SL-C powerplant possibility?

I don't know, I just don't like how they sound. They don't rev all that high and when they are peaking at 6k rpm, they all sound like they're injesting 10 penny nails. A quad cam Toyota V8 on the other hand sounds like sweet cream butter at 9000rpm, but lack of displacement is a downer. I guess my point is that this is a clever car, and it deserves a clever motor.
 
What tranny and gearing are you planning to use with that high reving (twin turbo?) 20b grenade?

G50-50 and most likely stock gears to start with to see where I'm at and what I/engine really needs.
The stock twin turbos are very small and are limited to about 400 rwhp. They just run out of breath.
Grenade? Let's hope not ;)

Also, could you share the specs of your planned motor - sepcifically, the weight, output and length?

Lightened, race clearanced rotors and balanced rotating assembly
3mm 1-piece ceramic apex seals w/ hardened & micro-polished springs
Mazdaspeed dry-sump front cover and oil passage modifications
3/4" thick billet aluminum sump plate w/ (soon to be) integrated mounts
Large street port

Right now I have a GT4202R w/ T6 turbine housing w/ 4" exhaust...for now. I may sell/upgrade it and get a billet comp wheel that flows more without the drawbacks of going to a larger wheel. Also available now are v-band stainless turbine housings that would weigh much less than the monster T6 housing that I currently have.

I may also be getting aluminum side housings and/or going with a bridgeport. Aluminum side housings will save 45 lbs. The ports are like the lift/duration of a cam without all the useless parts of the valvetrain. So a bridgeport is pretty much like like a high lift long duration cam with more overlap.

Power projections:
Streetport 750 hp on 91 octane
Bridgeport 850+ hp on 91 octane

With a nice tune, the motor as stated should last a very long time at those power levels. There are plenty of them running and they've proven themselves. Besides the apex seals, the factory e-shaft is the weak link in a 3-rotor. There is an aftermarket billet shaft available but I don't plan on running the power levels to break the stock piece.

If that much power is more than required, contrary to some "expert opinions," a 20b could be run at lower boost (making ~450 rwhp and create far less stress on the engine when compared to a 13b at the equivalent power level and with more torque.

Not decided on an ecu so far, though not cheap, Motech is always an option. Haltech has a new ecu out too for less money but I haven't looked into yet as I'm not at that stage yet.

I've looked at rotaries before, and the Power/Weight ratio looks unbeatable on paper. I just wonder why more "enthusiasts" don't run them in lightweight cars...

They do, you just don't know about them :)
That said, it is cheaper and certainly easier to put an LSx into something. The engines are a dime a dozen, reliable and simple solutions for the simpletons :D

Internal block defect - see above for illustration.
clip_image001.gif

There is no block, hence no defect...blockhead ;)

Paul, It's cost. I have about $3500, with it headed towards about $4500 total, in my 350 chevy. I expect 450Hp but fear more like 500+. A proper 450HP rotary is in the ballpark of $20K. You can build a lot of performance with $15,000 extra to spend.

If dollars are your main concern, Howard's reasoning is hard to beat even if a 450 rwhp turbo rotary could be built for WAY less than 10k...which it can.

And by the way there,s not more than 60-80 pounds difference between a 4 barrel alum head SBC and a turbo/intercooled 3 rotor if you include all of the pumbing/etc. weight.

Possibly, but there are way too many variables to make such generalizations.

HP is HP given a(n) equal weight.
It's all in the journey.

I think that the Apex Seal problem can be solved by running the car on E85, as that makes the engine run cooler due to the lower combustion temperature of the fuel. This along with the ample room for extra oil coolers should keep this engine in check while it's set inside the SL-C.
Lots of guys running E85 with great results. The apex seals are only a problem if you have other issues leading to their failure, all of which are preventable.

So, to summarize, the issues are:
1) Cost,
2) The weight savings aren't really there, and
3) There seems to be a complexity issue as well.

1. A turbo rotary could cost more and most likely would if it is going into a car like this. Depends on the resourcefulness/budget of the builder really.

2. When all is said and done, I am hoping my turbo 3-rotor will be 40+ lbs lighter than an LSx if I use the aluminum side housings. A 13b, with the same housings could be ~90 lbs. lighter.

3. The complexity would be the same for any turbocharged engine which will always be more than an n/a engine.

It seems to me, that the rotary is perfect - in a certain HP range. Once you start trying to get over 200 - 300hp (figures from rotaryAviation), the cost, weight and complexity of the Mazda rotary starts to increase.
They are refering to the n/a vs. turbo debate in airplanes and the serious lack of packaging room they have to work with. No such limitations with an SL-C. Granted, a turbo system is more complex than if it didn't exist at all :shocked2:

"Ballpark ideas" on pump gas:
13b n/a......200-350 hp
13b turbo...300-600 hp
20b n/a......300-550 hp
20b turbo....300-850 hp

Cost, (weight and complexity to a point) of any engine goes up as power levels increase.

LS3, as Fran recommended, looks like a good balance.
LSx is the best choice for any swap, in any car, hands down.

Now I better get off this forum and get some real work done :thumbsdown:
 
I don't know, I just don't like how they sound. They don't rev all that high and when they are peaking at 6k rpm, they all sound like they're injesting 10 penny nails. A quad cam Toyota V8 on the other hand sounds like sweet cream butter at 9000rpm, but lack of displacement is a downer. I guess my point is that this is a clever car, and it deserves a clever motor.
I love the way they sound, and by any objective measure they're extremely clever.
 

Brian Hamilton

I'm on the verge of touching myself inappropriatel
I think this is where Fran made a very wise decision about the SL-C. You can put just about ANYTHING you want in that thing. Lots of LS motors. Some SBC's. Any Ford Mod Motors? Any SBF's? Dunno. How about WRX engines? They'll fit! Twin Turbo Porsche Flat-6? They'll fit!! I think I remember Fran saying the Viper V10 will NOT fit. Too damn long. BUT, just about anything else will fit from what I understand.

The cool thing is, it's YOUR car, power it with what YOU want. Hell, use that Bi-Turbo V12 Mercedes making 700+ hp and give it a little extra boost. Couple extra pounds of boost and nice intercooler setup will give that baby over 800 hp. Awesome!! Get after it man!! I'd love to see it. The engine bay of the Pagani Zonda looks AMAZING, don't see why the SL-C couldn't look the same.

Order the car and go nuts man, that's what it's all about.

Laters,

Brian
 
It just seem like there's enough room for a Mercedes V12. There's enough for the V8 but that's about, I guess?
 
I was all looking into a V12 Ferrari when I started with my car. Then I found out it would be too hard to fit, they are simply too long to for the space. Of course if money is no object I'm sure RCR could do the job.

On another note -I will certainly be doing my best to test the durability of Dave's buzz bomb up the road from me with my box of nails LSx engine. Of course I better be using ear plugs anytime I'm within shouting distance of "Rotozilla" :D

There are a few of us that are looking for ways to get around the exhaust note of the LSx engine, as the big booming sound is not our favorite aspect of the engine either.
 
I really think if the idle of the LS can be kept at a human level and not rattle fillings out it would be great. Plus an 8000+ rpm rev limit would be nice. Pushrods or quadcams I don't care about, but obnoxious idle and low rev limit get me ever time.

Eric
 
I have tried a "reverse split" cam (231/225 .577/.564 lift 110 LSA), some valvetrain mods and headwork on my LS1.
Lumpy at idle but very crisp above 2500 RPM and screams at 6000. Not objectionable at all, and these few mods made 430HP @ 6000 RPM. Easily capable of 7000 RPM but falls off a bit and flattens out around 6550.
 
with regards to the idle of the LS motors, a lot of them that you see on youtube have modified cams with lots of valve overlap, i.e. tight lobe separation angles. Given the 7 liter displacement of these motors, you don't have to go nuts with a cam in order to make pretty good power. I've got a 222/230 6xx 118 cam in my motor and it makes about 580 hp at the crank. It also idles like stock, and will rev to 7K +. Peak power is about 6200 rpm, but with this thing making over 500 ft-lbs of torque, I don't think I'll need to rev the nuts off this thing in a 2000 lb car!
 
G50-50 and most likely stock gears to start with to see where I'm at and what I/engine really needs.
The stock twin turbos are very small and are limited to about 400 rwhp. They just run out of breath.
Grenade? Let's hope not ;)

[snip]

"Ballpark ideas" on pump gas:
13b n/a......200-350 hp
13b turbo...300-600 hp
20b n/a......300-550 hp
20b turbo....300-850 hp

Cost, (weight and complexity to a point) of any engine goes up as power levels increase.


LSx is the best choice for any swap, in any car, hands down.

Now I better get off this forum and get some real work done :thumbsdown:

Dave:

First of all, many thanks for the effort you expended to shine the light of knowledge to push back the darkness of ignorance. You pretty much addressed all of the mentioned rotary issues.

Based on your figures, a N/A 20b appears to be a good choice for the SLC given the output, engine weight and lack of packaging issues. The only trade off would be cost, but leaving off the turbo would minimize the costs for that setup. Then you're looking at a cost vs. weight savings trade off, and that's an individual decision.

I was asking about the tranny setup because I've heard that the Wankel delivers its torque at higher RPMs than a 4-stroke. I was curious how you were planning to address that issue and the additional issue of the Wankel's ability to deliver HP at very high revs. I didn't know that a G50 had gears suitable for the Wankel application, and that's good to hear.

Frankly, I don't know how much more than 500hp can be reasonably utilized in a 2000 - 2200 lb car. Also, the more gas a large engine burns, the more heat that needs to be disbursed (more cooling equipment = more $, time and weight), the more gas that needs to be carried (more weight), the larger the brakes & tires need to be to get the same performance (more corner weight again), etc.

It seems to me that an often overlooked edge would be gained by looking at minimizing the overall vehicle weight. For example: shaving 50 - 100 lbs off the engine configuration, saving 30 - 50 lb of unsprung weight using carbon fiber brake rotors, leaving out the AC, stereo, leather seats, etc. Could the 2200 lb (wet weight + driver) car become a <2000 lb car? Minus 10% on the weight is like getting at 10% boost on the motor - except:
1) To get the engine boost, I need to feed it with money + weight, but
2) With the weight reduction, I get handling and braking (fun).

The hard part - and I don't mean to minimize this - is that finding pounds to save very quickly becomes hard and expensive, i.e. really expensive.


Finally, Dave I believe your quantity and quality of your research deserves a reward, and I've taken it on myself to award you this ultimate adornment of the rotary minded:
 

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Here in the Orlando area, there are many 1000rwhp cars roaming the streets, and given their weight you're looking at roughly 570rwhp per ton. I feel that in street trim the SLC would have to be competative with that, and what's more (if it really wants to shine like a diamond), do it on 93 octane pump. So to be up to that bar the average SLC would need to be belting out ~685rwhp. THat takes into account most of the pedestrian cars on the street. Now take the Caparo T1. THat little monster is knocking down between 900 and 1000rwhp per ton.
 
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