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Weird dyno with dip at 7,000

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Old Apr 18, 2004 | 03:59 PM
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Weird dyno with dip at 7,000

I have:
downpipe, midpipe, catback, denso fuel pump, intake, airpump removed and the Power FC.

I had the car tuned and dynoed by Jason at the RX7store, and everything was normal. Was tuned for low 11s in boost, at 12PSI. I asked several people and I heard consistantly that I should make 290-310 RWHP with these mods.

The graph looked really weird. There was a dip at 5000-5500 and then a big dip at 7000 on both graphs.




First what I dont get is: Why am I making 340RWHP with these mods. Ive got a stock motor, stock twins with 62k on them.

Jason said that the car is definintely healthy, because they did several pulls to tune and he also drove it on the street to make sure everything was okay. He said that there was something messed up with the dyno.

So is my car god-like or was the dyno messed up, or was there something wrong with my car, ignition or something.

I'm not questioning Jasons tuning, the car runs great, but the graphs look weird.

This was on a mustang dyno
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Old Apr 18, 2004 | 05:23 PM
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I have no clue. Damn good power though if thats the real readings and the dyno wasn't messed up. But really I'm not sure. As for the dips I don't know about that either.....ummmm, possible ground issues? I really don't know bud, cause I know nothing about your car or what its been through etc. There's probably someone on here that has had similar problems and know what's wrong. Or maybe it was just the dyno like you said, Jason was saying it was messed up. But who knows, cause I don't
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Old Apr 18, 2004 | 05:32 PM
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320-340 is more like it with intake, full exhaust, PFC, and 12isp psi of boost. I ran a 12.3@113 with those mods and that mph translates into around 330rwhp.

Anyway, can you post your a/f chart? Is there anything wierd about the boost? Can you feel this on the road, you definatly should be able to feel it. What form of boost control do you have? It definatly looks boost related to me. It never really seems to recover from transition, most charts I've seem make a good 50rwhp or more when coming out of transition

STEPHEN
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Old Apr 18, 2004 | 05:35 PM
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The more I look at it the more it really looks like your 2nd ary isnt fully spooled up at transition like its supposed to be. This means your power is still being created by just the pri turbo, then it starts to die off in the high rpms and the 2nd turbo finially starts to pick up steam toward the very end. This would also explain why you dont have that big jump in power coming out of transition.

I think its a pre spool problem, or at least something keeping the seconday turbo from getting boost when its supposed to. Maybe a leak at turbo/ypipe connection. Or maybe the crv is leaking. Who knows it could be anythink 2nd turbo related

STEPHEN

Last edited by SPOautos; Apr 18, 2004 at 05:39 PM.
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Old Apr 18, 2004 | 05:57 PM
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Re: Weird dyno with dip at 7,000

Originally posted by Rx-7Addict
This was on a mustang dyno
So you made more power on a dyno that is known to read low? Wow, hey good job!

Little odd but I wouldn't be complaining.
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Old Apr 18, 2004 | 06:13 PM
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Actually, you are not really making 340 HP. You spiked to 340 HP. At most, you are making about 280-290 useful HP.
As SPOautos said, there is something wrong with your turbo control system. The first graph doesn't even register the primary comming on line. The second graph shows a better transition for the primary @3000 rpm. Judging from the graphs, I'll bet your primary is boosting high very quickly and the secondary is not comming online when it should and when it does come on line it's not holding boost.
In both cases, you power drops to 200 HP or below, that is big enough so if you drive it on the road you should be able to feel it.
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Old Apr 18, 2004 | 09:44 PM
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ttt
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Old Apr 18, 2004 | 11:26 PM
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is your car running seq or non-seq if seq that dip might be your turbo transition
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Old Apr 18, 2004 | 11:44 PM
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It is still the stock sequential. I am more worried about the dip at 7000 RPM, which should not be a transition
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Old Apr 19, 2004 | 03:01 AM
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when i dynoed at the rx7store, i had a dip that hit the bottom of the chart at around 7k. i think it was a software glitch or something. the car doesn't have a bit of hesitation. they also use a mustang dyno. i've been on a local dynojet and it's done the same thing a few times. it's actually a lot more common than you'd think

EDIT: just noticed you said Jason, so i'm guessing you were at rx7store as well
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Old Apr 19, 2004 | 03:33 AM
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well, the forum is being gay. i just tried 5 times to upload a pic of my dyno to no avail. i'll try again tomorrow. but it dips in the same spot, and drops to about 100hp


Last edited by spoolin93r1; Apr 19, 2004 at 03:38 AM.
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Old Apr 19, 2004 | 09:00 AM
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Everyonce in a while the chart will dip at 7K, not all the time. Im not sure why it does that. I can look at the raw and trace data which is smooth thru the powerband.

Rx-7Addicts boost was rock solid thru the runs. I will try to post a copy of the trace data. A/F's were right around 11.2 all the way up with no hesitation. Car runs strong.

Im thinking that the tach signal on the dyno was messed which would be causing the irregular looking graphs.

I have our dyno setup to read Dynojet Numbers.

Jason
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Old Apr 19, 2004 | 09:09 AM
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Originally posted by Jason
I have our dyno setup to read Dynojet Numbers.
Crafty Jason.

Well I guess thats your answer addict, it's just a software thing, not your car.
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Old Apr 19, 2004 | 09:57 AM
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Originally posted by 911GT2
Crafty Jason.

Well I guess thats your answer addict, it's just a software thing, not your car.
Yea, thats what Jason said. I cetainly agree with him and I guess its not really important anyways, the car feels good, and it was there to get tuned, not dynoed

not sure if my peak of 340 is still accurate
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Old Apr 19, 2004 | 10:18 AM
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Originally posted by SPOautos
320-340 is more like it with intake, full exhaust, PFC, and 12isp psi of boost. I ran a 12.3@113 with those mods and that mph translates into around 330rwhp.
STEPHEN
i disagree..95% of people with those mods and 12 psi usually make 290- 305 rwhp. The reason you ran such a great trap was either your car is a freak or u are running alittle more boost then u think. Actually with my old setup of intake full exhauist, power fc i was trapping 110 mph ( and i made 298.9 rwhp ). so your trap of 3 mph greater isnt that abnormal....just a;little higher then most.
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Old Apr 19, 2004 | 11:09 AM
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Is it possible that it could be high RPM break up and he may need better spark. Yet I do lean toward the boost issue. Non-sequantial time
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Old Apr 19, 2004 | 11:23 AM
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i definately agree with jason, about the software glitch. Because if spoolin93r1 all the sudden lost 300 hp you would definately feel that ****
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Old Apr 19, 2004 | 11:27 AM
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hey spoolin93r1 how much boost are you running
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Old Apr 19, 2004 | 11:28 AM
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Originally posted by Fatman0203
Is it possible that it could be high RPM break up and he may need better spark. Yet I do lean toward the boost issue. Non-sequantial time
They put new plugs in before the dyno. I shouldnt need new ignition yet
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Old Apr 19, 2004 | 02:55 PM
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Originally posted by Jayseven
hey spoolin93r1 how much boost are you running
16psi is what the defi gauge said. we had a pull that showed 439, but the 432 sheet got printed out. i was pretty pleased
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Old Apr 19, 2004 | 03:38 PM
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If your car is running good, then the dyno is screwed up. You would definitely feel the drop in power that the dyno says is happening at 7K. If you are not feeling it, the dyno is malfunctioning. It is probably also malfunctioning when indicating 340 hp.

Last edited by adam c; Apr 19, 2004 at 03:42 PM.
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