rx8wannahave

LOL...yeah, I remember that story also...I think it's fake but if it's not, WHAT A COMPLETE FOOL!!!!!

I like bikes, but too many big SUV's and bad drivers for me to take the risk. Now...if everyone drove a bike...I'd like one too.

Be safe out there Guy...

guy321

I'd let you if i thought you could ride it without dropping it.. find a buddy with a dirt bike and atleast learn how to go straight... You dont HAVE to turn 1/4 mile comes quick on a bike.

guy321

Thanks, I will! I was just joking , NEVER take your boy out on a bike duct taped!!!!!

SERIOUS!

epitrochoid

i have a pocketbike..does that count?

Senna

Does Smog Friendly technician = CARB legal??

rx8wannahave

NO WAY IN HELL would I EVER do such a thing, heck...on his baby carry thingy I keep the bar up at all times so just in case (GOD FORBID) it would act as a roll cage for the little guy...lol.

Raptor2k

.

ALXVA8

Scott, have you had the opportunity to begin tuning the full kit on a test car?

slavearm

Scott.... why don't you fly out to Cali a couple days early and bring this kit with you... I will put you up at my house, and pay for your time. Crap, I will even break out the barbeque and make the wife cook! You are coming to Cali anyways yah?

stickmantijuana

get in line dude

evilmiata

I get a kick out of this comment, since Scott got Manuel's custom GT35 setup (the one he sold to fund is 3-rotor) running on the Interceptor. I'm not saying that he's running a GT35 ('cause I don't know), but it does say a lot about his tuning abilities and the equipment he developed.

BTW, Scott: No fair dropping this bombshell when I'm out of the country!!!

Fanman

Two different setups. Manuel's first setup was his Greddy kit with the Greddy turbo. He was essentially the first one to really push his Greddy setup, including sealing up the internal wastegate & attach an external wastegate to it. On finding that the Greddy setup maxed at around 12 psi (rapidly lost efficiency) & little over 300 whp +/-, he pulled the kit and essentially went to a custom GT35R kit afterwards. After finding that wasn't enough, he pulled it & is now going with a 20B setup. Crazy Puerto Ricans & Rotaries. Gotta love em' !.

epitrochoid

This was all done on a different car, the black MS-kitted test mule

btw what did you end up putting down?

evilmiata

Dunno. I think the extra two intake ports are closed, since a NA 8 pulled on me last night. I'm going to try cracking open the intake manifold tomorrow.

ALXVA8

Hey Scott, how's it coming? I'm sure if you had something to post you would have done so, but I felt like asking anyway.

rommel

wtb more updates

MazdaManiac

iTrader: (3)

Let me see if I've got this right.

5 PSI. That is a pressure ratio of 1.34.
Stock wheel horsepower power is roughly 170 to 190. Lets say 180 for the sake of argument.
That means 300 hp is a performance increase ratio of 1.4.

So you acheived more power out than you put in?
Ladies and gentlemen, I present to you: The Perpetual Motion Machine!

You do realize this isn't actually possible, right?

Even if you acheived 100% efficiency this couldn't happen.
In a perfect world, a pressure ratio of 2 would yield double your base power. It doesn't because it isn't. A decent margin is about 77%. Really phenominal engineering will occasionally produce 85% efficiency.
But even at 100% efficiency, a pressure ratio of 1.34 would make 241 wheel horsepower. You would need a pressure ratio of 1.6 or better in a perfect world and 1.8 or better in the real world (about 11 PSI) to do this.

Without having a base run dyno for that car, you turbo dyno runs are worthless.
Worse yet, they are suspect.

I really hope 5 PSI can make 300 WHP. It would radically change my world and everything I've learned over the past decade or so.

carbonRX8

iTrader: (1)

While I agree with you that 5psi producing 300hp is...interesting, perhaps even qualifying as curious, I dont think your analysis is quite correct enough to kill the possibility. To double the power output, you would need AT LEAST double the fuel per minute and mass of air per minute. Unfortunately, there is nothing in the dimensions of PSI that even hint at the increase in flux. Sure, if you make the assumption that the flow restriction is past the tb and this restriction is 5-10x greater than any restriction prior to that, then you can use Hammond's postulate to scale kinetics with steady state values. But that may not be the case here. Also, as I understand, Scott's turbo has a larger compressor. Could that skew the numbers in his direction???

rotarygod

I originally thought the same thing last year when others were saying they were getting numbers that didn't seem right for their boost amount. This meant 2 possibilities. The first is that their numbers are wrong. The second is that the Renesis makes far more power than what we think it does and the tuning is so poor from the factory that we aren't seeing this. We now know this to be the true answer. This meant that way of thinking, which I myself also did, was wrong. How it is tuned has nothing to do with the total potential of the car. If we retuned the Renesis so that it did 210 hp naturally aspirated but changed nothin in the engine itself, it won't have any more potential when used with forced induction than it did at 180 hp. Nothing changed but the tuning.

The Renesis so far has been tuned to see about 210-212 rwhp. That is with a stock engine and some good tuning. This is realizing the engine's potential. Paul Yaw told me in a phone coversation 3 years ago that the Renesis could "easily" do 250 fwhp with just good tuning and that it was just poor tuning holding it back. It took 3 years for anyone to match this so it has been verified. Scott actually thinks the engine has a litle more left in it. The engine can do it. By judging how much it should produce based on what it dyno's at stock, we are missing a big part of the story. We aren't being told something. By basing our estimates off of these numbers, we are assuming that the engine is producing all that it can already. It isn't.

When estimating how much power we would get under boost, we need to go off of crank power and not rear wheel. We can see that the Renesis when properly tuned is a 250 fwhp engine. The 3rd gen RX-7 was rated at 255 fwhp and dyno'd between 215-220. The RX-8 drivetrain is no more inefficient than the RX-7's. Since we know a properly tuned Renesis cany get within a couple of horsepower of the 3rd gen on the dyno, we can see where it should be at the engine. 250 is a great place to start. It might even have more in it yet and we just haven't seen it. That too is a possibility so again this new number will be based on the assumption that this is all the engine has in it.

We can see that the drivetrain losses are around 35-40 hp or so. Do not go by total percentage of power made. This is very innacurate and sadly what most people go by. On top of that they estimate far too much loss which inflates what they say the engine actually produces. It takes so much power to spin the dyno regardless of what the engine produces.

Now we start with an assumption that the engine can produce a max of 250 fwhp. Again this means it can make no more. We don't know that for sure but we do know for certain that it can make 250. Scott did 300 rwhp at 5 psi. Adding 35-40 hp back in for dyno losses means that we need to be able to hit 335-340 fwhp at 5 psi. Let's see how good our knowledge of the engine really is.

You yourself said that the pressure ratio of 5 psi is 1.34. To that we can all agree. What is 1.34 X 250hp? 335 hp!!! Yes this assumes 100% efficiency which we know isn't happening since we are getting some loss. This only means that Scott is in fact correct and that the engine has a little bit more left in it than we think it does. He was speculating about 10 hp or so. A 10 hp loss through an efficient turbo system at 5 psi, I can believe that. At the very least it is close to that. Maybe a few more.

Perpetual motion? I think not. The formula is just based on a wrong assumption that the engine produces less than it can. We need to base our formulas on what the engine can do and not what it is doing. That's the big mistake. We all know tuning can change that aspect.

MadDog

Have to disagree with you there. If frictional losses were a constant, then we'd have to dyno negative HP down at the low end where the engine actually makes less than this magical 40hp, right?

Obviously, the frictional losses are not a constant. Frictional forces are proportional to velocity terms. In our case, force is in units of torque, and angular velocity is RPM.
T_friction=(some constant)*Angular Velocity

If you want to see what effect that has on HP measured, its

HP_lost_due_to_friction=T_friction*(constant)*RPM/5250

Its obvious that HP lost IS a percentage of HP made by the engine, NOT a constant.

rotarygod

Dyno losses increase with speed. If we had a 40 hp engine, it couldn't get a dyno turning very fast could it? We do know that if nothing changes but the power of the engine, this includes the rpm's we take the car up to in each run in the same gear, the dyno losses also can not change between the 2 runs. If a 200 hp engine loses 40 hp to get the dyno spinning up to a certain speed, a 400 hp engine running up to that same speed is also going to lose 40 hp to the dyno. A 40 hp engine obviously can not get the dyno moving this quickly. This is very easy to explain.

MazdaManiac

iTrader: (3)

OK, let me lay it out another way.

First, lets accept the idea that the drive line eats 35 to 40 HP. That is almost 30 kilowatts which is WAY more heat than it actually radiates, but I digress.
That means Scott is producing at least 335 HP at the crank.
This means a few things:

1) At .55 lbs of fuel per HP per hour (the BSFC of a rotary is actually higher, but I'll use a typical piston motor number for the sake of argument and to be conservative), the motor would be consuming 184 lb/hr of fuel. That is the flow rate equivalent to 1930cc, which is at the limits of the factory injectors which are about 2100cc at 100%. 85% would be 1785cc. Even with bigger P2s from the AT, you still only have a safe flow of 1972cc.

2) Assuming an A/F of 12:1, that is 6.6 lb/hr of air or 481 CFM. Even with a turbo at its peak efficiency (which will, realistically, be around 75% at the HP peak) and the motor sporting a 90% VE, you would just barely make that flow number at 9200 RPM. According to the dyno plot, this magic flow rate was hit by 7400, which is not possible at 5 PSI even if the turbo and motor both ran at 100% efficiency. The N/A flow at that RPM is 343 CFM. To hit 481 CFM would require a PR of 1.4 on a system with 100% effciency. With a VE of 85% and a comp. eff. of 75%, you would need 12+ PSI to do the same. Even if you mustered 95% out of both the motor and the turbo at precisely that RPM, you would still need 9 PSI to flow that much air through the motor at that RPM.

All of these numbers were optimized to try to get to the conclusion. Go with real world numbers for BSFC, VE, comp. eff., etc and you are a world away from the posted result.

Uh, gearing. A 40 HP motor will get the dyno spinning just as fast as a 500 HP motor, it will just take longer.

rotarygod

Remember what Richard is so fond of saying. "When the results don't match the theory get a new theory". Mine fits.

rotarygod

It will either A) run out of rpm so it will never happen, or B) not have the power to do it when geared properly to get it to that speed. Neither of these is a violation of physics. In fact they fit together with each other quite nicely. The engine just couldn't do it.

maxxdamigz

iTrader: (1)

There are 2 sources of losses: Inertial and frictional. Depending on drive train components in a system, the share between these can probably be anything.

Frictional losses depend mostly on speed. As rg stated, pretty much, an engine driving a dyno from a simulated 30 mph to a simulated 100 mph will have the same speed and, therefore, frictional losses at either end.

Inertial losses will rise with horsepower. Accelerating the drivetrain its self between 2 speeds is a power loss. A 400 hp engine will accelerate faster and dump energy into that motion faster than a 200 hp engine. This is why a dyno pull in first gear will show a greater gain from a LWFW than a 4rth gear pull.

Now, I can't really say what the balance between the 2 is in the RX-8. I have no idea. Maybe a stock engine loses 40 hp and a 400 hp one loses 50. There is a case to be made for both types of losses so I should think you are both right to a certain extent.