winbluerx8sport

TURBO and High-Tech Performance

(didn't buy it jsut galnced at it today at Brookshires Sept 26,04)

Fanman

I wonder what price it will be coming out at. I saw the Celica unit is MSRP $6500, street price of around $5700. That is still way too expensive if we are looking at 50 hp/50 lb.-ft. tq.

davefzr

I think Pettit's setup will be around 5300 for 50hp/50tq.... I will give any company with reliable data to back this up my 5,000 dollars for that much power.... Just who will get it first... To me... I would rather have 50hp/50tq at or around 4,000 rpm then 100 more hp... This car will be a blast on and off the track with 50 more hp and tq....

I am going to go and look for the magazine tonight.. If I find it.. I'll take a dig picture of it and post it...

shelleys_man_06

Well, these kits don't just include the blower unit. It included the whole package, such as new hoses, blower pulley(s), engine management, intake manifold, etc.. These things are costly, but they are most definitely worth it.

BTW, if you're going FI, plan on spending a lot more than what you're bargaining for.

Japan8

Problem solved with the blitz compressor or the upcoming Hymee. Either one will replace the upper intake manifold with the compressor, so no more SDAIS to worry about.

Japan8

ALSO... Greddy/Trust didn't seem to have a problem with SDAIS on their turbo setup. While Maurice has certainly done a ton of tuning work on the RX-8... the big companies have more $$ and engineers to build and test things. IF they could make it work and be reliable... then it's possible. As RG says, it's all in the tuning.

davefzr

I just called up Blitz NA and they told me that development to perfect the US kit is still being undertaken as the Japan model's ECU is different.

They gave me an estimated release date of late Fall early Winter (December).

Fanman

I understand that Blitz makes quality stuff. It is just a little (OK a lot) to swallow the price for a 50 hp gain. Once you get past $100/hp it is pretty difficult to justify. It is different if you are looking at 100hp-120hp from an SC that is $5K-$6K (like on the 350Z or S2000). The manufacturers still have to go through the same development on our cars, but 50 hp for $6K, and on top of that probably another $1K to install (if they have the front mount IC) is tough.

shelleys_man_06

Keep in mind you're initially getting 50 extra horsepower with Blitz's supercharger. If you're smart, you can tune the engine to pump out more power.

epitrochoid

i read somewhere the blitz isnt difficult to install..and why would it be?

just because it's expensive and plugs into the engine?

shelleys_man_06

Perhaps we also pay for the ease of installation?

Fanman

It doesn't look too difficult to install, not like some of the more complex turbo systems, but if they are looking to include a front mount intercooler, that will add some complexity & labor to the job. If it comes with it's own FMU, I don't know how much more than 50 hp we are going to be getting from this kit, even with tuning. In general most Screw/roots type SC's make a bit less hp than centrifugal units (though they make hp throughout the rev range vs. on the high end), so I would expect about 50 hp, maybe 60 hp. I don't see any kits currently in development where the boost is being turned up much past 6 psi. In other cars the engines start at 6 psi, but with simple SC mods you can get 8-9+ psi. I'm not sure that can happen on our engines.

rotarygod

The issue with more than about 50 hp is in the fact that the RX-8 fuel injectors can't go any higher. Even if we had larger injectors, we'd still need a larger fuel pump. There are dual pumps on the RX-8 and no return line. To add even more complexity, when you are getting gas, one pump reverses it's direction and sends fuel over to the other side of the tank. This is necessary because you gas tank sits on both sides of the transmission hump.

If you can tune it for 50hp, you can tune it for more. If you can't get any more fuel for more than this, now you've got a problem. This is why everyone is only claiming about a 50 hp gain at this point. Fix the fuel delivery issue and we'll see more.

d@id

well rotarygod has spoken , sounds good to me :>

epitrochoid

dont we have 1000cc injectors?

additional injectors are too large of a feat to control, but then there's the pumps..why not just dual walboro's? ugh $$$$$$$$$$

Ajax

So we need new injectors and 2 new fuel pumps to get an real power out of the engine? Great. We ought to redo the whole gas tank design anyway and throw away the transmission in exchange for something stronger while we're at it.

rotarygod

Nope you've got 330 cc injectors. It least I think they are 330. If I'm wrong, I'm really close. It is 3XX cc something. The standard has 6 of them and the auto has 4.

Assuming my number is correct this would only put the total at 1320 cc for the auto an 1980 cc for the standard. As a contrast, the 2nd generation RX-7 Turbo II had 4- 550 cc injectors for a total of 2200 cc and the 3rd gen RX-7 had 2- 550 cc and 2- 850 cc injectors for a total of 2800 cc. Let's go farther...

On the Turbo II RX-7, if you were to get 85% duty cycle out of the injectors you'd only get about 269 fwhp. This number is according to the Rotary Performance fuel injector calculator. You can go higher than 85% duty cycle but it is really starting to work the injectors too hard and you risk getting one stuck open. If we take and plug in 6- 330 cc injectors we arrive at a total of about 242 fwhp. If we try this same number in the 3rd gen RX-7 fuel calculator it comes out at 254 fwhp. While it may not be exact for the RX-8, it is very close. Let's average it and just say our power potential with our stock fuel injectors at 85% duty cycle is around 250 fwhp.

Most people believe the RX-8 to be around 220 fwhp or so. This means we only have about 30 hp or so more safe potential for the fuel injectors for the RX-8. Since each of the RX-7 calculators gave me different readings and the Renesis is a little more efficient, we probably have more than this. Now we are getting close to that 50 hp more power mark that both Pettit Racing and Blitz are talking about. See ths issue now?!

The problem isn't so much a tuning issue anymore as it is a fuel issue. Now you know why!

rotarygod

One of them would have to be modified to flow backwards when you are getting gas so that the other side of the gas tank fills up. It's not as easy as just swapping them out.

My solution to the whole problem would be to use a crossover tube (or 2) underneath the driveshaft that connects both sides of the tank at the bottom. This way fuel could flow across to the other side without the use of the pump. It would have to be removable in the event that the exhaust or driveshaft need to come out so some special attention would have to be made here. I don't think it would be that hard as long as AN lines were used and there was a shield around it. We could then replace each pump with new ones. I'd modify the fuel system to include a return line and use a conventional regulator. This would be alot of work but about the only way I can see that would make it possible unless someone designs a fuel pump that can duplicate the way the factory ones work.

shelleys_man_06

A problem that occured to me was the fact the RX-8, among newer cars, uses a returnless fuel system. IIRC, a returnless fuel system does not bring back heated fuel from the regulator, or something of that magnitude. This could spell a problem for big forced induction problems. I remember Paul Yaw putting together a RENESIS, and the first thing he did was convert the fuel system to a return-type. Looks like the classic Supra or Walbro fuel pump 800 cc primaries, and 1300 cc secondaries setup may not work here. I may be wrong however.

rotarygod

Yep, already said that.

davefzr

Is it too late in the day RG? You quoted yourself..

btw.. could not find that mag...

rotarygod

I quoted myself so I could show that I already mentioned the returnless fuel system. Shelley's man brought it up. I guess he didn't see it.

What mag? EDIT: Nevermind. I thought you were directing that at me. I went back and saw what you were talking about.

shelleys_man_06

Reading is not one of my strong points.

epitrochoid

is the saddle bag fuel tank common to other, more powerful cars? we could retrofit their fuel pumps in...

rotarygod

Unfortunately I haven't seen it on any other cars. Most cars use a generic fuel tank at the rear of the car somewhere. The location varies a little from car to car. Mercedes will mount it vertically between the rear seat and the trunk. Most others just tuck it away under the trunk somewhere. Mazda wanted to keep the weight distribution as much inside the wheelbase as they could. The solution to this was to put the fuel tank in front of the rear wheel centerline. It is just like the engine being placed inside the front wheel centerline. It distributes the weight better. If they hadn't done it the way they did, they would have had to use a solid tank higher in the car to clear the transmission tunnel. Obviously this is where the rear seats are so that wouldn't work from a functionality standpoint. Also, the weight would be centered higher in the car and that adversely affects handling by raising the center of gravity. The solution was to do the system that we see now. It is actually just one big tank that has a common area at the top. It just droops down on either side of the driveline. It is alot like a motorcycle gas tank that has the tunnel running through the bottom half so it can fit around the frame.

Ford has an even nicer setup for the fuel tank in the new GT. That car has the engine rear mid mounted. The gas tank is up front. They also want to keep much of the weight inside the wheelbase so their location is directly in the middle of the car. What looks like a transmission hump through the passenger compartment is actually the location of the gas tank. They didn't have to worry about a driveshaft under it though.