Driving Impressions: Part Deaux

[Y-TRY]

This should give the rest of you turbo guys a thrill.....

If you don't know already, and to set the scene: I have a '68 Camaro, 6" rod, solid roller, AFR-headed twin-turbo, MoTown block 406 backed by a Tremec TKO. So far I've seen 720rwhp and 614pwtq at a measely 6psi, pump gas. I used to have 3.89's and now have 3.25's, and have tuned it to 9.7psi, still pump gas (no telling/proof what the power is now, but guessing in the 800rwhp zone)......

So I go out to stretch the car out on a country road out here... A few minutes into my drive I find myself behind an old pick-up going 60 in a 70mph zone. This just won't fly with me so I decide to pass. Boy do I love this gearing!! In 4th gear, I lean on the throttle some and decide to pass him. As I pass and get back into my lane, I slowly lean on the throttle more and more, reeling in the open stretch of road ahead of me. The truck is a distant memory in my rearview mirror by now. I continue to evenly lower the pedal. At just above 3/4 throttle I realize that the car is going sideways. Not sideways like you'd be used to at a redlight, like the rear is trying to pass the front. But rather, it starts to pivot on an axis that seems to be right in the middle of the car. It's nothing like I've felt before.

Immediately, I let off the throttle. I'm now lurching side-to-side trying to regain control. My life, and this entire build-up, flashes before my eyes as I'm sure the car is about to roll. I glance down to the speedo as I feel grip again...

...125...120...115...

I just blew the tires from about 70mph to about 130mph on the highway, with 3.25 gears!!! It was probably one of the scariest car-moments of my life. I could almost see my car shaking it's finger as if to say "tisk-tisk".

I think we're really tapping into some major power, that comes-on in a different way that even the baddest of us are not used to. I now have much more respect for the car, and the power curve of a twin-turbo'd small block. :hail:

This is an absoltue true story, and I have the soiled boxers to prove it. :yes:

[jonny51]

Damn, I could see where that would scare the crap out of you. :drive:

[Rick Dorion]

Nice description. I was there with you. I'm now totally dissatisfied with my new heads :(

[XcYZ]

Sounds bad ass. :thumbsup: Can't wait to drive mine.

[TwinSting]

What a great description of a great story. I was seeing it as if I was there.

Now I just can't wait to get mine out on the road so I can feel that for myself!

[Blown353]

Sounds fun. And scary. Breaking traction at high speed is very unnerving but entertaining at the same time, and that's what you have to watch for, the fun can turn dangerous quick! Seems like everytime I take my car out I find myself purposely spinning the tires from 60-80 just because it's so much fun; I don't even bother with spinning them from a standing start or anything slower than 50 or so because it's boring. :P

Since I finally got my injectors swapped, I can wind the thing out now-- I had something very similar to your incident happen yesterday afternoon, the car got loose at about 100 in 3rd gear. I put my foot in it, it hooked for a moment then it did little side squirm, so I countersteered and kept my foot in it because it felt like it hooked back up. Just when I thought everything was OK it squirmed again, then it went into side to side wag just as you experienced. I gathered it up, slowed down, and then I started thinking about what could have happened and that's when my hands started shaking a bit. Moral of the story: don't think. Had something happened though it would have just been between me and the walnut orchard, which would NOT have been pretty. Trees don't move much.

I had another high speed incident last year with my first hydroboost experience-- I twitched on the brake pedal slowing down from the top of 4th gear and locked up all four tires and pitched the car sideways... at just over 150 mph. By the time I gathered it back up the speedo was reading 110. I had to pull over, get out of the car and take a breather after that one. You should never, EVER be looking at a concrete K-rail at 150 straight out of the front windshield. :eek:

Remember, keep the shiny side up!

On a more technical note, have you ever tossed a TC into your manifold? I'm very interested what your discharge air temps are like at 10psi without an interooler.

Troy

[camcojb]

Nathan,

Be careful!!!!!!! :eek: I've had the high hp stuff and it can bite you if you get a bit overconfident. One suggestion that helped a lot on the last car I had; get some drag radials on it. Although it still won't dead hook it will take the "edge" off and make spirited driving much more predictable.

Jody

[Al Moreno]

You guy's have alot more guts than I do, That's some scaaaaaary ****!!! :hail:

[69rs]

I would hate for y'all to ball-up those bad rides.....but dang, that's awesome!!

[Steve Chryssos]

Not good.

Sooner or later one of our buddies will get hurt by this horsepower escalation. Actually, it's not the horsepower directly. The power propels these cars to speeds that generate LIFT!! I think it's time to find a book called Aerodynamics for Dummies. JP's II Much should be able to stick well given it's spoilers and channeled body.

[parsonsj]

Those are scary stories (but awesome!). Cars spinning tires at 80 mph! Amazing. :thumbsup:

I don't have the 800+ hp of some of these unnaturally aspirated beasts, but I've never driven a high hp car before so I'll be damned cautious at first. I definitely want to live a while longer.

I hope Steve is right and my car's stance, air dam, and rear wing will keep the car civil at high speed. But it's not as if I did any wind tunnel testing. Who knows? Maybe I need to make a bigger wing for the back.

jp

[Blown353]

The high-hp is a mixed blessing John. I'd love to experience it at slower speeds, but the fact of the matter is I can't hook up until about 80. That means for me to really feel the thing pull I have to do 80+ mph hits. That's not very safe or sane-- things happen fast at those speeds, and the consequences of an error are much higher. This holds true for just about everyone making big hp numbers and running it through street tires. You just don't have the traction to use the HP at a reasonable speed.

I find it's a lot easier to make stupid amounts of horsepower than to find the traction to use it all. I would love it if I could stand on it from a dig, or even 35-40 mph and have the sucker hook up and then shut it down at 80 or 90; I would have my "fix" at that point and get on the brakes and return to reasonable speeds. Right now with my traction issues I have to wait until 75-80 and then ease into it. I usually do my "fun runs" starting in 3rd at about 75-80 and then run it to the top of third (115mph). The problem is by that time I want more fun, so I upshift into 4th and keep going part way into or sometimes to the top of 4th, which is 155 mph. It gets there so fast I don't realize or think of how fast I'm going and what could happen until I'm slowing back down.

Why can't I push a button on the steering wheel and have super-duper traction tires like Speed Racer had on the Mach V? That would solve my problems. :P

My next tire change I want to try either drag radials or road-racing tires out back. Hopefully that will allow the car to hook at a lower speed and allow me to have the same amount of fun but end at a lower terminal velocity.

As Steve stated, lift is also a big concern. I know for a fact my car gets very light in the nose above 165 or so, light enough such that I dare not venture into that territory anymore. The simple fact is our cars were never intended to achieve these kinds of speeds, and something has to be done to help mitigate lift and aid stability at high speeds. John has a good start with his chin and rear lip spoilers, but real world or wind tunnel testing may prove them to be either beneficial or harmful. A gut hunch and some virtual-CFD diagrams in my head makes me think they will help. How much, I don't know. Let us know when you get it on the road John! :)

Troy

[parsonsj]

Troy, I appreciate the insight about what that kind of horsepower means. I'm still trying to wrap my mind around it.

Man, I'm dying to get my car on the road. I'm figuring on 600+ hp from a 427 LS2. Just normally aspirated ... no positive atmosphere or anything. My tires are Pirelli PZero Corsas. Like I said before, I really have no idea how it will behave at any speed. I'm thinking the fun is finding out. Can't wait!

jp

[Y-TRY]

It was definately a wake-up call. I think it was a combination of the tires getting loose and lift that caused it to pivot like it did.

It's a fun story to tell, but I want to avoid things like that in the future. Otherwise you'll have to read it on my headstone.

I even thought I was being pretty conservative. I hardly stabbed the throttle. But the power-curve from the turbos with the stretched-out gears really lets the power sneak up on you. It feels totally different to me than high-hp naturally aspirated and juiced cars.

The moral isn't for everyone to go try and see if they can do it, too. The moral is to be very careful.

[Steve Chryssos]

http://members.aol.com/ytry68/CamaroPics/New2

Was your banzai run made without a front spoiler? If so, please install one ASAP--be sure to get the brackets that go with it and re-test (with helmet on)

Post results here. Thanks.

[Y-TRY]

http://members.aol.com/ytry68/CamaroPics/New2

Was your banzai run made without a front spoiler? If so, please install one ASAP--be sure to get the brackets that go with it and re-test (with helmet on)

Post results here. Thanks.

Yeah, no spoiler at the time. I have a new spoiler and the brackets but I can't get them to line-up for some reason. Anyone have a diagram of how they should go on? It seems pretty simple but the side rods don't even come close to lining up with both the spoiler and valance holes. The center one won't work because I notched the valance to make room for the up-pipe.

Looks like I may have to fab one out of a solid material, but I'm sure it will last maybe a month before just being scraped off.

[Payton King]

You may have one for a 69. 67 and 68's are not as wide but look exactly the same.

[Y-TRY]

Thanks Payton, I'll look into that. I ordered it from Year One, but this one does seem to be a bit narrow. The braces don't reach from the holes in the fender extensions to the holes in the spoiler. I never knew that the '69 was narrower and that could be the problem.

:thumbsup:

[Blown353]

Am I the only one that thinks a nice fabbed brushed aluminum chin spoiler would look better on the front of that Camaro than a black plastic factory piece? ;)

I've been working on one for my car out of .125" or .188" thick 6061-T6 that will bolt to the bottom of the radiator support and the front frame horns. I just haven't made one that makes me happy yet. I whip up a flat pattern in CAD, use our NC cutting machine to cut one out of thinner stock for ease of use, then tape it on the car and stand back and look. So far I haven't got it quite right; I've been playing with various rakes and height tapers trying to settle on something I like.

When I decide on one, I should whip up a little model of the car and the chin spoiler and take a drive over to my alma mater, instrument the sucker and throw it in the little wind tunnel and get some data. I'd prefer it be effective rather than just cosmetic. I'm not a big fan of cosmetic-only mods...

I'd love to park my whole car in the giant wind tunnel at NASA's AMES facility (I have friends there) but I don't make enough in a year to pay for the electricity to fire that thing up for 5 seconds... it's rather expensive to power up 6 electric motors that make 22,500 horsepower... EACH. :P

[Steve Chryssos]

That's what we're here for. Let's have a looksie. Don't be shy now. Post a picture.

[Blown353]

That's what we're here for. Let's have a looksie. Don't be shy now. Post a picture.

I'll post pictures of the next trial piece, I'm planning to whip up another couple of variants hopefully next week.

I wouldn't mind doing an adjustable decklid lip spoiler like John has done, but the sloping and crowned trunkline of my car would make things look very akward; I'd have to scoot the hingepoint of the spoiler up to the first peak on the trunk, split the spoiler in the middle to account for the crown (no biggie) and have the turnbuckles anchored at the bottom most portion of the trunk lid. I don't want to run the turnbuckles down between the taillights, then I'd have to do quick disconnect linkage every time I wanted to open the trunk; unfortunately that would provide the turnbuckles with the straightest shot at the spoiler. Running the turnbuckles to the edge of the trunk lid would mean a rather severe angle on the turnbuckles and put them at a disadvantage for leverage on the spoiler itself. Another something to think about...

[parsonsj]

Yeah, my wing was fairly easy to do since my decklid is mostly flat. It does have a little crown which is why my wing is two pieces.

I'm thinking it might be a good idea to make a taller wing to aid more at high speed. The time to do it is now so I can get then both anodized the same color.

I'm with Steve: let's have a look.

jp

[Raige]

Gents Dont take this wrong but i know turbos and you very luck to be alive.
They make hp cheap but you have to set it up right... you have the hp now make it smooth... But you have to like the feeling of total hp at speed heheh congrats and welcome to a new curve :O)