efi vs. carb }{ for my car

[94m6hardtopz]

so ive got a spare virgin bore lt1 block and some nice core heads to build my stroker lt1 out of....

but ive been thinking lately, even with efi there is no way this thing is going to pass emissions anyway and with my budget im only gonna make like 440rwhp or so.

so im thinking about selling this stuff, buying a decend used 1pc rear main sbc block, the same rotating assembly i am gonna buy, some aftermarket heads, intake, and a solid roller. run a good carburetor and a crank trigger and spin the snot out of it. ill have to change the rest of the fuel system, but that wont cost me that much. my trans and everything will bolt up. ill have to change the hood and modify the cowling. i can make more power this way. anybody else on here done it.

[bobbylee]

IMHO a carb can make a little more power than EFI but you will lose torque. The flat torque curve is what makes the LT1's and EFI so great. Fuel injection vs carbs is nothing new. Way back in the day my pal had a Vette with Rochester injection in his shop. While the FI unit was being rebuilt he put a carb manifold on for the owner to drive around with. There was no comparison. The FI made much more bottom end and the owner hated the carb. Plus, FI will give you much better fuel mileage.

[formula97]

this is true, but the carb would be much cheaper to modify and easier to tune. IMO the sounds of and smell of a carburated car cant be beat.

[94m6hardtopz]

im not looking for low rpm torque or gas mileage.

[formula97]

if gas mileage isnt a worry i would have no second thoughts about going with carburation.

[jaberwaki]

i may be in the minority here, but i have built a few carbed motors, 440 RWHP is about 550 motor power... it will take a much more aggressive setup in a carbed small block motor to get this much power, in truth i dont think you will be saving any money...
not that it cant be done, it most curtainly can , but i dont think it will cost that much less...

and tuning a SBC is only easyer if you dont have and know how to use tuning softwere... it takes us 23 seconds to flash a new tune in my ws6... i got 50 bucks says you cant even change jets that fast on your carb
then of course you get to breakout the trusty timing light lock and unlock your dist.

i used to think the same thing... but now that we have our own tuning soft were and are getting very farmiliar with it, it is prooving much easyer and time effective (especially since dyno time aint cheap)

i see it this way man.... there is a verygood reason that old school hot rodders are converting from SBC's to lt1's and ls1's... because they are better .... going backwards seams silly unless its for a BBC ;D

['68SuperchargedLT1Camaro]

Here comes the pissing contest! ;D

Fuel injection is far superior in every way, but carbs are cheap, and you can make similar "peak" HP numbers with them.

It should cost less to do a first gen carburated small block. You just need to look at what you currently have, how much of a hit you'll take selling it, and how much you need to get the old school small block together. You can probably find a 1 piece rear main seal 350 block for near nothing. I come across them every now and then for free.

Cylinder head selection is the $HIT when it comes to 1st gen SBC's, and they're alot cheaper than LT1 heads.

Parts in general are alot cheaper for the old motors. ProForm has an electric water pump for 1st gens for $150.

I know I'm not telling you anything you don't know, but if you really want bang for the buck, find a 400 block. I personally wouldn't do a 1st gen SBC unless it was atleast 406 cubic inches.

I could go on and on, but I'll let you guys argue this one out. ;D

[94m6hardtopz]

first, let me say this, i will be buying an $800 chuck nytten carb if i do this. i can make 440rwhp iwth a hydro roller NA with a ported lt1 intake and heads on a 383. we've done it before. the problem is the stock ported lt1 intake starts to peter out at about 6500. and i want to make closer to 500rwhp.

i have access to one of the best head porters in the world. so thats done. im not talking about using a 750 holley and a dual plane intake off daddys 71 chevy 1/2 ton pickup. im talking solid roller, goooood heads, single plane intake, goooooood carburetor and 7500rpm.

[LT1TA]

Will this be a 383 or a 355?

[DocSpeed]

admin said:

Fuel injection is far superior in every way, but carbs are cheap, and you can make similar "peak" HP numbers with them.

Cylinder head selection is the $HIT when it comes to 1st gen SBC's, and they're alot cheaper than LT1 heads.

Parts in general are alot cheaper for the old motors. ProForm has an electric water pump for 1st gens for $150.

I know I'm not telling you anything you don't know, but if you really want bang for the buck, find a 400 block. I personally wouldn't do a 1st gen SBC unless it was atleast 406 cubic inches.

Cheaper and a wider selection is what turns my head. Making more or = power for less money is always cool. You can tune easier with a carb as stated above but you will be doing it all the time if you want to keep your engine running optimum in different weathers, temps, altitudes, etc.

[94m6hardtopz]

itll be a 383. i might just buy a used lt1 intake, cut it apart and increase the plenum volume. that would solve that problem. the carb route would be about the same amount as the efi setup because by the time you buy an $800 carb, fuel system, set it up with a crank trigger msd setup, change over to a manual rack....blah blah blah. it all adds up. for an NA 383 LT1 the stock electronics and fuel system are fine. hell, i had stock electronics and fuel systems on my turbo and blower mustangs, i had to use vp c16 fuel. but whatever.

[formula97]

from what i understood 94m6hardtopz was starting with a bare block. you could make a ton more power going carb for the same price if you started with ONLY a bare block. and if i was going carb i would definatly go with a destroked 400. best engine. more displacement and will rev way quiker and much higher than a stroker.

[94m6hardtopz]

a .030 400 with a 350 crank is only 377ci. that and the tradeoff on that deal is is the large main bearings of the 400 block. i just dont want to do that.

[formula97]

i just meant more displacement than an lt1, and revs faster than a stroker, whats the problem with large main bearing

[94m6hardtopz]

the problem is friction and heat caused by extra bearing speed.

[formula97]

bearing speed? please elaborate

[Fire67]

Bearing speed has something to do with the diameter of the journals... A larger crank journal diameter means more distance for the bearing to slide around the circle for the same rpm. In other words: a larger diameter jornal creates higher bearing speeds. The problem with that is extra heat caused by increased friction of the increased surface area and the resulting increase in speed. It boils down to affecting parasitic loss and longevity.
But the larger diameter also means a stronger crank.

I was told that a carbuerated setup can make the same peak power on an otherwise identical motor, but never as much torque. Its not just low rpm torque either, its the entire curve... The better fuel atomization creates a higher, flatter torque curve than a carb can touch. When it comes to fuel economy, save the money making power with a carb, then spend all the dough you saved on gas to feed it. Or spend the extra money for the EFI and get the benifits of torque, driveability, reliability, and fuel economy.

[formula97]

i guess it all boils down to what your building it for. a properly setup carburator with a good ignition could have pretty good gas mileage. if your gonna build a car as a daily driver and take on vacation or something than i would definatly go with FI. as docspeed said, you would have to tune the carb alot to drive in different weather or altitudes, but if i was building a car to race on the weekends and to go cruising with, then it would definatly be carbed. its about being different, and theres a reason top fuel cars use carburators.

[94m6hardtopz]

my car gets 5k miles a year put on it max, and i have a beater to drive. im probably going to just buy a used lt1 intake, take it to wolfe's, cut it apart and add plenum volume to it so the powerband wont drop like a stone after 6500rpm.

[Fire67]

94m6hardtopz said:

my car gets 5k miles a year put on it max, and i have a beater to drive. im probably going to just buy a used lt1 intake, take it to wolfe's, cut it apart and add plenum volume to it so the powerband wont drop like a stone after 6500rpm.

If you do that, I'd be extremely interested in pics of the finished manifold... As well as power results. Good luck and keep us posted

['68SuperchargedLT1Camaro]

94m6hardtopz said:

the problem is friction and heat caused by extra bearing speed.

It's a little late, but I just noticed this.

You wouldn't have increased bearing speed if you were to use a 400 block with a 350 crank. The 350 crank has smaller main journals than a 400 crank, so you would need bearing spacers to allow the use of standard diameter small block Chevy main bearings.

The 400 did have larger diameter main journals, but you won't be using those bearings unless you use a large journal 400 crank. With a 377 (destroked 400), you'd be using a 350 crank with the smaller diameter main journals. You can even get a 400 crank (actually nothing more than a 383 crank) with standard diameter main journals. This would allow you to use 350 style bearings while still taking advantage of the big displacement.