Hymee

iTrader: (1)

What would you call it then? I can't think of anything else it would be...

Oh. I must just be strange then.

It is no argument. It is fact. I have posted videos showing instant 13/14 lbs of boost at these RPM levels immediately when transitioning from a light throttle (manifold vacuum) to full load (full throttle).

The same set of videos, and the picture posted earlier shows about 40 or 50HP improvement of the stock figure at that point (bottom of the range). Since the stock figure was only about 40 or 50HP to start with, then I call that is a massive improvement. Like 100% rather than "not very high".

Thanks. But my argument holds water. It isn't theory. I've driven both.

Cheers,
Hymee.

mysql

boost threshold



Yeah, even when cruising I'm at least 3,000 rpm. At that RPM, there is no spool time to speak of. I get boost immediately when the throttle goes down.



That's cool. As I said before, I'm a supporter of your SC - it sounds like it's setup properly. Unfortunately, I can't buy it, so it doesn't count when discussing FI options.

Rocketman1976

+1

I don't know what his SC does but no matter what it does I bet it does not make as much torque as a Turbo that is at the exact same peak HP, its just not possible with a SC. I do recognize what you are saying Hymee about the power being readily available but as mysql said above no one drives around at 2000 rpms in our cars, thats 40 mph in 6th gear. I usually have my car at 3500 rpms at the lowest for cruising, one reason why is it seems to gunk up my plugs if I don't spin the rotors more. Yours may be better than the Pettit but turbo's are just torque monsters.

MazdaManiac

iTrader: (3)

Now you are really reaching.

Who the hell drives around at 2000 RPM? I've got Pettit people asking me if I can make their kit idle at 2000 RPM.
Not a single dyno in the comparison begins at 2000 RPM.
The MM Upgrade chart is the only one that starts at 2500 and it is destroying everything else at that point, but that is because it was a load-hold start, so its a little unfair - but only at 2500 RPM.
If the people who buy your kit are driving around at 2000 RPM, I don't think this entire discussion is of much value to them anyway because they are eating peas and carrots from a blender.

A stock RX-8 is making about 60 HP at 3000 RPM. If you put 11 PSI into it it will make about 100 at that point with the GT3071. Look at the chart.
If the S/C can do the same, then you have broken even, power-wise, since the blower is drawing nearly 30 just to make that extra 40.
The turbo is only using 3 HP at that point.

You are calling boost threshold lag. Stop doing that.

staticlag

I drive around at 2K all the time.

I have the final drive swap, so most of the time im in 6th gear at 45 or so.

Honestly, the reason I went huge t70 is strictly daily driveability and gas mileage.

On city streets I just don't need instant boost going to 300rwhp. intx injects fuel based on boost. The larger turbo will help keep me out of it on the daily drive. = better gas mileage on streets. And big power where I need it, on the track. Sure the exhaust restriction of the turbo in general will eat some gas mileage, but not as bad a gently pressing down on the pedal and getting 9psi.

staticlag

I thought so! Using the dyno brake to articfically create a boost condition. Thought it looked a bit high. But it really is what the turbo setup can do!

MazdaManiac

iTrader: (3)

So how are those blended peas and carrots?

Yeah, otherwise I don't hit full boost until 3200 RPM.

rotarygod

Considering I SHIFT at 3K rpm in both my Civic and RX-7 daily driving, I can honestly say I drive at 2000 rpm all day. I also drive through the subdivision at 30 mph in 5th gear. I only have 5! Let's just say I had a positive displacement supercharger, which I don't. If I were driving this way and needed to step on the gas, boost would be instant and the car would accelerate. If it were a turbo under these same circumstances, it wouldn't even try to build boost. It would accelerate under no boost until speed got higher and boost kicked in. I know some people say to just downshift but that's the whole point of this. A positive displacement supercharger is like having a larger engine under the hood whereas a turbo is like having a smaller engine with a turbo. That's just the way it goes. Real world driving condition on the street favor a pd supercharger in my opinion. Then again not everyone drives civilized on the street so it goes back to driving habits. I can also get 20 mpg city in a rotary all day long and still keep up with traffic.

Having a supercharger kit that idles at 2000 isn't an indication that below this is unimportant. It's an indication that tuning sucks or that something else in the total design has serious flaws.

MazdaManiac

iTrader: (3)

You have a rotary powered Civic?

Its not the tuning, its the kit.

Since the blower is pulling so much power at idle and the MAF is seeing th "puffs" from the blower, it can be pretty rough below 1100 RPM.
Sine the blower is eating more power than it is adding below 2000 RPM, I think the drag crowd is just thinking there is no reason to be down there.
Normally, I put the Pettit idle at 1100.

rotarygod

A properly done supercharger system shouldn't do this. It doesn't have to. They've got issues that need to be resolved. It's not a blower issue.

rotarygod

Where did I say that? The point is that the Civic is rated at 127 hp. I can drive it under 3K rpm all day and keep up with traffic. It's final drive ratio is also 4.44:1. If you have an RX-8, under normal driving conditions you don't need to rev high at all except for the occasional stint to help with carbon buildup.

MazdaManiac

iTrader: (3)

You think?

You didn't.
But if you are driving a stock RX-8 at 2000 RPM and step on it, absolutely nothing happens.
If you are driving a turbo RX-8 at 2000 RPM and step on it, before you can even think of the word "lag" (as Hymee likes to call it), you are already at an RPM where you have full boost.
An S/C may have full boost right when you step on it, but it is still getting out of its own way, so there will not be a performance advantage at such a ridiculous breakpoint.

mysql

You should never get 9 psi lightly pushing down the throttle.

Also a boost controller will help you configure spool times. This is all adjustable. You appear to be making decisions based on misconceptions.



That was my point. Even doubling the stock whp numbers at 2,000 rpm is still worthless. Then the SC is at a disadvantage after that.

staticlag

It was just an example.

And doesn't change the fact that I don't need more power until above 6K,

and I don't need to ever go above 6K on city streets.

Even now N/A I never go above 6K on the streets, its too fast and loud for normal driving(catless).

Rocketman1976

Your civic isn't a Rotary and wouldn't perform any differently if you stayed at 1200 rpms all day for 2 years straight but we are talking about the Renesis and I don't know about you opinion but even the dealer says the car is made to rev and you don't want to cruise around at low rpm's never getting the rpms up.
A civic doesn't use oil injection in the cylinders and does not have a problem with a possible flood issue if the spark plugs get gunked up by the oil injection.

Lets not add other vehicles into the SC and Turbo conversation since they have nothing to do with whether a SC or Turbo is good for your 9200 rpm Rotary.

mysql

If our turbo choices limited us to having power only after 5,000 rpm, I think I would be all over the superchargers. I don't like having to mash the throttle to accelerate. I like to be able to push it down and get power. Not all at once, but power modulated by throttle. So the more I press, the more I get. The 3071R delivers that. It's much more smooth and has much more torque than the greddy, but with the same spool time as the smaller turbo.

Seriously, 3k - 4.5k is where my car cruises in town and on the highway. I usually do 80-90 mph in 6th on the highway. Boost is immediate, and instant. I don't need to downshift.

rotarygod

Did you not see where I said I drive my Civic AND my RX-7 the same way??? I've owned rotaries for long enough that I know how to take care of them.

staticlag

Yeah, MM turbo upgrade is a pretty nice setup. But personally it just wasn't for me. For just the reason you describe, the linear nature of the power. I don't care about getting more power on my daily drive, I just like power to be there only when I put the pedal to the metal, much like an unlimited huge shot of nitrous.

I'm the guy who spends most of his city and highway driving in 6th gear.

Rocketman1976

Your Rx-7 redlines 2000 rpms lower then the Renny? I'm not saying you don't know how to take care of them but once again we are talking about the Renesis, it has a higher rev and different characteristics then the other motors you mentioned. Ours was designed to use RPM's to make power and just ask my baby she lovs to be revved!

I bought the car because I loved the high revving motor is I wanted to cruise at 2000 rpms I would have bought a Civic or Accord.

Rootski

iTrader: (1)

I trust RG's knowledge a LOT more than any dealer's.

rotarygod

My streetported 13B revs to 9000 rpm before I cut ignition. The redline the engine has by comparison is completely irrelevant. At the end of the day, you also have nothing more than a 13B. I don't care where you cut redline off at.

I'm not saying you have to drive around all day at 2000 rpm. I am saying you don't need to drive at high rpms to get around. You don't. Normal driving habits of the average person do not involve flooring it everywhere and driving at 5K rpms. Again, I don't care what engine you have. The Renesis is a 13B and it is a 4 stroke engine. It doesn't matter. I don't drive around all day in 3rd gear and cruise at 5K just because the engine likes to rev.

You show me a "trustworthy" dealership and I'll show you one that isn't quite as dumb and lazy as the others.

SlideWayz

+1

One of the main joys of having a turbo Renesis is that it isn't boggy and doggy at part throttle/lower RPMs. Yeah, the turbo is spinning almost all the time, but what I get in return is part-throttle torque, glorious torque.

It, uh, feels like a larger, torque-ier engine...

Did I say 'torque' enough times?

Rocketman1976

My Favorite word! I didn't see it in the SC dictionary... Hmm....

mysql

That's the thing, you don't need for it to spool when you push down on the throttle. Just how soon it starts to spool is adjustable by the boost controller. If I want to stay out of boost, I can do that quite easily. But if I want to get 11 psi at 3,800, I can do that too.

rotarygod

I'm being controversial just for the fun of it today!