Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
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I have heard that either hot rod or chevy high performance has made this swap with tremendous results:
They took a stock Vortec motor out of a junk yard with 110,000 miles and put it on a camaro. The dyno results were like 290 hp. They then swapped the cam with a stock lt1 cam and made 100 more hp!
Is this something anyone is familiar with?
What mods would have to be made to the Vortec heads to be compatible with an lt1 cam? Would this be worth trying? If not, what would be a better cam upgrade than the lt1?
I follow both magazines, but I haven't heard of that. Maybe I missed it? Anyway, those results sound optimistic. getting 290 crankshaft horses seems realistic, but if it was tested in the car, they weren't able to measure crank HP. 100 HP for the LT1 cam, didn't happen. Maybe with the LT4 HOT cam, but that's already known to be good for a 400 hp Vortec 350. The LT1 cam is a relatively easy installation, it's a cam that is easy to live with, but if you want the LT4 HOT cam, you'll need to pay attention to the valveguides, they're too tall.
I would think that since Vortecs are truck engines, designed for low rpm toque & LT1s are designed for higher rpm horsepower, the combination wouldn't be all the effective.
Subscribing to hear. And off on today's quest to find online which magazine mights said that!
Stephen, consider first how the truck Vortec 350 was rated at 255 hp at 4600 rpm, so 290 with headers seems easy. Second, those heads are the same ports and chambers as the iron LT1 heads from the Impala SS, which were designed after the aluminum LT1 heads, so they're actually better.
Stephen, consider first how the truck Vortec 350 was rated at 255 hp at 4600 rpm, so 290 with headers seems easy. Second, those heads are the same ports and chambers as the iron LT1 heads from the Impala SS, which were designed after the aluminum LT1 heads, so they're actually better.
I didn't say anything about horsepower & headers. There is no doubt in my mind, that headers overs truck manifolds would really open up the exhaust & allow the stock engine to breathe MUCH better & increase its hp output.
Are you saying that Vortec heads are simply iron version of aluminum LT1 heads? The Imp is a heavy pig as well, so I would expect it to have more of a torque-based cam as well. A LT1 cam might help in the upper rpm airflow department, but the Vortec intake is a truck intake, again aimed towards lower rpm torque, right? High rpm cam under a low rpm intake, doesn't sound like the best combination. Bad? Maybe not, but maybe could be better.
Noone has yet told me what intake was used for testing, but it was most probably an Edelbrock Performer RPM AirGap Vortec, and that's good past 500 HP. The LT1 Impala was heavy, and it did have a milder cam than the Camaro, but it was still rev-happy. Even the truck Vortec 350s really feel asleep until you get above 2500 rpm. These heads are based on, but are better than, the aluminum LT1 heads. The LT1 in the Camaros was rated to give peak TQ at 2400 rpm, and having owned one, I can verify it's working well from 2400 rpm on up. My LT1 was reprogrammed with a Hypertech, and pulled happily to 6200 rpm, with NO other mods. Then I tried a 2400-stall converter and had an instant traction problem, despite the rear-heaviness of it being a convertible, and the gearing disadvantage of a 2.73:1 posi that worked. So it's a good cam for the heads, if you want a broad powerband and maybe 340 HP with headers and an RPM AirGap. Take a Vortec 350, at stock 9.1:1 compression, wth long tube headers, the RPM AirGap, and the LT4 HOT cam kit, you'll get 401 HP at 5600 rpm, and 428 ft-lbs at 4200 rpm. The powerband still starts around 2500 rpm.
In my eyes, it isn't a 'Vortec engine' anymore. Just a Vortec HEADED carb engine. Totally different.
I was talking bone stock, FI Vortec engine, with a LT1 cam in it. No other changes. Swapping to a carb & that kind of intake, completely changes the outlook on the whole thing.
The truck intake is very restrictive, and needs extrude-honed. But you can't upsize the injectors, and the stockers won't support that much power. There's no way they reached 390 HP with that combo. Not without a wet nitrous system, anyway.
How much did you have to change to use the lt4 hot cam? Did you buy the kit from gm performance?
What all went into this swap?
PS. My 91 camaro is basically the same set-up as yours: 350 out of a stock truck, Vortec heads, and carbed. I have a 6 speed tranny with a 10 bolt 3.42 out of a 4th gen Camaro.
I didn't say anything about horsepower & headers. There is no doubt in my mind, that headers overs truck manifolds would really open up the exhaust & allow the stock engine to breathe MUCH better & increase its hp output.
Are you saying that Vortec heads are simply iron version of aluminum LT1 heads? The Imp is a heavy pig as well, so I would expect it to have more of a torque-based cam as well. A LT1 cam might help in the upper rpm airflow department, but the Vortec intake is a truck intake, again aimed towards lower rpm torque, right? High rpm cam under a low rpm intake, doesn't sound like the best combination. Bad? Maybe not, but maybe could be better.
I actually had that exact combination in my 97 3/4 ton 4x4 a few years back.Stock vortec 350,with flattop pistons,and an LT1 cam,vortec intake,the whole works.I used the truck as a daily driver and as a tow rig.While I won't say that it was the "perfect" cam,it worked really well.
The reason I tried it,was that the original engine let go,and while rebuilding it,I did a HOT cam swap on a 95 Z28,so I figured I give the stock LT1 cam a try.It ran/pulled better than stock,but it would be safe to say it was only good for maybe 15-20HP.Mind you,the truck had 4.10 gears,but it never lacked any torque,and pulled like a freight train when loaded hard.
I actually had that exact combination in my 97 3/4 ton 4x4 a few years back.Stock vortec 350,with flattop pistons,and an LT1 cam,vortec intake,the whole works.I used the truck as a daily driver and as a tow rig.While I won't say that it was the "perfect" cam,it worked really well.
The reason I tried it,was that the original engine let go,and while rebuilding it,I did a HOT cam swap on a 95 Z28,so I figured I give the stock LT1 cam a try.It ran/pulled better than stock,but it would be safe to say it was only good for maybe 15-20HP.Mind you,the truck had 4.10 gears,but it never lacked any torque,and pulled like a freight train when loaded hard.
I have the hotter Production LT4 camshaft in my 1997 Express G1500 Conversion van. L31 350 Vortec, 0411 PCM swap (DIY Tuned) and the stock drivetrain. Its only up maybe 40 FWHP over stock and thats a hotter cam and PCM tuning.
How much did you have to change to use the lt4 hot cam? Did you buy the kit from gm performance?
What all went into this swap?
PS. My 91 camaro is basically the same set-up as yours: 350 out of a stock truck, Vortec heads, and carbed. I have a 6 speed tranny with a 10 bolt 3.42 out of a 4th gen Camaro.
this should answer most of your questions. Let me know if you need anything
