Valve float issues on dyno

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Re: Valve float issues on dyno

Post by maxracesoftware »

hoffman900 wrote: Fri Mar 16, 2018 5:54 pm
maxracesoftware wrote: Fri Mar 16, 2018 2:56 pm the Dyno Air Turbine ( if they have one ?? )
will immediately tell you if its really Valve Float issue
Larry, Jay, or anyone,

What metric would you be looking for to distinguish timing vs. say valve float?
Bob ,

with the Air Turbine , you would look at these readings for evidence of Valve Float :
[1]= easy ... TQ and HP fall-off quickly the higher the RPM , and BSFC's climb very rapidly in that same RPM Band

[2]= Air Turbine CFM readings--> as RPMs climb, CFM levels off or can also fall-off rapidly
or can level-off somewhat before Peak HP RPM, then climb a little more, then really level-off once again, then higher RPM drop off quickly

[3]= Air Turbine CFM readings--> Look for the "CFM Rate of Change" .... basically like #[2] above, but the 'Rate" slows down quickly with Valve Float
at mid to high RPM

[4]= Air Turbine CFM readings--> Look for the "Volumetric Eff % Rate of Change" .. this is just same thing as #[3] above

i've seen the Air Turbine CFM level-out maybe drop slightly , then as RPM climbs, the CFM starts climbing again,
then a little higher in RPM, it levels off again, and going even higher RPM, the CFM and VE% drop very quickly .
....it would appear the Springs are doing a 'dance" :) at a lower RPM , then a little higher RPM, the springs are back in control,
then even higher RPM, severe Valve Float comes back .

air up the Cylinders and change to higher pressure Valve Springs ,
gain something like 25+HP at 7000 RPM on a 550 HP Engine
and now Air Turbine shows a steady "Rate of CFM increasing" as RPMs climb to 7000 RPM and above

this is just simple examples, you can loose a bunch more than 25 HP on higher RPM , higher HP engines

and just one more Note :
i only will make a few Pulls with the Air Turbine on,
just to see CFM and VE and check for Float ,
after that i remove the Air Turbine and do the rest of the Dyno testing without it .

reason--> the Air Turbine has length and can effect Total Induction Length Tunning
and the other reason is that most all Carbs will breathe a bunch of Air from around the sides of the Top of the Carb,
and the Air Turbine body is restricting AirFlow coming into or turning into the Carb at its top sides of Venturi Entries .
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user-23911

Re: Valve float issues on dyno

Post by user-23911 »

A WB o2 gauge will show what's going on.

An ignition misfire spikes lean, a valve bounce won't.

Likewise an EGT probe might go colder, might not but might show if it's one or all cylinders dying.
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Re: Valve float issues on dyno

Post by WPH »

joe 90 wrote: Sat Mar 17, 2018 5:17 am A WB o2 gauge will show what's going on.

An ignition misfire spikes lean, a valve bounce won't.

Likewise an EGT probe might go colder, might not but might show if it's one or all cylinders dying.

Would WBO2 show overly rich condition and not response changes on a fuel map ?


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Re: Valve float issues on dyno

Post by lekid »

Hi guys,

Sorry, been busy the last few days. This dyno was the first time we went and it is a new dyno, and with that growing pains. Unfortunately, those growing pains did not help with our issue. He does not have an air turbine and he had issues with his AFR sensor. He figured it out on the next motor. He was using a 6al ignition box with a blaster coil, so we thought maybe the box couldnnot handle it, sonhe installed a 7al with an HVC 2 coil, same issue. The carb felt like whatever fuel we added, didn't show the fuel gains on the plugs: went up 5 jets and plug looked the same and very little change in hp from such a big change (we now realize the problem was properly related to the issue we found). We did change the carburetor and no changes. We went from 600 rpm/second to 300 rpm/second and it got worse! The weird part was that even though the engine was losing TONS of power and sounded like it was breaking up, it would continue to climb in RPM!! Valv float usually will usually not do that from my limited experience.

I tested some springs on the engine with a Buxton tester and some seemed a little low but never used that particular tool, so hard to compare to what they were new. I took 3 springs off the motor (2 worse ones and the best one based on the on-engine tester). I brought them to my machine shop and we used his good on-bench tester. All 3 springs were within 5lbs of each other and Chad Speier took one new spring out of the box and tested it on his side and my springs are within 5-10lbs from new ones. Springs are not the issue!!

The camshaft might be the issue. It was an experiment and I will put the old one from last year back in since I know what it makes for power, I know it works great in the car and with the current converter and no issues going to 7700 or above rpms.

After discussing my issue with Chris Uratchko and a few others, we all agreed that he did seem like ignition and Chris has seem the crank trigger fail at high rpms NUMEROUS times. I tested the sensor as per MSD instruction and they said it should be between 65-86 ohms and nine is at 7 ohms.

People asked about pushrods and they are Manton Series 5 - 3/8" with 0.145" wall. We cannot fit bigger than 3/8". I spoke to Al@Manton when we changed cam and he confirmed that the pusbrods wouldnbe sufficient. After out issue, I called him back and he did explain that if it is a frequency issue, he can change wall to help move the frequency around, but that he believed my pushrods were sufficient. (I did provide him lifter, valve, retainer abd locks weight).

Thanks for all the responses. I believe the problem is the crank trigger sensor, but I will put the old custom grind CompCam back in, set my heights for around 0.050" from coil bind and go from there.
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Re: Valve float issues on dyno

Post by Warp Speed »

joe 90 wrote: Sat Mar 17, 2018 5:17 am A WB o2 gauge will show what's going on.

An ignition misfire spikes lean, a valve bounce won't.

Likewise an EGT probe might go colder, might not but might show if it's one or all cylinders dying.
Actually, intake valve bounce typically goes lean, exhaust bounce will show rich.
An ignition problem will also show lean, typically worst through peak torque.
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Re: Valve float issues on dyno

Post by hoffman900 »

Thanks Larry and Jay. That's a big help.
-Bob
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Re: Valve float issues on dyno

Post by Warp Speed »

lekid wrote: Sat Mar 17, 2018 8:33 am Hi guys,

Sorry, been busy the last few days. This dyno was the first time we went and it is a new dyno, and with that growing pains. Unfortunately, those growing pains did not help with our issue. He does not have an air turbine and he had issues with his AFR sensor. He figured it out on the next motor. He was using a 6al ignition box with a blaster coil, so we thought maybe the box couldnnot handle it, sonhe installed a 7al with an HVC 2 coil, same issue. The carb felt like whatever fuel we added, didn't show the fuel gains on the plugs: went up 5 jets and plug looked the same and very little change in hp from such a big change (we now realize the problem was properly related to the issue we found). We did change the carburetor and no changes. We went from 600 rpm/second to 300 rpm/second and it got worse! The weird part was that even though the engine was losing TONS of power and sounded like it was breaking up, it would continue to climb in RPM!! Valv float usually will usually not do that from my limited experience.

I tested some springs on the engine with a Buxton tester and some seemed a little low but never used that particular tool, so hard to compare to what they were new. I took 3 springs off the motor (2 worse ones and the best one based on the on-engine tester). I brought them to my machine shop and we used his good on-bench tester. All 3 springs were within 5lbs of each other and Chad Speier took one new spring out of the box and tested it on his side and my springs are within 5-10lbs from new ones. Springs are not the issue!!

The camshaft might be the issue. It was an experiment and I will put the old one from last year back in since I know what it makes for power, I know it works great in the car and with the current converter and no issues going to 7700 or above rpms.

After discussing my issue with Chris Uratchko and a few others, we all agreed that he did seem like ignition and Chris has seem the crank trigger fail at high rpms NUMEROUS times. I tested the sensor as per MSD instruction and they said it should be between 65-86 ohms and nine is at 7 ohms.

People asked about pushrods and they are Manton Series 5 - 3/8" with 0.145" wall. We cannot fit bigger than 3/8". I spoke to Al@Manton when we changed cam and he confirmed that the pusbrods wouldnbe sufficient. After out issue, I called him back and he did explain that if it is a frequency issue, he can change wall to help move the frequency around, but that he believed my pushrods were sufficient. (I did provide him lifter, valve, retainer abd locks weight).

Thanks for all the responses. I believe the problem is the crank trigger sensor, but I will put the old custom grind CompCam back in, set my heights for around 0.050" from coil bind and go from there.
Your problem would be typical of a bad pick up, and apparently your ohm readings verify. As I said earlier, a secondary breakdown is worst at peak torque, and pick up and/or gap problem will typically deteriorate with rpm.
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Re: Valve float issues on dyno

Post by Nikolas Ojala »

Have same valves, springs etc. but less aggressive cam profile (i.e. less jerk, less acceleration and less speed). Your engine will run higher rpm without valvetrain issues, so it will produce more power because you can let the engine run faster than before. How much your engine will lose torque at low speed with such cam, I don't know. If you are worried about loss of torque at low speed, this solution may not be for you.
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Re: Valve float issues on dyno

Post by af2 »

Learned a new one at the March Meet. Guy running a blown 570" big block has to run .020" on the pickup to get it to fire. Hey had tried 2 different PU's and wheel and they were all the same. I didn't look to see what box though.

Just a thought.
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Re: Valve float issues on dyno

Post by maxracesoftware »

i thought about this when i first read this Thread ,
but did not Post anything because i presumed they had EGT's or O2 Sensors and/or Air Turbine

this is just additional info for anyone reading this Thread , and probably will not exactly or remedy his problem

Info : its a Post on my Private Forum Link :
http://www.maxracesoftware.com/bulletin ... =70&t=1629

entitled = "How to make a 1038+HP Engine make 770 HP"
By putting on a brand new Out-the-Box Moroso Crank Trigger setup :oops:

after OHM'ing all the plug wires + coil wire , + everything else we could think of
found out the real problem was 1 magnet of the Crank Trigger wheel had wrong polarity :oops:

3 magnets repelled my pocket magnet
1 magnet stuck to my magnet :D ..... that was same magnet firing the 2 Cylinders that were showing they were dead !

Racers going back to Baton Rouge picking up new MSD Crank Trigger setup
and in a couple of hours we should know results ??

Note : i've seen Pickups wired wrong , but 1st time seeing magnet North/South poles installed wrong

Engine would show heat in those 2 Cylinders idleing, but under full-throttle Dyno load , no spark in those 2 cylinders
controlled by the 1 bad magnet
"BBC 588.5 cid 4.500x4.625 small Bore shrouding Valves = 2.400/1.850 Edelbrock 24deg

made 1120.4 Peak HP at 7900 RPM
Peak TQ = 817.9 at 6400 RPM

did not put the new Carb on , might have made more HP"

maxracesoftware wrote:
Like Forest's momma used to say....ya never know what yer gonna get.

Amazingly the HP per cyl almost works out correctly.
Gump was right :)

BBC 588.5 cid 4.500x4.625 small Bore shrouding Valves = 2.400/1.850 Edelbrock 24deg

made 1120.4 Peak HP at 7900 RPM
Peak TQ = 817.9 at 6400 RPM

did not put the new Carb on , might have made more HP
here's actual Dyno sheet Data...went from 770 HP to 1120.4 :)

JeffC_BBC589_1120HP.png
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