Forged internals - shopping list help

[ChrisD]

Thinking about strengthening my engine so that I can increase the boost considerably, but I've never done anything with engine internals at all before so I'm looking for general opinions on what I'll need to strengthen/improve.

First of all, here's the relevant parts that I already have installed on the car:

• AVO stage 3 turbo (currently at 12 psi of boost in the highest map)
• 3 inch turbo back exhaust
• uprated fuel injectors and fuel pump
• oil cooler
• Helix clutch
• 600 bhp rated drive shafts (axles) from The Drive Shaft Shop

So what would you guys suggest doing to the engine before we up the boost further? Interested to hear your thoughts on the following:

• Carrillo con rods (seem to be widely regarded as being one of the best for rods)
• Carrillo pistons or JE pistons?
• 9:1 compression ratio or 10:1 compression ratio? Worried that 9:1 might be a bit low for off boost driving... lets be honest the stock engine is already pretty lacking low down in the revs, so I don't want to make that a lot worse if I can help it. But perhaps with a lower CR we can map the boost to come in sooner?
• Should I get stronger valve springs? One tuner I spoke to said really not necessary and one said it would be a good idea
• Stock crank ok? One tuner recommended going for the HKS 2.1 stroker kit and one of their reasons was that they had issues with the oil drillings in the stock crank (the HKS kit comes with its own crank)
• Stock oil pump ok? Found a thread on here from someone who did the HKS stroker kit and had a supercharger as well, and they mentioned that they upgraded the oil pump.
• Do I need to get new bolts for the cylinder head and main engine block? I've seen some ARP ones for sale but no idea if I'll actually need them or not.
• Stock oil sump pan ok? One of the tuners I spoke to recommended getting a baffled sump but then I found a thread on here where someone said it was pretty pointless in our engines.

I know there's a lot of questions there... no worries if you can only answer a couple of them. Any solid information from people who have experience with this kind of thing (even if its in other cars) will be much appreciated as I'll admit I'm a n00b (but that's one reason why I'm doing this... to learn).

[SPCorBUST]

Interested in these answers as well, in case I ever return to a C38 and more boost.

[wparsons]

These are all things you should be discussing with your tuner. Personally, I would run the highest c/r your tuner is comfortable with for the power levels you want.

Keep in mind that the more you drop the c/r, the more boost you'll need to run and the more lag you'll have. More boost = more heat.

Valve springs will depend if you want to rev higher or if you're running enough boost that the stock springs can't keep the valves seated. If you're already building the whole engine, I wouldn't skip them.

[olsonpg]

The Crawford BRZ has a fully built engine running some serious boost. I dont know if their details are up on the web somewhere. Maybe shoot them an email. My plan is to do exactly what they've done.

[ame="https://www.youtube.com/watch?v=oLP-HCcX9as"]The 450 HP Crawford Performance Turbo BRZ - /TUNED - YouTube[/ame]

[spitfire481]

Do valve spring for sure. These motors like to throw rocker arms through the valve cover when they float around on the rev limiter with stock springs. 10:1 is a good all around cr for e85 or 93 (or equivalent) fuel. Does the avo stage 3 have the slightly larger turbo wheel? I used to make 400/350 on e85 with the base avo kit at 18ish psi

[ChrisD]

Originally Posted by wparsons

These are all things you should be discussing with your tuner. Personally, I would run the highest c/r your tuner is comfortable with for the power levels you want.

Well like I said I have been speaking to 2 tuners about this, but as they're opinions sometimes conflict with each other I figured it would be a good idea to get general opinions from you guys as well. I'm not saying I'll just go and do whatever someone tells me on here, but its good to have more information and recommendations.

[ChrisD]

Originally Posted by olsonpg

The Crawford BRZ has a fully built engine running some serious boost. I dont know if their details are up on the web somewhere. Maybe shoot them an email. My plan is to do exactly what they've done.

Yeah I've seen that video before but didn't consider sending them an email. I'll see what I can find out about it

[ChrisD]

Originally Posted by spitfire481

Do valve spring for sure. These motors like to throw rocker arms through the valve cover when they float around on the rev limiter with stock springs. 10:1 is a good all around cr for e85 or 93 (or equivalent) fuel. Does the avo stage 3 have the slightly larger turbo wheel? I used to make 400/350 on e85 with the base avo kit at 18ish psi

Yeah this one has the larger billet turbo (they say approx 20% increase in flow over the stage 1 & stage 2). I think getting hold of E85 round here is a bit of a pain, so I'm just aiming for a good setup on super unleaded fuel (98/99 RON).

Thanks for the advice on the valve springs - that was what I thought I'd read somewhere else and why I was surprised one tuner said don't bother with them.

[jack43]

The elephant in the room is the stock tranny and its inevitable grenading in 4th gear.

[WHITE]

Carrillo rods are good.

Cp or JE are both good pistons.

10.0:1 CR

Yes to stronger valvesprings.

As for oiling, id look toward element tuning for suggestions as they're most likely leading the pursuit in better oiling.

The HKS stroker kit puts the rod/stroke ratio way less then ideal, increasing side load on the pistons.

Head studs would probly be a good idea, even if they aren't needed.

Case bolts you can probly skip over, however if you've gone this far might as well change them too.

[ChrisD]

Originally Posted by jack43

The elephant in the room is the stock tranny and its inevitable grenading in 4th gear.

Yeah I am slightly concerned about the stock transmission but I figure I'll see how far I can get before that dies... it seems to be pretty much down to luck whether or not you have problems with these transmissions as I've seen a lot of people be fine with high power through them and then other people have problems with hardly any mods at all. Forgive my ignorance, but if the stock transmission can't handle it then what options do I have? I can't find much info about swapping trannys on this car online apart from when people are doing engine swaps. Are there no other gearboxes that will fit on this car with the stock engine?

[ChrisD]

Originally Posted by WHITE

Carrillo rods are good.

Cp or JE are both good pistons.

10.0:1 CR

Yes to stronger valvesprings.

As for oiling, id look toward element tuning for suggestions as they're most likely leading the pursuit in better oiling.

The HKS stroker kit puts the rod/stroke ratio way less then ideal, increasing side load on the pistons.

Head studs would probly be a good idea, even if they aren't needed.

Case bolts you can probly skip over, however if you've gone this far might as well change them too.

Thanks - I'll see if I can get in touch with element tuning as well then (although they're not in the same country as me, but hopefully they're still willing to offer some advice)

[wparsons]

Originally Posted by ChrisD

Well like I said I have been speaking to 2 tuners about this, but as they're opinions sometimes conflict with each other I figured it would be a good idea to get general opinions from you guys as well. I'm not saying I'll just go and do whatever someone tells me on here, but its good to have more information and recommendations.

I would talk to the one that is actually going to tune the ECU for you. They're the one that has to deal with tuning it, so you'll want them to be comfortable with your setup and goals.

[Spartarus]

Below in red I addressed the points that nobody else has addressed yet, all the other advice posted above is good so I left the rest alone..

Originally Posted by ChrisD

• Carrillo con rods (seem to be widely regarded as being one of the best for rods)
• Carrillo pistons or JE pistons?
• 9:1 compression ratio or 10:1 compression ratio? Worried that 9:1 might be a bit low for off boost driving... lets be honest the stock engine is already pretty lacking low down in the revs, so I don't want to make that a lot worse if I can help it. But perhaps with a lower CR we can map the boost to come in sooner?
• Should I get stronger valve springs? One tuner I spoke to said really not necessary and one said it would be a good idea
• Stock crank ok? One tuner recommended going for the HKS 2.1 stroker kit and one of their reasons was that they had issues with the oil drillings in the stock crank (the HKS kit comes with its own crank)
  
• The HKS kit uses Nissan RB/SR bearings. Journals are only a very tiny bit bigger than ours. The crankshaft oil distribution problem is related to the way that oil is distributed to the crank from the block, and the HKS crank does not address this. There are 5 mains and 4 rod journals. Only 3 of the 5 mains feed rod journals via the crank. The middle main feeds two rod journals, while the others feed only one. The second and fourth main journals do not feed rod bearings; that is why they are smaller. That's why you're more likely to spin bearings 2 or 3 before 1 or 4. The HKS crank does not improve on this problem. The marginal increase in bearing surface area will be made utterly meaningless by the increased forces from a longer stroke, compounded by heavier internals. The increase in displacement is very small, and the price is insane.
  
• Stock oil pump ok? Found a thread on here from someone who did the HKS stroker kit and had a supercharger as well, and they mentioned that they upgraded the oil pump.
  
• There's only 1 available replacement, Reimax makes it, some people on the forum, myself included, are investigating it but there's no data yet, stock oil pressure gets scary low for high power levels when hot, but plenty of people have been fine without it. Choice is yours. That said, basic math says the Reimax pump should move a LOT more oil. Certainly can't be a bad idea.
  
• Do I need to get new bolts for the cylinder head and main engine block? I've seen some ARP ones for sale but no idea if I'll actually need them or not.
  
• stock head bolts are torque-to-yield and are not reusable. You will neeed to buy new ones anyway, just get the ARP ones and call it a day. You don't have to split the block to change rods, so I wouldn't bother with the mains.
  
• Stock oil sump pan ok? One of the tuners I spoke to recommended getting a baffled sump but then I found a thread on here where someone said it was pretty pointless in our engines.
  
• stock oil pan is fine, baffle is pointless, the engine already has a great baffle in the upper oil pan. There are people on this forum holding 1+G's in the corners, with 1000+ lbs of downforce and 325 non-DOT slicks and they don't baffle the pan. What does that tell you?