Autox FD Dyno
06-02-11, 01:29 PM
#1
Autox FD Dyno
Customer from Tennessee brought up their dedicated street mod FD to have new engine management installed and set up. It's a pretty unique hotrod. Uses a turbo that I would of said was way too small to make this kind of power. It obviously works. Great responsiveness down low and the ability to move enough air up top to generate power.
It's a stock port, FD engine. Turbo is 68mm 35R hotside with the little .63 housing with a Precision 55mm billet compressor. Never would of guessed it, but the little compressor will flow enough on top end to maintain 19 psi to 8k plus. The small hotside is probably limiting top end power a bit, but the turbo is built with the sole intention of having great low rpm and transitional responsiveness; and they've achieved that. I would love to see this compressor paired with a P-trim wheel, .84 hotside, and a street ported engine. I imagine very similar responsiveness with a near 500 whp (Dynojet) capability.
It's a stock port, FD engine. Turbo is 68mm 35R hotside with the little .63 housing with a Precision 55mm billet compressor. Never would of guessed it, but the little compressor will flow enough on top end to maintain 19 psi to 8k plus. The small hotside is probably limiting top end power a bit, but the turbo is built with the sole intention of having great low rpm and transitional responsiveness; and they've achieved that. I would love to see this compressor paired with a P-trim wheel, .84 hotside, and a street ported engine. I imagine very similar responsiveness with a near 500 whp (Dynojet) capability.
06-02-11, 03:04 PM
#2
F-IT
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whats your embp? i bet that thing has enough backpressure to lift a jet!! your noit worried about hot air beiing pumped back in and causing elevated combustion temps? either way thats very impressive for such a small turbo!
06-02-11, 03:16 PM
#3
The overall shape of the curve looks like a dyno sheet from an Evo X with stock cams. This type of turbo setup and power/torque band is common on medium displacement 4 cylinders (2.0ish) that haven't been built to really rev out.
I'm sure the backpressure is far better than on the stock twins or stock FC turbo.
I'm sure the backpressure is far better than on the stock twins or stock FC turbo.
06-02-11, 05:03 PM
#4
Tenseiga
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It's a stock port, FD engine. Turbo is 68mm 35R hotside with the little .63 housing with a Precision 55mm billet compressor. Never would of guessed it, but the little compressor will flow enough on top end to maintain 19 psi to 8k plus. The small hotside is probably limiting top end power a bit, but the turbo is built with the sole intention of having great low rpm and transitional responsiveness; and they've achieved that. I would love to see this compressor paired with a P-trim wheel, .84 hotside, and a street ported engine. I imagine very similar responsiveness with a near 500 whp (Dynojet) capability.
Given the turbine maps they should flow roughly the same amount of exhaust.
I personally would go with the larger 1.06 if i went the GTX route........
The GTX3071 maxes out about 423rwhp and is a 54mm wheel and I think they are comparable to the Precisions (I don't know the trim)
I always though this would make a sweet setup (would go with the larger GTX3076 myself)...........
06-02-11, 05:25 PM
#5
Tenseiga
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This is what I was thinking woud make a fun setup.
Should flow more exhaust and have a bit more room on the compressor.
Even with the larger 58mm your hard pressed to get over 475rwhp.
Should flow more exhaust and have a bit more room on the compressor.
Even with the larger 58mm your hard pressed to get over 475rwhp.
06-02-11, 09:34 PM
#6
If you build it right, it will have bottom end torque. That's the most torque (3k and below) I've ever seen out of a 13b with a single. I also love the fact that it's a stock port engine. Lag free and very responsive for the street! This thing would be a blast to drive on a daily basis.
Edit: C. Ludwig you know at what rpm it starts making boost?
Edit: C. Ludwig you know at what rpm it starts making boost?
06-02-11, 11:10 PM
#7
If you build it right, it will have bottom end torque. That's the most torque (3k and below) I've ever seen out of a 13b with a single. I also love the fact that it's a stock port engine. Lag free and very responsive for the street! This thing would be a blast to drive on a daily basis.
As I was mentioning before, look at most of the DOHC turbo piston engines out there running stock cams and heads. The graphs usually look kinda like that.
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06-03-11, 04:59 AM
#8
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Exactly; bigger isn't always better. Most of the dyno sheets you see in this section have engines with some porting and at least a GT35R sized T3 hotside or a P trim T4. That naturally shifts the torque band to the right on a dyno sheet, which is usually better for drag racing and highway pulls but gives less low end and transient response. It's important that we don't all limit ourselves to conventional wisdom which has been around for so long on a platform this old.
As I was mentioning before, look at most of the DOHC turbo piston engines out there running stock cams and heads. The graphs usually look kinda like that.
As I was mentioning before, look at most of the DOHC turbo piston engines out there running stock cams and heads. The graphs usually look kinda like that.
This was done on a billet wheel and I'm not sure if he could have fit that much air in such a small compressor if not for these new wheels.
I think these smaller turbos if sized right (given engine mods) would work great on a rotary.
you can see with a stock port that pushes the turbo pretty hard on the 54mm.
With a SP you'd want the 58mm for sure.
06-03-11, 11:55 AM
#9
No idea what EMAP is. Would guess it's pretty outrageous. He's using a short runner (about 8-10" runners) manifold with twin Tial 38mm MVS gates. With 5 psi springs in the gate it holds 11 psi MAP. So, EMAP would need to be quite high. Keep in mind I'm not saying this is the right way to do things in all regards. There is a compromise being made in the interest of making the car perform in a certain way for a certain form of competition. Just sharing the results that were quite surprising to me.
MAP for the run in the chart was 19 psi. We integrated a trim input for boost level control and needed to setup the max boost we thought would be run and use the trim **** to back boost down to the selected level. We only saw about a 10-12 hp difference peak between 19 psi and 16 psi. That tells me the turbo is pretty much done in at this power level. I would suspect with a more freely flowing exhaust and/or porting it would struggle to maintain boost at higher revs. As-is, it holds 19 psi perfectly to 8000+. Obviously power falls off a cliff over 7000. We only a couple pulls to 8500 to verify proper fuel mixture. It's not making power up there but the car does get revved that high in competition to avoid quick up/down shifts.
Dyno numbers are true Dyno Dynamics. We've tested this same dyno back-to-back with a Dynojet with a car at pretty much the same power level and saw a 15% difference.
On the boost threshold question, the answer is we see positive pressure more or less immediately. We began the pulls at about 1500 rpm. At 1500 rpm the engine was loaded and then we went full throttle. Basically simulating idling along on the street and then matting the gas. Data log shows that it takes about 1 second from initial throttle tip till we see full throttle. Positive manifold pressure is first registered at 78% throttle at 1800 rpm. We hit 19 psi at 4000 rpm. 6 psi at 2500, 10 psi at 3000, 15 psi at 3500. Very linear response.
I've only tuned two of the Precision billet turbos and have to say both of them gave extremely impressive results. The other being a 6265 journal bearing. It really does seem that the aero of the wheels is vastly superior to the old cast wheels as they're making more power at relatively low boost levels. Not sure I believe the assertion that you need to run them at high boost levels to see a benefit over cast wheels.
The owner has ideas of building a Renesis based engine as the next step. I'm not sure I agree, but I didn't think this turbo would perform as well as it has so I'll just wait and see what the results will be.
MAP for the run in the chart was 19 psi. We integrated a trim input for boost level control and needed to setup the max boost we thought would be run and use the trim **** to back boost down to the selected level. We only saw about a 10-12 hp difference peak between 19 psi and 16 psi. That tells me the turbo is pretty much done in at this power level. I would suspect with a more freely flowing exhaust and/or porting it would struggle to maintain boost at higher revs. As-is, it holds 19 psi perfectly to 8000+. Obviously power falls off a cliff over 7000. We only a couple pulls to 8500 to verify proper fuel mixture. It's not making power up there but the car does get revved that high in competition to avoid quick up/down shifts.
Dyno numbers are true Dyno Dynamics. We've tested this same dyno back-to-back with a Dynojet with a car at pretty much the same power level and saw a 15% difference.
On the boost threshold question, the answer is we see positive pressure more or less immediately. We began the pulls at about 1500 rpm. At 1500 rpm the engine was loaded and then we went full throttle. Basically simulating idling along on the street and then matting the gas. Data log shows that it takes about 1 second from initial throttle tip till we see full throttle. Positive manifold pressure is first registered at 78% throttle at 1800 rpm. We hit 19 psi at 4000 rpm. 6 psi at 2500, 10 psi at 3000, 15 psi at 3500. Very linear response.
I've only tuned two of the Precision billet turbos and have to say both of them gave extremely impressive results. The other being a 6265 journal bearing. It really does seem that the aero of the wheels is vastly superior to the old cast wheels as they're making more power at relatively low boost levels. Not sure I believe the assertion that you need to run them at high boost levels to see a benefit over cast wheels.
The owner has ideas of building a Renesis based engine as the next step. I'm not sure I agree, but I didn't think this turbo would perform as well as it has so I'll just wait and see what the results will be.
06-03-11, 02:27 PM
#10
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No idea what EMAP is. Would guess it's pretty outrageous. He's using a short runner (about 8-10" runners) manifold with twin Tial 38mm MVS gates. With 5 psi springs in the gate it holds 11 psi MAP. So, EMAP would need to be quite high. Keep in mind I'm not saying this is the right way to do things in all regards. There is a compromise being made in the interest of making the car perform in a certain way for a certain form of competition. Just sharing the results that were quite surprising to me.
MAP for the run in the chart was 19 psi. We integrated a trim input for boost level control and needed to setup the max boost we thought would be run and use the trim **** to back boost down to the selected level. We only saw about a 10-12 hp difference peak between 19 psi and 16 psi. That tells me the turbo is pretty much done in at this power level. I would suspect with a more freely flowing exhaust and/or porting it would struggle to maintain boost at higher revs. As-is, it holds 19 psi perfectly to 8000+. Obviously power falls off a cliff over 7000. We only a couple pulls to 8500 to verify proper fuel mixture. It's not making power up there but the car does get revved that high in competition to avoid quick up/down shifts.
Dyno numbers are true Dyno Dynamics. We've tested this same dyno back-to-back with a Dynojet with a car at pretty much the same power level and saw a 15% difference.
On the boost threshold question, the answer is we see positive pressure more or less immediately. We began the pulls at about 1500 rpm. At 1500 rpm the engine was loaded and then we went full throttle. Basically simulating idling along on the street and then matting the gas. Data log shows that it takes about 1 second from initial throttle tip till we see full throttle. Positive manifold pressure is first registered at 78% throttle at 1800 rpm. We hit 19 psi at 4000 rpm. 6 psi at 2500, 10 psi at 3000, 15 psi at 3500. Very linear response.
I've only tuned two of the Precision billet turbos and have to say both of them gave extremely impressive results. The other being a 6265 journal bearing. It really does seem that the aero of the wheels is vastly superior to the old cast wheels as they're making more power at relatively low boost levels. Not sure I believe the assertion that you need to run them at high boost levels to see a benefit over cast wheels.
The owner has ideas of building a Renesis based engine as the next step. I'm not sure I agree, but I didn't think this turbo would perform as well as it has so I'll just wait and see what the results will be.
MAP for the run in the chart was 19 psi. We integrated a trim input for boost level control and needed to setup the max boost we thought would be run and use the trim **** to back boost down to the selected level. We only saw about a 10-12 hp difference peak between 19 psi and 16 psi. That tells me the turbo is pretty much done in at this power level. I would suspect with a more freely flowing exhaust and/or porting it would struggle to maintain boost at higher revs. As-is, it holds 19 psi perfectly to 8000+. Obviously power falls off a cliff over 7000. We only a couple pulls to 8500 to verify proper fuel mixture. It's not making power up there but the car does get revved that high in competition to avoid quick up/down shifts.
Dyno numbers are true Dyno Dynamics. We've tested this same dyno back-to-back with a Dynojet with a car at pretty much the same power level and saw a 15% difference.
On the boost threshold question, the answer is we see positive pressure more or less immediately. We began the pulls at about 1500 rpm. At 1500 rpm the engine was loaded and then we went full throttle. Basically simulating idling along on the street and then matting the gas. Data log shows that it takes about 1 second from initial throttle tip till we see full throttle. Positive manifold pressure is first registered at 78% throttle at 1800 rpm. We hit 19 psi at 4000 rpm. 6 psi at 2500, 10 psi at 3000, 15 psi at 3500. Very linear response.
I've only tuned two of the Precision billet turbos and have to say both of them gave extremely impressive results. The other being a 6265 journal bearing. It really does seem that the aero of the wheels is vastly superior to the old cast wheels as they're making more power at relatively low boost levels. Not sure I believe the assertion that you need to run them at high boost levels to see a benefit over cast wheels.
The owner has ideas of building a Renesis based engine as the next step. I'm not sure I agree, but I didn't think this turbo would perform as well as it has so I'll just wait and see what the results will be.
If you looked at the 54mm and 58mm wheel you can see it's well out of it's efficiency zone on the 54 and just starting on the 58.
Its just trying to keep up with the engine at that point.
It's not the same compressor map but should be in the middle between the two GT30's
You dont' need to see super high boost to see the gains in the new wheels but that is where most of it is.
You can see that even at 1bar there are gains.
the same turbo is now capable of 40-50 more hp (shifted the band to the right) BUT is able to do it more efficiently through out the usable power band. To me that last bit is what's tastey.
I think the rx8 engine is a bit over kill as a good 9.7:1 setup will be close with out the issues associated with the side ports.
For reference sake-
The Precision 55mm wheel is -
50 trim
Wheel Inducer: 55mm
Wheel Exducer: 75mm
Garrett GTX3071R
58 trim
Wheel Inducer: 54.1mm
Wheel Exducer: 71.4mm
Garrett GTX3076R -
58 trim
Wheel Inducer: 58.0mm
Wheel Exducer: 76.6mm
06-03-11, 03:04 PM
#11
That looks like an awesome powerband for where I auto-x!
Nice second gear power out of the course features and with the power fading so fast in midrange and high rpm it would be easier to modulate the throttle when you have to hold 1st through the tight stuff.
Only other single turbo I have seen with that power and powerband was a 60-1 hybrid S5 with stock exhaust wheel/housing, short tubular manifold for large wastegate and a 4" turbo back exhaust on it.
Nice second gear power out of the course features and with the power fading so fast in midrange and high rpm it would be easier to modulate the throttle when you have to hold 1st through the tight stuff.
Only other single turbo I have seen with that power and powerband was a 60-1 hybrid S5 with stock exhaust wheel/housing, short tubular manifold for large wastegate and a 4" turbo back exhaust on it.
06-04-11, 06:36 AM
#12
On a 4 cylinder (say an Evo) you'd usually take a turbo like this and wind it to 20+psi in the mid range to build torque, and then use the boost controller to intentionally let it fall off hard up top (to something like 16-17psi by 7000rpm). That seems undesireable on an Rx-7 but it is a typical strategy on other platforms.
We're used to taking a pretty big turbo with a big hotside, building it to 15-20psi more slowly and then hold mostly to the limiter. Intentionally tapering off the boost keeps the backpressure down somewhat and gives a power and torque band like the one shown here.
We're used to taking a pretty big turbo with a big hotside, building it to 15-20psi more slowly and then hold mostly to the limiter. Intentionally tapering off the boost keeps the backpressure down somewhat and gives a power and torque band like the one shown here.
06-04-11, 06:51 PM
#14
This is exactly how and why I designed my 12AT setup this way. Vtrim/s5 turbo with twin MVS 38mm and port work and 9.4:1 compression.
Interesting things to note is that on a 12A power is not falling until 7300rpm if you let boost fall from 18psi@4000rpm to 13.5psi @ 7300rpm with just a 1.0 stock s5 hot side.
I would go as far to say my 12AT has an even wider spread because its only about 300rpm later coming on but is still making meaningful numbers / rising in power at 800-1000rpm higher in the band.
In a way that is proof the .63 housing is not doing anything good.
The cheapest way to estimate EMAP is to put 1.1 - 1.4bar springs in the car and do a pull on the road and log it and see what boost you peak to in the mid/low end and then watch it decay as RPM goes up.
If its like mine you'll get a 1-2psi less than the spring around 4000rpm and then decay to something in the teens by 7000rpm.
The formula is basically 2x Spring PSI - intake pressure. That will work close enough.
Interesting things to note is that on a 12A power is not falling until 7300rpm if you let boost fall from 18psi@4000rpm to 13.5psi @ 7300rpm with just a 1.0 stock s5 hot side.
I would go as far to say my 12AT has an even wider spread because its only about 300rpm later coming on but is still making meaningful numbers / rising in power at 800-1000rpm higher in the band.
In a way that is proof the .63 housing is not doing anything good.
The cheapest way to estimate EMAP is to put 1.1 - 1.4bar springs in the car and do a pull on the road and log it and see what boost you peak to in the mid/low end and then watch it decay as RPM goes up.
If its like mine you'll get a 1-2psi less than the spring around 4000rpm and then decay to something in the teens by 7000rpm.
The formula is basically 2x Spring PSI - intake pressure. That will work close enough.
06-04-11, 09:46 PM
#15
nice setup. cool to see something different out there. almost 300 ft lbs by 3k is nice. you would need a 1.06 to reach 75-8k without dropping off. my 35r would drop off at 7700 or so. on your setup i would bet the .84 housing would barely lose any low end while giving you another 4-500 rpms to get you over 7k before dropping off. this is if you need the extra revs ofcourse.
06-05-11, 11:05 PM
#16
My thinking is-
what the dyno sheet can't really show about the powerband with these small wheels and tight hotside is the turbo response time and recovery.
You know how zingy a sequential 3rd gen feels on primary turbo with open intake/exhaust. Now, totally take away the hard to drive around 2ndary turbo transition but give it a little less power up top.
My first thought was also to be disappointed in how fast the torque dropped like a rock, but then I thought about how I am usually wishing I had more power down low and right NOW and less up top when I auto-x my (small responsive) single turbo car.
On the street or track I agree, this would drive like V-8 or turbo 6, you would get impatient always wanting to shift early to get back into the torque.
what the dyno sheet can't really show about the powerband with these small wheels and tight hotside is the turbo response time and recovery.
You know how zingy a sequential 3rd gen feels on primary turbo with open intake/exhaust. Now, totally take away the hard to drive around 2ndary turbo transition but give it a little less power up top.
My first thought was also to be disappointed in how fast the torque dropped like a rock, but then I thought about how I am usually wishing I had more power down low and right NOW and less up top when I auto-x my (small responsive) single turbo car.
On the street or track I agree, this would drive like V-8 or turbo 6, you would get impatient always wanting to shift early to get back into the torque.
06-06-11, 06:31 AM
#19
My thinking is-
what the dyno sheet can't really show about the powerband with these small wheels and tight hotside is the turbo response time and recovery.
You know how zingy a sequential 3rd gen feels on primary turbo with open intake/exhaust. Now, totally take away the hard to drive around 2ndary turbo transition but give it a little less power up top.
My first thought was also to be disappointed in how fast the torque dropped like a rock, but then I thought about how I am usually wishing I had more power down low and right NOW and less up top when I auto-x my (small responsive) single turbo car.
On the street or track I agree, this would drive like V-8 or turbo 6, you would get impatient always wanting to shift early to get back into the torque.
what the dyno sheet can't really show about the powerband with these small wheels and tight hotside is the turbo response time and recovery.
You know how zingy a sequential 3rd gen feels on primary turbo with open intake/exhaust. Now, totally take away the hard to drive around 2ndary turbo transition but give it a little less power up top.
My first thought was also to be disappointed in how fast the torque dropped like a rock, but then I thought about how I am usually wishing I had more power down low and right NOW and less up top when I auto-x my (small responsive) single turbo car.
On the street or track I agree, this would drive like V-8 or turbo 6, you would get impatient always wanting to shift early to get back into the torque.
Hate to race dynos, but 360 peak on this DD would net us 410+ on a Dynojet. I've done back-to-back testing on this dyno and a local Dynojet with the same car on back to back days. The DD rear right at 15% lower across the board. 350 peak DD v. 404 peak Dynojet.
All that said, there aren't too many stock or modded twin sets making over 400 Dynojet. And the ones that are, that I've seen dyno charts for do not have the low end responsiveness of this turbo.
06-06-11, 12:26 PM
#20
All that said, there aren't too many stock or modded twin sets making over 400 Dynojet. And the ones that are, that I've seen dyno charts for do not have the low end responsiveness of this turbo.
I agree with you 100%, when I said "more up top" I was thinking of that very small specialized subset of all out sequential twin FDs on race gas that compete in ASP or SSM auto-x. IE, a direct comparison to what this set up is for.
They alter the primary turbo control for full boost to have the same low end as this set up and carry the torque into the very high rpm with the 2ndary turbo for a broader range than this set up and have been making 400RWHP+ for maybe a decade. The secondary turbo transition is their weak point as it is hard to drive around.
I agree with you 100%, when I said "more up top" I was thinking of that very small specialized subset of all out sequential twin FDs on race gas that compete in ASP or SSM auto-x. IE, a direct comparison to what this set up is for.
They alter the primary turbo control for full boost to have the same low end as this set up and carry the torque into the very high rpm with the 2ndary turbo for a broader range than this set up and have been making 400RWHP+ for maybe a decade. The secondary turbo transition is their weak point as it is hard to drive around.
06-07-11, 03:28 AM
#21
Hate to race dynos, but 360 peak on this DD would net us 410+ on a Dynojet. I've done back-to-back testing on this dyno and a local Dynojet with the same car on back to back days. The DD rear right at 15% lower across the board. 350 peak DD v. 404 peak Dynojet.
All that said, there aren't too many stock or modded twin sets making over 400 Dynojet. And the ones that are, that I've seen dyno charts for do not have the low end responsiveness of this turbo.
All that said, there aren't too many stock or modded twin sets making over 400 Dynojet. And the ones that are, that I've seen dyno charts for do not have the low end responsiveness of this turbo.
06-09-11, 10:18 PM
#22
Rotary Enthusiast
i talked to this guy at a local event.
back pressure? 3.5in DP to 4 in exhaust should not have alot of back pressure! lol
this thing spools instant.... like spinning big 335 slicks at 3k rpm. its a monster.
back pressure? 3.5in DP to 4 in exhaust should not have alot of back pressure! lol
this thing spools instant.... like spinning big 335 slicks at 3k rpm. its a monster.
09-03-11, 11:45 AM
#23
Update:
This car just finished 3rd overall at the ProSolo Nationals. Also placed 8th overall at the Solo Nationals. It rained on day one of the Solo race and they had no rain setup and a terrible time as a result. On day two, in dry conditions, they posted the fastest time in class.
This car just finished 3rd overall at the ProSolo Nationals. Also placed 8th overall at the Solo Nationals. It rained on day one of the Solo race and they had no rain setup and a terrible time as a result. On day two, in dry conditions, they posted the fastest time in class.
09-06-11, 04:25 PM
#24
Junior Member
New guy here. I have been professionally road racing the RX-8 Renesis and have owned over a dozen of these guys and blown every one. They stink. I can share semi-off the record that we've dabbled inside the engine and these side exhaust ports are a huge limiting factor. The nature of the exhaust over the side seal area weakens the side seal spring very, very, very quickly. We have run various dramatically different tunes, Lambda values tracking about everything you can track (N.A.) and the the weak link continues to be the side seal springs. In fact, I've dumped out Renesis program in favor on the REW which is why I joined this forum. Have your customer contact me if he would like any data, spare housings, etc.
