Brettus

iTrader: (2)

Just finished some testing to see what effect aux. port timing has on MAF/power .
Thread on it here
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/aux-port-tuning-turbo-164021/

Conclusion : Fit the blocking plate Greddy provides with the kit !

Not only will you get a broader power band (with no lean spike) but you will help prevent over-speeding the turbo and thereby decrease IATs.


The chart below illustrates this
Dark blue line : aux ports open at 6100
Pink line : Aux ports open at 4100
Light blue line : Aux ports closed and vdi inoperative. note : incomplete chart is due to this log being from an upshift from 2d gear.

05rex8

iTrader: (7)

wow...no kidding....but I don't want a 4 port, lol

gregs

iTrader: (7)

interesting i didnt use mine this time around with my install, i asked around quite a bit

Brettus

iTrader: (2)

well have 6 then and watch a 4 port clean you up

The above chart was at 9psi . For people running 6 psi the benefits will be less aparent.

05rex8

iTrader: (7)

hahahahaha

you are right though...I read that thread you linked, and I will be using my blocking plate. I just went with what MM said about it so decided not to use it. Thanks for the info Brettus.

rotarenvy

myth busting at it's best...well done brettus.

Brettus

iTrader: (2)

/\ you will have to retune for it though .
You should find that you will be running more boost pressure in the ranges above 6500 on the same boost controller settings .

05rex8

iTrader: (7)

I'm still in the process of tuning, so no big deal for me. Now I gotta track down the blocking plate in the garage somewhere.

09Factor

interesting finding Brettus, my block off plate is blocking the ACV hole on the d-pipe.
maybe I can get jeef to try this on my car at our next dyno day.

Charles R. Hill

iTrader: (7)

So are we saying that boost equals airflow?

Brettus

iTrader: (2)

/\ nope , we are saying that the Greddy does not flow enough air in its efficiency range to supply the renesis with the apv open . So to get the best out of the turbo/motor combination we need to reduce the flow capabilities of the motor to more closely match the turbo .
This will put a cieling on peak power but it's about area under the curve right ?
While it does prove that the Greddy is undersized - it can still make huge power gains over stock and give us a really nice power curve .

Brettus

iTrader: (2)

what is an ACV hole ?

mysql

let's see what happens at 12 psi with a properly sized turbo

Brettus

iTrader: (2)

/\ MM said in the other thread that he opens the APV at higher rpm than stock - draw your own conclusions from that .........

Charles R. Hill

iTrader: (7)

We all knew the kit was a compromise when it was first released anyway. I was just hoping that other readers didn't take the discussion the worng way as it mentioned boost rather than airflow and efficiency. Great effort, Brett.

Brettus

iTrader: (2)

Thanks Ray

The chart below elaborates on what we are talking about . The pink line being what I was seeing with the ports open and the blue line with the ports closed .
The blue line shows how much closer to being in the efficient part of the turbos characteristics the blocking plate will get you .
I'm running the upgraded turbo (blue map) so not sure what the stock Greddy (green map)will look like but it will be similar

zoom44

yes the greddy kit includes a band aid that should be used to cover for its deficiencies. that was covered many moons ago as Ray says.

Brettus

iTrader: (2)

well it does have its deficiencies which we all knew about but when the blocking plate idea came out many people did not use it thinkling it would reduce power as i understand .
Thought this useful to show people why they definately should use it .
BTW : Anyone who thinks a Greddy equiped car is weak sauce needs to come for a ride in mine

Charles R. Hill

iTrader: (7)

I always considered the blocking plate's main purpose to be appeasing those who evaluated turbo performance through boost pressure numbers as opposed to total airflow. That was also why I thought MM made it a priority to change the conversation about forced-induction from boost to mass-airflow.

There is some validity to what Brett has discovered but look at where the comparison happens in the efficiency island. In either case, it is clearly shown that the Mitsu turbo is too small for the Renesis. However, ya gotta give props to GReddy as they were the first mass-produced kit and it certainly served as the launch point for subsequent kits, like MM's Upgrade. Plus, it addressed the market's immediate concern; low-rpm torque.

I do have some good news regarding my personal position about turbos, supers, transmissions, and combinations thereof.

rotarygod

When you say "VDI inoperative" do you mean that it is staying closed full time?

Brettus

iTrader: (2)

well .........don't leave us hanging , what is it ?

Brettus

iTrader: (2)

yes - I think I saw an improvement with it inoperative but I need to do more runs to know for sure ....

Charles R. Hill

iTrader: (7)

That the MM Upgrade allows for some serious turbo spool-up out of the hole with a 6-speed A/T. Details forthcoming as Easy_E1 and I did an install in CA last week.

Brettus

iTrader: (2)

/\ 1/4 mile times ?

Charles R. Hill

iTrader: (7)

Perhaps in due time. If it were MY car, fershure.