Well, I've read all of the cam guides, I've done search after search, and I've generally gone into information overload trying to figure out what cam specs would be good for my setup. I currently have a stock cube LS1 with PRC stage 2.5 heads (5.3L, Race port, ~63CC chambers, 2.04, 1.575 valves, stock MLS gaskets), a FAST 90 intake and 90MM TB, TSP T2 cam (232/234 .595/.598 @.050 112 LSA with no advance), 1 7/8" Kooks headers, UD Pulley, and 3600 Stall.

I recently dynoed 396/350 with the converter unlocked. I was happy with my peak numbers overall, but I feel like my car is really lacking in the low end. I am not even at 300ft Lbs until 4200 RPM and don't make it to 300HP until 4700 RPM. After wading through the DCR worksheet, and I'm sure I screwed THAT up, I kinda get the impression that my SCR is around 10.5:1 and my DCR is ~7.6 -ish.

Is there a cam that I can swap in that will get my DCR up in the ~8.3-8.5 range to help my lowend out, without giving up too much of my top end? I've seen some dyno sheets with a MUCH better curve than mine with even higher peak numbers, but I think most of those were on ~59 CC milled heads and a much higher compression ratio. I'm sure I should really just be calling a Patrick-G, or another custom cam guru, but I'd really like to understand what I'm asking for before shelling out a bunch of money on a custom cam.

I guess in the end, my car is a daily driven street car and only sees the track 3 or 4 times a year, so I'd rather have some great lowend and give up some top if necessary. But, I think the "Right" cam may get me where I want to be all the way around. For the record, I'm not OVERLY picky about street manners, but I don't want to get ridiculous.

Hopefully I didn't bore anyone to tears. Thanks in advance.

Eric

 

Prices are $450 for a custom cam tailored to your application vs. $380 for an off-the-shelf grind. It is not that much more money.

FWIW, I was told by Patrick G that the difference between a 236/242 112 LSA and a 228/232 112 LSA is only about 10 rwhp on the top-end. Not sure if this is what your looking for, but I hope it helps.

 

I bought a custom ground comp for $350 shipped. They don't cost you any more than an off the shelf grind if you know what specs you want and order it that way.

You have the tools you need to figure it out and are on the right path. I was in the same boat, and spent countless hours researching this, but I'm certainly no expert on the matter. First, how thick are your gaskets? If your SCR is really 10.5, you will probably need to get this up a bit to get the results you are looking for. Then you can spec out a cam with target valve events and DCR.

 

thinner head gaskets might help.

 

Yeah....been kicking myself for a month now over that one. That's what I get for not thoroughly researching the parts I bought before I installed them.

I may end up taking the heads off again just for this purpose (and maybe a teeny weeny bit of milling), if I can't find a grind that will get me to where I want to be.

 

the way you sit now is 10.79scr/8.04dcr
if you go to a .04 cometic you get 11.21/8.34
if you also do a small mill to get 61cc you get 11.51/8.56

I would try to get the compression up before swaping cams.

 

Thanks for checking and correcting my math. There were a few fields in the spreadsheet I used that I didn't know the correct values for.

As for getting the compression up, if you'd done as many head swaps as I've done this year, between my car, the wife's car and my last GTO before this one, you'd be more interested in swapping cams than taking the heads off again too.

Of course, I wouldn't need to pull the crank pulley off to just yank the heads off and clean them up and swap gaskets.....hmmmmm. Food for thought.