Ground Clearance Question

[npez]

In looking more at the twin-turbo setup in the nose of my TT 300ZX w/VH45 swap, I'm thinking more and more that some of the exhaust plumbing will need to go under the crossmember. There is simply not enough room to do so otherwise and keep the accessories (p/s & a/c).

So, from what I've read the TT Z came stock with 5.1 inches of ground clearance. Subtract the .8 inch drop from my Eibach pro springs and that leaves me with 4.3 inches today. Let's now go on a brief tangent.

On the supercharged/twin-turbo compound boost turbonetics Mustang Cobra they ran 3 inch pipe underneath their crossmember. I'm assuming here that their crossmember is probably close to the lowest point on the car as well. This mustang came stock with 4.5 inches of ground clearance. In the article I read they said there is "no ground clearance issues" with that setup. I also noticed however that there is no room for the air filters on the turbos - so I take that statement with a grain of salt.

So back to the Z. As I think there *is* a ground clearance issue with my car, I was thinking of having custom tubes made by a company called spintech. I spoke with them today and they told me they can make me oval tubing with a frame clearance section that will allow the pipe to go up a bit at the crossmember/steering rack area while flowing the same as the round tube. The idea is that they go up a size or two on the oval tubing to provide the flow.

The standard oval tube offering is 1.75 inches tall - so doing some math that would leave me with about 2.5 inches of ground clearance. If they do the frame clearancing for the crossmember, I can probably get another inch of ground clearance for a total of 3.5.

Now for the thousand dollar question: is the extra inch significant enough to merit the extra expense (read: about $250+/- per pipe x2 pipes minimum possibly 4 pipes maximum)?

I'd love to hear your thoughts - especially if you have a lowered car.

Thanks,Nick.

[npez]

Ferrari F50: 3.9 inchesLamborghini Murciellago & Gallardo: 5 inches Murciellago at speed is less than 1 inchFord GT: 5 inchesSaleen 550: 4 inches

Looks like for some reason 4-5 inches is the magic #.

Doesn't look too good....

Nick.

[T45]

Oval tube is a great idea. If it were me (ie: make it yourself, save money, benefit of being able to say you did it, typically less asthetically pleasing as professional products) I would take your 3 in tube and flatten it. Basically that's all they are going to do for you anyways, minus the scratch marks from doing it yourself.

You can start with a big vise and some tube. Protect the tube with wood or rubber and vice it slowly along the tube, back and forth until you get your desired length and oval.

Get a heavy vehicle and jack it up, place tube under tire and lower it until you get desired effect. Again protecting tube from asphalt with wood planks or some sort of wrap around tube.

That's what I would start with. Then you have 250x4 to spend on other things like stuff for your wife. You owe her CUZ!!!

"Diamonds. That'll shut her up."

[Q45tech]

Since most shocks have a +- 3.5" stroke and tires can compress an additional 1" hopefully you see why 4.5" is the minimum.On a perfectly smooth track [< 1/2" bumps anywhere] you might be able to get away with less.

[npez]

Oval tube is a great idea. If it were me (ie: make it yourself, save money, benefit of being able to say you did it, typically less asthetically pleasing as professional products) I would take your 3 in tube and flatten it. Basically that's all they are going to do for you anyways, minus the scratch marks from doing it yourself.

You can start with a big vise and some tube. Protect the tube with wood or rubber and vice it slowly along the tube, back and forth until you get your desired length and oval.

Get a heavy vehicle and jack it up, place tube under tire and lower it until you get desired effect. Again protecting tube from asphalt with wood planks or some sort of wrap around tube.

That's what I would start with. Then you have 250x4 to spend on other things like stuff for your wife. You owe her CUZ!!!

"Diamonds. That'll shut her up."

Ben,

You may have something there. I was under the impression they did something special for this process. My neighbor has a shop that services BMW/Mercedes, and I believe he has a 20-30 Ton press. I can ask him if I can borrow it and like you said use a 2X4 for the 12-18 inches that I need flattened further and press it down another inch.

I definitely owe the wife..... I'll will have to see what I can pickup for her

Thanks again,Nick.

[npez]

Since most shocks have a +- 3.5" stroke and tires can compress an additional 1" hopefully you see why 4.5" is the minimum.On a perfectly smooth track [< 1/2" bumps anywhere] you might be able to get away with less.

I see what you're saying. So can I conclude from this that even at 3.5" may still be a major issue? This isn't a daily driven car, but I don't want to be scraping everything when I do take it out. Another option is to go coilover, set to stock ride height and get to 4.3" ground clearance. I'm just trying to determine from all the options what a reasonable compromise in ground clearance may be.

Please advise.

Thanks,Nick.

[npez]

The GT3 has 3.7 inches of ground clearance - I read that everyone is scraping, but I'm optimistic that if I can get the Z to this level, it may be acceptable enough.....

Nick.

[SuperHatch]

Nick,

You mean like this? http://www.airpowersystems.com...g.htm

APS ducts their turbo charge pipes under the front crossmember using flattened tube. There are pictures in that link.

Good luck!

[npez]

Nick,

You mean like this? http://www.airpowersystems.com...g.htm

APS ducts their turbo charge pipes under the front crossmember using flattened tube. There are pictures in that link.

Good luck!

Exactly correct. The flat section should give me about an inch more clearance than running just oval tubes. If you notice in APS' pictures they go from round to flat - on mine it would go from oval to flat giving me even more space and smother transition.

I spoke with the exhaust guy and he said once he looks at it he'll make it all work properly. So we're shooting for next Friday having the car flatbedded over and I'll stay there and help on Friday/Saturday. By then, I have to have the oilpan in (which unfortunately hasn't arrived yet), the A/C back in, the P/S clocked and mounted, the Howe radiator and factory condenser installed, aux and main fans installed, the turbos mounted, and the mid-pipes (testpipes for now until I get the motor running properly) back in.

I'm expecting the 2 K&N filters, remaining flanges, fan controller, and MAF by Tuesday/Wednesday so I should have most of the materials ready. I hope this will give him the most accurate representation of constraints.

Once the manifolds are done, I think it'll be downhill from there. A lot of work, but I think it'll be worth it in the end.

Thanks,Nick.

[qsiguy]

Well, totally different car but I'll give my $.02.. First try at going under the engine with my compressor tube was pretty bad. It was about the last piece before I could get it on the road, it was on the jacks and I didn't put much thought into it. It would hit all the time while on stock suspension, of course my shocks were junk so it was not as stiff as it should have been.

Now with my latest mods, I redid the plumbing from under the driver forward and hugged the bottom of the engine/cross member and replaced all the front compressor tubing because I added the intercooler. I wanted to do oval tubing under the cross member but I was having trouble finding someone to do it and I wasn't having much luck doing it myself but honestly I didn't try very hard. I had some 4" C-Channel steel put the pipe under and drove over it in the truck. Didn't even budge. It might have worked had I cut the length down a bit or use a heavier vehicle. I shop press would work, I would get some 4-5" c channel to press it in, that way it will be even across the length.

New install has not scrapped once. I am even on lowering springs now but it is much stiffer. My clearance at the lowest spot under the cross member is only 2.75". Of course I am careful going in driveways. With the first tube I couldn't even back straight out my driveway or it would hit, now I can. Ended up just using the round 2.5" round tube. Oval tube would have got me another 1" or so which would be nice. I suggest the DIY method with a shop press. I'm sure I will eventually hit something.

Here's the new one.

[npez]

Well, totally different car but I'll give my $.02.. First try at going under the engine with my compressor tube was pretty bad. It was about the last piece before I could get it on the road, it was on the jacks and I didn't put much thought into it. It would hit all the time while on stock suspension, of course my shocks were junk so it was not as stiff as it should have been.

Now with my latest mods, I redid the plumbing from under the driver forward and hugged the bottom of the engine/cross member and replaced all the front compressor tubing because I added the intercooler. I wanted to do oval tubing under the cross member but I was having trouble finding someone to do it and I wasn't having much luck doing it myself but honestly I didn't try very hard. I had some 4" C-Channel steel put the pipe under and drove over it in the truck. Didn't even budge. It might have worked had I cut the length down a bit or use a heavier vehicle. I shop press would work, I would get some 4-5" c channel to press it in, that way it will be even across the length.

New install has not scrapped once. I am even on lowering springs now but it is much stiffer. My clearance at the lowest spot under the cross member is only 2.75". Of course I am careful going in driveways. With the first tube I couldn't even back straight out my driveway or it would hit, now I can. Ended up just using the round 2.5" round tube. Oval tube would have got me another 1" or so which would be nice. I suggest the DIY method with a shop press. I'm sure I will eventually hit something.

Shane,

Thanks for the feedback - that's good to know - especially on the ground clearance. I think the DIY is what we'll do unless Rodger (the exhaust guy) finds an even better way to do it. I'll let you know after he takes a look at it. I can't wait - I'm getting impatient now....

Thanks,Nick.

[tmorgan4]

Nick,

Did you go about researching prices on oval exhaust tubing online? It really isn't that much more expensive that normal, round tubing if you look in the right place.

I can't tell exactly what you're needing (how much oval tubing are you going to run?) like the APS system with a 12" long oval section or all the way to the back of the car?

Here's the first site I found. Looks like 36" of 3" oval tubing will run $65. http://www.drgas.com/developme...tid=3

Here's another that actually tells you the material of the tubing. http://www.boyceindustries.com....html

Are you going to run aluminized steel or full stainless?

EDIT: Looks like the second link requires at least 300ft of tubing to be purchased. I guess those prices won't be a good representation of what we'll pay for a few feet.

[npez]

Nick,

Did you go about researching prices on oval exhaust tubing online? It really isn't that much more expensive that normal, round tubing if you look in the right place.

I can't tell exactly what you're needing (how much oval tubing are you going to run?) like the APS system with a 12" long oval section or all the way to the back of the car?

Here's the first site I found. Looks like 36" of 3" oval tubing will run $65.

Here's another that actually tells you the material of the tubing. http://www.boyceindustries.com....html

Are you going to run aluminized steel or full stainless?

EDIT: Looks like the second link requires at least 300ft of tubing to be purchased. I guess those prices won't be a good representation of what we'll pay for a few feet.

I looked at spintech as well as some other places. I'm going to be running full 304 stainless for anything exhaust related. My B&B cat back as well as my random technology cats are stainless steel as well. So in that spririt I'm keeping everything else stainless as well.

Yeah the oval tubing isn't too bad as far as cost what got expensive was having spintech make a custom pipe with frame clearancing as transitions back to round on the end. Rodger at the exhaust place said all that isn't too difficult to do though. So I'll see what he has to say when I see him next week.

I'm planning on oval just for clearance purposes from the cats back it's all round stainless.

Thanks,Nick.

[craigztoyz]

Since most shocks have a +- 3.5" stroke and tires can compress an additional 1" hopefully you see why 4.5" is the minimum.On a perfectly smooth track [< 1/2" bumps anywhere] you might be able to get away with less.

This is the last RX7 I did, ran a built Small Block Chevy, 700R4 AOD, with 4.10's, posi...... Fun car. I ran Dual 2 1/2 " pipe throughout. High-Flow cats, Magnaflow Mufflers, 5" tips, equalizer pipe.. with the race springs, and konis, it had ruffly 2- 2 1/2 " for a 3 foot area behind front wheels, a lil more throughout the rest of car. Thought it would skip and kit on everything.

Drove the piss out of it, 2 engines and 2 trannys in 1 year. Hit it a few times at local supermarket bumps, and a few times at over a bill, when you hit a incline, or a dip on freeway.

So in my opinion if you oval it you are ok, for where it is, only a 1 foot section under the x member. Pretty safe. I still say to flatten it yourself, but if you are going stainless, then well that would be a lot more difficult.

That is way to much to pay for what you are getting. You could use your torch and try to do it

[qsiguy]

Use the press with and sandwich it in some C channel and if it's tough going, heat it with a torch. No sweat!

[npez]

Thanks everybody for your feedback. Rodger thought $200+ was too expensive as well. Once we look at it on Friday we'll see what needs to be done. He mentioned that when you press tubing like that, at times it completely collapses, but he said worse case scenario he can section the pipe and TIG weld the flat clearancing portion on there.

We'll see what he comes up with and what it'll cost but I think it will be way less than $400+. I'll be happy if the total job comes out to $600+/-.

For research purposes I also requested a quote from high performance coatings to get all this and the turbine housings coated with HiperCoat Extreme. This stuff has been independently tested to knock about 900*F off the surface temperature of what's coated and is stable to 2000*F. IRL and Nascar use it and is FAA certified as well, so I've got a feeling I'm going to experience sticker shock.

Thanks,Nick.

[qsiguy]

...He mentioned that when you press tubing like that, at times it completely collapses...

That's why I suggested putting it in some C channel. It will limit how far you can collapse the tube.

[tmorgan4]

That's a very good idea. Get some C channel where the channel is the same height as you want your tube. It would help keep every piece of tubing the same oval shape and probably keep a lot of the marks from the press away from the tube.

[npez]

That's why I suggested putting it in some C channel. It will limit how far you can collapse the tube.

ah ok - missed that part Thanks Shane.

Nick.

[craigztoyz]

You could also cut the pipe and lay in flat pieces to gain extra space for that 10" area you have space issues at . I sthink it is still called 'sectioning' the pipe.

A pain in the butt, and if not done right will f up air flow. , by right i mean oval it as much as you can, and then section out a bit more. But you dont want any real restriction.

[SuperHatch]

Why not take a piece of 1.5" - 2" pipe, split it down the middle, then add in some flat pieces top and bottom to make it oval? Then take your 3" pipe, cut a wedge in it, then slide it over the oval and cut out the transition and weld it in. Easy flat pipe with a smooth transition.

[craigztoyz]

So many ways to make a taco. Only the eater knows which is best.

I like your idea too, have not seen it done in a long time, and it wasn't used for exhaust but for water flow on a sandrail with a real engine.

It is doable too, but I'd oval my own first, and use a 1 1/2" pipe through it and then press it, and hammer and dolly the F out of it till it meet my needs.