alexdimen

iTrader: (13)

I had been putting off the cheap bastard intake and fast acting Triumph m/c IAT sensor for long enough. While I was in there I also decided to modify my stock IC ducting by extending the intake into the bumper opening, blocking off the extra holes and adding new weatherstripping. I also riveted some 1/16 thick stainless across the upper part of the duct opening and behind the extended lip to hold the deformed plastic mouth open a little better. The plastic duct had collapsed somewhat, reducing the cross section that air could flow through.

Before doing the modifications I took my 2 thermocouples and measured delta T of my intake air (post IC - ambient).

Pre-mod @ 10 psi

Ambient: 90F
Delta T post IC cruising: +30F (120 F)
Delta T post IC WOT full boost pull, fully warmed up on street: +50F to +60F (140F to 150F)
Delta T post IC regular street driving after heat soaking engine off: +70F (160F)!!!

Post-mod (cheap bastard style intake + extended, shaved, and resealed IC duct) @ 10 psi

Ambient: 90F
Delta T post IC cruising: +7F (97F)
Delta T post IC WOT full boost pull, fully warmed up on street: +30F (120F)
Delta T post IC regular driving after heat soaking engine off: +30F (120F)

I don't know how this will work for track driving, but I am very happy with the IAT reduction. This isn't a ton of data, but the initial results are a pretty drastic improvement for the extremely low cost of these mods.

The most surprising result for me was the extreme heat seen in the intake after heat soaking with the engine off. My theory is that the stock intake was actually pulling hot engine bay air the wrong way through the IC. It wasn't until I got moving quickly enough with low enough loads for ambient air to finally wander through the intercooler from up front. Even after that, my cruising intake was still ambient+30F!

I am very happy to have picked up a few ponies and hopefully added some more reliability to the car.

My next step will probably be auxiliary injection in the form of a pre-turbo H20 sprayer powered by boost pressure (no pumps) and a larger SMIC.

Howard Coleman

iTrader: (6)

good move and thanks for sharing. quite a dramatic result.

howard

Novtec1

iTrader: (6)

Hum.... guess im gonna start working on mine too... nice job!!!!

adam c

iTrader: (2)

That looks pretty good, and those temps are WAY DOWN!!!!. Glad the Cheap Bastard Intake worked well for you

alexdimen

iTrader: (13)

Please do! As soon as I saw that heat soaked temp I thought of my poor engine being flogged after sitting in grid at auto-x! No bueno!

IMHO this should be addressed along side the other reliability mods. The stock intake/IC duct design is horrible and makes so many compromises!

Thanks. I appreciate your work on the subject. I ended up making my own tweaked version due to the sides of my CSF alum. radiator coming closer to the frame than stock. It was a PITA getting it to fit and I would have gladly purchased one if I knew it would work! Your threads and others were great inspiration.

alexdimen

iTrader: (13)

Another data point for this mod.

Autocrossed the car in 95 degree heat this past sunday and recorded the following intake temps:

Sitting in grid awaiting first run: PFC read 35 C so about ambient temp
First run: didn't get past 45 C so about +20 F over ambient
As I sat in grid I would pop the hood and shut the engine down after water temp dropped to 85 C.
The intake temp after re-starting the car was between 35 C and 40 C. Creeping up to 40 C as I did more runs and the engine bay heat soaked more and more.
My last (5th) run was my fastest time wise at 64.4 sec, but also my hottest as the intake temp read 55 C pulling into paddock.

So at the worst I was was +35F over ambient for an intake temp of 55C/125F. I'm happy with the results for autocross. I'll update the thread after I get another HPDE under the belt with the current intake.

arghx

iTrader: (3)

Just for a little context, when a stock engine is certified according to SAE method, the supply air (air that goes to the dirty air snorkel on a stock airbox) is controlled in the engine dyno lab to 25C with something like 40% humidity.

Typically these boosted engines in stock form will read between 35 (95F) and 50C (122F) as you get to peak power rpm at WOT during this official testing, with that 25C supply air. Here is a chart showing intake manifold temperatures (post intercooler) from published SAE certification runs:

msilvia

I've got a fully ducted GReddy SMIC and would kill for those results. Did an ~85 degree day (probably a lot hotter on the black sealed asphalt lot) autox last weekend and IATs were just a one-way ratchet up during each run. Once the car is warmed up to 80c+ water temps the IC has basically already heat soaked. Intake temps climbed to mid 40s before the first run just in the time it took to close the hood and sit through the line at start. Just kept getting hotter despite sitting with hood open and fans on between runs and pouring water on the IC. I think I was about 60c by the start of the last run. AI helps knock temps down DURING the run but intake temps get so hot so fast when the car isnt moving.

Is something wrong with my car? Could there be some reason my engine bay is throwing off more heat than it should? Water and oil temps are rock solid but intake temps are always sky high. My typical numbers are basically your "before" numbers in the original post but I have a ducted big SMIC, wrapped downpipe, etc.

I tried a cheap bastard style vented stock airbox and it did nothing to these numbers, so I'm back to the GReddy open intake.

Narfle

iTrader: (16)

The stock IC doesn't heat soak so bad because it's not all metal. He also extended the lip of his duct, something to consider.

alexdimen

iTrader: (13)

That's interesting to hear... I had assumed a better SMIC would automatically mean better intake temps.

Does your ducting only go to the IC or does it include the battery, intake, and AC receiver/dryer like stock?

I don't think I would be picking up nearly as much efficiency if it weren't for that extended lip. Stock ducting is tucked up so high into the front above the radiator that air has no reason to go up there! Ducting is only as good as the air supply forced into it, so I would try stealing some of that front bumper opening and giving some of that air to the IC. It's all about pressurizing that duct inlet.

The cheap bastard style intake was only added so i could isolate the ducting to the IC.

Sitting there with the engine off and fan blowing 80C air off the radiator up onto the IC/intake without any fresh air moving through the intake could cause some heat soak as well.

msilvia

Thanks guys. Fascinating thought about the stock unit being better with heat soak. Makes sense. But my big SMIC doesn't do much good if it's thoroughly heat soaked in most normal driving.

I have the pettit duct straight to (and exclusively to) the IC, but the pettit "snorkel" is small like stock and sits about where the stock one does in the bumper: high up and barely in the airflow. I'm sure extending it would be helpful.

You're probably right about the fans too. I figured they'd help, but they're probably just blowing heated air. Best move between runs might be to let the car cool the water temp down for a minute then just shut the whole thing off.