gtodoug

great thread guys. I am in the market for a cam for my ls3 GXP so I am listening....

SpinMonster

I used 228 cams with those heads quite a bit and they all seem to land in the 480rwhp range with a best of 482. Once you limit the ex duration, there isnt any reason to stay small on the intake siude for overlap's sake. A

Without exception, porting lost some TQ in the midband for the whopping 6HP it gains at peak. You will gain 15hp and 20+rwtq from the 1 point compression bump and 10rwhp from a competition valve job. Keep in mind that aftermarket valves will eat up P/V clearance and you will need to check to see if you need a fly-cut. I would stay cam only before shrinking the cam to avoid doing a proper install.

For those that dont mind the more agressing lobe, the LSL lobe on the intake side will be a better cam:
230LSL/234XER 114+2. Lift on the intake side will be in the .62x range.

This and lots of info is in this thread:
http://forums.corvetteforum.com/c6-t...cam-specs.html

SpinMonster

If you want to try a bigger cam, please PM me. I'm not sharing the specs yet.

vertC6

Thats a great write up I enjoyed reading that! How do you calculate if you need to fly cut your pistons with any given setup? I know each cam is slightly different in actual durations and lobes from what they advertise. If I were to mill the heads lets say .010 and go with a .040 HG and use lets say a 225/230 .612 on a 116? Is there a specfic way to measure or foumula?

SpinMonster

That would likely not need a flycut.

You would clay the pistons to check. You are going to be 20HP shy of a great driving 230 cam by not going with a proven cam. Do not install a grind you didnt see used before.

The 230LSL/234XER 114+2 will outperform the 225 cam even with the compression bump so I would tell you to do the 230 cam and dont remove the heads. You will make more power at all rpms over a 225/230. A 224/230 115 has done only 475-480rwhp on two cars I know of, so I doubt yours will be any different. A 230/225 will drive exactly the same and break 490rwhp over your 225/230. Why arent you willing to just install what you know works. You arent going to beat it with a single guess.

Use 1 3/4 headers with this cam.

vertC6

No I understand I just want something a little milder than the 230/234, I have heard several of the clips and I simply don't want that much lope. The biggest I would go would be 228/232 116lsa. I would like to bump the CR and at least clean up the exhaust side to add a little extra flow, but I am concerned about fly cutting, I assume it is done with a special tool and is it tough to do?

How thin of a layer of clay do you put on the piston to check PVC, and what is considered a "safe" spread?

I assume the 1 3/4 headers are for tq?

Merry Christmas and thanks for the advice.

vertC6

Also is a 228/232 fesible on a 117+2 with 11.5:1 SCR and 8.6 DCR?

jmudreamvette

Spin, I am doing a cam next year. I have an 08 with Z06 manifolds & cats with NPP, Ported TB & intake, Vararam,A6 trans. I have seen results on your 230/234 cam, everyonewho has it has loved it! I want a cam with no surging with the A6, and I think that cam will fit the ticket. Is it worth $pending the money for headers for 10-15 more HP? I want the best bang for my buck...thank you for all your information on this forum, You are a class act.

8850

Spin, would this cam work with an 08 automatic, stock converter? How low will it idle?

HC Mechanic

This has lope:

http://www.youtube.com/watch?v=DBmFS...ayer_embedded#

vertC6

Oh I have heard it, it sounds great but just a little more than I want for around town.

SpinMonster

Flycutting was covered in the thread I posted a link to for you.

A 228 116 will not fit with 11.8 (8.7 DCR for that IVC point). A 228 on a 116 peaks higher than the intake manifold forces the peak on. A 114 is going to be a better LSA without lowering DCR even more. Tighter increases DCR.

You arent going to 'help' flow by opening up the ex port; you will lower velocity. The 230/234 will make 20rwhp more with a valve job and more compression. 15 of that comes from compression.

Even a 224 cam has a chop to it. I think you need to find a cammed car you like and use that cam. I came up with this one because it was mild and drives with no driveability artifact. Personally I think you should install it and not flycut. It will beat the other cams that are smaller even if you go through the expense of increasing compression. The biggest cam that fits with an 8.7 DCR will be a 224 cam. A 228 on a 116 or 117 will not fit with 11.5 static compression you propose.

Anyway, I posted to share factual info based on a lot of installed cams and to put a stop to the rumor mill on big ex duration. I'm not going to redsign entire cam profiles here but based on your questions, big exhaust duration cams like the ones in that test had the same overlap as my cam (or lots more in some cases) and would run with even more chop if they had more ex duration. That alone would have predicated you to not use such big splits....they have lots of lope from overlap.

SpinMonster

224XFI/224 XFI 115+2 @700rpm with a good tune.

The 230 will be too high an idle.

SpinMonster

You will need a higher stall to run this cam.

Yes headers are worth it. Running the G6X3 with Z06 maqnifolds was tested against the LG headers and it was big HP gained....40rwhp.

http://forums.corvetteforum.com/c6-t...uper-pros.html

Use a 224LXFI/224XFI 115+2 with the stock converter for lower rpm.

vertC6

I understand you covered fly cutting but what I meant is how it is actually done. I have never seen it done before but I found it on the other forum on how the tool works and how it is cut. I assume that when you fly cut you use the exact heads that you are going to use (already milled) to flycut, I saw were you (and the other guy) used the blue tape to keep the engine clean. So if I understand right you add in the HG depth to figure out how deep to cut into the piston needs to be without the HG actually being on while cutting?

So when you measure PTV is there a "magic number" for clearance that is considered safe? I assume you install the cam, heads, pushrods, and HG you plan to use and then do the clay test for depth.

vertC6

"The last cam I had was a 228/232 and it was stronger in the mid-band. These are very small differences but a man knows his ‘tool’. Duration takes away from P/V clearance too as it grows. I wouldnt be a bit surprised if a 226/230 or a 226/232 would do as good or better than this cam did. Data from various sources suggests that smaller works better on this head."

You had made this quote in the same write up, have you ever tested the 226/230 in an LS2/3?

vertC6

Sorry one other thing what about the exhaust valve side. I saw where the other guy cut that side too, do you cut yours on your cam setup? I wasn't sure where the exhaust valve and TDC cam into play. Thanks

SpinMonster

At the time of that install there was no such thing as an XFI or LSL lobe. The XFI lobes go from 224 to 230 on the next biggest lobe. There is no 226 XFI lobe. Smaller in that case didnt mean 226/230 over a 230/234 and it will not make as good power as a 230/234. It referred to overlap limitations. It meant smaller at 228/232 rather than a 236/242 112LSA worked better and referred more to exhaust split size as I already discussed. I think smaller exhaust was more a contribution to that statement than just intake which is what you seem to be fixxed on. I like a 230/224 before a 230/242....for driveabilty. The 230XFI enabled the 230 to beat the 228XER I used on Craig's car.

You seem insistant to use a smaller intake lobe so go try it. I think its because you read from other cam designers that smaller intake will make more power and you dont beleive the overlap is the governing rule here. If you did and really wanted to limit overlap with a lower overlap cam, you would lower ex duration to do it. The next smaller cam I recommend is a 230XFI/230XFI 115+2 and even that will beat a 226/230 XER cam. A 227LSL/231 114+1 will match the 230XFI/234 XER 115+2. It isnt the shoter int duration that makes it match the performance but rather that the lift on the lobe passes more air at lower lift values.

I think an LSL lobe like a 227 LSL lobe on a 114 or 115+2 will work as good as mine but it has more aggressive lobes with more lift. Not everyone wants to tax a spring like that. Using a spring with .650 lift potential along with hardened seats that are .060" thick is dangerous on LSL lobes because it makes the installed heights about 1.74" on a stock head. This along with the actual lift from 1.7 rockers gets you really close to spring bind. I think this is more likely the reason timing chains are breaking than the UD pulley theories. Anyway LSL lobes are out of the question for me unless you do a competition valve job which gets more installed height by moving the installed valve away from the piston. A LSK 234/234XER 115+2 is also a 4 degree overlap cam with crazy lift on the intake side (.64x). That will make 515 cam only. Drves great but the spring better be top shelf.

On 6.2 liter engines, you will lose midband TQ from a ported head and I tried it as other tuners did who shared this info with me. Ported heads do gain back some from milling due to increased compression and the valve job so it hides the losses from porting. A 260cc runner is already too big for only 330cfm. Porting it out to 275cc's to get 20cfm is rediculous. I know I would get flamed for typing this but I know of two tuners that found this to be true and it was discussed on the phone. I swore to not say what tuners or what CNC heads.

You DO NOT use a good head to fly-cut. You cant. Both of these threads clearly indicate that the cutter is bigger than the actual valve and therefore requires you to cut the head's intake seats out.

The Intake valve needs fly-cutting because it uses a HUGE 2.16 valve. The ex valve isnt huge in that sense and thus fits fine with just about anything you want to use duration wise without fly-cutting. A 242 ex duration would need to fly-cut so why cut into a piston if you dont need it. The releifs you cut in will decrease the compression which is hard enough to get back up on these heads. You will really have a hard time getting compression high enough using these heads. I doubt you will be able to hit a static compression of 11.7.

Fly-cutting isnt a beginner's project and I dont recommend you doing this based on your questions.

Here is another fly-cut thread from a car I did in MD. It may have some more info you need to seek.

http://forums.corvetteforum.com/c6-t...mpression.html

vertC6

I promise I won't port the heads, I believe you. Milling and valve job only! and yes I have read the threads regarding smaller intake Dur. and some points are valid but I feel your cam designs have shown the optimal range of hp and tq. throughout the rpm range.

I don't know if you saw this and I am not sure if I am allowed to post this but this "Lindy Tool" is supposed to be custom made to fit your specified head and valve seat. "Radial clearance built into the cutter, typically .090" is what this guy quoted. Here are some pictures, have you seen this before?

http://www.ls1tech.com/forums/genera...ing-tools.html

I am with you though, I want to build the motor to fit my cam needs and if that means fly cutting I am definitely willing to do so because I want the higher CR for driveablity as much as hp and tq.

Thank you again for spending the time answering my thousand question thread, "once I get going I have a hard time turning it off''. And FYI I have been building motors and working on cars now for 15 years I just had never seen fly cutting done before, from what I have read and taking my time I think it is something I can do with no problem, and hell its only a 50k car!!

vertC6

Also if you look closely at the tool you can see the blades go outside the intended valve diameter.