Junkyard TBI prices

[Gurinski]

Is $120 for a complete junkyard TBI system reasonable? It includes ecm, complete harness with sensors and the throttle body.

[FSJ Guy]

If it included EVERYTHING, yes, that's reasonable, depending on the ECM. What ECM is it? You'll want to get a new O2 sensor (they're cheap enough)

Give us some details and we'll let you know if it's worth it or not.

More than likely, unless it's a Howell system specifically for your 360/401, you'll need to be able to burn chips and read data from the ECM and tune it. Otherwise, it won't run as nicely as it could and you'll likely have trouble passing emissions.

[babywag]

How much have you shopped around?

I paid $106 for a complete system from a '90 5.7 van, but I had to pull everything myself, which took a couple hours.

I'd say it's a great price if everything is pulled and it's complete.
Be sure it's from a 350 and not a 305, or you'll need to spend more $$ for injectors.

[Gurinski]

I either plan to burn my own or find a chip set up for a stock 360. I have to pull it myself and could just mix and match parts if I cant get it from one vehicle.

[FSJ Guy]

So, what vehicle is it from and what motor is it on top of? That will tell us if it's worth it and how easy/hard it will be do adapt to your Jeep engine!

[Gurinski]

Originally Posted by FSJ Guy

So, what vehicle is it from and what motor is it on top of? That will tell us if it's worth it and how easy/hard it will be do adapt to your Jeep engine!

They have full size vans and pickups (305,350) from late 80's to late 90's.

[FSJ Guy]

Gotcha. This is from a U-pull it junkyard.

The 1227747 ECM is very popular. TONS of support online for it.

The 16197427 ECM is my new favorite (since it's what I'm running right now! LOL!). It has faster data logging output (as compared to the '7747) for easier tuning, IMHO, but it is a little more complex and intimidating to the first time user.

The '7747 ECM is usually recommended for first time users. It can be found in many mid 80's to 91 Chevys, including Astro vans. But the vans will have the V6, not the V8, so you'll have to buy new injectors. Look for a V8 instead.

The '7427 ECM can be found in 94/95 Chevy trucks and some S10s. Again, you want the V8 ECM and injectors.

[Tinkerjeep]

FSJGuy -you sound very knowledgable in doing this! what kind of performance/ mileage gains have you experienced?

[FSJ Guy]

Originally Posted by Tinkerjeep

FSJGuy -you sound very knowledgable in doing this! what kind of performance/ mileage gains have you experienced?

Performance: No vapor locking, now. Perfect start ups, hot, cold, restart, doesn't matter. Smooth idle in gear or not.

Mileage: No real notable change.

[Tinkerjeep]

Originally Posted by FSJ Guy

Performance: No vapor locking, now. Perfect start ups, hot, cold, restart, doesn't matter. Smooth idle in gear or not.

Mileage: No real notable change.

performance increase any? like quicker 0-60 or stronger when passing?

[FSJ Guy]

Originally Posted by Tinkerjeep

performance increase any? like quicker 0-60 or stronger when passing?

Not really due to the TBI.

I can now adjust my timing curve electronically, so I might have picked up some performance that way, but you can do that with a mechanical distributor, but it's messier. Hard to get your hands dirty programming on a computer.

[jaber]

Not to mention the ability to go from sea level to 10K ft and not have to adjust a dam thing...

[tgreese]

You should see some power increase with TBI. A throttle body system has a better VE than a carburetor, all other things being equal

[Tinkerjeep]

volumetric efficiency is a product of the cam/valvetrain timing. and heads/intake, exhaust. it has little to do with the carb.

[tgreese]

Originally Posted by Tinkerjeep

volumetric efficiency is a product of the cam/valvetrain timing. and heads/intake, exhaust. it has little to do with the carb.

Larger venturi means less pressure drop across the intake tract. Venturi size is not the only determinant of VE, but it is a bottleneck. A carburetor will not work unless there is a pressure differential across the venturi.

[Tinkerjeep]

Originally Posted by tgreese

Larger venturi means less pressure drop across the intake tract. Venturi size is not the only determinant of VE, but it is a bottleneck. A carburetor will not work unless there is a pressure differential across the venturi.

So if you put a blower under or over the carb how does that affect your idea.

I can theoretically design a cam that gets 100% VE with no other changes but cam timing. You can do the same thing. You Get Desktop Dyno?

[tgreese]

Originally Posted by Tinkerjeep

So if you put a blower under or over the carb how does that affect your idea.

I can theoretically design a cam that gets 100% VE with no other changes but cam timing. You can do the same thing. You Get Desktop Dyno?

Forced induction gives VEs greater than 100%. No conflict. There will still be a pressure drop across the venturi, and that factors in to the VE. Read the Wikipedia page.

More than 100% VE without forced induction is unphysical. Air won't move unless there is a pressure difference, and 100% VE requires atmospheric pressure in the cylinders instantaneously when the valve opens. Not physically possible without forced induction.

[Tinkerjeep]

Originally Posted by tgreese

Forced induction gives VEs greater than 100%. No conflict.

okay. and the carb is basically a gate that lets the air into the engine, then the flow chararcteristics of the intake runners, the heads, the valve opening and closing, the RPM range, the elevation of the engine above sea-level, and to some extent the use of scavenging headers and free-flowing exhaust ALL effect VE.

Originally Posted by tgreese

There will still be a pressure drop across the venturi, and that factors in to the VE. Read the Wikipedia page.

And your point is?

Originally Posted by tgreese

More than 100% VE without forced induction is unphysical.

I'm not going to argue this with you.


I'm saying there is more involved with VE than carb venturi size. or FI. A pressure drop WILL occur, regardless of venturi size. True. but tuning the VE with carb choice is bailing out the sinking ship with a cup.

Originally Posted by tgreese

Air won't move unless there is a pressure difference,

Obviously.

Originally Posted by tgreese

and 100% VE requires atmospheric pressure in the cylinders instantaneously when the valve opens. Not physically possible without forced induction.

105% VE is attainable w/out blowers. It takes alot of tuning. Smokey Yunnick or David Vizard has written about it. I don't have Smokey's book anymore and Vizard's is not in front of me. it is attainable though.

[Tinkerjeep]

Okay, looked up VE in a couple books yesterday, and behold over 100% VE is attainable without any blowers to speak of. racing engines do it all the time. Hm. LOOK IT UP.