I still think everyone is missing your point.

hp/l IS a valid argument from a physics stand point. Is it how the public looks at hp, no, but it is a valid argument when it comes to reliability and how much stress an engine will take. A 400hp LS1 is not near as stressed as a rotory, 2.0l I-4, 3.0l v-6 etc. So an equally powerd LS1 is more reliable. All CW is saying is, would a 877whp LS1 be as or more reliable than a 400hp rotary?? It's not how much power you can make or is a rotary better than an LS1. You could use a 5.0 ford or a 5.9 chrysler in the same argument, he's not attacking LS1s, they are just the typical swap.

technically that was only in qualifying trim. They tuned them back to a much more conservative number for the races...still ultimately impressive though.

I think that the LS1 FD makes great sense as a street car. You can get in, turn the key and not even think about it.

In my opinion though the LSx is not a good choice for a track car. While you don't gain much weight (compared to a similarly equipped 13b i.e. a/c and p/s) the weight is carried farther forward and higher in the vehicle. You also have to work around bump steer issues from moving the steering rack. There are absolutely work arounds for this and plenty of people tracking LS1 FDs, but I would compare those efforts to the same as having a turbo rotary street car....concessions need to be made.

^Yeah, thats is good to know that was just qualifying trim. The thing is, did they use the same motor for the race? If so, thats still more impressive than top fuel cars that get one burnout and pass per rebuild :(

Top Fuel engines are also over 8,000HP. That's 16HP/CI (a 1,440HP 13B then...). They also run on liquid T-N-T. Most cars keep the same short block the entire race and only replace gaskets/bearings (due to MASSIVE amounts of pressure/stress). Each piston/cylinder makes over 1,000HP on it's own. Think about it...

As for the "original" argument...

First, let me say that I'm a car/engine lover. I have a 13B, a 302 Ford, a 2.3T Ford, and a 401 AMC in the garage on stands, and drive a 12A, a 4.6L SOHC Ford, and a 3800 Series II GM V6. For those of you counting, that means I have at least one rotary, 4-cylinder, V-6, V-8, and at least one OHC and pushrod, and 3 carburetors and 4 types of fuel injection along with some turbochargers for good measure.

OK, so now that you see that I am truley un-biased, let me lay down some facts. As a 3-year member of the Clevite Engine Builder's Guild, I can professionally say that HP/L is bunk (notice I used HP/CI in the Top Fuel statement). The CI-to-Liters conversion is not regulated and so you end up with "off" numbers (5.0L Ford 302CI is really 4.9L, 4.9L Chevy is 305CI, etc, etc, hell 5.7L LS1 is 346CI and the 5.7L SBC is 350CI). That reason alone is enough for all professional engine rebuilders to not use HP/L.

Now, even HP/CI is looked "down" on. "Specific" output (more importantly, area under the curve) is what it's all about. Sure a 400HP 13B might be more reliable then a 840HP LS1 (honestly it's probably dead even, say it's more reliable then a 840HP 351W Ford) but the 840HP V8 would still kick the 400HP 13B's ass all over any track.

HP/engine weight (and overall car weight) is REALLY what matters in the real world. Why do you think LS1's are so popular? Huge power in a compact, lightweight (all-aluminum) design. A fully-dressed LSx motor weighs LESS then my 2.3T Turbo-4!! It takes a miracle and a half to make 400HP with a 2.3T and for saving a few hundred pounds I can have a stock LS1 with headers and a tune make 400HP all day long and be reliable as a rock.

The big point is there's different engines for different situations and different drivers. I would love to have an LS1 FD just as much as a 13B one. If you stuck both in front of me and told me to pick one, I wouldn't be able to do it. BUT, if you said I had to drag race the car I chose in my points series, I'd take the LS1 car. If you told me I had to autocross the car though, 13B. HPDE, flip a coin.

Argue back and forth all you want, but please don't ever mention HP/L again. Or even HP/CI. HP/$ is a far better standard!!

^ Was referring to the 1500HP 1.5l F1 engines :D not 13Bs.

Same difference either way. Total bunk argument from an engineering standpoint, period.

I know, but boys will be boys. There are going to be 13B nutswingers and LSx nutswingers. As far as the F1 vs. Top Fuel, the F1 is much more impressive in my book since it has to have more longevity than a one-pass Top Fuel engine.

So what about the 5-second Top Alcohol engine? "Only" 5,000HP on Alky (instead of nitro) and they go the whole race (3-4 qualifying passes, then 4+ elimination runs). Or what about Super Stock? 1,000+ HP N/A V8's going an entire season without a rebuild (24-25 races at 8-12 passes each). You're still not seeing that the ENTIRE F1 engine made the same HP in race trim as ONE piston in a Top Fuel motor!

Look, I love F1 (a LOT), but it's apples-to-grapefruit here. Engines are soooo hard to "compare" to each other, and when you hit race-specific engines it gets even more so.

That's why a 400HP boosted 13B and a 400HP N/A LSx mean so little to one another. Throw that same turbo on the LS and tell me what happens. 600+ HP is what, with no loss in drivability.

You guys should be proud though. The LSx is pretty much the only sane swap for a 13B. Any other V8 is going to be way too heavy, and way too underpowered. Sure you still see SBC's and SBF's into FB's, but they become drag cars only. Even a stock 12A can run rings around those swaps on an autocross course! The LSx is still the world's most advanced V8 engine. It didn't hit the streets until 97 (Corvette, 98 for the f-bodies) and the basic 13B was available when, 84? So it took 15 years for the V8's to "catch up" on a HP/$ and HP/weight setup.

There are the BMW and Merc V8's out there that blow the LS9's out of the water........but then HP/$ goes way down. I'm not sure about the weight either.

Don't forget the LSx has the 3rd largest V8 aftermarket on the planet behind it. Sure there's some $100K+ cars with V8's that beat an LS on HP (not on torque though!) but the LSx is available to the everyday "common man", and being that it's not tuned to the edge straight off the showroom floor, more power is a phone call away!

Assessing the shortcomings of the 13bREW's stock cooling system and IC isn't exactly 'news'.
Comparisons per liter of displacement? Comparisons per pound of engine weight? Torque comparisons? Fuel efficiency? Engine longevity/reliability?
Defending the 13bREW on an objective basis is difficult, that's why advertising agencies come up with catchy phrases like "Fahrvergnugen" (VW) and "It just feels right" or "Zoom Zoom" for Mazda. In the end, owning a rotary, particularly a FD is not unlike Homer Simpson repeatedly touching the stove to see if it's still hot. Doh!

In my opinion it is a matter of personal preference. Both engines have upsides and downsides. Those that don't think you can stick a decent turbo in an LS1 FD should see my friend Joe's twin turbo ls1 fd that dynos nearly 600 rwhp on pump gas.

P71 is soo on point in this thread.