MADAZRX7

Hey all
Would like to know if any of you out there have used the ARC top mount for a S5 turbo? Am considering getting one and want to know what sort of gain (if any) i could expect with it.
I am not too keen on chopping the car and relocated battery as required with a fmic, but am looking for an easy mild upgrade. I only have stock computer (which will be chipped shortly) and running stock turbo with pod filter and full 3" exhaust from turbo back.
What is a realistic boost you can run with an ARC top mount? Am only running 9psi at the mount with a knightsports fuel cut defender.

Appreciate your thoughts & opinions on the ARC top mount.

Cheers
Andy

boostinfc3s

what other support mods are you running for that 9 psi you're cramming? From what I've heard its not much different from the stock tmic.

eage8

iTrader: (9)

the stock turbo's going to stop being efficient at around 12 psi.

the stock IC is fine up to like 10ish, the ARC is probably going to take you to 12, but not much higher. I would get a front mount, or just keep your boost at 9-10 psi, I don't think the ARC is really worth it.

Osirus9

iTrader: (10)

you should upgrade your fuel system before you pop your engine

dawicka2

Yup^^^.* I would study the hks style fmic set up and emulate that with an ebay universal 200.00 setup.* Spend the leftover money (today) on something to run 720 secondaries, especially with the added flow rate of the frontmount (depending on pipe sizing and exhaust ofcourse). Do some research, you can put a clean fmic together to your own specs for ***** cheap.

john ny

rotarygod

iTrader: (1)

If all he wants is an "easy mild upgrade", this is perfect. I've seen alot of myths about what you "need" and lets just say none of it is rocket science. Some of it is untrue however. On an 88 TII, I ran a stock engine with a full exhaust, no cat, with a fuel cut defenser and a boost controller set to 10 psi and it worked great. No detonation, no problems. I have no fear whatsoever about the stock fuel system's ability to keep up. It will at that level.

A top mount can be made to work quite well. You don't need a front mount to get good performance. Each system has their own problems and imperfections. I see no reason why a front mount is necessary with a stock turbo when a nicer top mount can do just fine. There just isn't any reason. Ultimately it's not going to be a huge performance gain but it will be something. I would take a stock turbo over 12 psi ever but that's just me. If you want more than that, consider getting a new turbo. The stock unit is capable of about 275 rwhp or so maxed out which is much faster than the 182 or 200 crank horsepower that the car had stock.

wackaloo13

iTrader: (3)

just get some alcohol injection

dawicka2

oops. he said s5.* I assumed by the fuel comments this car was an s4.* I am used to my s4 and my 5 pounds of boost. 9psi is far away... not for over 7psi s5s though.* I would still run a frontmount though. Saving even more money now that fuel isnt necessary.john ny

NoPistons!

iTrader: (3)

Relocating your battery should only take about 30 minutes depending on the trim level of your car and if you're doing it to track standards.

Upgrading the tmic probably isn't going to give you that much more of a gain. I mean, it's not like it could be any thicker or wider than it already is.

I'd just leave the stocker.

Turblown

iTrader: (12)

Some sort of water/alcohol injection would be a far better move than the ARC unit...

MADAZRX7

Thanks for all the comments guys.
I think for the time being i will stick with what i have and save some cash to do a proper job of the next upgrade - new turbo, fmic set-up, fuel upgrade. I think i will also look at going for a Microtech ecu changeover. I hear having this ecu change gives a lot more room for better tuning (as you'd expect i guess!) and performance gain even with stock set-up.
Cheers

rotarygod

iTrader: (1)

I'm going to start a huge debate here because I'm curious what the logic will be from some but I'm sorry to say that front mount intercoolers are over rated and sadly no one ever points out their huge drawbacks. It's true, now discuss.

Omixeo

iTrader: (1)

I wouldn't put a FMIC setup on with the stock turbo, it would create too much lag with very little gains. Depending on the core size of course, but it still creates more lag either way. V-mouts really are the best.

$P€€DD€VIL

I have an ARC TMIC too, ...but not on the car yet.
I don't wanted a FMIC because it's not necessary for my ~250hp plans.

cheesebox

can you measure the top-bottom height of the core? from what I hear it is a bit bigger?

prof

I've run the stock intercooler and the ARC unit with a hyrbid turbo (T04B 0.7 A/R front end) and had the benefit of being able to measure engine inlet temps with both running.

The stock intercooler will go to about 12 psi but at that point it's doing very little cooling. Heatsoak is awful, and the intercooler is a big flow restrictor.

The ARC unit seems to cope much better with the higher pressures - it ran at least 10 deg C cooler for the same pressure / ambient temperature, and more importantly, it recovers from heat soak much quicker than the stocker.

You need to change the throttle body inlet - the Greddy Compression tube works a treat - and you only need a 90 degree bend off that straight into the outlet of the ARC unit (which exits in the centre). I did modify the intercooler a little - I put a 60mm dia outlet on it - rather than the stock 56mm or whatever it is (it's easier to get an elbow that size ).

I've made close on 320 BHP at 12 PSI with it so far - my problem is the stock actuator spring is too weak to stay shut and leaks off boost - this was the side affect of porting the wastegate.

As for fuelling - with a walbro pump and a slight increase in fuel pressure the stock 550's took me to 318 with A/F ratio of 12:1 at 10 psi - injectors were hitting 89% duty. I've since upgraded to 800cc secondaries and this now sits at 10:1 with more fuel available for increased boost.

I do plan on using WI for the warmer days and higher boost - but the ARC unit looks like it will keep up nicely.

t24todd

iTrader: (7)

great info Prof..

$P€€DD€VIL

it's 7.5cm/ ~2.95inch thick

thanks for the info ! Because I bought mine without accessories,...only the IC itself.

Brody8877

iTrader: (10)

imo is not worth it

eage8

iTrader: (9)

how thick is the stock IC?

prof

Glad to share my findings.

This is the ARC unit in the car - bit 'involved' in the engine bay - I don't get marks for neatness - but the car is my daily driver - and some jobs end up waiting till I have time to do them more neatly.



You can see the outlet, and the elbow straight into the Greddy tube.

This car is Right hand drive - but from what I've seen there'd be plenty of room to do this on a left hooker too. The good thing with a top mount is there is lots of airflow for the oil cooler and rad.

I got the intercooler off ebay - but it had a split at the back where it had burst - although I repaired it with ally solder, I was never convinced and ended up getting it re cored - hence the 'ARC' label is missing off the front.

rotarygod

iTrader: (1)

Most people don't realize that you can drastically increase flow on a stock TII by modifying the intercooler outlet and tb inlet piece. The stock intercooler actually stays decently cool when there is airflow. Of course I'm talking about sub 250 hp levels. When sitting still it's a huge microwave though. I am actually a fan of a nice top mount. I think there are too many people that are against it purely because they don't "think" it can be as good as a front mount. There's far more to intercooling than just where it is located and far more to results than just guessing. There are some damn high hp WRX's out there with top mounts. There are only a few things that really matter when it comes to intercooling. Flow loss, area, and airflow. Location is irrelevant as long as those criteria are dealt with in an acceptable manner. I feel there is a lot of compromise in having a ton of extra pipe length, are, and bends to get to a front mount and it negates much of the benefits not to mention the heating of air before it gets to the radiator. Then again I can also argue the other side in favor of front mounts too!

I'd like to see more people pursue a good top mount design. I think it can really surprise people. Look at how much power 3rd gens can get with stock mount aftermarket intercoolers. While not top mount they are blasted on by the radiator fans and are inside the engine bay. They have a tiny amount of airflow by comparison to other locations and can still do pretty well in the power department. Hopefully this should at least get the creative juices flowing if not the creative opinions! Remember there are pros and cons to everything.

gxl90rx7

iTrader: (1)

Prof, can you post up what temps you are seeing with your setup?

Im running 15psi on a BNR hybrid through the stock IC.. in 60 degree weather im seeing about 75F cruise, but after a 15 psi run, intake temps are in the 130's F. Recovery to cruise temps is pretty quick though

I have cut some of the heat shielding away from under the IC for more airflow. I had a front mount on my old TII, same exact setup as now, the only difference being a streetported block. The intake temps on the old setup with a 20x9" fmic core/2.5" piping would actually drop in boost.

The other difference ive noticed is im able to hold a good 15psi with the stock IC. With the front mount I was only able to get 12-13 psi out of the BNR, i assume because of the pressure drop through the piping and IC. I cannot tell which setup makes more power (12 psi on fmic or 15psi on stock IC), but i may take it back to the dyno soon. It made 310whp at 12psi on the old fmic setup


I would love to keep the stock IC location, it look cleaner and you dont have to cut up your car. But intake temps scare me, but how high is ok? Im sure in the summer the temps will be even higher



i dont know if you guys saw this but take a look at this thread:
https://www.rx7club.com/showthread.p...rc+intercooler
anybody try removing the heat shield altogether? i tempted to tyr this now

SirCygnus

iTrader: (1)

I removed the heat shield. It works really well, but i dont have it logged at all. i did notice that it tended to cool off a bit faster when moving.

Trots*88TII-AE*

iTrader: (11)

BDC ran 25+psi with a 60-1 hifi on the stock topmount with mucho alcohol, and had intake temps drop below ambient. Obviously in the cooling department the intercooler was doing next to nothing (it was all alky) however, it did handle the pressure fine, I am not too sure what the pressure drop was, but it was not significant.