Water-to-Air Intercooler vs Water/Methanol Injection

[polizei]

So I'm still a few months away from starting the next phase of the turbo conversion on my '87 Carrera, and I'd figured I might as well kick this topic around and hear what you have to say. I've been planning to go with Water/Methanol Injection (WMI) on my turbo Carrera due to space limitations under the stock Carrera whale tail. There are a number of other folks on the forum who have successfully installed it, and they have reported great results. Sure, there are plenty of nay-sayers, but that's the case with anything that's not 'the norm'. It sounds like the bottom line with WMI is that you need to have it installed correctly with all the fail-safes to ensure that your engine doesn't go kaboooom!

I've recently been looking into the alternative of water-to-air intercooling (WA I/C). It's been suggested to me many times, given the constraints of my wing. I've searched this forum to find other folks who are running WA I/C. There is a fellow from Norway who I've reached to for more info, but not many others. I'd like to discuss the pros/cons of WMI versus WA I/C. Let's leave air-to-air intercooling out of it for this discussion.

WMI Pros:

1. Doesn't add very much weight
2. Highly effective at reducing detonation
3. Highly effective at cooling intake charge
4. Does not add any turbo lag

WMI Cons:

1. Requires frequent refills (depends in part on how large your reservoir is)
2. Requires fail safes surrounding fluid level, injector flow & general system operation
3. Methanol is corrosive to aluminum

WA I/C Pros:

1. Highly effective at reducing detonation
2. Highly effective at cooling intake charge

WMI Cons:

1. Adds more weight than WMI
2. Adds turbo lag
3. Requires installation of radiator - potentially cutting up front valance

This is just a conversation starter. There are plenty of smarter folks out there. Anxious to hear your thoughts.

[cole930]

Andy,

I have a 930 so I already had the IC and Tail when I started looking for how I could best prevent detonation and keep things cool.

When I first started looking I was going for just a water spray bar for the existing IC. I looking around it seemed the spray bar route used everything in the WMI system so I started reading. All in all the WMI is a simple easy to install system and the benefits were substantial.

I was really trying to look at it objectively and actually decided my parameters were going to be. Reduce heat, prevent detonation, easy install, reasonable price,
proven technology, and ease of maintenance.

Of all the alternatives I investigated WMI was the only one the covered all the parameters and also had additional benefits.

Also noted the research all pointed out that WMI was an significant benefit to turbocharged cars, the best alternative to an air to air intercooler,
and a must for the non intercooled 930.


Cole

[polizei]

Thanks for the reply Cole. There's no doubt in my mind that WMI is an excellent approach, and in all likelihood, I will be moving forward with it.

I'm really interested in hearing feedback from folks that have taken the water-to-air i/c approach, as I haven't heard of many on Pelican who have gone down that path. I've been reading up on the topic, and it sounds like it's a tremendous alternative for folks with space limitations or for those who are on more of a budget. And it seems that the radiator placement could be done in a rear wheel well or on the underbelly, making it much less expensive/difficult than running lines to the front of the car and hacking up the front bumper/valance.

For $300 silicone intakes sells a kit which "supports 600 HP":

Water to Air Intercooler

Sure, there's plenty of reason to be skeptical, but for $300... I'd be willing to pioneer that!

Thoughts?

[WANNA930]

Not sure of the heat generated between a supercharger and a turbo but they are widely used by the Mustang crowd. I have a 03 Cobra engine in a street rod and the parts are not that expensive.

If you use an OEM pump such as the Mustang I think the reliability issue would be taken away as it is a proven part. Afco will make any size radiator or exchanger you want and are probably the best money to quality part out there.

I have a 77 with the different tail and agree it looks like a good alternative. I would also think removing a full width intercooler would free up some heat from the engine itself?? I think the Porsche guys tend to stay away as it is not the "Correct" looking way to do it and would hurt resale or how someone views the cars quality.

Guys and gals are used to looking at big intercoolers and saying "Wow" but that doesn't mean they are the best way to go.

[jly535]

I'm running a W/A intercooler setup in my turbo BMW. I had serious space constraints so it was the best option. I have a 77' 930 so I need to do something with it also, I'm leaning towards water injection for a easy application.

[polizei]

This is great information, guys. Please keep it coming!

Does anyone have data about pre & post temps with respect to a water-to-air i/c?

Also, any pics of radiators and Water-to-Air I/Cs fitted to 911s?

[wjfk32]

Greetings:

I have been following Cole's project and now yours in interest. Have you considered speaking with AWE/Porsche. Maybe they can give you some free advise or just passing by their shop. I would, its worth a shot.

Good Luck!

Walt

[polizei]

Hi Walt,

Thanks for your interest! These are helpful topics for folks like me with space limitations or for guys like Cole who like to tinker and are just looking for some added safety.

I never heard of AWE before, but they're not that far away from me. I definitely need to check their shop out. I'm planning to work with Adam Hennessy of Rennessy Fabrication. Adam's got loads of experience with WMI on Porsches, but I haven't yet chatted with him about water-to-air ICs. I'm sure he'll have some valuable input. At this point, I'm tempted to install both "while I'm in there".

[wjfk32]

Andy-- A little info on these guys. These guys are on 6speedonline. I think they are right in your neck of the woods. I have no affiliation with this company.

If you think its hard to get info today and answers. I remember the 80's... Wholly Molly.


Walt


Tech Line: 888.565.2257 - Todd-Owner

via Fax: 215.658.1877
via email: sales@awe-tuning.com
Address: 2385-C Maryland Rd., Willow Grove, PA 19090
Hours: M-F 9am - 6pm EST

[polizei]

Thanks for the info, Walt. They're just down the turnpike from me!

[polizei]

I spoke with Gerhard at Bell Intercoolers, and he recommended two different core sizes for a 500 HP motor running at 18 PSI:

Decent efficiency --> 4.5x6x8
Excellent efficiency --> 6x6x5.5

I'm waiting to hear back from him regarding price quotes, but I'm considering a kit from silicone intakes with a core size of 4.25x5.5x10:

Water to Air Intercoolers

I like the positioning of the air inlet & outlet on this I/C, as I think it may fit to the driver's side of the throttle body, so I can run the charge pipe straight to it and then just fab a bend from the outlet to the throttle body. It looks like it should keep the air path simple:

[spence88mph]

Hey Andy,

The worst part is no one has really done any back to back testing, I guess it would be pretty hard to arrange. With water to air you would have limit space for a radiator and it would end up going in another compromised position. I think the best way would be an intercooler for turbokraft that fits under the lid like they made for someone else on here and a water meth kit for hot days or just to run as well... Maybe we can get a deal on 2 intercoolers

[polizei]

Originally Posted by spence88mph

Hey Andy,

The worst part is no one has really done any back to back testing, I guess it would be pretty hard to arrange. With water to air you would have limit space for a radiator and it would end up going in another compromised position. I think the best way would be an intercooler for turbokraft that fits under the lid like they made for someone else on here and a water meth kit for hot days or just to run as well... Maybe we can get a deal on 2 intercoolers

Hey Spence! Glad to have you joining the discussion. Yes, these two methods of cooling are not very popular options among the classic 911 crowd, but they definitely have their merits. As I've mentioned above, the constraint holding me back from an air-to-air unit is that I'd like to keep the stock look - no turbo tail. I've gone back and forth a bit with Chris from Turbo Kraft, and he mentioned that he won't fab air-to-air I/Cs for Carrera deck lids anymore - either with or without a whale tail. He says there's just not enough space to get an efficient one in there - not worth the money.

Chris installed a water-to-air I/C in a 993 Carrera a few years ago. The car was featured in Excellence magazine back in April '06. Here's the link to the build on Crhis' website:

Mike's 1995 Carrera 2 Twin Turbo "Sleeper"

Another fellow on Pelican installed a water-to-air unit on a turbo conversion with a duck tail. The I/C he fit in his engine bay has more than enough capacity for my HP goals, and I don't think I'd have any trouble getting one like that in mine. His build is here:

Watercooled intercooler system on aircooled 911

The parts are pretty inexpensive in the states for water-to-air components. The only electrical items to install are the pump and the optional fan for the radiator. Other than that it's just a matter of mounting the radiator & I/C and running the lines. If you've got the engine out, I bet this could be installed in just a few hours. Mounting the radiator is probably the trickiest part. I imagine that an efficient one could be installed in a wheel well, though. I believe Chris installed one in the driver's side wheel well for that 993:



For the price that these systems can be purchased, I'm thinking about installing both WMI and a water-to-air I/C. It should provide loads of cool air to the engine and relatively cheap insurance against detonation.

I'd just like to hear from more guys who have gone down this path!

[spence88mph]

That system looks great, I saw TurboKraft had made an intercooler for a 930 with no tail on the forum, I thought it looked pretty good... It's hard to believe those little water to air tubes could work on that project car, I'm sure they do though, Turbokarft seem to be a class act, looks like a lot of work and cost... I don't have a tail either and would like to keep it that way. I keep thinking about getting an interooler behind the rear wheel but not sure if it would get damaged easily and get enough flow.

I guess the best way is to start off with a before and after temp sensor and just experiment.

Did you see Juan said Eddie Bello was using a water to air on his car and the temps were getting too cold, would love to know how that system was set up...

[cole930]

Andy,

I have to give you kudos for your tenacity.

Cole

[polizei]

Originally Posted by spence88mph

It's hard to believe those little water to air tubes could work on that project car, I'm sure they do though, Turbokarft seem to be a class act

Having only one of those small ones would probably not be adequate - especially for a twin turbo. However, combining two of them provides around 1400 CFM of flow, I believe. This is definitely more costly than having one larger unit, and trickier to install. Fortunately for our cars, we have more room in the engine bay. Kjell from Norway fit this WTA I/C under his duck tail:

Originally Posted by spence88mph

looks like a lot of work and cost

It does on face value. This is part of what I'd like to vet out on this thread. There are a ton of places to source these parts for not a lot of money. The good thing is that there are several options for WTA I/Cs that will fit under our deck lids. All of the fittings, hoses, radiators & pumps can be had without much expense. I'm looking at a set up right now which would cost me about $450 which includes an I/C, radiator with high flow fan, upgraded pump and an installation kit, including fittings, clamps & fluid lines.

I agree - it does look like a big project. But I think that if the engine is out anyway, it would be a much less involved install.

Originally Posted by cole930

Andy,

I have to give you kudos for your tenacity.

Cole

Thank you!