OHV S/C install - Water/meth injection?

[arco777]

Have a Paxton SN-93 based centrifugal supercharger kit, going on my 94 Explorer. Current plan is to use a FMU that I have and save tuning for later, since there are no OBD-I tuners near where I live. Motor is all stock, auto trans so it won't likely be seeing over 4000 RPM. Number one priority is reliability. Number two is light weight and ease of maintenance/minimal added parts. Number three is power. This will be a low boost setup, seldom reaching 6psi. If I can run regular octane that would be even better.

The Explorer will be operated in a hot climate where it may see 110 degrees ambient temp during the summer. Since I am not doing tuning, and running the stock PCM with a FMU, I'd like to reduce the chance of ping/detonation and improve performance by reducing the intake air charge temperature.

I don't want to use an intercooler due to space constraints and weight. I have been looking at the water/methanol injection systems available from Nitrous Express and Snow Performance. Seems like for under $400 it would have the same basic effect as intercooling. Any input on this, or people who have successfully used it?

Another question would be which version of an injection kit to get. I am thinking I could get away with the cheaper kit which starts injection at a specific (adjustable) boost pressure, though for another $75 I could have a proportional unit. Any opinions on whether proportional injection is worth it?

Thanks!

 

[Dono]

I used snow performance, the one that has an adjustable start (low volume spray) and end (full volume spray), with different sized jets that can be swapped in.

It definitely helps cool the charge. The issue with straight on/off is that if you want to start spraying at lower boost (1-3lbs), the needs are different than that of 8-9lbs. This creates bogging when spraying too much at low boost levels. I learned this by playing around with it.

Also, if you can tune for 12 to 1 a/f and then use the water/meth to keep you at 11.5 to 1 you will get the benefits without making your mixture over rich. I could easily tell when I was spraying on my a/f gauge.

Intercooling is still the best. The issue with my ohv is that I get detonation when the motors hot, and its hot outside under low rpm/low boost situations. The air is just too hot, and Im not spraying meth at that level of boost. My experience was that in my application, I really need that intercooler so the air charge is cool all the time.

Hope that helps.

 

[arco777]

Thank you Dono, that does help!

So a fully proportional kit might be a better option for me? I noted the AEM kit is significantly more expensive but offers fully proportional injection rate with an advanced strategy. Perhaps that, or one of the MAF or MAP sensing proportional kits might work best for me as opposed to an on/off at X lbs of boost.

I wasn't aware that injection changed the AFR. Hoping to run as little injection as possible given my low power and boost level. I will be monitoring the exhaust with an AEM wideband with failsafe, and was planning to use the failsafe output to pull timing using the octane shorting plug if it got too lean. Any input on that?

Haven't experienced detonation enough to know what it sounds like or how to tell. Not even sure if my 94 has a knock sensor. What's a good way of watching for that?

 

[Dono]

You would know if you were hearing detonation. Kind of like marbles banging under the hood. Good news you are not having that issue. I think once my M90 gets hot, it's difficult to keep the iat's down. I'm going to try as cool of thermostat as I can find this summer.
I would save my money and not bother with it till you are having detonation issues. If your not tuning and getting detonation at boost after the install, try water/meth. It might save you some money on tuning and allow you to keep all your timing. If it's low boost levels your doing (2-4 lbs), don't be too concerned with the air charge getting too hot from being compressed.

 

[arco777]

Thanks, I guess I'll see how it does without it first. I used to hear a rattle underhood when pushing the motor hard, like uphill passing at freeway speeds, but premium fuel made that stop. Since then it has quit doing that on its own, even on regular gas. Never figured out why but it's been over a year.

Would running some sort of gauge off of the stock manifold air temp sensor be a good idea for monitoring intake temps? I do have an infrared temp gun I can point at things but would like a better idea of what the motor is seeing for IATs.

 

[Dono]

Yup, that rattle was detonation.

I don't know if you have an iat sensor on your year of motor or not. I know the electronics on your year is far different than mine, creating new challenges for you.

I was able to monitor my iat's thru data logging. It won't be so easy for you, I don't think.

Maybe check with jd4242. He will know if there is a air inlet temp sensor.

 

[jd4242]

I would use w/m just because of your climate. What type of charger are you using? If its not a roots then it should be very easy to IC and also it will naturally run cooler.really need more info.you do have a iat but how to splice into it and if a gauge would read it or not is a good question. You can buy a temp gauge and install it anywhere after the charger, closer to cylinder the better.I run a dual gauge so I can watch temps going into the charger and coming out

 

[arco777]

What type of charger are you using?

Have a Paxton SN-93 based centrifugal supercharger kit

I could install an intercooler if I have to but really don't want to. That's why I prefer the w/m if possible. Was going to put the nozzle right before the throttle body.

I'd like to get the truck tuned, but the only tuner I know of within driving distance was Henson and when I contacted them a couple years ago they were rude so I'm probably going to end up running without a tune for a while, just the FMU.

 

[jd4242]

You could do a air to air probably a 1/3 of the cost for w/m.plus you will always have to make fluid and if you run out you could be pushing it high in iat.w/m is more of a bandaid solution when front mount coolers cant be used, or last resort. But I would for sure run one of the two.

As far as tune.your need to purchase a sct eliminator chip and have it dyno tuned.anyone that can tune sct and 5.0 mustangs should be able to tune it.but with a fmu I wouldnt worry unless you wanna go past 4ish lbs