A big valve 8valve is better than a 16valve head for 99% of tbricks
 

Change my mind.

No, you are correct. Especially if you port the crap out of it and gasket match.

Stainless steel exh valves are great!

My 531 is under construction. Only minor finishing on intake side and 38 exhaust valves. Good for 400 hp says the headmaster. Said also if using around 12 mm valve lift, 44 mm intake valves are fine.

Why would you ruin the flow by gasket matching?

You are correct. I see a lot of abandoned 16v swaps. Had they stuck with 8v that would more than meet the power goals there is a good chance the build could have been completed

Wrong. A cylinder head with better flow characteristics is ALWAYS better. If you had said "A big valve 8valve is better than a 16valve head for 99% of TbrickERS", then I'd be forced to agree.

It's like saying you didn't want to date the super-hot, super-nice chick because she was too high maintenance. Maybe it was just maintenance you couldn't do.

Hmmm isnt a bigger valve, ported 8v still cheaper than a 16v swap?
NA set up 16v all day, way more power under the curve.
Turbo Meh splitting hairs at that point. 16v make more but at what expense?

Now if the 8v was casted with a decent port shape, combustion shape, this would all change....

Lol

Yes but she is known to often be a tease where the fat bird is know to always put out :oogle::oogle:

I kinda wish I could make my valves smaller or add some sort of fins/grooves to them

So for me yeah I think 8V > big 8V > 16V

Does gasket matching mean making sure the intake and exhaust gaskets have the same internal diameter of the valves?

I think a well ported stock valve head would work for 95% of tbrickers.

spend the money on a real turbocharger instead

Certainly more than adequate for me, I also prefer the 8v sound. Call me a weirdo. IDK I'm not smart enough to argue the details. 16v does have its own inexplicable cool factor.

A 16v can use shorter duration cams so will have better mid range power and still match a 8v top end power, that’s the advantage I think of a 16v engine over a 8v.

No gasket matching is grinding the ports out so they are the same size as the gaskets. All it does is slow the gas speeds. The throat is not where there is any restriction in the head but around the valve stem is where the work is needed

Yes that is the advantage but you do loose torque and engine braking with a 16v. David Vizard has come up with the polyquad head that increases swirl and tumble to improve torque. Never see it done with a Volvo head and how much gain you get is a ?????

Well played, sir.

Right. You wine and dine her. Treat her nice. Then take her home to find out the tits are fake and that big bush isn’t the Brazilian that was advertised.

Damn! You guys gettin' nasty...

Actually turns out to has a huge big c*ck :roll::roll::roll:

Well, I've been running a flowed 405 with stock valves for a long time. It revs easily to 7k or more if you wanted to and runs better from off idle to redline than when I ran the engine with a stock head.

I think the 405 with flow work or any stock 8v head with work would easily satisfy most power goals for a fun street car while keeping it 8v simple.

Are we talking pure performance or driveability as well?

At the same power level, wouldn't a 16v have better street manners than an 8v?

yeah pretty much. the issue is not so much one of head choice but relative tuning ability. it is not limited to 16v cars either lol.

a better way might be to say "you'll have best results when you do not exceed your abilities as a mechanic", but then if you never try new things you'll never learn anything either.

It doesn't matter at all under boost, which is the only way I like my redblocks. But ya the worst part is directly under the valves.

Wrong. It matters boosted or not. Either way you are working toward optimizing gas flow.

Hi
well this is a easy argument to sort

in standard form
940 turbo 163 horse power

940 16 valve 153 horse power
so its a no brainier
if you use the penta head you get even more because of the comp ratio

so put the same amount of boost in to the 16 valve and you get 229 horse power
I run a 2.5 penta 16 valve on carbs and am very happy with it in my Amazon

Sure we know about the efficiency and total power possible. The op question is that the power you can make with a 8v would satisfy most people. At least that's what I thought he meant.

There is a level of mechanical complexity that you are adding and you can make fun power with a big valve 8v.

I like 16v too. Just happy with the power I've made with 8v for fun on the street. I have a 16v head stashed if I decide to make the leap. There was a really nice 245 with an n/a 16v at Carlisle last year that really caught my eye.

Wonder if that was the old Conner850 wagon..... he had a thread a few years back, but I believe he has vanished back into BMW land.....

Pictures are great, here's a relevant one: a cutaway of the 530 head's exhaust port.



https://i.imgur.com/cCcfFdEl.jpg

What are we looking at here?

.

My car was faster with a heavily ported head, as well as my brothers. I did them myself. I guess others results may differ.

You cut your LS in half and think it's better?

Ok & impressive feat, that...

Haha, I have more than 1 car, I would be more likely to attempt a W16 LS. And fail miserably

Yes. For 99% of tbers that want 300 horsepowers!!!1!0” an 8 valve head is plenty. Some bigger valves and an enem cam, which all bolts on using stock hardware, is more than enough.

whatchu need bigger valves for? 300 is easy on a stock head with an ipd cam. can't be a sissy with the mbc tho.

So on the average “tuned” set up someone can run lower boost to make their 300 safer.

I'm still working out the details for my feature on True Life: I spent $4,000 on an 8v head

what's considered lower boost? we're devolving into semantics, but I'd say 20-24psi isn't really "high" boost, but it's not necessarily "low" either.

Anything under a bar I’d consider “low”.

I think you'd struggle to hit that mark below a bar unless you had something special

There's no real use in gasket matching a 8v when you're using the stock intake manifold. If you do the math for port wall taper based on the valve size, the ~40mm intake port entrance is about right... the issue is the factory taper is very severe (over a short distance) and the rest of the intake port is undersized. Once you remove ~3-4mm from the middle of the intake port , you get into the correct approximate CSA and taper.

Enlarging the exhaust side too much will cause sever issues with reversion along the port floor as well. It is better to widen the exhaust port than to remove material from the roof and floor. This is what Erland suggests, and what I've seen from heads where I ported the exhaust too much. The port walls will be really clean, but have a pocket of carbon on the floor of the port.

Pocket porting and blending in the SSR is where these heads need the most amount of work.

It was a gray late model wagon. I think he said 91. M47 with a n/a 16v. Used a lot of Volvo plastic and made it look like a stock installation.

A stock b230 skinny rod NA aw70 is better than a 16valve head for 99% of tbricks.

Change my mind.

if it aint blown.... it sucks!

bigtime!

Gotta keep the kids safe somehow.

Back when we had gas that was all benzene based. The skinny rod B230 with M47 consistently delivered 30mpg or more on the highway. Then fuel changed and those numbers dropped a good bit.