Engine swap help...

[Cadillacmak]

The intake manifold used on the Ramjet 350 combined with the 1.6 rocker does even better than the long runner truck/marine crossram manifold.

I gained over 40 ft/lbs at the tires across a broad RPM tuning a stock L31 350. At 1,500 rpm it gained 60 ft/lbs.

I like the flat torque curves like that, I don't want to pull a grade doing 6000rpm all the way up like the 2 fords I had.

 

[L31MaxExpress]

I like the flat torque curves like that, I don't want to pull a grade doing 6000rpm all the way up like the 2 fords I had.

You would love my 383s torque curve then. At 3,400 rpm the lowest the dyno would load it, it had 501 ft/lbs. At 3,700 it made 520. It carried over 500 ft/lbs past 4,800 rpm and made 502 hp @ 5,500. I am changing the cam, should be less peaky and broaden the curve while giving it better drivability. Pulling an 8K enclosed trailer behind a 7,000 lbs van it will pull a 5-7% grade at 75 mph with the converter locked in 3rd gear at 2,850 rpm. 3.73 gear and a 30.5" tall rear tire. It almost does not care that the trailer is back there in 3rd gear.

 

[0xDEADBEEF]

All I got that from was modifications can make power. No kidding.

 

[L31MaxExpress]

All I got that from was modifications can make power. No kidding.

My take away is that a larger 23* head Gen 1 engine has the ability to make big off-idle and midrange torque numbers which is actually what moves a heavy truck with less than ideal gearing. Been my complaint all along with the LS and LT engines. If I were swapping a newer engine in today in 2024 it would not be less than a L8T 6.6L and it would either have a 6L90E or 10L90E behind it.

By the time you cam a L83, put a looser converter behind it and regear, you could have put a L8T in with some long tubes and had more power and much more torque from the stock L8T. Atleast some of the L8Ts do not have the junk VFM lifters either.

 

[L31MaxExpress]

This is why I like the L8T, look at that stock torque production. Also no VFM lifters to fail. It has a 10.8:1 compression ratio and forged crank from GM as well. Long tube headers and a good tune would likely have this over 500 ft/lbs.

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[L31MaxExpress]

I will also add that the GM L8P crate engine is a L8T with a LT2 camshaft. With the LT2 cam and long tubes the power increases from 401/464 to 523 hp @ 5,800 and 543 tq @ 4,600. That is stout for a basically all stock GM small block.

If the L8Ts had been available for the price they are now with basically no mileage on them when I built my 383 my 97 Express would likely have one in it instead of the 383 backed to a 6L90E or 10L90E.

This is the L8P dyno chart. Again nothing more than a LT2 camshaft in a L8T and long tubes. Even with accessories on it this would be around 500 crank HP.

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This is what a LT2 cam cost. Huge gains for such a modestly priced cam upgrade.

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[smdk2500]

Yeah, I was probably 80 lbs lighter back then. Trying to get back there.

Yeah I wish I was 80lbs lighter. Its so easy to gain it but 10 times harder to loose it and its worse the older you get. I wish I could go back and slap my younger self and tell me to take better care of myself.

 

[0xDEADBEEF]

My take away is that a larger 23* head Gen 1 engine has the ability to make big off-idle and midrange torque numbers which is actually what moves a heavy truck with less than ideal gearing. Been my complaint all along with the LS and LT engines. If I were swapping a newer engine in today in 2024 it would not be less than a L8T 6.6L and it would either have a 6L90E or 10L90E behind it.

By the time you cam a L83, put a looser converter behind it and regear, you could have put a L8T in with some long tubes and had more power and much more torque from the stock L8T. Atleast some of the L8Ts do not have the junk VFM lifters either.

VVT, 11:1 compression, and DI also make low end torque ... without tradeoffs.

The L8T is great with inherent extra 1.3L advantages, but I don't think you're finding one at 5.3 prices.

 

[L31MaxExpress]

VVT, 11:1 compression, and DI also make low end torque ... without tradeoffs.

The L8T is great with inherent extra 1.3L advantages, but I don't think you're finding one at 5.3 prices.

Factor in the fact any 5.3L is going to have a ton of miles on it to be cheaper and likely need lifters, puts the L8T in the same ball park. Especially if you plan to use the newer transmission and over 140K miles on a 6L80E is on borrowed time without a converter replacement. I have seen multiple L8T and 6L90E or 10L90E pullouts here local for $4,000-6,000 with under 20,000 miles on them.

Here is one for $4500 with a 6L90E for $1500 both from a 15,000 mile truck.

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[newby96]

I got my 2015 gen V 5.3 from a buddy. Has 140k miles. Got it for $50. Lol

Now for being gutless, I have a 2014 ccsb silverado with a 5.3. That thing runs better than my 2007 6.2 escalade. Only reason I'm even considering the swap. I'll do all good upgrades on engine of course before it goes in truck. Truck is project I'm working on right now. Pics of truck how it sets. And of gen V 5.3 I have.