GOTHAM VETTE

Just looking for opinions from you pros whether a modification to the front of the frame in the manner depicted below will remove any structural rigidity from the car?

If so is it something that can be overcome, or are the gains in airflow, just not worth the hassle.

Solofast

WOW!!! That is a really really really bad idea!!!

I hope that isn't your car.

I'm assuming that the cutaway piece went all the way across the top of the radiator.

The torsional stiffness of the front half of the frame will be drastically decreased because of the much more shallow upper frame member. Stiffness of a section is a cube power of the height of the section. 1/3 the height = 1/9 the stiffness. You might just as well hack it all out, it isn't doing much good now at all.

Can you say "flexible flyer".... I knew you could!!!

Maybe you could get it back by triangulating the opening, but what that guy did was beyond dumb. Then again it looks like it's some kind of FI car since I'm seeing a bit of turbo, or radial compressor inlet in the bottom pic.

It looks like there's a big intercooler ahead of the radiator and that is what is taking up the space, and the reason for doing what he did. Still, unless he puts the structure back to get some stiffness back he's likely to have problems with cracking the front cross member where he hacked out the material. Remember that GM looks at the cost as a "by the pound" issue. They didn't put extra metal in there to make themselves happy. That decrease in section modulus is going to cut the stiffness of the front of the frame to nothing, and the flex is going to concentrate the stress where the cutout ends.

I wouldn't recommend tracking the car like that unless you replace the stiffness with a lower u shaped section that goes down in front of the bottom "tank" of the intercooler and then used a couple of thin pieces to triangulate the opening

travisnd

I've seen a few big FI builds do this. Probably better to cut it off completely and replace with tube steel like forum member rmakintosh did has part of his C6 build.

http://forums.corvetteforum.com/auto...it-begins.html

95jersey

The C6 already breathes so well that any improvement in airflow would outweight the negatives of cutting the frame. I mean how much HP would you really get...2-4 tops, that is not worth cutting your frame.

GOTHAM VETTE

Actually his images are what had me thinking that such a thing would be possible, specifically the one below.




My thoughts were that with the remaining factory structure, along with some additional tubing welded in (behind where the front frame would be in this pic) you'd be able to make up for the lost strength.

travisnd

I believe OP's car is a supercharged C5 that he's trying to make withstand HPDE/TT sessions.

GOTHAM VETTE

You got it

I also understand that there are other steps I can take before going down this route, just looking into all the possibilities.

travisnd

Best advice... sell the supercharger stuff and go NA. Even companies like ECS don't recommend superchargers to their road course customers. I just doesn't work well.... more parts, more heat, more weight.

Jason

Add full aero, coilovers and full carbon-fiber body panels. That's the only way to be fast.

Solofast

What would have been a far far better solution would have been to cut off offending cross member from the frame, twist it 30 or 45 degrees (imagine hinging it at the top and swinging it away from the cut line at the bottom) and then made some triangle side pieces and a flat bottom piece to weld back in to fill the gaps created by the twisting of of the cross memeber. Then you would have the same or just about as good a chassis from torsional basis, and you would still be able to get the air you needed.

travisnd

Oh snap I forgot... make sure you get one of those turbonator inserts for the intake track... oh and don't forget the Z-Max

I can't remember the guy's SN, but he had a beautiful Spiral Gray C5 that was supercharged. He tried every trick in the book to make it a track day car. He had a Tigershark nose and converted it to a front breather and a vented hood and big radiator and stand alone oil cooler etc. etc. etc.

He ended up building a pretty rad NA C5Z06 race car... I think he garages it at Autobahn Country Club with some of the other forum members who frequent that track.

AU N EGL

Removing the Supercharger will be a BIG plus for HPDE/TT

Then weld in a new cross fame piece.

travisnd

That's not his car... just an example.

DOUG @ ECS

Agreed if the owner is an avid track guy, we have many occasional HPDE guys that are supercharged and have a great time with it. You do need to learn how to drive the car a little differently then an NA build though. RPM's do not go as high, but you have the power to do what you need without reving high. That keeps the temps in check well enough for most HPDE F/I guys.

davidfarmer

Guys, I think you are totally overlooking the fact that the subframe adds a lot of torsional rigidity to the frame, and while I can't say I'd take that much out, I don't think any of us have the ability to say how bad it really might be

My real question is why? Unless you are building a custom nose with some sort of really open front, you don't need to cut that much out to get good airflow. Looks unnecessary to me!

RX-Ben

he should have left the frame, gotten an i/c with side tanks. Look how much fresh air is hitting the bottom tank.

nvygw171

on the sub frame part even though its bolted. Even still Throw a cage in and bam you have rigidity back + some! (race car). Street car with occasional hpde ignore all this.

GOTHAM VETTE

I can't remember the guy's SN, but he had a beautiful Spiral Gray C5 that was supercharged. He tried every trick in the book to make it a track day car. He had a Tigershark nose and converted it to a front breather and a vented hood and big radiator and stand alone oil cooler etc. etc. etc.

He ended up building a pretty rad NA C5Z06 race car... I think he garages it at Autobahn Country Club with some of the other forum members who frequent that track.

[/QUOTE]



That was Tom Snitz, his car was built by EPP, in post #42 in the attached link you'll see that he was able to run hard throughout entire stages with his blower.

http://forums.corvetteforum.com/c5-f...-f1-vs-d1.html

GOTHAM VETTE

Doug has hit the nail on the head.

My car is primarily my weekend toy and drivin on the street.I've started to do some HPDE events but am certainly not competing on any level. My goal is to set up my car so that I can drive it as hard as my ability allows me to when at the track (maybe 5-6 HPDE's a season), and not having to coast around halfway through the session.

What I'm trying to accomplish this winter is to improve the efficiency of what I've already done to the car.

- Dewitts rad
- External oil cooler, (although I'm going to me moving it shortly to try and remove it from the path of air to the rad to avoid preheating)
- ACP vented hood
- Straight distilled water with water weter
- Converted to front feeder (see below pics) I've pretty much opened things up as much as I can with the factory nose, if this still isnt' enough to provide sufficient airflow then I'll look at switching to the tiger shark. (The splitter in the picture was completely non functional, however I'm putting together a lower bolt on addition that I'll mount up when heading to the track.
- Removed factory fans and shroud and installed a single 16" spal
- Sealed up the front end as much as possible so that all air is forced through the rad.
- Toying with the idea of ditching the factory A/C since I use it maybe once a year.
- Ceramic coated headers.




I completely understand that if I decide to dedicate my car as a track car then the first thing to go is the FI setup, but for now I really love the way the powerplant is put together.

Thanks for all the posts, I appreciate the feedback!

Solofast

I thought about the subframe, but really, the front beam is basically the shear tie that keeps the front of the chassis twisting. The subframe is a big part, but the front frame is like the fourth side of the box and that's what closes the system.