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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!
In the T-Ram vs. TPI, Dyno Results.... AKA, "10 times the tork, Take Too", the thread got a little off track on page 3 about engine weights....
Originally Posted by Fast355
L33 or other aluminum 5.3L would take over 100 lbs off it compared to an all-cast iron small block. Then again, a newer 4.3L direct injected V6 based off the L83 5.3L or L86 6.2L makes a stupid amount of power for a V6 when it has a mild cam. Both might be a chore to hook to an earlier manual trans though. The little LV3 4.3L made 368 hp at the crankshaft with a 210/223 @ 0.050 cam!
Originally Posted by Tom 400 CFI
Yeah.... no.
It's a 'Vette, so it's got aluminum heads....not "all iron", and that won't save 100 lbs. Still, it will save some weight, so I do I think about an aluminum LS...maybe some day, but that doesn't really fit the budget for this project. Maybe someday.
No V6's. Sound is part of the experience. That 368 GROSS is probably pretty close the the ~300 NET that I'm already making. No, no V6's in this car. Just like the C4 did, I reject a V6 solution.
Originally Posted by QwkTrip
I don't know real numbers, but I was under the impression aluminum LS vs. iron block LS was ~100 lb difference, and that an iron block LS was similar weight as an aluminum headed SBC. And the center of gravity of an LS is a little rearward. All I know is I had to re-adjust the front springs on my car when I swapped from iron LS to aluminum LS because the nose rose so much from the weight loss.
Originally Posted by Tom 400 CFI
IDK...Engine weights are pretty hard to come by on the 'net, b/c there are so many ways to configure any engine, before weighing it. Numbers are all over the place. I thought an aluminum head L98 is about "high 400's" and most any aluminum LS was about 450.
Originally Posted by Fast355
Iron block with aluminum heads weigh very close to the same either way. I just weighed the LQ4 I pulled out of the 87 G20 prior to selling it. The L31 350 is 30 lbs heavier with iron heads. The iron block 6.0L block itself is 216 lbs. Both engine were fully dressed at the time. 6.0L had long tubes and the 350 has cast iron manifolds.
Originally Posted by Tom 400 CFI
See? ^^^
Very hard to compare anything.
So what do any of these engines actually weigh? I can't tell. An L31 weighs 30 lbs more than an LQ4? What's THAT weigh? Who knows. Sounds like the LQ4 (bare?) block weighs 216? Who knows. I don't. And in what configuration?
And ^that^ conversation is pretty darned typical of any you find on the forums about engine weights....all over the place. Since I'm changing the Turd engine in the Grandpa truck, L30 to L31, I figured I'd weigh it and then? Hard data. We'll KNOW. Also, I have the L98 out of the Kart, so I'll get that one, too (DONE. See post 13).
Anyway, here is the L31, first, long block + intake. No flywheel, b/c we never know what FW someone will use. That's part of the transmission. So, you could take this base line and add what ever your choice of accessories and headers are....otherwise, this measure is pretty useless. I WAS surprised, however, that it was well under 450. Short tube headers, mini starter, aluminum WP and an alternator and you'd be real close to 450...with an "all iron" gen 1 SBC. Not bad, IMO...
OTOH...an L31, IMO, is an RPO for a complete engine package and includes exhaust manifolds, all accessories, starter, iron WP....and all of that junk adds a significant amount of weight. 115 lbs, in this case......
Last edited by Tom 400 CFI; Aug 16, 2025 at 09:03 PM.
Back when I started my LS swap I had a few mills sitting around. I weighed a stock bare LQ4 block and a stock LS1 block and there was almost an exact 100lb difference. The iron mill was 200ish and the aluminum unit was like 98lbs. I have an old GM spec sheet and it says engine and accessories for the L03 is 550lbs. TPI was similar but I'll circle back and post a screenshot of it. Tom's L31 weight checks out.
Wish I could have weighed my BBC. Lots of iron in it but aluminum heads and tunnel ram help reduce weight.
Best guess would be around 600 pounds but it also doesn't have a whole lot of accessories on it. Alternator, vacuum pump, belt driven fuel pump. Lots of aluminum brackets.
My car is still nose heavy but produces enough torque to pull the front wheels past the 60' timer.
There was a good thread on speedtalk with a lot of weights. See if i can find it
i can confirm ls aluminum block is easy to pick up and carry. An iron sbc or ls is much harder lol i still could pick them up and get them in the truck bed. The iron dart bbc block i could not haha
Totally useless info,
I picked up a intake to oil pan pontiac engine from the ground and put it in the back of a pickup truck by myself back in the day. About 600-650lbs.
Used to be somewhat strong
In the T-Ram vs. TPI, Dyno Results.... AKA, "10 times the tork, Take Too", the thread got a little off track on page 3 about engine weights....
So what do any of these engines actually weigh? I can't tell. An L31 weighs 30 lbs more than an LQ4? What's THAT weigh? Who knows. Sounds like the LQ4 (bare?) block weighs 216? Who knows. I don't. And in what configuration?
And ^that^ conversation is pretty darned typical of any you find on the forums about engine weights....all over the place. Since I'm changing the Turd engine in the Grandpa truck, L30 to L31, I figured I'd weigh it and then? Hard data. We'll KNOW. Also, I have the L98 out of the Kart, so I'll get that one, too (shortly).
Anyway, here is the L31, first, long block + intake. No flywheel, b/c we never know what FW someone will use. That's part of the transmission. So, you could take this base line and add what ever your choice of accessories and headers are....otherwise, this measure is pretty useless. I WAS surprised, however, that it was well under 450. Short tube headers, mini starter, aluminum WP and an alternator and you'd be real close to 450...with an "all iron" gen 1 SBC. Not bad, IMO...
OTOH...an L31, IMO, is an RPO for a complete engine package and includes exhaust manifolds, all accessories, starter, iron WP....and all of that junk adds a significant amount of weight. 115 lbs, in this case......
The 417 block L31 I weighed with a PMGR starter, GM AD244 alternator, a 4261 Sanden SD7H15, PS pump, water pump, with an aluminum Proflow 4 4150 intake manifold was right around 550 lbs. So that checks out with what I saw. The LQ4 was around 520. That deep skirted LS iron block cost you a bit in weight compared to a traditional small block or an all aluminum LS block.
A lightweight cast iron SBC head is about 48 lbs. That would ve 416s, 601s, 081s, 083s, Vortecs, etc. A 113 aluminum head is just under 25 lbs. Your Vettes L98 should be about 40 lbs lighter than the L31 assuming it has a LTR TPI intake on it. The TPI intake is substantially heavier than the L31 truck intake because of the high percentage of plastic content in the Vortec intake. I suspect the Corvette exhaust manifolds are a bit lighter as well. I could see your L98 down around 500-510 fully dressed.
Back when I started my LS swap I had a few mills sitting around. I weighed a stock bare LQ4 block and a stock LS1 block and there was almost an exact 100lb difference. The iron mill was 200ish and the aluminum unit was like 98lbs. I have an old GM spec sheet and it says engine and accessories for the L03 is 550lbs. TPI was similar but I'll circle back and post a screenshot of it. Tom's L31 weight checks out.
I weighed a LQ4 block with main caps, cam bearings, all coolant jacket plugs and main cap bolts at 216 lbs right before I put it on the stand to build it.
Back when I started my LS swap I had a few mills sitting around. I weighed a stock bare LQ4 block and a stock LS1 block and there was almost an exact 100lb difference. The iron mill was 200ish and the aluminum unit was like 98lbs. I have an old GM spec sheet and it says engine and accessories for the L03 is 550lbs. TPI was similar but I'll circle back and post a screenshot of it. Tom's L31 weight checks out.
Years ago I saw a quoted figure from GM Performance that a LS1 with production dress was 460 lbs.
What's that mean? FW? Manifolds? Which car was the LSI dressed for?
I'd bet that the L98 sitting in my garage is w/in 30 lbs of that.
It means it was a fully dressed engine like came down the assembly line to be placed in a C5. Drop it in a car, hook up the hoses, bellhousing, exhaust, intake duct, harness and it runs. The manifolds, accessories, even drive belts came on that engine assembly. It was for an Automatic Corvette and included the flexplate. The manual transmission engine weight included the weight of the flywheel and clutch. IIRC it was 457 lbs for the automatic and 499 lbs for the manual trans, been a few years since I have seen that spec sheet but I know I am close.
I think you will find that L98 more like 500-510 if it is all there. Manifolds, accessories including the smog pump, factory TPI intake (suckers are heavy), etc.
It means it was a fully dressed engine like came down the assembly line to be placed in a C5.
Copy. You didn't include that information, above. LS1's came in different cars, with different "accessories" (exhaust manifolds, at least) plus the flywheel that you mentioned, finally. That stuff makes a diff, hence my question, so thanks for filling in the blanks. The flywheel is part of the transmission.
Originally Posted by Fast355
I think you will find that L98 more like 500-510 if it is all there. Manifolds, accessories including the smog pump, factory TPI intake (suckers are heavy), etc.
Yeah? I..D...K...
Originally Posted by Fast355
Years ago I saw a quoted figure from GM Performance that a LS1 with production dress was 460 lbs.
Originally Posted by Tom 400 CFI
I'd bet that the L98 sitting in my garage is w/in 30 lbs of that.
To be a "real" L98, it's missing the smog pump, A/C Compressor and PS pump (13 lbs with fluid in it) and whatever the difference is with the intakes; I don't think the TPI intake is as heavy as Fast is making it sound....and I just swapped 7 intakes on this thing so....I pretty well know about what each weighs, relative to the others....TPI was not the heaviest.
Anyway, I feel pretty good about a 'Vette (113 head/fabricated manifolds) L98 weighing w/in 30 lbs of the claimed LS1 weight above....and that's a data point that puts the "go LS to save weight!"...to bed in my mind. I've been skeptical of that for a long time and now? Confirmed. An LS swap won't save me "100 lbs".
Last edited by Tom 400 CFI; Aug 18, 2025 at 07:00 PM.
