4G61 head info

jeffball610 · Post by **jeffball610** » Wed Mar 12, 2008 6:21 pm

There have been quite a few posts on here about the 4G61 head (1.6L DOHC) and how it can raise compression and has smaller ports. Yesterday, while at the junkyard, I came across a 4G61 in a 94 Hyundai Elantra. I wrestled the head off and took some pictures with my camera phone and took some notes. I happened to have my mircrometer with me and took measurements as well.

It seems there is no difference in the 1.6 and 2.0L heads. Valve size is the same as well as intake and exhaust port size. The only noticeable difference I saw was the pistons that had deep valve reliefs and a noticeable dome rather than the dish on the 4G63. I could not verify actual cylinder head combustion chamber size, but there seemed to be no difference between the 1.6 and 2.0 heads. The 1.6 did have a small marking on the back of the intake manifold reading "16" and another on the thermostat housing side of the head that had an oriental character and a 6.

This is by no means a definitive means to determine if the 4G61 head can be used to improve anything over the 4G63 head. It is instead a closer look at the 4G61 head found on the 94 Elantra and others may be similar. If anyone has more info on this and can verify or refute my findings, please post them for educational purposes.

Pics to follow.

jeffball610 · Post by **jeffball610** » Wed Mar 12, 2008 6:31 pm

First is the 4G63 head I had laying in my garage. Only 2 valves are in for comparison.

This is the 4G61 head I took off of a 94 Hyundai Elantra.

This is the domed piston of the 4G61 DOHC.

This is the marking I found on the thermo housing side of the 4G61 head.

This is the marking on the back of the 4G61 intake manifold. Very hard to make out the "16" above the "8".

I don't have a turbo 4G63 piston for comparison, but I do have a 4G63 non turbo piston in the garage for comparison. The non turbo pistons in the 4G63 give a static compression of 9:1.

89coltgt · Post by **89coltgt** » Wed Mar 12, 2008 8:50 pm

Some of the 4g61s had 1.8 heads iirc. The 1.8 heads have the same in/ex ports but the cr is the same as a 4g61 head.

marck_c · Post by **marck_c** » Wed Mar 12, 2008 9:40 pm

The 4G61T head is similar in many respect to the 4G63 Head but there are a few differences:

1. The combustion chamber volume is 43cc in the 61T, and 47cc in the 63T.
2. The 1.8 Liter version has the large intake ports similar to the 1st gen 4G63T. The 1.6 Liter version has the smaller intake ports, which are found in the 2nd Gen Version of the 4G63T.
3. The cylinder bore is 82.5mm in the 4G61 and 85mm in the 4G63T.
4. Valves, Springs, retainers are identical.
5. Cams vary obviously.
6. The stroke of the 4G61T is 77mm, the 4G63T is 88mm.

Hope this helps.

jeffball610 · Post by **jeffball610** » Thu Mar 13, 2008 1:58 pm

As I stated in my first post, the port sizes are identical to the 4G63 that I compared it with. If you have some measurements to verify that they are of a different size please post them. I measured the hight and width in the middle of the ports and got measurements of about 36mmX60mm on the intake and 31mmX50mm on the exhaust. Obviously the bore and stroke are different on each motor giving different displacements, but what caught my eye was the piston dome on the 4G61.

Perhaps the turbo 4G61 has a different port design than the 4G61 that I measured. Anyone have pics and measurements of any of the variations on these heads so that we can compare them?

richb · Post by **richb** » Thu Mar 13, 2008 7:43 pm

This has been talked about on the Mirage Turbo/Colt GT forum. It seems possible that the Mitsubishi 1.6 head might be diffrent from the Hyundai 1.6(L) head.

http://forum.4g61t.org/viewtopic.php?t=23264

Rich

jeffball610 · Post by **jeffball610** » Fri Mar 14, 2008 4:18 pm

I've read that post. There doesn't seem to be any pictures or measurements to verify the information. I don't doubt that my information is not all correct, but I took the time to measure and take pictures so that others don't just assume that posted information is correct. I'd really like to see some of these smaller port heads. They would make great heads for an all-motor 4G car.

I also took a quick picture of the 4G63 non turbo piston I had in the garage. As you can see, the valve reliefs are not nearly as pronounced as the 4G61 pistons I found.

emagdnim · Post by **emagdnim** » Sun Mar 16, 2008 12:18 am

From pulling a few heads off I've found that the hyundai heads usually have smaller intake ports then the mistu units usually.

Some of them are the same.

marck_c · Post by **marck_c** » Mon Mar 17, 2008 11:51 am

Some Hyundais came with the 1.8. This was a big intake port head, with the smaller 43cc combustion chamber of the 1.6 4g61. Otherwise identical to the 4g61. Some JDM 4g61's used this head as well. All the US 4g61's had the small intake port, 43cc combustion chamber head. The small intake ports on these heads are dimensionally identical to that of the second generation Eclipses (95-99).

gst95 · Post by **gst95** » Mon May 26, 2008 12:40 pm

More info found on the The Mirage Turbo/Colt GT forum. 43cc chambers will take the stock 1g 4g63 compression from 7.8:1 to 8.2:1. If you do a search for 4g67 over there it will bring up alot of threads. 4g67 is 1.8. Some 1.6 heads have big ports, but AFAIK all 1.8 heads are big ports.