73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: 81Cheyenne on May 21, 2008, 03:23:14 pm
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I'm going to build a new motor for my 81 C10. I have a brand new set of Vortec heads sitting on the shelf and a complete TBI setup (on a non Vortec intake so I'll have to buy one). I have an extra 350 block and have thought about maybe even bumping it up to a 383. I'm pretty much a neophyte when it comes to fuel injection so this would be a new experience for me but I like the idea of the added response and hopefully fuel economy. I'm looking for some advice here, is TBI worth the expense and work of fitting it up or would I be better off just going with a carbeurated intake?
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Are you building for speed or dependability? Do you have a harness or are you going to have to get one?
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Mostly dependability. Yes, I have a complete (engine compartment) harness.
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If you have most everything, I would do it..
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GM designed TBI to feed a 200hp 350
The higher you go, whether it be in cubic inches or desired HP the more tweaking it's gonna need. (also fuel/air and $$$)
Getting 350 dependable HP out of a Vortec headed 383 with a carb is easy, a 16 year old kid with a Hot Rod or Car Craft subscription could do it.
Getting 350hp out of a 383 TBI is another story. Unless you have deep pockets, a lot of spare time and patience and are into burning your own chips, you may want to think otherwise. (remember the 200hp baseline)
The Vortec heads will require some plumbing to make the EGR functional, as the vortec heads do not have the exhaust crossover.
(http://www.sallee-chevrolet.com/Chevrolet_Intake_Manifolds/images/12496821e.jpg)
running 200hp injectors ain't gonna work
Some have tried the Cop Car injectors (9c1)
Some have tried the bigger 454TBI injectors with the 2" bore Throttle body (vs 1 11/16" for the 5.7)
You are gonna need to see what the TBI is doing should you decide to proceed with you TBI makeover. Guessing won't cut it....
(http://winaldl.joby.se/config.gif)
(http://winaldl.joby.se/sensordata.gif)
(http://winaldl.joby.se/rawdata.gif)
here's some free software
http://winaldl.joby.se/
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Wow. Looks like a pretty steep learning curve. How much difference is there in fuel economy between TBI and carb? Maybe I would be better off going old school. Would it make any difference if I stayed with 350cid?
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Wow. Looks like a pretty steep learning curve. How much difference is there in fuel economy between TBI and carb? Maybe I would be better off going old school. Would it make any difference if I stayed with 350cid?
For drivability TBI wins (cold/hot starts etc...)
For MPG TBI has a slight edge (on a stockish setup)
For low end torque under 2000 rpm TBI wins
For HP above 4500 Carb wins
For anything over 300hp (for the average Joe) Carb wins (there are some that would disagree but they have an intimate working knowledge of TBI, but raise the bar to 350 or 400hp and the story changes)
For reliability I think TBI has the edge
GM built Millions of TBI trucks (and carbs too)
I've owned many of each
TBI is easy to diagnose (with a paper clip) and work on
It's a matter of preference
I like em both
If you were gonna build a (mildly warmed over) TBI motor stick with the 5.7
your chip burner (and your wallet) will thank you for it.
TBI takes a bit more time and effort to tune
just don't go wild ( you are not gonna run 12's with a TBI truck)
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here's some TBI info
http://www.aldlcable.com/
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Is it necessary to run EGR? My state doesn't have emissions testing and I would like to avoid having to plumb for it. I'd like to keep my headers too.
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If you're going to get a chip burned for it, then you can have the EGR taken off the code. Same thing if you megasquirt it, since you're creating your own code.
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I agree, if you are going to go to 383, you are going to have to do some work on the ECM side and some other changes.
If you are going for a mild update on engine though and are going for dependability, TBI is the way to go for cheap.
If you have a 350, you can search around on the net for L05 builds for the caprice 9C1 motors, their came is different than the truck version, but you can get fairly respectible power out of one... and still use TBI,.
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at this point you have 3 options
a) a fire breathing 383 with a carb
b) save a few bucks/ a fire breathing 355 with a carb
c) an approx 250hp torquey TBI 350/355 that gets decent economy with gas at $4 a gallon with no end in sight
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Here's how I'm going to use the truck: First of all, I like to hunt and fish so I would like to be able to pull a fishing boat (with a slide in camper on on rare occasions). I will want to have a little fun with it ;D but it won't be a street rod. I'm thinking on eventually ending up with a 700r4 with a 3.73 posi but it'll probably have a th350 with a 3.08 to start with until I can afford it. It won't be my primary vehicle.
I have a Holley spread bore Qjet replacement and also the TBI. I don't have a Vortec intake for either. The TBI came off of a 90 GMC 2500 (I think).
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I have a Holley spread bore Qjet replacement and also the TBI. I don't have a Vortec intake for either. The TBI came off of a 90 GMC 2500 (I think).
I couldn't get my 4175 to stop leaking :(. But if you want to do spreadbore, the 4175 isn't bad (unless you got the double pumper 4165) but you might be better with a quadrajet. To get decent economy out of the 4175 you kind of have to run a dual stage power valve.
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How well do those adapter plates that convert a 4bbl intake to TBI work? If I used an Edelbrock 2116 and put a plate on it, would it be as good as the GM TBI Vortedc intake? Might give me more options.
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GM used adapter plates on the BBC TBI's
I have one floating around in the garage
It's for a 2" TBI to a spreadbore intake
It has neat vanes to re-direct the air/fuel flow
They were about 1.25" thick and were hollow for hot water to flow in/out
The Edelbrock 2116 would be a good deal
TBI or Carb
Good Idea
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I found one on Ebay (spacer)
The auction includes the TB etc...
I just wanted to show what the GM unit looks like.
(http://www.erbeignition.com/ebay/050201.jpg)
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Cool! I noticed that you can get the aftermarket plates with the TBI holes either toward the front (barrels) in the middle or in the back. Wonder which one works the best? Looks like the GM plate kind of splits the difference. I'll look for that listing on eBay. Thanks.
Update:
Well, I threw a bid at it. Do you think that throttle body off a 454 would be suitable for a 383?
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Here ya go
http://cgi.ebay.com/ebaymotors/Chevy-Big-Block-BBC-454-TBI-Adapter-Plate-EFI_W0QQcmdZViewItemQQ_trkparmsZ72Q3a635Q7c39Q3a1Q7c65Q3a12QQ_trksidZp3286Q2ec0Q2em14QQhashZitem280228700591QQitemZ280228700591
(http://i12.ebayimg.com/04/i/000/f0/3c/68fb_1.JPG)
This one looks a bit cleaner
http://cgi.ebay.com/ebaymotors/Original-454-Carburetor-to-TBI-Adapter_W0QQcmdZViewItemQQ_trkparmsZ72Q3a635Q7c39Q3a1Q7c65Q3a12QQ_trksidZp3286Q2ec0Q2em14QQhashZitem190222976496QQitemZ190222976496
(http://i10.ebayimg.com/02/i/000/f1/53/4cea_1.JPG)
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Update:
Well, I threw a bid at it. Do you think that throttle body off a 454 would be suitable for a 383?
I was gonna do the whole TBI thing a few years ago on an 88 shortbed
I aquired a bunch of TBI stuff and played around with it
I'm sure a 454 throttle body would feed a 383
I have one of those floating around in the garage too
I went as far as boring a stock 350 manifold to accept the 2" TB
Actually I machined a bunch of em and sold em
(I sold the truck for an offer I couldn't refuse, that ended my TBI experiments)
from what I've seen with TBI
Unless you are burning your own chips
or have access to someone that has been down the 383 TBI road before that can help you (with what works and doesn't work) you are pretty much p*ssing in the wind.
I've helped some of the tuners on some of the other chevy truck forums get the 383 TBI's going (mainly parts and 9C1/L19 injectors etc...no tech stuff)
From what I've seen, it's much easier and cost effective to slap a carb on it with a good HEI and call it a day on a conversion like you are doing. The later TBI trucks came with the 4L60E tranny which had to keep the TBI setup.
Most of the guys would jack up the fuel pressure and try to run the SBC injectors at 100% duty cycle till they failed, others have tried the L19 (454) injectors only to run fat/soggy on the bottom end.
I'm sure someone has figuered it out by now
you just gotta find em
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Jasper has a 280hp 383 TBI
Dart heads etc......
Needs a custom chip etc....
Not for use on pollution controled vehicles ect....
http://www.jasperengines.com/pdf/383_TBI_Comparison.pdf
(only 280hp? you can get an easy 325hp out of a carbed, Vortec headed 350 with your eyes closed....)
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Here's an example of a 383 TBI
notice the flat spot at 3500/85mph
Notice the low shift points
while he's got a decent running TBI truck
he'd see nothing but back bumper from a carbed 383
(he nails it at the 44 second mark, takes 24-25 seconds to get to 100)
http://www.youtube.com/watch?v=M6hL8aku4-8
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I was just talking to a friend who likes the Holley Pro-jection setup. He said that he has the ecm under his seat and can tweak the pots for economy or power when the need arises. Do you (or anybody) have any opinions on the Holley TBI?
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Ask your friend a few questions
a) does it have an air temp sensor
b) does it have an airflow sensor
c) does it have a manifold vacuum sensor
d) can it increase idle RPM when the AC compressor kicks on
e) tell me about your O2 sensor
I asked a Holley Rep these questions at a Chevy event a few years ago, I was not impressed with his answers.
Maybe things have changed.
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Ask your friend a few questions
a) does it have an air temp sensor
b) does it have an airflow sensor
c) does it have a manifold vacuum sensor
d) can it increase idle RPM when the AC compressor kicks on
e) tell me about your O2 sensor
I asked a Holley Rep these questions at a Chevy event a few years ago, I was not impressed with his answers.
Maybe things have changed.
Just looking at the manual for the Pro-Ject available on the Holley web site:
a) no air temp sensor (just coolant temp)
b) no air flow sensor
c) no manifold vacuum sensor
d) seems to have a fast idle solenoid for A/C compressor
e) has an O2 sensor but listed as "optional"
Looks like their MPFI setup has all the sensors.
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I looked at converting to EFI a few years ago
First I looked at the Megasquirt
http://www.megasquirt.info/allQs.htm
I was thinking of doing an L98 type conversion for my 82
Cool stuff for a DIY deal
F.A.S.T. has a few choices
http://www.fuelairspark.com/Products/chevy/sb/efi.asp
But I hear they are pricey, but easy to get big HP/TQ
There is just simply not enough time in my life to do the things I "want" to do.
Family, Work and Fishing are at the top of the "need to do" list...
I pull my boat at least 6000 miles a year, spending a couple grand and countless hours wrenching, ebaying and tuning to convert to EFI would have cut into my FWF time....
That's why I went with a Carb.
http://smicarburetor.com/products_/?sfID1=14&sfID2=9&sfID3=32
Took me all of 45 minutes to bolt it on
went fishing the next day
I pull also with a 94 TBI (5.7L-3.73's) Suburban or a 2000 Tahoe Limited (5.7L-3.42's).
The 82 has more grunt with the TH350 and 3.08's and I don't have to worry about jumping in it after a day of fishing/diving/sunscreen/bugs/blood/mud/seaweed etc.....
I get roughly the same MPG towing as the EFI trucks with the SMI Stage II carb (within .5 MPG). Unloaded, the EFI trucks get about 2 MPG better on the road (city driving MPG sucks in all three)
Now that Gas is $4.00+ a gallon, I guess an extra MPG or two, may have helped, but who could have forseen that. My solution is to make more money, I'm not cutting back on my standard of living, the Tuna are running and Lobster season is right around the corner......
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http://www.megasquirt.info/
(http://www.megamanual.com/ms2/MT_front.GIF)
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There is just simply not enough time in my life to do the things I "want" to do.
Family, Work and Fishing are at the top of the "need to do" list...
I pull my boat at least 6000 miles a year, spending a couple grand and countless hours wrenching, ebaying and tuning to convert to EFI would have cut into my FWF time....
That's why I went with a Carb.
Ya know, when you put it like that, it makes for a strong case to slap a 2116 on it, throw on one of my carbs and leave TBI a later day. Maybe I'll throw in a O2 sensor with a gauge just to help with tuning.
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I've had carbs and TBI. 87 355 TBI 4speed 4x4 . 84 355 Holley 750 4speed 4x4 the 84 always got better milage and had way more power
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There is just simply not enough time in my life to do the things I "want" to do.
Family, Work and Fishing are at the top of the "need to do" list...
I pull my boat at least 6000 miles a year, spending a couple grand and countless hours wrenching, ebaying and tuning to convert to EFI would have cut into my FWF time....
That's why I went with a Carb.
Ya know, when you put it like that, it makes for a strong case to slap a 2116 on it, throw on one of my carbs and leave TBI a later day. Maybe I'll throw in a O2 sensor with a gauge just to help with tuning.
If it were me, I'd carb it. You could get a q-jet built for it too so you'd be within so close to fuel injection, it ain't even funny. The question is would you rather wrench or drive? If you were screaming down the track trying to win a race, it would be worth the extra time to dial in fuel injection.
Also for manifolds: http://store.summitracing.com/partdetail.asp?part=SUM%2D226018&autoview=sku
if you running your holley spreadbore or a qjet: http://www.starperf.com/tabloid/page_57.htm professional products
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For dependability, TBI no question. My 87 would start up within a second or two even in 0 degree weather and you could drive away almost immediately. Whereas in my carbed 78, I have to pump the pedal to set the fast idle and wait to warm up a while. Also with the problem of this 10 percent ethanol fuel, the computer will adjust to the change from 10% to 0% ethanol without you having to tune it. My truck runs like crap half the time because I have it tuned for straight gasoline and when I get a tank of E-10 it runs rough, low idle etc.... With TBI it won't matter the computer will sort it out. As soon as I can I want EFI in my truck. My 87 TBI spoiled me and now anything I have has to have EFI. Once you learn to tune EFI It's easier than a carb I think, Though I'm good at both. Good luck!
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looking at a 383 TBI with a 454 TB,, myself ,,plan on it being a torque motor ,,not turn it over 5k