risky business

post a dyno chart please. i would like to see you power curve now... im tired and im confused as to what all of this means

Brettus

iTrader: (2)

It is generally accepted around here that mass air flow has a corelation to hp . IE the more MAF you have the more hp you are making . It has been said the MAF figure roughly equates to flywheel hp .

Sorry I don't have a dyno with this exact setup . I can tell you that in 2nd gear my tyres are on the verge of losing traction from 3500 rpm right through to 7500rpm after which the power does taper off a little . I have had to turn down the boost in a few spots to prevent wheelspin.

Using the blocking plate will limit your peak power(if you are pushing things to the limit) a little but the gains from 6200 to 7500 far outweigh this .

Kane

iTrader: (1)

Way to take the easy way out.... LOL

Airflow is power; unless your ignition is fubar-ed / way overrich tune.

The issue like I said before is to determine when the long narrow runners become a restriction; and then open your APV, SSV or VDI accordingly.

MazdaManiac

iTrader: (3)

I played around with the APV closed this weekend.
I saw a serious drop in mass airflow - around 40 g/sec or so.
Of course, I'm moving over 400 g/sec through there normally, so YMMV.
I am opening them a little later - 6500 RPM - but I am still testing.
The VDI is held closed at all times.

Brett - you should take your runs all the way out to at least 8700 RPM.
I held mine around the rev limit for quite a while over the weekend. There is still some power from 8900 - 9200, but not as useful as at ~ 8500 or so.

Brettus

iTrader: (2)

/\ did that this afternoon on the way back from the beach .

More interesting findings
Boost at turbo at 7500 was up around 12.5 psi while remaining at 9.5 in the uim . Decided that was a little risky for my couplings so dialed it back to about 11
MAF above 7500 stays fairly steady at around 280 g/s - can feel a definate dropoff in power above 8000 but i'm ok with that as i'm normally shifting below that anyway

This is about getting the best from the Greddy - i know there is more power above 7500 but the greddy has to go so far outside its curve to get it I don't think it is the right way to go ,,,

Kane

iTrader: (1)

Was that with the APV closed all the time?

Seems like you might have found the restriction point? Unless you IAT's are super high pre-intercooler.

Brettus

iTrader: (2)

Ok here is a run I did (2nd 3rd & 4th) where I revved it right out to 8400 in 3rd . Note the dropoff in maf after about 7600 rpm (bit more than I mentioned above). This is not a concern for me because my normal shifting is at this point . I only did this run to see what was happening . Couple of things i note from this

* dropoff in 2nd gear is due to wheelspin
*note how flat the maf line stays in 4th gear - reaching 293g/s by 6700rpm

Brettus

iTrader: (2)

yes seems to be around 7000 - MM's opening at around 6500 seems pretty spot on to coincide with that ...

My IATs went up 2deg c from the start of the run through to wrung out in 4th gear ...

also worth noting is that i was very rich above 7500 - have noticed MAF does change whith air fuel ratio changes so I'm picking i could get most of that dropoff above 8000 back to around 280g/s with more tuning .

swoope

iTrader: (5)

wow,

this is good reading..


beers

Brettus

iTrader: (2)

Thought it would be worth posting this dyno from the recent socal dyno day . these are greddy turbos - guess which one has the blocking plate in .........

mysql

what boost levels? cause I made more power than all of them without the blocking plate.

Brettus

iTrader: (2)

6-7 psi as I understand but can't be 100 % on that .

Brettus

iTrader: (2)

The idea of the blocking plate is not so much about getting the highest peak power . It does give you a broader powerband and gets intake temps down by being closer to the turbo efficiency island . You also don't get the lean spike with the aux. port opening .
well worth doing in my opinion

mysql

the correct answer is to not use the greddy turbo. the blocking plate is a bandaid solution at best, but I consider it a horrible hack.

Brettus

iTrader: (2)

Fair enough . But plenty of people will be happy with the power levels the Greddy provides .
If only the turbo could last a reasonable time.

My car is somewhere in the 280-290 hp range (possibly more) and i certainly could not want for more - but that is just me .....

olddragger

iTrader: (3)

i agree. It is not about peak power--its about the curve and this is some interesting stuff. you are hitting 250hp before 7K. I like that.
OD

Brettus

iTrader: (2)

/\ i'm pretty sure i'm hitting around 280hp by 6800 rpm . Really need to dyno it again .

apocolypse31

out of curiousity,what were to happen if u kept the blocking plate on and used the gt3071r..? lol

mysql

at 9 psi and without the boost controller configured yet, i was making almost 250 whp at 5,000 rpm on the 3071r. So...

https://www.rx8club.com/attachment.p...1&d=1202600071

Brettus

iTrader: (2)

It would not be pretty

Brettus

iTrader: (2)

pretty much what i'm seeing with the upgraded Greddy .......

mysql

oooookay. If you think they're anywhere near comparable, I've got a handful of journal bearings to sell you.

Brettus

iTrader: (2)

up to about 7000 the 3071 will still have an edge at the boost levels we are talking - but not so much as you seem to be implying .
At higher boost and over 7000 it is obviously far superior .

MazdaManiac

iTrader: (3)

Not a valid question.

You should be asking:

Which was at 10 PSI and which was at 7.

gregs

iTrader: (7)

konig has no block off plate with a lower boost level but still managed to to have a higher peak whp however apocolypse31's car was a able to net a higher boost level **no boost controller** with a block off plate installed with a lower peak whp but obviously much better powerband