[Boost Junkie]

Angel and I dynoed my car with the SP74 at SpeedCraft Engineering in Jacksonville yesterday (264 cams, GReddy "3-row" FMIC, SP 72#/hr. injectors, SP fuel system, factory flywheel, stock head, intake, and bottom end). We didn't push it TOO hard boost wise. It made 710 RWHP SAE corrected (726 actual) at 29 PSI. 575 RWTQ. The HP curve didn't appear to have peaked at 6700 RPM and torque was flat from 5300 till we stopped at 6700. The turbo wants more RPM and more boost. (The engine wasn't commenting. ) It makes 500 rwhp about 250 RPM later than the T-64, which is entirely acceptable to me as a tradeoff.

It picked up the same amount of power-per-PSI when we increased from 27 PSI to 29 PSI as it did when we increased from 22 to 24 PSI. That indicates to me that it's not beginning to run out of steam at 29 PSI (and that's not surprising, as this turbo can reportedly blow 40 PSI on a 3.8 Grand National motor). Angel and I took it out on the road after we finished on the dyno and the car felt like it's in another league compared to when it was on the T-64. It just gets stronger the higher in the RPM range it goes. With the T-64 the car came on fully by about 5500 and held pretty much that force of acceleration to redline. With the 74 it's making the same exact amout of power at 5500 (600), but it piles on another 110 RW by 6700 and the curve is continuing upward at the same rate it was at 5500.

I'll try to get the graph posted in a day or so.

Steve - likes big turbos

 

[Marcus Frost]

What kind of a/f ratios were you seeing, if any?

-m

 

[Boost Junkie]

We tuned it so that as boost came on it dipped down to the mid-11s and went back up to the high 11s touching 12:1 at the upper RPM range. FWIW, EGTs in the center of the collector were about 825 C on the GReddy gauge. With the T-64 they hit 880- 900 on a pull like that.

We initially had a bit of trouble getting a lean spot out at about 5700 RPM -- wanted to jump up to 13:1 or so. We were adding fuel in that range with the SFC, but it didn't seem to change the AFR much -- sometimes even making it go leaner. Then Angel took another tact and played with the SFC settings on each side of the lean spot and it worked beautifully. I can't give him enough props. I'd have to say that most people (including myself) would probably have left scratching their heads and muttering about why the stupid SFC wouldn't adjust the AFR in the right spot, but Angel figured out how to address it. The adjustments were seemingly counter-intuitive, but it worked perfectly. There are just too many things too many of us don't understand about all these piggy-back systems and how they interact. For any of you guys in central/northern Florida who don't have extensive tuning experience on the Supra, I highly recommend getting Angel's help when it comes time to finely tune the AFR.

 

[Marcus Frost]

What octane were you running?

That's a pretty solid fuel curve and good #s. Do you figure this turbo alone could net probably close to 800rwhp with a different intake manifold, and a higher rev limiter? What exhaust manifold are you using? You are not that far off from 800.

Where did you peak hp wise? Are you planning at all on raising the rev limiter? A turbo that can blow that much is just asking for more rpms...

Sounds like a great setup, I've heard from another friend that his 74 spools only 300-400rpm slower than his former 66... pretty insane considering the difference and power capabilties between the two.

-m

 

[Boost Junkie]

I had a 107 octane blend in the tank. I'm on the RPS header.

I'm not sure what it can do, but indications are that it hasn't begun to reach it's capability at 29 PSI on the stock head and intake. The power curve is still heading upward steeply at 6700, so more RPMs should definitely mean more power on the same setup. Open up the head and intake a bit and it should really scream. I'd think 800 rw would certainly be doable, but that's speculation at this point. It picked up about 15.33 HP per PSI boost pressure increase from 22.5 PSI to 27 PSI, and then it picked up just about exactly the same 15 HP per PSI from 27 to 29. I would like to know what it'd do as-is at 35 PSI or so, but I probably won't push it that hard.

HP peaked at 6700 where I let off.

I'd like to raise the rev limiter, but like everyone else, I'm trying to hold off and see what happens with the AEM unit. If anyone has a killer deal on a G-Force with only the rev limiter raised, I'm interested.

 

[Guest]

Steve,

Why haven't you used the FJO to tune with? Is it just because you aren't using the datalogging features?

Have you compared the A/F on the dyno to the FJO?

Also, the AEM is supposed to allow accurate tuning of the A/F using the stock o2 sensor. I found that very interesting.

 

[Boost Junkie]

The dyno chart is at:

http://www.vache.org/supra/graphics/turbos/SP74_SH1.jpg

The T-64 pull (the red graphs) was at about 28 PSI, but the fuel was pretty rich from about 5500 on up (as low as 10.8:1). AFR on the T-64 pull was about the same as on the SP74 pull below 5000, so spool-up on the T-64 was pretty normal on this pull.

Steve

 

[Boost Junkie]

I had the AFR pretty well set for the lower boost dyno runs, but hadn't done any pulls at higher boost since installing the SP74. We used the wideband on the dyno to tune it at higher boost. The FJO and the dyno wideband were in agreement as best we could tell. Without the data-logging feature, it's sort of difficult to see the detailed peaks and valleys in the fuel curve if they only cover a short band of RPM. For example, if there's a lean spot from 5200-5800, it's hard to tell exactly the extent of it because you're only in that RPM range momentarily and the numbers are flashing quickly. I definitely recommend data-logging so you can go back and study the curve a little bit.

I got the data-logging capability on my FJO a couple weeks ago, but I have an old lap top computer that doesn't have a CD ROM drive and I haven't loaded the software from the FJO CD to the lap top. One of the IT guys here at work is going to do it for me this week.

I REALLY hope the AEM is more or less what they claim it will be. It would be very comforting to know that you could tune the AFR and have it stay the same. As is, I think lots of people would be VERY surprised if they knew how badly the AFR shifts around from day to day on a Supra. I would hate to think about NOT having a wideband on my car.

Steve,

Why haven't you used the FJO to tune with? Is it just because you aren't using the datalogging features?

Have you compared the A/F on the dyno to the FJO?

Also, the AEM is supposed to allow accurate tuning of the A/F using the stock o2 sensor. I found that very interesting.

 

[qualen]

Nice dyno Steve! what's up with the purple paper? lol You wouldn't happen to have your files on disk would you?

 

[Boost Junkie]

LOL Yeah, I was wondering the same thing. At least the purple paper is better than the Red ink on Red paper they used last time. Sorry, I don't have the files on disc.

 

[Guest]

good rwhp #s, but isnt the 575rwtq a little low considering you can make similar #s on a medium sized turbo? I saw Omar's t72 dyno and he had similar rwtq. This is surprising since I see Angel for instance with a t78 making around 650rwtq. I would think with a such a big turbo your rwtq would in the 6xx range. I also remember seeing some HKS2835s making more than 800rwhp but only 5XXrwtq. Whys that? anyone? I'm ready to get educated

 

[qualen]

LOL Yeah, I was wondering the same thing. At least the purple paper is better than the Red ink on Red paper they used last time. Sorry, I don't have the files on disc.

OK, next time you go back make sure you bring a floppy with you. You will have fun manipulating your graphs on top of each other using winpep or dynojet runviewer. And you get to throw away those flakey print outs they have been giving you.

 

[Grant]

good rwhp #s, but isnt the 575rwtq a little low considering you can make similar #s on a medium sized turbo? I saw Omar's t72 dyno and he had similar rwtq. This is surprising since I see Angel for instance with a t78 making around 650rwtq. I would think with a such a big turbo your rwtq would in the 6xx range. I also remember seeing some HKS2835s making more than 800rwhp but only 5XXrwtq. Whys that? anyone? I'm ready to get educated

I think a 74mm compressor likes to flow a lot more than 264s can. Once Steve builds the head, raises the rev limit and tosses in hotter cams, the HP curve should be flatter. As it is now, it doesn't even look to make much more average power than the T64.

 

[Sound Performance]

Congrats Steve! Glad you like the turbo. Looking at the graph it seems you gained about 70 RWHP from 6000 to 6700. If that holds true and you raise the rev limiter, then at 7400 it should make 780 RWHP!! Also considering that you gained 15.3 RWHP every psi of boost, raising the boost to say 33 would get you well over 800RWHP.


Now get back to the dyno and steal Angels computer!!!



Lar
SP

 

[Boost Junkie]

Grant,
The 74 makes more power and torque at RPMs above 5500 than the 64 did on my car. Below that level it's as much as 400 RPM behind the 64, which in real-world driving isn't much of an issue on a 6-speed car. The 74 makes 500 RWHP only about 325 RPM later than the 64, and makes 600 RW at the same RPM. To keep the 74 on full boil immediately after the 1-2 shift and 2-3 shift the rev limiter needs to be raised from stock. BUT, what is one going to do with 600-800 RWHP in 1st and 2nd gear on Pilot Sports? LOL After the 2-3 shift on the stock rev limiter, the 64 is working in a range from about 600-620 RWHP while the 74 is working from about 580-710. And that's on the stock rev limiter. But all that being said and even though I actually like the 74 better on my car as it sits now, I went with the 74 thinking I'd work the head and intake and raise the rev limiter in order to really realize the potential from the turbo. I still hope to do all that, but realistically I'd say that simply raising the rev limiter would be plenty.


Larry,
That's one thing I like about the 74 -- it's got a LOT more capacity than I'm currently utilizing, and even now the car is substantially faster than with the 64 the way I drive it (I'm not a stoplight-to-stoplight racer). Hey, you must have found an extra G-force ECU or two laying around when you moved the shop recently... you should toss one of those things in the mail to me as a goodwill gesture!

Steve

I think a 74mm compressor likes to flow a lot more than 264s can. Once Steve builds the head, raises the rev limit and tosses in hotter cams, the HP curve should be flatter. As it is now, it doesn't even look to make much more average power than the T64.

 

[SupraWood]

Maybe I am off here, but isn't the Greddy 3-row a little small for that turbo? I thought it good for stock twins only???

 

[Boost Junkie]

It works pretty well for SW's 9-second, 153 MPH trap speed Supra. LOL

The so-called "3-row" isn't really a 3-row IC. It's a single ~4" wide row -- not that that matters. It is a large IC with an ~ 12" x 23" x 4" core. IMO, going thicker on an already very thick core isn't going to gain much. According to supposed experts like Corky Bell of CarTech and Bell Engineering Group, the majority of cooling is done in the front 1/3 or so of an intercooler's thickness, and it diminishes significantly from there. Adding thickness doesn't help nearly as much as adding frontal area. Thicker cores cause more difficulty in getting cooling air across the core, so it's a diminishing-returns thing.

This IC drops the charge air temp from 250-350 F (depending upon boost pressure) at the compressor outlet to about 10 degrees above ambient at the throttle body (I have probes at both places). You aren't going to get a whole lot better than that out of an air-to-air IC. BTW, these meaurements were made with the T-64 -- the SP74 seems to give lower compressor discharge temps but I haven't watched them carefully.

Steve

Maybe I am off here, but isn't the Greddy 3-row a little small for that turbo? I thought it good for stock twins only???

 

[SupraWood]

Thanks for the info...I am about to buy one for a single. I think I will go with the 3-row.

Daniel

 

[Boost Junkie]

I don't think you'll regret it. BE SURE to retain as much of the plastic under-radiator tray/shroud as possible when you install the FMIC. GReddy recommends cutting some of it away, but you don't really have to, with the possible exception of a very small spot on both lower corners which you should cut to fit snugly if you cut them at all. You want the air to have no place to go other than through the IC once it gets inside the lower grill opening. Take a heat gun and soften the tray and re-shape it a little bit to fit around the bottom of the FMIC and still bolt up to the bumper cover. I used a 3/8" strip of silicone rubber as a gasket to serve as a spacer between the tray and the bumper cover, so that the tray didn't have to be re-contoured much at all. If you chop up that tray, or worse yet, remove it alltogether, you probably won't get nearly as much air through the IC at speed. Proper ducting is VERY important in getting air through a core like a radiator.

Steve

Thanks for the info...I am about to buy one for a single. I think I will go with the 3-row.

Daniel

 

[BLKMGK]

Congrats!

Could you do some 2K-3K-4K-5K tests in a gear or two and let us know peak boost? Just about the time I think I know what single turbo I desire I see a test like this making still bigger turbos sound streetable - it's killing me! Appreciate the info on the Greddy FMIC too. That's the one I've decided on and had heard it was good but seeing instrumented readings is VERY nice.

A friend is building a little gauge that will show inlet, outlet, and differential temps for me. If it works out I'll be able to see at a glance just how well my intercooler is doing. I sure wish someone out there built such a thing for a reasonable price - the only commercial one I've ever found (digital) was priced pretty high for what it was What are you using to get your temps? I had an analog gauge built that did this but it was just too big to fit anywhere and I passed it along to a friend for his race car...

Congats on the successful install, sounds like a ton of fun to drive