2G GHS- Project Engine Build Recommendations?

[gijoe985]

So, you can check our profile for more info, but our high school shop program is trying to get this 2g DSM back on the road. We got it not running with a bunch of mods. Right now, we're pulling the motor and planning on using the 6 bolt we had laying around. We have no 1g intake/exhaust parts, just the longblock. That said, we're thinking of putting the 2g head on the 1g block. Again, more in the profile, but with the holset hy356 and the 880 injectors, we feel like we're going to need to get forged pistons. Looking at getting some Weisco 8.3:1 compression pistons from ExtremePSI, unless we can get a deal elsewhere. Our block needs to be bored 020 over.

All that said, do you guys have any suggestions. We're trying to keep things on a budget. We're not planning, right now, to go crazy with this project. We would have done stock pistons, but felt like it would almost be bad taste to have all these mods with pistons that might break.

We're open to used parts. Just need to find stuff that fits our needs.

 

[bling5tatus]

A bad tune will break your pistons before that hy35 will. I'd stick with stock since you're on a budget and spend the money on a machine shop that is competent (good luck finding one, even among those that say they know 4G63 platforms).

I've never had forged pistons in any of my motors and never suffered a piston related failure. The turbo I'm using puts down more than that holset does.

Also, unless the car is set up for that holset already, I'd sell it and use something else. The hard parts required to get the "cheap" holset to work will overrun the cost of a nice custom turbo that would have much better transient response in a bolt on package. In any case, to each their own, if you love Holset then great but I'd spend some of the money saved in other places on an FP turbo.

 

[brane_97talon]

I agree with a bad tune breaking your engine before the turbo does.

Also, oil return supplies add up quickly for Holset turbos.

I would suggest getting a MHI stock-frame turbo, to bolt to a stock manifold and 02 housing... perhaps a TD05H 20G to go with your 880cc injectors.

 

[nwBryce89]

I would definitely agree with a stock frame turbo. What are your goals with the car? A 2g head will more than likely be more than enough if your not going ridiculous power, it also has better flow characteristics and can improve bottom and midrange. Your goals will also determine if you want to go forged rods and pistons you should be relatively safe under 500 with a good tune, but if it were me I would upgrade for piece of mind. A buddy of mine made over 630hp on stock bottom end.

 

[gijoe985]

So, the car is already setup with the holset turbo. They've got a modified manifold, the oil return is plumbed to the oil pan. So would I want to go through the trouble of putting a stock turbo on when this one appears to be good to go?

Any head gasket recommendations if we keep the holset?

 

[brane_97talon]

Got it...

If you dont NEED pistons, buy a nice intake manifold and intercooler with 2.5" pipes. Stock Fel-pro gasket should work unless a potato tunes your car.

What pressure you looking to run?

 

[gijoe985]

So, the car has a CAI and a FMIC with piping. We've not set a boost goal, but heard that the Holset can put down some good numbers, so we figured we'd plan accordingly.

 

[brane_97talon]

Ok, although Ive never run a Holset, Ive read that they live at 25+ psi. Any less and you may as well run a 20g and be quicker.

What will you be tuning with?

 

[gijoe985]

DSMlink V2. We'll need wideband. Don't have that yet.

Being that this is a high school, educational, project, the tuning is the part we are excited for. Trying to teach kids about the real "art" of working on cars. Not just bolting stuff on and praying for gains...

 

[brane_97talon]

Thats the spirit I wish I would have learned in high school, I was a late bloomer ha...

But yes. Definitely need wideband, and even though people think its old school, an exhaust gas temperature or EGT gauge. It would be good to research optimal air-to-fuel ratios for the type of fuel your looking to run.

And as a rule of thumb, I believe Aluminum melts at 1500 degrees, so 1200-1300 should be safe. Someone correct me if Im wrong...

 

[bling5tatus]

An important thing to note is that while this is a high school project and you're on a deadline to finish it..... if you rush/cut corners/short change/etc the mechanical assembly part you may not get to a spot where you can tune the car. EVERYTHING has to be in line before you can tune the car. This means no leaks and a healthy engine/transmission. That's a tall order for the inexperienced, but I wish you luck and I'm interested to see what you all come up with.

 

[gijoe985]

So, it we did try for 30psi, what head gasket? I would have guessed Cometic MLS, but now it seems that some people question their quality? Go OEM MLS?

 

[gijoe985]

Hey all, we're still working on this car. We got the aftermarket 2g pistons on our eagle rods in our 6 bolt block. Have a 2g head ready to drop on with arp head studs. Head was mildly polished (no real porting aside from just cleaning things up).

So, we went to take come measurements on our 280 cams that came with the car and there are some .010 differences between them. We weren't budgeting to replace the cams. Trying to determine a best course of action. We may run these until we can get new ones. If we get new ones we may settle for 272s. We want this car to be more for the street. Looking for something that works well with the holset hy35 we have.

Suggestions?

 

[91talonts1]

272s would probably be better for street use than 280s. I run a hx40 and 272s and they scream all the way to 9000rpm.

 

[jakelandry]

The injectors are your limit. Not to negate the work you've done or anything to that nature, but the forged pistons and rods were pretty useless as you would reach the limit of the injectors before anything else on that setup. you didn't say where the cams were .01 out. If theyre consistently .01 out on the lobes, theyre likely regrinds and just need shims or washers under the hla's to make up the difference. Provided that is the scenario, I wouldn't bother investing any money in replacing them.

 

[gijoe985]

The injectors are your limit. Not to negate the work you've done or anything to that nature, but the forged pistons and rods were pretty useless as you would reach the limit of the injectors before anything else on that setup. you didn't say where the cams were .01 out. If theyre consistently .01 out on the lobes, theyre likely regrinds and just need shims or washers under the hla's to make up the difference. Provided that is the scenario, I wouldn't bother investing any money in replacing them.

I did say at some point that we have 880 injectors. I figure those will get us a good ways.

And no, the cams have .010 difference between the lobes. Not evenly across. For instance I got 1.302-1.312 on the intake.

 

[jakelandry]

The 880's are your limit. I was implying that the stock bottom end could have handled any amount of power that an 880 cc injector can support. As for the cams, it seems logical to get something new. Once again, your injectors will limit your power potential so any cams will be sufficient. On a budget, I'd call up delta cams. They do regrinds for us very cheap.

I did say at some point that we have 880 injectors. I figure those will get us a good ways.

And no, the cams have .010 difference between the lobes. Not evenly across. For instance I got 1.302-1.312 on the intake.

 

[gijoe985]

The 880's are your limit. I was implying that the stock bottom end could have handled any amount of power that an 880 cc injector can support. As for the cams, it seems logical to get something new. Once again, your injectors will limit your power potential so any cams will be sufficient. On a budget, I'd call up delta cams. They do regrinds for us very cheap.

Ok, super helpful, thank you. Truthfully, our mindset was to sped a little extra time/money on the bottom end while it was all apart. New injectors are easy. Finding out we need new pistons in the long run would be a pain.

We have a walbro 255 ready to be installed. Once this whole things gets back together we're going to try to research where our bottlenecks are. I'm assuming that we'll have to upgrade a few other things before we'll reach the full potential of our 880s.

Anyone have a cam grind recommendation for our build?

 

[jakelandry]

Ok, super helpful, thank you. Truthfully, our mindset was to sped a little extra time/money on the bottom end while it was all apart. New injectors are easy. Finding out we need new pistons in the long run would be a pain.

We have a walbro 255 ready to be installed. Once this whole things gets back together we're going to try to research where our bottlenecks are. I'm assuming that we'll have to upgrade a few other things before we'll reach the full potential of our 880s.

Anyone have a cam grind recommendation for our build?

Their hks272 grind used to be the cam of choice cause there so streetable and require no degreeing or aftermarket valves, but they're a pretty dated design now. That being said, many people have made plenty of power on them, I personally say airflow of 63lb/min on a very inefficient turbo setup, and I think they go for a little over 200 dollars from delta so the price/performance ratio is pretty good IMO. They offer a billet kelford 272 grind also that will make a significant amount more power but will require upgraded valve springs to support the lift and ramp rate. Those go for a little over 300 I believe and since they come from a billet core, you may not have to shim the lifters. Those are just affordable options, there's plenty of others but looking at the nature of the build, price seems like a big factor.