TheSamba.com :: View topic - * turbo * anyone have a tcs-20 cam card?

Thu Feb 04, 2010 5:38 am

miniman82 wrote: It's choking exhaust flow with less duration and lift, which makes no sense at all when you're trying to spool a turbine. That's what I don't like.

Have you actually used one? It works. There's no difficultly spooling the turbo. Scott Fetherolf had a 2276/TCS-20 setup that ran 10s, so you can definitely make the power with a TCS cam.

Thu Feb 04, 2010 7:46 am

So miniman should I call the guys at VW Paradise and have them pull out their bs turbo grind cam out of my motor? What would you suggest I put in, here are my specs:

82x94
comp e 46x40
9:1 comp
Garrett t3/t4 ballbearing
demon 750

street strip car

looking forward to see how much more power I can make with a "proper" cam.

And I thought 440 whp was good at 20 lbs.

Thu Feb 04, 2010 9:51 am

gbaker wrote: So miniman what would you suggest I put in?

What do you have in it now?

Thu Feb 04, 2010 12:04 pm

miniman82 wrote: I don't care about the LSA in this discussion. I've been telling people I personally like the tight 107 of CB's cams forever, but that's not what I'm getting at here. It's choking exhaust flow with less duration and lift, which makes no sense at all when you're trying to spool a turbine. That's what I don't like.

Mini, the difference between the intake and exhaust is not really that much in the first place. The TSC20 is just a 120 on the intake and a 110 on the exhaust.

The theory is that less exhaust duration keeps the pressurized intake charge from blowing through the head when both valves are open. Keeps the exhaust temp higher and is more efficient, You don't choke the exhaust because the exhaust is being pushed out by the pressurized intake charge from your turbo. You'd be right if this was NA, but with a turbo the intake charge will go right out the exhaust as it's the easiest path of flow. The smaller duration exhaust also helps the motor make more torque when off boost to help spool, the opposite of what your 107 LC does. Nothing against CB, but go racing and see what cams are being used, you'll see Engle and WEB 90% of the time. Why, they have results from 10's of thousands of combos.

I know you don't like it, but it works.

Thu Feb 04, 2010 1:44 pm

miniman82 wrote: gbaker wrote: So miniman what would you suggest I put in?

What do you have in it now?

TCS-20

Thu Feb 04, 2010 3:07 pm

You guys don't have to tell me I'm the minority with my rationale here, I already know that. :wink:

But you're also not telling me anything I haven't heard 500 times before from 500 different people. The whole 'blowing fuel out the tailpipe because I'm on boost' thinking is the oldest misconception out there; it's older than you and I, and the internet itself. Trust me when I say, we're not the first to have this discussion.

It's the reason some people put short cams on turbo engines, and maybe even the reason for the existance of 'turbo cams' in the first place. It all goes back to compression ratio, since how smooth the engine runs is more or less linked to duration, headflow, and the combo of compression and cam you choose.

If you pick a low compression ratio, the normal wisdom is for duration to take a hit because low compression will cause erratic low speed running. Most VW people don't really care about this though, so you see a lot of 300+ degree cams with low compression which tick over like a hit and miss. It's especially bad with draw through, since it causes a vicious cycle of low vacuum and erratic fuel metering. It's also why you see these funky grinds.

My method has always been to try and pick a combination that runs very well when N/A, so it has good low speed characteristics, then lay on the boost. I like to keep the LCA tight, because it tends to keep the engine very responsive. You might say I like a 'peaky' engine, but it doesn't drive like that at all. EFI is the reason for most of that, my combos would run very differently were they draw through.

BTW: fuel 'blows' out the exhaust of N/A engines during overlap as well; it's supposed to, it's what people are after with extractor exhausts- the 'scavenging' effect. But you don't see anyone putting short exhaust duration cams in N/A engines do you? 8)

I guess I get the feeling like this is a case of 'more than one way to skin the cat', which may or may not be true. After all, it's opinion. I have my way, you have yours. I don't like it, others have another view. :wink:

Thu Feb 04, 2010 3:11 pm

gbaker wrote: miniman82 wrote: gbaker wrote: So miniman what would you suggest I put in?

What do you have in it now?

TCS-20

I'm building almost the same thing right now, my cam of choice is CB grind 2288 (K-eight). Because you have 9:1 compression, it would still have decent idle if you use EFI. Draw through changes things slightly, if you like idle quality anyway.

Thu Feb 04, 2010 3:38 pm

miniman82 wrote: BTW: fuel 'blows' out the exhaust of N/A engines during overlap as well; it's supposed to, it's what people are after with extractor exhausts- the 'scavenging' effect. But you don't see anyone putting short exhaust duration cams in N/A engines do you? 8)

No, fuel is 'drawn' out the exhaust on a NA due to the scavenging effect of a good exhaust system. Fuel is 'blown' out on a turbo engine, the difference is why some believe different cam patterns are needed for NA vs. turbo.

Before you correct me, yes I'm aware NA engines can actually create a boost effect through the intake system due to extremely high efficiency of the design, but we are talking about VW's.

All theory aside, when the turbo starts making boost the cam becomes much less important than on a NA engine. I think this is why people have so many opinions, hard to tell what effect the cam has when you cram 15 psi into the head. I like a torqey cam to build the boost sooner. You yourself have claimed many times you get no boost in 1st gear, it's because you run a cam on 107LC and run very low compression. 112LC makes for a much more broad torque curve rather than being peaky.

I really like these types of discussions, I know I'm wrong most of the time and like hearing what others think. Let's stay cool and keep this going.

Thu Feb 04, 2010 6:55 pm

Turbo_Manx_Maniac wrote: No, fuel is 'drawn' out the exhaust on a NA due to the scavenging effect of a good exhaust system.

Same difference, if you ask me. People seem to think there's something wrong with having burning fuel in the exhaust (not saying you do), but the fact is every engine has this happening at some point. N/A engines have 14.7 lbs of pressure forcing the air in, turbos simply raise the pressure a little higher.

My position has always been that if there were some problem with it, you ought to have some kind of damage as a result. There isn't any. Some people like to cut off the exhaust guides, because they are afraid of melting them. Only thing that gets EGT high enough to melt bronze is a horrible tune or extreme boost pressures, neither of which I don't think are discussion points here.

One thing I've always been interested to do is compare my EGT logs with those of another turbo VW, just to see what other people run. Sadly, there aren't a lot of people with the need to know, or the inclination to share such knowledge.

If anyone in the Chicago area would like to know what their EGT's are doing, I'd be willing to hook my logger up just for kicks to see what's going on. This site has needed some quantitative data as a reference for as long as I've been here, so maybe it's time? Feel free to PM me, I'm willing to make it happen.

Quote: Before you correct me, yes I'm aware NA engines can actually create a boost effect through the intake system due to extremely high efficiency of the design, but we are talking about VW's.

VW's are not unique. Eric A. has logged positive manifold pressures with his N/A ITB race engine in Utah (higher than sea level), so it is very possible to have N/A 'boost'. And that's with a very long (non 'turbo') cam. :wink:

Quote: You yourself have claimed many times you get no boost in 1st gear, it's because you run a cam on 107LC and run very low compression.

You know I've been thinking about this lately, and I think I know why now. It's true I don't get much boost in 1st, but I've come to the conclusion that it's a function of gearing and a weak wastegate spring. Reason being is if I disconnect the boost controller, I get the same boost in all gears (about 3 lbs) no matter how I drive. My turbo comes from a Saab, so I have no way of knowing what spring it actually has in it. Since I have a 4.12 final, 1st simply doesn't load the engine enough to build boost. As soon as I shift, it's game over and I can get whatever I dial in for any other gear. Could be my TB isn't opening all the way too, I haven't really fooled with it much in the cold months.

Fri Feb 05, 2010 6:22 am

enough of the can rattlin' .... any real world results of hp and track times with this cam?

Fri Feb 05, 2010 7:02 am

loudaddy wrote: enough of the can rattlin' .... any real world results of hp and track times with this cam?

MinamiKotaro wrote: Scott Fetherolf had a 2276/TCS-20 setup that ran 10s .

Who knows why Engle chose to grind the TCS20 as a split duration cam; maybe the folks who were turbocharging engines at the time were doing so in lieu of head work. Stock heads, where the exhaust is a bit large for its own good to begin with, would probably benefit from the lesser exhaust duration.

In any case, seems some folks have used this cam and gone fast. Heck, folks have pushed stock, unported heads into the 10's with a turbo. I doubt you'll have a problem with this cam.

Fri Feb 05, 2010 8:59 am

Don't you think it's backpressure related?

If your turbo is too small, you will have a lot more bakpressure than boost, so it's better to have small exhaust duration, because it's better to close the valve earlier to avoid exhaust gasses to return in the cylinder, no?
If you have a well matched turbo, may be you don't need a split duration camshaft. My tought.