Millenium Z06

Noway I'd trust a stock LS7 block with more than a 150 shot, for the work involved vs the cost, I'd use a sleeved block without a 2nd thought.

You will lose power with a forged rotating assembly, I'm giving up about 20hp using a callies forged crank/rods and forged wiseco pistons do to the increased weight so you will lose power. You'll also be down a bit because forged pistons dont grow (nearly as much as stock hypereutectic pistons do) and therefore not seal the cylinder as well as stock but the trade off is the ability to handle more power reliably.

I'm not sure how much of a difference it will make on how quick the engine revs but with the requirements of what you're wanting to do (300 shot) thats not really something you can worry about unless you are willing to spend $$$$'s on light weight steel rods and crank.

I think you'd be better off spending extra money on the valve train and stick with a good forged BE and eat the 20 or so hp.

Millenium Z06

It will rev a little slower, you have more piston, (assuming a 4.185) and more crank weight in a 4.125. I think I'd stay at a 4.155 and 4.0 to keep the piston speed down and let the motor live longer plus the 4.155 gives you a rebuild and more metal between the cylinders.

You should get 5-7K for your LS7 longblock

lamboworld

Need some help calculating compression. My LS7 heads are milled .030 and I am thinking about using a piston that is -3.8cc and I believe that the stock pistons are -5.3cc. What would my approximate compression be with this setup. This car will still be mostly street driven and I want to run it on 93 without any concerns. My cam is 236/250 114

Thanks

Creamo3

This is the slippery slope with going forced induction on an LS7 and I wrestle with this as well. I broke it down to 2 options:

1. For me if I were to keep the LS7 and hope to keep it reliable around 800-1000whp it needs to be sleeved. I spoke to R.E.D and they charge ~$2k for that alone using a DARTON dry liner or ~2.7k for the MID setup. While the stock crank/rods seem up to task it probably a good idea to upgrade as well while everything is out of the car. All hardware should be upgraded as well.

2. Look into an iron block like the Dart SHP and pay the ~120lb weight penalty but reliably run 1000+whp. You can also have the blocks machined to accept 1/2" studs and run 6-bolt setups. Hopefully you can sell the stock LS7 longblock and recoup some of the costs.

In the end you should budget at least 10-12K to build or replace the motor and that's probably at the cheaper end of things.

Millenium Z06

You dont need an iron block at that power level, a sleeved stock block is more than fine. You'll puke out the crank and rods before the block fails

Michael_D

Bookmark the page at this web site.......... Lot's of very handy calculators, including what you are looking for.

http://www.wallaceracing.com/Calculators.htm

lamboworld

I ditched the idea of rebuilding my LS7 and I bought an HPR darton sleeved LS 454 today. I will have a 2011 LS7 short block with less than 9,000 miles for sale in a few months.

Ghost Knight

lamboworld

Yeah, I know. I want to be able to run a big *** shot of juice at 1/2 mile events and the LS7 short block just isn't up for the task. I should also see a nice bump in N/A power as well. The net cost, after selling my short block, should be quite a bit less than rebuilding my LS7.

lamboworld

After talking to a lot of people I have decided to reuse the TI rods and LS7 crank in my build. In addition to reusing the rods and crank, I am buying a new Darton sleeved 5.3 block and sending my Rods to Katech for bushings/honing and replacing LS7 pistons with CP Carrillo 4.130 pistons.

lamboworld

Looks like my Piston/Pin setup will weigh about 67g less per piston than the LS7 stock piston/pin. I am wondering if this roughly 1.2lbs of weight reduction will add any additional whp or is it not enough to even matter.

I should get my sleeved block soon and I am only going to have to wait on the Rods from Katech to get this build started. Should be completed by the end of October. I will get it back on the dyno to see if there is any difference. I am also adding the PowerBond underdrive balancer so that is the only part other than the pistons that should add any whp. I am also dropping some COPO lifters in as well.

Hopefully this will be a very stout motor once I am finished.

Now I have to decide what to do with my LS7 bare block and pistons.

NIGHTSTALKER

Don't take this the wrong way, but I'm just curious as to why you would want to reuse stock components when you are already going this deep into the build? I know the LS7 crank and rods are good, but how good are they really in comparison to a good aftermarket rotating assembly? For the amount of power you want to make, having the piece of mind that you have a strong setup goes a log way. Just my .02

lamboworld

My biggest reason is that I don't want to give up the light-weight rotating assembly or the acceleration that comes with it. I am not building this car as a track car. It will still spend the majority of it's time on the street and see a handful of 1/2 mile, road race and 1/4 mile events every year. I plan to only use Nitrous in 1/2 and 1/4 mile events and I want to be able to turn up the juice without worrying about cracking a sleeve or breaking a piston. I also want to be able to drive this car hard N/A at 600whp without having much worry either. I anticipate that I will drive it at a 850whp to 900whp on Nitrous less than 10 miles a year. It took me almost an entire year to use my 65lb mother bottle. I also plan to keep this car for at least 5 more years and mostly longer.

My hope is that the Rods will give me no issue at these hp levels if they are rebushed with the use of some upgraded forged pistons.

I can tell you that I could have bought a completely forged shortblock cheaper than what I am doing. However, I can also tell you that I have had many people reach out to me letting me know that they regretted going away from the TI rods.

I will most likely sell my LS7 Bare block and LS7 pistons because there is always someone looking for low mile block that has good sleeves in it.

NIGHTSTALKER

Good luck with it.

Michael_D

Where are you getting the block from?

You might want to reach out to gnx7. I've bought stuff from him before, good guy. He might have another set of rods, already worked by Katech. No idea how he gets them...... https://www.corvetteforum.com/forums...-rebushed.html

lamboworld

Block is from Texas Speed. They are using a new 5.3 LS block and resleeving with Darton Sleeves for 2k.

Good to know about the rods. I assume that my Rods are good other than sending them to Katech to have them reworked.

Millenium Z06

I thought you bought an HPR 454?

Millenium Z06

Yes, you will benefit from the lighter crank and rods, probably ~20whp.
I dont know about the durability of the stock crank and rods at the spray levels you're talking about though

lamboworld

Based on all of the information I could come across, it appears that these Rods are pretty good with the weak spots being the bolts and bushing. I plan on addressing both and switching out the pistons with a forged piston that will have the tops and skirts coated. They should be able to take the abuse and the rotating assembly will also be about 70 grams lighter per cylinder. I am also increasing the cubes to 430ci. I have seen a few people pushing these rods on Nitrous with forged pistons on the stock block but I haven't seen many builds using these rods on a sleeved block. Doubt that I am the first but I haven't found many.

My car is still mostly street driven, but I will run my fair share of events each year. I won't touch the nitrous during road race events and will only run up to a 250 or 300 shot with C16 in a stand alone and some MS109 in the tank during 1/2 and 1/4 mile races. I think that all of the precautions that I have in place will prevent detonation.

Michael_D

I wouldn't bet the farm on gaining significant amounts of power from a lighter rotating assembly. It will definitely rev quicker, and you'd see a faster acceleration rate on an engine dyno...but peak power? I dunno. Maybe a tad.

The bushing work and rod bolts are improvements for longevity and sustained high rpm use. Not detonation or increased cylinder pressure. I think it was Smokey Yunick who said, "It's the stops that kill, not the starts"....or something to that effect. What he was referring to, was the stress the rod bolts and pin bushing see (and the piston too), when the piston changes direction at TDC.

I know a lot of guys are building stroker LS7's, but I don't like that direction. Great for making power, but I think increasing rod angle over what it is already, is a mistake for an engine that will see extended high rpm use. When the trend was to stroke 400CID SBC's, and building 420's, 434's...etc, I was going the other direction. My favorite build was a 377.

Good luck with your engine. I hope you found a good builder. They are not easy to find.