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Water/meth inj + stock SMIC = enough on 10psi?

Old 09-05-15, 02:27 PM
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Water/meth inj + stock SMIC = enough on 10psi?

Random saturday musing:

So my car is full nonsequential running open hot air k&N cone filters, GReddy SMIC w pettit duct, PFC, exhaust mods, etc. tuned for 10psi. The stupid intake has IATs too high, so I'm working on putting back the stock airbox with both the IC duct snorkel and a duct to the opening next to the rad.

That will be a bit of a PITA bc the GReddy and stock box will be a tight fit and I'll have to cut a hole in the pettit duct for the stock snorkel. But I've also got the stock IC sitting around and I started to think how nice it would be to just go back to a totally stock engine bay. Of course, I know there's a reason people go aftermarket in the first place...

However, I'm planning in the fairly near future to throw in a very basic water/meth setup, untuned-for, as a cooling aid and detonation safety margin. As I understand it, having 25-50% meth in the mix should knock down IATs significantly. At that point, would I really still need a bigger IC for basic street/autox/track stuff at 10psi?
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Old 09-05-15, 04:55 PM
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Water injection works great with an SMIC. I run around 12psi and also have an intercooler water sprayer. My IATs will creep up at autcross between runs(maybe 56c max) then take a dive as soon as the water injection turns on.


I only put meth in the tank if there's a freeze coming. Water works fine on its own.
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Old 09-05-15, 06:55 PM
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Get cold air to the intake system. the size of the intercooler should be fine with the greddy as long as you get fresh air to it.

The biggest gains for our group when I tune cars is getting cold air to the intake filter and running a large intake filter.
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Old 09-05-15, 09:26 PM
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Yes it will be a tight fit. Yes it's good for use case.
Don't do the snorkel thingy. Get a AdamC cheap bastard intake. Your IAT's will be acceptable.
A small water/meth injection system will make you rock solid. 70w/30m(give or take) is a great start.
Do you have the fast-reacting IAT sensor? It's pretty key w/ PFC.

Last edited by Narfle; 09-05-15 at 09:28 PM.
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Old 09-05-15, 11:11 PM
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Water/meth inj + stock SMIC = enough on 10psi?

Originally Posted by lOOkatme
Get cold air to the intake system. the size of the intercooler should be fine with the greddy as long as you get fresh air to it.

The biggest gains for our group when I tune cars is getting cold air to the intake filter and running a large intake filter.
If the GReddy is fine, what about the stock IC? The root of my question is, for a mild power setup, do I even need an upgraded IC if I'm doing AI, as AI (at least with meth) seems to have such a dramatic effect on intake temps.

I agree about the cold air intake, by the way. It's sort of insane to me that people go to great lengths to upgrade the IC, then install k&n's in the engine bay sucking hoooooot air that makes any IC work harder and be less effective.
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Old 09-06-15, 05:13 AM
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Understand the differences between WI and AI.
Alcohol is good at absorbing the heat in the intake air. But to do that it needs some time to be in contact with that air. So if IATs are your concern, WHERE you introduce the alcohol/water mix is important. The farther up the intake track the better so it has time to do it's job. Lower IATs, some engine cooling, knock and carbon control. But IMO it will need a good management system, usually a larger reservoir and tuning.

Water is good at absorbing the heat from the combustion event (and reducing load on the engine's cooling system). Not as critical where it's introduced as long as it's evenly distributed w/a decent nozzle. Little affect on IAT but good engine cooling, knock and carbon control. Can be a much simpler management system (boost activated), smaller reservoir and not as likely to need tuning.

It's also not just size and IAT's but pressure drop to consider with the IC too. Personally I'd keep the Greddy IC and find a better intake. IIRC, the stock box (with a cheap bastard mod) will fit with it. Or there are other options, Pettit shield, and M2 style box etc.

FWIW, I run a PFS intake modified to source ambient air from the nose much like the Cheap Bastard, along with a PFS Medium IC. IAT's are decent. WI is introduced post IC/pre-TB. Reservoir is the WS washer tank. Other mods in sig.

Last edited by Sgtblue; 09-06-15 at 05:19 AM.
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Old 09-06-15, 04:34 PM
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Originally Posted by msilvia View Post
If the GReddy is fine, what about the stock IC? The root of my question is, for a mild power setup, do I even need an upgraded IC if I'm doing AI, as AI (at least with meth) seems to have such a dramatic effect on intake temps.

I agree about the cold air intake, by the way. It's sort of insane to me that people go to great lengths to upgrade the IC, then install k&n's in the engine bay sucking hoooooot air that makes any IC work harder and be less effective.
I don't have all the answers, but the car I tuned with non-seq twins and stock IC had very high intake temps. He was also running a lot of boost for this high of altitude, so that contributed to the high air temps. I would run the greddy IC and really focus on feeding fresh air to the intake and intercooler. he ran an ARC intake system.
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Old 09-07-15, 12:33 AM
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Originally Posted by msilvia View Post
If the GReddy is fine, what about the stock IC? The root of my question is, for a mild power setup, do I even need an upgraded IC if I'm doing AI, as AI (at least with meth) seems to have such a dramatic effect on intake temps.
Yes you need a new IC
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Old 09-09-15, 05:25 PM
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I'd like some insight as well. Seems like no one does this for a good reason or they just want more power. I seldom drive my FD and love it as is. I don't need much power I guess but would like to keep my IAT low without resorting to FMIC or VMIC I'd like to see if adding meth/water is beneficial in a stock car. I might add BNR's later on and a SMIC such as PFS
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Old 09-09-15, 10:40 PM
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Plus the stock ic is a huge flow restriction. You will have cooler intake temps and make more power with a better intercooler and meth injection. At the very least I'd get a used Greddy or Blitz stock mount and ad meth injection.
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Old 09-10-15, 08:03 AM
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Originally Posted by rxmiles View Post
I'd like some insight as well. Seems like no one does this for a good reason or they just want more power. I seldom drive my FD and love it as is. I don't need much power I guess but would like to keep my IAT low without resorting to FMIC or VMIC I'd like to see if adding meth/water is beneficial in a stock car. I might add BNR's later on and a SMIC such as PFS
I didn't do it for power. In fact I was mildly surprised when I didn't loose any noticeable power. As for "good reasons", my IAT's were OK with the aftermarket IC and intake. With the WI I've suppressed knock, controlled carbon to the extent that I'm comfortable pre-mixing with a working OMP, and added significant engine cooling. And I did that at relatively low cost, on the stock ignition and very little under hood clues that I even have WI.

Last edited by Sgtblue; 09-10-15 at 08:18 AM.
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Old 09-10-15, 08:15 AM
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Please don't use the stock intercooler. That thing wayyy undersized, made from plastic with plastic hoses. Its a joke.

Along w/ stock radiator.

Use a real intercooler, and run water/meth if necessary in addition. The standard aftermarket SMIC did great for my 13brew, with a homemade aluminum duct in front.

Last edited by Monsterbox; 09-10-15 at 08:17 AM.
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Old 09-10-15, 12:08 PM
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Regardless of the IC I would suggest isolating the IC duct so that the IC duct ONLY feeds the IC: not the intake, battery, or AC drier/accumulator. Extending the ducting down and forward to scoop in air with aluminum sheet also had a big impact on my intake temps.

Not suggesting you continue, but I'm running stock IC for now and haven't been able to get my intake temps above the 60's C all summer. That may change at a real track day with higher boost, but time will tell. I still plan to upgrade my SMIC regardless but there are other priorities now. That is without aux inj btw.
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Old 09-10-15, 12:41 PM
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Thumbs up

Originally Posted by Sgtblue View Post
I didn't do it for power. In fact I was mildly surprised when I didn't loose any noticeable power. As for "good reasons", my IAT's were OK with the aftermarket IC and intake. With the WI I've suppressed knock, controlled carbon to the extent that I'm comfortable pre-mixing with a working OMP, and added significant engine cooling. And I did that at relatively low cost, on the stock ignition and very little under hood clues that I even have WI.
Originally Posted by alexdimen View Post
Regardless of the IC I would suggest isolating the IC duct so that the IC duct ONLY feeds the IC: not the intake, battery, or AC drier/accumulator. Extending the ducting down and forward to scoop in air with aluminum sheet also had a big impact on my intake temps.

Not suggesting you continue, but I'm running stock IC for now and haven't been able to get my intake temps above the 60's C all summer. That may change at a real track day with higher boost, but time will tell. I still plan to upgrade my SMIC regardless but there are other priorities now. That is without aux inj btw.
DO you guys have any pictures of your setups and mods?
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Old 09-10-15, 02:47 PM
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Originally Posted by Narfle View Post
DO you guys have any pictures of your setups and mods?
Mods in sig. Pictures were replaced at the end here ---> https://www.rx7club.com/auxiliary-in...ion-fd-959565/
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Old 09-11-15, 12:13 PM
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Originally Posted by Narfle View Post
DO you guys have any pictures of your setups and mods?
https://www.rx7club.com/3rd-generati...temps-1070765/

Also look for the cheap bastard intake. And if you have a non-factory radiator note that you may have to modify the template or cheap bastard product a little as I did.

I made a template for the duct extender, but it is so simple you can just mock something up with cardboard and trim to suit.
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