kevinbtz

iTrader: (4)

I was pretty sure I maxed the turbo out at the track so I wanted to see what power it would put down. This is the same street tune that I ran at the track but with the water meth turned off. The turbo maxes out right around 7,500rpm, had some wheel spin from 5,000 to 5,700rpm. 30.5 psi, Aem Infinity 506

rx72c

iTrader: (8)

Sounds solid. What mph did you go on that tune up?

kevinbtz

iTrader: (4)

Thanks, 138 in the 1000’ and 120 in the 1/8, the weather was pretty bad though it was raining off and on so it was really humid.

Slides

Good effort

sctRota

iTrader: (2)

What's your supporting mods? That's pretty insane

Viper GTSR

Solid! ...do you think having your water/meth on would of aided your peak #'S even further?

kevinbtz

iTrader: (4)

REW Large street port with s4 t2 scalloped rotors, turblown studs, solid stock location dowels, 4x id2000 2x id1050x, custom upper intake and port matched xcessive lower, M&W pro12 for leading and AEM smart coils for trailing, AEM Infinity with beta firmware, 155 deg thermostat and as big as I could fit intercooler and radiator.

From the testing on lower boost (24 psi) with no timing changes and same targeted AFR the water meth showed a 30 hp loss (630 vs 600) however I am guessing that it just wanted more timing with the water meth and probably would have made the same.

Howard Coleman

iTrader: (6)

pretty much maxed it out at 95.4 pounds per minute at 30 psi...

the SX-E line is waay underappreciated. of course the 700 hp neighborhood is rarified air for most. putting 700 to real use requires, among other things, an uprated drivetrain.

let's visit the Islands (Tortola is my favorite but the 70% Efficiency Island is the focus here)

the little numbers are important as to avoiding knock and are really where the game is played in turbo engineering land. it is relatively easy to deliver flow.

delivering cool flow is the challenge.

Efficiency is generally recorded between .75 and .60. the higher the number the cooler the flow due to less slippage. slippage causes heat... rub your hands together and feel the heat. i record about 325 F out of my turbo around 25 psi.

let's use the .70 Efficiency Island as a "tell" as to better get to know some of the BW turbos. we are looking for width (wider is better) and placement of that width.

at 20 PSI boost

SX-E 62................................................ ....................... 29.5..... to.... 62.5 Pounds Per Minute............................................ ................ 33..... Width/ Pounds Per Minute
SX-E 66................................................ ....................... 33.........to.....72.5 .................................................. ................................... 39.5
SX-E 69................................................ ....................... 37.........to.....78 .................................................. ...................................... 41
EFR 8374.............................................. ........................32.5......to.....64....... .................................................. ............................... 31.5
EFR 9180.............................................. ........................34.........to.....68...... .................................................. ................................ 34
EFR 9280.............................................. ........................49.5......to.....72.5..... .................................................. ............................... 23
EFR 8474.............................................. ........................38.........to.....71...... .................................................. ................................ 33

at 30 PSI boost

SX-E 62................................................ .......................35..........to.....70.5.... .................................................. ................................. 35.5
SX-E 66................................................ .......................43.5.......to.....78.5..... .................................................. ................................ 35
SX-E 69................................................ .......................46.5.......to.....87....... .................................................. ................................. 40
EFR 8374.............................................. .......................35.5.......to.....70.5..... .................................................. ................................ 35
EFR 9180.............................................. .......................43.5.......to.....79....... .................................................. ................................. 35.5
EFR 9280.............................................. .......................62..........to.....84...... .................................................. .................................. 22
EFR8474........................................... ...........................48..........to.....81.. .................................................. ...................................... 33


a few items stand out to me. the SX-E 62 starting to work very well at just 29.5 PPM. such a nice turbo for many and, as all SX-Es, priced for lunch money.

the second impressive thing to me is the SX-E 69... monster width as to the efficiency island at 41 and 40.

the negative metric clearly belongs to the 9280 with only 22 and 23 PPM width.

"water meth showed a 30 hp loss (630 vs 600)"

at 700 hp you are using 95 pounds per minute of air. is you are at 10.3 AFR (i had to pick some number...) you are using 9.22 pounds of fuel per minute... 1.45 gallons gasoline per minute (5489 cc/min net into the motor).

there are 116,090 BTUs in a gallon of gas. 116,090 X 1.45 = 168,330 BTUs base fuel.

to that you were adding a mix of water /meth.

water has negative BTUs, that's why it costs power.

let's use 600 CC of 50/50 water meth.

water has negative 8087 BTUs per gallon
methanol has 57,250 BTUs per gallon

300 CC is .079 of a gallon

water... .079 X 8087 = 638 neg BTUs
methanol... .079 X 57,250 = 4522 BTUs

4522- 638 = 3884 additional BTUs to base fuel from 600 CC 50/50 water meth

3884/168,330 = 2.3% additional fuel from AI

1 / 1.023 = .98

10.3 AFR X .98 = 10.1 AFR

very nice build, fairly flat torque curve centered at 6500 just where mine centers. i imagine traction is an interesting challenge. do you have a sheet corrected to SAE?

what pump gas were you running?

rx72c

iTrader: (8)

Sounds like you'll go 145-150mph.

Well done. Nice to see a dyno sheet match the track numbers.

WLD 07

That's an awesome power curve.
Makes power early and holds strong up top.

Well done !!!

strokercharged95gt

What kind of transmission are you running in the car??? I can't imagine its a stock tranny with that much power....

kevinbtz

iTrader: (4)

Its a old Tex Racing SR1 H pattern 4 speed dogbox from a nascar, very similar to the Gforce GSR.

TeamRX8

iTrader: (2)

Very, very inspiring. Thank you for sharing.

TeamRX8

iTrader: (2)

So I’ve been studying this situation some comparing some SXE to EFR compressor maps and want to make sure my thinking is straight.

if an EFR turbo is configured with the optional SXE compressor cover, which my understanding is the SXE cover design came after the EFR cover design and this is where the improvements come from, you’d get the quicker spooling EFR turbine coupled with the corresponding SXE compressor map.

Is this correct? It seems logical, but I haven’t seen it actually stated or discussed anywhere. It may have been and I just searched the wrong terms or something.

.

TeamRX8

iTrader: (2)

Sorry, never mind on the post above. I was comparing a EFR 7670 vs S257-SXE for a different application, but not I see the EFR gets an SXE-style cover. So not the same thing between the two.

lastphaseofthis

iTrader: (8)

i have the s257, awesome turbo. wanna get an efr 7670 for primary and sxe for 2nd in a twin seq setup. but i don't need 800hp. not even 600 any time soon

TwinCharged RX7

iTrader: (14)

If you don't need 600 or 700 who, why are you pursuing a custom twin setup like that? It would be cool to see, but probably not the best way to meet your power needs.

BLUE TII

iTrader: (9)

I think that 7670 turbo sizing for sequential twins is actually a good idea even if your hp limit is above the flow level of a single 8374 and well below the combined flow capability of two 7670s.

So that would be somewhere in the 550-800hp range.

I wasnt able to send a single 7670 into surge and 7670 ran out of poop at 5,000rpm.

Sequential 7670 would be like the stock twins- able to make just over 400rwhp, but engineered for 230rwhp.

Get a good powerband with the primary turbo and then hold it with the 2ndary turbo.

Unlike boost-up stock twins at 350hp with bolt ons that I have now- wait through the maxed out too small primary turbo power till 4,500rpm when secondary comes in and boost/torque/power band finally arrives.

Course could lower sequential transition point with too small a primary turbo, but then you dont have the engine rpm capability divided in half between the two equal size turbos, so you are going to start to feel the secondary turbo fall off in the high rpm.

So, 7670 single turbo powerband driving around and more on top end when you keep your foot in it and let the secondary turbo come on line.

I picked up two used ex Indycar 7163 for eventual sequential dream after I sold my 7670 because they are so cheap, but the idea of driving around 90% of the time on a single little 63mm exhaust wheel isnt super appealing...

BLUE TII

iTrader: (9)

^^
it was "I dont need 800hp. Not even 600 anytime *soon*."

So, assuming he needs 600hp later...

TeamRX8

iTrader: (2)

Sorry if I polluted this thread. I was only comparing the differences between two turbos for a **different application**, not a twin setup, because Howard brought up some differences between the two types. Which BW lists the S257 as a 7670, but now I recognize the the SX-E compressors are a different design geared toward the heavier, but flow optimized Inconel turbine wheel. My understanding of the lighter EFR Gamma turbine wheel is that it might not have the strength to handle the more optimized flow design of the SX-E compressor design. In the case of the S257 SX-E and EFR 7670 compressor maps, the comparison differences are a bit dramatic for efficiency vs mass flow. Kind of interesting that the S252 SX-E is essentially a 7070 vs the EFR 7064 too. I wasn’t comparing them for a 2-Rotor app though ...

lastphaseofthis

iTrader: (8)

ive gotta buddy in atlanta with an old tripoint widebody FC, hes thinking turbo v8, but ive been sold on twin seq for a while. Hes got 345 width tires, 600hp maybe too little. 8 would be good, or 1100 or 1400. right now the car is a shell, im doing a sailing/eletric boat thing, hes a family man. and so it sits and weights in his spare garage.
**end derailment.

Mkhoid

To the OP,

what fuel pump and what injectors for primary and secondary?

have the same turbo and probably going the same route

TeamRX8

iTrader: (2)

I quickly rough calculated 7500cc gas, 10,500cc E85

what he has is listed in his previous thread and is close to that on E70 (10,100)

https://www.rx7club.com/single-turbo...1133866/page3/

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