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Re: The 541 is headed to the dyno! Any guesses? [Re: csk] #3061006
07/20/22 03:54 PM
07/20/22 03:54 PM
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Quote
I'm running Gatorman lifters and Comp 1.5 rollers. The valve train was very quiet. Quieter than I expected. When it ran into valve float the engine started dancing around.


That would be a new one for me.

I’d expect the Gatorman lifters to hang on well beyond 5200 with those cam lobes and 1.5 rockers........ provided the springs and pushrods are stiff enough.
If the springs seem to be correct, and set up properly, then it nosing over at 5200 might just remain a bit of a mystery for the time being.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: The 541 is headed to the dyno! Any guesses? [Re: fast68plymouth] #3061120
07/20/22 09:58 PM
07/20/22 09:58 PM
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I used these springs: https://www.compcams.com/dual-valve-springs-1-509-o-d-outer-697-i-d-inner-3.html


Max Lift: 0.665
Installed Height: 1.9
Coil Bind Height: 1.175
O.D. of Outer: 1.509
I.D. of Inner: 0.697
I.D. of Outer: 1.125
Spring Style: Dual
Spring Rate: 395
Seat Pressure: 111
Damper: Yes

Well, dance around may be a bit strong. When it got up close to valve float the engine began to wiggle around.

I was eyeing the Holley datalog. Intake air temp was hovering around 130 degrees.
Yeah, the cell was a bit warm.


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: The 541 is headed to the dyno! Any guesses? [Re: AndyF] #3061128
07/20/22 10:12 PM
07/20/22 10:12 PM
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Originally Posted by AndyF

Cam is small so that will restrict the power but you should have great torque. I'm going with 650 torque and 525 hp as a guess. Hopefully it starts, runs good and doesn't leak. If it does those three then it is a successful dyno day. Fine tuning can always take place down the road. Are you confident of the EFI tune at this point or will you need to dial in that tune on the dyno?



It looks like I edged out the mighty AndyF with my power guess over on the discussion page.

Originally Posted by feets
I think you're a wee bit optimistic. My guess is 542 hp and 649 lb/ft.


biggrin


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061221
07/21/22 07:36 AM
07/21/22 07:36 AM
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Originally Posted by feets
I used these springs: https://www.compcams.com/dual-valve-springs-1-509-o-d-outer-697-i-d-inner-3.html


Max Lift: 0.665
Installed Height: 1.9
Coil Bind Height: 1.175
O.D. of Outer: 1.509
I.D. of Inner: 0.697
I.D. of Outer: 1.125
Spring Style: Dual
Spring Rate: 395
Seat Pressure: 111
Damper: Yes

.


That is not a hydrualic roller spring in my opinion. Should be 140-150 on the seat and at least 400 open. From what I can tell your around 110 on the seat and 335 open.

Re: The 541 is headed to the dyno! Any guesses? [Re: B1MAXX] #3061246
07/21/22 09:21 AM
07/21/22 09:21 AM
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I suspected you may have had Comp 925’s on the heads.

I’d change them if it were me.

Way easier to do it now before the motor goes in the car.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: The 541 is headed to the dyno! Any guesses? [Re: B1MAXX] #3061249
07/21/22 09:53 AM
07/21/22 09:53 AM
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Originally Posted by B1MAXX


That is not a hydrualic roller spring in my opinion. Should be 140-150 on the seat and at least 400 open. .


Agreed


69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 595rwhp 475rwtq.
Re: The 541 is headed to the dyno! Any guesses? [Re: fast68plymouth] #3061407
07/21/22 03:19 PM
07/21/22 03:19 PM
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What's your recommendation for better springs?


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061415
07/21/22 03:26 PM
07/21/22 03:26 PM
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Originally Posted by feets
Originally Posted by AndyF

Cam is small so that will restrict the power but you should have great torque. I'm going with 650 torque and 525 hp as a guess. Hopefully it starts, runs good and doesn't leak. If it does those three then it is a successful dyno day. Fine tuning can always take place down the road. Are you confident of the EFI tune at this point or will you need to dial in that tune on the dyno?



It looks like I edged out the mighty AndyF with my power guess over on the discussion page.

Originally Posted by feets
I think you're a wee bit optimistic. My guess is 542 hp and 649 lb/ft.


biggrin


Watch it now, he is a site sponsor, better keep quiet and stay out of trouble laugh2.


Rich H.





Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061434
07/21/22 04:05 PM
07/21/22 04:05 PM
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Originally Posted by feets
What's your recommendation for better springs?


I’d have used the Isky 8005A, installed at 1.840-1.850.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: The 541 is headed to the dyno! Any guesses? [Re: fast68plymouth] #3061460
07/21/22 05:36 PM
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Set the springs you have to 1.8 and you get 150-415 or thereabouts.

Re: The 541 is headed to the dyno! Any guesses? [Re: ZIPPY] #3061498
07/21/22 08:09 PM
07/21/22 08:09 PM
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The 496 in my Coronet made 613 hp and 631 torque so one could argue that I only gave up a tiny bit of torque to pick up a bunch of power. But, I have a feeling that the cam used in my 496 would not be happy pulling a heavy Imperial down the freeway at 1800 rpm. It would probably pull the car down the racetrack a little faster, but cruising in OD is a really tough trick for a performance engine.

I'm not convinced that the induction system on that engine is great for that application but it would take a bunch of testing to find a better one that fit under the hood so I think it is what it is.

Re: The 541 is headed to the dyno! Any guesses? [Re: AndyF] #3061504
07/21/22 08:41 PM
07/21/22 08:41 PM
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Originally Posted by AndyF
The 496 in my Coronet made 613 hp and 631 torque so one could argue that I only gave up a tiny bit of torque to pick up a bunch of power. But, I have a feeling that the cam used in my 496 would not be happy pulling a heavy Imperial down the freeway at 1800 rpm. It would probably pull the car down the racetrack a little faster, but cruising in OD is a really tough trick for a performance engine.

I'm not convinced that the induction system on that engine is great for that application but it would take a bunch of testing to find a better one that fit under the hood so I think it is what it is.


I knew my build was going to throw away a lot of easy power but it makes no sense to build an engine that won't do what the car needs. Looking at the datalog the engine was idling around 48 kpa. That'll keep the power brakes happy. There should be no such thing as a soft bottom end on this motor and I imagine it'll be happy dragging the Imperial around.

As for the intake, I had it so it went on. I expected it to fatten the middle of the curve but I didn't think it would quit that hard and fast.

I explored the idea of TF 270s but I couldn't find a decent intake that would fit under the low hood and work with the MW ports.


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061507
07/21/22 08:54 PM
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Yeah I agree with your decisions. They aren't perfect but they are the best you can do with the resources that you have. It would require a major R&D effort to optimize an intake manifold that engine in that engine bay. And the camshaft choice just has to be what it is or else that engine won't work right in that car. My engine idles at 58 kpa which is significantly rougher than 48 kpa. My engine would have significantly worse gas mileage on the freeway than your engine just due to the slightly larger duration at 0.050 and the little bit of extra overlap.

Re: The 541 is headed to the dyno! Any guesses? [Re: AndyF] #3061526
07/21/22 10:26 PM
07/21/22 10:26 PM
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If I could pick your mind a bit more...

When the power fell off the engine began to wiggle around a bit. I didn't notice any jumps in the rpm. In the first pull we hit the suspected valve float and the engine dances around a bit. The second pull shut off a bit earlier to go easy on it and there was hardly any wobble. Pull number three went a little higher again and it was back to bobbling about.

Can valve float and/or the intake giving up cause it to waggle only in that part of the pull? It is rather amusing to see the camera get all twitterpated with the harmonics in the room.



We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061528
07/21/22 10:41 PM
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I suspect engine balance rather than valve float or intake ram effect. Could be the engine or the dyno driveshaft but looks to me like the engine gets into a harmonic wobble at a certain RPM.

Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061566
07/22/22 08:49 AM
07/22/22 08:49 AM
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Originally Posted by feets


When the power fell off the engine began to wiggle around a bit.


Not really surprising to me, it's like throwing the brakes on the entire setup.

I would say after posting your spring pressures that valvetrain instability is confirmed rather than suspected. (so fixing that should make a huge difference)


69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 595rwhp 475rwtq.
Re: The 541 is headed to the dyno! Any guesses? [Re: B1MAXX] #3061583
07/22/22 10:47 AM
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Originally Posted by B1MAXX
Set the springs you have to 1.8 and you get 150-415 or thereabouts.


I’m not sure how you’re coming up with that.

Valve lift = .590
Spring rate is 395lbs/in
395 x .590 = 233
233 + 150 = 383

For something that’s going to see a lot of miles, I’d prefer to not have the springs set so close to coil bind.
The 925 is 151lbs @1.800, and coil binds at 1.175”....... so .625” available travel -.590” valve lift is .035” from coil bind.

If one really felt like they needed over 400lbs open load(which only exacerbates the lifter collapse/bleed down scenario) in this application, you’d want to use a spring with a higher rate....... like a Comp 929(439lbs/in).

439 x .590 = 259
259 + 150 = 409

Quote
I would say after posting your spring pressures that valvetrain instability is confirmed rather than suspected. (so fixing that should make a huge difference)


Actually, I didn’t see where it was posted what the spring loads are....... just what the springs themselves are.
Depending on exactly how the springs are set up, the loads may or may not be way too light for the application.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: The 541 is headed to the dyno! Any guesses? [Re: feets] #3061595
07/22/22 11:23 AM
07/22/22 11:23 AM
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On the 1st and 3rd dyno pulls, I can hear the engine start to get a little ratty at the top of those pulls.

You can also look at the dyno sheet and see that the acceleration rate isn’t real steady at the top, and the computer is making big changes to the load trying to chase/maintain a smooth/constant rate.

Andy, how high did you make pulls on the 496?
That cam used lobes from the same families as feets cam.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: The 541 is headed to the dyno! Any guesses? [Re: fast68plymouth] #3061669
07/22/22 04:34 PM
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We pulled to 6200 or 6300 rpm. I don't have all of the dyno sheets here in my office but I don't recall any valve train issues. But I used the conical valve springs from Comp. That engine probably didn't need the conical springs but I thought they were cool and I had used them on a previous build so I went with them.

DSC_4371 (Large).JPG
Re: The 541 is headed to the dyno! Any guesses? [Re: AndyF] #3061677
07/22/22 05:50 PM
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All the conical springs from Comp(if that’s where you got them) have a pretty high rate.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
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