TBI 350 Power Upgrades

[dyeager535]

I hadn't looked at the L31 but I have looked at Westcoast engines. I don't need the extra power so until this engine dies, it won't be coming out of the truck. If the engine were to come out of the truck I would likely spend the money to build a 383 stroker of the engine HAD to come out.

If the plan is to keep the rig, and not go away from the Gen1 engine architecture, I'd probably not hesitate to go with headers. At least those would still be useful on the next engine. Cam and intake too, but if you were going to buy or build an engine, I don't think I'd be interested in re-using the cam, and a larger engine could probably do better with a more substantial intake than the TBI engine can use.

Of course with headers, you run into cost vs. longevity. I like my Hedman Stainless ones, but I feel like I stole them....they are around $700 new. But I'd rather not have to worry about them rotting out like all headers will eventually.

 

[aglinks]

I ordered a sample container from Blackstone Labs so I can see what type of wear the engine has. If the bottom end is still in good shape, I will start pricing upgrades. If its not, I will start savings for a new engine.

 

[1-ton]

If you do not have to worry about smogging your truck, and you have an old tired small block TBI engine, do not waist your time trying to do anything with it. The only reason I put money into a new TBI crate engine with a cam, fuel pressure regulator, and other mods for my truck is that it needs to pass smog. My new TBI crate engine with all the fuel, cam, and exhaust mods is only making about 250-HP and about 375 FT. pounds of torque.

 

[superbuickguy]

Ok that sounds like a plan. I'll start hunting for a used intake. The new ones are SPENDY! Do you use the same push rods with the vortec heads?

I didn't buy new ones - thinking whether or not I checked or simply did the glance/good enough routine. I dunno.... I do so many engines - my normal routine is felt-tip mark the intake and exhaust on #1, put the rockers on, put the rest on, adjust the valves (which means I'm turning it 720 degrees), then pull the rocker back off (now that it's back on #1) and see the wear pattern... but I wouldn't swear I did it on this one....

 

[superbuickguy]

If you do not have to worry about smogging your truck, and you have an old tired small block TBI engine, do not waist your time trying to do anything with it. The only reason I put money into a new TBI crate engine with a cam, fuel pressure regulator, and other mods for my truck is that it needs to pass smog. My new TBI crate engine with all the fuel, cam, and exhaust mods is only making about 250-HP and about 375 FT. pounds of torque.

something to keep in mind. Ever since GM started putting oil coolers on their motors, bottom ends simply don't get ridges and I've yet to find a bearing that I wouldn't re-use.... why spend the extra money? The GM, seasoned version has lasted at least a hundred thousand miles.... the rebuilt one? just a week before the "professional rebuilder" was saying "you want fries with that burger?"

 

[1-ton]

I just finished an LS swap in my CJ7 using an engine package from Tilden Motorspors. I'm looking to keep the burb as original as possible (wiring and plumbing and such) and upgrade the existing engine to put out a little more power. Maybe intake and exhaust? I'm not searching for huge gains, just that little extra bump to help the old burb up the steep grades.

An exhaust system is the easiest way to increase performance on your engine. At minimum a scavenger Y-pipe and a high flow CAT. I have intake manifolds, larger TBI, small performance camshaft, increased fuel pressure and all that stuff on my new GM Goodwrench crate TBI 350, and it does not make that big a difference I can feel. I am not saying my 350 TBI does not run real stout for a 350 TBI, but it is no "world beater" by any means.

 

[superbuickguy]

I've had a bunch of LS motor vehicles and daily drive my Hummer H3 with a 5.3 LS motor in it - but to be completely frank and run the risk of an epic fight, it's really not all that - side by side my 85 Suburban with a diesel and turbo is as easy to drive every day as my LS powered Hummer. Suburban gets better fuel economy too. The LS is a stout, stout base for race motors but in the daily-driver category it was designed so GM could pass emissions.... which usually is not the same as performance. That, again, doesn't mean it's not a world-changing, great motor... but in a pickup? it takes 2 cats per engine side to pass smog checks. The H3, on 35s, in town driving gets 12 mpg. On the highway is barely gets 14. Consider a 93 1/2 truck - if you got 12 or 14 empty you'd be looking for the cause of such terrible mpg. For apple comparison, I also own a 2004 Denali that gets 13/15 and has far more highway friendly gears.

The benefit of a Gen 1 small block is it costs less to build, less to maintain, and in anything that's running less than 500 hp is a far better choice. As I'm also building a 427 BBC Corvette - and am not using the Denali's motor - the reason is it cost about 2k less to build a BBC Corvette then put an LS in it. But then again, it's for knuckle dragging and racing - both of which defy the terms "world class" and "high tech"

As for that poor, unloved LS motor - I'm probably going to build a MB Jeep with it in it because dimensions of a side-by-side and hp of a Corvette appeal to me.

 

[thearborbarber]

I did a salad bowl, injector pod spacer, tbi spacer and a set of summit aluminum heads and no cats. After the a custom made chip I'm around the 225-230hp area based on trap speed and 1/4 mile time.

 

[aglinks]

I did a salad bowl, injector pod spacer, tbi spacer and a set of summit aluminum heads and no cats. After the a custom made chip I'm around the 225-230hp area based on trap speed and 1/4 mile time.

Is that at the tire?

 

[thearborbarber]

I wish, estimated at the crank. Here is what is at the wheels;

 

[dyeager535]

I did a salad bowl, injector pod spacer, tbi spacer and a set of summit aluminum heads and no cats. After the a custom made chip I'm around the 225-230hp area based on trap speed and 1/4 mile time.

Is the chip dialed in good? That isn't much of a gain over the 190 stock, if the heads are worth anything. No headers?

Kudos for taking the time to get real numbers.

 

[aglinks]

I really thought the Summit Racing heads would have made a larger difference.

 

[Greg Ducato]

I have done the whole TBI bolt on mod thing on two of my past square bodies, a Blazer and a Suburban. Both received Thorley tri-Y headers into a 3 inch single system, Edelbrock TBI intake, GM performance parts distributor, Ported throttle body, increased fuel pressure, Injector spacer, salad bowl mod to air cleaner with K&N element and custom computer chip.
There was a noticeable uptick in performance, I would estimate at least 20-25HP across the usable RPM range, and it did make the hills a little flatter. I was fortunate to have found the headers and intakes at used prices instead of new so that helped, But I still had over $1600 in each set up including simple exhaust. If I am ever faced with this scenario again I will do what many recommended to me and perform an engine swap.

 

[thearborbarber]

Stock cam and exhaust manifolds are what are holding it back now. According to my scanner and wideband O2 the chip is right on. The summit heads were the most noticeable improvement. My goal was to be able to drive 70-75mph down the interstate with the ac on and tc locked in OD. Mission accomplished. Plus it's easier to pass since the swirl port heads ran out of air around 3500rpm-ish.

 

[aglinks]

Throw some long tubes on there and dyno it again! haha

 

[sreidmx]

I've got one of these in the wife's 92, it downshifts on hills, makes a bunch of noise and goes nowhere.. I've got shorty headers, completely open exhaust albeit the stock y pipe, but no cats with a flowmaster, its chipped, has a built 700r4 and highway gears. It cruises great under 3500 rpm, anything above that it's a joke. Laughable for a sbc, put some kind of cam in it.. if the oem ecu doesn't like it put a megasquirt on there, it's far more tweak friendly and they make a direct drop in harness.
@secutright has on on his blazer and it's a beast for a pretty stock bottom end with a cam/springs and intake, headers. It makes power all the way through. With worse than swirl port heads.. if you are steadfast in your gen 1 motors..
your argument against the small Ls sounds primary related to the stock motors, nothing done etc, and as far as how clean they are and how many cats they need is because the emissions standards got way worse after 2000 that's why there is more stuff there, not because the Ls is a dirty motor.. high strung yea, duh 18 degree heads, big ports compared to the l31 or any sbc derivative.

 

[aglinks]

I LOVE the LS I put in my jeep. I just really don't want to do an engine swap. And since I'm not looking for insane power gains I don't think I'm being too hard headed.

 

[sreidmx]

I LOVE the LS I put in my jeep. I just really don't want to do an engine swap. And since I'm not looking for insane power gains I don't think I'm being too hard headed.

I think your in the range but ditching the stock intake and cam will turn it back into a sbc if you have al heads already

 

[dyeager535]

Stock cam and exhaust manifolds are what are holding it back now. According to my scanner and wideband O2 the chip is right on. The summit heads were the most noticeable improvement. My goal was to be able to drive 70-75mph down the interstate with the ac on and tc locked in OD. Mission accomplished. Plus it's easier to pass since the swirl port heads ran out of air around 3500rpm-ish.

Are your heads considered Vortec equivalents or better? What's the TBI cam look like compared to the L31?

I suppose looking at it holistically, you aren't too far off the L31 power numbers, especially being TBI instead of sequential, and flat tappet instead of roller. But headers alone would almost certainly put you at or very, very near the L31 base HP number.

It would be nice to have the resources to be able to do one thing at a time (heads, intake, cam, headers) and in the various combinations that would enable.

 

[thearborbarber]

These are the heads. Rumor has it they are reboxed dart heads

https://www.summitracing.com/parts/sum-162109

Stock TBI cam is .050″ tappet lift (intake/exhaust) is 165/175; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is .382/.402

I like the tbi system, it's simple and I have a pretty good working knowledge of it. Parts are easy to find still. I have a 454 tbi coming soon. It might go on with a new cam.