Jerry
Jerry UberDork
7/12/20 4:11 p.m.

I checked the oil and gave it a once-over today before the first drive since I brought it home last weekend (1990 1.6)

It took me a second to figure out where the air actually made it's way into the engine, that plastic tube almost against the fender did not look very flowing.  I did a little looking online & found two that might be interesting:

K&N CAI on Amazon for $121 with free shipping.  Link

Racing Beat CAI on Goodwin Racing for $209 plus whatever shipping.  Link

I don't expect much, maybe a few horsies and more sound, heard a stronger pull around 3k RPM.  Should I just go cheap and Amazon it?

noddaz
noddaz UltraDork
7/12/20 4:22 p.m.

The corrugated tube may actually hurt air flow.  GRM did a test on this sort of thing.

 

CAI test

Keith Tanner
Keith Tanner MegaDork
7/12/20 4:28 p.m.

The RB unit is not a cold air intake, it's the opposite. But it will sound cool as it sucks hot air off the header. 

Check out the Randall Cowl intake. Actually works. 

rustybugkiller
rustybugkiller Dork
7/12/20 4:34 p.m.
Keith Tanner said:

The RB unit is not a cold air intake, it's the opposite. But it will sound cool as it sucks hot air off the header. 

Check out the Randall Cowl intake. Actually works. 

Cool!

ShinnyGroove (Forum Supporter)
ShinnyGroove (Forum Supporter) Reader
7/12/20 4:44 p.m.

This has been beaten to death on other forums, consensus seems to be that it's a waste of time/money except for the Randall which gives a very modest gain ( 1-2 hp) or one of those really cool intakes that has a turbo attached to the other end.

MrFancypants
MrFancypants Reader
7/12/20 6:12 p.m.
Keith Tanner said:

The RB unit is not a cold air intake, it's the opposite. But it will sound cool as it sucks hot air off the header. 

Check out the Randall Cowl intake. Actually works. 

Not enough airflow through the engine bay to keep the air near the exhaust down to reasonable or is that just a stagnant spot in the engine bay?

Keith Tanner
Keith Tanner MegaDork
7/12/20 6:38 p.m.

Not enough airflow and the exhaust just doesn't stop putting heat into the air :) That's just about the hottest part of the car, I suspect. Don't forget that any air in the engine bay was already pre-heated by passing through one or more heat exchangers designed specifically to transfer heat into air and operating at around 200F.

The RB also precludes the use of a shock tower brace, although depending on your personal beliefs that may not be a drawback.

MrFancypants
MrFancypants Reader
7/12/20 6:54 p.m.
Keith Tanner said:

Not enough airflow and the exhaust just doesn't stop putting heat into the air :) That's just about the hottest part of the car, I suspect. Don't forget that any air in the engine bay was already pre-heated by passing through one or more heat exchangers designed specifically to transfer heat into air and operating at around 200F.

The RB also precludes the use of a shock tower brace, although depending on your personal beliefs that may not be a drawback.

I think I'd just stay stock, if that were the case. I'd prefer to be able to add a tower brace and I'd also prefer to not have to cut new holes add an aftermarket intake.

Jerry
Jerry UberDork
7/12/20 6:55 p.m.

In reply to Keith Tanner :

You mentioned earlier that the vent on the headlight pod was useless for a stock intake.  Does that change anything here?

(And I'm thinking more air flow, vs temp.  That article mentioned go for flow first before lower temp.)

Tom_Spangler (Forum Supporter)
Tom_Spangler (Forum Supporter) PowerDork
7/12/20 6:58 p.m.
Keith Tanner said:

The RB also precludes the use of a shock tower brace, although depending on your personal beliefs that may not be a drawback.

I thought we weren't supposed to talk about religion on this forum. laugh

Fueled by Caffeine
Fueled by Caffeine MegaDork
7/12/20 7:02 p.m.

I had a racing beat one on my miata.. I can't speak to power gains, but I sure enjoyed the sound.

Keith Tanner
Keith Tanner MegaDork
7/12/20 7:14 p.m.
Jerry said:

In reply to Keith Tanner :

You mentioned earlier that the vent on the headlight pod was useless for a stock intake.  Does that change anything here?

(And I'm thinking more air flow, vs temp.  That article mentioned go for flow first before lower temp.)

If you can trap the cold air coming in through that vent, it's worthwhile. I used a similar setup on the Targa Miata when it had a certain intake design, and on one of my naturally aspirated Miatas I measured a double-digit drop in air intake temps by using the same intake setup used on the FM turbos combined with an intake in that area. But simply spraying air in through the headlight lid and hoping the intake catches enough of it is a bit of a crapshoot - and it will probably decrease the effectiveness of your radiator because you've just dropped the pressure differential across the heat exchanger by increasing the pressure underhood.

Temp helps. We've seen a 5 hp gain when dyno testing with the hood closed by pulling air from outside the engine bay vs pulling hot air from inside. The bulk of the intake was the same, so the flow was as good or better on the "hot air" setup. Most people dyno test with the hood open so you cannot evaluate an intake properly, especially a "cone filter on a stick" style intake.

KyAllroad (Jeremy) (Forum Supporter)
KyAllroad (Jeremy) (Forum Supporter) UltimaDork
7/13/20 9:05 a.m.

https://mossmiata.com/air-intake-system-by-cobalt

 

Most SRSBZNS autocrossers fab up a box around the air intake to keep that exhaust heat separated from the intake.  
 

Usually a bit like this one give or take depending on your fabrication skills.

Jerry
Jerry UberDork
7/13/20 2:07 p.m.

In reply to KyAllroad (Jeremy) (Forum Supporter) :

I like that one.  Looks like the filter might sit just behind the headlight vent.

Keith Tanner
Keith Tanner MegaDork
7/14/20 10:15 a.m.

It's basically what I had on my car back in 2002 - the FM turbo intake behind the headlight with a duct feeding it. There's no off-the-shelf kit, but if you start with one of these, add one of these and stick it to the AFM with an adapter (I know we have one but I can't find the link) you're close. You'll probably have to build a bracket to support the AFM on the front of the engine somewhere.

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