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Dissapointed w/ texas speed prc 227 heads and ms4 cam dyno results Part II

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Old 01-10-2018, 05:31 PM   #81
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Originally Posted by foxsl View Post
That could be a normal characteristic of nitrous as I've seen a few threads where people say the nitrous passes ran out of steam earlier in the rpm range compared to naturally aspirated.
and what was the cause of that??
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Old 01-11-2018, 07:48 PM   #82
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heres dyno graph of nos pull where it lost rpm during wot




hp RED
tq BLUE
mph LITE RED
rpm PURPLE
a/f GREEN

thoughts???. seems to be having problems at same 5800 rpm mark as the na pull where were having a loss in power. something at this part of the power curve is causing an issue

WTF IS HAPPOENIMG AT 5800 RPM AND IT ISSNT A FUEL ISSUE..
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Old 01-11-2018, 09:30 PM   #83
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Does the car nose over and change tone on the dyno? If not run it at the track. I’ve seen this on glide and th400 cars before. Are you graphing the dyno by rpm?
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Old 01-11-2018, 09:49 PM   #84
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Originally Posted by Dynospeed View Post
Does the car nose over and change tone on the dyno? If not run it at the track. Iíve seen this on glide and th400 cars before. Are you graphing the dyno by rpm?

yes we can hear it nose over as well as the change in tone in rpm when on the bottle. that was the main reason we ended both pulls early. we let it run a lil bit pass the nose over to get some numbers on the dyno and log to c what exactly it was doin. That graph had both rpm and mph.
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Old 01-11-2018, 09:54 PM   #85
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id also note that when we pulled the plugs they looked suprisingly better then what was expected the plugs to look like for a nos pull. Timing mark was right on the bend of the strap. i can confidently say that A/F is dam near perfect
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Old 01-13-2018, 12:10 PM   #86
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The way that nosed over I thought you had let off the throttle. Took me a minute to see it is that severe. Is there any chance at all there is some weird limiter that got missed on the engine or transmission side causing it to pull timing? Or if it's ETC causing it to close the blade?

That does not look like what I typically see when the cam is off. Its usually less severe when it's the cam. Any chance you have a map reading when it bodes over?
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Old 01-13-2018, 03:11 PM   #87
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Originally Posted by Darth_V8r View Post
The way that nosed over I thought you had let off the throttle. Took me a minute to see it is that severe. Is there any chance at all there is some weird limiter that got missed on the engine or transmission side causing it to pull timing? Or if it's ETC causing it to close the blade?

That does not look like what I typically see when the cam is off. Its usually less severe when it's the cam. Any chance you have a map reading when it bodes over?
yea no we didnt let off. we wanted to c exactly what was happening. if u look at it we had a loss in rpm but then started back up like something was draggin down the motor also looks like mph flatlined but then picked up while rpm was falling wich is kinda weird.dont think dave saw anything out of the ordinary like any timing being pulled or a map reading that would cause this.
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Old 01-13-2018, 04:07 PM   #88
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such a drop in power, i'd suspect valve springs. A drop in RPM whilst at WOT, also suggests valve springs. RPM should always increase at WOT.

Last edited by subeone; 01-13-2018 at 04:27 PM.
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Old 01-13-2018, 04:58 PM   #89
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such a drop in power, i'd suspect valve springs. A drop in RPM whilst at WOT, also suggests valve springs. RPM should always increase at WOT.
yea it has Pac .660 springs so i doubt it. also theres no rpm loss when we do a pull on motor... The springs were all checked as well so its safe to say its not springs
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Old 01-13-2018, 05:21 PM   #90
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i do apreciate everyones input as well as sugestions. the the car is just getting me aggitated. i know its goint to turn out to be something overlooked. But il keep at it and get it figured out..NOW IM ON A FULL BLOWN MISSION TO FIGURE THIS **** OUT...
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Old 01-13-2018, 05:40 PM   #91
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Yeah, I always figure there has GOT to be a logical solution to any problem. Usually, anyway.. lol Stay on it! You WILL get it figured out! And we are all here cheering you on!
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Old 01-13-2018, 07:43 PM   #92
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Anyway to monitor the fuel pressure at that rpm? Just trying to think out of the box.
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Old 01-13-2018, 08:11 PM   #93
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Originally Posted by 1989GTA View Post
Anyway to monitor the fuel pressure at that rpm? Just trying to think out of the box.
i dont have a gauge to monitor it. its a stock fuel system besides the drop in pump and hotwire kit..But im sure if it was low on fuel pressure id c it reflect on the A/F graph.. even Throughout the pull it never leaned out. But thats a good question tho i will def look into it... doesnt hurt to check things off the box
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Old 01-13-2018, 08:52 PM   #94
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I'm sorry if it's been asked before but what is your pushrods DIAMETER?
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Old 01-13-2018, 09:05 PM   #95
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Originally Posted by Darth_V8r View Post
I'm sorry if it's been asked before but what is your pushrods DIAMETER?
5/16. i have 7.5s in it. gave me a preload of .061
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Old 01-13-2018, 09:40 PM   #96
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I wasn't worried about preload. I was thinking pushrod flexion. Think pole-vault.

With 5/16 x 080 that's probably not the case but you could test it with a set of 3/8 or even (edit) 11/32. But it would be a $150 test

Last edited by Darth_V8r; 01-14-2018 at 06:09 PM.
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Old 01-14-2018, 12:12 PM   #97
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The way it’s falling off it looks like it shifted. Does it happen on the street too or just the dyno? What is the Nitrous set up?
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Old 01-14-2018, 04:44 PM   #98
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It looks like the nitrous turned off, when output suddenly decreases and RPM continues to climb. The picture posted is useless because it does not contain RPM or Torque data which is necessary to correlate with nitrous flow. The energy has to be going somewhere. Accidents happen when 100 horsepower worth of nitrous flow suddenly goes "missing". I am not sure it would make it to the tailpipe as the same gas it went in as...

And if the nitrous isn't "turning off" (you would expect some kind of failure, where is the energy going if not on the graph?)

I've seen this 40% likely as:
-Trigger issues (poor shielding of crank trigger wires in custom installations, i.e. ignition transistor box too close to computer or improper wiring groundings resulting in noise)
-ECU settings (surprised nobody is looking at tune file. Seems lazy to me not to check)

I would get a tooth logger going to see what the trigger is doing when it cuts out

also no more nitrous runs until you fix this issue. If it only happens during a nitrous use then it is related to the additional torque/pressure supplied by the nitrous, or the increase rate of change of the engine acceleration which affects some ECU settings.

Other possible sources (probability in %)
-spark blowout 5% (unlikely as engine continues to accelerate)
-ignition dwell time coil current low 5% (might be passing into a "low dwell" area although wouldn't this also cause blow-out?)
-loss of valve control in the head (somebody said pushrods) 15% (so suddenly, though so smooth?)
-sudden loss of fuel pressure (somebody mentioned) 15% (could definitely be this however unlikely, O2 has a slight delay reading but at that RPM it should not be much)
-Bad ECU / corrupt file 25%
-converter/trans failure? Not sure % for non 9.5" lockup models

Just tryin'a help as usual

Its 4:1 that this is a computer related issue when the source isn't the liquids you are feeding the engine

Last edited by kingtal0n; 01-14-2018 at 05:29 PM.
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Old 01-14-2018, 06:11 PM   #99
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That's a good thought about the nitrous. And I had thought about mentioning the bottle possibly getting cold as it ran.

But it does the same thing NA. Its a weird one for sure.
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Old 01-14-2018, 10:02 PM   #100
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Problem is inability to get proper cylinder Fill as RPM's increase. When he threw the Nitrous to it it made the problem that much.

All he has to do is figure out why.

If it's not intake, the heads, the cam, the pushrods, the 1 7/8" headers, then could it be that length of 2 1/2" single exhaust pipe causing exhaust "Back Pressure" not allowing good incoming intake charge fill because of amount of spent Exhaust gases still in cylinder? Effective exhaust flow is 2 1/2", not 3.0"

Sure some people with "Y" pipes don't have as much of a problem, but at some point of chasing HP, even a great "Y" single exhaust pipe can't flow to engine's potential.

By the way what RPM is the cam designed to make Peak HP at.
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