Guys…need some advice on cam choice…... Any experience with LPE GT2-3 cam? It looks like nice specs for a “mild upgrade” and obviously the lingenfelter name…specs @.050, 207/ .571lift and 220/.578 on a 118.5 separation.(total dur 255/281). It’s going on a basically stock 00 a4. Upgrade will include longtubes/catback and a vararam. Thoughts? My goal is to get about 100ish extra ponies and maybe 75-100 lbft more, I think its doable without doing the heads…...next upgrade would be yank 3200 & 3:42 rear

 

 

wow....no responses...this is a surprise

 

I'm doing the full 430 HP build on my car from Lingenfelter. I would change the heads as well as the cam to obtain more gains.

 

That cam is way to mild to achieve any big #'s--especially with an A4(drivetrain loss on an A4 is at least 20%)
I would say an honest RWHP total with yout catback-cold air-Lt's and cam to be about 65 RWHP and that would have to be with a tune thrown in there too---The cam has a high lift but the duration is = to or smaller that a Z06 cam--and the LSA at 118.5 is way to mild--If you have no smog inspection--but would like a somwhat good idle--and more power--i would choose about a .224-.228 @ 112 LSA--still that will only net maybe another 20-25 RWHP.putting you at 85-90-Pretty tough to get 100 RWHP without heads and an A4

 

100 Hp with only a cam? Hmmm...If you're talking RWHP, I don't see that happening with the cam you mentioned. You're gonna have to get a much more aggressive cam. At least a 114 LSA, but probably a 112 would be better if you don't mind a lopey idle. Without new heads it might still be tough to get 100HP gains.

I would do heads/cam combo and you will definitely get 100+ gains.

 

thanks for the responses. I think I may go with the cartek 2x...looks like a lot of good results from some other posts. SOOO many choices...I do know I need to get atleast a 114 because I dont want a lot of Lope. Thanks for the responses

 

I thought long and hard about the GT2-3 cam before I pulled the trigger, but I wound up going bigger. That cam is good for somewhere in the neighborhood of 30whp by itself. You won't hit an additional 100whp with a small cam. I went with a 224/224 on a 112 and a set of ported 5.3 liter heads aiming for about 100whp over my baseline (which included a Vararam and Z06 Titanium catback).

I would strongly encourage you to devour everything you can on cams before you pull the trigger. Your comment on the LSA tells me you have some understanding, but need to read some more. LSA is not going to tell you anything without knowing the durations. You can have a huge cam with a 116LSA and have it lope like a dragster.

If you are concerned (as I was) about lope, OVERLAP is the huge key. LSA is one of the factors that determines overlap. The more overlap, the more lope. Overlap = (((Intake duration + Exhaust duration) / 4) - LSA) x 2. So, for the GT2-3, it's 207 + 220 = 427 / 4 = 106.75 - 118.5 = -11.75 * 2 = - 23.5.

My 224/224 on a 112 has the exact same overlap (and therefore lope) as a 230/234 on a 116 (just for an example). The LSA effects overlap, but it's not the only factor. Just remember to look at the cam as a whole, not just the LSA. If I had a nickle for every time I heard "This cam has a 114LSA, so it won't lope", I'd have a few bucks. Also, go to LS1tech.com and learn about dynamic compression ratio. There's so much more than peak numbers; understanding how cams work will give you a cam that performs the way you want it to. Good luck!

 

What is LSA?

 

Disclaimer: I am not a master mechanic or anything, but I have put tons of hours into reading everything I can on cams and have learned enough to be an informed buyer.

You aren't being sarcastic on me are you? Assuming you aren't, LSA is lobe separation angle, which tells you how far off (in degrees) the centerlines of the intake lobe and the exhaust lobe are separated. The smaller the number, the closer the two lobes are, and the more overlap there will be. A narrower LSA (and therefore more overlap) will yield a higher dynamic compression ratio because it results in an earlier intake valve closing, which allows the cylinder to start building compression earlier. From what I understand, this will give you better low-end torque. The flip side of the coin is overlap increases lope. I really didn't want a lopey idle, but the more I learned, the more I realized in order to get good low end without sacrificing too much on top, I'd have to settle for some lope.

C5Ken mentioned the Cartek 2x cam on a 114LSA. This cam would only leave you with -2 degrees of overlap, which is just a hair shy of my TSP 224R on a 112LSA, which has 0 degrees of overlap. Compared to the GT2-3 (-23.5 degrees of overlap), the Cartek 2x is just as lopey and obnoxious as my 224 on a 112.

 

i wasn't being sarcastic, im' a noob to the cam world.

How does lopy-ness affect performance at various engine speeds? I'm looking for extre umph at the bottom end from idle to around 3000rpm.

 

I could be wrong but I thought that the lower LSA resulted in a later intake valve closing event in relation to the opening of the exhaust valve. This would equate to greater cylinder scavenging because the overlap extends the time that both the intake and exhaust valves are open causing the escaping exhaust gasses to literally cause a vacuum in the cylinder at higher rpms allowing for greater volumetric efficency. This would produce better torque at the upper rpm range. Just guessing though.

 

KILLRB, how does advance ground into the cam affect overlap. Your's is the first cam discussion that was explained simply. I need simple.

 

My understanding is that dynamic compression is what is most significant for lower-end torque. If you consider the case of a constant LSA for an analysis, let's say 114, the bigger duration you go, the later your intake valve will close. This will lower your DCR (dynamic compression ratio), which will reduce torque down low. I BELIEVE (again, I'm no expert) that problem is reduced as rpm climbs due to scavneging and other factors, but I'm not that well versed in that aspect.

In my cam search, I found that the ever-popular 224/224 on a 112LSA has a beautiful torque curve, starting off very early, and not dropping off too badly at high rpm's. A wider LSA on the same cam would push the IVC later, and thus reduce DCR, which is why I think you see a more sluggish torque curve below 3,500rpm on the same cam on a 114LSA. Heads help with DCR, because you can build a higher static compression ratio (that's the advertised ratio that you hear when you see that the new Mustgang or whatever is 10.5:1 for example), which will increase your DCR. With new heads, you can bump the SCR up and get the same DCR with a larger cam, or a wider LSA.

To sum it all up, it seems to me that a nice, smooth idle (which comes from less overlap) tends to require valve event timings that either result in a more sluggish low-end with a nice peak (setup A), or a nice low-end with an earlier peak and a plummeting torque curve at high rpms. (setup B) I ran into a guy on LS1tech.com who made a nice small cam to run (setup B type) through exhaust manifolds that put out a super-flat torque curve that was awesome. He also had around a -8 overlap, so it sounded pretty stealthy. Unfortunately, in order to get the good DCR and low-end performance, his setup peaked pretty early, and he shifts around 6,000rpm, because the engine is losing steam pretty bad up high.

Go research on LS1tech.com, and take a look at various dyno graphs, and you'll see what I'm talking about. Forget peak #'s, and look at the torque curves. I used Adobe Illustrator to put a ton of graphs from different packages onto one dyno graph (all stretched to the same scale) so I could compare and contrast. It helped me a lot. When looking at the curves, figure your intake valve opening (IVO), closing (IVC), exhaust valve opening (EVO), and closing (EVC). I believe IVC and EVO are the two that matter the most for DCR. Go to LS1tech.com and compare graphs of different cams with different timing events. You'll find lots of posts by Patrick G and Predator talking about valve timing and torque curves. To figure IVO and EVO, use the following formula...

IVO = (Intake Duration / 2) - LSA - Advance.
EVO = IVO - Overlap - Exhaust duration + 180. This final # is the degrees before bottom dead center.
Note: Overlap equation is stated in my previous post.

Here's a pic of my cam vs. the same cam on a 114LSA (stock heads). Notice the peak hp is close, but that the 112LSA tends to have a nicer lowe-end...

 

You are catching me in an area I'm not 100% certain on...

Narrowing the LSA (without changing the advance) simultaneously pulls the intake lobe counterclockwise, and the exhaust lobe clockwise. Therefore, the IVC and EVO are being pulled farther apart from BDC, and therefore farther apart from each other. What effect this has on scavenging and high rpm performance is beyond me.

 

Hey, I can relate with you Zee... Advance doesn't have any effect on overlap. The relationship between the intake centerline (the exact center of the intake lobe) and the exhaust lobe centerline doesn't change unless the LSA does.

Advance is simply a way of changing the valve event timing. Think of it as simply rotating the cam a few degrees in the counterclockwise direction. The overlap of the cam is what it is; we're just moving all valve events up 4 degrees. So, for instance, on my cam, the 4 degrees of advance cause the intake valve opening to occur at 4 degrees before top dead center, instead of right at top dead center. Here's a cruddy drawing to represent my cam vs. the same grind with no advance. They are 100% identical, except the one with 4 degrees advance ground in is rotated 4 degrees counterclockwise. Notice that the intake valve opens at the exact same time the exhaust valve closes in both charts. That's because we didn't change the advance. Hope this helps...

 

Who makes the described cam (tr-224-112). I'm also looking at headers,u.d. pulley,vararam, LS6 intake,(and heads, If money allows.)
then 3200 stall w/ 3.42 gear

 

The cam to which you are referring is Thunder Racing's cam. It's basically the same specs as mine, except the lift is smaller; it's a .563 as opposed to my .581. I went with a higher lift because I went with higher flowing heads. The Texas Speed rep I talked to told me he would reccomend the lower lift for a cam-only application. Thunder Racing doesn't offer the grind yielding .581 lift, so if you want that lift, you'll have to have it custom ground on an XE-R lobe or buy from Texas Speed out of the box; I have their 224R, which is the XE-R grind with .581 lift.

If you are doing cam-only with that cam, I'd consider the TR224 on a 112, and you should be able to hit high 300's at the wheel with headers, vararam, an LS6 intake and underdrive pulley.

P.S. I have a sound clip of my cam if you want to hear how mild the lope is on the 224 through a Z06 Titanium catback.

 

I'm learning

 

Very Cool, Please post sound Clip. I have to tell you something. It's nice to come on here & Quickly be B.S.'d (by kilrb) into believing that's the cam for me. But since I'm lazy & truly believe That you dug in and read up on this matter. I'm going to take your word on it. Ha Ha. Again, nice reply, and i'll be picking your brain in the future!!! (If you don't mind.).........joe