Narrowing down my new LS engine combo..

[Steve1968LS2]

Been digging around and here's how it looks so far.

LS3 block
Darton MID sleeves
FAST Intake
either Trick Flow 235 heads or the new LS3 style AFR heads
Lunati pro-series crank
Lunati rods
Weisco pistons
Compression around 11.1:1

Bore: 4.200

Now if I go with my current 4" stroke I will have 443 cubic inches.. if I go with the next crank at 4.125 I end up 457 cubes. I'm just not sure if that stroke will interfere with the Canton F-body pan that I run to clear my rack.

The more cubes the merrier, but I trying to decide if I should just play it safer and be happy with the 443.

Thoughts?

Here's the cam I selected back when this was going to be a 427.. I might want to go bigger now.
239/247 624/624 lift on a 114 LSA

Thoughts? Looking for midrange and lowend power.

[parsonsj]

Steve,

Unless you are running a tall deck, I think you'll use a *lot* of oil with that much stroke. And I'm not sure you get that much more power. I'd stay with a 4" stroke, and try to keep the piston rock to a minimum.

But the rest of the stuff looks like high quality stuff, for sure.

jp

[parsonsj]

Is that cam a hydraulic roller? Any thoughts on valve-spring life/durability? What rockers are you gonna use?

jp

[Steve1968LS2]

Steve,

Unless you are running a tall deck, I think you'll use a *lot* of oil with that much stroke. And I'm not sure you get that much more power. I'd stay with a 4" stroke, and try to keep the piston rock to a minimum.

But the rest of the stuff looks like high quality stuff, for sure.

jp

I think the pison-rock issue is negated with the Darton sleeves since they are longer (and stronger) than the factory stuff.

Although I would like to stay with a 4-inch stroke and as much bore size as Wiseco can accomodate.

Also, the darton sleeves are round and STAY round with promotes much better ring sealing and you don't get much loss of cylinder pressure (and hence oil) past the rings.

[Steve1968LS2]

Is that cam a hydraulic roller? Any thoughts on valve-spring life/durability? What rockers are you gonna use?

jp

Yea.. Hydraulic.. rockers will either be the bushed stockers like I run now or some Yellow Terra (or Harland Sharp).. COMP has some new super ultra double throw down magnums coming out soon that look pretty light weight.

[CarlC]

8 psi....;-)

[Steve1968LS2]

8 psi....;-)

Oh, you just stop now!!!

I'm trying to resist the urge to add that weight to my car.. displacement is almost weight neutral..

[93Polo]

Oh, you just stop now!!!

I'm trying to resist the urge to add that weight to my car.. displacement is almost weight neutral..

I agree and if you're adding boost why stop at 8 psi :razz:

I'd go with the 4" stroke as you know it clears, and it shouldn't burn oil. The 443 will make plenty of tq.

[CarlC]

8 psi for a high-compression LS is pushing it for pump gas. 6-7 is nice and safe and works in just about any weather with no problems.

An overdriven TVS2300 on a big-cube LS would be epic. Can you say 750hp+ and a silly flat torque curve, all with an itty-bity cam and pump gas? I knew you could.

[Steve1968LS2]

I agree and if you're adding boost why stop at 8 psi :razz:

I'd go with the 4" stroke as you know it clears, and it shouldn't burn oil. The 443 will make plenty of tq.

Trust me.. if I can get a piston near 4.200 I will be all over the 4" crank :)

[Steve1968LS2]

8 psi for a high-compression LS is pushing it for pump gas. 6-7 is nice and safe and works in just about any weather with no problems.

An overdriven TVS2300 on a big-cube LS would be epic. Can you say 750hp+ and a silly flat torque curve, all with an itty-bity cam and pump gas? I knew you could.

If I was only going for the road track deal I would be all over it.. a 440 on boost would be nuts...

But, I like autocross as well and just can't talk myself into hanging 100+ pounds off the front of my car. Even if it is so damn sexy...

[Steve1968LS2]

looks like the magic bore size is 4.185

With a 4" stroke that's 440 cui

With a 4.125" stroke it's a 454

Thinking of just keeping it simple and going 4" stroke.. that's 38 more cubes than what I have now.

660 hp? just a guess..

[Mr.VENGEANCE]

decided against the ls7?

[ss dave]

How about this? 1000hp on an occassion do ya? lol ERL is putting out a 500cc LS with their heads. If I had to do it again and pick an LS powerplant I would talk with Eric at HKE.
http://www.ls1tech.com/forums/generation-iv-internal-engine/1222608-lsx-434-w-wilson-billet-bank-intake-dp-n2o.html

[Steve1968LS2]

decided against the ls7?

Yea.. I get more bang for the buck with a darton sleeved LS2/LS3

[BA.]

Ok, at the risk of sounding like a MO-RON I do have a question or two. :)

I didn't see anything on the AFR heads at their website but I see the TrickFlow heads are a 13.5 degree valve angle.
The new Mast Motorsports heads for an LS3 are at 12 degrees.....like the LS7.
Have you considered the Mast?

Also, on the Trick Flow heads, the ones I see at their website are using the cathedral ports, instead of the LS3/L92 rectangular style, or even LS7 ports. I *think* that would limit you to the 92mm FAST intake and with all those cubes you're aiming at, I was thinking you'd really want the 102mm intake with its' rectangular ports.

On the HP target, I think you'd be near it with that cam and the 102mm intake stuff. 640 - 660 chp is certainly an achieveable target with the big intake. (I have a similarly sized cam for my LS7)
I honestly think that a cam that size is a step or so above the 'low and mid-range power' goal though. Obviously dependant on what stroke you go with.
I have a spreadsheet of spec's from about 22 LS7 camsthat I can share if you want. It's interesting comparative data.

You may have seen this one but here's a build similar to your specs: http://forums.corvetteforum.com/c5-tech/2466652-603-rwhp-583-rwtq-ls3-427-na.html

Oh, one last thing,...is the 11.1 compression a consolation to the Cali. gas?

[Steve1968LS2]

Ok, at the risk of sounding like a MO-RON I do have a question or two. :)

I didn't see anything on the AFR heads at their website but I see the TrickFlow heads are a 13.5 degree valve angle.
The new Mast Motorsports heads for an LS3 are at 12 degrees.....like the LS7.
Have you considered the Mast?

Also, on the Trick Flow heads, the ones I see at their website are using the cathedral ports, instead of the LS3/L92 rectangular style, or even LS7 ports. I *think* that would limit you to the 92mm FAST intake and with all those cubes you're aiming at, I was thinking you'd really want the 102mm intake with its' rectangular ports.

On the HP target, I think you'd be near it with that cam and the 102mm intake stuff. 640 - 660 chp is certainly an achieveable target with the big intake. (I have a similarly sized cam for my LS7)
I honestly think that a cam that size is a step or so above the 'low and mid-range power' goal though. Obviously dependant on what stroke you go with.
I have a spreadsheet of spec's from about 22 LS7 camsthat I can share if you want. It's interesting comparative data.

You may have seen this one but here's a build similar to your specs: http://forums.corvetteforum.com/c5-tech/2466652-603-rwhp-583-rwtq-ls3-427-na.html

Oh, one last thing,...is the 11.1 compression a consolation to the Cali. gas?

Well, accoding to Al over at TF thier 235 heads out flow LS7 heads.. does suck on the intake thoug since I would rather have the 102mm.. BUT.. I want torque so sometimes a bit more restriction is a good thing.

The cam deal I worked out with COMP.. we felt it would have great streatability and put my power band where I want it. Keep in mind I'm shooting for 650hp/580tq but I think, even with the cathedral port stuff that I'll end up at 660/600.. which is plenty.. in fact I don't want more than that.. lol

and yea, I'll take any info you have :)

Yea, I have to run on 91 octane.. bummer

[BA.]

I wouldn't doubt a guy named Al, he's probably right about the 235's outflowing the LS7. The data I don't have, but would be more curious about, is the BSFC comparison. Just something I've always been curious about with the reduced valve angles.

[alnoe]

Hi Steve

Saw your thread and thought I would chime in. With a cathedral port head, you can make 650+ HP all day long with a very basic setup. Our 440 CID dyno engine made 690 HP with a realistic compression ratio, etc.

On the LS7 vs the TFS heads-I want to be clear about flow. I think it is very important to look at flow at .200, .300, .400, .500 etc, rather than just peak flow. Just like HP-it is the area under the curve which matters. Peak flow does not mean a lot in relation to how efficient a cylinder head is.

The factory LS7 heads flow like a sewer at high valve lift but do so at the expense of a very large valve and very large intake port. GM did this intentionlly for a variety of reasons; pumping losses during light throttle cruise (I.E. fuel economy) being one of them.

So, with the 235 head you can make very good power with a bolt together combo. If I get time tomorrow, I will post some dyno graphs and flow info for the 235 heads.

Don't get me wrong-the LS7 head is an extremely good head for an OEM head. But it is very sensitive to cam timing and in my opinion, you can make more power with a smaller port and valve-even if you kept a rectangle port head .

More on my last comment later.

Al

[2ndgenhunter]

Steve,
Just a lil tidbit of info. Fast makes the 102mm intake for the LS1 cathedral port heads. So you can Have you cake and eat it too! :1st:

Good luck with your new motor.


Hers the linky: http://www.fuelairspark.com/0/FS/Intake/Default.aspx