hi everyone, what kind of horsepower and torque can i expect out of my chevy 350? it is from a 1991 chevy 1500 Silverado and all i did was add an intake manifold from a 1975 chevy 1 ton, (to fit the rochester quadrate) i'm gonna get some headers that will help me out with mileage, and tune the carb down as to get good mileage. theres an SM420 4 speed transmission behind it. its in my 1953 chevy 1 ton flatbed. does anybody have any ideas as to what this will put out? and will this truck be able to get up and go? or just more of a cruzer? thanks in advance
200hp....You would be surprised how many guys, add up all the HP gains by part mfg-ers, to make a sale... Everyone has 400 + till they put them on a dyno, then the dyno was wrong....
haha, alright, thats better than the stock 120 that it made i guess, i dont really plan on doing any racing, or what-not, as long as it runs & can pull, any idea how much torque?
If mileage is a concern, the TBI engines aren't the ones you want. Even fitted with a carb they just aren't an optimal mileage or performance engine in stock form. What they did do well was produce torque to get them big trucks moving and meet the EPA requirements at the time. But if you look at hoops chart, you can see how painfully low the volumetric efficiency is. Some better flowing heads, higher compression and that will really wake things up.
You should have a lot more pulling power and a higher top speed because you not only have more HP, the engine will rev a lot higher. You will be able to haul any load you can put on the truck, plus a big trailer. Expect your comfortable cruising speed to be 50 - 55 although you might get it up over 60 if you push it. Believe me this is plenty fast in a truck like that. It should be the ideal engine for a 1 ton flatbed. Do not worry about hopping it up, what you need is torque not HP. A 350 with 4 barrel and headers is perfect.
Tbi heads are pretty much done at 4500 rpm. There's only a very small range to go higher but, they are already low on compression so moving the Rpm range up is usually an exercise in futility. With a bunch of work you can increase the volumetric efficiency of those heads in the 3500-5000 range and pick a cam to work a bit higher but it costs plenty of low end and still falls on its face over 5000 rpm. Really all this does is narrow the power band and raise the peak but lowers the average power from the engine. So any engine modifications need to be chosen that provide the most benefit in the low to mid range or it will be a waste. No secret that Low compression engines waste fuel. Short block is the same, and very capable
The HP comes from all the stickers (k&n, cam2,crane) you put on the car. Because the Dyno does not pick up stickers the dyno is wrong so the HP is off. My tool box has over 600HP!
Ain't that the truth !! Without a dyno, you can go to a track, weigh the car, get the MPH off the timing slip & calculate rear wheel hp. Add 10-20% for driveline loss and you will be close. Don't be suprised if the horsepower is much lower than you suspected. One HP per cubic inch is pretty respectable for a streetable carburated 2 valve per cylinder moderate compression pushrod V8. Even that takes a pretty good combination of parts. --- Steve ---
Have you already done this? Reason I ask is a '75 intake (or any made before 1986) will not have the center 4 holes canted at teh different angle. Either the manifold holes would need to be elongated or a swap to mathing heads and intake (both pre '86 or '87-95). Maybe you already knew this but it is food for thought. Good luck
It won't need a cat converter in a 53 truck, he can also add duel exhaust. A stock 91 Chevy truck can easily break any speed limit in North America. It's all someones definition of get up and go.
A 91 Chevy truck used a flat tappet cam. All the V8 car cams were roller cams. Chances are the block was made so it could be converted to a roller cam cheap. The factory GM roller cams are much cheaper than the aftermarket roller cams. The lifters are reuseable. It's not hard to find take out cams.
The scourge of the Sbc, the most al time hated Sbc, the boat anchors boat anchor Sbc, the redheaded step child sbc, the infamous and dreaded 307 ( one of my favorites btw) Is SOOOO despised because it only made 200 hp. With HUGE HUGE combustion chambers and*****ty compression and a 2 bbl. See... A 307 cu in (5 L) version was produced from 1968 through 1973. Engine bore was 3.875 inches (98.4 mm) with a 3.25-inch (82.6 mm) stroke. The 307 replaced the 283 (but are the same engine block with a longer stroke) in Chevrolet cars in 1968 and produced 200 hp (149 kW) SAE gross at 4600 rpm and 300 lb·ft (407 N·m) of torque at 2400 rpm in the 1960s. The later emissions-modified versions produced just 115 hp (86 kW) SAE net, giving the engine one of the lowest power-per-displacement ratings of all time. Chevrolet never produced a high-performance version of this engine, though they did produce, for Outboard Marine Corporation, a high-performance marinized 307, rated at 235 hp (175 kW) and 245 hp (183 kW) SAE gross, depending on year, that shipped with the Corvette/Z-28's cast aluminum valve covers and Rochester QuadraJet carb. Chevy also built other versions of the OMC 307 rated at 210 hp (157 kW), 215 hp (160 kW) and 225 hp (168 kW) SAE gross. I'd put a 307 up against a 350 TPI engine any day. Whoop it's**** and get twice the gas mileage.
It won't be a TPI any more if he changes it to a carb. Even Stevie Wonder could find heads and other parts to get more performance out of a Chevy 350.
Well that's just it isn't it? It's mostly in the heads. TBI heads just aren't on the "heads to avoid" list for nothing.
90,000,000 SBCs can't be wrong. A million years from now someone might unearth one like they do dinosaur bones.
that engine may get the job done as is, but if you're looking to get decent mileage too, you'll need to make some changes. Making more power will help you make mpg. I'd change the heads to a set with slightly larger valves to increase flow, smaller combustion chambers to bump compression, an economy/rv type cam, put headers and decent exhaust on it, maybe consider an intake that will allow the use of an edelbrock carb, and spend some time with the distributor tuning it all in. I would venture a guess that you would see about 300 hp and 350ftlbs torque with a simple well tuned engine with parts that work together. I know some will claim big power or lots of mileage from quadrajet carbs, and it is possible, but tuning them is a science in itself. The edelbrock is a little easier to tune for the average person and performs well under most circumstances. One thing to keep in mind is that your gear ratio and tire size will dictate your cruising rpm, and you'll want your engine to be most efficient at whatever that rpm may be.
Totally OT, but WRT to fuel mileage...I had a 91 GMC truck with a TBI 350 and 5-speed. It got better mileage with 250K miles on the clock than my 5.3 Vortec-powered 2002 GMC ever has. To the OP: it's a 1-ton truck with an SM420, not a drag car...who cares how much HP it has. It'll get up and go better than it did with stock the 6-banger.
That would be a first or there's something wrong with your 5.3. Both of my current 5.3s see 20 mpg or better and 1 is stock at 295 hp , the other is warmed up a but and around 330 hp. All of the TBIs I've owned we're lucky to break 12 mpg with a really good tail wind. 2 were the 210 hp with tad higher compression and one was the 185 hp with 8.3:1 compression.
put it in a corvette - instant 350 hp. Add a chrome air cleaner and some yellow plug wires, you're up to 500 hp.
The 1991 TBI 5-speed was still getting 18 mpg with 250K miles. I DID neglect to mention that the 5.3 is 4wd Z-71 and has a tow package. Best I've EVER gotten from it was 16.
I remember GM selling 307's for 300.00 long blocks in the crate,should have bought a stack in hind sight..
I often wondered. You sure cleared up this unsolved mystery. LoL SO my back window does have more HP then my engine.... I got it now thatnks
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