Time to go Stage II!

[Alky V6]

Another thing to consider. When these cars get up to some good mph numbers, the hood wants to push downward. I'm sure some have seen the pictures of cars on the top end that were using very lightweight fiberglass hoods, and the hood was collapsed down immensely.
I had seen a little of that tendency with the old motor where the hood pushed down against the throttle body and left contact marks on the throttle body mounting flange and the underneath of the hood. I'm thinking that if I put the throttle body and up-pipe back up through that hole, I can build some small, discreet pads that will help support the hood when it tries to collapse downward when the car is up at speed.

 

[geno]

I had to put some teflon rub pads on the underside of my hood

 

[Alky V6]

This is the dilemma I have with the exhaust header stub for the number 5 exhaust port. I'm tapering the ID of that runner, starting in the adapter and continuing out through the flange and into about an inch of the stub of the header tube. I need to start the turn on that runner at the start of the flange. That shouldn't be much of a problem hand forming a taper and radius turn through the flange, but then continuing the taper and turn through the short section of stub tubing might be an interesting challenge.
Tapered, mandrel bent tubing.

 

[Mike E]

That doesn't look like much fun. What's the CLR on those sewer pipe sized primaries? Here are a couple shots of some 1 3/4 on a 2.5" CLR tubes for reference. Don't know if your going to go over or under the steering shaft, so here are pics of both. Obviously there are no adapters here either. 1/2" thick flanges and I started the bend inside the flange, but didn't cheat the bend.

 

[Alky V6]

The tightest CLR they have listed for the size tubing I'm using is 2.35.
Yes, that will be the trick. Not to cheat the bend.

 

[Alky V6]

LOL Sewer pipe sized primaries.

 

[Alky V6]

All the runners actually have a 7 degree upward angle start through the adapters, so the adapter is helping out on this a little.

 

[dereklola]

I'd just put more UJs in the steering shaft - looks like you can easily move it up and left out of the way of the 'go down' headers. You'd need an extra shaft mount on the suspension structural frame but looks doable. We do it all the time on my sort of cars (single seater open wheel). Derek

 

[Alky V6]

Thanks, Derek. I'm pretty confident that I'll be able to make the turn without having to move the steering.
I was frustrated that Danica didn't win the Daytona 500, so I went into the shop to work on the intake plenum.
There she is,... sitting there whispering to me, "Take me to the track. Please."

 

[Alky V6]

I made some rough cuts for the runner openings through the lower plenum housing.
You machinists out there, check out my cutting fluid acid brush. I'm sure some of you might recognize the special bodywork.

 

[Dusty Bradford]

Another thing to consider. When these cars get up to some good mph numbers, the hood wants to push downward. I'm sure some have seen the pictures of cars on the top end that were using very lightweight fiberglass hoods, and the hood was collapsed down immensely.
I had seen a little of that tendency with the old motor where the hood pushed down against the throttle body and left contact marks on the throttle body mounting flange and the underneath of the hood. I'm thinking that if I put the throttle body and up-pipe back up through that hole, I can build some small, discreet pads that will help support the hood when it tries to collapse downward when the car is up at speed.

I can't explain the dip in some hoods but if this were true, you wouldn't need a hood latch or hood pins. Make a pass without the hood latched down and see what happens.

I have driven a Regal with a cowl hood and the hood clearly rises at the base of the windshield. If it ran over 140mph in the 1/8 the hood was easily 1-2 inches higher at the base of the windshield.

 

[Alky V6]

I can't explain the dip in some hoods but if this were true, you wouldn't need a hood latch or hood pins. Make a pass without the hood latched down and see what happens.

I have driven a Regal with a cowl hood and the hood clearly rises at the base of the windshield. If it ran over 140mph in the 1/8 the hood was easily 1-2 inches higher at the base of the windshield.

Is the grill area blocked off on that Regal to control air entering the engine bay?
If you go back to one of the latest pictures I posted that shows the front grill of my car (page 104, post #2070), you will see that the grill area is blocked off, except for a small series of holes to let cold air get to the air filter.

 

[Alky V6]

A note on those lift plates I made up for removing/installing the engine. They worked great. They deflected very little. The lift bar is on the short side, so I was worried that the angled chains might cause the lift plates to deflect, especially the rear one bending into the valve cover. They did deflect a little, but not enough to cause any issues. With the engine fully supported with the turbo and some of the front accessories also mounted, the clearance between the rear lift plate and the valve cover was still enough to run a double folded rag between them.
The weight was not perfectly balanced, though. With the added weight of that huge turbo suspended so far out in front of the engine, it wanted to dip slightly in the front. Not so much that it was unmanageable, but it was not perfectly level. I think if I added one more bolt hole option to the inboard of the front lift plate, that would take care of it.
If the turbo weren't mounted to the engine, I'm sure the lift plates would have worked out fine, as is.

 

[Dusty Bradford]

Is the grill area blocked off on that Regal to control air entering the engine bay?
If you go back to one of the latest pictures I posted that shows the front grill of my car (page 104, post #2070), you will see that the grill area is blocked off, except for a small series of holes to let cold air get to the air filter.

Yes. Blocked off with Lexan.

 

[Alky V6]

Yes. Blocked off with Lexan.

Interesting. I'm at a loss to explain it then, too.
What is the attitude of the car? Car lowered? Level? High in the back? Taller spoiler in the front? Fenderwells still in place?

 

[Squid4life]

Very interesting... May have to dig out some old drag racing DVD's. I have some of the "King of the Hill"/ Fastest Drag Radial type racing, so I will have to compare the hood action to the car setup. I seem to remember some hoods lifting, some being pulled right off, and on Pinks in-car some going both up and down. Will have to pay more attention to it...

Interesting topic, and the items you mention Donnie make perfect sense. My GN has no inner fenderwells, and even no front spoiler. I would imagine an upward pressure in that instance, but since the thing has never been running in my posession, that is only an assumption. The amount of rake I imagine would play a pretty large part in it as well. Cool info here.

 

[Dusty Bradford]

Car was lowered. No chin spoiler or fenderwells. Just about every race I see a hood blown off of a Mustang and they are all blocked off with very low chin spoilers and fenderwells.

 

[Squid4life]

Dusty, do you think the hood lift-off event could have been caused by no air under the nose of the car, (making it more "neutral") and a ton of pressure pulling the hood up near the cowl? I have seen/read a little about trying to equalize the pressure both at the cowl, and at the rear window/decklid area, but have forgotten most of it, or even where I read it...

 

[Dusty Bradford]

Dusty, do you think the hood lift-off event could have been caused by no air under the nose of the car, (making it more "neutral") and a ton of pressure pulling the hood up near the cowl? I have seen/read a little about trying to equalize the pressure both at the cowl, and at the rear window/decklid area, but have forgotten most of it, or even where I read it...

I wish I knew more about the aero of these cars but I don't. I have seen video of hoods caved in as Don has mentioned but I see way more of them blowing off the car. This leads me to believe the hood is really trying to come off the car.

Geno has a solid glass front end and it appears his hood is being pulled down, but what's pulling it down. Is there a vacuum under the car at high speeds or is it really the force on the front end of the nose is forcing a downward bow in the hood???

 

[Squid4life]

Damn... Maybe we need Neal to do some aero testing since he is the only super fast Buick down here running right now, huh Donnie!?


Aero is something I never really considered until buying the race car; never been fast enough where it mattered. But now will be a different story...

Aero popped in my head the other day when I drove the 85 to work. It was outside overnight, and had a light layer of dew on the hood/top/trunk. When I got to work I looked at the trunk and you could plainly see where the air came over the roof then down onto the decklid. It hit the decklid right in the middle (middle front to back) in two little swirls. One swirl on each side of the lid, and you could really see how the air came over the roof, hit the deck lid, swirled back toward the rear glass. Very interesting. I know Neal and I had talked a little about this in the past but it was interesting to "see" it. Would be really cool to be able to take a GN into a wind tunnel and try different front and rear heights, front spoiler lengths/rakes, rear spoiler height/length/angle, etc. Not very practical, but would be awesome data to have on the board for future fast guys or just to share and confirm thoughts and assumptions.

Donnie, I nominate you. Time to build a wind tunnel/smoke machine in the shop!