I'm updating my induction on a Fd3s twin turbo automatic and I'm wondering what is the best kit. Ive been told that the Apexi pipes and filters have come out on top of a number of tests. Has anyone got experience in this area?

 

Back when I didn't know any better, I bough the Apex'i intakes for my FD. I'll go on record stating that the Apex'i intake system was a huge waste of time and money. Yes, the filters themselves may have a better-flowing internal anti-induction-turbulence design, but that's only part of the equation. The overpriced intake system turns your stock cold air intake into a hot engine bay air intake.

fwiw, the GReddy Airinx intakes are similarly engine bay air intakes, but the low-restriction filters and smooth mandrel pipes do help air flow, and the turbos *felt* like they were spooling slightly faster than with OEM intake. At any rate, it felt like a slight improvement at best.

Overall the intake that gets the coldest air into your engine is the best intake for power, fuel economy, and engine longevity. You can save your money by drilling small holes in the bottom of your intake box with a drill and hole bit. This makes it easier for your turbos to suck in *cold* air from under the intake box, and if you already have basic tools, it's a free mod.

For less than the cost of hot air intakes these days, every performance measurement is improved with a Koyo radiator. The only two downsides are 1) you need to drill two holes (one next to each stock Koyo mounting hole, takes 2 minutes max) to get it to sit slightly lower in the engine bay (to allow the stock IC duct to fit), and 2) you'll notice your heater won't blow as hot afterwards.

 

Something along the lines of the old M2 intake boxes were, I believe, the best at sourcing ambient air rather than air from under the hood. M2 no longer exists as a company, but SR Motorsports' design is very close in design and also take K & N rechargable filters. http://www.srmotorsports.com/sr93intk.html
I'm not sure what shipping to Great Britain would cost, but it gives you an idea of what I'm talking about.
Those open intakes will provide less restriction and in a cooler climate or at higher vehicle speeds you might not see alot of performance difference. Especially if you ran a vented hood. But ideally sourcing air from outside the engine bay is preferred.

 

Occasionally those M2 air box kits pop in the classifieds across the web. Might be worth looking into unless you make your own.

 

M2 looks clean!

 

hks rs intake for twins

replaces ALL plastic pieces which crack easily. specifically the elbow that mounts to the front turbo

 

I believe I saw one in good condition on sale (3rd Gen Parts section) within the last week, and the seller is asking $550 for it. It's $600 + shipping new. Still a lot of $$$ for an intake, especially when you can simply mod your stock box as described in Post #2 ^.

^ So the suggestion here is to have the OP spend nearly $800USD shipped for two filters and a couple bent pipes that effectively delete the cold air induction in favor of one pulls hot engine bay air.

Furthermore the stock intake pipes are not plastic; they're rubber, which doesn't "crack easily." The one short elbow that connects to the primary turbo is plastic, but it is not known for cracking.

Here's a better way to spend $800, and give your 2 main weapons of induction a nice refresh:

Fritz (excellent seller and well-known on the forum) is currently selling a set of low miles twin turbos for $750 +shipping here (Post #123):

https://www.rx7club.com/3rd-generation-rx-7-1993-2002-parts-99/pfc-re-v-mount-rea-hls-fuel-kit-oil-cooler-kit-etc-937968/page5/

 

I didn't suggest how much he pays for them, but he asked what the best was. Thats the one that completely replaces the stock parts, reduces the connections, and even looks pretty good as well.

This is my opinion of course, since all three of the last plastic elbows I saw in person had jbweld all over them because the nipples broke off and the cracks propogated.

I am also a big fan of the 99 ypipes and any other kit that increases the durability of the system. Last thing I want to do is troubleshoot an entire turbo system when i can eliminate half the fail points from the start.

Also, it can be argued that cold air induction on a turbo car produces insignificant results. I won't argue it, but I will suggest making a box out of household flashing. Same form and function of store bought boxes.

I will also suggest refreshing your turbos if you can. Mine have 155k with no major overhauls because of routine maintenance.

Oh, and I can pee pretty far too

 

If by elbow you mean the long elbow that attaches to the throttle body, that nipple is often eliminated and JB welded when people remove the emissions related recirc hose that plumbs some post TB air back before the TB.

If by elbow you are referring to the the small little 90* at the inlet of the primary turbo, they don't actually break as often as you allude to. They do get brittle over time but mine is original from 93 with 153k miles and lots of track time and still in one piece and solid feeling. Hope I didn't just jinx myself....

I do agree though that a lot of the OEM plastic parts do eventually get brittle from heat and crack. Especially the pipes to the stock IC and sometimes the intake tubes to the turbos.


We all are.

That is an argument that we've had here on the forum for ages. It often turns into a pissing contest. However, it is proven that if you start with cooler air pre-IC, you will end up with cooler air after-IC.

Making a box to try and isolate the filters underhood in a suboptimal location doesn't help as much as locating the filters closer and in the direct path of a colder, fresh air source. That is why most people suggest the M2 style cold air box - it works.

Another option is cutting out part of the bottom of the stock airbox and ducting some air to it. I ran that for a long time and enjoyed it. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/cheap-stock-airbox-mod-121491/

A lot of that depends on how much boost you run, your EGTs and how often and how hard you track the car. My 40k mile 99 spec turbos had large cracks in the exhaust housings when I inspected them. I was surprised as they boosted perfectly and didn't smoke at all. LOTS of track miles on those puppies.



No need for that. This isn't a contest.
no, I'm not picking on you either. Just trying to share other perspectives and history.

 

haha, thanks gracer. good tips

just trying to lighten the mood around here.

 

Mission accomplished

 

just remember the old saying..... you get what you pay for.... so a little research figure out your funds and go from there. personally HKS has always been good to me. but idk about FDs.

 

FWIW, the 99 spec (often called the efini 'Y' Pipe) does eliminate one of the OEM rubber couplers, but it also flows better too. Put the old 'Y' section up next to the efini and you'll see what I mean.

You can modifiy the stock airbox to source ambient air and keep it from scavanging air from the intercooler. For the cost of putting a K & N in, it will perform as well as just about any open intake out there.

 

Do the cheap bastard intake mod. Best bang for your buck.



John

 

Anyone got a M2 or the SRmotorsport intake box? I am a mechanical engineer and if I can borrow one, I can reverse engineer it and make some drawings and machine a few.....