m20b32 11.0:1 CR cam selection

[doktor_b]

with oversized valves you need a new valvejob, cut throat size appropriately and massage the short side and bowl and blend it and streamline the guide a little better. probably some deshrouding to, most of the casting doesnt need to be touched

so i can have a decent local shop do this and not have to worry about them FUBARing the flow of the head. (*as long as the ports are all evenly massaged)

[digger]

so i can have a decent local shop do this and not have to worry about them FUBARing the flow of the head. (*as long as the ports are all evenly massaged)

key word is decent, ideally someone who is familiar with the m20 and what areas need work and what dont

[pantelones]

my research says that you dont want to spray too much onto the port walls as it forms rivers of fuel on the runners that doesnt burn well when it gets into the chamber and it is a safe bet the spary onto the valve.

You make a very good point. When I first started to look into building motors and head work I stumbled across a site that had the longer version of the link below. Have you (or anyone else...) seen this before or better yet, know someone that has played around with it?

http://www.allpar.com/fix/holler/head-porting.html

Also done on the valves...








He also puts a grove between the valves; this I have seen before and is an old flat-head trick the helps promote more even combustion in the chamber. I used to do this with the 5hp briggs & stratton minibike motors I played with while growing up, and it does indeed make for a more even combustion, and a bit more power. Was a 2MPH (25 to 27MPH) increase haha good old GPS tracking "Dyno". You can see a difference, but it's hard to tell due to the bad quality photos.















Also another interesting link that has head work done by the same guy...

http://www.sheenconsulting.com/car/main.html

And before you jump to the conclusion (first thing my dad stated, and he has been doing motor/head work for a long time...)

the grooves led to no cracks nor were they filled in by deposits, like some of the naysayers suggested would happen. The ST valves looked perfectly fine as well. Again none of the steps where filled in.

[digger]

the groove on the squish band is the somender singh groove or something. ive seen some people independantly test it and many people smarter than me have yet to adopt it

metric mechanic treat the valve like that to. the fact that many engine builders dont use it probably means it is more of a marketing thing. the sharp angles on the valve help to shear the fuel and break it up so im guessing a texture on the valve doesnt contribute much

certainly texture port walls and combustion work in alot of applications but some textures work better than others. the ones ive seen that have been tested to work are not like MM have at all though

http://hotrodenginetech.com/pipemax-creator-larry-meaux-on-race-engine-head-porting/

[pantelones]

http://hotrodenginetech.com/pipemax-...-head-porting/

Very good read, thanks for posting that digger!

The thing that really surprised me was that he was doing the texture everywhere. My dad has a lot of experience with the OHV V8's like the ones Larry was using as examples; the finish that he put on intake runners, and ports was identical to the finish that Larry uses, but he always "polished" the exhaust ports. Gains of 17WHP just due to the textured finish is pretty impressive. Also, the pipemax calculator was a really good thing to read about. I've seen you mention that a few times, but didn't know what you were talking about.

[ForcedFirebird]

Been meaning to try out pipemax. Bought Dynomation years ago, and to date, has been pretty accurate as long as data is entered properly. It was within 8hp on a 500+hp turbo v6 engine in which we designed the cam and ported heads/manifolds for. It has been pretty spot on for our N/A apps.

We also found that texture plays a big role in flow. Shiny ports flow slightly less than when roughed up a bit to a fish-scale finish.

[shadowracer]

any updates on the build??

[doktor_b]

any updates on the build??

i'm waiting on parts for the big engine and setting up my Megasquirt on my current engine.

[shadowracer]

I was going to do what you are doing build a 3.2, my thought was "go big or go home" the only difference being the bore (not by my choice), a few other things and boost.

I settled on an 85mm bore because of a mistake in the piston manufacturing (everything was to spec just not the bore). I figured ok I could add more boost with thicker cyl. walls and engine would have better longevity. So as it sits now its a 3.1L.

I have yet to boost the engine since I wanted to brake the engine in without the turbo first. Up to this point I can say so far without boost the car is a ton more fun to drive, I can't wait to feel the boost!

[doktor_b]

I was going to do what you are doing build a 3.2, my thought was "go big or go home" the only difference being the bore (not by my choice), a few other things and boost.

I settled on an 85mm bore because of a mistake in the piston manufacturing (everything was to spec just not the bore). I figured ok I could add more boost with thicker cyl. walls and engine would have better longevity. So as it sits now its a 3.1L.

I have yet to boost the engine since I wanted to brake the engine in without the turbo first. Up to this point I can say so far without boost the car is a ton more fun to drive, I can't wait to feel the boost!

that's awesome. what CR did you go with? i'm pretty sure i'll end up with ITBs and stay NA, so i went as big as possible and ran a bit more CR. if i were going to boost it, i probably would have gone with 10:1.

[shadowracer]

I went with a static 9.0:1. I almost went with a high comp. (12.0:1) NA build but then thought of the pain it might be to have to go and get race fuel all the time when I can boost and tune for pump gas.

I'm planning on going low boost around 5-8 psi for every day and track use. I'm also planning on getting an electronic boost controller so I can have my "woohoo" this is awesome setting:up:, or turn it up a bit to this is "crazy,":twisted: or really turn it up to have the "OH MY GOD SLOW DOWN I HAVE TO CHANGE MY SHORTS!" setting.

[doktor_b]

I went with a static 9.0:1. I almost went with a high comp. (12.0:1) NA build but then thought of the pain it might be to have to go and get race fuel all the time when I can boost and tune for pump gas.

I'm planning on going low boost around 5-8 psi for every day and track use. I'm also planning on getting an electronic boost controller so I can have my "woohoo" this is awesome setting:up:, or turn it up a bit to this is "crazy,":twisted: or really turn it up to have the "OH MY GOD SLOW DOWN I HAVE TO CHANGE MY SHORTS!" setting.

the last VW i built was a 3.2L 24v with 8.5:1 static CR. i put 15psi on it and it was a blast. (~3100 car, no driver, AWD) when i turned it up to 25psi, it was an absolute animal...but it was very hard on driveline components. (trans and clutch in particular) I'm sure yours will end up being a real blast, even on "low boost".

my wife and i agreed not to take the e30 too far because i have a goal to own a 911 by the time i hit 40 and it's closer than i care to mention. ;) So NA build and reasonable, budget mods for the e30 to hold me over.