I want more power - Shafiroff 540 or LS?

[Ekliptix]

I bought a used 402 BB with heads/cam a cpl years ago, to replace my 350. The seller claimed the 402 made 430hp, but after a lot of time and money for parts, professional dyno tuning and transmission adjustments, etc the motor is a dog and only made 300whp on a chassis dyno. The motor is just tired. I've yet to take it to the drag strip post tuning, but I'm estimating low 14's at 95mph, as it did mid 14's pre-tuned. I'm not satisfied with the power.




The drivetrain is ready for more power. TCI 700R4, Eaton dif.

I learned my lesson buying a used motor.

I'm leaning towards the most mild 540 Shafiroff makes:
https://www.shafiroff.com/chevy-pump...realstreet.php

540 Pros: compatible with my accessory brackets, transmission, headers, I can make it look OEM-ish with paint, valve covers, etc. No modern computer, gauge retrofit required. My existing Holley Sniper kit is within the 650hp max for the injection capacity. I'd likely change the current 3.73 gear to something more street friendly to take advantage of all the engine torque.

540 Cons: My TCI transmission is rated at 500ft-lbs. The motor above makes 640ft-lbs. I am at 3500ft elevation, so that works out to approx 570ft-lbs at my elevation.

Or, some LS motor. I originally wanted to go turbo LS, but the initial quote (in canada) scared me away. I've since spent more on this BB setup then the LS turbo quote.
LS Pros: Less fuel use, potentially more reliable in the long run.
LS Cons: More money and time for parts: accessories, transmission adapters, gauge stuff, computers, exhaust, etc.


Just writing this all out, it seems sticking with a BB is the less painful route.
Any other opinions?

[PbFut]

Let me qualify that i am a road race guy. Drag race is a very different discipline. So my answer may be a bit off for your use. LS platform is probably the most tunable platform out there. Easy parts and a very simple push rod motor. I used one in a BMW putting over 400 race hours on a build that was run carefully but competitively. The LS holds up and there are so many ways to build the platform, it's hard to beat. That said, in my mind it is difficult to beat the torque of a BB moose configured motor. Given the weight of a truck, me thinks the BB would be more your liking over a LS. I only had 2500 pounds to push around the track. Remember, the HP numbers you see in the adds are gross crank figures and at the wheel on a Dyno is very different. Huffing any motor will give you a lot at the expense of longevity no matter how careful you are so if the Truck is also a street rig, be careful.
If you want to unload the 402, I may be interested depending on timing. Drop a line if you need to move it. Good luck and be sure to keep us posted with your your decision and results.

[Ekliptix]

Thank you for the feedback. I've owned a C6 Z06 with the LS7, and done some road racing. I was even a driver on a team in 24hrs of Lemons! I'm saying this because I appreciate the long-racing abuse LS's can take.

With that said, my c10 is a cruiser that I want to do effortless burnout with, and occasionally run a 12.## quarter mile with. Even with a traditional style BB, I'm hoping it will only need basic regular maintenance for a decade plus. Not sure if this is realistic, but I can call the manf and inquire.

[jimijam00]

Given a 25% loss if you are using an AT, it isn't that far off from the 430 at the fly. It's easy to get 500hp/500tq out of those 402s. Not sure what parts you bought and changed, but they were obviously the wrong ones.

If I were mail ordering a big block, it would be from Mark Jones https://vortecpro454.com/#xl_xr_page_engines

[Ekliptix]

Originally Posted by jimijam00

Given a 25% loss if you are using an AT, it isn't that far off from the 430 at the fly. It's easy to get 500hp/500tq out of those 402s. Not sure what parts you bought and changed, but they were obviously the wrong ones.

If I were mail ordering a big block, it would be from Mark Jones https://vortecpro454.com/#xl_xr_page_engines

The parts I bought and changed from the 350 to support the 402 were not internals-related. They were items to support the engine like the new 7004r, rear end, accessory brackets, sniper EFI, custom tuning. I don't think any of those were 'wrong parts'. According to the tuner, this 402 is just tired. I don't know how many miles were put on it after the previous owner added heads, cam to produce the old 430hp dyno sheet. 120psi was the result of the compression test I did on all cylinders.

In any case, the tuner indicated I'd have to spend a bunch more money to freshen up this 402. Considering how much I've already spent, I'm more inclined to get a new crate motor.

Thanks for the recommendation on VortecPro.

[Accelo]

I am a fan of the LS3's. Not super expensive like the 505hp LS7's. 430HP is the factory rating. Add a mild cam and your in the 550HP range. Easy way to get 400+ hp at the wheels. 100 pounds lighter than an old school SBC. Besides the extra money for the installation their is no downside.

[CantPutTheSmokeBack]

I vote 540. 1. Everyone has an LS these days, but when I tell people my 69 has a big block I get a lot of redneck HELL YEAH BROTHER type of stuff going on which makes me feel good. I actually can't remember the last time I saw someone else with a big block in person. 2. I personally was planning on that exact motor after I get a few more things finished on my truck. So I'm a bit biased. But I have a C30 with more weight to throw around so a bunch more torque is always welcome.

And I say all of this when I still plan on putting another LS in my half ton. Shafiroff has basically just a cammed LS3 package for under 10K and that's likely what I will get for the half ton. Good horsepower numbers but much less torque.

Having done both, they've both got their merits. I have heard a lot of hardcore muscle car guys complain about how the LS sounds, and after having listened to them I have to somewhat agree. It is very V8 throaty, but there is just a bit of higher tones that are sort of european. Not enough to scare me away from one I think they sound just fine, but I can understand the complaint. There is a bit of wiring involved with the LS, and how hard it is depends on which route you go and your experience with electrical. Holley stuff just plugs in, and all you do is tune it yourself or have it tuned. If you decide to build your own harness it's cheaper but you pay that back in your time building it.

Conversely, with the big block you just set timing and jet the carb properly and she's done. Worse mileage, more weight.

If you don't want to buy another transmission, probably look at Shafiroffs LS3. Makes just a hair over the torque your trans is rated at so you'd be much safer than with the big block.
Posted via Mobile Device

[jocko]

Originally Posted by Ekliptix

Just writing this all out, it seems sticking with a BB is the less painful route.

Completely agree - but I think you left out one additional consideration.. The BB will always look better when you raise the hood. If I "had" to choose, I'd opt for the 540 and dress it up to look as absolutely bone stock as possible. There are also a few stepping stones between the tired 402 and a Shafiroff 540 that cost a lot less. You can get a pretty stout 454 or even a 502 before you get near that 540's price tag.

[Ekliptix]

^This, I'd prefer to have a stock-looking engine bay, with 600hp.

Jocko, you're right about other BB options. Blueprint has a 600hp 496 for $3500 less then the Shafiroff option, that could work better with the ratings of my transmission. https://blueprintengines.com/product...etor-bp4967ctc

[Bigdav160]

I built transmissions for over 10 years as my day job. I can't imagine any 700R4 lasting long behind a big block.

I had a '67 step side with a mild 402. I built a 700R4 for it. It worked well but after a year I decided to freshen both up and (I shouldn't have been surprised) the 700R4 was beat.

[mkmc69]

The LS while good in it's own right, is the copy & paste of the hot rod world these days, it seems to me. Making it look like something that belongs in that huge engine bay with the BB is way more cool. Again, just my opinion.

[jimijam00]

What was the results of the warm compression test on this 402?

[Ekliptix]

120psi on all cylinders. I think I performed it with the engine cold, if I recall.
From my internet research, 120psi is quite low.

[jimijam00]

I'm more of a consistency between cylinders kind of guy. Did they do a leak down test?

[Joyridin]

The BBC looks cooler in the engine compartment. Less clutter and it fills the engine bay up nicely. For power and reliability though, the LS is the way to go. As stated, throw a cam in a LS3 and you are good for 570 hp at the crank while still getting 20 mpg. It weighs less, starts all the time, and is just a better all around engine.

Your call though as it depends on what you are looking for. I took out my BBC and put in a L83. The BBC was a huge slug compared to the LT, but I wanted to drive it everywhere with no problems.

[57NAPCO]

Originally Posted by jimijam00

If I were mail ordering a big block, it would be from Mark Jones https://vortecpro454.com/#xl_xr_page_engines

I’ll second Marks builds, I have one of his big blocks he built for me years ago, I run it hard and it’s never given me any issues.

[GASoline71]

that's a crap ton of money just to do "effortless burnouts". Heck, with a truck, a tired 350 can do an effortless burnout.

I'd rebuild that 402 and shoot for a reasonable 450 HP. 450 hp out of a 402 with all that torque is gonna be a blast on the street. It'll sound good and look good too. Plus, that 700R4 you have will handle it.

But that's me...

Gary

[Ekliptix]

A 12.## quarter mile at 3500’ is my goal. Burnouts are assumed . It can do burnouts now.

[LS short box]

Just thought but is the 540 is a tall deck block so your current headers won't work? How about a GM 502 crate.

[GASoline71]

Originally Posted by Ekliptix

A 12.## quarter mile at 3500’ is my goal. Burnouts are assumed . It can do burnouts now.

Sweet! The 355 in my rig put it at 12.97 in the quarter. With that 540 and the right transmission, you'll be able to run deep in to the 11's or into the high 10's if tuned right.

Gary

[toolboxchev]

Originally Posted by mkmc69

The LS while good in it's own right, is the copy & paste of the hot rod world these days, it seems to me. Making it look like something that belongs in that huge engine bay with the BB is way more cool. Again, just my opinion.

I am into technology, yet that is extremely well said.

If I were looking for more......everyday drivability the LS and all the extras maybe worth it. IMHO those come with lots of added time to get everything correct.

Technology works that way.

[jimijam00]

A roller BBC with efi IS reliable.

[SkidmoreGarage]

It sounds like you are a power junkie with experience in wanting to go faster. If that is the case, I'd go LS. If you decide to make more power, the LS will do it more cheaply, easily, and reliably than a BBC. If you want the same torque on the LS down the road, size an appropriate turbo and make more power too. It also helps that the LS family is 40 years newer and has a lot more aftermarket support.

For the trans, I'd say run it and blow it up. When it breaks, in a while, you will have a better idea of what you want. If you are getting serious on drag racing, you will prob want a converter and trans brake. If you just do Sunday cruises and a yearly burnout for the gentlemen in lawn chair crowd, the existing trans will be just fine.

[MikeB]

Originally Posted by Ekliptix

According to the tuner, this 402 is just tired.

I wonder what the tuner means by "tired"? Bad rings, leaky valves, worn-out cylinders? I'd take a look inside before spending big bucks.

120 psi cranking pressure could mean a cam that's too big for the compression ratio. If the rings, cylinders, or valves/guides were worn out, I would not expect to see the same cranking pressure across the board.

[LS short box]

I don't know the weight of your BB but if you decide to go LS all aluminum engine I think you would take at least 250 lbs? off the nose of your truck maybe more?