98C5RT

If I simply replaced my LS1 heads with LS6 heads on my '98 LS1 block, would I see any HP increase? I only have 34K miles on the engine so I don't want to do the whole H/C swap yet.

I would like to take advantage of the upgraded springs and head design, as well as the coil pack brackets.

Please provide your opinions and advice based on either experience or technical knowledge.

Thanks!

BAMF AE

Yes you will notice some increase.... depending on what other mods you have, I would say (on the conservative side) approx 30-40 rwhp. I say, if you're gonna do heads, ya may as well put the cam in at the same time..I mean, why stop with just the heads when a cam compliments the setup?

Also, keep in mind, it's not just the heads......it's what the tuner does as well. Several people say it always best to tune during winter. Apparently our cars just loooooove the cold air.

Other gurus will check in with their advanced opinions! This forum is awesome!

Good luck!

kpforce1

Simply put, yes you will see an increase in power but it isn't going to be a whole lot using a stock LS1 cam with them. My thoughts are below:

LS6 Heads:

*Smaller chamber (64cc compaired to LS1's 67) will up compression to ~10.8 or so
*Flow better then the LS1 on intake and exhaust side
*Stock LS6 springs will allow you to squeez more RPM's (without the LS6 cam and PCM red line change won't really matter to you)
*Sodium filled valves (lighter - will rev a little faster and be prevent some valvetrain float)


Like I said though, without adding a cam with the LS6 heads you can't take advantage of the benifits they really offer so your power gain will be small. Just my $.02.

I don't really understand your logic to hold off on the H/C swap because the engine only has 34k on it... why wait?

kpforce1

I don't think he would see more than a 20rwhp increase if he just puts the LS6 heads on.

98C5RT

Well I wanted to do the whole H/C swap but I didn't like the $6,300 price tag with me supplying the heads! I figure that I could do a basic head swap myself, then upgrade with a cam package later once I have more miles on the engine.

I usually get a tune with every change I do, so this wouldn't be any different. As for mods, see signature.

jdmvette

click here:

http://forums.corvetteforum.com/show...ighlight=heads

ArKay99

Here is my take on what you want to do.
1: Yes, you will see more power. How much depends on how you set the new heads up.
2: You are going to have to change the head gaskets because the 98 head gaskets are graphite and will be destroyed when you pull the old heads. You will need to clean the deck very well to a very smooth appearance and also make sure the new heads are the same. Once that is done I would recommend using a set of Cometic .040" to .045" thick gaskets depending on what your piston deck clearance is. Less than .005" use the .040", more than .005" use the .045". This will not only increase your CR but will give you a tighter quench which will help ping. You should be around 10.8:1 with a .035" quench height.
3: Measure your lifter preload before you remove your old heads, and after the new heads are installed, use a pushrod length checker and buy chromemoly pushrods of the correct length. The LS6 heads have longer valves than the LS1 heads and together with a tighter quench height you will have a different pushrod length requirement.
4: You will need 99 or later valve covers. The 98 valve covers are perimiter bolt covers and will not fit on the LS6 heads.
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If all the above is done correctly you should see ~20-25rwhp increase.
FWIW the LS6 heads only have sodium filled exhaust valves. They aren't lighter, the sodium helps dissipate heat at the exhaust valve better.
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Check here for a howto on this subject. LS1HowTo . Not saying you will want to do this yourself, but it will give you the insight on what is involved in it. Also, on what is involved in changing the cam. Much more labor on a Y-Body. As you said, might be something you want to have done later on down the road.

muncie21

Couple of comments....

• Heads alone on an NA car should net you 15-20RWHP on a stock LS1.
• LS6 valves are lighter (intake valves are hollow) which allows an increase in redline RPM on Z06 cars.
  LS6 intake = 73 grams, exhaust = 65 grams
  LS1 intake = 101 grams, exhaust = 94 grams
• LS6 valves are 0.6mm or 0.023622" longer. Using a 1.7:1 ratio rocker that works out to 0.0139"
  or basically an extra 14 thousandths more preload in a non-adjustable system. Works with standard pushrods, no problem.

I'm thinking $6K is a little steep for someone to install heads/cam and you providing the heads. New cams run about 300-500. Install should take around 12 hours. Even at $100/h that only adds up to around $2K if you add in the misc. gaskets and other parts.

ArKay99

I stand corrected on the valve weight. The reason I suggested different length pushrods was if he were to use a thinner than stock head gasket. I've also read that stock preload is ~.125" and the stock lifters bottom ~.143".
I agree heads alone should net 15-20rwhp, but if he bumps the CR and tightens quench it should be good for another 5rwhp. Also, chromemoly pushrods flex less than stock pushrods and will give better valvetrain control which will gain a few more hp.
Sure, one can slap stuff on and get good results, but paying attention to the details is why the best tuners always put out cars with better hp and are more reliable than the others. Just my $.02.
I also agree 6K is steep, but is the tuner going to port the heads?

Casem1

LS6 exhaust ports are a much better design, but you won't see a huge increase with the LS1 cam. A new LS6 cam is only $220, put that in too.

Bottom line: they are better heads.

yellow01

that would equate to stronger than an LS6 without the cam... I think 30-40 is a bit much to expect.

SteveDoten

$6300 should get some AFR or ETP heads installed, I currently charge $3395 for the Texas Speed CNC'd LS6 heads/cam package isntalled

BAMF AE

I totally agree, which is why I mentioned "based on other mods he's done" and to be on the conservative side. But with heads alone and no other mods, I dont forsee a major increase.

pianoprodigy

Don't waste your time doing all the work to swap heads for maybe 20 rwhp.

Mitch.Shea

off topic but what will ls6 heads, lt headers, g5x3 cam, cia, z06 ti, ported tb give me on a 99 frc? i plan todo this and i would like to hit 420+ rwhp will i get this?

MagikDraggin

I kind of did it the other way around on mine. I had the cam installed first, and later on had the LS6 heads installed.

According to the dyno sheets, the addition of the stock LS6 heads gained me 20hp in the lower to middle RPM range, and at the power peak of 6200-6400 rpm, only about 8 hp increase.

If I had it all to do over again, I would have had some "work" done on those heads, to maximize the output. As it is now, I'll live with it.

So yes, you will gain some additional power with just the heads, but don't expect anything in the 30-40 hp range...that's just wishful thinking.

Thickraybans

If you lived closer to CT this is what I would do. It's a very good deal.

SLPRC5

My '97 had a H/C LS6 and the LS6 intake. LS6 oil pump, under size pully and #38 injectors. Short headers, 160 T-stat..hi-flow cats,X-pipe and ZO6Ti cat back. Blackwing filter, P&P throttle body. 3:15 diff. Will see how much HP gain after tune and dyno...but it is very strong and fast now.
Rsty

phils C5 vette

Texas Speed has some great cheaper priced heads.

you should be under $3K for parts and labor for install

you'll need a new clutch or a stall

98C5RT

Thanks for all the good advice, keep it coming!