NEVER MIND, I WENT A DIFFERENT DIRECTION AFTER POSTING AND FOUND SOME INFO FROM A B16

SUMMARY: need PRODUCTION STOCK specs for the J25A, or any 1.6L I4
Valve diameters 33mm/28mm
Lift heights around 3Krpm (valve lift, or cam lift with rocker ratio) 10.6mm/9.4mm lobe lift, rocker arms vary within the series from one engine to another.
Lift duration around 3Krpm, or event timing numbers I can use to determine duration. 230/227

BACKGROUND:
The most engine work I've ever done is stock rebuilds. To me, it's like putting together jigsaw puzzles as I mic/replace worn parts along the way. I understand the cause/effect of the moving/connected parts (e.g. rotational motion from crank reciprocates pistons by means of crank throws and conn rods), but when the conversation moves to tuning I'm a bit lost. I know that in other topics I understand things better when I find mathematical modeling, numbers I can punch into a spreadsheet and do my own engineering.

That said, I have this crazy notion to design and build from scratch a 2.4L flat-6 to go into an equally-original 1/2-ton 4x4. I have Engine Analyzer Pro from Performance Trends, but with so many variables and no ability to model an ECM, I'm having trouble modeling a respectable curve without also modeling rather poor mpg (35-40 lbs fuel/hour@2750rpm is GROSSLY unacceptable). I have a feeling my biggest problem is valve size/lift and cam duration... 2 intake valves per cyl., 1.25" valve diam, .515" lift, 223* dur.

So I'm looking for PRODUCTION STOCK specs from a similar engine, problem is I'm not finding anything other than valve count.

Can anyone help?

Thanks,
Homebrew

 

Early Porsche Boxsters had 2.5 liter flat 6 engines. You may be able to find the specs for that engine and use them possibly?
I might be able to give you some specs of that engine if you need them. Gotta dig through some service manuals when I get some time.

 

Thanks. I don't think engine config has as much influence on valve specs as do the displacement and application. The Boxster is designed to perform in the 5K-6Krpm range in a sports car on ideal roads where jack-rabbit sprints can be fun. I'm planning to operate in the 2K-3Krpm range in a truck towing a trailer and sometimes on bad roads where slow and steady gets you home.

My 1.8L 4-cyl Civic hangs out around 2500rpm on the highway, and while I've never seen a Saber I don't think they'd be terribly far off that mark. I rather imagine the valve diameter in the J25A is optimized for somewhere near the 2.5K-3Krpm range, with the VTEC mapping of lift, timing, and duration optimized for each RPM speed. I'll confess though, I don't know how VTEC works, just that it ain't spelt wif a H yo! (LoLz!) (sorry, I read the "read-before-posting" stickies and couldn't resist the humor)

I just happened to think, a 1.6L I4 would have the same displacement per cylinder as what I'm trying to make, so I might look that direction as well.

EDIT:
found some B16 valve specs, maybe VTEC isn't what I thought it was. Oh well. At least now I have some numbers.

 

Oh. I was thinking you were wanting valve sizes for a 2.5 flat 6 engine you were wanting to design. Guess I misunderstood.

Since your operating rpm range is so low, Is a diesel engine out of the question?

Maybe try and find some acura Vigor enthusiast site. Didn't that come with the j25 engine?

 

[QUOTE=PyroProblem;50445631]Oh. I was thinking you were wanting valve sizes for a 2.5 flat 6 engine you were wanting to design. Guess I misunderstood.

Yes I'm trying to design a 2.4L flat-6. I only wanted the valve size/lift/duration of an economy engine with similar displacement to put me on the right track in the sim. The B16, while a smaller TOTAL displacement, has the same CYLINDER displacement as my project, and is actually almost the same size as the Boxster you mentioned. The more I studied into it since my last post, it seems that valve size/lift doesn't do as much to shape performance curves as cam timing/duration and runner/port/header size.

Your suggestion to look at a Boxster was valid after all. My apologies for dismissing you so quickly. As I said earlier, I know how to assemble them, but I'm very ignorant about why things are the size they are.

 

There is a lot of information in this thread started by Tomcat39 that may be somewhat what your looking for.
https://honda-tech.com/engine-machin...tions-3246058/

no worries.