10.5:1 CR Goal with Hyundai Head

[turtlebain]

Because of a lot of people's success in generating HP & TQ numbers with E85 and higher compression, I want to aim for 10.5:1 in my build. It will be tuned using ECMLink V3 Full & Speed Density.

I have the Hyundai cylinder head which is said to have a 43 cc combustion chamber on a virgin head. I was told the smaller combustion chamber would raise the compression slightly, and what do you know, it has raised by 0.55:1. However, there are 3 assumptions built into that calculation

Calculated CR 9.55:1 *based on assumptions & Calculator on Engine Compression Ratio (CR) Calculator
=========================================================================
Enter Cylinder Bore Size----------------------------86.524 mm
Enter Piston Stroke Length--------------------------88 mm
Enter Head Gasket Bore Diameter-----------------87 mm
Enter Compressed Head Gasket Thickness-------1.27 mm (*Assumed same as stock -> .05 in)
Enter Combustion Chamber Volume In CCs------43 (*Assumed no previous milling)
Enter Piston Dome Volume In CCs-----------------10 Dish
Enter Piston Deck Clearance------------------------0 (*Assumed)​

Things I need to figure out:
* What is exact compressed HG thickness? How to find out exactly which head gasket I have? It came with the built short block.
* Goal 10.5 CR - what are my choices? machine head for smaller combustion chamber, different HG or other?
* I also performed a Hydro test on the head to see how well the valves held.. Water dropped about 1 cm overnight. Should this be ok?

 

[My1GLaser]

Is it an MLS HG? The OEM and Felpro MLS are both in the neighborhood of .050-.054" compressed. I've had both, but don't remember off the top of my head. Run a Felpro composite which is .039" compressed. That alone will bump you to 9.78CR

You can machine the head a little so it has a nice mating surface, but they probably won't take off more than .005" If my calculation is correct then you will lose .75cc on each Combustion chamber. That bumps it to 9.9CR

Not sure if your pistons will be flush with the deck or not. From my understanding, stock ones are down in the bore around .010". In my built motor they are about .007" above the deck surface. That brings it up to 10:1 CR

If you change the deck surfaces too much then you will want adjustable timing gears to get the timing geometry back in line.

Those are just ideas, but why not just get 10:1 pistons and be done with it?

 

[turtlebain]

Is it an MLS HG? The OEM and Felpro MLS are both in the neighborhood of .050-.054" compressed. I've had both, but don't remember off the top of my head. Run a Felpro composite which is .039" compressed. That alone will bump you to 9.78CR You can machine the head a little so it has a nice mating surface, but they probably won't take off more than .005" If my calculation is correct then you will lose .75cc on each Combustion chamber. That bumps it to 9.9CR Not sure if your pistons will be flush with the deck or not. From my understanding, stock ones are down in the bore around .010". In my built motor they are about .007" above the deck surface. That brings it up to 10:1 CR If you change the deck surfaces too much then you will want adjustable timing gears to get the timing geometry back in line. Those are just ideas, but why not just get 10:1 pistons and be done with it?

Yes, it's a cosmetic MLS head gasket, not sure of the thickness.. I could always measure it with my caliper. But it's sealed from dust and debris at the moment and I would have to re-seal it.

As for why I didn't go with 10.5 pistons? Because I didn't choose the pistons. I bought the short block completely assembled. Can I mill even more off the head until I get combustion chamber small enough? Or should I call it quits at 10.1? The goal is 10.5:1, but if it's too risky, why chance it? Why would I need adjustable timing gears?

 

[My1GLaser]

I really wouldn't go machining the head until the combustion chambers were small enough to reach your 10.5:1 goal. http://www.dsmtuners.com/forums/cyl...how-measure-4g63-cylinder-head-thickness.html

My head is about 5.175 right now. I have had it machined twice and it was machined before I got it many years ago. I clayed my pistons and have tons of clearance with my HKS 272s.

To get the highest CR on your set up without changing pistons or machining the hell out of your head you are going to have to run a composite HG and not the Cometic MLS.

Using adj cam gears get your cam to crank timing back into proper relation to each other from repeated head/block resurfacing. You would have to degree your cams to do that though. It is also a good idea to clay your pistons to make sure you have enough valve to piston clearance. It becomes more important with high lift cams and close piston to head clearance.

 

[turtlebain]

I didn't exactly want to spend on some adjustable cam gears but if I have to I will.

I don't think the head measurement thread applies to a Hyundai head. Maybe it does, I'm unsure of what exactly the differences are between the heads. From my understanding they're mainly the same as a 1G head besides the smaller 43 cc combustion chamber. I don't know of any other differences. Claying the piston-valve clearance seems like a smart thing to do. Has anyone else milled to the extent that would get me up to the 10.5:1 mark?

 

[GSXeclipsePSI]

Hey bro. I wanted to chime in. The head has been resurfaced by me when I built the motor 1st time. Was not sure how much they took off. Also you have to factor in how much was taken off the engine block also if it's not a fresh block. I'd do all the measurements to make sure. The head didn't have any damage I just had it resurfaced so not much would have been taken off. Just double check. You might have to go adjustable and learn how to use that special timing circle thingy. Forget the name but it's not too hard to figure out. If I wasn't 1200 miles away I'd help ya out. Just text me if you got any other questions about the head.

 

[turtlebain]

I'll have to get back to you guys when I get exact measurements of the head and block. Still need to measure block to piston clearance anyway to get a true CR calculation. Thanks for all the input so far.

 

[Gerg]

This is a 1.6L head correct? I currently have one of these heads laying around and I've always been interested in what car it originated from.

I have noticed the combustion chamber is slightly different shaped, the combustion chambers aren't exactly round like a 2.0 head is. The exhaust ports are also slightly smaller in size, however the intake ports look basically the same.

The head has a pretty rough casting, the oil drain was almost completely obstructed on my head.

 

[Archer Fabrications]

If your going straight e85 why not 12.5:1? I have a buddy local doing this and it's gonna be a monster. Hes injecting alot of methaol with pump gas too.

 

[turtlebain]

Hey Greg, the one I have in particular has been ported also. I know they come in 1.6 and 1.8L versions, but I don't know which cars they correspond to. I don't know which one I have either, but they should both share the 43 cc combustion chamber, raising the CR around 0.5:1 by calculation

Urban - because I would need to swap pistons and don't want to over-complicate tuning.

 

[Gerg]

Hey Greg, the one I have in particular has been ported also. I know they come in 1.6 and 1.8L versions, but I don't know which cars they correspond to. I don't know which one I have either, but they should both share the 43 cc combustion chamber, raising the CR around 0.5:1 by calculation

Urban - because I would need to swap pistons and don't want to over-complicate tuning.

They usually have a number cast in one of the sides, I believe it would be on the thermostat side. Just curious as these heads are kinda rare!

Here's a picture of the 1.6 that is stamped near the top of my head.

You must be logged in to view this image or video.

 

[My1GLaser]

Has anyone with the 1.6 head or 2.0 Hyundai head had any issues with a 4g63 cam being too tight in the cam journal? I bumped into a thread where someone said they had an issue. I only have a 0-1" Micrometer or I would just measure it myself. (The cam journal is a tad over 1") I tried using my digital dial caliper, but I wasn't getting consistent results.

I am going to be running a 2.0 43cc Hyundai head with small intake runners so I am curious of the answer.

 

[lasthope05]

No problems here. Using a G4CN 1.8l head. The 1.8 heads have 1g sizes ported and the 1.6 as 2g style but more oval. Both are 42-43cc. I have the stock Hyundai cams if you want me to measure them.


If I were you I would do a piston change. There is no way in hell you are going to be able to safely mill the head and block enough to drop a full compressing point without kissing valves or offsetting timimg w/o timing gears You can weld the combustion chambers up and raise compression that way but at that point it's cheaper to just new slugs.

 

[GSXeclipsePSI]

He is using the old hyundai cams I forget the letters stamped on them but when I owned the car I had the cams sent to DeltaCams and had them re ground to Hks 272's. Now I don't remember if they use urs or cores he would have to check letter stamp on the camshafts. Also delta said to use spacers under lifters to make up for lost material. But at the same time I didn't install the washers cause they fell out of the box. Found them later and now he has them to iinstall. But I wondered did they need spacers still since I put the 3g lifters in and they are a few mm taller. So I would imagine they would make up the gap automatically. The intake ports were ported but not gasket matched to try and keep the entry angle correct since that was the benefits to the 2g intake ports. The exhaust ports I ported also but to match a 2g manny at the time and a close to mirror finish. I later added FP manifold which would benefit the head to be ported/gasket matched. He is also using a 1g intake manifold with 2g TB. I can post pics of head when I got it I know I have pic of part number on side of head cause back in 2008/09 info was limited. And for everyone to know the hyundai head had 1g thermostat housing and the larger head studs holes making it perfect for a 6 bolt block in a 2g. It was by mistake I got this head. As I brought the 1g head to be looked at. Shop went ahead and fixed her up all stock and said ok $350 please. I said wait I wanted you to look at it. I had bigger plans for this head 1mm over and maybe some other things. So guy goes in back comes out with the head in question and says well heres a head in the condition urs was in. Have a good day and get out. So it looked ok at 1st til I got home and noticed 2g ports and the strange stamps. But they wouldn't return my calls after that so that was that. I'll post pic of head stamp.

Update:
Sorry my computer crashed a year ago. Any more pics I had other then ones in this Dropbox link are lost or I already sent to turtleBain back when I sent him every pic since 2003 of the cars progress. He can provide the stamped code on side of head. I did all the porting. Valve job and decking were done at a more local shop who was half the price and did more work then the $350 price/job on 1g head.

https://www.dropbox.com/sh/vjpoy6qzsre703c/ELBin7Ue4E

 

[turtlebain]

Guys, I've been really busy the last couple days, so I haven't been able to post any details. I should be able to tonight.

A few more questions..

Is it really unsafe to mill the head down further for higher compression? By calculation , the combustion chamber would need to get down to 37 cc for 10.5:1 CR. How do you calculate how much to take off? Would the machine shop know how to get it to this spec? I would be checking valve clearance using the clay method if I were to go this route.

If I were to go the piston swap route, what else would I need? The only thing that comes to mind is a ring compressor. Already have massive amounts of assembly lube.

 

[BogusSVO]

It is about .007-.008 to close a combustion chamber up 1cc.

Since the head was milled once, lets just say .007, and that would make you 42cc.

so to get to 37cc, you need to close the combustion chamber by 5cc more.

so .007 x 5 = .035 appox needs to be milled.


Now if the head has the common 4g head thickness of 5.200

less .007 for the first surface makes it 5.193

Now 5.193 - .035 = 5.158

That to me is too thin.

Also if you go to any cams that have much lift to them, that will compound the valve to piston issue.

 

[GSXeclipsePSI]

He has DeltaCams Hks 272's installed

 

[turtlebain]

Also if you go to any cams that have much lift to them, that will compound the valve to piston issue.

Hyundai Stock HKS 272 Delta regrinds. Should not have more lift. So you're thinking this will be too tight.

Kendel beat me.. damn

 

[BogusSVO]

The HKS cam have a .396/.372 lift, most of the "alphabet" cams are in the .330 range

http://www.dsmtuners.com/forums/cyl...5135-camshaft-identification-information.html

so that is appox .066/.042 lift from a stock cam

Now most aftermarket forged pistons will have deeper valve pockets, so this will off set it some.

Also keep in mind when you mill a 4g head below 5.170ish, you get into the valve seat insert.

So now you have to sink the valve some, and that will lower the compression some.

Now I almost forgot about this thread,

http://www.dsmtuners.com/forums/cylinder-head-short-block/464400-delta-hks272-regrind-info.html

 

[lasthope05]

Just get new pistons or stick to what you have and don't waste your time. You're going to trash the head milling it that much. Its a simple solution, don't over complicate things.

Besided, if you cant replace pistons and size them, I don't think you have the experience nor tools to properly measure and clay reliefs.

 

[1qkfwd]

Not sure if you guys are aware, but the casting on a 1.6L big port head is thinner than a 1G head. You will get a bit more flex and have more head gasket issues than with a 1G head. Then the 2G head is a bit thicker than a 1G.

Bumping up the compression that much your going to run into head gasket issues.

 

[My1GLaser]

Have you cc'd the head you have? I have a 2.0 DOHC head from a 97 Sonata with the smaller intake ports and I thought it was supposed to have the 43cc combustion chamber.

I filled one of the CC with water and used a turkey baster to transfer it to the CC of a spare 1g head that I have in my shed. They are the same size. So I don't think this is the 43cc head, unless by Dale's calculation the 1g head I have has been milled by around .030". I'll have to measure tomorrow, since we are in the middle of an ice storm right now and my yard looks like a war zone from all the fallen branches.

 

[turtlebain]

Not sure if you guys are aware, but the casting on a 1.6L big port head is thinner than a 1G head. You will get a bit more flex and have more head gasket issues than with a 1G head. Then the 2G head is a bit thicker than a 1G.

Bumping up the compression that much your going to run into head gasket issues.

Your recommendation is to go with a 1g or 2g head then with a 10.5 CR Piston?

Have you cc'd the head you have? I have a 2.0 DOHC head from a 97 Sonata with the smaller intake ports and I thought it was supposed to have the 43cc combustion chamber.

I filled one of the CC with water and used a turkey baster to transfer it to the CC of a spare 1g head that I have in my shed. They are the same size. So I don't think this is the 43cc head, unless by Dale's calculation the 1g head I have has been milled by around .030". I'll have to measure tomorrow, since we are in the middle of an ice storm right now and my yard looks like a war zone from all the fallen branches.

I have not - anyone else have similar / counter evidence? It seems there are 2 different sized combustion chambers with Hyundai then. Any gurus want to chime in and settle this?

Also - I'll try to measure mine when I get home.

 

[My1GLaser]

I just measured and both heads are virgin and measured at 5.2". I realize I didn't actually cc the heads using a pipet and piece of plexiglass, but I feel that I compared the sizes pretty well. I would have had to been really inaccurate to miss it by 4cc, but I guess anything is possible.

 

[1qkfwd]

Have you cc'd the head you have? I have a 2.0 DOHC head from a 97 Sonata with the smaller intake ports and I thought it was supposed to have the 43cc combustion chamber.

These Sonata heads are based off a 2G design, but have smaller ports than even the 2G.

Your recommendation is to go with a 1g or 2g head then with a 10.5 CR Piston?

I would suggest one or the other yes. Dave W. was using a 1.6 small combustion chamber head at one point discovered that the head was a thinner casting. He was having gasket issues a lot.

The 2G head is going to be by far the superior head all the way around. I wouldn't get to hung up on the combustion size for our engines and trying to get at that 10.5:1. Get a thinner gasket and some high comp pistons and you should be close.