Turbo head build

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Slant Six Bumblebee

Slant Six Bumblebee

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I have a stock slant six and am planing to turbo it and and going to do some minor head work when i pull the head. Arp studs and porting is a for sure. i do not want to spend the $700 to get bigger valses, should i get stock style replacement valves and backface them. Is it worth it to put in 340 valve springs with the stock cam. I live by organ cams and could get my cam regroud too for around $80 but do i have to get diffrent rockers, cam bearings, ect... (my core cam has some very minor rust on it). My budget is ~600 (not including porting which i will do myself)
 
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On a budget I would back face the stock valves, a lot of bowl work under the seats, gasket match, run the stock cam, at a minimum I would run some 318 or 340 springs. What kind of a turbo charger are you going to buy? I think that’s were most of the money if not all will be spent.
 
where do you get "$700 for oversize valves"? Is that JUST for the valves, or include machine work and valve job needed to put them in?
I have about $600 in the head for mine, including buying the valves (got mine from Oregon Cams, Hughes engines was a little more but not crazy so) and the machine work to put them in, plus (at my request) press in seats on the exhausts, a 70-thousandths shave, also had the tops of the guides shaved/ to make sure I do not get any interference, due to a higher than stock lift cam, they cleaned up/finished up my start to a home porting job, and they even magnafluxed it to be sure I didn't "oops" and grind into a water jacket, with my handiwork. I am contemplating a junkyard homebrew turbo setup for mine "down the road" but a turbo doesn't have to be "either/or". Everything taht will help airflow N/A will help with airflow when turbo'd, that much more. This is my 1st time on any engine doing oversized valves and/or porting a head.
If its bottlenecked when N/A it'll have the same breathing bottlenecks when turbo'd. I'd at least replace the valves (all of them) with new and clean up the nastiness and casting boogers even if staying with stock size valves. as well as back cutting them if the valves have the ridge like OEM ones did.
 
I have probably 1500 bucks in my factory closed chamber slant 6 head fully ported with 318 valves. It gets expensive. Plus, I've done some of the work myself.

I'm curious as to why you think you need different rockers?
 
volaredon said:
where do you get "$700 for oversize valves"? Is that JUST for the valves, or include machine work and valve job needed to put them in?
I have about $600 in the head for mine, including buying the valves (got mine from Oregon Cams, Hughes engines was a little more but not crazy so) and the machine work to put them in, plus (at my request) press in seats on the exhausts, a 70-thousandths shave, also had the tops of the guides shaved/ to make sure I do not get any interference, due to a higher than stock lift cam, they cleaned up/finished up my start to a home porting job, and they even magnafluxed it to be sure I didn't "oops" and grind into a water jacket, with my handiwork. I am contemplating a junkyard homebrew turbo setup for mine "down the road" but a turbo doesn't have to be "either/or". Everything taht will help airflow N/A will help with airflow when turbo'd, that much more. This is my 1st time on any engine doing oversized valves and/or porting a head.
If its bottlenecked when N/A it'll have the same breathing bottlenecks when turbo'd. I'd at least replace the valves (all of them) with new and clean up the nastiness and casting boogers even if staying with stock size valves. as well as back cutting them if the valves have the ridge like OEM ones did.
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That was just for the valve job. What a local shop said. How much did the magna flex run you and is that a good idea for a street engine
 
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RustyRatRod said:
I have probably 1500 bucks in my factory closed chamber slant 6 head fully ported with 318 valves. It gets expensive. Plus, I've done some of the work myself.

I'm curious as to why you think you need different rockers?
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The rockers were just for the cam regrind because it would be a smaller lobe.

I am aware that it can get very expensive very quickly I am just wondering what the best use of my money is.
 
Slant Six Bumblebee said:
That was just for the valve job. What a local shop said. How much did the magna flex run you and is that a good idea for a street engine
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so I assume that was with them getting you the valves, and them doing all the work? any porting included?

the magnaflux was included with mine. It was more of an "after check" to be sure the head didnt get ruined by the porting as there are some mighty thin spots in there to avoid, while porting. You grind too much, and the head is scrap metal. There are pictures of band sawed heads around to see where to avoid, as well as lots of threads right on here about the subject.
 
Slant Six Bumblebee said:
The rockers were just for the cam regrind because it would be a smaller lobe.
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Huh? Lots of us have put reground cams in our engines and never had to replace rockers because of it. With mechanical (solid) lifters just adjust for it when setting lash. with hydraulics if drastic difference you might need different pushrods but doubtful you'd need different rockers, because of "that".
 
volaredon said:
so I assume that was with them getting you the valves, and them doing all the work? any porting included?

the magnaflux was included with mine. It was more of an "after check" to be sure the head didnt get ruined by the porting as there are some mighty thin spots in there to avoid, while porting. You grind too much, and the head is scrap metal. There are pictures of band sawed heads around to see where to avoid, as well as lots of threads right on here about the subject.
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There was no porting included. How much should a shop charge for cutting bigger valves. My plan was no major porting and to just clean the casting and port the intake and exhaust manifolds. As for the machine shop the only work I would have done is the head resurfaced and maybe cut the valves. I would install the 340 springs and port myself
 
Slant Six Bumblebee said:
I am aware that it can get very expensive very quickly I am just wondering what the best use of my money is.
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search around here and ask a bunch of Q's if your search doesn't turn up anything. But with 160-some pages of content just in this section, someone here has "been there, done that". sounds like you have some "homework" to do, including maybe some basic engine fundamentals. not at all trying to scare you away/ We were all at that point at some time.
 
The head only flows around 140 cfm +/- 10.
I remember "porting" my slant head as teenager and later finding it flowed a whopping 175 cfm once I got a bench.
My point is.. the first 10 or 15 c f m is kind of easy, which one could say that about any head.. Maybe. There's a lot of precise work to get a slant 6 intake port over the 185-190-cfm hurdle...and there is water everywhere. So take it easy and just run it. It's just a stock cam and these don't RPM much without a lot of work... in comparison to a V8. PS I hope you're not spending 700 just for valves.
 
MOPAROFFICIAL said:
The head only flows around 140 cfm +/- 10.
I remember "porting" my slant head as teenager and later finding it flowed a whopping 175 cfm once I got a bench.
My point is.. the first 10 or 15 c f m is kind of easy, which one could say that about any head.. Maybe. There's a lot of precise work to get a slant 6 intake port over the 185-190-cfm hurdle...and there is water everywhere. So take it easy and just run it. It's just a stock cam and these don't RPM much without a lot of work... in comparison to a V8. PS I hope you're not spending 700 just for valves.
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Yeah I got a second opinion and found out on the valves. As for the porting I was not planning to go crazy as this is my first time doing any porting. I have a second rusty head I’m going to practice on
 
Slant Six Bumblebee said:
Yeah I got a second opinion and found out on the valves. As for the porting I was not planning to go crazy as this is my first time doing any porting. I have a second rusty head I’m going to practice on
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Search for ported slant 6 head or slant 6 porting on this site and you should find , eventually ,some pictures of ports that have been sectioned ...and in that post you'll find a post by me ...drawing over that picture and showing where to grind. Good luck
 
Yeah I had played with a scrap small block head once a couple of years before I dug into my /6 head. But it was still kinda scary, grinding on a head "for real" that I wasn't wanting to damage.
Which I did plenty of damage to the original seats as cut into the casting from the factory.
In my case the only way I could have run stock valves was to have had all the seats ground out for inserts. That grinder and carbide bits get away from you so easy.
 
Slant Six Bumblebee said:
Yeah I got a second opinion and found out on the valves. As for the porting I was not planning to go crazy as this is my first time doing any porting. I have a second rusty head I’m going to practice on
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Found out what, on the valves?
 
Slant Six Bumblebee said:
The rockers were just for the cam regrind because it would be a smaller lobe.

I am aware that it can get very expensive very quickly I am just wondering what the best use of my money is.
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No, it's not a "smaller" lobe. On a regrind, the lobe can have more lift than it did before, the lobe is simply "moved" on the core. You won't need new rockers, but you might need new longer pushrods.
 
You dont even need V8 springs as a turbo usually doesnt rev that high if you build it for full boost at midrange, ie a smaller turbo. Youll want a smallish turbo for a slant as the 225 wasn't really a revver with a 4.25 stroke. Turbos like to push on the rear gear so gear it low, like 2.93 or 3.23.
 
pishta said:
You dont even need V8 springs as a turbo usually doesnt rev that high if you build it for full boost at midrange, ie a smaller turbo. Youll want a smallish turbo for a slant as the 225 wasn't really a revver with a 4.25 stroke. Turbos like to push on the rear gear so gear it low, like 2.93 or 3.23.
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Chit. I wish you could come ride in Vixen. She'll get to 5500 fore you know what's goin on. lol
 
pishta said:
You dont even need V8 springs as a turbo usually doesnt rev that high if you build it for full boost at midrange, ie a smaller turbo. Youll want a smallish turbo for a slant as the 225 wasn't really a revver with a 4.25 stroke. Turbos like to push on the rear gear so gear it low, like 2.93 or 3.23.
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Concerning the valve springs, the pressure on the port side of the valve spring needs to be considered on turbo engines. Take your max boost times the square inches of the intake valve to calculate what the pressure is in the intake port that is working to open the valve. I would add that amount to the open-closed pressure recommended by the camshaft supplier to get to the recommended spring valve pressure.
This will not be a huge change, but I see it as the correct way to select valve springs on an engine with boost.
 
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