Nearing the end of my now Turbo 3800 build in the '87 GT using Water to Air Intercooling. Got some ideas and need to know if this will work great or is it overkill and dangerous.... (Ps. I'm dead set on Water to Air, this thread is not about that)

First, little background.. Everyone knows over 80 MPH the front end gets very light from built up air-pressure, over 90 MPH your headlight covers can and will fly open! I found with the hood un-latched there was enough air flow to lift it almost 4inches at 70mph even with the air flowing over the hood forcing it closed! That's a lot of air flowing up, under the front end. I do not condone any of this for the record... Furthermore when I wanted to enjoy my 3800SC, I would intentionally un-latch my hood to keep more grip on the front wheels, it made a huge difference, felt so much more planted and controllable.

So a hood vent is 100% necessary in my book. But could it work better? I think so..

With the front trunk removed its obvious the issues.


1. Hood vent, vents the trunk area not where the most pressure is at the top of radiator in the nose...

2. Having very little space behind the radiator, creates an air-bubble that can block air from flowing through the radiator...

3. Trunk wall at the nose is nearly 3 feet of slightly angled wall. Then add another 8inches where the body drops for the cabin. Thats a lot of flat space to create drag, and lift.


What I propose...

1. Cut out some of this cross brace so there's less blockage behind the radiator, allows more air to escape through the hood vent, and allows a real shroud and ducting to be designed for improved cooling, and smooth air flow out the hood.

2. Fabricate ducting to surround the radiator plus heat exchanger, to catch air, flow more air with less drag, and ramp up the outlet so it exhausts more air out the vent for better downforce and less drag.

3. Mount solid sheet from bottom of radiator, over cross-member, and attach to cabin. Smooths air underneath, creates flat bottom for lack of a trunk tub, and drastically reduces surface area to cause drag and lift.

or


Doesn't seem to hard for the benefits as my car is stripped to nearly bare frame, the only thing I'd be wary is of cutting out that front support beam. I'm not talking about modding the bumper or impact beam, just enhancing the bottom feeder characteristics for a much better flow of air through the radiator, through the hood vent, and under the car. Thoughts?

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1987 Fiero GTX 3800 Turbo... My Build, ST3 Cam, Lowered, Wheels, and pics enjoy!https://www.fiero.nl/forum/Forum1/HTML/089483.html

You may be adding more venting than is actually needed to achieve your goals.....

I haven't had any over heating problems. I have a 427 dart block aluminum headed roller cam motor. It definitely creates some heat. I drilled some holes on either sides of the radiator compartment into the wheel wells. I put in an aluminum radiator a little bigger (thicker - deeper) than would fit the stock mounts. I made mounts that fit the bigger radiator but still look stock from the top. I have the stock 87 GT fan. The car runs at 192 degrees under any conditions. I don't really think the Fiero is that tough to cool. Just my opinion.

Woody

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woodys 427

quote Originally posted by olejoedad: You may be adding more venting than is actually needed to achieve your goals.....

For now yes I'd agree. Being its my driver most of the time. However I'm building everything else ground up and either doing it all the way now, or setting up the foundation for the future. I want to keep this car for the long haul, maybe in 6 years its widened, longer, and making 1000hp and needs the extra flow. Fact remains I don't like the design, I think it could be better, and I hate half-asing. I know I wouldn't take full advantage of it yet but, I'd feel better knowing its how I want it. By the way I was not planning on it looking as huge as it does. Just notch out where that bump is to fit the shroud, and have a small duct directing it out the vented hood. I have to have room for the battery, and intercooler reservoir.

Venting the air over the hood instead of under is preferable. Especially to keep the nose down at speed. Here is a sneak peek at my chumpcars' front end.










That should keep the nose planted!!!!!

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ARCHIES JUNK IS FASTER THAN SHAUNNA'S JUNK
12.3 is faster than a 13.2

As much as I agree that a hood vent is necessary...

simple vents in the hood have proven to be more than sufficient at lowering air pressure within the front compartment.

Also, if you are mounting your turbo's intercooler up front, you are going to have some crazy turbo-lag...

quote Originally posted by DKcustoms: Also, if you are mounting your turbo's intercooler up front, you are going to have some crazy turbo-lag...

Not really. Mounting an air/air intercooler up front in a Fiero, without converting to a front engined car, is just not tenable. The air pipes are just too big to run. The only real option for a front mount intercooler is a air/water intercooler with a heat exchanger up front, where you only run the water lines, which can be much smaller than air intake pipes.

All just my opinion...take it or leave it:

I think your doing way overkill. I can see adding an intercooler if you want. My turbo 'Nascar' engine did not have one and it was plenty fast enough. It was in a Ferrari body kit that prob has some different aerodynamics. Originally it had the pop up headlites with just fake louver covers and I never saw or felt this front lift people talk about, even at over double the speed limits. My stock body Fiero V8 also never had the lift I noticed or headlite covers pop up either. It also never overheated. It felt looser at the rear end than the front. I dont think you can design pans and covers that are efficient unless you have a neighbor with a wind tunnel for testing. You may create more airflow problems than you fix. If you like innovation and experimenting, go for it.

quote Originally posted by DKcustoms: As much as I agree that a hood vent is necessary... simple vents in the hood have proven to be more than sufficient at lowering air pressure within the front compartment. Also, if you are mounting your turbo's intercooler up front, you are going to have some crazy turbo-lag...

My bad it was late but I meant heat exchanger not intercooler. I'm using a water to air setup with the intercooler in the back and just water lines to the front for an extra radiator like Dobey said.

Are you leaving the front tub out of your car? Removing it makes the problems worse, as you end up with an open area creating turbulence. I'd keep it in or build something to enclose the tub area in an aerodynamic way, to keep air flowing out and around the car. A small hood vent forward of the tub is more than enough to solve the pressure issue that causes the headlights and hood to lift. You want the hot air going up and over the car, and cool air going under the car and into the engine bay and over the exhaust, to keep temps down in the rear as well. Even with the air/water IC, the turbo itself and exhaust manifolds are still going to get quite hot, being able to contain the heat and cool them down with air flow will help.

quote Originally posted by dobey: Are you leaving the front tub out of your car? Removing it makes the problems worse, as you end up with an open area creating turbulence. I'd keep it in or build something to enclose the tub area in an aerodynamic way, to keep air flowing out and around the car. A small hood vent forward of the tub is more than enough to solve the pressure issue that causes the headlights and hood to lift. You want the hot air going up and over the car, and cool air going under the car and into the engine bay and over the exhaust, to keep temps down in the rear as well. Even with the air/water IC, the turbo itself and exhaust manifolds are still going to get quite hot, being able to contain the heat and cool them down with air flow will help.

I guess I haven't decided yet, if I was leaving it out I'd put a big flat sheet to make the car flat under the front, minus the opening and ducting for the bottom feeder radiator flow... And yeah that was also my thoughts, I figure the smoother the air under, the more will reach the rear of the car, again already the air flows up and out the vents, but with added ducting I'm sure it can be better. My Turbo setup is a top mount over the transmission, and the turbo is placed almost directly under the drivers side vent. Along with easier brake cooling, I think making the front end smooth, will definitely benefit the rear. Along with actually channeling airflow out the vents, which should be a lot less resistance, much greater flow, and hopefully more traction... My 3800sc hit a "Wall" at 130MPH it didn't want to accelerate, felt unstable, and was scary... I un-latched the hood, and immediately the car felt more planted. It then got up to 152mph (GPS)