Interesting 540 dyno test
#3169050
08/19/23 04:23 PM
08/19/23 04:23 PM
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Joined: Jan 2003
Posts: 31,074 Oregon
AndyF
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We're running a 540 BBC on the dyno this week and it isn't going very well. The engine just won't rev past 6000 rpm. It is a hyd roller cam so that is the obvious suspect but it doesn't make any valvetrain noise at 6000 rpm and it has the correct springs in it and plenty of oil pressure. We actually think the problem is due to something weird in the EFI system and/or the intake manifold itself. We're going to switch over to a carb next week to see what happens. This engine has been on the dyno before and last time it acted weird. It has a lot of really good parts but something isn't correct somewhere. Hopefully we can figure it out. Here is a short video showing two dyno pulls back to back: https://youtu.be/4q-tV1mNl-gEngine is making 730 hp on these pulls so it isn't a slouch, but it should be making more and it should be pulling higher so something is wrong somewhere. Plugs all look good, EGTs are normal, AFR is normal, etc. so no obvious clues.
Last edited by AndyF; 08/19/23 04:27 PM.
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Re: Interesting 540 dyno test
[Re: AndyF]
#3169062
08/19/23 05:25 PM
08/19/23 05:25 PM
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Joined: Feb 2008
Posts: 715 Central TEXAS!!!!
sr4440
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super stock
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Central TEXAS!!!!
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What kind of EFI system, can you post a log?
Without Data, you’re just another guy with an opinion.
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Re: Interesting 540 dyno test
[Re: AndyF]
#3169088
08/19/23 07:49 PM
08/19/23 07:49 PM
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Joined: Jan 2003
Posts: 10,757 North Dakota
6PakBee
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What does the BSFC do at the top of the rpm range?
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Interesting 540 dyno test
[Re: 6PakBee]
#3169100
08/19/23 09:17 PM
08/19/23 09:17 PM
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Joined: Jan 2003
Posts: 31,074 Oregon
AndyF
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What does the BSFC do at the top of the rpm range? Looks normal but you can't always trust the data since the fuel flow on an EFI engine is what the ECU is commanding, not what actually flows. Usually the same thing unless something weird is happening.
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Re: Interesting 540 dyno test
[Re: fbs63]
#3169234
08/20/23 03:25 PM
08/20/23 03:25 PM
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Joined: Jan 2003
Posts: 31,074 Oregon
AndyF
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Chinese casting heads? Asking because I have seen this happen with various brands and makes of engines. Yeah I've seen that several times including BB Chevy engines. The really cheap no name Chinese stuff works okay for a cruiser but won't make power at WOT. But that shouldn't be the case with this engine since the customer bought really nice parts including a Dart block and AFR 335 cnc heads. It isn't a high compression engine since it is heading into a street car, but my 470 Mopar with TF270 heads made more power on pump gas than this 540 is making. AFR 335 BB Chevy heads should flow a ton more air than Trick Flow Mopar 270 heads and 540 is 70 inches bigger than my 470 so something isn't clicking. We'll get some runs on it this week with a 1050 Dominator and a MSD billet distributor and see what happens.
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Re: Interesting 540 dyno test
[Re: AndyF]
#3169288
08/20/23 07:56 PM
08/20/23 07:56 PM
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Joined: Nov 2003
Posts: 1,841 NW Indiana
fbs63
top fuel
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top fuel
Joined: Nov 2003
Posts: 1,841
NW Indiana
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Chinese casting heads? Asking because I have seen this happen with various brands and makes of engines. Yeah I've seen that several times including BB Chevy engines. The really cheap no name Chinese stuff works okay for a cruiser but won't make power at WOT. But that shouldn't be the case with this engine since the customer bought really nice parts including a Dart block and AFR 335 cnc heads. It isn't a high compression engine since it is heading into a street car, but my 470 Mopar with TF270 heads made more power on pump gas than this 540 is making. AFR 335 BB Chevy heads should flow a ton more air than Trick Flow Mopar 270 heads and 540 is 70 inches bigger than my 470 so something isn't clicking. We'll get some runs on it this week with a 1050 Dominator and a MSD billet distributor and see what happens. Good to know. Interested to see what it is!
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Re: Interesting 540 dyno test
[Re: AndyF]
#3169303
08/20/23 08:58 PM
08/20/23 08:58 PM
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Joined: Jan 2003
Posts: 10,757 North Dakota
6PakBee
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I Live Here
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What does the BSFC do at the top of the rpm range? Looks normal but you can't always trust the data since the fuel flow on an EFI engine is what the ECU is commanding, not what actually flows. Usually the same thing unless something weird is happening. It will be interesting to see what happens with a carb. That should eliminate the uncertainty with EFI.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Interesting 540 dyno test
[Re: AndyF]
#3169654
08/22/23 12:28 PM
08/22/23 12:28 PM
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Joined: Jan 2003
Posts: 14,514 So. Burlington, Vt.
fast68plymouth
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Unless you’re duplicating a known good valve train combo....... big block weight parts, high rocker ratios, Hyd lifters and higher rpm’s can be a challenge to get sorted out.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Interesting 540 dyno test
[Re: fast68plymouth]
#3169774
08/22/23 07:12 PM
08/22/23 07:12 PM
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Joined: Jan 2003
Posts: 31,074 Oregon
AndyF
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Unless you’re duplicating a known good valve train combo....... big block weight parts, high rocker ratios, Hyd lifters and higher rpm’s can be a challenge to get sorted out. I agree. We proved to ourselves that the upper rev limit is the lifters. The lower RPM roughness appears to be manifold related. EGT values are all over the map at 2000 rpm but they smooth out at higher revs. The weird pulsing issue was due to the poor fuel rail design and the undersize fuel pressure regulator.
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Re: Interesting 540 dyno test
[Re: AndyF]
#3169865
08/23/23 10:08 AM
08/23/23 10:08 AM
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Joined: May 2019
Posts: 713 Lake Villa Il
INTMD8
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Lake Villa Il
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Did you try more valve spring? Or lighter springs/retainers. (smaller OD, titanium)
I've yet to see a loss of valve control come down to the lifter itself. JMO
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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