E85 NA engine build
 

Since my current engine is on it's half way to heaven i'm now planning my new engine build and got a couple of questions about it. Few things to know about my car:
- no street driving, track use only
- intake, catless header and full race exhaust
- E85 is always available so no need to switch between 93 gas and E85
- car has 90k miles on speedo
The things i'm interested in:
- are aftermarket fuel injectors and pump necessary or OEM are good enough for track use?
- OEM engine internals(pistons, rods, bearings) vs tune - pros and cons
I'll appreciate any help and sorry for my bad english :)

@Alarik

You should get the fuel starvation fix kit for track use. These cars can get left-hand turn fuel starvation. If you have race-car-like grip then you might have trouble with oil flow through high-g turns, but that's more for people who are sustaining 100+ mph on track through "lightbulb-shaped corners".

I don't think you need to do any engine upgrades. I think this engine is pretty reliable when being thrashed, just don't abuse it. On a NA car, you're more likely to have an injector seal fry from a bad e85 tune though, I'd worry less about this if your tuner is good.

If there is anything that should be upgraded, it would be the transmission mounts, subframe and differential mount. Those parts should be worn-in at that mileage. See the whiteline positive-shift and positive-traction kits.

For NA the stock fuel system has enough flow for E85, a tune is all you need. As Mentioned above, due to the shape of our fuel tank, starvation during sustained cornering can sometimes happen. Have a look in the Tracking sub forum for more info and possible fixes.

You didn't ask but I will mention it anyway, oil temp and pressure are an issue with our cars particularly in racing conditions. An oil cooler and oil pressure gauge are highly recommended.

If staying NA then just drop another stock block in. Do the fuel starvation, and oil pickup / baffling. an all out NA high rever cams heads etc.. would be awesome but so expensive for ROI. a FA24 swap I am sure is right around the corner if you can wait.
or
do rods pistons etc... and then add an FI kit.

Listen to this man. With a proper Tune, 93/E85 and a healthy block is the as much as you need. Stock Injectors are more efficient, and stock FP is fine. As others suggest:

Verus Flapper Mod for FP
Baffled Oil Pan
Oil Cooler
high quality 5w-30 oil with shorter change intervals

This 1000x. If I ever do an engine swap it's going to be the new FA24 with toyota D4S system. If it is anything like the K24 in my bros Si it is going to feel better than my full exhaust E85 NA FA20 build on his STOCK setup. Can't imagine how good the FA24 is going to feel with full exhaust, E85, and maybe, just maybe, a nice Jackson or Edelbrock SC kit. *Drools*

With a new engine, you might look in to the rocker arm retainers.

How competitive do you want to be? What is the racing class and limitations? What is your budget?

If you have a big budget then you could do a serious NA build. Stronger, but lighter pistons and rods with a higher compression would be good. Since you have E85, you could handle higher compression. Do ARP headstuds and King bearings. Do oil pan baffling/windage tray. There is an oil pump upgrade option. There is an oil pickup option to reduce the chances of cavitation.

Then work on the heads. Do a nice port and polish. Switch to some Ferrara titanium valvetrain, so you could raise the redline to 8k+.

Stock fuel injectors and pump is more than fine. Do the fuel trap door.

If you want to get crazy then there is more: destroke for revs or wait for FA24 for displacement, dry sump, sequential transmission, etc.

Don’t forget the supporting mods like changing your final drive or aero.

Has anyone ever extrude-honed the heads on an FA20?

Maybe but the heads flow more than needed as is. There was a thread where someone did an intake manifold though. Pushing paste ain't cheap

Can confirm extrude honing even just the IM isn't the cheapest mod but really its only the cost of a mid-tier header.. Effective, though definitely more mid range gains than top end where you have to do unpopular mods like larger a TBs to realize all the potential. Ive only seen one account from a guy that had port/polished and 3-5 angle valve job done to the heads. He said "it runs good!" in his F/S post saving for a K24 to replace it. haha

I’ve read that the TB can be improved, and the intake manifold flows fine, but the heads can definitely use improvement. The stock heads flow 265cfm per the article below. For comparison, I think the stock K20A2 flows 290cfm. A port and polish and the works to the heads should net over 300cfm. I think the heads aren’t bad, but like the article says, start raising the rpms and pushing things and more work to the heads is needed.

https://dsportmag.com/the-tech/educa...ylinder-heads/