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128 my take, anybody see it like this ?

General engine tech -- Drag Racing to Circle Track

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hoffman900
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Re: 128 my take, anybody see it like this ?

Post by hoffman900 »

F-BIRD'88 wrote: Wed Sep 21, 2022 3:04 pm
Orr89rocz wrote: Wed Sep 21, 2022 2:17 pm
F-BIRD'88 wrote: Wed Sep 21, 2022 10:33 am


When you read DV's books and select the overlap as per the overlap pie chart for the intended application RPM and build level. and apply the 128 formula for that engine you get a camshaft duration. (within a workable relevent range)
Mostly biased for a single pattern camshaft.

You can then tweek things a bit if you want a dual pattern cam. This tends to widen the LSA a hair. It doesn't have to but...- it tends to-. And then you can tweek the installed position "advance" .. Don't be timid to play with this +/-.
And as DV said in his comments a Dual Plane intake manifold can tolerate a slight widening of the LSA a hair. VS what a single plane manifold is going to favour to make good torque.

It is intended as a guide for the end user to get a high torque per cid street strip perf engine.
A better but simple method VS just selecting from the catalog page.
It’s unfortunate the catalog cams never seem to come in under 110 lsa. Can find some under that but much more limited than the 110-114 lsa cams out there. So sucks the program gives you 104-108 lsa stuff and you still have to get it custom ground if there are cores available for that tight lobe separation

There are lots of catalog cams that are 104 105 and 106 and 108 LSA.. You just have to look.
Check out the Isky cams stuff. These cams ALWAYS work well.

Check out the Linati / UDHAROLD "Street/Strip" cams series and the tight lash stuff.
Most of those are directed at circle track and road racers, which centerlines in those areas work great for. They are not very efficient under 3000rpm though.

Like I have said. Vizard’s formula isn’t doing anything special. He data fit results of engines he tested on the dyno to make good torque / ci for those applications. The problem is there is more to a cam than dyno results and no one on the street needs best power between 3500-7000rpm at WOT.
-Bob
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

hoffman900 wrote: Wed Sep 21, 2022 3:02 pm
skinny z wrote: Wed Sep 21, 2022 2:50 pm
hoffman900 wrote: Wed Sep 21, 2022 2:43 pm A cam with durations around 260* at .050” + and ground 104-106 (straight up) is going to be too much for a lot of those people.
How about 234 @ .050" on a 108 and a 104 ICL? :wink:
Have no idea. How much lift? And if it’s a bunch, how are you planning on keeping that together.

There are a lot of street set ups out there with aggressive lobes / valve lift profiles that would self destruct pretty quickly if they spent any amount of time at higher rpm’s. Stuff like that is the reason Car Craft would make 450hp with a $4000 build (just had to last long enough to make the pull for the article) but to do the same and make it live for 3000 miles in racing would be a $20k + engine.
All valid points and something I am taking into consideration.
I only posted that spec as my example on going for overlap value (which worked well for me in a similar build), then applying the 128 rule (which I've never used) and ultimately Torque Master.
Torque Master doesn't offer an .050" number. Only seat duration.
This, as you've pointed out, is where the decision has to be made regarding how aggressive to get. Is it 280 adv and 234@.050" or 280 and 220@.050".
Kevin
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

hoffman900 wrote: Wed Sep 21, 2022 3:06 pm Like I have said. Vizard’s formula isn’t doing anything special. He data fit results of engines he tested on the dyno to make good torque / ci for those applications. The problem is there is more to a cam than dyno results and no one on the street needs best power between 3500-7000rpm at WOT.
But if output is sought between converter stall speed and RPM at the stripe then it should have some value.
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Re: 128 my take, anybody see it like this ?

Post by F-BIRD'88 »

You see a lot of the street hyd roller cams on a 112 LSA.
Thats because the average guy who looks for these wants a no hassle no set up cam as far as how it idles and drives at low speed..
They will get all pissy with a 106 LSA hyd roller cam.
Modt refuse to tune for it nor select aproprate gears and converter for the car.
They get a warm fuzxy feeling with their new cam and the Cam companies Phone does not ring off the hook.

Comp will grind what ever you want at the catalog cam price as long as it does not require a custom cam core.
They will ship to Summit or your local Speed shop dealer or to your house.. You just have to pick up the phone and ask.
Its not that hard.

Hyd roller cams tend to have a few degrees more seat to seat duration VS the .,050" "shoe size"
Compared to a hyd flat tappet.
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Re: 128 my take, anybody see it like this ?

Post by hoffman900 »

skinny z wrote: Wed Sep 21, 2022 3:12 pm
hoffman900 wrote: Wed Sep 21, 2022 3:06 pm Like I have said. Vizard’s formula isn’t doing anything special. He data fit results of engines he tested on the dyno to make good torque / ci for those applications. The problem is there is more to a cam than dyno results and no one on the street needs best power between 3500-7000rpm at WOT.
But if output is sought between converter stall speed and RPM at the stripe then it should have some value.
Yeah, I mean that’s fair, but if you ran 5 x 12” passes that day and drove the car a total 3 hours (to, from, around to the track), that’s only .5% of total drive time. Have to pick your battles.

I’m also a road race type guy, so for me, whenever I see automatics in a performance application, I ask “why?”. Manuals are so much more fun for a toy, so can’t say I really ever think of in terms of converters.
-Bob
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

hoffman900 wrote: Wed Sep 21, 2022 3:21 pm. Have to pick your battles.
True that. And a decision I'm presently trying to work through.
Luckily for me, I'm 20 minutes from the track. All highway.

As for automatics, it's easier on parts at my level of drag racing.
I can't say the same for any open road event though.
Kevin
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Re: 128 my take, anybody see it like this ?

Post by juuhanaa »

skinny z wrote: Wed Sep 21, 2022 3:02 pm
juuhanaa wrote: Wed Sep 21, 2022 2:53 pm hmmmm


307 601.png
12:1 is outside of the operating parameters of the 128 rule.
LSA will widen according to the 128 rule and on which TM is based.
Do the same specs with 10.5:1 and post up.
307 601 10.5CR.png

I reduced CR to 10.5 and i did the calculus based on my new input Peak Power RPM which match the previous DCR. Now the program output 108 LCA, but its also 108hp down :D

I like all the parameters for 12CR. I dont know is it doable using 305 iron heads, flat top pistons and .43lift roller cam with 196int duration at 050 inch lift.
You do not have the required permissions to view the files attached to this post.
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

juuhanaa wrote: Wed Sep 21, 2022 4:36 pm
skinny z wrote: Wed Sep 21, 2022 3:02 pm
juuhanaa wrote: Wed Sep 21, 2022 2:53 pm hmmmm


307 601.png
12:1 is outside of the operating parameters of the 128 rule.
LSA will widen according to the 128 rule and on which TM is based.
Do the same specs with 10.5:1 and post up.
307 601 10.5CR.png


I reduced CR to 10.5 and i did the calculus based on my new input Peak Power RPM which match the previous DCR. Now the program output 108 LCA, but its also 108hp down :D

I like all the parameters for 12CR. I dont know is it doable using 305 iron heads, flat top pistons and .43lift roller cam with 196int duration at 050 inch lift.
Compression is king.
As for your 12:1 and 196@.050"...
I would imagine the cranking cylinder pressure would be through the roof with a 104 ICL.
Kevin
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Re: 128 my take, anybody see it like this ?

Post by juuhanaa »

skinny z wrote: Wed Sep 21, 2022 5:07 pm
juuhanaa wrote: Wed Sep 21, 2022 4:36 pm
skinny z wrote: Wed Sep 21, 2022 3:02 pm

12:1 is outside of the operating parameters of the 128 rule.
LSA will widen according to the 128 rule and on which TM is based.
Do the same specs with 10.5:1 and post up.
307 601 10.5CR.png


I reduced CR to 10.5 and i did the calculus based on my new input Peak Power RPM which match the previous DCR. Now the program output 108 LCA, but its also 108hp down :D

I like all the parameters for 12CR. I dont know is it doable using 305 iron heads, flat top pistons and .43lift roller cam with 196int duration at 050 inch lift.
Compression is king.
As for your 12:1 and 196@.050"...
I would imagine the cranking cylinder pressure would be through the roof with a 104 ICL.
Its also 288int duration at seat and maybe close enough what the program recommend. Truck cam to move some bricks :)

Chevrolet Performance Hydraulic Roller Camshafts 14097395
A balanced person dares to stagger, and modify ports bigger
skinny z
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

Looks like an old Lingenfelter profile. Its very similar to the GM cam.
Crazy slow. Not sure what the IVC is but I'm thinking it's such that it'll bleed off some of that compression.
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Re: 128 my take, anybody see it like this ?

Post by Tartilla »

hoffman900 wrote: Mon Sep 19, 2022 9:08 pm
digger wrote: Mon Sep 19, 2022 8:48 pm
CamKing wrote: Mon Sep 19, 2022 9:59 am If it 's accurate for a Chevy, but not a Ford, it's not a formula, it's a rule of thumb.
If it's accurate for a Small Block, but not a Big Block, it's not a formula, it's a rule of thumb.
If it's accurate for a 350cid SB, but not for a 406cid SB, it's not a formula, it's a rule of thumb.
There is nothing that says a formula must be accurate in order to be classified as a formula. It’s just very very far from universal.

Newtons laws probably don’t work accurately inside a black hole or at a quantum level.

I find the formula interesting in the trend it implies.
I get hung up on how people have given great engineering / science based principals, backed up with empirical evidence, on a number of topics here, ans get glossed over for rules of thumb and other folklore that just won’t go away.

It reminds me of a racing friend / engine builder who won a lot about when I asked him why he doesn’t keep secrets “because they won’t listen to me and misconstrue what I say even though I’m beating them”
During WW2, the Germans were having reliability issues with their aero engine bearings. They captured American aircraft to analyze their bearings to determine why the Yanks had better bearing longevity. Turns out, the Germans dismissed the key element, as a contaminant.

As for a formula, I would say that it all comes down to what is being asked for a solution. In the 128 formula, the extrapolated solution is to solve the lack of flow through the heads with respect to the CID. Hence the primary factor is a 2 vs 4 valve head.

The 128 number, is just a constant for a larger formula, that has many '128' numbers, depending on your individual parameters.

The greater solution, is enabling enthusiasts to get a good cam for their needs, with less compromise. Teach them to fish.
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

Tartilla wrote: Wed Sep 21, 2022 9:14 pm The 128 number, is just a constant for a larger formula, that has many '128' numbers, depending on your individual parameters.
The author has said as much as they are different "qualifiers" for changes in compression ratio, intake valve size (which is really just an easy way to define an average CoD), CID, etc.
IIRC, the 128 is modified to suit the canted valve BBC but I can't say what that number is.
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Re: 128 my take, anybody see it like this ?

Post by Orr89rocz »

hoffman900 wrote: Wed Sep 21, 2022 3:06 pm
F-BIRD'88 wrote: Wed Sep 21, 2022 3:04 pm
Orr89rocz wrote: Wed Sep 21, 2022 2:17 pm

It’s unfortunate the catalog cams never seem to come in under 110 lsa. Can find some under that but much more limited than the 110-114 lsa cams out there. So sucks the program gives you 104-108 lsa stuff and you still have to get it custom ground if there are cores available for that tight lobe separation

There are lots of catalog cams that are 104 105 and 106 and 108 LSA.. You just have to look.
Check out the Isky cams stuff. These cams ALWAYS work well.

Check out the Linati / UDHAROLD "Street/Strip" cams series and the tight lash stuff.
Most of those are directed at circle track and road racers, which centerlines in those areas work great for. They are not very efficient under 3000rpm though.

Like I have said. Vizard’s formula isn’t doing anything special. He data fit results of engines he tested on the dyno to make good torque / ci for those applications. The problem is there is more to a cam than dyno results and no one on the street needs best power between 3500-7000rpm at WOT.
I honestly think thats the perfect power band. 3500 stall and 3500-7000. Thats how my 383 efi street motor was set up, and alot of cammed cars i have tuned. 3000-6500 ish.

Based on gearing and auto electronic trans control there is no way to be wot under 3000 it seems. Maybe some of the tpi 80’s gm motors i played with who peak at 4500 but still have 2500-2800 stall speeds, wot from there on up.
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Re: 128 my take, anybody see it like this ?

Post by rebelyell »

In the larger view, it seems "128" is applicable to only a very narrow range of strictly defined applications. I'd hoped for more.
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Re: 128 my take, anybody see it like this ?

Post by skinny z »

Orr89rocz wrote: Wed Sep 21, 2022 9:34 pm
hoffman900 wrote: Wed Sep 21, 2022 3:06 pm
F-BIRD'88 wrote: Wed Sep 21, 2022 3:04 pm


There are lots of catalog cams that are 104 105 and 106 and 108 LSA.. You just have to look.
Check out the Isky cams stuff. These cams ALWAYS work well.

Check out the Linati / UDHAROLD "Street/Strip" cams series and the tight lash stuff.
Most of those are directed at circle track and road racers, which centerlines in those areas work great for. They are not very efficient under 3000rpm though.

Like I have said. Vizard’s formula isn’t doing anything special. He data fit results of engines he tested on the dyno to make good torque / ci for those applications. The problem is there is more to a cam than dyno results and no one on the street needs best power between 3500-7000rpm at WOT.
I honestly think thats the perfect power band. 3500 stall and 3500-7000. Thats how my 383 efi street motor was set up, and alot of cammed cars i have tuned. 3000-6500 ish.

Based on gearing and auto electronic trans control there is no way to be wot under 3000 it seems. Maybe some of the tpi 80’s gm motors i played with who peak at 4500 but still have 2500-2800 stall speeds, wot from there on up.
Further to that, I can say that a cam selected to operate in that RPM window of 3500-6500(+/-) will still be workable on the street. You can do a lot with 70+ degrees of seat timing overlap. And I found that amount to work well and still manage some decent fuel economy on the highway with a 3500 stall lockup converter and overdrive. (Decent being 20+ USMPG steady state highway carbureted).
Kevin
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