Internals for boost?
 

Hello all,

I've done some research on FI and it seems like the consensus is that the weak point is the rods. 300hp seems to be okay for alot of stock engines but it's still a gamble. I have the money to buy a JDL turbo kit which is around ~7k with a tune and gauges but now I'm getting cold feet because I don't want to gamble my engine blowing up.

I've seen many people on here build engines but I get lost on the terminology. If I wanted to build my engine to reliably boost 7psi @ 280Hp 250 tq what do I change in my engine? the rods and the heads?

TDLR; What are the minimum amount of things I need to change in the engine to reliably boost to 7psi ?

I have a 2017 Subaru BRZ

thanks you guys for input!!!!

If you can't afford to re-build a blown engine, how are you going to build one now?

My $.02 is if you can't afford to fix it, or give up your warranty, don't do it.

it seems he can afford it just doesn't know what exactly he would need to be safe, and replacing rods on a new engine is way cheaper than rebuilding an engine that has failed.

Could be. When people use terms like "cold feet" and "gamble" it makes me think a engine build would be a major expenditure. Just my "input".


If OP just wants to know how to build an engine, there are hundreds of threads.

:search:

I think he's just asking for the bare minimum, greatest bang for buck longevity upgrade. A lot of the people just end up upgrading almost everything while the engine is open.

Nothing. Spend more on a good tune.

PM me to order a JDL + tune.

Money's definitely a component for most, but some people also just don't like their engines blowing up while they're driving and leaving them stranded or losing out on track time. I personally would prefer that to not happen :bonk:

Hustla :thumbsup:

@evomike yes that's exactly my point, I have the money for the engine rebuild right now instead of putting it towards just a turbo I can build the engine now and then later on drop the turbo. Sorry my poor choice of words @Sapphireho and i've used the search button but a lot of people abbreviate what they have and it's a bit confusing.

Thank you for your input mike, I've been stalking you secretly in many of the threads you open here and on reddit and I know you you know what you're talking about just because how long you've been doing it and how many people you've helped haha :)

With these power goals no internals need to be changed? Just a very conservative and very dialed in tune?

Correct. I run up to 10.5psi with my stock 2017, on E85, which is far, far more stress than just 7psi on 91.

To give you an idea of the stress differences... take a look at this graph.

https://i.imgur.com/X3Dp3wV.jpg

Grey = stock 2017
Green = 91 octane, 7psi tapering to 5.5psi
Pink = E70, 7psi tapering to 5.5psi
Orange = E70 12psi tapering to 10.5psi

This is my car, which is tracked quite frequently, running a GReddy turbo kit with CSG thermal management, Delicious flex fuel kit, boost controller and tune, DW injectors and fuel pump.

yeah it's almost 100 ft/lb of difference on the flywheel

You sure know how to put someone at ease haha, that green line is EXACTLY where I want to be!!!!

When you say taper to 5.5 psi does that mean that the wastegate spring is set to 7psi but as you boost it loses pressure to 5.5 ? because I want this type of behavior

Correct, it holds 7psi for most of the RPM range, and starts to taper slightly up top.

This is mainly dependent on the wastegate and boost controller setup. I have a GReddy T518Z (GReddy specific version of a Mitsubishi 18g turbo), that results in that behavior. With the boost controller, I can, if I wanted to, force it to hold the boost pressure flat all the way up to redline.

Agreed 1000%. I’m making 365 to the rear and I don’t have any issues.


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