TBI swapout, need more power

The biggest restrictors on the TBI engine are TBI unit, intake manifold, heads and cam...Nothing major...hehe...he...

Get the Edelbrock performer Multi-Point EFI System(PN 3502). It uses your stripped down TBI unit. You will need some fuel line mods and a new fuel pump, but the gains are worth the work and cost. A CompCams Xtreme 4x4 cam/lifters(PN CL12-235-2) is a good choice for a cam(even with the factory TBI). A set of World Products S/R Torquer heads(PN 042770-1) would bring everything together(cam and MPFI). You will definatly need a custom PROM before this point. A set of headers, high flow CAT, and 3inch single exhaust with a high flow muffler would allow everything to reach its full potential.

Before the exhaust, the scales will tip past $2000, but its all something that can be done in your driveway with the engine still under the hood. The MPFI would be the first, cam and custom PROM second, then heads and exhaust with a new custom PROM programming.

"The Engine just isn't putting out the power it should " My first thought is that if it isn't putting out the power that it should then you need to diagnose the problem and fix it before considering modifications.Compression is good,what about valve lift? Valve timing? Have you checked the plug-wires? Cap+rotor? etc.-

put a supercharger on it ...

try some basic tune up items first...platinum plugs high quality wires, cap, rotor....try a throttle body spacer...open up your exhaust, hi flow cats, larger diameter dual exhaust...if you don't want to make alot of noise,Magnaflow makes some nice hi flow mufflers that are more bite than bark...try bumping your base timing up a few degrees...i run mine at 6 on an 89 chev 4x4...go to a local repair shop and see if they have a motor vac machine[goto

Ok, now im getting curios. I did a search on TBI to find this post I started. First i'll answer some questions: Yes I upgraded the wires, cap rotor and put in platinum plugs, that's when I checked the compression. I haven't heard a thing about the replacement Holley TBI units, ads say they are the way to go, but I haven't heard of any one actually using one. When I run the engine with the air filter off I can see some pretty thick streams coming from the injectors so I know they need replacement. I upped the timing to 5 degrees, yes with the correct cable unplugged to shut off the electronic advance, any more and it starts to ping. Now the questions: how do I tell what heads are on it. Originally this was a special order truck with major options like a transmission oil cooler, larger radiator... the original owner purchased it to tow a big, BIG, boat. If it has 194 heads I'm fine with sticking with the same heads. But how can I tell what heads are on it. Also in another post I read about an Edelbrock kit that comes with heads, cam, intake... Hmm I just don't want to replace the heads it I don't really need to.

Thanks

Original TBI heads don't flow good. Most people that I know that have tried the Holley TBI on a stock engine haven't liked it due to the restrictive nature of everything after it. I have known guys that have tried intake, TBI, and head upgrades but kept the stock cam and had a loss of power and MPG until they upgraded the cam. A cam only upgrade helps, but not as much as it could.

You need to measure the valve lift and the valve timing for starters. Don't even consider mods until you have done this. If you have a worn timing chain with lots of slack and a severely retarded valve action,and the valves aren't opening all the way due to rounded off lobes on the cam you will have major power loss.The solution would be to install new cam/lifter set and chain,NOT add some expensive intake system. If that's NOT the problem start checking other things,engine vacuum, do a leak-down test,exhaust analysis, exhaust back-pressure etc

Greetings,

First let's go on the presumption that your engine is in good condition and as near stock performance as good maintenance will keep it. Maybe you should be looking for the reason why you feel it isn't giving you the HP you want before throwing money at the motor. In '92 I believe the 350 with TBI put out about 210hp at sea level, but as we all know you lose a certain percentage of power as you gain altitude due to the thinner air so at 8000' you're starting out at a loss.

At 65 with normal load (not towing or climbing a hill) you probably are turning about 2200-2500 rpm in overdrive. This is not the "sweet spot" for power from that motor so maybe you should be thinking about dropping out of OD and into Drive (or out of 5th and into 4th if you have a manual) and letting the motor spin a little faster where it makes more power. It'll drink more gas but 2800-3000 rpm won't hurt the motor when cruising.

Are you running oversize tires? If you are, then this may also be a reason why your motor feels anemic as oversized rubber changes your final drive ratio and makes the motor spin slower for the same speed. In addition, what is your rear axle ratio? A higher numerical ratio (like 3.73 or 4.10:1) will decrease your mpg on the highway but will give you a feeling of more power because your motor will be spinning where it makes more power. A lower ratio (like 3.08 or 3.42:1) will get you better mpg on the highway because your motor is turning slower but you sacrifice power and towing. Perhaps what you are experiencing is nothing more than a gearing issue, especially if this truck was meant more for the flatlands than the mountains when it was put together.

The basic rule of generating more power is "Air In/Air Out". Intake and exhaust mods are always popular, but if you really want to cram the air into the cylinders (especially at high altitudes) then you should be thinking something like a turbocharger or some type of blower down the line along with whatever else you want to do.

Cheers - Jonathan