The 128 drama!

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Re: The 128 drama!

Post by David Vizard »

Digger,

I put value to your post contents so could I ask you to elaborate on this as it could help me explain my procedures better.

this seems to agree with David’s work about the LSA being “fixed” (not that I agree with the methodology put forward as i would have separated out ICL and ECl and looked for trends in those separately rather than LSA with more time)

thanks
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Re: The 128 drama!

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ptuomov wrote: Mon Jan 06, 2020 7:16 pm There’s a Ford paper on restricted intake engines. Compared to unrestricted intake engines, the overlap remained almost the same but exhaust duration had to be reduced a lot and intake duration less. Would this mean that restricted intake would call for a tighter LSA?
is anyone interested in a piece on how do make the most of cam and valve train on a restricted motor?

If so I can pull data from my F3 days with 10,000 rpm restricted 61 inch engines.
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Re: The 128 drama!

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GARY C wrote: Tue Jan 07, 2020 12:46 am
digger wrote: Mon Jan 06, 2020 10:40 pm I don’t think the port size has much to do with idle (other than low lift curtain area ) it’s mostly the overlap and associated curtain area , cylinder size and cross talking which is not the same as looking at LSA saying it will idle poorly . Small duration and 100LSA can idle fine, the same IR will tolerate More overlap
What cam does an F1 engine run that causes it to idel at 7000 rpm?

I am sure the cam plays a part but I ran the same cam, heads intake and carb on a 306, 357, 379 and 382 and less idle speed was needed as the displacement went up, all things equal the 306 was around a second slower naturally aspirated and would bog slightly at a 7500 rpm shift.

I later changed the cam 10 degrees less and 8 degrees wider to dyno the 357 on nitrous, it did nothing for the idle quality and without the nitrous the tq was shitty to say the least.

It just seems less displacement requires more rpm to overcome reversion, or a really late opening small cam to bandaid it.
Gary, Ref What cam does an F1 engine run that causes it to idle at 7000 rpm?

Low mass/moment of inertia of internals and crank don't help the idle. With a 100 lb flywheel you can get a cup car to idle at 300 rpm!
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Re: The 128 drama!

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Hoffman 900 wrote:-

It's a forced equation for camshaft LSA on a 10:1, 350ci, street engine, that maximizes torque but may inhibit drive ability. Furthermore, some of this equation runs in conflict to things Harold Brookshire and Mike Jones have shared here. They may not have written books, but they designed camshafts that have produced championships on the professional level.

Is this Speedtalk where we are trying to learn how engines work and make them better or produce cookie cutter engines that you can find in the pages of all those defunct TEN magazines?

David has his own subforum for promotion.


Bob,
Let me address your comments one at a time here. First :-
It's a forced equation(??? what the heck is that???? ) for camshaft LSA on a 10:1, 350ci, street engine, No, it can apply to any 10.5/1 SB chevy and can target peak power rpm from 4500 to 9000 or what-ever should you choose to build a race engine with 10.5/1. that maximizes torque And power but may inhibit drive ability. Unless the tune up is poor why would an optimal cam have poor drivability???


Furthermore, some of this equation runs in conflict to things Harold Brookshire and Mike Jones have shared here. I have great respect for both these gentlemen but I seriously doubt that their combined cam dyno testing experience is even close to what I have done. They may not have written books, but they designed camshafts that have produced championships on the professional level.

I suspect that many think because I write books that it somehow precludes me from winning races or championships. Would it be possible here to get some credit for winning 4 championships by winning every single race. How about 26 wins in the British Touring Car Championship for two championship wins at international level. Those cars had my head work my carbs ( at a carb dyno shootout at the factory they were 6 hp better than Weber's engineers could come up with and I told them that would be the case beforehand. Obviously they somehow thought this was a joke as afterall I wrote books!! My best year as an engine builder scored a combined 169 pole positions fastest laps track records wins and 5 championship wins. Would thousands of hours of cam testing for some of the biggest names in the cam business and all these race wins etc possibly qualify me to do cam recommendations that contradict so many with less experience than I - in spite of the fact I write books and articles?

Is this Speedtalk where we are trying to learn how engines work I am just passing on the results of hundreds of thousands dollars worth of cam testing so ST members can learn to better their cam selection skills. Remember buying the wrong cam costs just as much as buying the right one. What I feel I am doing here is not only informing ST posters based on very extensive experience in the field but also saving them both disappointment and money. and make them better or produce cookie cutter engines Tell me - which is best - to have a motor build dreamt up by a averagely informed engine builder making say 450 hp (if they are lucky) for $4000 or one specced out by a championship winning engine builder thus possibly qualifying it as a 'cookie cutter' build, for the same $4000 but making 500 hp. that you can find in the pages of all those defunct TEN magazines? At a guess these magazines did not help their circulation figures because those so called 'cookie cutter' builds were not that special. One of the most sought after articles for reprint is the 350 Sledge Hammer budget build published in Pop Hot rodding. If anyone cares to find this and post it I would gladly tell the story behind the story on the cam selection.

David has his own subforum for promotion.

Bob, we are on my 'subforum' now" And what am I promoting here? I will make that clear. What I am 'promoting' is some very useful and very FREE high dollar info that will be of great use to those who care to apply it.

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Re: The 128 drama!

Post by Stan Weiss »

Small-Block Engine Build - Son Of Sledgehammer
Enginequest's New 23-Degree Iron Heads Break New Bang-For-The-Buck Ground: We Built A 470hp Small-Block For Just $3,075, And You Can Too.

https://www.hotrod.com/articles/0710phr ... ine-build/


Budget Engine Build - Tough Act To Follow
Can we top the horsepower-per-dollar result of our Budget Sledgehammer Vortec? We came close with T&L's small-block 383 crate stroker, and saved a bunch of trouble.

https://www.hotrod.com/articles/0703phr ... ine-build/

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Re: The 128 drama!

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Stan Weiss wrote: Wed Jan 08, 2020 6:24 pm Small-Block Engine Build - Son Of Sledgehammer
Enginequest's New 23-Degree Iron Heads Break New Bang-For-The-Buck Ground: We Built A 470hp Small-Block For Just $3,075, And You Can Too.

https://www.hotrod.com/articles/0710phr ... ine-build/


Budget Engine Build - Tough Act To Follow
Can we top the horsepower-per-dollar result of our Budget Sledgehammer Vortec? We came close with T&L's small-block 383 crate stroker, and saved a bunch of trouble.

https://www.hotrod.com/articles/0703phr ... ine-build/

Stan
Stan,
Neither of these is the original 'sledgehammer' build which came a year or so earlier.
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Re: The 128 drama!

Post by Stan Weiss »

David,
My Bad! I forgot that you did not write the original article

447 HP Vortec Small-Block Build – Budget Sledgehammer
Written by Johnny Hunkins on September 22, 2006
Steve Dulcich - writer;

https://www.hotrod.com/articles/0611em- ... all-block/

Stan
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Re: The 128 drama!

Post by GARY C »

I found the 600 HP 396 to be an interesting build although I am not brave enough to grind on a perfectly good 350 block. :)
http://www.superchevy.com/how-to/engine ... all-block/
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Re: The 128 drama!

Post by digger »

David Vizard wrote:
> Digger,
>
> I put value to your post contents so could I ask you to elaborate on this
> as it could help me explain my procedures better.
>
> [b][i][color=#0000FF]this seems to agree with David’s work about the LSA
> being “fixed” (not that I agree with the methodology put forward as i would
> have separated out ICL and ECl and looked for trends in those separately
> rather than LSA with more time)[/color][/i][/b]
>
> thanks
> DV

David,

what i meant was that i would have looked for trends with ICL and ECL as separate variables. as the two are separate processes with only a partial overlap portion.

when i did the 1D sims the LSA = ICL = ECL. So i dont know if it was"

A)the LSA or
B) the ICL and / or the ECL

driving the trend.

regards
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Re: The 128 drama!

Post by skinny z »

Interesting that this particular subject should come up at this time. I had come across this article:

https://www.hotrod.com/articles/0703phr ... ine-build/

I'm considering using it as a template for a small runner (170cc RHS Pro Torker Vortec w/ pocket porting), 10:1, 383.
I've adopted the 128 rule as a guideline but it seems I'm entirely alone in that regard. Soliciting recommendations from a couple of respected cam suppliers (one of which is mentioned in this thread, no big box companies) as well as my internet brothers have yielded nothing with a 106 LSA (as would be specified by the 128 rule). Further to that, the recommendations are skewed towards the particular chassis this engine will go in whereas I'm looking for the best numbers overall (I can make the chassis fit the engine rather than the other way around although I fully understand the intent of the recommendations). I've had responses that address that and indeed the LSA did tighten up.
Having a predetermined LSA is all well and good but how does this relate to an engine such as the one in the aforementioned article? In particular, the combination in question is the 170cc Edelbrock headed version with the reduced compression ratio. For the record that CR was dialed in at 9.8:1. Considering that in my particular case with iron heads, 9.8:1 (from my experience anyway) is a very workable value. From the 128 article, a lower than specified 10.5:1 CR suggests that the LSA can be reduced even further. Does the smaller head (but given a typical discharge coefficient with a 2.02 intake valve and decent valve job) require a change in the application of the 128 spec? And how is the ICL affected by all of this? I can go further into this and also ask about dual pattern profiles. I will be targeting an open header with a calculated collector length in an attempt to reap the benefits of the expected exhaust scavenging. So single pattern or extended exhaust duration? (The heads in question have an intake to exhaust ratio of about 71%) How this plays out in full street trim is of less interest to me.
There are many nuances to consider and I'm hoping that I can have some light shed on this. I know going in that the overall results might be subtle and very dependant on the overall build but at this point it's become an exercise in what really will produce the best results from an engine point of view.
Thanks in advance.
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Re: The 128 drama!

Post by RevTheory »

Skinny,

A couple of points here: basically nobody you talk to is going to agree with David on running a 106 on the street. I went through this very thing years ago from local machine shops, the dyno operator I was going to, Comp's tech line, etc. They all say the same thing, "that'll never idle, you'll have no power until you get up there in rpm, totally wrong for the street, no torque" etc. You'll have to tow the line and stick to your guns. Don't ask the tech guy anything. Simply call and say, "I'd like to order this intake lobe, that exhaust lobe on a 106 +4. How would you like me to pay?"

I showed my dyno operator the cam card when I showed up and he said all of those things before it was even on the pump. A few hours later he gave the engine a full-throttle plug cut at 4,500 rpm, shut the engine off, looked at the screen while rubbing his head and said, "now what did you do with that cam? That would make a dynamite truck engine." Comp XE270, 227 @ .050, single-pattern, 107 LSA, 10:1, 383.

Point number 2 would be dealing with reversion. No matter how you slice it, if you run the duration that a 383 will need to rpm where you want it on a 106, you're going to have a pretty racy idle. It is what it is. I would recommend having a shop cut a 30* angle on the face of the intake valve. David briefly touches on it in, I believe, his cylinder head book circa early 90s. I'd also recommend sinking the exhaust valve .025". You'll likely have to argue with the machine shop about the validity of those moves but, like I said earlier, stick to your guns and kindly ask them to just humor you and do a quality job.

I wouldn't worry about making a small adjustment for being under 10.5:1

I hope that helps. David may chime in and slap me around soon, lol
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Re: The 128 drama!

Post by skinny z »

RevTheory wrote:
Skinny,

A couple of points here: basically nobody you talk to is going to agree with David on running a 106 on the street.

Point number 2 would be dealing with reversion. No matter how you slice
it, if you run the duration that a 383 will need to rpm where you want it
on a 106, you're going to have a pretty racy idle. It is what it is. I
would recommend having a shop cut a 30* angle on the face of the intake
valve. David briefly touches on it in, I believe, his cylinder head book
circa early 90s. I'd also recommend sinking the exhaust valve .025".
I wouldn't worry about making a small adjustment for being under 10.5:1

Thanks for the reply Rev
Yes. I'm getting exactly that although once I take the "street" out of the equation there is some acquiescence.
If only to be the one guy in the group that has done it and can post results would be worth it.
Regarding the 2nd point. I'd like to see peak power in or around 6000 (something I should have posted earlier). It's easier on parts and would also compliment the parts I have. Specifically the valvetrain. As for reversion, I've dealt with a carbed 355 that has 71 degrees of overlap. While not a lot necessarily, I've managed to tune it into compliance. My thinking is the same amount of overlap would put me in the rev range I'm looking for and tuning shouldn't be an issue.
The valve job is completed as I'm using the heads off of the 355. 30 degree back-cut included. I used that bit of info when building a Vortec 350 years back following DV'S advice given in his early edition of budget building SBC's.
Again thanks for the reply.
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Re: The 128 drama!

Post by ptuomov »

David Vizard wrote:
> is anyone interested in a piece on how do make the most of cam and valve
> train on a restricted motor?
>
> If so I can pull data from my F3 days with 10,000 rpm restricted 61 inch
> engines.
> DV

I think there are three fairly popular ways to restrict output in various racing classes:
(1) intake restrictor plate or spec carburetor
(2) max rpm limiter
(3) cast-iron exhaust manifolds required

It would be very interesting to understand how the camshaft needs to be changed (compared to the optimal cam for the unrestricted engine) when one of the three restrictions is imposed.
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Re: The 128 drama!

Post by GARY C »

skinny z wrote:
> RevTheory wrote:
> Skinny,
>
> A couple of points here: basically nobody you talk to is going to agree
> with David on running a 106 on the street.
>
> Point number 2 would be dealing with reversion. No matter how you slice
> it, if you run the duration that a 383 will need to rpm where you want it
> on a 106, you're going to have a pretty racy idle. It is what it is. I
> would recommend having a shop cut a 30* angle on the face of the intake
> valve. David briefly touches on it in, I believe, his cylinder head book
> circa early 90s. I'd also recommend sinking the exhaust valve .025".
> I wouldn't worry about making a small adjustment for being under 10.5:1
>
> Thanks for the reply Rev
> Yes. I'm getting exactly that although once I take the "street"
> out of the equation there is some acquiescence.
> If only to be the one guy in the group that has done it and can post
> results would be worth it.
> Regarding the 2nd point. I'd like to see peak power in or around 6000
> (something I should have posted earlier). It's easier on parts and would
> also compliment the parts I have. Specifically the valvetrain. As for
> reversion, I've dealt with a carbed 355 that has 71 degrees of overlap.
> While not a lot necessarily, I've managed to tune it into compliance. My
> thinking is the same amount of overlap would put me in the rev range I'm
> looking for and tuning shouldn't be an issue.
> The valve job is completed as I'm using the heads off of the 355. 30 degree
> back-cut included. I used that bit of info when building a Vortec 350 years
> back following DV'S advice given in his early edition of budget building
> SBC's.
> Again thanks for the reply.

I quit asking cam companys for recommendations in the late 90's after getting for drastically different recommendation from different tech guys at one cam company, they ranged from a 110 to a 114 LSA and 22 degrees difference in duration.

I have done around 8 different engines using cams in line with DV's writings and have been satisfied with the results.

The last was a 9.5:1 Pontiac 400 and my best calculation I was coming up around 106.5ish so rounded up to 107, I did fudge it a bit due to rocker ratio, Pontiac's 30 degree seat and the possibility of running a 50 shot of nitrous, so I settled on a Comp 268AH on a 108 LSA. around 55 or 56 degrees of overlap, I have about 195 cranking pressure, 14" of idle vac at 850 rpm, it's a 4spd with 3.42 gears and a 28" tall tire, it drives about like a fuel injected car.

I hope that helps.
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Re: The 128 drama!

Post by David Vizard »

Would it be safe to assume that some 128 doubters are coming around to the idea of the 128 (or what ever the engine types applicable number is) LCA selection method? If so, I could now start trying to convince doubters of the value of my 'so called' port energy.

I am still trying to figure out why it has been dubbed by certain factions as 'so called' port energy when in fact that is exactly what it is.

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