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Discussion Starter #1
Hey folks,

I'm curious what the hive-mind thinks about the prospect of reducing the hood weight by grinding/cutting the bracing off of the underside of the hood? I'd really like to cut weight from my car (track-only) and the aftermarket hoods seem awfully expensive. I bet I could chop 5-10 lbs out of the hood with a grinder, but I'm curious if anyone else has been crazy enough to attempt something like this?

Thanks!

Dave
 

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Dave, I have a Sky Redline that I have removed probably 350lbs. from but have not touched the hood yet. I'm going to track the car next weekend and then plan to remove the AC compressor, condenser and the radiator cooling fan and shroud. Crazy uh?

Larry.
 

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I haven't done it to a solstice, but things might get interesting when you try and open it. It'll be a flexy-flyer with the bracing gone. Everyone one I've gutted has been not only a much more conventional size but was removed completely via hood pins when it was opened. You could practically roll them up and set them aside. Depending on how much work you want to put in, it might be a better idea to add some sort of louvers or venting that would allow you to completely remove the underlying hood in those areas and extract some heat/air pressure in the process.

Curious how your test goes Larry. I'm with you on everything but the shroud. These cars aren't known for their thermal robustness and there's a lot of stuff blocking the flow in and out of the radiator.
 

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Discussion Starter #4
Larry - that's a lot of weight! It should go really fast. I'm also interested in how the cooling goes since the last time I saw a GXP at the track it went into limp mode after three laps. I am considering pulling the AC as well...but what a pain!

Phil - yes, I would imagine hood pins would be necessary, and I'd pull the hood struts out as well.

Thanks guys!
 

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Larry - that's a lot of weight! It should go really fast. I'm also interested in how the cooling goes since the last time I saw a GXP at the track it went into limp mode after three laps. I am considering pulling the AC as well...but what a pain!

Phil - yes, I would imagine hood pins would be necessary, and I'd pull the hood struts out as well.

Thanks guys!
Not to hijack your thread but I think I will be OK with the temps. I have ran the car several days at the track with stock cooling system and never over around 222 deg. I think a lot of guys have some trapped air in the coolant system causing higher temps.

On the track I run at I will only be under 55 to 60 mph for one turn only and then only for 1 or 2 sec. Several straights were I will be 115 give or take. My theory is with the AC condenser removed I will get a little more air and the fan will be out if the way and the shroud gone will open up the entire rad. surface area, But I been wrong before.

Larry.
 

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Discussion Starter #6
Interesting! The day where the GXP overheated was around 90 degrees (Dominion Raceway) and it is a very tight, technical racetrack. What track are you running at?
 

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Interesting! The day where the GXP overheated was around 90 degrees (Dominion Raceway) and it is a very tight, technical racetrack. What track are you running at?

I mostly run it at Barber Motorsports track in Birmingham Al. It is a beautiful track and they have a Porshe driving school there. I go several times a year with the local PCA club. I love running with those Caymans. They just ran an Indy race there a couple of weeks ago.

Larry
 

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I reduced weight on a Fiat race car hood by removing the cross brace.

Sand blasted the underside of the hood to clean and reduce metal weight.

I bonded rigid styrofoam sheets to the underside, cut to fit between the cross braces. Once adhesive cures, cut the crossbrace out. The foam bonded to the hood will help retain the shape. I cut additional foam and filled in the void where the crossbrace was.

The Fiat hood was not as big as the Solstice's. The Fiat hood was probably a thicker, softer steel since it was not hydroformed. It was done in the early 70's.

If I did that today, I'd use a double cut structural foam core material (it's knife cut into small squares to conform to non flat surfaces), epoxied to the hood underside. You could press it down with weights but vacuum bagging would be best. Then cut out the crossbrace and fill in void. I'm not sure how much steel could be removed from the hood safely by sandblasting.

If the hood is still flexible, you could laminate a thin layer of graphite or carbon fiber over the foam and it would still be light and stiff and protect the foam.

That is a simple description and there are much more detail to the project but someone building racecars should have the resources and skill to tackle such an undertaking.
 

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On the track I run at I will only be under 55 to 60 mph for one turn only and then only for 1 or 2 sec. Several straights were I will be 115 give or take. My theory is with the AC condenser removed I will get a little more air and the fan will be out if the way and the shroud gone will open up the entire rad. surface area, But I been wrong before.
As long as you're maintaining ~15mph, higher speed doesn't really improve cooling much. (If you're really curious - the basic equation for heat loss is Q=hAT, with Q being heat loss, h the thermal coefficient, A the area, and T the difference in temp between the radiator and air. Air speed is irrelevant.)

You will get more air through the rad without the condenser and fan, but without the duct/shroud the air will want to spill around the edges of the radiator rather then go through it.

I absolutely love that you're trying something and having fun, but I'd be sure to bring that shroud to the track and be ready to re-install just in case. :wink:

And be sure to let us know the end result!
 

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Interesting topic

Personally I would not reduce the structural integrity of the hood as a safety concern. Its already pretty shaky.
 

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As long as you're maintaining ~15mph, higher speed doesn't really improve cooling much. (If you're really curious - the basic equation for heat loss is Q=hAT, with Q being heat loss, h the thermal coefficient, A the area, and T the difference in temp between the radiator and air. Air speed is irrelevant.).......
While airspeed is not directly relevant to heat transfer, air temperature is, and you need air flow to maintain a low air temperature. Zero speed (without a fan) obviously means no air exchange and explains why temperatures go up when standing still. Without the correct ducting to ensure airflow you can also get inadequate airflow because of turbulence or back pressure, and this can actually get worse at higher speeds.

Something to consider about modifying your hood: I know that aftermarket hoods are expensive, but I found a post (https://www.solsticeforum.com/forum/f59/looking-shed-some-pounds-70916/index2.html#post1070426) that stated Norm's is 30 lbs lighter than stock, so you would be much better off in that aspect. Add the fact that stock hoods in good condition are getting rare, and you could probably sell yours for enough to offset a fair amount of the cost.
 

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As long as you're maintaining ~15mph, higher speed doesn't really improve cooling much. (If you're really curious - the basic equation for heat loss is Q=hAT, with Q being heat loss, h the thermal coefficient, A the area, and T the difference in temp between the radiator and air. Air speed is irrelevant.)

You will get more air through the rad without the condenser and fan, but without the duct/shroud the air will want to spill around the edges of the radiator rather then go through it.

I absolutely love that you're trying something and having fun, but I'd be sure to bring that shroud to the track and be ready to re-install just in case. :wink:

And be sure to let us know the end result!
Phil, thank you for all the great input. And yes I will not take the fan assy. to the track BUT I also will not dispose of it till the testing is complete.

I follow you on everything except the air flow with the shroud removed. I thought the shroud was strictly to funnel the air to the fan.

I will be sure to post my results here. I plan to go next weekend with the shroud installed because I do not have time to remove it. This will be my 1st time back with the complete dash removed(heater, AC evaporator and blower.

I had to keep the little speed and tach assy to keep the data buss happy. I moved it to the center of the car under what was the dash.

Larry
 

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Sorry, I was imagining you were removing the ducting on the front of the radiator that scoops air into it, but after re-reading I think what you're actually doing is removing the piece from around the fan on the back side of the radiator.

I don't think that shouldn't cause any difference in cooling.

I'm not entirely sure what John is talking about. Keep it to sub-sonic, in-compressible flow and you'll be alright.
 

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I was imagining you were removing the ducting on the front of the radiator that scoops air into it, but after re-reading I think what you're actually doing is removing the piece from around the fan on the back side of the radiator.

I don't think that shouldn't cause any difference in cooling.

Yes, that is correct. I'm removing it to save a little weight but I believe more so to make the car easier to work on. Can't wait to get it removed. I removed so much at the rear of the engine on the firewall you can look down and see the top 2 tranny bolts to the engine

Larry
 

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Interesting! The day where the GXP overheated was around 90 degrees (Dominion Raceway) and it is a very tight, technical racetrack. What track are you running at?

I forgot to mention that I'm running a water/methanol injection system. This really keeps the temps down. The IAT (input air temp) is just above ambient.

Larry
 

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Hey folks,

I'm curious what the hive-mind thinks about the prospect of reducing the hood weight by grinding/cutting the bracing off of the underside of the hood? I'd really like to cut weight from my car (track-only) and the aftermarket hoods seem awfully expensive. I bet I could chop 5-10 lbs out of the hood with a grinder, but I'm curious if anyone else has been crazy enough to attempt something like this?

Thanks!

Dave
If you're anywhere near Dallas, I have a hail-damaged hood you can have to try this out.
 

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Discussion Starter #20
Unfortunately I'm 1500 miles away from Dallas! I do like the idea of selling the hood to fund the purchase of a Norm's hood... How much do hoods go for these days anyway? The Norm's hood is really expensive (hence my interest in lightening the OEM hood).
 
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