Dyno Results

[Guest Cronic]

Remove the pop off valve, and plug the hole. This is more then likely your problem.

 

 

In every one of those runs you're only making about 10psi going to the engine. The POV can only let out so much boost, which is why your huge turbo is making more power at higher boost levels.

 

basicly, plug the POV hole, lower the boost, and do another run. Im surprised your car wasn't running stupid rich on the dyno, and running like crap.

[Clifton]

Your dyno sheet says uncorrected. That would also make some difference. Although it was cool out, I don't know the altitude.

[81280zxtc]

Could part of the problem be the dyno/run? What gear was this pull done in? The graph is showing MPH not RPM and it looks like 5250RPMs occured at about 74mph. If this was 3rd gear with a 3.70 and 25" tire' date=' 5250 should be more like 82mph by my calculation. Now if he is running a 3.90 it would be closer to the dyno sped and of course a 3.54 would make it worse.

 

Am I off base or is this a consideration?[/quote']

 

The dyno pull was in 3rd gear. Tire size was 245-45R16, so I'm not sure of the diameter. I don't recall what rear ratio I have either.

 

The tuner had some questions that maybe you guys could help answer:

 

1) What would / is the max RPM range for this motor?

2) What would be max boost level for this engine?

3) How much timing can it hold / run w/ 22 lbs of boost or higher?

4) Does the factory intake have enough flow to support higher than stock HP numbers, or is there an aftermarket substitute?

 

If I could get some help with these answers, he could tune it more aggressively vs conservatively.

 

Thanks in advance.

[Drax240z]

1) 6250 is a conservative rev limit. 6500 is probably more popular.

2) Depends on your fueling.

3) At full boost you should be around 20-24* total timing if possible.

4) Factory intake can support much higher than stock numbers. However, significant improvements have been made by swapping it with a better flowing one. No aftermarket ones are available at the moment as far as I know.

5) Almost all these questions have been answered before and doing a search on each will educate you much more than this response will.

[Mack]

Did you plug your pop off valve hole yet? a completely stock motor, just with the boost wicked up should be good for almost 275rwhp-ish on stock everything.

 

also, do you have a Air/fuel ratio graph yet? that'll give us a LOT of instight as to what is going on with your motor.

[81280zxtc]

Did you plug your pop off valve hole yet? a completely stock motor' date=' just with the boost wicked up should be good for almost 275rwhp-ish on stock everything.

 

also, do you have a Air/fuel ratio graph yet? that'll give us a LOT of instight as to what is going on with your motor.[/quote']

 

I'm going to remove both this weekend and make blocking plates to cap off.

 

I will try to see if I could print the a/f graph from the Haltech and post it too.

[81280zxtc]

1) 6250 is a conservative rev limit. 6500 is probably more popular.

2) Depends on your fueling.

3) At full boost you should be around 20-24* total timing if possible.

4) Factory intake can support much higher than stock numbers. However' date=' significant improvements have been made by swapping it with a better flowing one. No aftermarket ones are available at the moment as far as I know.

5) Almost all these questions have been answered before and doing a search on each will educate you much more than this response will.[/quote']

 

Thanks for the input. I had tried to search the forum for some help, but sorta came up short w/ answers.

 

I'll try the 6500 rpm as a cut off. The shop set the cut off @ 6000 to be consertative and safe. The last thing you want is to overspeed.

 

As far as fuel, I have enough w/ plenty more to go. The 12 injectors are set up for the second set of 6 to come on under boost so I feel confident that I'll have enough fuel for more boost when we re-test.

 

As far as the timing goes, I'll pass that information on to him to see where he wants to try. Right now it's set @ 22 degrees. I think I'll try a higher boost setting before trying to advance timing..just to be safe. The Haltech is set to retard timing 1 degree when coming off the gas to prevent a major catastrophe. I'll follow up with the numbers in a later post.

 

I was thinking of getting the intake extrudehoned for better flow, but am afraid it doesn't work the way I want, I'll ruin a one of a kind intake.

 

Thanks for taking the time to reply...all your help is greatly appreciated.

[81280zxtc]

OK....Capped off the factory pop off valve and re tried the dyno. Same HP results. Did a little more tuning, and raised the boost to 24 lbs, and came up with 345 HP / 320 torque. Looked at the dyno curve and noticed that boost was coming on later in the 3000 rpm range and was topping off at around 5500, which led myself and the tuner to believe that the exhaust housing on the turbo was too large in size to create boost at a lower rpm range. We will try installing a smaller a/r exhaust housing to see if we can get the car to spool sooner.

 

Will update you when finished.

[Tim240z]

That will choke the upper RPM flow? Is that what you want to do?

[Clifton]

What's the a/r and wheel in the turbine? What was you AFR? Did he use a correction on this dyno?

[Scottie-GNZ]

If the engine is not laggy, leave the exhaust housing alone. I believe the 2.5" exhaust is becoming a restriction. The engine is responding to the boost increase but not enough and the torque seems low. You can prove that by dyno'ing the car again with no changes but disconnect the exhaust from the DP. Also, the RPM and MPH makes me believe the car has a 3.90 final drive so you might try a pull in 4th if the dyno can accomodate that kind of "speed".

[81280zxtc]

I'll try to answer Tim, Clifton's, and Scottie's questions here..

 

With the smaller a/r ratio on the exhaust side of the turbo, I wanted to see if the turbo would spool sooner. I was under the impression that since the boost is coming on late I'm either running out of engine or the turbo is not sized correctly. If the numbers change for the worst, I could always put it back the way it was.

 

Clif, I don't remember what the a/r ratio on the turbo was, I purchased it almost 2 1/2 years ago and I don't have the sheet that came with it from Turbonetics. I'll have them take a look and let you know with an update. I'll also try to get the AFR #'s and post them too and see if the tuner can factor in the corrections on the dyno.

 

Scottie, I'll try your advice to see if I disconnect the exhaust at the point where the 2 meet and try to redyno. I'll also see if we could do a 4th gear pull too, which I don't see it as a problem since I've seen them done before in the shop. I thought you needed some type of backpressure with these engines to create torque? If I'm wrong, please let me know. It's hard to find a nice exhaust with out going custom and paying for it thru the nose. I would like at some point to change it out to 3" all around, but the exhaust I find ideal is the HKS dual dragger exhaust they had on the Supras at one point in time. I just love that set up, but can't seem to find it around anymore. If I come across one, I would definitely go that route.

 

Gents, thanks again for all the input. Your posts are greatly appreciated.

[yo2001]

With 112 octane, you would want to tune the car leaner than what's safe on the 93 pump gas. IF you are rich like in 11.5:1-12:1, you actually will lose HP since the fuel can't burn completely.

 

I think standard Turbonetic 60-1/t3 comes with .63 A/R and 10 blade stage III.

 

I was seeing full boost in my car with 60-1 @ 3500rpm with 11 blade 60-1. on the dyno the torque peaked little before 4K rpm where the boost was spiking.

 

Slow spool up can be caused by a small boost leak. I would check that if you haven't.

[81280zxtc]

With 112 octane' date=' you would want to tune the car leaner than what's safe on the 93 pump gas. IF you are rich like in 11.5:1-12:1, you actually will lose HP since the fuel can't burn completely.

 

I think standard Turbonetic 60-1/t3 comes with .63 A/R and 10 blade stage III.

 

I was seeing full boost in my car with 60-1 @ 3500rpm with 11 blade 60-1. on the dyno the torque peaked little before 4K rpm where the boost was spiking.

 

Slow spool up can be caused by a small boost leak. I would check that if you haven't.[/quote']

 

I will have the car tuned to accecpt 93 pump gas when all is said and done, but I want to know the potential of this set up. This has been an ongoing project for close to 4 years and I'm just happy its finally drivable. I think my a/r on the exhaust is larger than the .63. I am trying to look for the receipt and toe tag from the turbo and give Turbonetics a call to see if they could help. On page 2 of the forum, there is an uploaded dyno sheet of my first few runs. The curve is pretty smooth, no spikes or dips. Originally, I had a Cartech wastegate installed which had a weak spring and started bleeding boost at around 180hp, so I went out and purchased a Tial 38mm gate w/ a 1 bar spring to support boost. I would assume that if there were a leak somewhere, either in the intake or exhaust to cause spiking, it would be present on the sheet. There is no sputter or hiccup in the acceleration what so ever during dynoing. Smooth and strong, but it seems to fall short when it reaches close to 6000, and don't what to push it past that point..the last thing I need is to go "back to the drawing board". Hopefully, I'll have better news Monday to post.

[yo2001]

The intake boost leak can cause spike but it makes the spool up slow since the precious compressed air is escaping out before it goes into the turbo. Plus, you will over work the turbo to create same psi. it's like tryng to blow a baloon with a pinhole. Just more work for the turbo. the harder the turbo work, more heat, more heat less power.

[Guest Cronic]

You sound a little confused with your post. Compressed air going into the turbo?

If he had a boost leak, the car would not run properly. The car would buck under boost, and run very rich. Even a slight leak would cause driveability issues. With that being said, the pop-off would cause the same issue.

[yo2001]

I meant into the intake. It'll buckle if you got a large leak like pop off or BOV prematurely opening but with a small leak, you prolly even notice much other than a slow responding turbo.

 

Since Haltec would be a speed density setup, the leak in the IC pipe before the MAP will not affect the A/F. You might get a higher intake temp than normal.

[Mack]

Id ditch the 2.5in exhaust, that is more than likely the culprit now, since you've taken the pop off valve out of the equation. that being said, switching out the stock exhaust on a stock 280ZXT to a 3in unit saw a gain of 20rwhp on the dyno. no other mods needed.

 

You are correct in assuming that these engines need backpressure to creat torque, on an NA car that is. On a turbo car, the turbo creates all the back pressure it needs and then some! so, you want the exhaust to flow as freely as possible once it gets past the turbo. It has been said time and time again, The best exhaust on a turbo car is no exhaust! Id say drop the exhaust system off from the downpipe and do a run like that, brings some earplugs tho! Im predicting a night and day difference.

 

Mack

[jeffp]

I hsve done some good testing on my turbo setup, you may want to check out my page to give you some ideas.

http://www.angelfire.com/extreme/280zxt

[81280zxtc]

I hsve done some good testing on my turbo setup' date=' you may want to check out my page to give you some ideas.

http://www.angelfire.com/extreme/280zxt[/quote']

 

Thanks for the reply. I had come across your page via link sent to me by a forum member a few days ago. I printed the dyno sheet you have posted on your page and showed it to the person tuning my car, he looked at the graph and brought to my attention it was all "all over the place", no consistent curve to follow. Although your setup is radically different, bored block and ld crank, it's unique to say the least, and I thank you for trying to help.