Additional 4G64 w/ DOHC head questions

Jed118 · Post by **Jed118** » Mon Oct 27, 2008 4:53 pm

I have aquiered the following:

-1989 Hyundai Sonata block (4G64 SOHC) 6 Bolt
-1992 Hyundai Elantra Head (4G67* DOHC) 6 Bolt

* their combustion chambers are 43cc vs. 47cc of a 4G63

I've almost sold enough old 486's on eBay to have $$$ to buy these pistons!

The highest compression pistons I could find were 9.0:1 however I am under the impression that using those pistons (9.0:1 Wiseco) and the smaller chambers I will get apporx 0.3 - 0.4 upscaled compression.

If this is infact not correct, where could I get higher compression pistons? I don't think im ever going to turbo it (albeit I will have a turbo manifold, as none exist for N/A RWD application), although if I do it will be very conservative boost (no more than 5psi)

Now then, mating these together, I read that the chaincase cover is different (where the oil pump and those stupid counterbalancers go)

Do I need a DOHC case, or a SOHC case?

Also, are there any good N/A cams for these cars, or will I have to custom grind them?

In case you're wondering, I'm going to be using two Weber DOCE 45's to fuel this beast, with as long a runner as I can fit into the motor.

89coltgt · Post by **89coltgt** » Mon Oct 27, 2008 6:08 pm

You need a hohc 6 bolt front case. Afaik, nobody makes and off the shelf set of na cams. Some of the piston manufacturers make custom pistons and they are not priced too bad, you may want to contact them with your needs.

jeffball610 · Post by **jeffball610** » Tue Oct 28, 2008 12:21 am

The project sounds interesting and different that what anyone else here is doing. 89coltgt is right with his info. You should be able to order even higher compression pistons if you want. I know Magnus and others can get custom domed pistons made. There is definitely a 10:1 piston out there.

However, with the 2.4L and the DOHC head, you can get a nice compression boost without using aftermarket pieces. The 6-bolt rods should be good for 400hp and since you're staying NA, the stock pistons should be just fine as well. I would concentrate my efforts on a good cam to match those Webers and some spark control. You might look at something like Megasquirt since you're just going to need spark control.

Also, since you're staying NA, you might look into using a 1.6L head since it has smaller runners. The 1.8 and 2.0L heads have very large ports. And you might be able to steal a tubular header off of a 2.4L SOHC Galant (same bolt pattern as DOHC). I believe they end before the bottom of the block and can have a custom exhaust bolted up from there. (you'll need one anyway)

Hope some of that helps. Let us know if you're unclear on anything else.

Jed118 · Post by **Jed118** » Tue Oct 28, 2008 9:44 am

so, use a 4G61 head then? I could scour the yards for one, but if I know myself, I probably WILL end up turboing it... just like my current 4G32 (which I said I would be happy w/ NA) Here's an early vid of it (exhaust exit has since been angled properly)

http://www.youtube.com/watch?v=Q3FodDCJXsM

I'm more than likely going to use a Millenia S (Miller cycle worm gear SC) or a Toyota Previa SC (from a 2.4 - roots) - something small that can adapt to the A/C bracket and feed that Rochester 2G (from a 305) with a little bit of force

Anyways, I know I won't go over 400 HP with the 4G64. I read about oil squirters and that a good set of pistons should negate the need for them. Im certain I want to use aluminum pistons, but I'm not sure about the rods: Do they withstand a good deal of pressure?

I guess I'm going to start dismantling the motor after this week (Hallowe'en parties, essays to write, winter cars to make ready for myself and wife) and go from there...

How much approx power would a stock 4G64 DOHC make, just for comparative purposes?

jeffball610 · Post by **jeffball610** » Tue Oct 28, 2008 2:19 pm

Well, before you tear anything up or build and buy parts, you need to decide what you're doing. If you're going N/A, then your parts and goals will be completely different than a turbo motor.

If you stay N/A, then the stock internals will work fine. I suggested the smaller ports on the 4G61 head since large ports are not needed for N/A power and flow. The combustion chamber on the 1.8 and 1.6L should be the same 43cc. That would raise the static compression of the motor. I'm not sure what the chamber volume on the SOHC heads are, but someone on here has stated that the SOHC 4G64 block and DOHC 4G63 head= 11:1 compression. That should be plenty high for a street N/A car. The pistons and rods will definitely hold the power you'll make. I'd like to see that done personally.

However, if you go turbo, then you'll want to build the bottom end at least a little. Some Weisco (or any brand) pistons on the stock 6-bolt rods should get you a reliable 400+hp engine. On the 2.4L you might think about longer rods if you plan to race with it to decrease the piston speed a little. You'll likely want to rebuild the head no matter what. If you run the 1.8L 43cc head, you'll need to compensate for the small boost in compression with any pistons you get.

With aftermarket pistons and rods, you should be in the neighborhood of a 600hp short block. Once you decided to build the short block, the head rebuild is a must. If you leave the lower end alone, the head should also work fine. Stock springs and cams can get you near 400hp, but I don't know of anyone who's gone that far with them. Usually 300+ means it's time for new cams. If you go N/A, you'll need some no matter what.

Do some digging and find people who have made power with the 2.4L before you do anything. You might try talking to experts like Magnus and Slowboy Racing. I don't deal with companies like that, but I'm sure they have a wealth of knowledge they might be willing to share. You can also contact Jack McGee of jackstransmissions.com. He's an awesome guy and gives free advice. Has tons of experience with odd engine combos and some new tricks he has.

Decide what you want to do and make sure you do your research.

Jed118 · Post by **Jed118** » Wed Oct 29, 2008 10:26 am

The head will receive complete treatment (3 angle, shave 0.030, port + polish) anyways. I want to pull this mill apart to inspect it, and while it's apart, I'm gonna add new pistons. I have heard that the stock pistons and valves will create compression 13:1 for about 1 second, then the valves will bend from contact. If you look at the stock pistons, and the wiseco ones, the stock ones have a buldge, whereas the wisecos have a dish.

Rest assured, the car will never make more than 400HP: It's going to be a mean street machine, but not a race car.

I have YET ANOTHER pony that, in time, if it survives it's current use as a winter car, will receive the G54B - that will be my "go fast in a straight line" car, but that's at least 5 years away. Right now I want to start building this 4G64...

One more thing: Where to I get a flywheel from? Will a DSM flywheel work?

jeffball610 · Post by **jeffball610** » Wed Oct 29, 2008 2:39 pm

Yes, the DSM flywheel works. You just need to decide what transmission option you're going with. I think both the D50/MM and Bill's bellhousing options use the FWD flywheel.

Shaving the head will get the compression up even more, so make sure you talk to your source for pistons and make sure this is what you want to do. Have you decided on turbo or N/A yet? If you go turbo, go with the 1.8L or 2.0L head for the larger stock ports. (obviously)

Start a project thread on here so we can see your progress with the car. I'd love to see one of those sleepers blow away some V8 power. How much does the Pony weigh? Is it a solid rear axle or IRS? Fill us in on what this car can do.