ok i've got to be fair to LGM here....the Cartek cam "only" dyno is a bit peaky itself IMO. I was thinking it might be a bit stronger tq wise off idle to 3800, but it's really not according to the graph.




these cam only ls3 setups need gears real bad....almost reminds me of the graphs of my centrifugal s-trim '98 cobra. they go crazy in the upper rpms.

 

First, the NPP exhaust is closed for the softer areas of TQ in that graph. Perhaps pulling the fuse for testing would give a better picture. The LS3 heads are very tempermental with exhaust changes. Here is an example:

Dave's predictions on what would happen with my power level when I swapped headers wasnt on target. I dont want to get into a header war here but the low end you speak of here is exactly where my new headers (and not what is on the cam only car here), pulled up the mid and low rpm TQ disproportionately. I know there are people who say they dont make that difference but the ones who swapped and didnt gain are the ones who didnt retune after the swap. I tune to the max for everything and there is nothing more I can squeeze out of the car. When I swapped headers the tune drastically changed and the majority of the gains were then realized.

For those that dont know, I have the LS3 heads (also called L92's because they were used on the L92 escalade engine). Long ago guys were noting this dip in the TQ between 3k and 4k. It becomes more pronounced with larger cam sizes. The only cams that didnt have this dip used LG headers and a small cam. Dave at Cartek stated one possibility about the use of LG's with the LS3; the gains may be because of the lazy exhaust runner on the heads in stock form. Exhaust scavenging may contribute to the differences. My TQ curve with these heads is nearly 45-50rwtq higher at 3500-3800rpm. Thats up 30 more after swapping the headers. One might chalk it up to the match of parts that work well together.

Many parts dont show the strengths and weaknesses until they reach max performance cam sizes. One side note about the heads and calling the 2008 a cam only car; SLP has put the LS3 heads on a stock cammed LS2 and got 425rwhp/425rwtq to the wheels with the usual bolt-ons. The LS3 cammed car here is a head/cam car from the standpoint of the LS2. The only thing it is missing is a compression bump. The heads have an issue with reversion being that the intake runner is so high a flow and the exhaust side is restrictive.

I am willing to bet that if this cam is put it in C6DVL's car, the bottom end TQ will be shockingly higher due to the fact that he has the LG headers. If you port the LS3 heads and get the exhaust side to near 240cfm the headers wont make as big a difference. From my experience with the heads on my car and 2 cams, I think I am onto something here.

 

I've only seen a few graphs with cam changes, but all of them were suprisingly flat below 3600 despite different grinds being used. Is the LS3 intake design contributing to the torque curve being so flat below about 3600 rpm?

By "lazy" are you referring to the number of degrees between .006 and .05?

I noticed that the exhaust valve opens a bit later on the LS3 than some of the other LSx grinds. That typically helps low end torque. My guess is the aftermarket cams are opening the exhaust valve at least 5* earlier , even after accounting for faster ramps. EVO isn't a huge factor, but it may be contributing to the lack of low end torque on some of the cams.

 

Mmmm, Im having fun with LS3 cams today Ill post more tomorrow, or MAYBE later tonight

 

Thats the best looking wheels I've seen on any vette. Look forward to reading results.

 

I meant to type that the exhaust runner (not lobe) is lazy because it flows 190-195cfm. Typo is fixed. I wasnt talking about a cam. The exhaust runner needs all the help it can get and the exhaust on the car is therefore more a tempermental issue than on a head with proportional flow ratio...intake:exhaust.

 

Spin...will porting the exhaust port only be of any value without headers

 

Well said!

 

where's your times
NHRA95 read the list!! i guess the driver can make 6/10s difference in an ls2 auto over the next ls2 and 3/10s difference over a more powerful ls3 and 7/10s over the guy with 455 rwhp and beat a zo6 every time he raced i have ran sticks and ran pro and super pro for years with a street car. if you can drive a stick!! it can be very consistent. don't make excuses you run what you brung maybe my next will be a stick so i can show you. everything you stated power under the curve, torque, being able to put down the power, track conditions and da, all apply to an auto, and stick, that's where the driver comes in that's where the clutch and throttle technique shine i thought your dyno was 455 rwhp not 448 with no cam, cant wait to see NOSLO6 track times

 

Dennis, if someone shuts off the gas, you'd be in big trouble.

 

i could still push or pull it faster

 

Next time I say something stupid..............i will get a while to read da rules

Looking forward to the results!

 

Hi Guys,

I am going to start a new thread but I will just post up these two graphs and explain them in another thread.

Thanks

LG



Black 08 This is a G6X-3 Cam only in a slightly different version that we did to bring the torque up. As you can see, we did accomplish that by getting 470 rwtq while still keeping just over 500 rwhp.





This car has Stage 1 heads, meaning just a Competition Valve job and a touch up with a couple of 10ths more compression 11.3:1


Silver 08

 

Ok guys, I've had 3 e-mails about this thread so far. Try to keep the comments civil or the thread will be locked.
Thanks

 

UM, what? Shorter exhaust lobes? The cam has to allow for longer valves? You really have no idea how these things work do you?

Why embarass yourself like this.

OK, any cam will fit; flycutting in some cases though. The lifters take up the difference if the base circle is smaller with bigger grinds. You can get a longer pushrod if you want to restore the stock preload on really big cams. If you mill the heads you will not need longer pushrods with any huge cam.

 

You didn't check the specks of the ls-3 cam did you. Or read about!

 

Sure I did! but no specs on any cam matter with any valves! Lifters adjust for the preload! Now you look even dumber!

And so you know, so you dont keep embarassing yourself, the base circle is no different than the LS2 cam! But I know of no cam that wont work with this engine aside from huge duration requiring a flycut! Even if the base circle was super small, a longer pushrod would make all things perfect again and since its always best to use a hardened pushrod anyway, you can get the ones you need for your application (there's that word again)! I do hope you arent going to cheap out on the pushrods like you did on your headers!!!

 

Ok Spin ...... now he needs to know why hardened pushrods are necessary and I do not want to steal your thunder about the evils of valve float and its cause

 

I just noticed the change.