As I mentioned in a previous post, going with the 4 degrees advance is going to hurt your top end more than it will help your bottom end. See, the LS1 will make the most power EVERYWHERE with the proper intake closing point. Your cam (224/224 110LSA +4) has an intake closing point of 38 degrees ABDC. That's 6 degrees too late. Let me show you what I mean.
RPM HP (+4) HP (-2)
2000 150 140
3000 200 200
4000 275 277
5000 370 373
6000 410 415
6200 405 420
6400 395 415

Only below 3000 rpms will the +4 cam be better. The +4 cam will make peak power at around 5800, but don't be fooled...it won't necessarily be better than the -2 cam for very long. After about 3000 rpms, the -2 cam starts to pull away. The -2 cam will make peak power around 6100-6200 rpms.

 

Thanks so much PatrickG. Are you using Desktop Dyno or some other type of Computer Similated Dyno?

 

No, desktop dynos don't seem to show actual numbers from LS1s to well. My numbers are based on 4 years of testing and dozens of dynos from 4 different shops. After several years, you begin to find some tendancies with the LS1. Intake closing point is about the most critical element to cam timing and a 110LSA cam +4 is really messing with a successful formula. Seen it too many times. More power and torque below 3000 rpms. Less from 3000 and up. LS1s have a "sweet spot" where they like to have their intake valves closed for maximum power under the curve. This seems to be in the 44-46 degree ABDC range. Your cam on a -2 will fall right on 44 degrees ABDC closing point.

 

Thanks again, I am on the phone with comp right now trying to get that intake centerline changed. I'll let ya know how it turns out.

 

Damn comp bastard don't know anything. I just got off the phone with speed inc and they said that the cam had just been ground today <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" /> . Oh well, it is my fault. I guess I will just have to opp for an adjustable timing chain. How hard is it to degree a cam with the adjustable timing chain? Is it something like on click per 2 degrees? Thanks.

 

Screw it, just going to install the cam straight up and see what happens. Going to replace the timing chain though.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DailyAluminumBlock:
<strong>Damn comp bastard don't know anything</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You must have talked to the same Comp bastard I talked too.

Ever get a grind number on the cam?

 

Guys, as you know I just requested a 224/224 110lsa 565/565 with a 106 intake centerline (4 degrees advanced) xe-r grind cam. I am rethinking the intake centerline. I just spoke with a comp cams representative (which told me that right around now I am looking 3-4 weeks for a custom grind roller so I have time to change it) and he told me that if I am not going to be spinning 6500 regularly then the 106 will be great as it will make a ton of low end with the 110 lsa, even more so then my stock cam. My question to you is is there any benefit to making more power at 6500 vs 6000. It sounds to me that with the current selection it would benefit my 3.42s although I will not have 3.42s for ever. All of the 224 thunder cams (112lsa and 114lsa) have 4 degrees advance ground in. If I brought back the intake centerline to 108 degrees it would be the exact same as that of the 224 112lsa thunder cam. What do you think. This is on a stock headed car and I go to the track about once a month. Any suggestions on the intake centerline are appreciated.

P.S. I don't want to change the 110lsa so please don't suggest that. I would like to try something a little different, don't have to pass emmissions, and want a good thump. I also have ls1 edit.
_________________
01 Pewter Hurst M6 SS #1215
SLP Options: Chrome 10 Spoke Wheels, Dual Dual, SS Grill
My Options: Wheels: 17x9.5 17x11 zr1 replicas with nitto 555 fronts and 555 extreme drags
Mods: If it gives you horsepower and it doesn't touch oil, I've done it.
Wheels: ZR1s with nittos (315 in the back)

Yes, that pewter idiot screaming down the road was me!!

 

Of course MTI and Thunder Racing know what they're doing. Just remember though, 90% of their customers are not "hard core" racers who want every last hp they can get. By grinding cams at 4 degrees advance, they give their customers crisp throttle response down low and low peak hp rpm levels. This is all good...unless you want the most power under the curve you can find. If that's you, then you don't want a 224/224 cam to have an intake closing point of 38 degrees ABDC (like your cam). I've already told you what countless dyno runs and track ETs have already confirmed...on a 346 LS1, an intake closing point of 44-46 degrees ABDC is going to give you the best power at all rpms...PERIOD, end of report.

Go with your cam 4 degrees advanced if you want. It will still make good power. It just won't make the BEST power.

 

So exactly how can I make my TR224 .563 114 cam fall into the 44 degrees ABDC range. If I retard it 4 degrees ( 4 degrees advance built in ) will that be at 42 degrees ABDC? Need some help here. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

 

At 4 degrees retarded you will be at 44 ABDC.

To figure it out...

(DUR / 2) - (180 - ICL)

(224 / 2) - (180 - 112) = 44

 

Patrick, 2 Questions:

1) Is the 44 - 46 degrees intake theory independent of the exhaust duration? Most of the examples discussed have been single pattern. I'm thinking of a 226/230 115 and the formula spits out an I/C of 112 using 45 as a target. Does the longer exhaust duration effect this theory?

2) Is there a reason to target 44 versus 46? Does that shift the power band much or change the overall performance?

 

LOnSLO,

Your TR224/224 114 +4 cam has an intake closing point of 42 degrees ABDC. Not too bad. Retarding it 2-4 degrees will get you into that 44-46 degree window, but since you're already at 42 degrees, you may want to leave it alone.

Tim,

Here's how I calculate intake closing point:

(duration/2)+ (installed intake centerline)-180= intake closing point after bottom dead center (ABDC)
Take 224 duration, divide by 2 = 112
Add intake centerline (114LSA +4 advance) = 110 ICL
The sum = 222 degrees after TDC or 42 degrees ABDC

Ragtop,

The 44-46 degree ABDC intake closing point was found ideal based on the harmonics of the LS6 intake manifold, intake runner shape and volume of the cylinder head, and rpm range of a 346 ci LS1/LS6. It is independant of exhaust duration as long as you're keeping exhaust duration within +/- 6 degrees of the intake. Single pattern cams work well in most applicaitons and they sure do make for easy math. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

Your 226/230 115LSA +3 cam comes right in at 45 degrees ABDC, just as you outlined. For a little more peak performance that would work really well with a Pro Thruster converter, you could also consider a 226/230 113LSA +1 and still hit your 45 degree target. This is more along the lines of a cam that Judson would recommend. He thinks 113LSA is the best all-around LSA for drivability and performance. The extra overlap with the narrower LSA cam would probably work well with your killer exhaust. The 115LSA cam would have more of a stealth idle and would be a little more emissions friendly.

The difference between 44 and 46 degrees is about 100-200 rpm in peak hp and torque. 44 degrees peaks at about 6200 and 46 degrees peaks about 6300 rpms. If you want your motor to make peak power at 6400, close it later, gator.

 

Patrick we use the same equation... I just didn't simplify it all the way. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Thanks Patrick <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
The 113 LSA was my first thought too, but I'm driving the car more for work now, so the old man 115 LSA may be what I need to do.

I did this LS1 Cam Advance / Retard Chart in Excel and it doesn't paste well, but for each cam size from 218 to 232 intake duration for LSAs of 110 - 115 here is what you want if you use this theory.
Advance / (Retard) to Be Ground In
Intake, LSA, 44 Degrees, 45 Degrees, 46 Degrees

218 110 (5) (6) (7)
218 111 (4) (5) (6)
218 112 (3) (4) (5)
218 113 (2) (3) (4)
218 114 (1) (2) (3)
218 115 0 (1) (2)

220 110 (4) (5) (6)
220 111 (3) (4) (5)
220 112 (2) (3) (4)
220 113 (1) (2) (3)
220 114 0 (1) (2)
220 115 1 0 (1)

222 110 (3) (4) (5)
222 111 (2) (3) (4)
222 112 (1) (2) (3)
222 113 0 (1) (2)
222 114 1 0 (1)
222 115 2 1 0

224 110 (2) (3) (4)
224 111 (1) (2) (3)
224 112 0 (1) (2)
224 113 1 0 (1)
224 114 2 1 0
224 115 3 2 1

226 110 (1) (2) (3)
226 111 0 (1) (2)
226 112 1 0 (1)
226 113 2 1 0
226 114 3 2 1
226 115 4 3 2

228 110 0 (1) (2)
228 111 1 0 (1)
228 112 2 1 0
228 113 3 2 1
228 114 4 3 2
228 115 5 4 3

230 110 1 0 (1)
230 111 2 1 0
230 112 3 2 1
230 113 4 3 2
230 114 5 4 3
230 115 6 5 4

232 110 2 1 0
232 111 3 2 1
232 112 4 3 2
232 113 5 4 3
232 114 6 5 4
232 115 7 6 5

<small>[ November 27, 2002, 09:55 PM: Message edited by: Ragtop 99 ]</small>

 

Hey Patrick, one more question for ya. If going with a 106 intake centerline is too early a closing point for my intake valve how come all of the popular 224 cams that have made 400 rwhp on stock headed cars have had an intake centerline of 108(4 degrees advance), only 2 degrees less then mine. I am inclined to think that Thunder and MTI know what they are doing when desiging a cam for the ls1. Will it be affected by the earlier power band of the 110lsa? Thanks.

 

How hard would it be to get a cam like a 226/230 113LSA +1 to pass emissions? Any idea?

 

PE,

pretty tough if you're on the sniffer.. not so bad if not. just find a good shop and you'll be fine.

BTW, this is a GREAT thread, lots of good info.

 

I think this is some very good information, but I think there is more to it than just getting the highest possible hp and trap speed. Yes I agree with what Patrick is saying about intake closing points but I dont think its right for everyone. I dont think its worth retarding a cam on a street motor just to get the intake valve closing at a certain point. I think you would be better off widening the lobe separation and maybe going with a +2 to get it a little closer. Or, you could just go with a little more duration. But honestly I dont think its worth giving up the throttle response on the street for a few more hp up top. Theres a reason why ALL the cam makers grind at least a couple degrees advance into there cams. It makes the car funner to drive because it wont feel mushy in the lower rpms. I agree that to get peak power having the cam at 0 or even retarding it will do the trick at the track and on the dyno, but it wont be as fun to drive on the street.

Chris

<small>[ November 28, 2002, 02:16 AM: Message edited by: CW 99 Z ]</small>

 

This may be a stupid question, but does degreeing a cam in "straight up" negate the advance that has been ground in to the cam by the manufacturer, meaning the cam is only advanced if installed dot to dot?

For example, +4 vs 0. All seperation between timing events remain the same...but in a cam with more ground in advance(+4), all the events will occur 4deg. sooner.

Thanks,

Mike