Need guidance -- EFI seems daunting

[Iceman]

I was originally planning to put my '88 Chevy 350 in my Z with a rochester q-jet spread-bore carb. Then I started thinking about using one of the all-inclusive TBI kits for around $1200. Then I started wondering about getting a stock TBI setup on ebay. Then I started wondering about just finding a donor car with FI and pulling everything on my own (might hit a budget limit)...

 

So I am faced with deciding which way to go, and how much risk there is of me getting in over my head trying to do a FI swap (especially with wiring).

 

Any opinions on wether it's worth the effort for a daily driver? (My goal is around 250-300HP)

 

Any opinions on the TBI kits vs finding a donor or snagging a stock setup off ebay. (I see a lot of the stock setups for only a few hundred $ or less)

 

I'll admit I'm a rookie and haven't done an engine swap before. I understand most of the principles, but even the JTR book seems a little daunting when it comes to the transmission section.

 

What I'm currently working with:

'70 240Z

'83(?) L28 w/ SUs

T5 trans (pretty sure it's a borg-warner)

Budget: $2K to start with

Edited September 18, 2009 by Iceman
Fixed title

[WizardBlack]

I was originally planning to put my '88 Chevy 350 in my Z with a rochester q-jet spread-bore carb. Then I started thinking about using one of the all-inclusive TBI kits for around $1200. Then I started wondering about getting a stock TBI setup on ebay. Then I started wondering about just finding a donor car with FI and pulling everything on my own (might hit a budget limit)...

 

So I am faced with deciding which way to go, and how much risk there is of me getting in over my head trying to do a FI swap (especially with wiring).

 

Any opinions on wether it's worth the effort for a daily driver? (My goal is around 250-300HP)

 

Any opinions on the TBI kits vs finding a donor or snagging a stock setup off ebay. (I see a lot of the stock setups for only a few hundred $ or less)

 

I'll admit I'm a rookie and haven't done an engine swap before. I understand most of the principles, but even the JTR book seems a little daunting when it comes to the transmission section.

 

What I'm currently working with:

'70 240Z

'83(?) L28 w/ SUs

T5 trans (pretty sure it's a borg-warner)

Budget: $2K to start with

 

Just a minor clarification, but most people refer to forced induction as FI and electronic fuel injection as EFI.

For that much money, I'd be selling the motor and buying a modern LS style motor with EFI and everything included (from a junkyard) or just keeping it carbed and saving money for the next big step with the car.

[Iceman]

Thanks. I've been trying to think of how much I want to spend, because if I save some of that then it gives me more money for stuff like wheels and paint later.

 

I live in northern CA, so having to deal with winter starts isnt really a big concern, so EFI;-) may not be that much of a benefit. I guess what I would be looking to get from it would be running cleaner and maybe a little bit better mileage. Since my goal is around 250-300HP from a SBC 350, I think I can get that pretty much no matter what.

 

If I pull from a junkyard, is all of the wiring one big blob, or is the engine management stuff separate? Would I have to use the entire wiring harness in place of what I have?

 

Just a minor clarification, but most people refer to forced induction as FI and electronic fuel injection as EFI.

For that much money, I'd be selling the motor and buying a modern LS style motor with EFI and everything included (from a junkyard) or just keeping it carbed and saving money for the next big step with the car.

[letitsnow]

The engine stuff on a TPI 3rd gen f body is a separate wiring harness, I believe it's the same for a TBI..

[Iceman]

Cool. I think it's third gen that I like the look of, where it looks kinda like a spider sitting on top. Am I correct with the understanding that with EFI engines, changes like new cam are automatically adjusted for by the ECU as long as the injectors can handle the extra demand?

 

 

The engine stuff on a TPI 3rd gen f body is a separate wiring harness, I believe it's the same for a TBI..

[strotter]

JTR has an excellent book on the subject, "V-8 Conversion Manual for Chevrolet TPI & TBI Engine Swap". Answers all your questions (and more), a must-read.

[WizardBlack]

Cool. I think it's third gen that I like the look of, where it looks kinda like a spider sitting on top. Am I correct with the understanding that with EFI engines, changes like new cam are automatically adjusted for by the ECU as long as the injectors can handle the extra demand?

I wouldn't say they are all taken care of. A lot of it depends on the particular EFI. Modern stuff is more flexible. The nice thing about carbs is simplicity and some of the performance and sound you can't get with EFI. EFI is nice if you can't tune carbs and want the last bit of drivability and fuel economy.

Have you considered modifications for fuel economy (and emissions)? Water Hydrolysis works and there are special catalyzer 'filters' you can put on your crankcase vent to make them burn up when they get sucked into the intake (Intercharger). I have seen cars first hand with one or both of these with substantial gains. The advantage of modern EFI working at hitting the appropriate A/F target by itself is also a hindrance if you want to tune to a different target.

[letitsnow]

Cool. I think it's third gen that I like the look of, where it looks kinda like a spider sitting on top. Am I correct with the understanding that with EFI engines, changes like new cam are automatically adjusted for by the ECU as long as the injectors can handle the extra demand?

 

With a 'speed density'(MAP) efi system, that's a big no, with a MAF efi system, it's a kinda sorta.

 

The speed density/MAP systems use manifold pressure/vacuum to guess at the airflow through the engine, so if you increase overall flow, the manifold pressure won't change, and it doesn't realize it and doesn't inject the correct amount of fuel.

 

A MAF(mass air flow) system measures the actual flow through the engine, so it CAN compensate for SMALL changes. If you change to a slightly bigger cam or put headers on or change the intake, it will notice and inject more fuel to compensate for more air, up to a limit. You can't take an ecm originally designed to run a stock 305 and put it on a fire breathing 383, it won't like you. Even if it will compensate for your mods, there is still be power to be had with some good tuning. I believe the 3rd gen MAF can read a maximum of 255 grams/sec, which is roughly 300-350 hp if I remember correctly.

[Iceman]

The carb I have is tuned pretty good, but I suppose I could take it to someone and get it tuned even better. It gets about 13mpg average in my '65 GMC with TH400 and 410 rear-end which I've heard is pretty good, especially since my foot sits on the floor a lot .

The sound is pretty unique, especially when I pop the secondaries open. It's interesting how much difference there is in sound between different carbs. I used to have another 4-barrel that had same size secondaries as primaries and they opened right off idle, but about 1/2 the rate that the primaries did. That made for a very NASCAR type sound around 4K-5K RPMS.

 

Sometimes I wonder if I might get better mileage with this carb over EFI since it pretty much just runs on the primaries when you are cruising.

The A/F ratio has been one of the things that has plagued me. I can't get it to not ping in the high (4500+) RPM range. Anything under 4500 it runs nice and clean and the plugs look perfect though. But... I was just reading somewhere that that might have more to do with the HEI dizzy that I have. Apparently HEIs from the '80s were known to be sporatic at 4500+...?

 

I wouldn't say they are all taken care of. A lot of it depends on the particular EFI. Modern stuff is more flexible. The nice thing about carbs is simplicity and some of the performance and sound you can't get with EFI. EFI is nice if you can't tune carbs and want the last bit of drivability and fuel economy.

Have you considered modifications for fuel economy (and emissions)? Water Hydrolysis works and there are special catalyzer 'filters' you can put on your crankcase vent to make them burn up when they get sucked into the intake (Intercharger). I have seen cars first hand with one or both of these with substantial gains. The advantage of modern EFI working at hitting the appropriate A/F target by itself is also a hindrance if you want to tune to a different target.

[Tony D]

After buying a 1990 7.4L TBI engined dually, I rue the day I didn't get an OBD2 compliant (read newer) GM EFI system.

 

The Newer stuff (say an LT out of a 94 Camaro) is programmable through the OBD Port using a program called "Tunercat". I have toyed with it on my buds conversion, and IMO with the OEM fuel trim component and ability to change just about anything you want...I'd spend the $$$ on a newere drivetrain and use it for the swap.

 

Tommy (my bud) got his driveline complete for $1800. That car went 18 miles from the dealer to a telephone pole! Killer deal, and now resides in his 74 Camaro. The tunercat allows you to alter all those pesky things that might throw a code and get you in Dutch with the CAL SMOG people. (Always important)...

 

As for the HEI----with a later engine like the 94...you go "HEI? We don't need no stinkin' HEI!" LOL There are a lot of sites out there devoted to HEI and it's maladies, no need for me to parrot their research here. My main jist was is I was considering a drivettrain or EFI system to go into a car...I'd use the later stuff simply because it's lightyears ahead of the TBI stuff.

 

Not anything against TBI. I have it on the Dually, it's great. It's relatively versatile as I have seen the same system on VW's and Corvairs...if you have a way to burn the chips. The newer systems don't need a prommer to make mods, and you can essentially work them just like a standalone with a cheap software package and a $40 cable to make the OBD2 interface.

 

Good Luck.

[Iceman]

Tommy (my bud) got his driveline complete for $1800. That car went 18 miles from the dealer to a telephone pole! Killer deal, and now resides in his 74 Camaro.

 

That sounds like how I got the engine that I have. The guy who put it into my GMC got it from a full-size blazer that got stuck on RR tracks while messing around 4-wheeling in Placerville.