GN1R vs Stage II Heads

[juan89]

Hello,

I would like to ask you guys your opinion . I am assembling a 276
CID stage II oncenter for my 84 Corvette at 3,000 Lbs and 3.08
D44 rear. I have a new set of GN1R and a new unported stage II
heads. I would like to make about 650HP. I would like to use the stage II.
What I was thinking is that the heads are very similar to GM L92
LS heads. I think that with the new technology learned from the LSX
engines ,that a mini ls engine can be built with stage II heads.The heads
seem to be very similar.
For example using beehive springs and ls9 cam timing.

I have intakes and new atr headers for both style heads.

Any ideas welcome.

Regards,
Juan

 

[Turbo1dr]

Both sets of heads will get you the power you're looking for. However, the stage heads will take you a lot further. It's your option.

 

[yullose]

You can make 650hp with the 1987 stock production heads.

 

[bison]

I wouldnt use stage 2 heads unless i was targeting well over 1000hp. Your goals could be hit with a set of production iron heads and a hydraulic cam. We are assuming turbocharged.

 

[bison]

You can make 650hp with the 1987 stock production heads.

Lol. never read your post

 

[GNBRETT]

S2 heads/S2 headers. More $$$$.

Not needed for 650 hp. Not even close.

 

[turbodave231]

You probably already know this, but the S2 heads also require unique rocker arms, valve covers and camshaft. S2 heads are 100% overkill for what you want to accomplish........but they are cool!!

 

[juan89]

I would basically want to know how much difference
there is in the street manners between the two.

I have everything for both. I will be using a FAST controller.
I would like to bring the operating range to about 6500 RPM.
In other words I would like to extend the operating range
to make a little more power on the street with less boost.

Regards,
Juan

 

[bison]

I would basically want to know how much difference
there is in the street manners between the two.

I have everything for both. I will be using a FAST controller.
I would like to bring the operating range to about 6500 RPM.
In other words I would like to extend the operating range
to make a little more power on the street with less boost.

Regards,
Juan

6500 is not enough for stage 2 heads. IMO street manners with a solid cam and large turbo that will allow you to start taking advantage of the flow potential will really limit the street manners. You should be able to make 800hp easily with production style heads like the GN1's and 6500rpm.

 

[yullose]

What has me suspicious is... why he only wants to make 650hp with 1000hp parts.

If it were me, I'd use the Stage2 heads and put a really big turbo on it.

With a car that light and 3.08 gears, you should have a top speed well North of 200mph.

To be practical however, do as others have said. Stay conservative and conventional. 650hp is pretty common from nearly stock engines.

 

[JayC]

The GN1s will be better for a street car

 

[Mac in SD]

The S2's will work great on a street car. If you've already got everything you need...why not?

They have a better combustion chamber, more potential if your goals expand, and they look sooooo much better than any stock-type head.

Go for it. Just remember that with bigger ports and valves, you don't need as much duration on the cam.

 

[bison]

The S2's will work great on a street car. If you've already got everything you need...why not?

They have a better combustion chamber, more potential if your goals expand, and they look sooooo much better than any stock-type head.

Go for it. Just remember that with bigger ports and valves, you don't need as much duration on the cam.

Maybe you should define your street car.IMO they suck for a street car. Car will be an absolute pig below 5500. You need much more duration and cam if you have a higher port volume.

 

[juan89]

Guys, here is deal. What I want to do is build my stage II motor.
The car is a 1984 corvette about 3000 LBS, 3,08 gears,4l80 trans
with 3,800 stall and 3 disk lockup converter.Fast CPU , 96LBS injectors.
PCS trans controller. I have a T76 BB turbo.

The short block is a stage II oncenter with DLS 3.625 wide journal forged crank and rods , aluminim pan with Dutwiller external oil pump.

For the top end I have new unported Stage II heads,new Buick valve covers, new T&D roker arms, new single turbo ATR headers, carb intake converted for EFI.

The other option is new champion GN1R ported heads,new champion valve covers,T&D rocker srms, and Cottons 236-236 duration roller cam.

For the champions I am missing the intake and for the Stage II I am missing
the cam.

My idea of streetable is about 1000 RPM idle , 3800 stall. I just want to drive it once in a while with the ocassional drag strip visit.

I figure that if I can use my Stage II heads then I might be able to use my
Champions on a stock block with eagle crank,K1 rods, and girdle and caps.

The new GM trucks come with L92 heads on a 6.0 block. LS3 heads flow
about 300CFM stock and seem to work fine.The 276 CID V6 motor is 276CID
and is the same displacemt per cylinder like the GM 6.0 ls1.

I know my champions flow about 250CFM and unported Stage II might flow
about the same.

That is why I am having a hard time figuring out which way I want to go.

 

[SHADOWII]

Wow!....

I would opt for the cam and use the heads on a spare "streetable " engine.

 

[S2V6RACER]

Production style heads will work better than S2 heads in your project and on your wallet.

 

[Mac in SD]

Maybe you should define your street car.IMO they suck for a street car. Car will be an absolute pig below 5500. You need much more duration and cam if you have a higher port volume.

...and you base your strong opinion on...? Your S2 street car?

Your experiences with a S2 headed street car like mine? That blows the tires away at will? That idles at 800 RPM and passes smog like a new car with 96 lb/hr injectors? That'll run 160 degrees all day in traffic? Check with the guys that saw my car at Bates Nut Farm every year.

I've got big Chapman-ported heads off an ASA car with 2.125/1.625 valves, and I took the cam down to keep velocity up. I'm running an Art Carr 9-inch around 3300 stall and a T-76 BB.

You don't know what you're talking about. I've heard that 5500 RPM crap for years, and it always comes from somebody who has NO experience with it.

 

[bison]

...and you base your strong opinion on...? Your S2 street car?

Your experiences with a S2 headed street car like mine? That blows the tires away at will? That idles at 800 RPM and passes smog like a new car with 96 lb/hr injectors? That'll run 160 degrees all day in traffic? Check with the guys that saw my car at Bates Nut Farm every year.

I've got big Chapman-ported heads off an ASA car with 2.125/1.625 valves, and I took the cam down to keep velocity up. I'm running an Art Carr 9-inch around 3300 stall and a T-76 BB.

You don't know what you're talking about. I've heard that 5500 RPM crap for years, and it always comes from somebody who has NO experience with it.

Whatever bud. Post some real numbers. Your Chapman race ported stage 2 should run 9's at about 16-17psi. Does it? Took the cam down to keep the velocity up. lol. An antique converter and a tiny turbo. Passing an emissions test doesnt mean anything. May be 9.5-9.6 if you neat the balls off it. A street car must be capable of driving thousands of miles in a short period of time like a month. Hundreds of miles in one trip. Driven to the drag strip and run on the street like it is at the strip. I have no clue what Bates nut farm is either. Id street race you with one of my iron headed stock blocks if you were closer.

 

[DailyDrifter]

Whatever bud. Post some real numbers. Your Chapman race ported stage 2 should run 9's at about 16-17psi. Does it? Took the cam down to keep the velocity up. lol. An antique converter and a tiny turbo. Passing an emissions test doesnt mean anything. May be 9.5-9.6 if you neat the balls off it. A street car must be capable of driving thousands of miles in a short period of time like a month. Hundreds of miles in one trip. Driven to the drag strip and run on the street like it is at the strip. I have no clue what Bates nut farm is either. Id street race you with one of my iron headed stock blocks if you were closer.

Sounds like we got a race, and I'm sure you've been to a nut farm or two Bison

 

[bison]

Sounds like we got a race, and I'm sure you've been to a nut farm or two Bison

Too bad im totally serious. No nut farm. Not even Bates:biggrin: . Maybe we will meet up at an event like BG or something sometime. It will be musical engines though since i only have 2 cars and one will be a stage 2. Not with Chapman race ported heads. It will only be a low 9 sec 150+mph drag radial car though . Ive got a good set of s2 head sat my disposal. Maybe ill rethink and call Chapman for some porting