NA Engine With No Damper?

[RDY4WAR]

I've been researching engine harmonics this morning (mostly out of boredom) and got to thinking about the effect of a damper on an internally balanced engine. I tried googling the topic but I got mostly people running no damper with a blower so wasn't much help.

The engine in question would be a '93 Gen-2 LT1 SBC which is internally balanced in the front and external rear. The goal is to free up as much power as possible for drag racing only (no street time). The engine has the OEM rotating assembly with the stock 3.48" cast crank and turning a max of 6250 rpm. The OEM damper is 7.5" and weighs ~12 lbs and is turning only an alternator with serpentine belt. This engine has stock heads, cam, and intake making ~320 rwhp @ 5200-5400 rpm.

What I'm wondering is if you could replace the damper with just a pulley to turn the alternator?

Given the limited rpm and dragstrip only use, would the harmonic effects be catastrophic?

Increased bearing wear and crank fatigue would obviously be a factor. Could a 6-rib serpentine belt provide some absorption of harmonics?

[pdq67]

if you want to look into it, when the 1st 265 SBC came out, it just had a hub on it.

Please check me out here some of you OLD guys.

Fwiw, I had a STOCK, 265/PG Belaire H/T back then, wished I still had it. It had a top can oil filter on it, weird.. Like a Stude V-8 had if I remember right?

pdq67

[bthomas]

Iirc vizard did tests on this topic, and no damper lost power. Actually going to bigger damper increased power.

[bthomas]

Found it


viewtopic.php?t=8965

[Firechicken]

Some Pontiac V8 engines in the 70s were factory built with just a hub but they only revved to about 4500.

[BlitzA64]

Iirc vizard did tests on this topic, and no damper lost power. Actually going to bigger damper increased power.

Yet many people jump through hoops to shave crankshaft weight on some performance engines. Do to application, not necessarily by choice I have run many engines without dampers and saw no bad results in bearing wear on them. I digress, 1 inline 4 had one funky main bearing, I opened up the clearance on that one bearing and all looked new on the next refresh. Not sure if it is worth anything on the track but accelerating the damper weight should cost something measurable or not.

[frnkeore]

I can't remember seeing a F1 engine with a dampener.

[lefty o]

the right dampener will actually gain you power.

[maxracesoftware]

the right dampener will actually gain you power.

i did a bunch of different Damper tests for Troy Coughlin's (Jegs) NHRA ProStocker in 1994
ATI , Rattler, Fluid Damper, etc.

and then i personally did a bunch on various engines i had in my Shop -vs- no Damper

you will always loose TQ and HP if you run without a Damper
ATI Damper always beat out the other Dampers i tested thru the years !

i put all that Data info into equation form in PipeMax v4.50
so you can instantly see how much TQ and HP a Damper or without a Damper can give you

Edit : i forgot about Innovators West Dampers ... these Dampers were neck-and-neck HP results as ATI Damper in Dyno tests on NHRA SuperStockers

[RDY4WAR]

That's actually surprising. I did a smaller damper on a 347ci SBF making 485 rwhp, and it picked up a few hp on the same dyno. Talking ~1%.

WoO Sprints don't run a damper either.

Coincidentally, Engine Masters released an episode on Motor Trend this morning on this very subject. They ran with a heavy damper and without, same with the flywheel, ran at 300 rpm/sec and 600 rpm/sec, and found a good bit of power with less rotating mass.

[maxracesoftware]

That's actually surprising. I did a smaller damper on a 347ci SBF making 485 rwhp, and it picked up a few hp on the same dyno. Talking ~1%.

WoO Sprints don't run a damper either.

Coincidentally, Engine Masters released an episode on Motor Trend this morning on this very subject. They ran with a heavy damper and without, same with the flywheel, ran at 300 rpm/sec and 600 rpm/sec, and found a good bit of power with less rotating mass.

can you Post the Link ( Engine Masters released an episode on Motor Trend this morning on this very subject. )

[turbo camino]

I can't remember seeing a F1 engine with a dampener.

Does it still count if it doesn't look like something that belongs on a farm implement?

https://www.f1technical.net/forum/viewt ... =4&t=26642

[Ken_Parkman]

A damper is a sophisticated and engineered device designed to control torsional vibrations, which are a result of the firing impulses acting on the crank. The crank has natural frequencies in it affected by stiffness and the mass of items, and the firing pulses act in combinations called exciting orders which are in 1/2 rpm increments of the rpm up to something like 10. Some exciting orders are more critical than others depending on how they all add up. It is also interesting that some orders are worse at low power due to the vacuum on that cycle.

Somewhere during the operation of the engine in all of that mess you will find an rpm where an exciting order will line up with a crankshaft mode, and you get a vibration excitation and resonance where the crank snout is vibrating back and forth and the amplitude can be in degrees. This is astonishingly destructive and breaks stuff along with wreaking havoc with things like cams and ignition. I figure the first sign of a badly designed damper is the timing chain beat to hell. BTW in my opinion a timing belt does nothing for damping, but is able to withstand the abuse of a bad damper better.

Less stiff cranks, longer cranks with more throws, and heavier components push the natural frequencies down. Higher rpms make the likelihood of resonances more likely. Sustained operation in a resonance is likely to bust stuff; beware of steady state high rpm with a poorly designed damper.

A stiff short crank in a low rpm engine is a lot less likely to have problems.

I would NEVER operate an engine without a damper if it is designed for one, but maybe I am conservative. Of course you will always find a story where it has been done successfully.

As far as I am concerned most (not all) aftermarket damper manufacturers do not even know what a damper is, let alone how to design one. It's a crapshoot.

[4vpc]

the right dampener will actually gain you power.

i did a bunch of different Damper tests for Troy Coughlin's (Jegs) NHRA ProStocker in 1994
ATI , Rattler, Fluid Damper, etc.

and then i personally did a bunch on various engines i had in my Shop -vs- no Damper

you will always loose TQ and HP if you run without a Damper
ATI Damper always beat out the other Dampers i tested thru the years !

i put all that Data info into equation form in PipeMax v4.50
so you can instantly see how much TQ and HP a Damper or without a Damper can give you

Edit : i forgot about Innovators West Dampers ... these Dampers were neck-and-neck HP results as ATI Damper in Dyno tests on NHRA SuperStockers

Did you ever test an I4? If so what was the outcome?

[maxracesoftware]

long ago, when NHRA first came out with Damper specs + requirements
Solid Aluminum Hub/Dampers became popular mostly because they were cheap alternative to beat new Rules
can't really call it a Damper

i ran a very small diameter red anodized Moroso Solid Aluminum Hub/Damper on my 3.250" Stroke C/ED 316cid Engine
trick John Lingenfelter C/ED steel pan ,5.67 rear gears , crossed 10000+ RPM every pass
still have the Pan + the Solid Aluminum Hub ... and a much larger heavier ATI Balancer was worth more HP on this engine in Dyno tests

i saw a few BigBlock Chevy engine from various Engine Builders thru the years
that used these Moroso Solid Hubs have Crank snouts break right-off ... mostly were main bearing failures + cracked cranks .

Craig's Record setting A/ND and B/ND engines use just a solid Hub
reason : no way to run a real Damper because of all the front-driven drives Magneto,etc
Craig wants to run a ATI Damper , but can't fit it in

One time , on my SF-901 with the old 1000 Lbs Brake/Absorber
we made 4 or 5 Dyno tests ...everything was great ... then next Dyno test ,
the 2 bolts that hold the Strain-Gauge started backing out from engine vibrations + HP was down too
i told Craig , the Crank might have just cracked
i'd go back after each Pull and retighten those 2 bolts ... made 4 or 5 more pulls , bolts kept loosening + HP was down a little
Craig decided to run it in Houston ... 2nd or 3rd Run it killed all the main bearings

Craig brought me the Crank after he had it magnufluxed ... said it didn't look cracked ??
i stood the Crank on it end ... hit the top counterweights with a Hammer ... very dull thud ... no ringing
flip it over on its snout ... hit the other counterweights with a Hammer ... again , very dull thud ... no ringing

i went get my stock GM OEM steel 3.480" crank i ran in my 355cid 725HP @9000 RPM 10000 RPM thru MPH lights
i hit counterweights with Hammer ... beautifull long ringing tone

i told Craig , next time try hitting counterweight to verify crank is cracked + the magnafluxing