Speed-Talk is running on www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

NA Engine With No Damper?

General engine tech -- Drag Racing to Circle Track

Moderator: Team

RDY4WAR
Member
Member
Posts: 111
Joined: Tue Jun 20, 2017 12:58 am
Location:

NA Engine With No Damper?

Post by 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
Guru
Guru
Posts: 9841
Joined: Thu Mar 04, 2010 8:05 pm
Location:

Re: NA Engine With No Damper?

Post by 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
Last edited by pdq67 on Fri Sep 25, 2020 1:38 pm, edited 1 time in total.
bthomas
New Member
New Member
Posts: 16
Joined: Fri Jul 31, 2020 10:43 pm
Location:

Re: NA Engine With No Damper?

Post by bthomas »

Iirc vizard did tests on this topic, and no damper lost power. Actually going to bigger damper increased power.
Last edited by bthomas on Fri Sep 25, 2020 1:37 pm, edited 1 time in total.
bthomas
New Member
New Member
Posts: 16
Joined: Fri Jul 31, 2020 10:43 pm
Location:

Re: NA Engine With No Damper?

Post by bthomas »

Firechicken
New Member
New Member
Posts: 19
Joined: Sun Jan 26, 2020 10:32 am
Location: BC Canada

Re: NA Engine With No Damper?

Post by Firechicken »

Some Pontiac V8 engines in the 70s were factory built with just a hub but they only revved to about 4500.
BlitzA64
HotPass
HotPass
Posts: 713
Joined: Sun Feb 28, 2010 8:49 pm
Location:

Re: NA Engine With No Damper?

Post by 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.
GLHS60
Guru
Guru
Posts: 1153
Joined: Fri Oct 15, 2010 1:55 am
Location: Sherwood Park, Alberta, Canada

Re: NA Engine With No Damper?

Post by GLHS60 »

Timing belt seems sufficient on some OHC 4 cylinder Engines?

Thanks
Randy
RDY4WAR wrote: Fri Sep 25, 2020 1:00 pm
Could a 6-rib serpentine belt provide some absorption of harmonics?
Sherwood Park
Alberta,Canada
There is no logical reason to call an Engine a motor.
frnkeore
Pro
Pro
Posts: 300
Joined: Wed Dec 25, 2019 3:06 am
Location: Oregon

Re: NA Engine With No Damper?

Post by frnkeore »

I can't remember seeing a F1 engine with a dampener.
lefty o
Guru
Guru
Posts: 3069
Joined: Tue Oct 15, 2013 8:50 am
Location:

Re: NA Engine With No Damper?

Post by lefty o »

the right dampener will actually gain you power.
maxracesoftware
Vendor
Posts: 3008
Joined: Sat Feb 14, 2004 4:04 pm
Location: Abbeville, LA
Contact:

Re: NA Engine With No Damper?

Post by maxracesoftware »

lefty o wrote: Fri Sep 25, 2020 3:00 pm 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
MaxRace Software
PipeMax and ET_Analyst for DragRacers
http://www.maxracesoftwares.com
PipeMax v4.50 Download Link : http://www.mediafire.com/file/4x3fwqub0 ... 0.zip/file
RDY4WAR
Member
Member
Posts: 111
Joined: Tue Jun 20, 2017 12:58 am
Location:

Re: NA Engine With No Damper?

Post by 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
Vendor
Posts: 3008
Joined: Sat Feb 14, 2004 4:04 pm
Location: Abbeville, LA
Contact:

Re: NA Engine With No Damper?

Post by maxracesoftware »

RDY4WAR wrote: Fri Sep 25, 2020 3:38 pm 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. )
MaxRace Software
PipeMax and ET_Analyst for DragRacers
http://www.maxracesoftwares.com
PipeMax v4.50 Download Link : http://www.mediafire.com/file/4x3fwqub0 ... 0.zip/file
turbo camino
Pro
Pro
Posts: 383
Joined: Sun Aug 10, 2008 11:51 am
Location:

Re: NA Engine With No Damper?

Post by turbo camino »

frnkeore wrote: Fri Sep 25, 2020 2:59 pm 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
DON'T PANIC
Ken_Parkman
Expert
Expert
Posts: 550
Joined: Sun Jan 02, 2005 11:30 pm
Location: Ontario, Canada

Re: NA Engine With No Damper?

Post by 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
Pro
Pro
Posts: 330
Joined: Thu Jan 21, 2016 6:26 pm
Location:

Re: NA Engine With No Damper?

Post by 4vpc »

maxracesoftware wrote: Fri Sep 25, 2020 3:25 pm
lefty o wrote: Fri Sep 25, 2020 3:00 pm 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?
There is no S on the end of RPM.
Post Reply