What kind of horsepower can I realistically expect from a N/A build?

[PumpinIron]

So far I've got the following for my LS3:

- GPI Max Performance LS7 heads
- GPI custom grind cam (for the Max Performance heads)
- MSD Atomic intake manifold (ported as well)
- Full ARH catless headers, mid pipe, and exhaust
- Roto-Fab intake
- GPI tune for 92 octane and a tune for 110 octane

I have yet to install these things (they are waiting in my garage until I get around to it), but from everything I read, I should be able to put somewhere between 500-520 at the wheels, which will be awesome.

The next plan after this is to have a LS3 block bored, stroked, and sleeved to 427 with forged internals. Then I can run higher compression, and possibly a different cam.

My question though is how much horsepower can I realistically expect (on pump gas) to see at the wheels with a full N/A build like this?

The goal is to have it be street-able. Not a daily driver by any means whatsoever, but a weekend fun toy that will be driven very "spirited".

I've heard some say 700rwhp, but that seems like quite a stretch. I was thinking more like 620 at the wheels or something, but I'm not sure.

Anyways, just interested to hear what others have to say about what numbers are actually realistic.

[2010reddevil]

I've seen nasty LS7 builds that barely broke 620whp. Realistically and to be somewhat street able, I'd figure on 580ish whp.

[frey.199]

Originally Posted by PumpinIron

So far I've got the following for my LS3:

- GPI Max Performance LS7 heads
- GPI custom grind cam (for the Max Performance heads)
- MSD Atomic intake manifold (ported as well)
- Full ARH catless headers, mid pipe, and exhaust
- Roto-Fab intake
- GPI tune for 92 octane and a tune for 110 octane

I have yet to install these things (they are waiting in my garage until I get around to it), but from everything I read, I should be able to put somewhere between 500-520 at the wheels, which will be awesome.

The next plan after this is to have a LS3 block bored, stroked, and sleeved to 427 with forged internals. Then I can run higher compression, and possibly a different cam.

My question though is how much horsepower can I realistically expect (on pump gas) to see at the wheels with a full N/A build like this?

The goal is to have it be street-able. Not a daily driver by any means whatsoever, but a weekend fun toy that will be driven very "spirited".

I've heard some say 700rwhp, but that seems like quite a stretch. I was thinking more like 620 at the wheels or something, but I'm not sure.

Anyways, just interested to hear what others have to say about what numbers are actually realistic.

Wait so you have all this stuff already, but you're going to change your block and then replace the stuff you have in the garage?

[gm2376]

Originally Posted by frey.199

Wait so you have all this stuff already, but you're going to change your block and then replace the stuff you have in the garage?

Exactly....seems a bit ass backwards. Your set up may get you mid 500's.

[Juiced1]

Really depends on the dyno but 550rwhp is possible with stock cubes. All out 427 builds can usually get close or just over 600rwhp. 700 would be a real stretch and would take something a bit more extreme that most would be willing to run like a solid roller cam and a ton of compression.

[PumpinIron]

Originally Posted by frey.199

Wait so you have all this stuff already, but you're going to change your block and then replace the stuff you have in the garage?

No, I can re-use everything except the cam. At least that's what GPI told me when I spoke with them on the phone.

I'm going to run it like this for a year or so before upgrading the bottom end, that was my plan at least.

[PumpinIron]

Okay, so 600rwhp is possible but anything above that is probably a stretch. That falls in line with what I was thinking as well.

[frey.199]

Originally Posted by PumpinIron

No, I can re-use everything except the cam. At least that's what GPI told me when I spoke with them on the phone.

I'm going to run it like this for a year or so before upgrading the bottom end, that was my plan at least.

I'm no expert, but I'd def get a second opinion just to be safe. Changing the block I feel is a sketchy area. I'm pretty surprised the heads would work. Makes sense the cam wouldn't work, but usually the cam and heads have to agree with one another in order for things to work.

I just know that usually people will want to base every individual mod off their engine block. Meaning adjusting everything to suit that block. I know some people have done this stuff before and ended up restricting hp gains because they weren't compatible with the engine anymore. They may fit and everything may run, but gains may not be as substantial or go down.

Like I said though, I'm no expert and I don't know this to be true for your circumstance, but have seen it happen a lot of times. If it was me I'd make due with what I had and build from that without changing the block or drop in a whole new engine. Like an upgraded Katech or something. New stroker kit, boring, and such will be pretty expensive if done right. Just my opinion though.

Seems like A LOTTTT of money for a little gain. I'd put it toward a new engine.

[zz430camaro]

This has been done, with the proper intake and cam, you can get to around 540-560 rwhp with the LS3 bottom end

[lazerlemonta]

Originally Posted by Juiced1

Really depends on the dyno but 550rwhp is possible with stock cubes. All out 427 builds can usually get close or just over 600rwhp. 700 would be a real stretch and would take something a bit more extreme that most would be willing to run like a solid roller cam and a ton of compression.

Thats awful. If my 427 didnt make 630-640 I would quit lol We have a 388 making 630, a 427 making 640 (daily driven in south florida) my own sbe LS3 making 562 (drives fine and has been on a few 800 mile round trips this year) with off the shelf heads and cam. People just dont do all the details for NA builds anymore. They slap headers a cold air intake and H/C and call it good. Lots of little tricks to free up power left on the table.

[KW Baraka]

Originally Posted by PumpinIron

So far I've got the following for my LS3:

- GPI Max Performance LS7 heads
- GPI custom grind cam (for the Max Performance heads)
- MSD Atomic intake manifold (ported as well)
- Full ARH catless headers, mid pipe, and exhaust
- Roto-Fab intake
- GPI tune for 92 octane and a tune for 110 octane

I have yet to install these things (they are waiting in my garage until I get around to it), but from everything I read, I should be able to put somewhere between 500-520 at the wheels, which will be awesome.......

With a stock LS3 block, at least 520hp to the wheels.

With a stroker and 12:1 compression, 575+hp to the wheels.

I would also add that the stroker will have substantially more peak AND under the curve torque than the stock displacement block.

KW

[PumpinIron]

When it comes time for the bottom end perhaps I may end up having to go with new heads. If that’s the case I suppose I’ll need to re-evaluate and decide if it’s more worth it for an entirely new engine, or if I’d be better of just slapping on a blower.

The fully built N/A route just really appeals to me for some reason.

[KW Baraka]

Originally Posted by PumpinIron

When it comes time for the bottom end perhaps I may end up having to go with new heads. If that’s the case I suppose I’ll need to re-evaluate and decide if it’s more worth it for an entirely new engine, or if I’d be better of just slapping on a blower.

The fully built N/A route just really appeals to me for some reason.

With your heads/intake, I'd opt for a LS7 or 427+ ci LSx block.

But that's just me!

KW

[PumpinIron]

Originally Posted by KW Baraka

With your heads/intake, I'd opt for a LS7 or 427+ ci LSx block.

But that's just me!

KW

That may be the route I go. I am confident GPI will point me in the right direction when it’s time. I doubt they would give me bad advice.