WARNING --- TURBO NEWBIE
(but NOT new to fast cars)

I am building a 513cid Mopar EFI motor with twins, likely using s475's at this point. 3600# street driven car. I would like to have a "peak" target hp of around 1500, but don't plan on using that much on a regular basis. I really only want to bracket race in the mid to low 9"s but occasionally click off an 8.50'ish pass (don't want to install a funny car type cage in a street car). I am thinking that rather than install huge intercoolers for the target hp, I might be able to get by with some smaller units and use a nitrous system for additional cooling when I turn up the power.

I have seen intercoolers with N2o spray bars on the exterior to cool them, but I was thinking of just inserting a couple of nozzles in the tube between the throttle body and the intercooler. Or would it be better to just use an injector under the T/B? What about a nozzle at the compressor outlet to cool the air before the intercooler? If I'm using N2O do I even need an intercooler? Any Idea how much cooling one might get from a 50-75 hp N2O shot?

I already have boxes of extra N2O parts from previous toys, so I would rather use them instead of a meth injection system unless there are just too many reasons not to.

P.S. I take criticism well - constructive or not

Scotty

 

Run one decent sized intercooler, or a large air-to-water in the back seat.

I personally think that trying to use nitrous to compensate for an undersized intercooler is just a big pain in the ass.

What's your reasoning for not wanting to properly size your intercooler? You're going to add more weight to the car with a nitrous kit than you would with a larger IC.

 

Look into meth injection. more efficient than trying to use too small of an IC. thats all I use and the intake temps are in the 120 degree range. With your big cubes and lower boost, you will achieve your goal and with the meth you should see some pretty cool intake temps. you shouldnt need high boost to hit your target ET's.

 

Thanks for the reply!

If effect, I do want to run a "properly" sized intercooler, but 'm thinking, wouldn't it be better to run one(or two) properly sized for the 1000-1200hp which I hope to be running most often? Also being slightly smaller they would be easier to mounts and still keep the engine compartment looking neat. The N2O would be for the few "all-out" passes to try and make a few of the Q-32's or just to say "yep. its an 8.00 car".

I am not against a larger IC IF needed.

How big would an A/A IC need to be to support 1500-1600 hp???? Relative to 1000-1200hp????

Since it WILL be a street driven car, I don't want to have the issues of plumbing to the backseat for a A/W cooler. Also wouldn't it be more effort to have an A/W system (adding ice, draining it, ect.) than to just have a bottle I could turn on if needed? I have always had N2O systems in the past and find them practically second nature to install and use. I know the meth/water injection systems work, but the thought of purposely adding water in the motor makes me shudder! LOL

At 3600#-3700# I don't think the 30 lbs a N2O system will add would be a problem.

Scotty

 

I feel that you are correct, in that in reality I am only looking at 10-15 psi of boost to achieve my target HP, so an intercooler may not be absolutely necessary.

If the meth/water injection is used only for cooling, why would it be more effective than the N2O??

Maybe I am confused about IC sizing. My thinking is they are more sized for heat dissipation.
i.e. more boost=more heat= larger intercooler.

Would it be more correct to think that larger volume of air (bigger displacement motor) would need a larger IC for less pressure restriction. Or can a relatively small IC still have adequate air flow?

Thanks for the help guys - hope to figure this stuff out while I'm still young enough to race!

Scotty

 

i would also look into the water/meth..thats what im going to do on a 1000hp set up (far from you)..But the meth will last a lot longer than a bottle of nitrous and can be set to come on at any boost level and stay on until the boost drops..i think the water/meth will be better than a heat soked A/A after a few passes..

 

I think one intercooler is the only way to go anyways. Two intercoolers just make for more losses, more weight (more piping, more endtanks, more brackets, etc all add up), and I don't think they're nearly as efficient. I used to have a C5 'vette with a procharger, and even with an upgraded set of twin intercoolers it made quite a bit more power with a big single IC. Depending on the type of car your motor is going into, I doubt very much that you'll have any trouble fitting a rather large intercooler behind the grill. My Father has a 69 Roadrunner that is almost finished, has a 6.1L hemi bored/stroked to 426", along with twin BW S362 turbos. We haven't done the intercooler or plumbing yet but there should be plenty of room.

You're going to need a fairly large intercooler for 1200 or 1600 HP, but I still believe you should have enough room to mount a big guy in there.

I personally feel there is a lot of confusion over air-to-water intercoolers. Yes, if you're running on the track and want the absolute most charge cooling you should fill it up with ice. But an air/water intercooler with a good heat exchanger (Something like a half-size rad that you run the intercooler water through to cool it off a bit) will cool just as good on the street, IMO, as a big air-to-air cooler. But there is the added complexity you mentioned, you do have water lines that can leak, a water pump that can fail, the intercooler core could potentially rust through and leak, etc.

 

Nitrous does cool off the intake charge, but it's not as significant as you might think. And once the nitrous gets into the combustion chamber and the molecules split, you have a tremendous amount more heat and pressure. I don't think nitrous is the proper "fix" for too small of an intercooler. Meth injection is used mostly for the cooling, but it also adds octane, and once meth gets into the cylinder it continues to lower temps as it becomes completely vapourized. I think the meth is a great solution for trying to make a billion HP on pumpgas, but I think that for a motor that's only going to be set on kill at the race track I'd rather just pour in a tank of C16 and leave it at that.

You're on the right track for the most part. You do need a larger intercooler to suit your larger volume of air, but that volume of air is tied more to horsepower than to cubic inches. Look at a PT67 turbo, which flows about 75 pounds/minute of air. It can force that 75 pounds/minute of air into a 281" modular V8 as easily as it can stuff it into a 115" honda I4. Much differently sized motors, same airflow. You'd generally want to size your intercooler based on horsepower, rather than engine size. In general, intercooler flow is directly related to size. Yes, there are differences between tube/fin and bar/plate intercoolers, but lets not go there.

If I were in your shoes, I'd give up the guys at Bell Intercoolers a shout. They can tell you what you need for your application, and custom build you an intercooler with some nice end tanks that will be perfectly matched for your setup and expected power goals. I wouldn't be too worried about running too large of an intercooler either, I'm running a PTE "825 HP" intercooler on my Honda that is currently making about 450 WHP, and I haven't noticed any discernable difference in lag between this intercooler and a rather anemic Drag intercooler that was rated for 350 HP.

 

Personally, I would say go with the largest intercooler you can fit, and work with meth injection to meet your goals.

 

Not true - it's harder to get that much air through the smaller motor, putting you at a different P/R, and thus a different part of the compressor map.

X2 - dual intercoolers are for guys with extreme space limitations. There is a build sorta like yours going on in the MoPar forum - a 572" Chrysler with a PT101, done by a highly turbo-savvy guy. Check out the size of his intercooler....and maybe take down some ideas...