in this thread, and not you useless f*ckholes on here to do nothing other than piss like little b*tches. And if you have a personal problem with me, bring it the f*ck to ME!!! Don't wave your little wee-wee on an internet forum and waste everyone else's time, and clutter the place up with your little internet toughguy p*ssy ass bullshit.

When it comes to cams, everyone needs to understand something. On a turbocharged car, you are making power with the TURBO. The cams can be used to make changes in the powerband, and where it occurs, but bottom line, people didn't get into the 11's, 10's, 9', 8's etc. in a 4 cylinder by swapping out different cam combos. They did it with tuning, and larger turbos. Period. Argue with that statement and you are just being an assclown. I hear everyone bantering about degree'ing the camshafts, and how the HKS cams are ground true, etc. That's great! If you want to install the cams straight up and leave them there, then sure, the HKS cams may or may not offer better performance than the Webs. But what are you doing with adjustable cam gears? You will be changing all of that during the tuning process. Like I had mentioned before, it's a black science. For example; if I were to tune a car that I didn't build, it would be nice to have gotten to measure the piston dish, the deck height, the gasket thickness, how much the head was milled, etc. so I know what compression rato I'm dealing with. But you know what? When I start tuning the car, I'll focking figure it out! It would have been nice to know beforehand, but it's one of those things I can get around not knowing. Same thing with cams. If you want to install them straight up with a degree wheel, etc. then cool, it gives you a nice starting/reference point. But when I start to tune the car, I'll feel when it comes into power, and I'll pay attention to the powerband, and I'll be able to figure out where I want the cams to be via adjusting the cam gears. Maybe the HKS's are ground a bit more true than the Webs. OKAY. I'll likely be changing their characteristics anyway, so what would it matter? It's not something I can explain on an internet forum, but it's something I will prove via dyno sheets and timeslips with my current project car. I don't have the slips and dyno sheets online of my Laser's performance, but plenty of eyewitnesses (including where I dyno'ed the car at Wrighttouch) can attest. I think I've already proved my ability to tune a car. But, this time I will make sure I shove timeslips and dyno sheets down your throats to prove I'm not on here 'rambling.'

This is the big problem with the internet. You all read something, and you bicker and argue over the littlest minute details that if you really HAD A CLUE you would understand that they really don't make or break anything. I will make power with whichever cam I install. Period. The Webs are much more affordable, I've had good luck with them, so I will continue to use them. I remember talking to Sean and Terry Glazer a couple years back. They used to run the Web cams and then they switched to the HKS's. In conversation, we brought up power differences between the two, etc. His answer to me was "you know what? Last year Web was paying for our cams, so we used them. And this year, HKS is paying for our cams, so we're using them. Did we make any more or less power with either? Nope. But it's nice to get them for free."

Bash me on the internet all you want; some people will listen to me and go faster (and it seems that at least some people listen because if they didn't, I wouldn't have that title in my sig) so hey, that's cool. You all can jump on your little anti-NosLaser campaign all you want. I'll prove it with my car. Again. Just keep your little circle jerk over on NABR or your AOL chat room or wherever you do it, and don't bring that bullshit over here to detract from those who actually want to LEARN about cars and not sit here and b*tch for hours on end about little details that don't matter anyway, but are just so popular to b*tch about on the focking internet.

Regards,

 

[jayntguru]

Noslaser, where's your timeslip? I can't find your name on dsmtimes.org anywhere. You must be near the top with your mad tuning skillz.

 

[NosLaser]

Jay,

My old timeslip was on the dsmtimes page but it got updated, and I never re-sent it in. It's old news anyway..that car hasn't been around in almost 3 years. The Talon will have full documentation, just for you pal.

And TheHater,

I need to get a life? I'm not the one posting on the damn internet at 3 am (12 am for you) on a Friday night.

Regards,

 

[DSSA]

Aslan,

I'm not quite sure where you're getting your attitude from.

From day 1, you've been a big-mouth. You spew more "psuedo-tech" babble than anyone else I've seen on here...which is saying a lot.


Posted by NosLaser:

Just because your feeble mind doesn't understand what's being said doesn't mean you have to open your c*ck holster.

That's funny that you say that as your intial "novel-post" on here leads someone (who knows what they're talking about) to believe that *you* are the one who doesn't know what you're talking about. You spew general tech stuff out like it's (in your words) "Black Magic" (I especially liked how you make anti-lag setups look like they're something new and innovative). And I liked the description of how a diesel operates-- too bad you either have problems expressing things or need to read up on that as well.

Posted by NosLaser:

When it comes to cams, everyone needs to understand something. On a turbocharged car, you are making power with the TURBO. The cams can be used to make changes in the powerband, and where it occurs, but bottom line, people didn't get into the 11's, 10's, 9', 8's etc. in a 4 cylinder by swapping out different cam combos. They did it with tuning, and larger turbos. Period.

Good god, this is what I'm talking about in a nutshell. Statements like this make me fear for the people on here that actually listen to you. I could write a 3-page summary of how either misleading or out-right wrong aspects of this statement are. Perhaps you need to go back to the beginning of the learning cycle and remember that an engine is (in its most basic form) simply a pump. In turn, these cams are the controlling factor for how long the valves on said pump are opened, and to what extent. But no, cams do nothing for power.

Posted By NosLaser:

But, this time I will make sure I shove timeslips and dyno sheets down your throats to prove I'm not on here 'rambling.'

This sounds like the same "run-at-the-mouth" Aslan I'm used to. Seems to remind me of all the smack-talk a while back about how you were going to run Jesus and make his car look bad. Well, Jesus since then has ran 9s the 1st trip out to the track with his car. You on the other hand haven't proven jack in the 2 years since then.

Posted By NosLaser:

Bash me on the internet all you want; some people will listen to me and go faster (and it seems that at least some people listen because if they didn't, I wouldn't have that title in my sig) so hey, that's cool. You all can jump on your little anti-NosLaser campaign all you want. I'll prove it with my car. Again.

1) That little "title in your sig". This makes me laugh.
A) Quite a few people on this site are new to the scene.
B) I could probably name 10 people on this site that would run circles around you in knowlege. One of them being a certain guy you like to run your mouth about. If you and Mr. Evans ever sat down and spoke tech, I *guarantee* you that he'd lose you in the 1st 5 minutes. Then again, I'm sure you'll argue this fact. Just note that Shepherd has admitted that Scoot can lose him as well. But you probably know more than Shep...

2) What *have* you proven with your car? All I've ever heard about is you running a large shot through an otherwise almost-stock motor and claiming to have raced "Guy X's $150,000K Viper/Corvette/Ferrari" that we're supposed to take your word on.

End point: Either get off your high-horse, or actually *DO* something that proves your tuning ability you claim to have. Some people may buy the claims with nothing to back it up. But after spending so long hearing about it, with nothing to back it up with, a lot of us don't.

"The proof is in the pudding"...words to live by in this case.

 

[NosLaser]

...That's funny that you say that as your intial "novel-post" on here leads someone (who knows what they're talking about) to believe that *you* are the one who doesn't know what you're talking about. You spew general tech stuff out like it's (in your words) "Black Magic" (I especially liked how you make anti-lag setups look like they're something new and innovative). And I liked the description of how a diesel operates-- too bad you either have problems expressing things or need to read up on that as well....

Where in any of my posts did I say this is new and innovative? There are things that have been around for quite some time, but so few people understand them which is why people go so slow with so much money spent. Maybe you self proclaimed Gods already know about it, but most people don't. So why don't YOU get off your high horse and let other people learn instead of coming on here telling me how 'basic' my info is. I know it..you know it...when you read a book, do you call the author and complain to him about how he wastes the first 3 chapters explaining stuff before delving into more tech? Let's call a spade a spade. You are here to be an ass to me, as are your little tool friends, and for NO OTHER reason. I've helped MANY people on this board, and on others (do I REALLY need to spend the several hours it would take to quote posts after I have helped them?) and I'm here for a good reason. Explain to me right focking now WHY you are here in this thread bashing me? Have I given ANY bad or misleading info? POINT IT OUT TO ME IF I HAVE. Otherwise, you are here just to be an a*shole. The proof like you said, is in the pudding.

When I mentioned in the excerpt of how cams are a small factor, I was hoping the Godsend know-it-all's like you would have grasped the concept I was getting at. Of COURSE cams help make power. Of COURSE they are a very important part. I figured we could be safe in assuming that part as common 'BASIC' knowledge. But let me ask you a very simple question. Do you think if John Sheppard did nothing other than take the cams out of his car, and go back to stock cams and re-tuned it, do you honestly think he would fall to 11's? Even 10's? My guess is he would likely still be able to pull off 9 second passes even with the stock cams. THAT was the point of what I said. In a car that ran high 14's from the factory, that is now running mid-low 9's, how much of a factor did those vainglorious HKS cams have? Now how big of a factor do you think that huge garret turbo and nitrous setup is? Do you FINALLY understand my point yet? Go ahead and start on your 3 page summary at any time...

...This sounds like the same "run-at-the-mouth" Aslan I'm used to. Seems to remind me of all the smack-talk a while back about how you were going to run Jesus and make his car look bad. Well, Jesus since then has ran 9s the 1st trip out to the track with his car. You on the other hand haven't proven jack in the 2 years since then....

Now we are going to name-drop on old stuff huh? I AGREED to race him whenever he wanted. He refused to come down and race me. If you want to REALLY dig up old skeletons, he threatened to 'put a bullet in my head' and then cordially invited me to drive up to Orlando on a Saturday night, and he said I had to come alone, and meet him and his friends at their 'race spot' and that we would run from a dead stop, his AWD vs. my street tire'd FWD. Riiiigggghhhhttt. He would not come down here to race, and I sure as hell wasn't going to drive up there under his 'conditions' after threatening to shoot me earlier that day. Get a clue before you bring up old bullshit. And I'm sooo sorry I wasn't born into money like Jesus, and I can't afford 3 Supras and 5 DSM's and a million dollar house, etc. Want to know my excuse? It sure ain't lack of know-how. Originally I was going to build my Laser up, and had just put the rollcage in, and began provisions for the belly pan and rear diffuser (plans were to attack Bonneville) and the shop in Florida had a fire, and my car was burnt down. The insurance cut me a $1500 dollar check for a '1992 Laser' and I was left with just about nothing. Then saved up, and bought my Talon, and am currently building that up. It's money. Where is your 9 second car? I'll bet it's a money issue, and not a knowledge issue..just like me. Anywhere else you want to go with this dead issue?

As far as talking tech and and that nonsense, there is always someone better. That statement means nothing because I'm not here to say I know it all. I'm here to help people which I have. I'm here to talk about cars, which I enjoy. I'm not here to take bullshit from you and your little clique because it's completely uneccessary. Am I profiting from what I'm doing? Am I taking money or business away from ANY of you? The answer to both of those questions is no. So why, when you still haven't given me an example of what I posted that is bad information, are you and your g*y tribe so insistent on giving me a hard time? I really think it's funny that whenever an NABR guy comes on here, all of a sudden he and about 3-4 of his minions come out of the wood work and trash me for a few days, and then leave. It's the world's biggest soap opera with you guys. You haven't had a problem with anything I've said on here before (or at least you never mentioned it) but you have a WEALTH of opinion when your idol comes on here and opens his mouth. Why is that?

Regards,

 

[NosLaser]

One more thing. When I mention 'black science' I figured someone as intelligent as you would know what I am referring to. But, since you don't, I'll explain it. It's having a feel for what's going on. It's the reason why you can't help someone tune their car over the internet..you have to 'feel' what's going on for yourself. I'll use a really bad example because its something else I'm into. I'm pretty big into reptiles; large constrictors in particular, and it's also a black science there. You have to feel, and read the animal's mood because if not, you could end up in big trouble. You can't just tell someone how to handle them; you have to experience it through trial and many potential errors. That is all. I just wanted to make sure I cleared that up before you started selling 'NosLaser Black Magic Wands' on ebay.

Regards,

 

[TheHater]

Well, nawzlaser you continue to make an ass of yourself. Let us see when and where:

Posted by the "Voted DSMTuners Most Knowledgeable Member"

My guess is he would likely still be able to pull off 9 second passes even with the stock cams. THAT was the point of what I said. In a car that ran high 14's from the factory, that is now running mid-low 9's, how much of a factor did those vainglorious HKS cams have?

Are you really that stupid to say Shep could run 9's on stock cams? I hope not, but I'm sure you could run 8's . I guess nobody knows how good those stockers are because for some reason Buschurs using those shitty HKS 272's, maybe you should call him and tell him to use his stockers.

And the title "Voted DSMTuners Most Knowledgeable Member" holds about as much water as your mom saying your the most handsome young man. It means NOTHING, so get over it.

And the comment about me posting at 3am on a friday. I tore a shoulder muscle on thursday and am not going out because of it.

We all await "Voted DSMTuners Most Knowledgeable Member" novel crying how he knows all, then start cussing making internet threats...ooooh

 

[TALONTED]

Dont know about the argument above but here is my $.02 on the Cams!
I have HKS 264/264 with my big 16G. I love them. They added power I could definitly feel up top around 6-7k. Power use to DROP after 6, now it pulls! I am upgrading to a 20G fairly soon and I am keeping the 264 combo. I dont believe in the 264/272 combo. Its all hype to say you have a "race cam". Nate from DSMotorsport went 10s on his 50 trim with 264s. But whatever, web cams, as soon as I heard of so so quality, why bother? why take the risk. Just get the HKS cams, 100% quality and performance.

Tom

 

[NosLaser]

...Are you really that stupid to say Shep could run 9's on stock cams? I hope not, but I'm sure you could run 8's . I guess nobody knows how good those stockers are because for some reason Buschurs using those shitty HKS 272's, maybe you should call him and tell him to use his stockers....

Brwahaha!!! Dude, you are such a tool, but at least you are good for a laugh. I refuse to explain myself any further if you are too stupid to understand what I am saying. No d*ckbrain, I'm not saying that the stock cams are BETTER, I was making a point to say that the overall turbo sizing is a much larger factor in the power and times that he is running than the cams. And yes, I stand by my previous statement that yes, he would likely still be able to click off killer fast times even with stock cams. Would he lose power? Of course, toolshed! But would he go from 9's to 13's? I doubt it. Reading comprehension would help you greatly dude.

How did you tear your shoulder? Too much hardcore circle-jerk action on the NABR board and you got yourself all silly? Hey, you mentioned me 'having no life' because I post when I have downtime at work, so I figured you'd like a taste of your own medicine. Any other ridiculous childish nonsense you'd like to use to continue your internet bullshit? Are we ready to grow up yet? i.e. this extremely mature comment: nawzlaser

Regards,

 

[GoFastTSI]

I find it incredibly humorous that you're still salty from being banned from NABR. Gee, could attitude and lack of proper knowledge have lead to your banishment. GASP, probably not!!!!

 

[NosLaser]

...I find it incredibly humorous that you're still salty from being banned from NABR. Gee, could attitude and lack of proper knowledge have lead to your banishment. GASP, probably not!!!!...

Doesn't really bother me at all. Only reason why I mentioned NABR is because that's where the people arguing with me are from (and looky here! You're here now too! Coincidence?? ) And if you remember correctly, I got banned for standing up for myself, which they don't take kindly to over there. They expect people to lay down. Sorry, it's not in my nature. I talked it out with Dennis, and he even mentioned he would re-instate me at the time, however I decided it would be in all of our best interests if I didn't post there. So carry-on with the nonsense Joe...

Regards,

 

[doug]

Wow, this thead has "Lock Me" written all over it...

 

[GrocMax]

Originally posted by TheHater

The crowers are a direct copy of the HKS's and still dont compare when it comes to quality or performance.

Have you measured and plotted via cam software or plain old fashioned graph, either lobe profile mentioned?

I have, the examples I had aren't the same.

 

[Tevenor]

Could everyone hold on for 2 seconds. I just ran out of popcorn. The next batch is already in the microwave...

Edit: Ok. Popcorn is done. Please continue. This is better than anything on cable.

 

[NosLaser]

...Could everyone hold on for 2 seconds. I just ran out of popcorn. The next batch is already in the microwave...

Heh.. Sorry Tev.

Regards,

 

[NosLaser]

I want to give a quick apology to the board for participating in and contributing to the arguments in this thread. I shouldn't have gotten defensive so quickly and until this thread, I had been working on not doing that for some time (hell, even Nick Drake, rdrkt, and tev were co-existing with me in pretty fair harmony.) Regardless of my opinion, and the way that I feel, and whether or not I was angry, it doesn't need to be done here. I don't think I'm entirely ready to take back everything I said just yet, but I do apologize for any personal attacks I threw at people in this thread as they are uncalled for. If anyone whom I argued with in this thread has any comments, or would like to discuss it in a non-heated fashion so we can end this ONCE AND FOR ALL, then please feel free to email me at [email protected] Thank you.

Regards,

 

[NosLaser]

One more quick thing I wanted to add regarding the role cams play is this. On a turbocharged car, things work a little differently, and especially one with our engine design. I think the overall argument over different cams types gets out of hand way too easily where better and more useful discussions could be taking place. To the point, playing with valve overlap is one of the cool ways to make extra horsepower on a naturally aspirated engine, but on a boosted engine, you don't get to take advantage nearly as much of valve overlap since overlap isn't good for a turbo car. There goes one of the more important aspects of a camshaft right there. And due to our valvetrain design, there is only SO much lift you can have because of how tight the clearances are, etc. Perhaps that will be a better example of what I was trying to express by saying the cams in Shepperd's car are a very minor role in the grand scheme of things.

Regards,

 

[GrocMax]

Huh? Did I miss something? Where in my posts is there lack of proper English, and where is there non-factual information? I invite you both to eat sh!t because you have NOTHING to back it up..other than your internet toughguy bullcrap...once again, as usual. Instead of talking your usual bullsh*t, why don't you pull out some FACTS? Focking liberal women...

Why don't YOU do it internet jockey? Your ideals make me sick. You sit back with your arms folded across your chest, waving your hardon around on an internet forum about how nobody tests things, etc. but yet you won't step up to the plate and do it yourself. I didn't post power gains with either cam combo; I merely stated I had good luck with the Webs. My posts were pretty much entirely information on how things work, and why they work, not bashing or glorifying any cam setup. Since you decided to bring my name into your whole little 'bad info' pride parade, I went ahead and replied accordingly.

Ask and ye shall receive, Sir. Since you got all huffy ASSUMING I was pointing the finger entirely and only at you, I will now single you out. There was just as much drivel written by others, but you are more fun, and the popcorn is out.


http://www.dsmtuners.com/forums/showthread.php?postid=8542#post8542

The cams on a DSM are roller type hydraulic cams, which offer more lift for the same duration as flat tappet cams.

This is not true.

As an example, take a flat tappet cam, measure lift/duration with a flat tappet, throw in a roller tappet and the roller tappet will show significantly less duration. The initial contact point between the cam ramp and the flat tappet will be very close to the edge of the flat tappet, which will produce lift sooner than a roller, whose contact point will remain close to tappet centerline until well onto the flank. However, flat tappet cams are limited to how aggressive the ramp rate can be- at some point the edge of the tappet will dig into the cam lobe. Thus they came up with 'mushroom' tappets, which offer a larger bottom surface. Roller tappet doesn't have that limitation and the ramp can be more aggressive. Peak lift will remain the same for all. If you want to add duration and ramp rate to ANY cam in this application, make the roller a larger diameter.

Intake opening usually occurs before top dead center, and intake closing occurs after top dead center.

Now I know you intended to say "occurs after BDC".

The intake centerline is expressed in crankshaft degrees after top dead center (ATDC), and the exhaust centerline is expressed in crankshaft degrees before bottom dead center (BBDC).

Intended to say "before top dead center" for the exhaust.

Lobe seperation is the amount of crankshaft degrees between the intake centerline and the exhaust centerline that were aforementioned.

Lobe separation is always expressed in cam degrees, and is the only common cam term to be in cam degrees. For example your Web grinds are spec'd to 110/110, which is 220 CRANK degrees apart, but they are spec'd to a 110 lobe center. HKS 272/272 are spec'd at 105/111, which would be 105+111/2, or 108 lobe separation.

At idle, there is plenty of time for residual exhaust gases in the combustion chamber to enter the intake manifold when the intake valve opens BTDC. This affect is similar to how your EGR valve works (which hopefully you have blocked off by now ) This is the culprit for the unstable idle.

No, high overlap does more that that. Kills port flow at low speed, won't pull vacuum, large cycle to cycle differences in cylinder fill, fuel doesn't want to mix well especially cold. Once you reach an engine speed to where you get stable cylinder fill, idle straightens out. Blowdown clears the majority of exhaust at low speed, the rest gets pushed out. Charge contamination isn't a big issue (yet).

http://www.dsmtuners.com/forums/showthread.php?postid=163806#post163806

In a turbocharged car, you want as little valve overlap as possible. The reason for this is you have highly pressurized air going back the intake valve and entering the combustion chamber. When you have overlap, even at high engine speed, you have so much pressure that it can actually blow pressurized air out the exhaust valve causing two things; a loss of cylinder pressure, and it also cools down the turbo, both of which are very bad. What you can do to remedy ths situation for those of you taking notes, is slightly advance the intake cam, and retard the exhaust cam. What this will do is lessen valve overlap, and cause higher EGT's.

The whole point to overlap is to clear the chamber of exhaust by starting intake port flow, pushing the remainder out, and getting intake flow early helps cylinder fill. Same thing happens in 2 strokes. 'Short cicuiting' or blowing fresh A/F mix out of the exhaust isn't a big issue. Lowering cylinder (and exhaust port) pressure during the exhaust stroke is a good thing- the engine has fewer losses, and there is less charge contamination. The adjacent cylinder that is in power stroke doesn't have as much work consumed trying to push exhaust out. There will be periods during the cycle when the piston is pushing exhaust out, after blowdown.

Advancing the intake and retarding the exhaust ADDS overlap.

http://www.dsmtuners.com/forums/showthread.php?postid=164924#post164924

With retarding the cam timing, you are going to be reducing valve overlap, and creating a more violent explosion within the combustion chamber (therefore again not forcing cylinder pressure out of an exhaust valve) so in essence, you are going to be increasing combustion chamber temperatures.

Retarding or advancing both cams does nothing to increase or decrease overlap, just where it occurs. Retarding the intake alone would decrease overlap, at the expense of dynamic compression. Retarding the exhaust alone will increase overlap.

If, when you are saying " more violent explosion within the combustion chamber" you mean BMEP, retarding an intake cam will merely move peak BMEP up in the RPM band, and reduce average BMEP if you go too far.

"(therefore again not forcing cylinder pressure out of an exhaust valve)"

huh?

http://www.dsmtuners.com/forums/showthread.php?postid=165083#post165083

Just to recap, advance intake cam timing (also reduce overlap since it open early mean it close earlier too) and retard exhaust cam timing means have a more complete combustion in the chamber thus more efficient. This should reduce EGT instead...

Advancing the intake and retarding the exhaust increases overlap. Get it right.

Retarding the exhaust tends to reduce EGT a little bit because more combustion heat gets turned into work, but not much. Overdo it and you run into that little problem with complete scavenging.

I'm not going to get into a lot of the other drivel that was written, because I couldn't understand what you were trying to say, so here are the FACTUAL issues which can be measured and refuted without possibility of parole.

I hope this helps everyone get things straightened out, and thanks for playing.

Just keep your little circle jerk over on NABR or your AOL chat room or wherever you do it, and don't bring that bullshit over here to detract from those who actually want to LEARN about cars and not sit here and b*tch for hours on end about little details that don't matter anyway

Damn good advice. Buh-bye.

 

[FastRthenU]

Well this was ####ING POINT LESS. But some what funny non the less. I have learned a few things, but some how feel less intelligent. Oh well. Yes i would have to say that advancing the intake and retarding the exhasut side, would really not help in reducing overlap. you would basically have the same amount of overlap, just at a differnt time. But if you retard the intake side like GrocMax said then yes you would reduce the overlap.

thanks for clearing that up GrocMAx. When i read it, i thought the same thing

 

[GrocMax]

Advancing intake and/or retarding exhaust increases overlap, it reduces the lobe separation. Advancing or retarding both cams simutaneously does nothing to the amount of overlap, or lobe separation, just when it occurs during the cycle.

 

[DSSA]

Originally posted by FastRthenU
Well this was ####ING POINT LESS. But some what funny non the less. I have learned a few things, but some how feel less intelligent.

Scott tends to have that effect on people. Just when I start thinking I know a little bit about something, I end up having a discussion with him.

Makes me feel like I've been working on/tuning these cars for 8 months instead of 8 years.