yes i know you have it rigged up for blow through
i was talking about maf based to more properly utalize the cobb
ill edit previous post

 

You don't seem to understand. I have it set up as a blow through MAF based system using the cobb AP. All it takes is to use a properly sized maf tube with a screen and move the vacuum lines. I cut the stock dna tube and used a reducer to connect to an AEM intake. I use the cobb ap and a base tune from jeff and it idles perfect, runs ok. Just super rich in open loop while I am waiting for my first calibration.

 

i know
im saying it would be better to make it draw through if you can fab it up.

 

That's not what you said, and why would draw through be better? The best system is the one that accuratly reads the air flow. The blow through has accurate IAT's, accurate maf readings and it's simple. Why try changing it?

 

It really comes down to the quality of the airflow at the MAF.
It is much more difficult to get the flow smooth and uniform in a blow-through configuration, especially at low flow (idle/cruise).
The velocity is much higher in a draw-through configuration which makes it easier to get it right.

 

Well draw through with the procharger wouldnt work, atleast I dont think it would, so we are going with blow through.

On your base map I have not had any idle issues. My AFR jumps around a little when cruising but I am hoping it improves after I get the first calibration back.

 

Received my first calibration from MM about a month ago. Idle and cruise AFR improved but under boost still goes very rich and miss fires above 7k RPM (super rich). Not worried about it because I will be having the car dyno tuned on August 21st by MM at the Nor Cal SF Bay area dyno day.

Installed the 12PSI pulley and the boost comes on a lot faster but power is still way down because of the extremly rich AFR.

Installed the SOHN OMP adaptor and oil reservoir this evening along with removing the air injection pump and pipe. Used the AI delete cover from racing beat.

With the increase in power I decided to upgrade the brakes.

I am running the Enkei RPF1 18X9.5 +45MM wheels, so my BBK choices were limited to the Racing Beat BBK with the Enkei Offset. For the rear I have gone with the TCE BBK. 13" Willwood rotors and relocation brackets for the stock calipers. Track pads will be Hawk DTC-60 all the way around and for the street Hawk HPS.

Prior to installing the BBK I test my 60-0MPH stopping distance. Stock is rated at 114 feet. With my much stiffer suspension, 245/40/18 rear tires 225/45/18 fronts, stainless steel lines, 1 piece slotted rotors and hawk ceramic pads I obtained an average stopping distance of 75 feet. My first stop I was light on the brake pedal and hardly activated the ABS. My stopping distance was 112 feet. On my second attempt I got more aggressive and dropped it down to 90 feet. 3rd, 4th and 5th were 70, 75 and 75 feet with full ABS activation from start to finish. My tires also warmed up which improved grip. With track tires this distance would be significantly shorter.

I will be installing the front BBK first and retesting. Afterwards I will install the rear BBK and test again. I expect very little improvement with the front BBK but some improvement with the rear. Again, stopping distance is tire traction limited but with the rear BBK my brake bias will improve so stopping distance should improve.

The stock brake bias was designed to work with the soft stock suspension. When the suspension is upgrade (higher rate springs, stiffer sturts) the nose does not dive as much and more weight is on the rear tires. Upgrading the rear brakes should be able to take advantage of the additional weight on the rear tires and subsequently decrease stopping distances.

 

Saturday 21st is the Nor cal/sf bay area dyno day and MM will be tunning my car. So I want to make some estimations on how the car will perform.

Right now I have the 12PSI pulley installed (12psi at 9K RPM). I have not ran the engine above 7K RPM because it has not been tuned for WOT and it still runs very rich under medium to heavy loads. At idle and cruise i am very happy with the drivabilty and AFR. Under WOT right now the AFR is at the stock AFR guage limit of 11.1/1 and once I get near 7K RPM it is so rich the engine starts to miss fire.

Because MAF readings are a good indicator of HP, I have watched them and at 3K RPM I am getting 80-90 GPS, at 4.5K RPM I get 140-150, at 6K RPM 240-250 and I have seen over 300 GPS around 7K RPM. The way the procharger (centrifical supercharger) works is that it has linear flow. Double the speed and you tripple the flow and pressure. When connected to an engine/system this is not 100% accurate but its fairly close. So based on what I have seen so far, I should exceed 400 GPS at 9K RPM. 3K RPM = 80-90 GPS means 6K RPM = 240-270 ( I have seen 240-250). 4.5k RPM = 140-150 means I should get 420-450 GPS at 9.5K RPM.

I have not looked at a lot of dyno plots to know what 420-450 GPS will equal, but it should be well over 350 WHP. However, because my SC does take power to operate, my WHP number will be a little less for the same GPS flow of a turbocharger.

Driving on the street I have had the davesport 100 CPI cat installed along with an additional resonator. For the dyno tunning and race track my street mid-pipe will be changed out for a racepipe.

My final estimations will be 430 GPS of flow at or near 9K RPM and 360 WHP.

 

Good luck and would love to see you lay down those numbers.

 

cant wait to see this again in person

 

I admire your optimism - good luck man .

 

Based on how a procharger works (linear) and my preliminary readings with a rich tune and a cat installed, I should get very close to my goal/estimation.

Plus Mazdatrix dynoed 300+ WHP on the 8PSI pulley.

 

/\ well I look forward to seeing those numbers and getting something to add to the highest whp chart which has been dormant for about a year ....

 

Been waiting for this day to arrive - good luck, and buy Jeff anything he asks for - hookers included

 

 

 

I had the air flow I was going for, but not the power. 297HP, 196TQ. Torque and hp cross at 175 (5250)

 

Those are a good numbers - I could live with that for sure

 

at the nor cal dyno day 8/21/10. Tuned by MM, it was on the 16th dyno run. A proper cold air intake box and ceramic coated intake tubes will bring down the IAT and help with the power. Plus due to time Jeff was not able to fine tune it to get every last bit of power. Over all the car feels great, good idle and cruise. Great throttle response and power really comes in around 6500RPM and pulls hard to 8500RPM.

Belt slipage seems to be an issue even with the coated pulley. I will be looking at a kevlar belt from gates and maybe getting a new, larger crank pulley made so I can run a larger SC pulley, less slippage but with the same or higher overall boost.

 

/\ interesting how it levelled out at 8000 - suggesting belt slippage at that point ?

 

I had just tightend the belt so I dont think that was it. Jeff admitted we could get a little more power but we were running out of time so we called it good.

I have a cold air box I need to build and I need a permenant fix for belt slippage. Once I get those worked out I will do some data logging and head back to the dyno for some remote tunning. I wold still like to see something closer to 320 and 205.

 

Since I am aware that this kind of power curve was exactly what you wanted, would you care to explain to everyone else why this was your preferred approach (unless you already articulated it and I am out-of-date with the thread)?

 

The easy and short answer:

I like the linear power curve of the NA RX8, I like the power up top and I dont really need it down low. The procharger keeps that linear power curve and just raises it while giving me a little extra low end power so i dont always need to down shift when I would before.

More detailed explanation:

From my experiance tracking my car while NA I found the power curve and acceleration to be very smooth and linear which made accelerating out of the turns extremly easy. I have a nice suspension set up with sticky tires so I could hit my apex and just floor it without worrying about any oversteer. I would aim to keep the RPM's around 4-5K RPM in the turns and by the time I finsh my turn I am near redline and ready to shift.

When I decided to go FI I wanted to keep that same linear or smooth power feeling and the procharger (a centrifical supercharger) gives me just that. When driving around on the street I have a little more low end power which is almost always enough and when I down shift or get my RPM's up near 6K RPM I am near my peak TQ and it accelerates hard to the redline.

My hope is that on the track, the car will have the same linear feel and while I may have to modulate the trottle a little more, I will still be able basicly hit my apex and floor it or maybe slowly ease into WOT. The power will come on smooth (no power oversteer), and no excessive weight transfer to the rear (can cause the car to push).

My issues with this set up will be 1-belt slippage, 2-ECT and 3-IAT.
1-I just ordered a couple gates blue racing belts (will look pretty with my blue theme and they dont stretch as much).
2- The intercooler blocks air flow so I will be going to a single race oil cooler and adding a secondary radiator in place of the right side oil cooler.
3- The air filter sits above the radiator, so I will be building a cold air intake box to pull air from the vents in my hood.

 

/\ will be interested to hear your thoughts after your first track day ...

BTW - did you get a log of your boost profile ?

 

Unfortunately, the dyno facility didn't have a boost input on their PC.

Basically, on the dyno the car puts down 2 PSI as soon as you mash it. It gradually pushes its way up to 5 or 6 PSI by 5500 RPM and then it climbs from there to 11 PSI by 8000 and stays there until the fuel cut (with a very slight drop of .5 - 1 PSI at 9200 RPM indicated).