Engine weight question: 13b, LS1, etc

"pianomanzero" (pianomanzero) 08/05/2013 at 01:18 • Filed to: Ask Oppo

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I was talking with a friend tonight about cars and he had mentioned he wanted to do swap a LS1 engine into an RX-7 or BMW E36.

I posited that, while I had heard of both swaps being done, I might be a little hesitant about such a heavy engine in either car doing damage to either cars' handling capabilities.

While I have a lot of experience pulling and rebuilding various engines, I don't have ton of rotary experience (my experience is limited to helping a friend pull a 13b out of a wrecker), I have done a fair amont of American V8 work with my dad and the 13b felt loads lighter to me (at least as I remember) than even the smallest V8s I've worked with.

I know there's a fair amount of info out there about RX-7 V8 swaps, but some of their information and information on various other forums seems to conflict a bit.

Has anyone out there in Oppoland had first hand experiences with either of these swaps? Does swapping the V8 into either car damage their handling like I think they might, or am I thinking totally wrong?

The Opponaut formerly known as MattP123 > pianomanzero 08/05/2013 at 01:29

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First hand experience? None. The LS1 is all aluminum, so I imagine it is fairly light. I remember a friend of mine who was big into the Japanese sports cars saying the LS1 was sometimes lighter than the cast iron 4 cylinders they might replace. Hell, I'm sure the LS1 is lighter than the ingot it replaces in a Fiero swap. I imagine anyone who is doing a build serious enough to include any engine swap at all would also be planning on doing suspension mods as well.

beardsbynelly - Rikerbeard > pianomanzero 08/05/2013 at 01:58

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http://www.norotors.com/index.php?topi…

This guy weighed (as fully dressed as you can get) LS1 vs the NA 13b inc transmissions and sub-frames, weight difference is only 115lbs,

so it looks like a 13b twin turbo setup with associated manifolds and cooling would be heavier than the LS1


A lot of guys who've done the LS1 swap in the RX7 reckon they can still get 50:50 weight distribution.

legory > pianomanzero 08/05/2013 at 04:14

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If he does put an LS1 in an RX7 I automatically hate him.

j.davism5 > pianomanzero 08/05/2013 at 04:54

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I guess some people just want to watch the world burn. But that's okay, there is a special place in hell reserved for people that put LS1's in non GM products.

BiTurbo228 - Dr Frankenstein of Spitfires > j.davism5 08/05/2013 at 05:34

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Agreed.

For some reason, I find that MX-5s are exempt from this rule (although I'd prefer a rotory swap). I understand that that's conflicting, but for some reason it doesn't strike the chord that says 'just wrong' in my head.

j.davism5 > BiTurbo228 - Dr Frankenstein of Spitfires 08/05/2013 at 06:57

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actually, considering the premise of the mx5, this sort of swap is wrong. I'm going to go out on a limb here, and say that, as much as I love Max Orida's IS-F 2UR powered GT86, it's wrong too. The premise of both cars is to be a an exploitation of both chassis and driver at low grip/power thresholds. To add masses of power defeats the purpose, and dilutes the pure and visceral experience of pushing a finely tuned package to its limits.

BiTurbo228 - Dr Frankenstein of Spitfires > j.davism5 08/05/2013 at 07:07

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I get what you're saying. There's two classes of engine swap, one that makes something more of what it was already, and one that makes something entirely new.

Personally, I'm not overly concerned with the original premise of a car that's undergoing an engine swap. It's nice if it's a continuation of the car's original purpose, but it's not necessary for something to seem 'right'. It just needs to 'fit', and I've had a lot of difficulty defining what makes something 'fit'.

Yowen - not necessarily not spaghetti and meatballs > legory 08/05/2013 at 08:46

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hate is such a strong word. At the end of the day he'll have done a motor swap, a motor that doesn't normally reside in either of those cars, anyone that pulls that off deserves some, actually... a lot of credit.

daender > pianomanzero 08/05/2013 at 09:44

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I'll second beatsbynelly's post, a fully dressed LS weighs nearly the same as a rotary. Now then, I know of a local Mazda race shop in my area called Panic Motorsports. They specialize in two Mazdas, RX-7 and Miatas. The owner sells the rotary engines and transmissions to Puerto Rico and installs LS engines in customers FD's. One of his customers kept his rotary twin-turbo engine and went off to a track day against the shop owner's personal LS FD, the rotary let go after about 8 hot hard laps. That's one advantage the LS has over the 13b, it makes lots of torque and power without breaking a sweat and without boost (also never have to worry about apex seals). In fact, Panic's owner is going to enter his personal v8 FD into an endurance race this fall (he wrote it off it in the rain so it's all racecar from there on). They appear to know what they're doing because their Spec Miata took first in its class (people were saying a Miata would never win) at the same endurance race last year and is highly competitive in races all along the east coast.

legory > Yowen - not necessarily not spaghetti and meatballs 08/05/2013 at 13:22

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I only like people who have RX7s when they have rotaries in their RX7s.

Yowen - not necessarily not spaghetti and meatballs > legory 08/05/2013 at 13:28

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I only like people who have houses when they have blue doors on their houses.

legory > Yowen - not necessarily not spaghetti and meatballs 08/05/2013 at 13:48

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Well there you go.

Sparf > pianomanzero 08/05/2013 at 15:08

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Tell your friend to stay the hell away from the RX-7, it's been done to too many cars already and at it's beginning to affect the availability and prices of pure ones. If he absolutely MUST have one like that, then buy one that has already been violated.

There are only a handful rotary production cars, and an near-infinite amount of piston engine ones (including E36s). Tell him to go desecrate the latter if he absolutely MUST do the swap himself.

Yes, I do feel strongly about this.

Ein Reich! Ein Volk! Ein Rotary Engine!

!!! UNKNOWN CONTENT TYPE !!!

j.davism5 > BiTurbo228 - Dr Frankenstein of Spitfires 08/05/2013 at 16:05

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Yeah, it's funny really. For me, focused driver's cars that I don't understand people messing with. Over here, I've seem people chuck LS7's in to commodores or HSV products, and I get that. The car is not really anything to anyone other than a parts bin special to make it out perform it's standard brethren. I've seen VL commodores with RB26DETT conversions, and that makes sense. I have a friend putting a 6.6 duramax diesel into his 100 series land cruiser. But putting an LS1 into an RX7, or putting an LS1 or a coyote 5.0 into an NSX? Go to hell, go directly to hell, do not pass go, do not collect $200.

BiTurbo228 - Dr Frankenstein of Spitfires > j.davism5 08/05/2013 at 17:00

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"But putting an LS1 into an RX7, or putting an LS1 or a coyote 5.0 into an NSX? Go to hell, go directly to hell, do not pass go, do not collect $200"

Agreed. Automotive hell as well, which is being stuck in perpetuity behind a driver wavering between 10 and 15mph below the limit on a beautiful driver's road and being unable to pass.

I've just had a thought about what makes the best engine swap (or even modification project) for me. If, during the time the car was being produced, there was an after-hours skunkworks at the company, what would they have produced?

They'd use bits from the parts-bin as much as possible, so that takes care of 'keeping it in the family'.

If they wanted it to go on sale, they'd keep it somewhat usable. No excessive horsepower outputs By all means, they could make it bonkers if they wished, but no 500bhp V8s in MGBs for instance.

j.davism5 > BiTurbo228 - Dr Frankenstein of Spitfires 08/05/2013 at 22:07

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you're bang on to it there! The best example I can give is that of the chief engineer of the Lexus IS-F, Yuhiko Yaguchi. The origional prototype was built by him and a select team of car nuts after hours at toyota HQ. They used a pre-production mule IS300, a TRD 5.0 v8, stroked to 5.2 litres, bolted in a six speed manual, Torsen in the rear, and then bilstiens all round. That's the car that convinced the board to have a go. He still has it and still drives it, it makes around 320KW, and a stump pulling 650NM. I'd be partial to an E46 M3 with the S62 V8 out of the E39 m5 in the front. I think that would be great fun.