ive been toying around with i few ideas and i want a cam only lt1, stock heads full bolt on car, but i want to get the most hoarse power out of stock bottom end and heads.

-i am looking for the largest shelf cam i can get bigger than the gm847
-would a custom grind cam benefit me over the shelf cam much?

-any suggestions on cams would be great

honestly im looking to get around 360plus RWHP.

 

I don't think it's possible to get 360 r whp without porting the heads. I would say custom gring is always better. Good luck.

 

The typical "big" cam would not be the right chopice for max hp from stock heads. Your stock heads will stop flowing at about 0.500 lift. So, there isn't much point in lifting past that. But you do want to get the valve open as quickly as possible to the desired max lift point. You also don't want a cam with a late intake closing point as this will lower your dynamic compression too much. Big cams will have a late IVC event and thus need a higher static compression to work properly. You can't afford to do this with your stock compression.

A custom would work best, but you could try something like the following:
CC lobes #3109/3111 which are 220/230 @ 0.050" lift. Using 1.6:1 rockers on the intake and 1.5:1 on the exhaust nets .544/.560" lift. Have it ground on a 110 degree LSA.

Overall, ~400-425hp should be possible with stock heads if everything else is right. The would include a 58mm TB with matching intake. "Port matching" the intake and the heads. And a good set of headers along with a good tune, engine in good shape, etc. That would put you in the range of 340-360rwhp for an M6.

Rich

 

yea, i was trying to determine that, thanks for the help.

i have seen several cars that have broke the 360rwhp barrier with stock heads(do a search for gm847, i believe altjar put like 363-3 down with that cam)

i would definaely have a lt4 intake and a 58mm tbody coupled with some, kooks lt's and a eletric waterpump, should do the trick...

just seeing if and what kind of cam would or could do better than the gm847
by noy exceding the 600. lift

 

In hindsight, I would have opted for a custom cam considering the minimal
extra cost. You should seriously consider a custom cam, especially since
you are not doing the heads. I have talked via email with three of the custom
cam experts and all were extremely helpful and very nice to deal with. The
main reason I went with the Crane 227 is based on the recommendation from
one of the three that it's a very good cam for my setup.

 

If you can put it in your budget a custom cam and valvetrain is going to be the way to maximize your HP output. The GM 847 is a good cheap cam, but bigger is not always better for a cam. Going to big will loose mid range TQ which is going to be slower than taking a few HP off the top end and making a fat TQ curve. RPM always helps ET too so it's all about where you want to go and what you have to work with.

To add to a few peoples points here.....

First scrap the LT4 intake idea. Going with a LT1 intake with a square opening rather than the one with the port narrow at the top like a LT4 is a the best way to go for a non ported intake. That can be a big difference motor to motor so "cam only" can have variables.

A bigger TB is always nice if the tuning is going with it.

Kooks headers are VERY nice and will help the HP output of your car, that would definately be something to spend money on right there.

Electric waterpumps are also a good idea. Without a waterpump and aftermarket TB you can get the car to 355-360rwhp. Dyno Chart I honestly think that a hyd roller LT1 can do much more than that if you are going for that and want to do all the bolt on things.

Here's a good thread about that

Good points as always..... a lobe that's aggressive enough but matched to your RPM range is always the key.

Also balancing the dynamic compression ratio and piston to valve clearance is also a good idea. One of the reasons a custom cam can do for you where a off the shelf cam can't.

this is about the only point I don't agree on. Lifting the valve up more is always going to lower valve spring life which is Rich's point I would guess. You can find HP though opening the valve more and more even if the heads don't flow more the higher the valve is opened. Going to around .600" lift is still going to help and it's not going to kill the life of the valve springs. Plus if everything is done right it's even easier to control the valve when the duration, area and lift of the cam lobes are matched for the RPM range the motor runs in.

Guys with solid rollers have put down 380rwhp, and NHRA prepped "stock" motors with stock heads do 400rwhp or more. 370-380rwhp is doable on a stock head/bottom end setup if it's all done right.

Bret

 

great info man, thanks for the insight.keep in mind..
-the engine will be brand new, next to no miles
-i plan on spinning it to about 6600 rpm
-i think with a mild port on a lt4 intake and a as&m 58mm t-body would benefit over the lt1 intakem perhaps minamal, but may be necessary to achieve my

-who would you suggest talking to about getting a custom grind cam???

 

BTW:i am using a nice valvetrain kit, 1.6 comp pro rockers, dual titanium valvesprings, titanium reatainers, 10*locks, double roller timing chain, titanium valves, and im having lt1 edit by a great tuner here in tampa.

 

Bret's point is well taken. Unless you could open the valve instantaneously to the point where the port "stalls" you do want to open the valve past the stall point. In so doing, the duration at max flow will increase. When I re-read my statemtn I realize it's misleading. Instead of "there isn't much point in lifting past that" I meant to say "there isn't a point in lifting much past that". IOW, there is no benefit to going to much more than 50 or 100 thousanths past the stall point. Just wears stuff out faster.

Rich