400 HP motor, TBI or newer injection?

[Coburn]

Hey everyone, I'm gunna put a 400 horsepower motor into my '92 Chevy. It's TBI now and I KNOW it'll need mods and a decent tune.

Instead of running a tuned TBI, should I upgrade to OBDII? Money and harness isn't a problem, I just wanna know is it easier to tune or better for performance? Or would the TBI unit with injectors and a tune do just dandy?

I want good fuel economy too. Is there guna be a difference in MPGs with tuned TBI compared to tuned MPFI or SFI?

[1.721afr]

TBI is the simplest form of EFI, I'm using it on an over 400hp engine.

You don't need a OBDII PCM, you will want one of these,

http://www.dynamicefi.com/EBL_Flash.php

[BlacK20]

first off, whats done to engine?

[GreaseDog]

first off, whats done to engine?

right, because an engine that make 400 hp @ 6500 isn't going to do you any good in a truck with highway gears, big tires, and a stock converter.

[Coburn]

The engine? It's a 4 bolt, Vortec heads, cam, roller rockers, etc...

It don't much matter what the specs are or what the truck specs are... I'm just wondering if tuned TBI will work just fine and give me good economy (meaning not too rich mixture) as compared to MPFI or SFI or anything else

[BlacK20]

The engine? It's a 4 bolt, Vortec heads, cam, roller rockers, etc...

It don't much matter what the specs are or what the truck specs are... I'm just wondering if tuned TBI will work just fine and give me good economy (meaning not too rich mixture) as compared to MPFI or SFI or anything else

Actually, specs on cam would be nice to know.

[BlacK20]

right, because an engine that make 400 hp @ 6500 isn't going to do you any good in a truck with highway gears, big tires, and a stock converter.

Going by his sig, truck sounds pretty stock, and is a standard....

[gmc406]

The amount of money spent converting it over to OBII will take a life time to make back in fuel economy savings, if there are any.



PS
I'm trying to understand this. If money isn't a problem and you obviosly aren't worried about how much it'll cost, why are you concerned about economy?

[Coburn]

Yea it's going into the truck that's in my sig.... NV4500 and a 3.42 or 3.73 gear. I forgot which. ANYHOW, I hate paying for gas just like the rest of us... Money or not. Like one of my buddies once said, "There's a million things I'd rather spend my money on than gas".

So a tuned up TBI unit with bigger injectors is where I should go?

[chevyz71man]

Whats the specs on the cam? Once you get into alot of valve overlap it can get harder to tune speed density. But still id rather run a tbi setup over trying to make a marine intaked vortec setup.

I run my 350 injectors at 60psi Which should support around 500 hp. Gas mileage wont really change by going to obdII, better off with a EBL and messing with lean cruise. I could get 16 out of my old 383 setup on the highway, my new setup when all done and tuned I hope to squeeze 18 with around 450 ft lbs to boot and a lift and 36s.. Although my around town is never much above 10.

[oldred95]

I would go with any sort of multi port injection if you can help it. You will be much happier you did in the end. The problem with TBI is getting the drivability right especially with a stick. If you go with anything but the stock manifold to something thats not heated you are going to have a very wide range in manifold temperatures which means the fuel may want to stick to it and starve the engine out and make a lack of power and response at low speeds or may not stick at all and flash right over to vapor and get sucked in and burnt but at the same time cause it to be overly rich when warm. There are a whole slew of tables to help combat the fuel dynamics to make these things drive right and with a stick they are even more of a PITA to get right. Those silly Gen 3 guys absolutely don't get this and think you want the intake at like absolute zero all the time. Thats why if you get one of them to try and mess with TBI they are like ooga booga 6 liter meh meh meh meh meh. Speaking in general here. Some may understand the difference in injection systems but most don't.

IMO you would be better off getting something similar to the Holley projection efi setup complete with injectors and fuel rails and intake and throttle body and then getting your something stupid simple to work with like the megasquirt fuel injection because simpler is just better. The megasquirt was designed by efi guys to make big power in a nice neat easy to work with package.

[gmc406]

Ya, its been 2 days and no one has said anything about a 5.3/6.0 swap. When I opened the thread for the first time, expecting to see that.

[Coburn]

GMC406, I'd like a 6.0, but only if I bought it in an 03 04 04 Silverado ;)

Anyhow, I think I'll go with a multiport system...

As for the cam, I THINK it's quite similar to this one:
http://www.jegs.com/i/Lunati/638/60101LK/10002/-1

But I'm drawing blanks right now...

[Coburn]

GMC406, I'd like a 6.0, but only if I bought it in an 03 04 04 Silverado ;)

Anyhow, I think I'll go with a multiport system...

As for the cam, I THINK it's quite similar to this one:
http://www.jegs.com/i/Lunati/638/60101LK/10002/-1

But I'm drawing blanks right now...

[silverado_lover]

Ya, its been 2 days and no one has said anything about a 5.3/6.0 swap. When I opened the thread for the first time, expecting to see that.

That's what I came in here to say.

OP why would you only put a 6.0 in a NBS?

You say you want fuel economy? You're not going to get that with a 400 HP GenI engine

[Coburn]

My truck is an OBS?

And I want the best economy I can get... As in if I didn't care, I'd throw on a carb and get 8mpg. When I really could get 15 or 16 with EFI.

[silverado_lover]

Yeah you have an OBS why not put a Gen III in it?

[Coburn]

As in a 6.0?

How hard is it to do that?

[silverado_lover]

Not that hard

[Fast305]

You say you want fuel economy? You're not going to get that with a 400 HP GenI engine

I disagree entirely, the engine in my signature gets 19-20 mpg @ 70 mph in a vehicle that is about as aerodynamic as a brick.