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Search found 1602 matches

by digger
Wed Sep 28, 2022 9:49 pm
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

At low and medium lifts the valve head is part of the Venturi but is not shown
by digger
Wed Sep 28, 2022 9:44 pm
Forum: Engine Tech
Topic: Camshaft lobe design by Billy Godbold
Replies: 48
Views: 1760

Re: Camshaft lobe design by Billy Godbold

Anyone that’s been on these forums a long while would not have learnt anything from this video as less tech in it than on threads here gone past. The target audience is the less technically minded.
by digger
Wed Sep 28, 2022 5:51 pm
Forum: Engine Tech
Topic: Camshaft lobe design
Replies: 122
Views: 41771

Re: Camshaft lobe design

Mike, I'm not measuring it, I'm calculating it, every 1/4 degree of piston movement. When I design a profile for an application, I input Bore, Stroke, Rod Length, Comp Ratio, Valve size, Choke diameter, Desired max HP RPM, and a few other things. You're using engine/port measurements to calculate t...
by digger
Wed Sep 28, 2022 5:33 pm
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

The Venturi shown is the valve seat by looks of the diagram , so looks like fairly normal port nothing new.

I think DM recommendation for max effort is for taper from port entry all the way to valve seat region. This isn’t achievable on many ports though
by digger
Thu Sep 22, 2022 4:50 am
Forum: Engine Tech
Topic: 128 my take, anybody see it like this ?
Replies: 158
Views: 4157

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

All methods for calculating cam specs are wrong, it’s just some are less wrong than others
by digger
Wed Sep 21, 2022 11:09 pm
Forum: Engine Tech
Topic: 128 my take, anybody see it like this ?
Replies: 158
Views: 4157

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

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 sep...
by digger
Tue Sep 20, 2022 5:23 pm
Forum: Engine Tech
Topic: 128 my take, anybody see it like this ?
Replies: 158
Views: 4157

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

I think this is also fundamental to the rule. Although, peak torque may be more of an emphasis. The average would fall into place. Of course, there are exceptions. I think the first thing people need to do is to create a histogram rpm plot on how they drive. We use 104-106 LSA (104/104 centerlines,...
by digger
Tue Sep 20, 2022 5:20 pm
Forum: Engine Tech
Topic: 128 my take, anybody see it like this ?
Replies: 158
Views: 4157

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

When i looked at this in ENGMOD4T this seemed to be reasonable provided you were only looking at WOT maximum average power in the 3-7k rpm range. I think this is also fundamental to the rule. Although, peak torque may be more of an emphasis. The average would fall into place. Of course, there are e...
by digger
Mon Sep 19, 2022 11:06 pm
Forum: Engine Tech
Topic: 128 my take, anybody see it like this ?
Replies: 158
Views: 4157

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

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. Is this in support of 128 or suspect of it's credibility? Curious o...
by digger
Mon Sep 19, 2022 8:48 pm
Forum: Engine Tech
Topic: 128 my take, anybody see it like this ?
Replies: 158
Views: 4157

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

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 n...
by digger
Fri Aug 05, 2022 12:33 am
Forum: Engine Tech
Topic: how much horsepower will a given size exhaust pipe support?
Replies: 10
Views: 626

Re: how much horsepower will a given size exhaust pipe support?

IMO this is probably the wrong question as it cant be definitively answered because it depends. The more correct question is what size(s) exhaust should i use for my application.
by digger
Thu Jul 28, 2022 5:20 pm
Forum: Engine Tech
Topic: Ever seen 8 rods disintegrate at once?
Replies: 24
Views: 2081

Re: Ever seen 8 rods disintegrate at once?

What gets me is the failure is almost identical cylinder to cylinder, separation just under the gudgeon pins, SM posted another video and he said this was not the case the failure was mostly midway through beam not close to the pin as people questioned the mods he did for clearance in the pin area ...
by digger
Sun Jul 10, 2022 5:39 pm
Forum: Engine Tech
Topic: Is Port Energy validation just around the corner?????
Replies: 79
Views: 10063

Re: Is Port Energy validation just around the corner?????

for variable port size i remember on these forums reading about a cone in a cone and moving them axially varied the area
by digger
Mon Jul 04, 2022 2:37 am
Forum: Engine Tech
Topic: Is Port Energy validation just around the corner?????
Replies: 79
Views: 10063

Re: Is Port Energy validation just around the corner?????

i agree that theoretically that two engines with same swept displacement and rod stroke ratio the theoretical "pull" on the intake is the same and this is verified if you do a 1D analysis. In the real world with 3D effects i don't think it is. If you think of a extremely big bore short stroke compar...
by digger
Tue Jun 07, 2022 4:55 pm
Forum: Engine Tech
Topic: Why all engine heads have relatively low exhaust port exit, compared to intake.
Replies: 35
Views: 1299

Re: Why all engine heads have relatively low exhaust port exit, compared to intake.

Exhaust runners are always longer than inlets so would be too hard to package with a very high port