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performance tbi

blackk5350

blackk5350

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am i going to be looking at a reasonable gain with edelbrock intake, tbi space, injector spacer and a chip?

also how do you go about installing #90lb injectors in a 350 as well as how do i go about getting enough fuel preassure, meaning which one shall i get for christmas? thanks guys and

MERRY CHRISTMAS
 
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LOL 90LB injectors are pretty big you sure you want that big? I dont think you can get enough air flow from a 350 throttle body you may have to go with a 454 or something custom. I think a 70-75lb injector would suit you. Injectors are a bigger jump than carb jets.

Theres a lot of improvements to make to a stock one though. break out you dremel tool and remove the lip and smooth every edge you can. Next thin the bar that the butterflys screw to. Modify your pressure regulator to be adjustable or purchace an afterarket one. A injector spacer and either a throttlebody spacer or a aftermarket intake, I dont think the combo of both will gain you anything noticable but you could try it. Next you want a 3 wire O2 sensor and a custom computer tune.

Info here http://www.cfm-tech.com/ or here http://www.strokerengine.com/TBIkit.html or just do a web search theres lots of info out there

OH I almost forgot to put a 454 throttle body on a 350 the intake has to be opened up to fit.
 
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More info for those that don't know.

The stock 4.3, 5.0 and 5.7 throttle body flow 480CFM and have 1 11/16" bores

7.4 throttle body flow 680CFM and have 2" bores.

4.3=45lb per hour injectors
5.0=50lb || || ||
5.7=55lb || || ||
7.4=65lb || || ||
**these numbers are debatable as different years used different injectors but this provides a rough base line to go from.

The mods I suggested in my other post should make it close to 530CFM by best guesstimate, witch should net you some noticeable seat of the pants power.

I don't know if the other thread about the holly 680CFM throttle body is yours or not but that is a 454 unit and the intake needs to be port matched to the throttle body

Also a pair of 90lb injectors........ well thats suited for a 550+HP big block like a 502 or bigger. A built 454 for instance would use 75LB injectors for 450-500HP Please note that this is in a TBI setup.

The biggest aftermarket over the counter throttle body I have seen was a 730CFM with 75lb injectors, made for high performance big blocks.


Please do your research so you dont say something silly like 90lb injectors in a 350 TBI
 
blackk5350 said:
oh sorry. so 75's are enough? i just thought bigger was better. thats what the enzyte commercial says. heres this kit on ebay http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__46mm-bored-TBI-throttle-body-GMC-Chevy-Camaro-Firebird_W0QQitemZ110325191201QQadiZ2865QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item110325191201&_trksid=p4506.c0.m245&_trkparms=72%3A543%7C65%3A12%7C39%3A1%7C240%3A1318

i just need some input from people of how to get power from a stock motor without touching the heads.
Click to expand...

I presume from this post its going to be a stock engine.
If so 60-65lb injectors will be more than enough also these injectors come in a wide range of sizes like 58lb 60lb 64lb ect.

EDIT: when I said 70-75lb injectors I thought you had something more than a stockTBI 350
 
no its just a stock 350 i had no idea what injectors so i just said 90 because they sounded good. sorry for me being an idiot
 
Injectors alone aren't going to help anything.

You need a chip burned and something to enhance flow elsewhere, such as heads, intake, exhaust, etc.

Assuming from your first post by "chip" you mean hypertech or something along those lines, stay the heck away from anything that's off the shelf and supposedly a performance booster. They are worse than worthless.

Even with an intake I think you will be restricted by the heads. Without pulling and porting, you'd be mis-matching parts.

Some of our TBI gurus will chime in I'm sure...about the best you can get bolt on is the "salad bowl" air inlet piece, from what I have seen the TBI folks talk about.
 
dyeager535 said:
Injectors alone aren't going to help anything.

You need a chip burned and something to enhance flow elsewhere, such as heads, intake, exhaust, etc.

Assuming from your first post by "chip" you mean hypertech or something along those lines, stay the heck away from anything that's off the shelf and supposedly a performance booster. They are worse than worthless.

Even with an intake I think you will be restricted by the heads. Without pulling and porting, you'd be mis-matching parts.

Some of our TBI gurus will chime in I'm sure...about the best you can get bolt on is the "salad bowl" air inlet piece, from what I have seen the TBI folks talk about.
Click to expand...
i know not to get a off the shelf chip, im getting one from tbichips, i want to wait until i get all this crap on beofre i tell them what all i have on the engine so i can get a chip that matches what i have going on
 
First of all you wont see much performance gain without doing some performance work on your exhaust. That is the first place you need to spend money if you are still stock.
The stock exhaust is very restrictive. Epically the stock Cat if it has never been replaced or removed.
Headers and good flowing exhaust should be your first mod. Spending a bunch of money Improving the air flow on the intake side. Does no good if you cant get the extra air out the exhaust pipe.
On a stock or mild built engine there is no reason to put any bigger injectors than 65 LB hr.
Re the bigger TB. I run a 46 mm with flow matched 55 lb hr injectors on a mild built 350 still running the stock chip. It works good..... But a bigger TB It is a waste of money if you dont have headers ECT..
If you get a bigger TB you will need an adjustable fuel pressure regulator and guage to properly set the pressure.
You dont need a custom chip for minor bolt on mods like you are talking about.
If you get better/ ported heads or a better cam then yes you a chip.
You can fine tune your engine to run fine on the stock chip with an adjustable fuel pressure regulator. Spend your money on a good obd1 scanner or get WINaldl for free. So you can see what is going on and tune your engine.
 
Thunder said:
First of all you wont see much performance gain without doing some performance work on your exhaust. That is the first place you need to spend money if you are still stock.
The stock exhaust is very restrictive. Epically the stock Cat if it has never been replaced or removed.
Headers and good flowing exhaust should be your first mod. Spending a bunch of money Improving the air flow on the intake side. Does no good if you cant get the extra air out the exhaust pipe.
On a stock or mild built engine there is no reason to put any bigger injectors than 65 LB hr.
Re the bigger TB. I run a 46 mm with flow matched 55 lb hr injectors on a mild built 350 still running the stock chip. It works good..... But a bigger TB It is a waste of money if you dont have headers ECT..
If you get a bigger TB you will need an adjustable fuel pressure regulator and guage to properly set the pressure.
You dont need a custom chip for minor bolt on mods like you are talking about.
If you get better/ ported heads or a better cam then yes you a chip.
You can fine tune your engine to run fine on the stock chip with an adjustable fuel pressure regulator. Spend your money on a good obd1 scanner or get WINaldl for free. So you can see what is going on and tune your engine.
Click to expand...

I agree with this for the most part. But the stock tbi is only around 480cfm any stock truck with TBI would benifit from a few at home mods I sugested. Even with stock exhaust.

However with everything else stock the most I would do is remove the lip and smooth the edges, add an adjustable pressure regulator, add a injector spacer and a crossflow style throttlebody spacer. This will get you closer to 510CFM and will give you a small seat of the pants power increse, also these mods will not require a chip tune. Anything after those few mods will require mods to other parts such as exhaust ect.

TBI is claimed to be flexable to 30% without being re-tuned so just a guess at 15% increase or decrease in performance. Witch is , as far as I am concerned , still a relitivly high number. I do know taking TBI off a 305 and using it on a 350 still seams to run ok but adding an adjustable pressure regulator would help it seam like it was original.
 
i do already have exhaust work done. its crappy and i need it redone but its better than stock. i have the stock manifolds no cat into some glass packs and it exits under the truck. my best bet im assuming is to tear off the olf exhaust and have that redone. i do want mufflers but i want it to be LOUD.

also are we sopposed to have an oxygen sensor plugged in somewhere or is that just a emmisions thing? thanks
 
go read brians stuff at www.tbichips.com lots of good info.

and you have no real exaust work done. the biggest restictor is the stock manifolds.

you can skip the injectors and get a 18 psi spring and bigger pump but all that is listed on brians site.

stock cam is little more than a lawn mower size cam. get a stock 94-97 lt1 roller cam and other parts for a good roller cam swap and power bump.

heck i can list all of it. go read first.
 
original balzer said:
More info for those that don't know.

The stock 4.3, 5.0 and 5.7 throttle body flow 480CFM and have 1 11/16" bores

7.4 throttle body flow 680CFM and have 2" bores.

4.3=45lb per hour injectors
5.0=50lb || || ||
5.7=55lb || || ||
7.4=65lb || || ||
**these numbers are debatable as different years used different injectors but this provides a rough base line to go from.

The mods I suggested in my other post should make it close to 530CFM by best guesstimate, witch should net you some noticeable seat of the pants power.

I don't know if the other thread about the holly 680CFM throttle body is yours or not but that is a 454 unit and the intake needs to be port matched to the throttle body

Also a pair of 90lb injectors........ well thats suited for a 550+HP big block like a 502 or bigger. A built 454 for instance would use 75LB injectors for 450-500HP Please note that this is in a TBI setup.

The biggest aftermarket over the counter throttle body I have seen was a 730CFM with 75lb injectors, made for high performance big blocks.


Please do your research so you dont say something silly like 90lb injectors in a 350 TBI
Click to expand...

90lb injectors in a 350 is not silly. Two 90lb injectors at factory pressure are only good for about 300 horse with the right motor. You would need two 150 lb injectors to get 500 horse. These numbers are based on the calculator found here: http://www.megamanual.com/v22manual/minj.htm#size
 
icehouse said:
90lb injectors in a 350 is not silly. Two 90lb injectors at factory pressure are only good for about 300 horse with the right motor. You would need two 150 lb injectors to get 500 horse. These numbers are based on the calculator found here: http://www.megamanual.com/v22manual/minj.htm#size
Click to expand...


I think you need to do some research as well. Mainly this thread should enlighten you some. Putting 90lb injectors in a stock TBI on a stock engine IS silly no matter how you try to tell me differnt. I try to be nice but damn people need to read before you put your foot in your mouth.
 
now i know you can turn the preassure up on our trucks. i read on tbichips.com that you can do it without buying an aftermarket one. i believe i will go in this order,

1. fix exhaust
2. headers
3. injector spacer
4. maybe tb spacer
5.bored out throttlebody
6.intake
7. extra lube case in cab:D
 
original balzer said:
I think you need to do some research as well. Mainly this thread should enlighten you some. Putting 90lb injectors in a stock TBI on a stock engine IS silly no matter how you try to tell me differnt. I try to be nice but damn people need to read before you put your foot in your mouth.
Click to expand...

I didn't say factory gm tbi 350 with factory tune will work with 90 lb injectors. Go back and read what I said. The original poster wanted to make more than just injector changes to his motor. The 90 lb injectors will work great on a motor with the right mods. Bumping the pressure up on the factory injectors is a better starting point. This will effectively increase the flow rating. GM used the 305 injectors on the 94-95 454 tbi motors but increased pressure from about 12 psi to about 30psi to increase the flow rating from 45 lb to 75 lb. So you can change flow significantly by adjusting fuel pressure. I still stand by my statement that the 90 lb injectors are only good for about 300 horse in the right motor at 12 psi fuel pressure. And I know some people that are succesfully running this setup.

As far as megasquirt goes. I have had really good luck with it. My guess is that you or one of your buddies tried it and failed, so now you think it is stupid. Do some research. Lots of people have had great success with it.
 
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