think i might put the gt4780 on a small ci bbc instead of my 5.3 what do you guys think

 

For all the advantages of an LS you can make very big power with very stock parts in a BBC and do it on pump gas too. Very tough decision in some ways I would base it on parts in the area and parts you have on hand. The other thing is I think an LS would be less costly if you're going with an EFI setup, if you're doing a carb the BBC could easily have advantage over the LS series. The last thing is that if you want to make ultimate pump gas power BBC is probably going to be easier. When you can build a mid 500 CID engine without much work and use the same headers it just makes life easier.

That being said depending on how far the 5.3L is along, I would advise to stick with your plan. Keeping changing constantly is one of the reasons why I don't have shit done on mine compared to where it should be.

 

I think I would do more homework if I were you. Mostly because a well-informed hot rodder wouldn't buy a turbo, then later, willy nilly decide between two very different motors to install it on. I mean, technically you can, but you can also technically impregnate a hooker with AIDS.

I agree with what Drac0nic says, that you can get big cheap thrills with a stock-ish BBC. On the other hand, why wouldn't you go LS? They weigh a lot less, they take up a lot less space, and since you're not looking to take over the world (thus requiring the inches afforded by the BBC *platform*) I'd definitely gear up for LS.

 

If i go bbc it will be carb and 408 ci because thats what i have, as far as the 5.3 i have a stock longblock and thats about it. I dont know much about the ls series engine and am alot more familiar with the bbc but dont know much about turbos but i think i could go either way with the turbo i have. I know i shouldnt be flip flopping so much but i wanted to go with a bbc from the beginning just ran across a deal on the 5.3

 

You're building your combo (car) around a turbo. This is bad news. If a friend gave you a camshaft, would you make a car around it just because? Although I am no BBC expert, I think a GT4780 is already too small for a 408".

I also don't understand "being familiar" with X kind of motor. They're all chunks of metal which are machined and then bolted together. They don't have feelings. I can maybe see knowing a few cute tips and tricks that you can do in your garage or tell your machinist to do, or what kind of timing curve some heads might like, or maybe you have some torque specs and sequences memorized, but thanks to the internet and an abundance of tech books published by really smart guys, none of these things are really big mysteries.

How far into your BBC are you? All put together? Machined and waiting for parts? Pile of sludge in the garage? If this is gonna be a bitchin' street car which is designed to drive nicely and shut down anything in the next lane, I'd set up for an LS motor if you don't stand to lose the farm selling the BBC stuff.

Or: outside of trying to take down Larry Larsen, I personally wouldn't start any turbo project from scratch with a BBC.

(Not trying to sound like a dick....trying to be helpful.)

 

That turbo is capable of feeding out 110lb/min handily. That's some huge power. I think that the BBC probably is going to be a better match if it's cammed and headed properly. The 5.3L will have to spin like crazy to feed that properly in all probability.

 

Not sure I would use the term handily - I think maybe it would except balls-out cranked and on a smaller motor. I can't find a GT4780 map, but if it's anything like the S480 (which was within 98% of the 4780's HP in the 2JZ shootout from the thread)....it would get toasty on a bigger motor (which jives with what Jose says later ---quoted---).

https://www.theturboforums.com/smf/turbo-tech-questions-only!!!/gt47-80-or-88/

I think a fresh, easy-cammed stock headed 400" BBC should grunt out at least 500 FWHP, right?

Also, FWIW our pal Mike kept making great gains with his hydraulic roller cammed (read: not mega screamer) 331" SBF after he ditched his S480 for a hybrid with an 88mm wheel......

https://www.theturboforums.com/smf/the-builds-board-hall-of-fame-builds/5%27-dp-full-3-5%27-exhaust-stock-hood-full-accessory-3700-capri-9-31-146/

Yes, the 4780 can kick out the jams, but there are better choices for a 400" motor which will probably make 500HP without breaking a sweat.

 

bbc should be more fun on the street as far as spool time may have my 80 upgraded to an 88

 

I think a 4780 is a misprint, or it's going to be a hybrid. Don't forget the last 2 digits in the # are to do with the turbine wheel not the compressor. The last #s are going to be 08 or 18 based on what is on Garrett's web site. The pressure ratio where peak flow is only about 2.25 which is fairly minimal.

 

That would be 4508 or 4708....
But 4780 is the old term.....

480, T80, and 4780 map very similar, with the GT having the most flow. All of them are enough to break a stock LSx except maybe the 4.8. I don't think it would break a 2 blt 408 BBC if kept under 6500.
The GTX4508 is the bad boy....excluding the large frame stuff. The maps are in Garrett's new catalog.

Squirrel.pf has most of them if you want to use a turbo calculator.

The 80mm compressor is a tad small for a 408.
Stock small valve bbc heads will still flow similar to a stock 6.0 head.
They will not flow similar to a ported stock valve 6.0 with porting only, they have to get bigger valves to get 300 cfm.
But they have an inferior combustion chamber and won't make as much power in either case.
Once I started looking at cylinder head numbers, I sold off almost all my BBC stuff and went to LSx.
I don't have the coin for a bbc head that only needs 29 deg of timing....if such a thing exists.
But you should be more concerned with the turbine. It's about an 87/80 mm I think.
It is too small for a 408 if you want to rev or turn it up.
It should work fine on 10-12 psi with a little water injection or an IC though. Which will still be plenty of fun
on the street.

But it would be bad ass on a street going 5.3 with the weakest flowing thick deck aftermarket heads.

As far as being familiar with the BBC, it comes down to knowing what works well in a given combo.
As far as a turbo build goes.
You can bolt together a 408 bbc with mostly stock parts (exc cam and pistons) and it will be simliar to a stock similar build 6.0. I'd have no issue using stock rod bolts/bolts in general on the BBC though..... and just try and find BNIB turbo LS pistons for $450 or so. And the oil pan, acc drive, trans fit etc is a just plain simple and no comparison to doing an LS swap.
But it takes a while to figure all that out about the 6.0 when starting from scratch in the LS world.
Not everyone wants to spend the time in front of the computer to pick up 10-20 years of comparable accumulated knowledge for a new engine platform.

But an LS swap will keep the annoying part of the check book wielding lawn chair crowd away from you....


For spool time, you don't want an 88mm.
But an 88mm will be faster even on street tires since it spools slower.
It's similar to the diff between a 408 and 496.
Run what you have. If you don't like it, most anything else will fit in place of the 4780 in terms of a street build.

If I was going to spend your money, I'd get a 6.0, LS6 cam, PAC 1518 springs, .105 or .118 thick wall pushrods, and run the 4780 with the new hooker cast iron manifolds coming out in a month or two with a 650 dp with mods from the carb section and a victor jr w/ msd ignition box for carbed LSx. -oh and a WB o2 setup.

But it's real easy to spend more on a carb than you would on HPtuners and some 80lb injectors w/stock intake
when looking to max out an 80mm.

 

I can go either way, I have traded my 6.0 for a complete custom hot and cold side for my nova since truck manifolds wont work on my car. I thought about going bbc because he will make the headers bbc or ls wich ever i want and I have the complete 5.3 sitting on the engine stand and I also have a solid roller forged piston 408 with steel crank on engine stand too. I cant afford another turbo right now so i need to use the engine that will work best and make the most power for my turbo. And thanks for all the advice

 

sell the bbc, build the 5.3 into a 408 stroker, and make some real power.

imho of course

 

just got a 05 model 6.0 out of a hummer and a set of diamond boost pistons so im headed in the right direction

 

If i had the choice between bbc or lsx it would be bbc all the way. No replacement for displacement! leave the lsx stuff in the junkyard.

 

Not always.....Less weight is a factor also.

 

did you ever weigh an LSX block???

You will make more power with a bbc, have more displacement, a stronger block, which all out weigh the fact it weighs more than small block engine.

 

Dunno about that. There are a few LS series that are making ignorant power even on stock internals. My 4.3L V6 actually weighs only 10 lbs less than an iron block LS series. They weigh nothing compared to a BBC. Could be critical in weight distribution esp. if they're looking to go quick in a way other than in a straight line.

 

Id say its a horse a piece...Id personally go ls1 if thats what you have already. But if starting from scratch Id definitely go BBC.
not really helpfull but just my 2 cents.

 

Ouch. i would never build a bbc in a turbocharged application over an ls. actually not even na would i build a bbc over an ls.

first, keep your 150lbs weight disadvantage, and its negative effects on acceleration,braking, and handling.
then, keep the size disadvantage - it is far easier to fit a big turbo in an engine bay with a small form factor motor like an ls vs a big old bbc.
also, while you are at it, you can keep the difficulty in working the bbc, have to use gasket maker everywhere, turn the engine over like 30 times to adjust valves,etc
forth, keep that slow thing. cube for cube, the ls would walk all over a bbc. 427 ls vs 427 bbc the ls has it by at least 100hp

ill keep my junkyard ls. thanks

 

did you weigh an LSX block??? very close to bbc weight.
IF weight is a concern to you ,an all aluminum bbc is available.
the 150lb disadvantage is more than offset by more displacement, bigger valves,better cylinderheads, stronger block.
I dont know about turning the engine over 30 times but your going to turn it close to that much with any solid-roller cam.
maybe hydraulic cam is for you.

A 427ci bbc has 4.25" bore . Or i could buy a big M with 4.5" bore put a shorter stoke (why??) in it to have a 427ci displacement .
how much valve could you put in that LS engine vs a bbc 4.25"+ bore??

If you dont mind pushing water with your LS than by all means run it. but clearly BBC is a better choice.
A question i have for you is why is there a trend in 10.5 or outlaw drag radial to go to a bigger block and skip the LS engines????