head modifications...

[TDsamurai]

Hey guys i have an on going project and i work at a machine shop and i have a few ideas for a product i might start working on. First off if you havent heard of us check us out at northwestfab.com we have been specializing in offroad performance and fabrication for the last 8 years and we have been moving into diesel performance over the last year.

So lets get to the point.

After i get my samurai back together now that i am upgrading to a toyota transmission which should handle up to 300+hp i would like to get closer to that number down the road if possible.

As we all know the aluminum head is a weak link, from cracking between the valves, to it lifting off the block, or dropping precups from just too much heat.

Please if anyone has found a steel head available let me know as that would completely eliminate the headache i am about to get myself into.

So the idea up for discussion. I have been considering machining off the top and bottom 1/2 inch of the head to replace with steel plates to increase rigidity aswell as incorporating a better precup retension system. I would like to keep the machining as simple as possible so those capable or able to find a shop locally could do the work themselves, however down the road i would like to produce the kit aswell as offer the services to your head. I will be recieving my donor head for measurements hopefully in the next couple weeks. I would like to machine the valve seats into the steel to eliminate the aluminum web between valves that is prone to cracking. Obviously sealing between the plates and the head could pose a threat however with a smooth enough finish and some of the sealants available today i dont think it will be much issue.

This will be for when i get into doing a compound turbo setup as my single k24 wont be exceeding the limits of the factory head.

So what to you think? is it necessary? is it worth it? Only needs the upper plate or just the bottom plate? or both? I want to hear your thoughts and opinions as i think this could be the affordable answer to handling the pressures some of us horsepower junkies are looking for. We have both a 3 and 4 axis cnc mill in house as well as a cnc lathe with live tooling, so as far the machining other than some careful measurements and programming it should be rather simple. Let the discussion begin!

[MJF]

IMHO its not worth. Dropping prechambers is more like high mileage problem. Cup which is in one piece, will not drop. Cracking head is overheating, high power will not crack head. At this side of Atlantic, I havenīt heard that head lifting has been such a huge problem. One case that had 250whp @3700rpm, had problems when water/metanol injection was added.

[RabbitJockey]

Like a sandwich?  It does seem tho that alot of the people having head lifting issues were using stock intake manifold and turbos which can easily create flow biased to the center cylinders and the turbo used out of range can flow only hot air into the engine and then cause high back pressure which retains the heat in the cylinders and causes even high peak cylinder pressures.

[TDsamurai]

the reason i bring this up is i had an engine shop completely build my first engine, not that i am not capable but it was more of a time frame issue. nothing was spared and i ran the engine with mild tuning, 15-20psi turned up the fuel a bit. And i have all the gauges. I never went over 1200 degree egt for more than a second and i only got 15000km on it before the piston rings froze to the pistons and when the head was removed the precups fell out. The cracks between the valves were incredibly large aswell. I am confident my egt gauge is not the issue however i will ditch these cheap glowshift gauges i was running as i have had nothing but problems with the quality of them. The engine shop told me i ran it too hot and didnt cover a cent of the damage. Unfortunately it does seem like heat was the issue however my first engine was blowing about a cup of oil out the breather within 100km right after the initial start, when i informed the engine builder this they said it has to break in and that its normal until it is broken in and i need to drive it like i stole it to break in the piston rings... shortly after as i mentioned my engine was destroyed. I know the head is definately not the route cause of the issue however i know some of the cummins guys will run into the 1600 degrees for a suprising amount of time without issue. My engine pulls hard until 1200 degrees and has more to go however i do not want to get into those temps as the aluminum head i believe is a limiting factor.

Do you not think steel would allow us to run reliably into higher EGT's? or should i focus more on reducing my EGT's overall? I already have water meth, and a top mount intercooler with an electric fan. I plan on a cam regrind and possibly some ceramic coating as well as possibly porting the head and building a custom intake and exhaust manifold. Is anyone producing a performance intake or exhaust manifold that i do not know about? Would there be a good market for intake manifolds atleast? What would you guys be willing to pay for a good intake or exhaust? like i say sky is the limit and i am interested in selling some products for these engines if i could even get a few pre orders that could speed things up drastically. If i can get the volume i would hope to be able to make a nice intake plenum design for around $800-1000 or is that just too much? I think a stainless fabricated exhaust manifold could be done easier than the intake however the gain is probly minimal in comparison. Let me know what you guys think and what other components you would like to see. Is the plenum design the only route people would be interested in? or would something with just simply a bit longer runners work good enough for everyone?

[JamesT]

If you're replacing the bottom half inch of the head, that means you are going to need perfect machining to ensure the seal of 30 or so ports, including intakes, exhausts, precups, oil and coolant passages. That would be possible at a static temperature, but with a change in temperature it's a tall order. Throw two materials with different expansion coefficients into the mix, and you're asking for a miracle.
Another potential problem is the valves. They seat in the steel plate, but the guides are in the head, so as the aluminium expands, the seat and guide loose alignment and you loose compression. Or you could machine the thing to hot-dimensions, but then your engine is impossible to start from low compression.

In my opinion, it would be easier to just design and build a cast-iron head for it (which is a pretty tall order in itself). But then replacing one failure point with something stronger only points out where the next failure point is.

VW produces better flowing intake manifolds (PD130), but the runners are still really short.  Volvo diesels have a tube plenum and longer runners, and it fits if you cut the outer two runners off.

Stock exhaust manifold is pretty simple and flows well, but something that can scavenge may yield a bit more performance.

[TDsamurai]

That is the info i am looking for. i dont think the oil and coolant ports or even the precup chambers would be much issue with heat expansion obviously they would expand at different rates but the alignment of those i dont think would change enough to cause issue. I did consider the valve issue which was my main concern. I would love to get a cast iron head made but its just not affordable without the volume and not to mention who or where the casting is done could make or break the accuracy we need. I would like to see this volvo intake you are talking about if you had a picture that would be greatly appreciated. I wonder if even a 2 piece billet steel head or even billet aluminum would be possible obviously the cost would be excessive but it would be a fun experiment. I say two piece because to get the internal water jackets would be pretty well impossible to machine out of a single brick of material. Like i say the head is just an idea i have been thinking about. one of my problems is i like to get carried away with making things as strong as i can whether or not it is necessary is a different story. Thanks for the responses everyone.

[JamesT]

image stolen from TDIclub forums.

[TDsamurai]

Damn that almost makes it not work making anything haha, where can i get one and what engine model is it off of so i can attempt to track one down. Also will this clear the k24 in its factory position?

[JamesT]

You can get one off a diesel Volvo, engine model D24. It's the N/A manifold. The turbo one is quite a bit different. I'm about 99% sure it won't clear a K24 in stock orientation though.

[TDsamurai]

i did not say i want 300hp i said i want to get closer to it since my tranny can now take it. Ive already blown a trans and an engine that was completely rebuilt. I ran the diesel stock it weighed in under 3000lbs and i wanted more power i turned it up and i was somewhat pleased but i always want more. I would like to get close to 150hp reliably for now, and i would like to do compounds down the road. It would be plenty of power if i wasnt trying to jump it and drift it like a rally car as well as crawl through the rocks which hp doesnt matter since i have dual transfer cases. If i wanted an IDI with a turned up pump and governor mod i don't think i would be talking about steel head options lol. After the exo cage is finished and the toyota transmission with dana 300 transfer case i think i will be closer to 3400lbs. here is a few pics of what i have going on.





surprisingly i dont have any more up to date pics the intercooler was mostly for helping with crawling with the electric fan, there will be a scoop on it when i get it back together. and currently the exhaust stack is being redone in stainless and i added a small straight through muffler so i dont go deaf on the trail.

[745 turbogreasel]

Sounds to me like your shop may have been unfamiliar with VW diesel service, and blew it somewhere.
FWIW, my 250,000 mile motor hits 1400 on a long grade with stock fueling.

[TDsamurai]

I have been wanting to see what temps a factory vw hits, thanks for that info. Personally this is the first VW diesel i have worked on. I did not build the engine i took it to a local engine builder that i have used for other work in the past and i am under the impression they set the ring gaps incorrectly on the first motor. Im used to my cummins i can pull a steep grade at full throttle with 35psi and heavy fueling and not even break 1100 degrees.

[745 turbogreasel]

For that to be a fair comparison, you have to have ~10K on your trailer.

Lots of shops skim the head with the precups in, which removes the stickout that is supposed to keep them clamped in place...
and if it had previously overheated, they might have been loose in the bores to start with.
Last head I got done, I went to 3 local machine shops, asked what they wold do, and concluded it was a better deal to ship my parts halfway across the continent to have somebody who know his business do the work.  It actually cost the same, except with the local options, I might well have had to build the motor again.

[R.O.R-2.0]

Hey guys i have an on going project and i work at a machine shop and i have a few ideas for a product i might start working on. First off if you havent heard of us check us out at northwestfab.com we have been specializing in offroad performance and fabrication for the last 8 years and we have been moving into diesel performance over the last year.

So lets get to the point.

After i get my samurai back together now that i am upgrading to a toyota transmission which should handle up to 300+hp i would like to get closer to that number down the road if possible.

As we all know the aluminum head is a weak link, from cracking between the valves, to it lifting off the block, or dropping precups from just too much heat.

Please if anyone has found a steel head available let me know as that would completely eliminate the headache i am about to get myself into.

So the idea up for discussion. I have been considering machining off the top and bottom 1/2 inch of the head to replace with steel plates to increase rigidity aswell as incorporating a better precup retension system. I would like to keep the machining as simple as possible so those capable or able to find a shop locally could do the work themselves, however down the road i would like to produce the kit aswell as offer the services to your head. I will be recieving my donor head for measurements hopefully in the next couple weeks. I would like to machine the valve seats into the steel to eliminate the aluminum web between valves that is prone to cracking. Obviously sealing between the plates and the head could pose a threat however with a smooth enough finish and some of the sealants available today i dont think it will be much issue.

This will be for when i get into doing a compound turbo setup as my single k24 wont be exceeding the limits of the factory head.

So what to you think? is it necessary? is it worth it? Only needs the upper plate or just the bottom plate? or both? I want to hear your thoughts and opinions as i think this could be the affordable answer to handling the pressures some of us horsepower junkies are looking for. We have both a 3 and 4 axis cnc mill in house as well as a cnc lathe with live tooling, so as far the machining other than some careful measurements and programming it should be rather simple. Let the discussion begin!

those toyota/aisin-warner trannies wont hold 300hp for long.. not the 4 cylinder version anyways..

ive had a W56, a G52, and an R150 trannies all apart before..

do yourself a favor, and use a R150 trans... they are MUCH BIGGER inside.. the G52 and W56 trannies arent very big inside.. way thinner gears, lighter duty syncros, tiny input shaft as well..

[TDsamurai]

Yea the machine shop convinced me the stick out on the pre cups was unnecessary. My second rebuild i bought a brand new head assembled as my last on was unsalvageable. And the tranny I am using is and R151 from a 4cyl turbo model it is the big one and I've heard people running over 400hp in supras through them.