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Discussion Starter · #1 · (Edited)
Guys,
I'm looking at a lower mileage car that has dyno'd 485rwhp at 18 psi on 93 octane at 12:1 A/F. It is a 6-spd with a stock long block, 3" piping all the way back, stock OBDII ECU and no longer using the MAF. Turbo has a 0.81 A/R. The turbo kit was installed fairly recently and it is of superior quality.

Does this seem low on power? Perhaps a little timing was being pulled? I've seen a wide range of power on pump gas ranging from 480 to 530 rwhp on turbos this size. Any thoughts? I'm just wondering if I need to be concerned about a compression check. Thanks.
 

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Beau I'd definately check that out for smoething being the reason of a fairly low number for a 67. Compression check, boost leak, etc. What kind of tuning was used?
 

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Discussion Starter · #5 ·
I just learned that the boost was falling off to about 17 psi at upper rpm and you can see the power actually peak at 6,000 rpm and begin falling. I have the dyno graph
 

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Boost Junkie
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My car made 482whp at 18psi through an built auto and 3800 rpm stall converter so those numbers seem low. It should put down in the 510-530whp range, at least those seem like typical numbers for a 6-speed 67 at 18psi.
 

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485 is spot on, i made 500 on the same boost level with a non dbb 67 with a .81 a/r and map ecu, but remember dyno's have different variances. Also remember the ones making 530rwhp on pump gas have AEMs with modified timing
 

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I made 485 with my .81/AR 67mm, @18psi, For stock timing, that is about right. Remember that no two dyno's will read the same amount of power and that +/- 15hp is normal. You also have to consider the temp, and humidity of when they did that dyno pull.. not to mention how many other pulls were made...

There are many little things that can cause +/- 20hp on a dyno.
 

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The need for speed
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That power is right on for the car... there are just too many variables to say it was down on power. Just do a compression check before you buy.
 

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Power level is accurate. I make 504 whp at 20 psi on pump with my 67. I would richen up the pump map some, closer to 11.3 if I owned the car though.
 

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BoostAddict4Life
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480-500 is right on the number for a 67 on a map ecu and stock fuel. as well as the tune isnt too far off and the ecu was reset you should make close to 500 all day. from day to day and dyno to dyno alot can change.

some times you get the freaks that will make 504 or something odd, but to be safe 18 psi and pump gas should be around the 480's mark
 

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At 16.5lbs of boost my 67/.81 setup did 483rwhp, so that isn't far off at all. Most definitely can not really say that car is down on power...remember timing could of been being pulled slightly too.

Hope that helps.


Take Care
 

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Ex-hardtopper
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I just had my 67mm/.68 AR 6 speed car dynoed this past weekend. Albeit it was a "hub" dyno, not a roller dyno. 18psi on stock unopened motor netted 483rwhp on pump gas and 425 lb/ft. A/F on the wideband was in the high 10s.

Off topic question here, but maybe somebody knows. Is there a major difference in numbers between a hub type dyno vs. the roller type?
 

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At 16.5lbs of boost my 67/.81 setup did 483rwhp, so that isn't far off at all. Most definitely can not really say that car is down on power...remember timing could of been being pulled slightly too.
This is the closet post so far in rationalizing the power.

Notice how he made the same power at lower boost. Could have been several factors, but I bet the stock ECU was pulling less timing. When I had the T78 and was running 17-18psi, the stock ECU pulled about 5-6 degrees timing, and that was with 30% toluene added to 93 pump. What I data logged convinced me the typical "18psi on pump" rule was way too liberal. Should be more like 15psi max for this size setup.

I bet if you run Sunoco 104 (really should go by MON) you will make more power at the same boost.

And I don't understand how an AEM could make 530rwhp on pump without the engine knocking all to hell. You obviously have to get those numbers by adding timing (over what the stock ECU would do), and more timing means greater chance of knock. If the stock ECU pulls timing at 18psi, it's getting knock, and an AEM isn't going to make the knock go away by running more timing. Quite the contrary, it's going to blow the fucking motor eventually.

I've never seen any data on the forums concerning less timing and more boost vs more boost and less timing, but of course the stock ECU will auto adjust the timing. Just remember, in order for the stock ECU to pull timing the engine will see some knock, and that's not good. Also, if the octane is way off and too much retard happens then EGTs will go up.

The stock OBD II ECU will give up to 23-24 degrees timing given no knock, so just find what octane will give these timing values at the desired maximum boost. And too much octane can hamper power output as well.

Balancing octance requirements is very tedious.
 

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The need for speed
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This is the closet post so far in rationalizing the power.

Notice how he made the same power at lower boost. Could have been several factors, but I bet the stock ECU was pulling less timing. When I had the T78 and was running 17-18psi, the stock ECU pulled about 5-6 degrees timing, and that was with 30% toluene added to 93 pump. What I data logged convinced me the typical "18psi on pump" rule was way too liberal. Should be more like 15psi max for this size setup.

I bet if you run Sunoco 104 (really should go by MON) you will make more power at the same boost.

And I don't understand how an AEM could make 530rwhp on pump without the engine knocking all to hell. You obviously have to get those numbers by adding timing (over what the stock ECU would do), and more timing means greater chance of knock. If the stock ECU pulls timing at 18psi, it's getting knock, and an AEM isn't going to make the knock go away by running more timing. Quite the contrary, it's going to blow the fucking motor eventually.

I've never seen any data on the forums concerning less timing and more boost vs more boost and less timing, but of course the stock ECU will auto adjust the timing. Just remember, in order for the stock ECU to pull timing the engine will see some knock, and that's not good. Also, if the octane is way off and too much retard happens then EGTs will go up.

The stock OBD II ECU will give up to 23-24 degrees timing given no knock, so just find what octane will give these timing values at the desired maximum boost. And too much octane can hamper power output as well.

Balancing octance requirements is very tedious.
I made 536whp on 18psi of boost w/ pump gas on my car (T67 .81 a/r and AEM). This wasn't even close to 23degrees that the stock ECU does. I thought that was actually low hp, but after seeing other results it's not. Later on the street, I was able to take down a C6 Z06 pretty easily on the same tune. Lately my cars been boosting 19psi and after pulling logs I noticed occasional knock here and there so I ended up pulling some timing for a safer tune until I get my WG fixed.

The AEM doesn't necessarily make more power than the stock ECU, it just gives one great control of the engine. The reason I went AEM was not to make more power, but to have consistent tunes. If I ever reset the stock ECU back when I had VPC/AFC, my A/Fs would fluctuate so bad I couldn't even make a pull. A/Fs would go from 11.0 to 13.0 just like that. A Toyota engineer gave us some good feedback on the forum here regarding the stock ECU. Bottom line, don't trust that the stock ECU is actually running 22 degrees of timing just because the data logger says so.
 

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I made 536whp on 18psi of boost w/ pump gas on my car (T67 .81 a/r and AEM). This wasn't even close to 23degrees that the stock ECU does. I thought that was actually low hp, but after seeing other results it's not. Later on the street, I was able to take down a C6 Z06 pretty easily on the same tune. Lately my cars been boosting 19psi and after pulling logs I noticed occasional knock here and there so I ended up pulling some timing for a safer tune until I get my WG fixed.

The AEM doesn't necessarily make more power than the stock ECU, it just gives one great control of the engine. The reason I went AEM was not to make more power, but to have consistent tunes. If I ever reset the stock ECU back when I had VPC/AFC, my A/Fs would fluctuate so bad I couldn't even make a pull. A/Fs would go from 11.0 to 13.0 just like that. A Toyota engineer gave us some good feedback on the forum here regarding the stock ECU. Bottom line, don't trust that the stock ECU is actually running 22 degrees of timing just because the data logger says so.
The stock ECU will only run 23-24 degrees if there is no knock. At peak torque with17-18psi (wastegate minimum) on the T78, the stock ECU was running around 15degrees timing, coming up only a little in the higher rpm range. And that was with 30% toluene. If you can make 536rwhp at 18psi on 15 degrees timing you have a factory freak. Lucky you :) I still have a very hard time accepting that you made that power on straight 93 without knock.

The AEM knock control is based on how accurately you set the nosie floor, and the signal processing the AEM does to recognize and reduce it. I definitely trust the stock ECU timing control over the AEM. That's the main reason I'd never consider an AEM.

My VPC/SFC combo used to drift around a full AFR point for no apparent reason as well. That's why I got rid of it. The MAP ECU holds it's tune rock solid.

Whoa!! It's the very first time after years of hearing the opposite, that someone has admitted the AEM doesn't make more power, it just gives control. In the case of timing, it's control I don't want and is better left to the stock ECU. For years I've been hearing owners and tuners say "get the AEM you'll make more power!".

I'm a Sr EE and I read the Toyota engineers posts and disagree with some of what he said. The data logger doesn't process the data in any way. All it does is extract the data from the stock ECU and present it in graphical format. And I don't care about precise numbers anyway. I care about trends. If I can put 118 in the car, run minimum boost, and get a max value, then that's my upper threshold. Anything less and the car is knocking and I need more octane. I could care less about how precise the numbers are (although I do believe them to be accurate).
 

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The need for speed
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Lucky I still have the dyno files.... Here you go.


The AEM typically makes more power from TUNING. And I completely agree with you, nothing beats the factory ECU knock control. But you ever notice the noise varies between Supras when adding wastegates, turbos, heck even different motor mounts? What if someone has noisy knock sensors, how will the stock ECU handle that? IMO it's not good to rely on your knock sensors 100%, and that's what the stock ECU does.
 

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Discussion Starter · #20 ·
For what it's worth the car had what I consider perfect compression, so that can be ruled out as a factor. Good discussion though!
 
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