hass121

Hi

I've been on the forum for a while although haven't been very active in posting. Recently, my Z06 engine spun a bearing. To cut a long story short, the engine is out of the car and now i'm faced with some decisions:

1) Forged pistons, rings, forged rods but stock crank

2) Texas Speed (or something similar) stroker kit with forged internals

My question is, will the LS7 block be able to take the power from the stroker kit and will it be reliable with the larger crank?

Other mods on the car are:

1) Mamba Cam from Vette Air (carlos) specs: 112+3 240/249 648/648
2) Stainless steel valves with bronze valve liners in valve guides
3) American Racing Headers (no cats)
4) Intake (beehive)
5) Ported Stock Intake
6) Clutch

This brings another question:

As the engine is out of the car anyway and needs to come apart, should I buy a new cam kit? I know the new cams nowadays are better in terms of drivability. Is there another cam that offers similar performance (630hp / 600ft lbs) - the current cam with the specs above lunges quite a bit between 1400 - 1800rpm but pulls very well.

Can any of the cam guys come in and recommend something? I drive the car hard and it has approx 65,000 miles on it.

Any help is much appreciated!

'06 Quicksilver Z06

Good luck with the replacement engine.

Lynch Z06

In my opinion from what I have seen, the LS7 block is not able to take elevated cylinder pressure. I had two sleeves crack after my heads and cam were done.

I went with a RHS block, with forged pistons, stock rods, and crank. My engine builder LME was confident the rods were going to be more than adequate for my application.

I have about a 1000 miles on the new motor and am very happy so far. My car pulls like it has a procharger on it.

hass121

That's worrying! I haven't had any similar issues and i drive it hard..... I'm trying to keep the costs from spiralling so I'm hoping to keep the standard block but forge the internals... any advice from someone who's running something similar?

hass121

Any more advice?

briancb1

I responded to your other thread and I didn't realize your engine was toast.

I have a sleeved LS2 block that's bored and stroked to a 454. It's awesome, but if I was in your shoes I would get the weisco forged pistons that work for your stock rods and use your stock crank.

Get your block zero decked and shoot for high 11's static compression and call it a day. All the money spent on a stroker crank and different rods will buy you very little for the money invested - stock stuff is strong and the power increase is minimal.

Dirty Howie

Sorry about your motor, any idea why it spun a bearing ??


DH

Michael_D

This engine, is already a "stoker", right from the manufacture. Personally, if I had to swap out the crank, I'd shorten the stroke. I'd use the Ti rods and run a JE custom forged piston with relocated pin height. Recondition the rods and change the bolts. The only way I'd increase stroke, would be with a tall deck block. I would MUCH rather increase bore than stroke. But I never have been a big stroker advocate. When others where building 383's, I was building 377's. Not to say I didn't build stroker engines, but they were purpose built, and generally didn't spin much over 6K.

hass121

Pistons will be forged regardless of whether I stroke it or not. Likewise will use forged rods either way. But the question is whether i should stroke or not....

Has anyone owned / driven a stroked z06?

Michael_D

The Ti rods are forged. Why do you think you need to change to a steel rod?

Take a look at the rod angle and ask yourself if you really want to run a heavier rod.

You seem to be set on a forged piston, but no mention of doing anything with the sleeves?

Need more info to be able to make recommendations.

briancb1

Who makes a sub 4" stroke long nose crank for the LS7 dry sump setup?

briancb1

Did you read my post?

I have a 4.185" bore and 4.125" stroke, all possible because of Darton sleeves and a LS2 block.... Callies dragon slayer crank, Callies ultra H beam rods and Weisco pistons (~12:1 compression).

What do you want to know?

hass121

I will be sticking with the LS7 block but going with the 4.1" stroke (callies) crank
4.127" pistons / 6.125" rods from texas speed.

In terms of sleeves i wont be doing anything as (honestly) i dont want to spend that much money

Sorry if that doesnt answer your question, i am new to all of this and simply relaying what i can from the mechanic

Michael_D

Probably nothing sitting on a shelf from any. Who wants to "de-stroke" an engine?? That's blasphemes!!!

But, just for the general audience, Callies, Crower and Scat will custom grind a forged crank in damn near any stroke you want. It will however, require a….wait for it…. wait for it… A PHONE CALL (GASP). In fact, I just got off the phone with Pete at Crower (their crankshaft guy), and they do not have any long snout LS cranks sitting on the shelf. They will however grind you one, any stroke, and no upcharge. It’s just part of the deal.

Vito.A

Interesting. Was this with OEM pistons?
Was the block bored over size?
Is it possible the engine was run under detonation conditions?

The RHS block is certainly superior, but the cost build cost goes up substantially.
Thanks

briancb1

Sky's the limit with a custom job, I was under the impression you found a shelf forging.

I would run a smaller stroke if I was gonna ditch the hydraulic cam and go full solid roller with a nice shaft rocker setup. Take that bitch up to 8000+, let it eat with a nice sheet metal intake and not worry about insane piston speeds.

But no use even if it could with the FAST that would choke it past 6500. It does on mine at least.

I know we disagreed and got at it in the other thread Mike, but I like your thinking here. Someone needs to do a 8300rpm solid roller LS7 and stand out. Makes me wanna go solid roller.

phipp85

I would love to go the 8000+rpm de-stroked route but it will have to wait until I blow up my current motor haha! I know one person who runs a short stroke LS7 and spins it to 8400rpm, he just doesn't post on here. Big autocross and roadrace guy.

Why is the FAST intake so popular if it chokes around 6500? That's a real question, I'm not trying to stir up an argument. I just ported my stock intake, but that's mainly because I didn't want to spend 1K on a FAST.

briancb1

Because my engines just takes in a bunch of air and it wasnt meant for an all out max effort setup.

The FAST is a perfect compromise between street and race. It's an intake where you can gain power at every RPM basically till redline and have no loss in power anywhere. That's pretty awesome IMO. Anything more trick typically will lose something down low to gain it up top.

I had a ported OE manifold and the FAST gave great gains everywhere. It was worth it.

Michael_D

My apologies. There was about a five year cycle that I was experimenting with stroker engines. I’m pretty used to one-off custom grinds. This whole internet shopping for engine parts things is still new to me. I usually just pick up the phone, get hooked up with someone in the tech department (not sales), and tell them my plans and what I want, and get the part ordered. I have nothing against srokers, as long as they are done smartly. I was one of the first guys in my area to build a Gen I based 434 sbc using a two bolt 400 block (with splayed main caps), back in the early 90’s. PITA is what it was….and after one season, ended up dumping the block off at the landfill. I had more time and money in that damn block than buying a new Rocket block. Learned to just buy tall deck blocks after that one.

I prefer to build engines conservatively. Build them to last. Racers tend to get pissed off when things break, and they can’t run a pass or a few laps on their days off. Hard to win a race when your stuff’s broke. So, I don’t concentrate on peak power levels, but consistency and reliability foremost, and peak power secondary. Alcohol for example, makes great power, but not a bracket racer’s best friend. FI has helped, but it’s still somewhat unreliable. I don’t care much for NO2 either. It’s too complicated, and not all that reliable. I’d rather cheat with boost.

My issue with increasing stroke, using a stock LS7 block, is cylinder wall thrust. I do not like to see the rod angle greater than 18 deg, and preferably, under 16. Not to be confused with rod/stroke ratio. The formula I use is: (stroke / 2) / rod length sin = angle ……. The LS7, for example: (4.0 / 2) / 6.1 sin = 18.82 deg

I can’t help but wonder if this is part of why GM decided to go with Ti rods, to reduce cylinder thrust. If you were to increase stroke to 4.125”, and also rod length to the standard aftermarket length of 6.125: you’d end up with an angle of 19.33. Now add some weight from the steel rod. You’ve just compounded the problem. The pistons better be light, and have some trick friction reducing coatings and you better make sure the bore is spot on. I’d also be taking a real close look at the ring package, and sleeve thickness (sonic check mandatory).

PS: I have no problems with disagreement, and in fact appreciate it. It fosters thought provoking discussions and opportunities to learn.

The black bitch.

Erl redid my block and made it a superdeck block much better sleeves ,there slow but there blocks are beautiful works of art ,I feel comfortable with a big shot of nitrous now .