TBI Mods.

[91s104x4]

You really don't need the AFPR but I would really recommend it to bring out the best with these mods. Since you already have a high flowing exhaust system, the AFPR would really bring your truck to life with the TBI and injector spacers. CFMtech recommends that even stock TBI should be set @ 13psi for max performance and mileage. ITs your call.

[Chevy Dude]

I finally completed all of my TBI mods today and so far I'm happy with the results. I did the mods in stages so I will give you my feedback on the different parts.

The first mod was pretty simple stuff. I removed the air snorkle from inside the inner fenderwell, took off the air intake silencer that sets on the inner fender well and replaced it with a straight tube, replaced the stock air filter for a K&N unit that came with a chrome cover that fit the stock air cleaner assm., and added the Hypertech power charger to the top of the TBI. When I added the power charger I cut the bottom of the air filter box off so that it would get better flow.

These mods did not add that much noticable power but it did make for much smoother acceleration with less throttle movement.

The next mods I did were to the TB itself. I shaved the horns at the top of the TB (like they suggested in "The Ultimate TBI Mods"), I installed the 1/4" fuel pod spacer, I installed a fuel pressure gauge at the rear of the TB, and installed a CFM-Tech TB spacer.

These mods did show some increase in power but nothing that made me yell in excitement. Note my stock fuel pressure was set at 12psi from the factory,
thats not to bad.

The last mod I made was today when I started playing with the fuel pressure.
Like I said the stock setting was at 12psi and I have inched it up all the way to 14psi now, and have seen some performance increase. CFM-Tech reccomends 14 to 14.5psi for all of these improvements so I will keep playing with it to see what I get.

I also undersand that it may take a few days for the computer to adjust to all these mods so I will let you all know how things turn out in a couple weeks.

It may be that I will need to also get a custom tune for this to get all that I want from these mods. My goal was to get the 40hp more that they advertised and maybe pick up a couple more miles to the gallon if I can keep my foot out of it. We'll See. Oh and try and keep it smog legal for California.

ChevyDude

[step-a-side]

Originally Posted by Chevy Dude

, I installed a fuel pressure gauge at the rear of the TB, and installed a CFM-Tech TB spacer.
.

ChevyDude

Hi,

what pressure gauge did you use?
and how did you install it??

thanks Tom

[Chevy Dude]

Originally Posted by step-a-side

Hi,

what pressure gauge did you use?
and how did you install it??

thanks Tom

I used a 15psi gauge and adapter that I got from CFM Tech.
You can check out their stuff at www.cfm-tech.com
Lots of good information and parts on that site.

CD

[step-a-side]

Originally Posted by Chevy Dude

I used a 15psi gauge and adapter that I got from CFM Tech.
You can check out their stuff at www.cfm-tech.com
Lots of good information and parts on that site.

CD

thank's,

I have sent a few emails to them the last month but they did never reply to me.
maybe because i live in Europe??
i need more pressure than 15 psi.
Tom

[mbest]

Hi Tom. I don't know thread spec's for fuel lines, but the CFM adaptor uses 1/8 NPT for the T to the gauge itself. Lots of fuel gauges in Summit/Jegs that go to 100 psi. Maybe use CFM's adaptor and a different gauge. Try to pick a gauge that is close to what you think you need, It'll be more acurate
Matt

[h20son]

I picked up my fender to aircleaner air tube, cost me 7.00 at the stealership, ordered for an '88 fullsize with a 305, my Butt Dyno says it was good for 35 hp

[drew_motohead]

well ill post my tbi mods.
1. free tbi mods:shave the horns,make the fuel pres reg adjustable, shaved the little flap holder thingy

2. took out the thing in the snorkel.

3.flip lid but have since put it back. sounded great but made the filter dirty

4. i made a tbi spacer out of 1 inch MDF and 2 tbi gaskets. works really well for now, definatly helped the power, but after xmas will get a aluminum one.

5. made a injector spacer out of 1/4 inch pastic. not sure how much that itelf helped, but with the bowl and spacer, really upped my flow.

6. made a "power bowl" thingy out of a metal salad bowl and cut the bottom of the air cleaner from a like 3 inch radius to around 7 or 8...lot more flow!
after the tbi spacer and the bowl i tested my air/fuel ratio and it was at like .6 mV so i turned it up like 4 turns, and now at full throttle its like .9-1mV.

7. took of that heater hose that goes to the manifold and also that one for the valve cover vent...repaced it with a k&n little filter i found at my friends shop.

results...the tbi and the bowl seriously increased my mid range...its really great for off roadin now...top end felt a little flat until i put the bowl on, now it pulls like it should. gas mileage seems to have increased as well, though i have now actually counted yet. i definatly suggest doing everything how i did it if you dont have 60$ for a spacer and like 80$ for that bowl thingy.

next up..westers will flow match your injectors for 20$ each. im going to have them open them up a bit in addition to a new chip to go along with my new 360hp engine (w/o bolt ons yet) and when my engine is in the shop gettin all suped up im going to have the tbi bored and ported professionally. also found a k&n open element cone filter im going to use with a custom intake im going to make out of more kitchen metal stuff...and route the filter over to where the NBS filters are, by the grill

oh..i took off the gasket on the hood too. prolly didnt do anything except defrost my windows quicker

[Phillybets]

About to start modifications on my fuel and exhaust systems ('89 K1500). I am in the process of checking for performance parts.

Any advice on particular brands or starting points? I am going to replace the entire stock fuel, ignitiion and exhaust systems.

I was wondering also about sensor compatibility (TPS, relays and valves) that need attention during this type of upgrade.

Thanks in advance.

[kevin5.7]

how to you increase the fuel pressure?

[Chevy Dude]

On TBI units the Fuel Pressure Regulator (FPR) is internal on the TBI and the pressure is fixed at the factory somewhere between 9-12psi. There are kits on the market to convert your FPR to an adjustable one.

I purchased the one from CFM-Tech and was able to get the pressure all the way up to 14-1/2psi before I adjusted down to 13-1/4psi where it runs good at now.

[kevin5.7]

does increasing the fuel pressure increase power?

[Chevy Dude]

You need a balance of air and fuel to increase power.

I recently increased the airflow to my engine with the mods I listed in this thread and needed to increase the fuel pressure to take full advantage of them. Thus more air + more fuel = more power.

[gadzooks25]

Originally Posted by drew_motohead

6. made a "power bowl" thingy out of a metal salad bowl and cut the bottom of the air cleaner from a like 3 inch radius to around 7 or 8...lot more flow!

I need pics of this "power bowl."

[91s104x4]

go to a search engine an type in hypertech power charger

[bigredtrk1991]

Originally Posted by gadzooks25

I need pics of this "power bowl."

Here: http://www.elmnet.net/~lange_c/c1500_1.html

[gadzooks25]

Thanks for the info on the Hypercharger. I know the concept. I just wanted to see pics of this homeade one.

[fish462]

Plenty of talk in this sticky about TBI spacers. I am getting ready to order one but I'm not sure which style and brand to get. I was leaning towards the Trans-dapt TRD-2534 (slottled swirl design). In another post, I was reading where the open kind were better, like a Trans-Dapt 2634. These both run about $50.00 from Summit. I was also looking at the CFM technologies and Airaid spacers as well. These are $30 to $40 more expensive than the Trans-dapt spacers. Any thoughts?
Thanks.
Fish

1993 C-1500 Silverado 4.3L 5 Speed.

[Jhoskins]

Originally Posted by fish462

Plenty of talk in this sticky about TBI spacers. I am getting ready to order one but I'm not sure which style and brand to get. I was leaning towards the Trans-dapt TRD-2534 (slottled swirl design). In another post, I was reading where the open kind were better, like a Trans-Dapt 2634. These both run about $50.00 from Summit. I was also looking at the CFM technologies and Airaid spacers as well. These are $30 to $40 more expensive than the Trans-dapt spacers. Any thoughts?
Thanks.
Fish

1993 C-1500 Silverado 4.3L 5 Speed.

For my next modification, I have been planning on getting a spacer, I have decided on the trans-dapt, but I do like the cfm tech design although I doubt the spacer will do anything anyways, I am just gonna do the cheaper one.

Right now I am just debating on underdrive pullys or a spacer (trans-dapt). Does anyone have an opinion?

-Joe

[denmason]

I'm using the CFM TB spacer and AFPR. It made a lot of difference. I also used an injector spacer. Throttle response and exceleration increased and the motor idled much better. I also shaved the throttle body and the butterfly rod.
I'm very happy with the results, it is so easy to do. With I would have done it 18 years ago when the truck was new!