I have a 99 LS1, I am going to install the LS6 intake, are the LS6 heads a good upgrade too? they are direct replacment?

 

yes, id have them ported and polish if ur going to go through the trouble of swapping heads.. i found them new for 500 from jakesperformance.com

not sure if theres cheaper for the 243 heads.. maybe someone will chime in

 

I was thinking about this too, but was wondering if you have to change the cam out, or will adding the heads alone be a nice difference or a waste.

 

The heads are going to be a waste if you don't add the cam. You'll see (maybe) 10HP at the wheels without the cam. If you're getting the heads directly off a Z06, you need to make sure you get the right cam for the right year of 243 heads. The valves and springs are different on the 2001 vs. the 2002+ because the cam was more aggressive in the 02's. If you get an 02+ head with the stock valve train, get the LS6 hot cam and you'll see significant gains. (You might want to upgrade your clutch at that point!)

 

You should definately go to a more aggressive cam if you are going to install ported LS6 heads. Ask who ever ports your heads what cam would work best with your heads.

 

Actually, no. A heads only upgrade is pretty good. I did it after installing LT headers. It added much more power than the LT headers, for me it was closer to 30hp. I dyno'ed an A4 at about 340 hp with ls6 intake, LT headers, ported 243 heads. When stock they ususally are 290 hp. When I added a cam I was dissapointed as the increase was less than the heads, but that could be because there are no good local tuners.

It is a smaller job than installing a cam, but adding a cam is a good idea and better if you have someone else doing the work (why pay twice for labor?). If your doing the work yourself its a good project to get more familar with your Vette, and don't mind doing the work again latter.

Have a good tuner around as you will need a good tune to get it to run right and have all the power you paid for... IMO this is true even for using 'stock' cams that are not what was originally in your engine.

If the OP is talking just stock heads, then I would say don't bother until you can get ported heads. A used set of heads is asking for trouble if you don't replaces the springs and seals and match the springs to your cam. And the increase is minimal.

 

Interesting... Stock A4 C5's here were dynoing around 305whp. I'm a bit surprised you're seeing less than 300. M6's were seeing closer to 310-315whp here. Although, that shop is at sea level.

The tuner over at Haddad Motorsports, Tad, is an amazing tuner. He was able to tune out another 20whp on a totally bone stock LS1 Trans Am.

I've never heard of bone stock LS1s making that much on just 243 castings... But yours are ported and you've got headers. An LS6 hot cam, IMHO, is the best way to go.

 

I agree with MattB. My 98 A4 dynoed 294 when it was stock. Most of the stock A4s I know of dyno in the 290s when stock. I have even heard of some dynoing only in the high 280s when bone stock.

 

I can see them dynoing low in Colorado because of altitude, but in Florida?! Really?

Here in Los Angeles, they're dynoing higher than that.

 

290-300 is perfectly normal or average for a stock a4. Rememember a dyno is a tool for measurement of increases for mods.. Stock numbers vary from 285-340 for the LS-1.. All dynos are different!! And there are many variables with the same dynos to consider too.. Its not like getting on a scale and weighing yourself.

 

That's true.

 

There are several issues here.
Stock you have the 241 (or similar) head casting.

LS6 heads are 243 castings with LS6 springs and valves. The valves are hollow and sodium filled to make them very light, and this contributes towards a higher RPM range than the stock valvetrain.

LS2 heads are also 243 castings, just with normal weight valves but are also a direct replacement.

The difference is that the LS2 heads are signifigantly cheaper. New it's on the order of 2k difference for both heads

Changing the heads is a definate improvement, but also adding a cam would help. Here's where you need a little more guidance.

The cam in the LS6 used a smaller base circle so the rockers(?) on the LS6 compensated for this. That means, unless you also use the LS6 cam, you'll need to swap pushrods as well.

Otherwise, there is no differece between the LS6 and LS2 heads. If you can live with the current rev range of your car, then there's no need to pay for the expense of the LS6 heads. If you plan to swap cams for something that is a little more rev happy and have the rev limits changed 500+RPM, than you may be better off with the LS6 heads.

If it were me, when swapping heads, I'd get the base 243 castings and install aftermarket dual springs like Comp 921s and forged pushrods. That way, you're set up for a larger lift cam without worries.

 

Get a mid range cam, clean the heads and put in double springs, add long tube headers and you will be amazed! Porting and polishing can add more hp, but almost doubles the cost of the 243s.

 

The stage 2.5 LS6 heads from TSP aren't that bad priced. I think the patriots are cheaper though. Either way, a good head makes a huge difference, especially when there's a cam, intake and headers involved.