454’s Dying – LS / turbo Swap It or Stay Old School?

[Jeffp541]

My Z28’s 454 is about toast (2–3 PSI hot idle oil pressure). So its Time to rebuild… or ditch it for an LS.


Plan A: What I was thinking when I traded for the Peanut port 454 was rebuilding to my RIP Grandfathers old School Ls7.
All forged 12.5:1 on E85. Sounded badass, but when discussing my grandma straight up told me my grandpa’s old LS7 454 was nothing but trouble and got 6 MPG on race fuel. Shops want $2–3k in machine work, plus $3k-5k in parts easy.


Plan B: My brother works at a scrap yard. I can get a free LS + 4L80E. LQ4/LQ9 or 5.3 aluminum? No problem. Sometimes a 6.2 shows up. T56 would be sick, but rare as hell. Cam it, turbo it, 600–800 HP with decent MPG. Hard to hate that.


I love rowing gears (current Muncie setup), but hard to beat free power.


What would you do? Let’s see pics of your builds!

My wife also wants me to add AC....anyone got any Vintage Air equipped turbo LS engine bay photos you care to share?

Also - If you have gone from a Built 454 to an LS...do you regret it?

Photo for attention....

 

[Icepick23]

Well, I dumped the original small block in favor of the LS3 and T-56 set up. I just wanted something that is very reliable and good on gas that puts out the HP. Old school engines are just that "OLD" IMHO..... Todays LS based engines are by far superior in most cases. Better tolerances and metallurgy meaning they are built to last if you take care of them. The old school engines just won't hold up to wear because they often lack of Nickel and a few other alloys to make a good block and the rotating assembly, plus the manufacturing/design processes has changed dramatically and so on. I always encourage people to update their train of thought. If your going EFI the cost goes up to convert your old carburetor system to EFI. But it's worth it. And yes Vintage Air is a must!

 

[whitefencefarmer]

You had me at free.

 

[G72Zed]

My Z28’s 454 is about toast (2–3 PSI hot idle oil pressure). So its Time to rebuild… or ditch it for an LS.


Plan A: What I was thinking when I traded for the Peanut port 454 was rebuilding to my RIP Grandfathers old School Ls7.
All forged 12.5:1 on E85. Sounded badass, but when discussing my grandma straight up told me my grandpa’s old LS7 454 was nothing but trouble and got 6 MPG on race fuel. Shops want $2–3k in machine work, plus $3k-5k in parts easy.


Plan B: My brother works at a scrap yard. I can get a free LS + 4L80E. LQ4/LQ9 or 5.3 aluminum? No problem. Sometimes a 6.2 shows up. T56 would be sick, but rare as hell. Cam it, turbo it, 600–800 HP with decent MPG. Hard to hate that.


I love rowing gears (current Muncie setup), but hard to beat free power.


What would you do? Let’s see pics of your builds!

My wife also wants me to add AC....anyone got any Vintage Air equipped turbo LS engine bay photos you care to share?

Also - If you have gone from a Built 454 to an LS...do you regret it?

Photo for attention....

Seeing this scenario before, I would suggest you truly "put pen to paper" on both options you are thinking of and include ALL parts and labour, your time, and ALL the modifications and complete details getting both options running.

Obviously the "free" deal from brother swings the balance over to LS, but the "cam it, turbo it" needs to be properly accounted for.

I have customers who stuck with their big block....ya don't need 12.5 domed pistons in a rectangle port LS7 BBC to make power, built it correctly, and you could nail down mid-upper teens in mpg with a carb.......

 

[G72Zed]

Well, I dumped the original small block in favor of the LS3 and T-56 set up. I just wanted something that is very reliable and good on gas that puts out the HP. Old school engines are just that "OLD" IMHO..... Todays LS based engines are by far superior in most cases. Better tolerances and metallurgy meaning they are built to last if you take care of them. The old school engines just won't hold up to wear because they often lack of Nickel and a few other alloys to make a good block and the rotating assembly, plus the manufacturing/design processes has changed dramatically and so on. I always encourage people to update their train of thought. If your going EFI the cost goes up to convert your old carburetor system to EFI. But it's worth it. And yes Vintage Air is a must!

It looks like you and I have a few things in common, clean blue early second gen and the T-56 to name a few, but I'm in the "other old camp" when it comes to the viewpoint of the power plant.

The LS architecture and head design layout is amazing, without a doubt, it's the easiest way to install performance under the hood. If we had LS3/7 in the wrecking yards back in the day, most of the SBC's innovations and development would have slowed or stalled dramatically, but it hasn't at all, the 23* platform is still going.

It's strange, but there are some pro race classes I work in that have introduced the LS based platform to lower the costs of entry, but they had to work on given them weight breaks to make them competitive with Gen1 SBC, and in the end, they still could/can't take the abuse or last the season in many cases, the new versions are better, but still not robust to take the punishment like the old SBC for the most part.

My engine was born in 1968 as a 327 2 bolt main with 240hp, and 57 years later, with an additional NA 300hp, it's still knocking down 20+ mpg's with a 650/750/850/950 carb(s) and reliable as an anvil, I check the lash once a season, and use the full sweep of my tach.

I have big block customers in drag/street and marine that actually removed the EFI and went back to a carb, their milage actually did not suffer, a few got better, and they made more power.....it just depends how deep you want to go, and as the old saying goes, the devil is in the details.

Perhaps the OP should look at doing a proper build of his Big Block Chevy, and get it professionally dyno tuned, and enjoy it. JMO

That’s what’s so nice about this hobby, so many good choices out there.

 

[76z28]

After having both, I would go LS all day every day. The 496 I had did run good, do not get me wrong, but the LS(with a blower) out runs it. It's smoother and I don't have to do anything but enjoy it and change the oil!

 

[73Z L92]

My .02?
A number of years ago I had LS2 block sleeved and stroked to 427 cubes. Sleeving was done RED Race Engine Development out in CA. I used a Manley rotating assembly 24 tooth reluctor. Stock LS3 heads. Small to medium size cam. 3200 stall Yank converter. 3.73 gears.
I used a built 4L60E.
I put it in a 67 Nova.
On the chassis dyno it did just a touch under 500 rwhp with a mild 91 octane tune. So close to 600 hp at the crank?
Piece of cake to drive on the street. 20 MPG on the highway.
I didn't have AC but I don't think adding it would be a problem at all.
Again just my .02. Pic of the Nova engine compartment.

 

[carhead22000]

your not just gonna drop a ls in that car.i had one in my garage when i was rebuilding our old z28.long story short.i have a bbc in it.i know all about the ls and how easy to make power and yes they are great..but not cheap either to get in and running proper.like said above work it out on paper.i had a ton of sbc and bbc parts in stock.very happy with bbc in both cars.a mild 454 with trick flow heads.and a badass 496.

 

[biker]

A good running 6.0 with a cam, headers, valve springs and an LS2/LS3 intake (depending on heads) with a proper tune will make a great fun daily driver.
Nice factory serpentine accessory drive with a modern ac compressor.
Making those things happen takes time, work and money. More money than people think. Fuel system, harness, tuning.
Your big block may not need much to make it healthy again. Polish crank if it measures ok, new bearings, new cam bearings, the right cam and compression and careful assembly and you can have a fun reliable engine.

Dont make it about money. Doing the LS right will cost a decent buck, but in the end, if it hits the goals you want, it's worth it.

 

[Z28PILOT]

I like what biker said. Your 454 is free too. It’s not cracked or blown we think? You might give it a refresh . Clean up the bores , new rings. New crankshaft bearing etc. when I look at the LS motor , I see an ugly alien laying there , just just a mess of 100 parts, tubes , hoses ,runners , wires . The clean old school engines are a thing of beauty. At a show I just admire the cars , pay no attention to LS motors . So if I was diving it to work , using it everyday, then some sort of new motor will hold up better ,you might think. As biker said , there will be more involved than meets the eye , as you are changing everything. If you drag race every weekend , use the LS. The 454 can give you old school CHEAP thrills , without out all the direct port, super high compression, turbos , electronic crap or Computers. I think you might be amazed how a few days at the beauty shop might wake up your tired old 454. Some of them in 70’s would easy run 300,000 in a Chevy suburban , the blocks are very thick and strong. Tear it down , see if it worth fixing ?