kickerfox

I agree it's not the holy grail. I did say there are many factors involved.

Having owned both, I can tell you both bikes have advantages and disadvantages. In the woods through the curves and obstacles, I enjoy the 4-strokes torque. It wasn't a high performance 4-stroke either (DR350SE). Through the straights, I like the 2-stroke. That argument could go on forever in a forum so lets not go there. lol

I'm trying to figure out how to explain the difference of torque curves mathmatically. I'd first need to know more about the Renesis's curve. Is it safe to say an RX-8 track car would be best operated between 4000~9000rpm? 5000~9000rpm?

HiFlite999

iTrader: (2)

My understanding is just fine, thank you very much. What I said with respect to the post of your I quoted is correct. Attempting to bring in other factors doesn't make it any less correct.

<Peak horsepower is meaningless in drag or road racing.>

Another statement of yours that is completely incorrect. Is peak horsepower the entire story? No, but then I didn't claim it was, but then didn't even use the phrase "peak horsepower". You claim with that statement that the drag-racing performance of a 10 peak hp garden tractor and a 10,000 peak hp top fueler is meaningless? Utter nonsense!

The delivery of power over the time period in question is, however, the entire story. To take a mass (car) from 0 velocity to a nonzero velocity, requires the kinetic energy be increased from 0 to some value. The work done on the (ignoring thermal effects) is equal to the change in kinetic energy.

work / time = power (with no restrictions on how that work is to be accomplished)

Power is in units of hp or kW. The more power one has, the more work per unit time, and the greater velocity (KE) gained in that time.

As far as your request for dyno results go, you could search using the work "dyno" and find the 33 page sticky of dyno results. Or you could whine that no one is answering your questions.

https://www.rx8club.com/tech-garage-...ilation-77031/

kickerfox

I already looked there. I can't find a dyno graph from an engine dyno.

I understand the relationships between torque, rpm, horsepower, ect. I'm not comparing a 10hp to a 10,000 engine either. Both of the engines in question are close in power output. Can we not agree then that torque across the band is going to play a significant role?

If the torque stays the same for both engines, the v6 will have 250hp@5252rpm and the Renesis will have 158hp@5252rpm. At that particular point, the v6 has almost 60% more horsepower. How about 3000rpm? I know the v6 has at least 200lb-ft by then (probably more) which is what, ~80%? To be fair we'll say the Renesis also has 80% of it's torque (which is doesnt). 124lb-ft is 80%. Again, we see ~60% gain with the v6. So if we operate these engines at anything less that their PEAK operating points, there's much to be gained with the v6 especially through turns and winding roads. There will be less shifting and better "drivability" with the v6.

If you put both cars (v6 RX-8 vs. Renesis RX-8) on a runway and race them head to head, The v6 won't win by much. 8%? But mash the throttle from a 2000rpm roll in first gear and the v6 will lunge ahead until I run out of gear. I'll have to shift to 2nd while the RX-8 is still reving out in 1st. Even in second gear I'll still have more torque with the v6 then the RX-8's 2nd gear. Things will get closer and closer as we reach the higher gears but I'm pretty sure I'll get the holeshot. I'll bet you this beer ---->

I have no argument that that Renesis is dishing out the horsepower at 9000rpm. 1.3L per 360deg is what, 11700L worth per minute? That has me thinking now. I wonder what the 3.5L v6 is moving. 1.75L per 360deg right? That's 12250L@7000rpm. Interesting. The v6 has ~8% more horsepower. 11,700L+8%=12636. Pretty darn close. Only off by ~3%. :D

Before I get flamed again... Yes I know I'm comparing 1.75L to 1.3L but I did knock off 2000rpm for ya.

ShellDude

iTrader: (12)

Most 8s reach peak HP/Torque well before 9000 RPM. Actually you'll see power dip the closer you get to 9k.

Brettus

iTrader: (2)

Fitting a turbo and running at a mere 5psi would blow away that v6 in all rev ranges bar 2-3000rpm ... just sayin'

kickerfox

I had considered that but a rebuild plus the turbo kit would cost much more. Do you know if the guys doing FD swaps are using a reflashed RX-8 ecu?

Mawnee

Thats what I dont get. The guy says he has an SR20 sitting in his garage...yet hes looking for an engine. He supposedly has experience with that engine and it is capable of nice power. It also only weighs something like 300lbs

Slidin8

If you have to ask this, obviously you have not put any effort into learning about the engine currently inside your car

and your searching skills must be terrible

the fd swap is the easiest and cheapest engine swap you could do, and its still not that cheap

easy 400-500hp

kickerfox

I know plenty about the engine in my car. I've owned a few RX's over the years. I haven't looked into it. Just curious. I would assume they do.

I have a Suzuki H25A but that's going in the X90 but not until the 8 is completed. Great little engine by the way. There's a 12a and a BP in storage and a B6 in the basement from my Miata days. I even considered a 15" series electric motor I have for the 8 swap but I did an electric Geo Metro already. Fun project. Ever see 120kw DC blow a loose battery terminal apart? Now that was torque. No curve, just on.

olddragger

iTrader: (3)

i havent seen an engine dyno.
Wouldnt the tq curve be the same --with or without drag?

kickerfox

The curve would be. I'm trying to find a photo to overlay on the v6 graph. I don't have any software for drawing graphs or I'd try to copy it manually and shift it up to the rated crankshaft torque levels.

Mawnee

Hah, now THAT would be a cool swap. I started looking into doing an electric rx8 at one point. But my familiarity with the lsx engine would make it too obvious of a choice had I popped my renesis.

Damnit... I am not looking for another rx8...I am not looking for another rx8......

kickerfox

bzeeeeeee....eeeeeeee....eeeeeeee....eeeeeee. What could be smoother then a rotary electric motor?

Teaser pics for Mawnee.
1. My rebuilt motor.
2. A modified Sevcon controller. (I wish every performance modification was this easy)
3. A circuit I designed for EV conversions.
4. My prototype 144v500a controller.

Mawnee

Lol, I like the "*****" dial. Kinda the equivilent of the boost controller. I never left mine alone...."a little more....a little more....MOAR!"

Slidin8

kickerfox

Oh boy...another one of those. Last I checked my power company didn't turn their generators with internal combustion engines or fire boilers with gasoline. Don't get me started on enegry ignorance.

Slidin8

Don't give a ****. Don't live in the states.

kickerfox

lucky!

bose

iTrader: (5)

Many parts of the US are coal powered, that's a fossil fuel. Although I don't think we import that...yet.

kickerfox

Ever heard of sarcasm?

bose

iTrader: (5)

Nope, totally new to me. What is this sarcasm?
Not sure when dealing with you, although now I'm pretty sure your every post is though.

kickerfox

lol No not all of them. Slidin8 was attempting to dismiss the benefit of electric vehicles. The majority of electricity produced in the US doesn't come from gasoline. Hence my comment. There's also wind, hydro, solar, and nuclear plants. Coal accounts for something like 60% of our nations electricity. I saved quite a bit of money converting my Geo. It didn't go very far. I only used it for local errands. At the time my other cars were a 2nd gen RX-7 and a '95 Caprice Interceptor.

bose

iTrader: (5)

So did you put the Caprice engine in the RX7?
Have you ever had a non frankencar

kickerfox

Does a Dodge Caravan count? lol Actually I never fucked with the Caprice other then the stereo. Oh, that reminds me! I had the Caprice back in 2004 when my friend Jack bought his new RX-8. Oh that poor car. I seen it last week when he came by to drive mine and tell me what's wrong with it. His rockers were GONE. Man did that thing rust out. He said nothing was wrong with my car btw. I think there is. Anyway... I raced him in the Caprice and won. I thought I'd get my *** handed to me. I blame his driving being it was a new car and he wasn't used to it yet. To this day that's the fastest I've driven anything. 160mph. I blame my divorce.

Where were we? Oh yeh... engine swap. No news yet. Waiting to hear back from the guy with the engine.

Found this photo. Nice cutaway of the intake manifold. Looks like they were trying at least. That intake port is a pretty straight shot into the combustion chamber. That looks like the 2004 v6. I think I see the GDI injectors. I won't be using the GDI version of the engine. Judging by the location of the starter, I'll probably have plenty of room for the exhaust on the drivers side. It'll probably drop down where the 8's starter is now. Should have tunnel clearance there.




I like where this is going. This is the AR5 transmission used in the Trooper. Lower gears are very close to the RX8. That will hurt my 0-60 time though. I'd rather have a slightly higher first and second. I'll have to use 3rd to get to 60 or use a 4.1 R&P to hit 60 in second if I can manage a 7500 redline. I'll have to see if the yard has one. RX8 in red, AR5 in blue.

kickerfox

Can any of you guys help me make a graph? Or point me to some free software that can do it? I finally found some dyno figures on the 6VE1 but it's not a graph.

46.9hp 164.21lb 1500rpm
68.1hp 178.83lb 2000rpm
87.1hp 182.98lb 2500rpm
105.9hp 185.4lb 3000rpm
123.3hp 185.0lb 3500rpm
151.5hp 198.9hp 4000rpm
168.9hp 197.13lb 4500rpm
178.3hp 187.29lb 5000rpm
183.6hp 175.32lb 5500rpm

These are rwhp "before" figures taken from a Rodeo to compare the results of a supercharger kit someone is selling. I'm not interested in the supercharged numbers. I'm only interested in the figures above. They did manage 248hp@5500rpm at the wheels with the kit.

Isuzu rated the '04 at 250hp@5,600 and 246lb-ft@3000rpm. I'll bastardize some figures here and if torque at 5500 is the same as 5600 (230.71lb-ft) then 230.7lb-ft@5500=241.59hp. Compare that with the chart above and that's about a 27% drivetrain loss? Doesn't seem right. I'll use the 15% "rule" and recalculate the above numbers in attempts to find crankshaft output.

+15% added to HP. Torque recalculated.

53.94hp 188.86ft 1500rpm
78.32hp 205.67ft 2000rpm
100.17hp 210.44ft 2500rpm
121.79hp 213.21ft 3000rpm
141.80hp 212.78ft 3500rpm
174.23hp 228.76ft 4000rpm
195.39hp 228.04ft 4500rpm
205.05hp 215.38ft 5000rpm
211.14hp 201.62ft 5500rpm