Charles R. Hill

iTrader: (7)

There are several other things that those most actively participating in this thread may not be interested in discussing, Paul, but you are on the right track with your hunch.

It's not that MM wasn't AWARE of other turbos, it was in consideration of a number of factors that caused him to decide on the particular 3071R he has chosen to include.

The cool thing, for BHR, is that PTP, Esmeril, and others may help me to sell driveline pieces sooner rather than later.

How weird is it that Jeff doesn't just crank up the boost and help me sell more **** to people when they break stuff? I gotta have a talk with him about that............

arghx7

On these larger wheels, the biggest issue here is boost control/wastegate plumbing (and its associated packaging problems). You will be hard pressed to find a 60-1 or 62-1 with an internal wastegate configuration. Even if you did find an internally wastegated version, I'm not sure you could trust it to control boost--unless it was a custom hybrid turbo like the 60-1 hybrid that BNR Supercars makes for 2nd gen Rx-7's.

There are T3/T4 60-1/62-1's and full T4's. The T3 is probably going to come with the stage 3 wheel (56mm exducer, close to what the 3071 has). The T4's usually come with a P trim wheel, which has a 64 mm exducer. For a T4 you would probably go with .82 or .96 A/R. For the T3, probably a .63 or .82 A/R.

I ran a T4 60-1 with a .96 A/R on my 2nd gen, but I cannot comment on what spool would be on a Renesis because I had 8.5:1 compression and porting. I will say that I saw positive pressure by maybe 2500, but it certainly nowhere near as responsive as say the stock sequential twins on an FD.

MazdaManiac

iTrader: (3)

Just remember -

I tried a BUNCH of different turbos before I picked this one.

And, by tried, I don't mean "did the math".

paulmasoner

iTrader: (1)

well, the more i try to think about it, the more the ideas slip my mind( i swear for a minute earlier i almost had a line of reasoning for saying that, now i cant even remember what i was thinking)... i may not be the best person to be actively involve in such a discussion. But i sure as hell would love to spectate till i catch up. here or elsewhere...

tdiddy

Ok, I understand all the calculations except the Boost pressure? Can you explain where you are getting this number from?

I tried calculating MAP using the formula from Garrett's website but something must be wrong.

MAP = (Airflow lb/min) x (Gas Constant) x (460 + Tin) / (VE) x (rpm/2) x (Disp)
MAP = (51.4) x (639.6) x (460+168) / (1) x (9000/2) x (80) = 57.35 – 14.7 = 42.65 psi

Now I know it doesn't take 42+psi manifold pressure to make 400bhp???

Kane

iTrader: (1)

I am not sure what you mean? That is the Boost Pressure it takes to get the Density Ratio required to meet the airflow goals.... anything less and you don't get 50 lb/min and anything more and you get more than 50 lb/min. On our motor of course.... a bigger motor would require less pressure.

paulmasoner

iTrader: (1)

sure the bold part is right? isnt there something different about a rotary as far as how displacement is calculated that you have to think about here.... the way i worked it i came up with MAP = 13.97 whih is much more realistic

Kane

iTrader: (1)

No - displacement is the same 80 cubic inches.

The multiplier for VFR is half what a piston engine is to account for being a "two stroke".

paulmasoner

iTrader: (1)

ok well the answer is the answer, who cares how you get there....


OT-this is why i never showed work in calculus.
also just found out that my wireless internet comes to a screaming stop when the microwave is on

Kane

iTrader: (1)

On Tdiddys - don't divide RPM's by two as each RPM is a powerstroke - and you'll be good.

paulmasoner

iTrader: (1)

or you could do it the REALLY hard way and break everything in the equation down to its own root equations and then it all works properly via consideration of VFR or MFR... kinda like i was stupid enough to do a few months ago


this stuff was a pain back then, im out for now, i really wanna hear more about what was said at the top of this page......

Kane

iTrader: (1)

I just wanted to have a common frame of reference to start with - and then we can argue about specific turbo's.

Obviously; front / top mount and then manifold mount are two different animals; but so far it seems like there are some turbo's that flow really well in addition to the 3071R. And to take advantage of them - you need an external WG; so it looks like packaging is an issue once again.

Brettus

iTrader: (2)

I can't do math when camel toe is staring at me ....

tdiddy

Yep, thats it! I just don't like it when someone seemingly pulls a number out of thin air like that. All numbers should have a valid explination.

Kane

iTrader: (1)

Whadda u mean? All my numbers should make sense....

auzoom

SOrry to drag it slightly off topic but for the novices trying to keep up this may help. the 101, right through to the 103 I thought were great and help explain a bit more what Kane has shown.

Andrew

paulmasoner

iTrader: (1)

thats where we were already referrencing, cept for Kane and MM who just know this stuff. The confuision was in the difference in determining the VFR/MFR for a rotary vs how you do it for a piston, which is not covered in those tech articles

auzoom

Am I right in correcting your statement to the fact you were "quoting" from it, not referencing it? While I now understand most of what is said, it was really hard to understand without the background "basics" that they go into. Talk of trims, exducers, inducers, etc.

paulmasoner

iTrader: (1)

yes and no. quoted/referrenced, i dont know which is correct as Garrett werent the ones to discover the physics of it, but the math is posted on their website. What is not on their website(AFAIK) is any mention how VFR/MFR for a rotary is different than for a piston. The way to cover down for that difference can be seen in the above posts. But for it to really make sense to simple ppl(like me) and to be mathematically complete and correct, you have to take the math given above, and break it down into how you determine each of the values that we "assumed"

And yes, the "basics" are very helpful to know, though even the "basics" can be much more in depth and complex than it let on in the tech pages - far too complex for me! I hope i understood what you were getting at

tdiddy

They make sense to me. My problem with it is that you are using an equation to calculate PR and you throw in a number like ("say 16") for one of the values when there is another equation that can be used to calculate the value.

Just arguing semantics.

MazdaManiac

iTrader: (3)

I think the original thrust of this thread has been overlooked.

Kane

iTrader: (1)

I agree - I set up the "numbers" assuming no one has a problem with the range; now all the folks who want to find a bettr turbo - go forth with numbers and bring back some efficiency graphs.

Then decide if it can be packaged in the 8 and how.

paulmasoner

iTrader: (1)

yeah when kane posted the numbers, i think a lot of us started trying to play catch-up or clearing the cobwebs...(or maybe it was just me... i need to stop posting so much and do more listening dont i)

i STILL want to see people who know better discuss the reaons why a turbo that may not look as good of a match on paper, is a better match in application, and why - why i think is the point of it(assuming im on the right track)

auzoom

I thought this set it up
We have since seen a number of compressor maps. The 2 of interest to me are the GT3071R and the GT3582R.




I agree. What I dont understand is the left side edge is you would expect surge correct? So the 3071 is right on that limit and the 3582 is well over, yet I dont get any surge and I am using the 3582.

Kane

iTrader: (1)

You don't get surge because you can't spool it up that soon.

That is the other side of the equation.... turbine maps.

I guess we can get into those here soon....