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Old 09-04-2020, 09:00 PM   #1
esmth
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Default K-jet head build for NA

Hello guys, I have a 1979 K-Jet 398 casting BCP head i've been thinking about getting work done on for a couple months now. The gist is that I want to modify this head to be more fun on the street than my bone stock B230F with B cam. After some reasearch here, I think some reasonable budget work for this head would be 46/38mm valves on cut stock seats, skimmed for more compression, along with a K cam and B21F intake I already have. I also want to stick with my current lh24/ez116k with a raised rev limit.

I have a couple of questions for those more experienced than I:

1.) Do the big coolant passages limit how much I can skim the head? What is a reasonable height to remove and static compression ratio to go for running premium gas?
2.) What is a reasonable valve spring setup for this cam (and an upgrade down the line) and an RPM my bottom end can handle? I currently have the "large" 32mm OD valve spring setup. I think I need new retainers for aftermarket springs?
3.) How practical are physically stock sized injectors in the K-jet head holes? I see its been done here before and I personally mocked up a fuel rail there with seemingly no problems. Though the ID of the injector holes at the bottom seems a bit too narrow.

I put together a cart on kl-racing with the above in mind, please critique it:
4x 46mm stainless intake valve
4x 38mm stainless exhause valve
4x valve stem seals
8x lower spring retainer
8x upper spring retainer
8x valve spring 39kg

I don't have much experience with asking a machine shop about engine work. If you have any tips or suggestions on what I should ask for (namely, the porting terms needed for bigger valve work) i'd appreciate it! Thanks for any input.
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Old 09-04-2020, 09:07 PM   #2
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I only know a little about question 3, why not use a B230 intake and these https://www.stsmachininginc.com/prod...n-turbo-models

A bit more info might be helpful, you talk about the lh24/ez116k you are using, and some may be able to determine what you have for fi now, but not everyone.
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Old 09-04-2020, 09:26 PM   #3
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Sorry, yes I should have added more info about my car in the post!

It’s a 1991 244 with a B230f and M46. I have LH2.4 with a 561 computer and 175 ezk. It has a B cam, adjustable gear (but set straight up) and a 421 tube header into a custom 2.5 exhaust. Otherwise the engine is factory.

I wanted to use the B21F manifold as the heresy is that it is better than the b230f intake manifold. And I already have it. Adapting LH injectors for Kjet holes doesn’t seem that hard, unless i’m overlooking something
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Old 09-04-2020, 09:39 PM   #4
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Ah, gotcha. Give the machine shop an injector (with new oring) with the head, tell them I want to fit this in there. I don't like giving a good machine shop numbers, they are better at measuring stuff than I will ever be.
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Old 09-04-2020, 09:57 PM   #5
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After thinking about this, that would be like direct injection, which may not be a real good idea. There must be a reason why direct injection is very high fuel pressures. And pretty sure the pintle caps will not stand up to the heat and pressure. Plus you lose the mixing effect with gas and air in the intake runner. How about having injector bungs welded to the B21 manifold, I forget who is doing that but it isn't hard to find. Pretty sure that is a better idea.

IDK, maybe someone else who knows more will comment.
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Old 09-05-2020, 02:42 AM   #6
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I don't know about that head, but I've used a 530 K-jet head & B21 manifold. I was using the Siemens Deka 630cc injectors & wanted to get their pintles as close to the runner as possible.
I used a couple of drill bits (16mm & 14mm) in a hand held drill to enlarge the existing holes so that the injectors fit. I don't think you could do this with the standard shaped injectors as they're fatter. I think there are later volvo injectors that you could do this with that are closer to the standard spray rates. This is not direct injection as you are still spraying into the intake runner/back of valve. Obviously you need to be very careful while drilling but it wasn't difficult.
The fuel rail fit without problem, just need to make up some brackets that use the K-jet injector hold down bolt holes. The Fuel pressure regulator was a problem- you would need to mount one remotely or as I did, adjust the mounting tabs on the rail & regulator to fit.
It's been done a few times on here - I was following a couple of threads. I was also worried about heat initially but had no problems for the 2years I used that head.
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Old 09-05-2020, 12:35 PM   #7
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Thank you two for your input.
The injectors will still be before the valve itself, only about 30mm closer. I grabbed some pictures this morning to better describe the situation with the fuel rail. I thought I had the later ev6-style injectors for a mockup, but I recently gave them to a friend so the photos are with the ev1-style, which turn out to fit better than expected.

Here is where the rail will sit


Injectors poking though, before the valve


Close up of injector tip near valve stem. The injector is about 2.5mm from the close side of the port wall, and 20mm from the far side.


ev1 injector is too fat, but the taper almost looks like it was meant for this, haha



tight fit, but it might work
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Old 09-06-2020, 12:15 PM   #8
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I drilled the plastic injector holders out when I did this. ^
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Old 09-06-2020, 08:14 PM   #9
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I hope it doesn't puddle when it sprays the back of the valve head.
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Old 09-06-2020, 11:05 PM   #10
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Quote:
Originally Posted by VB242 View Post
I drilled the plastic injector holders out when I did this. ^
Did that work well? Seems like a fellow could get some of those STS plugs linked above, and drill them. Or maybe STS would supply them with the proper I.D. shape.

Quote:
Originally Posted by 2turbotoys
I hope it doesn't puddle when it sprays the back of the valve head.
If that was a problem do you think they would have put the Kjet injectors in that location, spraying continuously?
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Old 09-06-2020, 11:13 PM   #11
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Quote:
Originally Posted by Harry Tuttle View Post
If that was a problem do you think they would have put the Kjet injectors in that location, spraying continuously?
Well K Jet is not a great example of fuel injection,. Maybe good for 40+ years ago, but the reason they moved them off the head is for better atomization. And pretty much every injection system since then has had them in the intake runner, it is just a better idea. But it will probably be fine, just not ideal.

The STS plugs would hold the injector pretty far away from the intake runner if drilled out.
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Old 09-07-2020, 06:38 AM   #12
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Quote:
Originally Posted by Harry Tuttle View Post
Did that work well? Seems like a fellow could get some of those STS plugs linked above, and drill them. Or maybe STS would supply them with the proper I.D. shape.



If that was a problem do you think they would have put the Kjet injectors in that location, spraying continuously?
It worked fine but I had to put the thicker k-jet injector O-rings on the electronic injectors. I'm now using a 530 head with regular intake manifold for the smaller cooling ports, I would like to convert a B21 intake though it did seem more torquey on the butt dyno.
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Old 09-07-2020, 12:37 PM   #13
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Big coolant ports are fine for NA. You can easily cut the head .100” or more and still be fine.
For springs, KL racing single springs will be fine.
For machine work, you’ll want to have the ID of the seats opened up to ~85% if valve diameter, and then have the bowl area blended into the port. Special attention should be paid to the short turn radius (sharp inside corner) on the exhaust and intake... but mostly the exhaust.
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Old 09-08-2020, 10:22 AM   #14
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I ordered the parts listed in the OP from KL last night!

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Originally Posted by culberro View Post
Big coolant ports are fine for NA. You can easily cut the head .100” or more and still be fine.
For springs, KL racing single springs will be fine.
For machine work, you’ll want to have the ID of the seats opened up to ~85% if valve diameter, and then have the bowl area blended into the port. Special attention should be paid to the short turn radius (sharp inside corner) on the exhaust and intake... but mostly the exhaust.
Thank you! I was most worried about how much I could cut the head. Good to know it can be a ton without issues atleast for NA.
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Old 09-23-2020, 10:04 AM   #15
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I got my order in and am almost ready to send it to the machine shop. Just need to remove two snapped studs.

I am trying to do research with how much I should take off the head and what static compression ratio to go for to run 91/93. This http://www.turbobricks.com/specs/sohc_heads.php says the it should be around 4.3cc of combustion chmaber volume per milimeter of head removed. If I remove 1mm/0.040in and run a 0.036in gasket, that should net me 10.65:1 theoretically. I'm not sure If i should attempt to run a thinner gasket and remove less material. Or if I should go for more compression, but it seems like more than that would be rough for lh24.

Theoretical SCR with 0.036in gasket on b230f bottom end and head shaved:
(assuming piston dish is 6 8 cc and head started at 51.7cc...)
0.020in: 10.32:1 10.03:1
0.040in: 10.65:1 10.34:1
0.060in: 11.00:1 10.67:1
0.080in: 11.38:1 11.03:1
0.100in: 11.80:1 11.42:1

Also I got some ev14 210cc cone-spray injectors from the boneyard and they fit much better than the ev1's. The pintle ends without the plastic retainer go in almost as deep as the original k-jet injectors. I think they will work nicely in the head.

Last edited by esmth; 09-23-2020 at 07:22 PM..
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Old 09-23-2020, 12:04 PM   #16
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0.040" and a thin gasket is a great setup for lh2.4 when running premium (91/93) with the B-cam.
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Old 09-23-2020, 03:25 PM   #17
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Dish on a B230F piston is 8cc. Our 530 head cut 0.103" measures 44.5cc.
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Old 09-24-2020, 09:32 AM   #18
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Quote:
Originally Posted by culberro View Post
0.040" and a thin gasket is a great setup for lh2.4 when running premium (91/93) with the B-cam.
Thanks! Though I'm planning on running the K cam I've held on to a bit. Could I go for more SCR with the K you think?

Quote:
Originally Posted by shoestring View Post
Dish on a B230F piston is 8cc. Our 530 head cut 0.103" measures 44.5cc.
Thanks! I had a hell of a time trying to find information about the -f piston dish. I ordered some plexiglass tiles to measure the volume of the head and pistons, but apparently that stuff is in high demand right now.
I adjusted the numbers in my previous post, do they look accurate to you? What about the volume of the 398? (I assume its the same as 530) I read somewhere that the head volumes could be as high as 54cc.
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Old 09-24-2020, 01:09 PM   #19
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Quote:
Originally Posted by esmth View Post
Thanks! Though I'm planning on running the K cam I've held on to a bit. Could I go for more SCR with the K you think?



Thanks! I had a hell of a time trying to find information about the -f piston dish. I ordered some plexiglass tiles to measure the volume of the head and pistons, but apparently that stuff is in high demand right now.
I adjusted the numbers in my previous post, do they look accurate to you? What about the volume of the 398? (I assume its the same as 530) I read somewhere that the head volumes could be as high as 54cc.
The K-cam should be fine as is. Both the B and K cam are pretty mild cams.

Chamber volume is all over the map, but somewhat consistent across a single head.

Dish volume is pretty consistent as well, but deck height is not. Which will have a decent impact on final SCR calculations.
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Old 09-25-2020, 11:45 AM   #20
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Quote:
Originally Posted by culberro View Post
The K-cam should be fine as is. Both the B and K cam are pretty mild cams.

Chamber volume is all over the map, but somewhat consistent across a single head.

Dish volume is pretty consistent as well, but deck height is not. Which will have a decent impact on final SCR calculations.
Oh OK, TY again for your input. i'll let y'all know what I get for volume when the plexi comes in
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Old 10-11-2020, 04:04 AM   #21
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Bump.

The B230 intake manifold is crap for flow out of the box and only slightly less crap when ported. The runners are just too small for great performance and will hold you back, so yes, the K-Jet manifold is better(straighter, larger diameter runners as well as a larger plenum). Some say that the throttle directly under the plenum is good, and others say it’s horrible(including Erland Cox). It is not ideal for air to have to make a 90 degree turn, but good power can be made even with the throttle underneath. We have a 90 degree elbow coming off of the stock TH opening and going to a 960TB with an 850 throttle plate at the moment in the General Leif and it would be over 165whp if we put it on the dyno in the current setup.

I like the idea of injectors in the head, but maybe there is a reason they don’t do it like that on modern cars anymore, aside from direct injection anyway.

Some of the Swedes(Erland) are going away from recommending larger valves for all but the most extreme engines. We’re still using stock valves but in a 405 head that mister Culberro here has played with for us.

For the K cam, you could maybe get away with more than .040” off the head and a .036” gasket, but realistically you will likely need to change your ignition timing. Factory ignition timing was more than needed by 4 degrees when we were around 11.3-11.6:1 with the Enem K13 camshaft at 155whp or so last year. We also blew up our 2.6L stroker a couple years ago and I’m not certain if it was because of an oiling problem, a ground crank problem, or running close to stock levels of ignition timing problem. Maybe so the above! That was a total bummer to have it blow up only 30 minutes into a race weekend.

10.5:1 SCR is probably all I would try to go for if you don’t have the ability to tune the ignition timing(I could maybe burn you some basic chips if wanted at some point). That would be around a 48cc chamber. If you’ll go with a more aggressive cam at some point, you would want to go higher. The common ticket is shave 2mm from the head(with a stock head gasket) in Europe when putting a real, although still smaller, cam in these cars. Larger than the K but still far from wild. They have better gas available to them, but even still it should be ok on our pump gas as long as you keep the timing in check. Do you have an Ostrich and can you go to a dyno? Lol.

Here’s the SCR calculator I’ve been using mostly, and some different SCR calculations with varying cylinder head combustion chamber volumes assuming your pistons are approx. .010” above deck like seems common foe B230s in my experience.

http://www.csgnetwork.com/compcalc.html
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Old 10-11-2020, 04:07 AM   #22
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Quote:
Originally Posted by shoestring View Post
Dish on a B230F piston is 8cc. Our 530 head cut 0.103" measures 44.5cc.
What headgasket are you guys running and what is your SCR you’ve calculated? Piston deck height? I can’t remember if you guys are running less timing than stock, as you’re still on the K cam, but that 2.5km off the head seems like a lot assuming you are running thinner than a stock HG and just the K cam. I know it’s working well for you, though!
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Old 10-12-2020, 10:35 AM   #23
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Thanks for your input! The plans may have changed a small bit, 2 weeks ago I found a 1995 L block in a junkyard so I spent the entire weekend pulling and scooping that up. So now I have a fresh SCP 530 head and L squirter block that I may have the work done to instead of the 398. I do still want the injectors in the head w/ b21f manifold though.

I did a fuel system refresh this past weekend to get it ready for an aftermarket fuel rail with brand new injectors. I found the top of my tank to be covered in rust holes, so I need a new one first.

About the valves, I already bought them so they're going in

About the ignition timing changes, I do have an ostrich and have been messing around with it, but I am still new to the ignition tuning thing. I get the concepts like why the ignition would need to be retarded in this case, but have very little hands on experience. Would a way to listen for knock help me out here?

About the cam, I already have the K so that is what i'm going to use for now. A more modern/fun one is definately on the radar though
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Old 10-12-2020, 04:11 PM   #24
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That all sounds fine!

Just a warning
, the compression ratio calculator I have been using(as shown in the above pictures), may actually be "low" in its calculations I am finding out today... So, the compression numbers above are maybe only good for comparing between each other, but getting an actual static compression ratio number might be different than what you're seeing here.

The 530 head is not set up for injectors in it, so you will have to get it machined, or use the 398 head. I don't think there's any major reason NOT to use the 398 head in a non-turbo, it should be just fine, even with the BCP. We are running a 405 BCP with supposedly over 3mm/.120" off and have no related problems in an endurance racing situation where we drive the piss out of it, literally all day long or longer.

The K cam will be fine and fun for now!

I can email you some EZK bins and an XDF for you to tinker with(if it's not already in my sticky'd thread). Basically though, the stock ignition timing maxes out around 34° advanced and we didn't lose any power/torque on the General Leif going from 31° down to 29° or so at peak torque. We didn't spend any time dialing it in further as we had already been on the dyno for a while trying to dial in the fuel side of things. So, you could take the stock ignition timing and reduce it a couple degrees and see how it works for you. On my street car(stock b230F, .036" gasket, somewhere around that taken off the head, around .010" piston poke and a Singh groove with H cam), I was having some mild detonation issues with any real load around 2000rpm or so and had to reduce timing there if not using premium fuel or on hot days. That hasn't been on the dyno so I haven't dialed it in aside from lowering the maximum timing at WOT to 32° based on our history with the General Leif.

Last edited by klr142; 10-12-2020 at 04:18 PM..
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Old Yesterday, 07:17 PM   #25
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Is this bad?

This is cylinder #3. The crack doesn’t progress in the ports at the bottom of the seats. Cylinder #1 is also starting to crack but it’s not nearly as bad. the other cylinders are fine.
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