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Custom head

Started by _Gunmetal LH_ , Feb 25 2010 07:17 PM

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49 replies to this topic

#1 _Gunmetal LH_

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Posted 25 February 2010 - 07:17 PM

For ages I've thought about the 202 head on my Kingswood and wondered about the intake and would a six-throttle manifold with fuel injection liven things up? Focusing more on the six-throttle aspect.

RB26 6 throttle.jpg 62.73K 77 downloads Maybe something like this- Skyline BR26 throttles and intake.

Then I figured once you modify/custom build the section to suit the Holden head, then the head will limit things anyway. So I thought about what makes the head so crap compared to others and realised (yeah I know- Derr!) the ports limit things, they just can't flow big numbers.

That's when I thought about the turbo lads using 'steam pipe' bends for various things. Me thinking more experimental than practical- I wondered about using something like the steam pipe to replace the intake and exhaust port-to-chamber sections?

My 'idea' is to remove the face of the head with the ports, and grind out the ports completely and weld in the steam pipe sections (90deg bend up from the valve seat and a straight piece to the manifold surface if needed) and re-weld on the valve guides etc. and weld a plate across the lot with the port holes, bolts/threads etc. to fill in the side again. This would give a true circle shape from the valve seat to the port which could be shaped accordingly to match the manifolds. The ports could be arranged intakes up high and exhaust low to give a bit more room for piping, and a straighter inlet path.

The other option may be to do both sides of the head and make it a cross-flow but I don't know how that would work with the pushrods?

DISREGARD COST & DIFFICULTY! I know it's not practical, I'm thinking about the THEORY of this working, NOT whether it should be done or another alternative.

What I'm wondering is- would a true circle shape and even bend in the port work performance-wise or would this actually cause problems re: airflow. IF done, would it be purely for crazy airflow only eg. turbo and stupidly high boost/revs or MIGHT this work for a street engine?

Could this (in theory only) be an improvement?

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#2 _Bomber Watson_

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Posted 25 February 2010 - 07:31 PM

Scrap the 90 degree bends and go 45 degree for the intake, 90 for the exhaust will be ok, run with the x flow idea, and im officially interested.

Make the pipe say 10-15% smaller than the valve....sounds very interesting.

Cheers.

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#3 _Bomber Watson_

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Posted 25 February 2010 - 07:38 PM

Even better, put the actual ports inside "outer" ports with an air gap in between, so that way the inlet isnt heated by the coolant and the exhaust isnt cooled by it (cooler intake is more power, and with a turbo hotter exhaust is power.)

Probably way out of line now....

Cheers.

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#4 _Gunmetal LH_

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Posted 26 February 2010 - 04:09 AM

Nope, not at all, it's theory at this point. I like your thinking. But I reckon it would still be affected by heat soak in no time. Or nitrous cool the intakes?
Save warming the bottle? <- I know, wrong concept for nitrous.

I'd match the port size to the inside diametre of the valve seats.

Along those lines- if it was for a turbo setup I would definately want the exhaust port cooled otherwise the exhaust valve + seat would overheat in no time and start to melt. <- educated guess.

Cooler intake, Hmmm, I'm thinking of a 'squiggly' coolant divider seperating the exhaust and intake ports to have engine coolant on the exhaust side, and a seperate system with coolant lines running to a small radiator for the intake side- something like an oil cooler setup with it's own fan?

With a crossflow head, I guess the intake could be on the drivers side and the ports made taller and thinner to fit between the pushrods. Exaggerated 'VN' style ports, a bit like gen3 heads? That would give it closer to a 45deg angle too?

The amount of work to do a crossflow I reckon make the whole thing from scratch with alloy plate and move the spark plug to the top/centre of the chamber. May aswell angle the valves too, could use offset rocker like the old hemi's. Could metal spray a stainless coating or go ceramic coating to protect against detonation. Maybe send the whole thing off to be heat, sonic and cryo treated.

Better heat dissipation with alloy from the chamber allowing for a higher compression ratio for N/A or more boost with turbo.

*off to the shed to look for some alloy* :bliss:

Edited by Gunmetal LH, 26 February 2010 - 04:13 AM.

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#5 _Bomber Watson_

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Posted 26 February 2010 - 07:47 PM

Mate i was thinking about this today at work and basically ended up exactly where you are now.

Start from scratch with a 30mm thick bit of plate lazer cut out, machine your combustion chambers into that (double quench type) canted valves to eliminate the shrouding problem, etc etc.

inside of the valve seat is probably about the right size for the ports i suppose, but not sure on that one.

Make one out of steel, put it on a flow bench, if it works make it out of alloy

I'll buy one off ya

Cheers.

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#6 wot179

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Posted 26 February 2010 - 07:50 PM

Even better, put the actual ports inside "outer" ports with an air gap in between, so that way the inlet isnt heated by the coolant and the exhaust isnt cooled by it (cooler intake is more power, and with a turbo hotter exhaust is power.)

Probably way out of line now....

Cheers.

Just tip it full of methanol and all of your problems will be solved.

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#7 _Gunmetal LH_

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Posted 27 February 2010 - 06:22 AM

Hmm, I like it! I'm thinking about N/A use aswell, but I still like it! *thinks sprint-car engines and smiles*

Here's another thing, I'd groove the head. (Just because I can) I actually read an in-depth explanation by an Indian scientist who actually worked out HOW the groove would direct gasses toward the spark plug. Something to do with the flow rates and different compressability of gasses. The way this groove in the quench area affected those gasses meant a better and more uniform flame front in the combustion chamber. No 'dead' area (the black ring) around the outside on top of the piston. He was applying for a patent on the idea but I think he didn't continue as people have been doing it for years anyway and it could be done with a dremel tool or even just a hacksaw.

groove2.jpg 51.04K 61 downloads

Edited by Gunmetal LH, 27 February 2010 - 06:25 AM.

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#8 wot179

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Posted 27 February 2010 - 06:30 AM

I reckon that will crack.

I wouldnt do it.

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#9 _Gunmetal LH_

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Posted 27 February 2010 - 09:46 AM

The article had a bit from an American team drag racing a 65 mustang. It showed the better looking burn patterns on the pistons. They dyno'd it and found no increase in total power but showed it was a bit stronger down low. The result (as they put it) was much smoother at low revs giving a much harder launch. Photo's showed a before and after of the pistons and chamber and they did look heaps better. The after shots were taken after another 30-odd runs and cracking didn't appear to be an issue?

IF I did the custom head I'd look at it, (making sure to finely radius everything) but I wouldn't be keen on doing it to a factory head. I'm pretty sure on MY old girl I'd end up with a 7 piece head...

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#10 _Viper_

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Posted 27 February 2010 - 10:04 AM

Ive thought about this too... how hard would it be to start from scratch? maybe even make a Twincam head with a belt drive running off the crank and disreguard the stock cam/pushrods... but then its like meh just go get a RB25/30

But still its interesting....

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#11 _Bomber Watson_

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Posted 27 February 2010 - 10:37 AM

Viper, how hard mate??? A frOcking lot harder than you think once you actually get into it.

Gunmetal LH, the notch is a stupid idea mate, only thing i can see it causing is detonation. That big "dead" area there is called your "quench", and when set up PROPERLY thats what directs the gasses to the spark plug, also causes nice turbulence.

Hence i said a double quench combustion chamger with canted valves, simmilar to a late model Harley head:

Posted Image

Thats something along the lines of what i would be looking at doing, actually quiet a nice design for a two valve setup.

That with a flat top piston at either 0 deck height or hanging a few thou out the block wolud be great, you could dome the piston in the middle where the combustion chamber is (keeping the outsides where the quench is) to lower comp or raise the same spot to increse comp....but probably best to do all your maths and work out how big to make the combustion chamber to start with :tease:

Cheers.

Edited by Bomber Watson, 27 February 2010 - 10:38 AM.

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#12 wot179

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Posted 27 February 2010 - 10:41 AM

mmmmmmmmmm...Hemi-headed red motor.

Now you're talkin!!

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#13 _Bomber Watson_

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Posted 27 February 2010 - 10:46 AM

Uhu.

See the drunken idiot has good ideas some times....

Funny thing is i have access to most the stuff i need to do this.....why arnt i doing it yet???

Other things to do.....

Pity VN 304 heads wont fit like the chebby ones do onto chebby sixes.

Yes i did measure a set i have laying around haha, no where near, i was bummed.

Cheers.

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#14 _Gunmetal LH_

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Posted 27 February 2010 - 11:47 AM

To Bomber: the groove/notch and detonation- aparently not? And yep, I understand the double quench. Would incorporate that anyway. And that underside pic is about what I was thinking with the spark plug near the top but not in-between the valves, allowing for bigger valves trying to get close to those valve angles too.

I was thinking of 4 valves and 2 rockers (SR20 style) but WAAY too complex welding in all those ports. I'd keep it 'red' and have 2 big valves.

I reckon I'd aim for 0 deck/piston height if making from scratch, then I could just grind away until I get the correct comp ratio.

To Viper: I'm thinking if I was to do cross-flow then definately from scratch. Would be cool to incorporate mods into a factory head though. I looked at a head from an RB25 and laid a 202 head gasket over it- no way. The RB25 head is too small, bugger. That would have REALLY s#!t some people off! There's always ford heads...

To wot179: Shhh! you'll give the game away...

Anyone got a gen3 head and a red block to compare???? Divide 5.7 into 8= 0.7125 Divide 3.3 into 6= 0.55 So although the bores on the gen3 block are closer, the bores on the 202 aren't as big so more between cylinders.

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#15 _Bomber Watson_

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Posted 27 February 2010 - 12:20 PM

Just measured between the plug holes on my 400 SB (same same).

Then measured same thing on Holden six head, to get a rough idea of cylinder spacing without really doing anything.

Within a couple of mill.....Why the hell didnt i think of that before....should i bother pulling a head off the SB??? Do have other things go do but god damb that could be cool....Motors only sitting together so not that much of a drama....

Cheers.

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#16 _Bomber Watson_

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Posted 27 February 2010 - 01:26 PM

Na no good, chev bore spacing is about 5mm more each cylinder, which is a big difference by the end of a 6 cyl haha.

Cheers.

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#17 _Gunmetal LH_

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Posted 02 March 2010 - 04:19 PM

Another question, is it possible (I don't THINK so) to weld aluminuim to cast iron?

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#18 _cruiza_

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Posted 02 March 2010 - 05:18 PM

if you are going to all this trouble why not 4 value it, find some jap crap motor with the righ spacing and make a twin head design welding two shortened heads togeitheir, Cams might be a bugger though?

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#19 _Bomber Watson_

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Posted 02 March 2010 - 05:37 PM

Because Michael if we wanted to do that we would do what oldjohnno is doing atm...

Plus i doubt it would make a huge difference, and yes i understand intimately why more valves are better.

Cheers.

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#20 _Gunmetal LH_

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Posted 02 March 2010 - 08:48 PM

cruiza- Too complex to section and join 2 heads. Holden or jap. 'jap crap' engine heads are usually too small (eg. RB25) or too complex to engage the overhead cam/s. The ford head is much easier to mod to work.

What I'd be aiming for is a stock 202 head modified to have 'true' circular inlet and exhaust ports that would be fed by a 6 throttle setup. (Overcoming the s#!t flow charachteristics of the factory head) That's the main theory/aim. The idea isn't for an OHC/DOHC (this time)

The reason why I wouldn't go a 4 valve head is simply too hard. It would be too hard to weld in double the amount of ports. I also like the idea of 'keeping it Red' and only have 2 valves.

As an alternative, I could make a whole new head in which case I'd use aluminium for the whole thing.

Had a good squiz at a spare head and I just don't think a crossflow is even possible using a factory head to start with. There is just not enough room to squeeze inbetween the pushrods, and that's disregarding the spark plugs.

Canted valves still look do-able though.

As a side-note the jap heads are excellent in my opinion. The funny thing is, overhead cams, 4 valve heads, fuel injection, superchargers/turbos and water injection, to have above 100% efficiency has been around for ages. Think WW2 aircraft engines. Makes it all 'old tech' really...

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#21 _mello92_

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Posted 02 March 2010 - 09:26 PM

May I please introduce the idea of Direct Injection?

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#22 _Bomber Watson_

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Posted 02 March 2010 - 09:49 PM

To expensive.

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#23 _mello92_

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Posted 02 March 2010 - 09:52 PM

Would you care to elaborate please?

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#24 _Bomber Watson_

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Posted 02 March 2010 - 10:09 PM

Have you ever seen the price of a new injector for a DI diesel truck??? Were talking 5k and up for an injector. Same as DI diesel utes/etc very very expensive.

The buyers of these new v6 commies are laughing untill it buggers up.

Ultra expensive uber high pressure fuel pumps, ultra expensive fitting/lines, etc etc etc.

And for what gain really??? .5 of a hp and 1ft/lb torque, and 5% better fuel economy over injecting the normal way just before the inlet port? $15000 i could think to spend better elsewhere.

Cheers.