Cast Aluminum Intake
 

I wonder if this is a decent upgrade for the early cars over the late ones. I've done a lot of port matching and polishing over the years and I wonder if this is a decent idea? You can pick them up pretty cheap used, and the P&P costs me nothing.

If I felt really stupid, I could have it Extrude honed too? I'm trying to teach my son a few tips and tricks as we do this build, but if it's just not worth it at all, I'll find something else.

Not a whole lot (if anything) to be gained from the manifold swap, apparently.

These things breathe just fine. I would leave the top of the motor alone and concentrate on the header, tune and possibly e85 if it's available in your area.

As someone who likes to try things for themselves verses listening to the inexperienced echos of the forum, yes it can make a difference. I got what could be described as a mild "VTEC" like feel above 6k rpm that I was not expecting and witness increased MAF usage to redline. I was genuinely curious as only one other forum member had done it. Curiosity cost me $900+ all said and done. $350? for IM and $600 for the extrude-hone service. That was 4 years ago, I don't want to think of what it cost now. Personally worth it. But I'd image we are only talking about another 6-10hp here.



https://i.imgur.com/aNQe4oc.jpg

Who did you use to extrude hone?
I've been thinking about going the same route for months but it rises and falls in priority on a weekly basis.

If you could've verified 6-10 horsepower, that would be substantial.

have you looked at the power blocks?

now i'm a little curious what polishing/extruding would do with them..

I was tempted to do a legit comparo right before the switch to FI. But with time and 2 dyno visits, I would be super deep in diminishing returns personally.

https://boneheadperformance.com

OK - I could buy that on a supercharged motor it could be worthwhile. 6-10 hp sounds a bit optimistic, but *maybe*...

For an NA motor, though, I don't think it would see any significant gains - just not moving enough air to need more flow.


Wait - are you saying you felt there was a 6-10 hp gain NA up top with the Extrude Honed 2017+ IM?

Was this vs. your stock 2013 IM, or the gain from doing the Extrude Hone on the 2017+ IM vs. not Extrude Honed?

I couldn't see Extrude-Honing being useful on the Power Blocks. They're already very smoothly machined, and they match up to the port sizes pretty exactly already.

Sorry, meant to say extrude honing the intake runners in conjunction with installing the power blocks to drop the torque curve down the rev range

Thinking about this some more, let's say best-case scenario, all of the 5 hp peak gains for the 2017+ motor came from the change in intake manifold design (which I'd consider unlikely - more likely a combination of the intake manifold and headers, and probably more the latter), then picking up an IM to try would be worth a shot given that they're pretty cheap used. At $200-300, you're talking $40-60 / hp in that case.

Spending $600 US for another claimed 1 to *maybe* 5 horsepower at the very peak of the rev range only through Extrude Honing doesn't seem worth it though, at $120 - 600 / hp.


Playing devil's advocate, though, let's say the opposite is true, and swapping the stock 2017+ IM nets zero gains (I.E. all the factory 2017+ gains come from the headers or something else), and you can gain ALL of the 6-10 claimed HP from Extrude Honing the manifold. The best-case $/hp proposition would be better ($60-100 / hp) and could also be compelling for someone like me with a 2017+ car to begin with, but I have a lot of trouble believing you'd see that big a gain (a 5% improvement in top-end airflow) from Extrude Honing alone unless the casting of the 2017+ manifold in stock form were really atrocious and actually choking the motor rather than just "not flowing optimally", and again, those gains would be just at the VERY peak of the power band in any case.


So, basically, what I'm saying is I could see swapping the IM being a worthwhile experiment for relatively little expense if you can pick one up used, but don't feel that Extrude Honing would be anything like a good value proposition for 99% of use cases aside from a maxed out, NA track build chasing every last peak hp or maybe for forced induction where you're flowing significantly more air.

Billet Power Blocks, for one, seem to be a much better bang for your buck to add usable NA power / torque, even without tuning (FWIW, I will be putting my car back on the local dyno to verify the BPB gains with and without tuning sometime later this summer).

Don't the powerblocks just shift the power curve down slightly?