but I've got to ask one.

I'm looking for something similar to the CheaTR cam without the higher valve lifts of the CheaTR. My car is a 2005 GTO LS2 with stock intake and stock exhaust manifolds. Not ready to change either of those at this point, since TT may be in the future of the car. Currently running an A4 with a 3000 stall and spraying a 100 dry shot at the strip.

Using the CheaTR and the stock LS7 cam specs as a starting point, I am considering the following cam as an option.

216/232... .561/.575...LSA 116 +3* advance (Comp XE lobes)

0.006 0.050 0.200
Intake Duration - ID (first number) 269 216 135
Exhaust Duration - ED (second number) 285 232 148
Lobe Center Angle - LCA (also known as LSA) 116 116 116
Intake Centerline - ICL 113 113 113

Intake Valve opens - IVO 21.5 -5 -45.5 BTDC (- indicates ATDC)
Intake Valve closes - IVC 67.5 41 0.5 ABDC
Exhaust Valve Opens - EVO 81.5 55 13 BBDC
Exhaust Valve Closes - EVC 23.5 -3 -45 ATDC (- indicates BTDC)
Exhaust Centerline - ECL 119 119 119
Overlap 45 -8 -90.5 degrees

DCR 8.51:1

The XE lobes are not as aggressive as those used by TR on the CheaTR; and the lift (especially the intake) is lower. I am willing to give up some performance for the increased (hopefully) reliability of the valve train. My problem (and question) is that I have no feel for how much I might be leaving on the table when compared to the real CheaTR. If any of you cam gurus can comment on this, I would really appreciate it.

 

First off, the CheaTR is not known for being hard on valvetrain provided you have the proper spring selection. Secondly, the XE lobes will still make good power, but you probably don't want to run a 116LSA +3 advance. While the extra advance will close the intake valve earlier (which will pump up dynamic compression), it will also open the exhaust valve much ealier (which has the potential to soften up your torque by bleeding off some of the compression stroke). Since the CheaTR is 117LSA +1 and is a proven performer, you may want to consider running your cam 116 +0 or 116 +1. The later IVC and later EVO should help make more power in an LS2.

 

I have used the Cheater cam quite a few times and I worked with Geoff on the Cheater plus for the LS2 guys. In fact we were the first company to try it, use it, and report the results and afterwards TR added it to the site.
I will say the results speak for themselves. The cam flat out works. We have used the cheater a couple times and the LS2 cheater a few times now. With a Patriot Extreme Spring kit the package has been a huge success. Very quiet, stealthy, and all around a great performer.
IMO I would use that cam if that is the style cam you’re looking for.

 

Thanks Patrick, I was hoping you might chime in on this one. As you probably surmised, I let my desired overlap determine the LSA; and then cranked in 3* of advance to achieve a DCR of ~8.5:1. I noticed the effect on valve events which you pointed out; but, quite honestly, had no feel for how much effect the VE changes would make. I understand the relationship and effect of juggling VEs; but don't have the experience to quantify the "how much" factor when making those changes. I'm glad there are guys like you around to keep guys like me out of trouble.

I haven't totally ruled out the LS2 CheaTR as my final choice. As you pointed out, it is a known success...and that is a huge factor. There are only two things that have stopped me from ordering it already. First, I am concerned about the lift and the aggressiveness of the lobes. I guess it is hard to teach an old dog new tricks; but when I see a lobe over .600" of lift, a caution flag pops up in my mind. I can probably get over this if I keep reading your (and Patrick's) post enough times.

The second thing that is a little troubling to me is the 6800 rpm peak power range. My transmission is a 4l60e and I really don't feel comfortable revving past 6200-6300 rpm. I just keep thinking that the extra 500-600 rpm at the upper range of the CheaTR is wasted to me; and that I might get better overall results with a cam that peaks earlier to better take advantage of my shift points. My goals aren't to build a world beater; but I do want to get full benefits from whatever I choose.

I found the Patriot extremes on your web site. I am assuming that I would have to get the CheaTR from TR if I chose to go that route. Since you have used the LS2 CheaTR, would you happen to have the duration specs at 0.006" and 0.200"? I have those specs for the LS1 version of the CheaTR; but can't find them for the newer cam. If the specs aren't classified information, I would appreciate it if you could either post them here or send them to me in a PM.

Thanks again to both of you for the replies.
John

 

I hear you on the old dog new tricks thing. LOL
It happened to me as well I was so used to the XER lobes when the XFI and the LSK stuff came along I was pretty much like
but then I started playing with number's saw TR using the LSK on the TRak cam and figured I would try it myself. So far so good as we have used about 15-20 LSK/XFI based cams now and the results have been great. A huge amount better then the XER stuff? No, but for some reason that Cheater 2 cam has found a special place in my heart.
You can order the cam through TR or from us. That is completely up to you. Both of us also carry the Patriot spring kits. We work with TR ourselves from time to time and I think you will be very happy with either shop.

Just so happens I have the cam in stock and therefore have the cam specs very handy.
.006 265/279
Valve Timing @.050 Open Int 8- Exhaust 53 Close Intake 43 ABDC Exhaust 3- ATDC

 

Thanks for the specs. Looks like the DCR on my application would be 8.43:1 which is very close to the 8:5 I wanted.

Any problems with PTVC on the installs you have done on LS2 engines with stock top end? I would prefer not to cut reliefs in the pistons since I will be spraying the engine.

 

Man it isn't even close on P/V clearence. Plenty left over.
In fact one customer on ethe internet we sold this kit to with a set of 62cc LS6 heads and a .045 gasket and he had no problems. As far as I know nobody knows he even has the cam still 3 months after the install.

 

how would the ls2 cheater work with a ls7 block, 4.0 stroke, l92/l76 setup?

 

How well a cam will work in a setup all depends on your goals, however I would be 100% sure there is a much better cam for that setup no matter what goals you have.

You would have 420+ cubic inches with that setup probally more compression, better exhaust etc etc etc. That setup is where you get yourself into a custom grind area.

 

this is where I start to struggle, being in the UK, there is very little experience with the ls engines, and even less with cams and custom cams for them.

I am looking to get to 427, ls7 block, stock bore 4.0 stroke, unmilled, unported l92/l76 NW 90mm tb, 600 lift max, emmissions and cats ( though fairly relaxed ), 1 7/8long tubes, 3 inch exhausts to rear, t56, 3.23 rear, 1900 lb all in weight,f ast road/occasional track, no drag strip, a little lope but not so much I cant see where I'm going when i'm at the lights, plenty of low down torque, less interested in max hp. 11:1 compression, 95 octane is no problem for me in the uk.

no plans for power adder,

the block, heads l76, crank, rods are all in. pistons and fine detail still to be decided. This is still going together on paper at the moment, so fine tuning on the assembly is being done, probably -4cc reliefs on the pistons, gasket thickness TBD, quench TBD....

I am open to any suggestions from people that have done this or have an input

p.s. sorry to hijack this thread, mods, feel free to move!!##

 

SPG,i would look into cam selections falling into the split durations starting in the 220's @.050 with 8-12*split and actually getting into the 6 teens if not more for the lift area on say a 112-114.the l92 heads have shown some great flows without sacrificing port velocity and a cam in those area's will greatly increase the efficiency of those heads you have allready chosen.Lingenfelter has some nice lsk cam profiles that may fit what you are looking for.
Good luck.

 

You should be aware that the 95 octane rating in the UK correspondes to 90 in the USA. Try 98 or 100 octane as rated in europe and the UK.

I have a shop in cologne, and tune a lot of Cobra replicas with LSx engines on my dyno. Contact me if you like: +49-221-933139-13

Till

 

Till

didnt know that the octane value was different. i use 98 all the time in the cob. would be interested in your thiughts, where are you based? perhaps i might pass by next time i take cob to norsdschleif