Tired of my weak TBI 350

[itsorgazmo]

1991 GMCk2500 4x4pu. Has anyone here swapped over to 4 bbl from tbi? This seems the best way to go for the best and cheapest hp gains. This is what I have in mind to get to 300hp from the stock 200. Vortec heads ($500), intake ($250), 600 cfm 4bbl ($300ish), an rv type cam ($200). Just looking to hear from someone who has done it before I go it alone. I also think that my truck cant get much worse gas mi than it doeas now--11mpg. It is all orig w 98K and runs beautifully. thanks

 

[camiswelding]

11 mpg is on the low side... mine gets 12 loaded and 15 empty driven conservatively.... 89 v3500 350tbi


I love the tbi.... I wouldnt get rid of it for a carb
I am doing a frame off resto on mine right now... we have about the same mileage.... I did a roller cam ( my block was already setup... your might be to... that wakes up the motor nicely) then I did all the police package caprice motor tweaks.... a careful reman of the motor.. balanced and blueprinted... nothing totally exotic... but everything just the best I could find over stock

I bet it will see 100 gross hp over stock... with the same mileage....

sure you want to hotrod it....???

 

[itsorgazmo]

what are the police mods you mention?

 

[dirtwarrior17]

I know i already said this in other posts but tbi will support around 400 hp(2BBL holley 670 cfm) if you have the right setup... it costs more but you won't lose all that power up in the mountains like you would with a carb.


I actually bought an edelbrock 750 performer carb and a carb air gap manifold and was ready to install a manual choke cable but right before i got dirty i changed my mind because of the advantages tbi has over a carb. YOu can squeeze 300 hp out of it with little more than a carb would cost.

Carb 2-300
carb manifold 120
carb pump 75

carb conversion=295-395$

holley tbi 350$ new (supports 275 hp with NO computer tuning and can find then on ebay for 150$)
chip 150.
efi manifold 130

efi upgrade=430-630$

A custom chip will make that price jump but with 300 hp as your goal you could probably get away with the right "over the counter chip" to make 300Hp

I spent 700 already and will be spending another 400 for my prominator and labtop.

accel fuel pump 150
holley projection manifold 180
holley 670cfm 2bbl tbi 350
fuel pressure gauge 30
labtop 100
prominator 275

Comes down to personal preference and budget...

I wouldn't go carb unless i had too. I changed my mind because i didn't do enough research on tbi upgrades and then found out about what im telling you.

 

[79chevyk10]

What? I dream of have'in fuel injection, tbi can run at any angle well over even the holley truck avenger. What's your gearing and tire size? Have you tried the throttle body riser? That really wakes up the low end and may improve your gas milage if your running under geared.

 

[Fierospeeder]

I know i already said this in other posts but tbi will support around 400 hp(2BBL holley 670 cfm) if you have the right setup... it costs more but you won't lose all that power up in the mountains like you would with a carb.


I actually bought an edelbrock 750 performer carb and a carb air gap manifold and was ready to install a manual choke cable but right before i got dirty i changed my mind because of the advantages tbi has over a carb. YOu can squeeze 300 hp out of it with little more than a carb would cost.

Carb 2-300
carb manifold 120
carb pump 75

carb conversion=295-395$

holley tbi 350$ new (supports 275 hp with NO computer tuning and can find then on ebay for 150$)
chip 150.
efi manifold 130

efi upgrade=430-630$

A custom chip will make that price jump but with 300 hp as your goal you could probably get away with the right "over the counter chip" to make 300Hp

I spent 700 already and will be spending another 400 for my prominator and labtop.

accel fuel pump 150
holley projection manifold 180
holley 670cfm 2bbl tbi 350
fuel pressure gauge 30
labtop 100
prominator 275

Comes down to personal preference and budget...

I wouldn't go carb unless i had too. I changed my mind because i didn't do enough research on tbi upgrades and then found out about what im telling you.

you mean more like 1500 going the fuel injection route? your up to 1100 if you get your laptop.




I prefer carb. Carb motorcycles and carb hot rods.

You already have EFI on your vehicle. Either you can do your hard parts swap and leave the EFI on there. Or you can always tie up the sensor wires and put them on the side in the engine bay and put a carb on your motor.

You can do a search for my post on the price difference on tools too

 

[dirtwarrior17]

what do you mean 1500? did i add wrong? I have a setup that will support in the neighborhood of 400 hp for 1100. that is just the efi stuff. the rest will make power whether you have efi or not.

his goal is 300 hp.... he can achieve that for 50 dollars more than a carb setup.


I don't know why you think efi needs all these tools.... winaldl is free and you can get a labtop for under 100 dollars of ebay. that is all you need.

carbs have their place but i prefer not to lose 50 hp everytime i start up higher ground.

 

[Fierospeeder]

they use carbs in nhra


the 1500 is estimated. you were listing all the parts for your future upgrades


I did suggest he keep his EFI. If it is already on the truck, might as well keep it. if he wants to add a carb, all he has to do is disconnect the connections and place them on the side.


you can match HP with carb or fuel injection. You wont lose a huge HP numbers because the person decided to go carb. Theres several articles on the topic with dyno data.

winaldl wont fix everything. It is the same information that the ECM sees. If that was the case. The ECM would tell you exactly what is wrong with the system when the MIL light comes on. But it doesn't, it just provides basic trouble codes.

 

[itsorgazmo]

ok guy, what do you think of this---vortec heads(used for $200), vortec tbi manifold($250ish), TB($200), plus the usual. I didnt know anyone made an intake for the vortec heads. They are easily the best heads GM ever put on a small block and they are so cheap I will definately use them. thanks guys. I also put a Corvette servo on the trans and that was the best mod Ive made thus far.

 

[dirtwarrior17]

All those parts i listed are under the hood of the blazer as im typin...


I was saying i spent 700 already and am gonna spend another 400 for the custom chip and labtop.

origianally posted by dirtwarrior17
I spent 700 already and will be spending another 400 for my prominator and labtop.

your right about nhra but efi is taking over... there are a few that pioneered efi setups and most run carbs because they are cheaper...

the top fuelers run injection because they have rediculous budgets.

Carbs are the way to go for the fact that they are simple and easy to setup.... only i live next to a lot of mountains and don't want to be doggin it when the air thins out with a carb.

your also right about winaldl not fixing everything but it gives you the information you need to know to fix the problem... the rest can be done with handtools and a trip to the auto parts store. Keep in mind that in order to get your carb to run at its best you need a way to tell a/f ratio. winaldl does that and a lot more.


itzorgasmo: vortecs will get your where you want to be. They are by far the most cost effective best value head on the market but the fast burns blow them out of the water... but fast burns will cost you twice as much. I beleive gm built the fastburns off the vortecs tho.

vortecs and manifold will get you a quick 60 hp and the bigger tbi will get you another 20. what are you gonna do for a chip?

yup i like the corvette parts on the 700's... i got the whole package when i bought my truck.

 

[84_Chevy_K10]

Have you tried the throttle body riser? That really wakes up the low end and may improve your gas milage if your running under geared.

Actually, the complete opposite is true. If a TBI spacer does anything, it ruins your low end torque. Typically it would do nothing and just be a waste of money.

No reason at all to attempt to increase plenem volume in a 4wd truck IMO.

 

[mightywhitey_k5]

shure the nhra guys run carbs but they dont run at a 60 deg. angle in any way imaiginable if you are planing on making your blazer a nhra drag car use a carb. If you want to crawl every dam Obsitical in your city and that comes in your path when you venture out side the box then stick to your tbi. its just your personal prefrence.

 

[Fierospeeder]

Big foot does. But he might be flying in the air at a 45degree angle.

 

[Fierospeeder]

your also right about winaldl not fixing everything but it gives you the information you need to know to fix the problem... the rest can be done with handtools and a trip to the auto parts store. Keep in mind that in order to get your carb to run at its best you need a way to tell a/f ratio. winaldl does that and a lot more.

you have a lot to learn about EFI grasshopper.

A lot of these trucks run narrow band oxygen sensors. The accuracy of air/fuel ratio is very slim. I know i have the graph, and there is prob a graph someplace on the internet that shows how accurate a narrow band oxygen sensor is compared to a/f ratios. That is why ricers and people with real performance cars are adding wide band oxygen sensors. Most of them dont need it unless they are running engines with turbos,superchargers and nawz.

You dont "have" to know the a/f ratio of a carb. There are several ways to set the mixture on the carb. Vacuum gauge, propane, tach, etc...
Dirt bike mechanics are great at setting up carbs without having a 4 gas analyzer on the field. They need to do it all the time at the track.

To want performance, you want more fuel. thats a richer mixture. You can only go so rich with an engine. You set it before that point.


Theres an issue with EFI in high altitude conditions. But im not going to get into how EFI software works.

 

[Thunder]

What is the issue with EFI at high altutudes????????
Mine works great going straight up a mountain at 10,000 feet. Bettrer than a carb.

they use carbs in nhra

Not for long. More and more are going FI. If you want to go fast you gotta go FI. last time I looked Top fuel were FId

They Use Carbs in Nascar xtel cup/Bush too but only because they have to. Any crew chief would give his left nutwrench to be able to run FI

Super bikes, Fast boats, jet skis, fast snowmobiles, ECT ECT. Are all fuelinjected.
About the only place carbs are still used is MX because of their simplicity and weight savings.

You can stay in the stone age with your carb and go on and on about how much better they are. Fine by me.

I'll stick with FI. I have 5 FId vehicles. Dont think I would ever own a carbed vehicle again. Just got rid of the last carb in my shop (Holley 750) on E-Bay. Some guy called Caveman bought it

 

[RootBreaker]

what are the police mods you mention?

Id like to know this too..

I have a 1991 caprice police 9c1 motor.. sounds spiffy but isnt... 190hp/350ft lb torque but that is with hydro roller cam, tbi, manifolds, single exh, computer...
I have it set with hydro roller cam, truck avenger on a 87 z-28 dual plane intake, headers, duals, no computer

I want to dyno it to see what the difference is over the stock config then decide if I want to just put a bb454 in or change the roller cam.....

 

[Fierospeeder]

Super bikes, Fast boats, jet skis, fast snowmobiles, ECT ECT. Are all fuelinjected.
About the only place carbs are still used is MX because of their simplicity and weight savings.

my friend has a fast boat. It has a chevy small block with a "carb"


Sportbikes are coming out with "very basic" EFI systems. Some people like them and some people dont. The issue with them is that upgrades require the computer to compensate for it, but it cant. So an aftermarket processor/board needs to be bought.

But look how long its taking motorcycles to change. Chevy trucks started at 87 and sportbikes it's becoming a lot more common now. But maybe they are putting fuel injection on motorcycles for something new to come. Like in this decade, motorcycles will be installed with catalytic converters.

Dirtbikes will be coming out in four stroke engines instead of two. They have already started doing that with garden equipment.


There are still a lot of racers that prefer carb.

 

[slyguy_22]

another option

Here is what my budy did with his.
bought a 406ci small block from a local engine builder for 850.00 your heads and intake and everything will bolt right up to it. it will work fine with all stock 350 parts the heads you have to drill (6) steam vents in each one but other than that it is simple. (approx. 400 hp)

Now mine is gona be a 406ci with new heads, intake, & holley replacement tbi.
now you will spend alot more but mine will put out approx. 450hp and a **** load of tourqe.

 

[tiger9297]

Here is what my budy did with his.
bought a 406ci small block from a local engine builder for 850.00 your heads and intake and everything will bolt right up to it. it will work fine with all stock 350 parts the heads you have to drill (6) steam vents in each one but other than that it is simple. (approx. 400 hp)

Now mine is gona be a 406ci with new heads, intake, & holley replacement tbi.
now you will spend alot more but mine will put out approx. 450hp and a **** load of tourqe.

Slyguy, I am looking at the same Holley 670 CFM tbi for my '90 K5. Which heads and intake are u looking at? If I do this will I need to buy a new chip for my truck or just have my chip reprogrammed? I'm looking to get around 450 HP VERY reliable horsepower. My truck is not a DD but gets driven alot and I travel in it from time to time.

 

[dirtwarrior17]

Hate to be the bubble burster but the holley system won't support over 400 hp. you will have to step it up to a 4bbl or mpfi to get there. With bumped fuel pressure and the holley 670 tbi + prominator you can support roughly 375-400 hp...

my friend has a fast boat. It has a chevy small block with a "carb"


Sportbikes are coming out with "very basic" EFI systems. Some people like them and some people dont. The issue with them is that upgrades require the computer to compensate for it, but it cant. So an aftermarket processor/board needs to be bought.

But look how long its taking motorcycles to change. Chevy trucks started at 87 and sportbikes it's becoming a lot more common now. But maybe they are putting fuel injection on motorcycles for something new to come. Like in this decade, motorcycles will be installed with catalytic converters.

Dirtbikes will be coming out in four stroke engines instead of two. They have already started doing that with garden equipment.


There are still a lot of racers that prefer carb.

I can understand you defending carbs because you run one but what are you trying to prove? YOur buddy runs a carb on his boat... whats your point? EFI is better hands down...more expensive but better.

Dirtbikes have been coming out with 4 strokes for the last 5 years(in motorcross) and they have an unfair advantage from the extra cc's. for example 125's run with 250 4 strokes.... thats double the cc. Then you look at 250 2 strokes vz 450 4 strokes... If it was really fair they would need to apply the same rulz as the 125 class and double the cc's of the 2 stroke. That is the WHOLE reason the 250 two strokes are still kicking the 4 strokes asses and the 125 two strokes are getting their asses kicked(even thought the last championship was won on a 125.... just because stewart was riding it tho.) But that has nothing to do with efi. Dirtbikes already cost 6 grand new... they run carbs for the cost, not because they prefer them.

Carbs have been around for decades and there are a lot of people that know their way around em becuase of that.

A narrowband o2 only means the level of gauging is limited it has nothing to do with accuracy. a wideband might measure 10.0 to 18.0 and a narrow might measure 12-16 but they are both equally accurate when the readings are in the band.

If you ask me, you are the one that has a lot to learn about efi...not trying to start **** just my opinion.