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Automotive Powered Off Road (AKA: Buggys, Jeeps, Trucks, Etc,Etc. ) => Motor and Drivetrain => Topic started by: fabr on November 04, 2019, 05:26:13 PM

Title: Detonation Detection
Post by: fabr on November 04, 2019, 05:26:13 PM
VERY interesting info for anyone tuning.

https://www.yellowbullet.com/forum/showthread.php?t=533112&highlight=FAST+vacuum+sensor
Title: Re: Detonation Detection
Post by: fabr on November 04, 2019, 06:20:34 PM
This is good also. First 20 or so posts anyway.

https://www.yellowbullet.com/forum/showthread.php?t=342893&highlight=FAST+vacuum+sensor

Title: Re: Detonation Detection
Post by: fabr on November 04, 2019, 06:46:28 PM
A lot of these posts have concerned NOS use and tuning but they still apply whether N/A,NOS or boosted.

I never knew any of this and find it really interesting on how to detect tuning induced detonation in short order.

SOOOoooo,here's another.

https://www.yellowbullet.com/forum/showthread.php?t=342893&highlight=FAST+vacuum+sensor
Title: Re: Detonation Detection
Post by: dsrace on November 05, 2019, 03:50:57 PM
thanks for sharing that !!   i will have to sit down on the computer and re read all of that again. i see those posts are 7 years old but good info. one of the posters said something to the effect of.....proper timing and afr can be seen......so i would like to see that part expanded on.
Title: Re: Detonation Detection
Post by: fabr on November 05, 2019, 06:36:17 PM

Yellow bullet has ,IMO,the absolute best forum info there is. LOTS of info you will not see anywhere else.

.proper timing and afr can be seen..

Bottom line is that detonation and too rich can be seen as loss of ring seal/loss of crankcase vacuum. Of course none of that info means a thing to those not running vac pumps or 3-4 or more scavenge stage dry sumps.

What got me to looking deeper into this is the old nascar SB2.2 I'm running. It had a 4 stage pump on it and no vac regulator on a sealed engine. No venting at all yet it had zero evidence of any oil leaks anywhere. Got to asking and it seems the engines drive the pump at a speed that at 9300 rpm is just right for the blowby to be perfectly balanced so as to provide around 20" vac.  Cool. Then I ran across this interesting stuff about tuning with crankcase vac readings. I guess it's not really tuning as much as being able to see the engine is happy/not happy with the tune .
Title: Re: Detonation Detection
Post by: fabr on November 05, 2019, 06:44:53 PM
As a side note,I am going to shelve my 3 stage pump and going to a 5 stage to be able to not run valve stem seals as can be done with 10-15" crankcase vacuum -with the now known added bonus of detecting detonation . COOL! Since I will not be running at a constant rpm I will use a vacuum regulator in one valve cover and a one way vent in the other.

Not running valve stem seals is said to allow ample lube of the skinny titanium valve stems so as to not risk galling while keeping excess oil from entering cylinder. They say with right crankcase vac it is better than stem seals in dealing with oil control.
Title: Re: Detonation Detection
Post by: dsrace on November 06, 2019, 08:29:08 AM

Yellow bullet has ,IMO,the absolute best forum info there is. LOTS of info you will not see anywhere else.

.proper timing and afr can be seen..

Bottom line is that detonation and too rich can be seen as loss of ring seal/loss of crankcase vacuum. Of course none of that info means a thing to those not running vac pumps or 3-4 or more scavenge stage dry sumps.

What got me to looking deeper into this is the old nascar SB2.2 I'm running. It had a 4 stage pump on it and no vac regulator on a sealed engine. No venting at all yet it had zero evidence of any oil leaks anywhere. Got to asking and it seems the engines drive the pump at a speed that at 9300 rpm is just right for the blowby to be perfectly balanced so as to provide around 20" vac.  Cool. Then I ran across this interesting stuff about tuning with crankcase vac readings. I guess it's not really tuning as much as being able to see the engine is happy/not happy with the tune .


reading through it last night i was starting to get the idea this type crank case checking required a vac pump.   still info i have never heard before! good info worth the read even for those that aren't using pumps on the ccv.
Title: Re: Detonation Detection
Post by: fabr on November 06, 2019, 08:35:51 AM
A vac pump will increase hp. It's worth the cost. If I wasn't running dry sump I would have a vac pump.
Title: Re: Detonation Detection
Post by: dsrace on November 06, 2019, 03:54:02 PM
so i know it's not the same thing exactly and i am not dry sumped but i do have a ccv catch can that does have a hose connected pre turbo in the air cleaner housing. there is slight vac on that ccv catch can that way. it is enough that i do not see any steam or such  come out of the pod filter at the top of the catch can. no steam at idle and of course i cannot tell at speed.
Title: Re: Detonation Detection
Post by: fabr on November 06, 2019, 07:04:36 PM
I'd be surprised if there was even .5 inches of vac from that. Not enough to have any effect other than pulling some vapors away.

Crankcase vac of 8-10 inches will definitely free up horsepower from increased ring seal. This is a proven fact on any engine.15 inches is about the limit on hp increases until over somewhere around 7500rpm. At that point on up hp will continue to increase until around 23 inches or so . Further hp increases are realized when a low ,low tension ring package is used . WHen using such ring packages crankcase vac is a must. I got to worrying that my 3 stage dry sump would not be able to reach enough vac and that is why I'm going to a 5 stage with vac regulation.
Title: Re: Detonation Detection
Post by: dsrace on November 07, 2019, 03:24:51 PM
wonder what would be recomended with forced induction?
Title: Re: Detonation Detection
Post by: fabr on November 07, 2019, 05:50:14 PM
Same. NOS,N/A,boosted. Ring seal is ring seal. Low leak down is key.Just need a vac pump or enough dry sump stages to get the amount of vac desired or needed as dictated by the ring package. Loss of ring seal from detonation is what is trying to be avoided.