Destroked LS7?

[Lindsey]

I had an LS much like you have asked about, 410 cubes, 760hp and went beyond 8,000rpm.
It wasn't cheap more than the money you have mentioned above (but things were more at the pointy end then)
It had Ti intake & Inconel exhaust valves, Competion Cams solid roller (290deg @ 0.050" & .750" lift), T&D shaft mounted rockers, triple valve springs, ultra light weight pistons, titanium rods, Cola Crank,Custom intake we used an Iron block for strength, an aluminium one probably would have done well too but the weight penalty isn't that great.

It sounded awesome too

 

[Troy]

And that has earlier 'Cathedral Port' heads too? What car was it in?

 

[Lindsey]

Well spotted, those heads had thousands spent on them too, we sure maxed the air flow potential out.
I had it in a Holden VY ute that I drag raced

 

[Greg]

@Dastardly:
That is impressive, certainly more than I would want to pay for.

Ideally I'd like to stay a step below solid lifters. I wish there was more info out there about the capabilities of the Morel High RPM lifters. It sounds like they are certainly more capable than the OEM LS7 lifters and the Cadillac racing lifters.

@ MeLoN BaLLaR:

Yeah the larger bore RHS blocks were what I was looking at. I was thinking perhaps 4.165" x 3.75" and cap the rev limit between 7000-7500rpm. I was also looking at the All Pro heads with T&D or Jesel shaft rockers and their titanium and inconel valve packages. I'm still not sure about what type of valve springs would be required (beehive or dual) or what the limits of the lifters would be. A custom crank and pistons would probably be required and then I'd try to keep everything else off the shelf. I'd like to just top it off with ITBs and see what it does, I'm not looking for massive horsepower, just something a bit more unique. That's why I'm interested in Roberto's (Stage7) build. Although, he'll probably be making quite a bit more power than I'd be looking for I think.

 

[MeLoN]

@Dastardly:
That is impressive, certainly more than I would want to pay for.

Ideally I'd like to stay a step below solid lifters. I wish there was more info out there about the capabilities of the Morel High RPM lifters. It sounds like they are certainly more capable than the OEM LS7 lifters and the Cadillac racing lifters.

@ MeLoN BaLLaR:

Yeah the larger bore RHS blocks were what I was looking at. I was thinking perhaps 4.165" x 3.75" and cap the rev limit between 7000-7500rpm. I was also looking at the All Pro heads with T&D or Jesel shaft rockers and their titanium and inconel valve packages. I'm still not sure about what type of valve springs would be required (beehive or dual) or what the limits of the lifters would be. A custom crank and pistons would probably be required and then I'd try to keep everything else off the shelf. I'd like to just top it off with ITBs and see what it does, I'm not looking for massive horsepower, just something a bit more unique. That's why I'm interested in Roberto's (Stage7) build. Although, he'll probably be making quite a bit more power than I'd be looking for I think.

I've been playing with a spreadsheet looking at various options for high revving engines. Parts only no labor.

LS7 based brand new: RHS, WCCH LSW's, $2500 forged assembly, Isky EZ Rolls, cam gaskets, fasteners, main girdle, LSXR 120MM, accessory kit, +$23K. no labor. 8k RPM, 750hp

LS7 used ($10K), with LSW heads, Isky's, etc, use stock internals. same/similar performance as above, same price too.

LS7 used. springs, CHE rockers, Isky's, fasteners, etc. $14K. 8k rpm, 700hp. pretty good value. Still, double the price of an LS480

this is where my head hurts, because a home built supercar deserves something better(ALEX, WARNING, STOP READING HERE) ...

LS1 4.8L, used. short stroke/long rod engine. takes boost and revs better than any other LSx. reGap top ring to .025-.030, fasteners, gaskets, GT3582r turbos, wastegates, IC, controllers, BOV, isky's, patriot 2007 heads, CHE rockers, cam. 8k rpm, 800hp on pump, 1000hp on race. under $7K. you could do it for less by simply adding springs and CHE's. or even less by being satisfied with 7K rpm. mild or wild as you want. torque demand is where you want it. for a street car that sees occasional track duty I cant think of a better combo. mild turbo cam with a really wide LSA in a 4.8L idles like a kitten. the negative is its probably +150lbs heavier than an LS480(iron block, turbos, intercooler, water for heat exchanger). but if you run over the crank at some point, buy another $500 4.8L, and do it all over again

 

[Schino]

if your running an aftermarket block you wont need a girdle. i really dont think you need a girdle on any ls block that isnt boosted to the moon. a heads, cam, intake setup on an otherwise stock ls7 should be able to make 670-680 at the crank. the 4.8 motors are the absolute best bang for your buck HP wise. i have one thats supercharged on 13-14lbs of boost is making around 650 at the crank. i only turn mine to 6200 but there is no real reason to go past 7200 especially if your on stock rods. you can buy pretty much new short blocks for $225, yes there is not a zero missing at the end. my heads were never pulled (stock headgaskets and torque to yield bolts) and pistons were never pulled (stock ring gap stock rod bolts) only thing changed internal was a mild blower cam. a single 72mm magnum turbo will make one of these motors produce over 800 at the crank somewhat reliably. if you want to see it in action in a 5000 pound truck ill post videos

 

[MeLoN]

if your running an aftermarket block you wont need a girdle. i really dont think you need a girdle on any ls block that isnt boosted to the moon.

I agree. The DART block, yes, a TON (ok, 21lbs) of extra material vs. stock LS7. I've not heard of crank walk on the DART blocks over 1000hp. The RHS block is +3lbs more than the stock LS7. I havent heard of crank walk here, either, but $400 worth of insurance on a $5K block seems cheap. But technically, you're probably right.

LS1/2...........106
LS7..............107
RHS..............110
Dart Billet......128
6.0L Iron.......216
LSX..............230

the actual block weights above may not be perfectly accurate, but, the differences between them are pretty close, as they were all weighed on the same scale.

the 4.8 motors are the absolute best bang for your buck HP wise. i have one thats supercharged on 13-14lbs of boost is making around 650 at the crank. i only turn mine to 6200 but there is no real reason to go past 7200 especially if your on stock rods. you can buy pretty much new short blocks for $225, yes there is not a zero missing at the end. my heads were never pulled (stock headgaskets and torque to yield bolts) and pistons were never pulled (stock ring gap stock rod bolts) only thing changed internal was a mild blower cam. a single 72mm magnum turbo will make one of these motors produce over 800 at the crank somewhat reliably. if you want to see it in action in a 5000 pound truck ill post videos

A basically stock 4.8L with forced induction looks like unbeatable low-cost HP. One of the few LS crate motors built for general aftermarket consumption that ran 8K rpm, the Katech Sneak Attack, had a sleeved LS2 Block (LS7 bore, 4.125), forged 3.268 crank (4.8L spec) and rods. ~350cu/5.7L. This is the motor I'd like to build, but, you are paying a $15K premium for saving 100lbs. makes MeLoN's head hurt.:juggle: