[marks73ta]

Hey Keith. Crawled out, uhh, nooo! Kicked out, uh, yeah. Wife says I have to earn my stay now that it's cooler, heh. Getting back to yard, house and car projects. Had planned to have all of the suspension stuff done and roll it out for the BOP show that Steve has this November. But I've gotten fat and lazy in my old age. Mark L

[mechanickeith]

Ya got less than 2 weeks!!! Better get on it!! Saturday the 12th at Speedworld!!

[marks73ta]

I know. Been thinking about it but just floatin'. Not getting at it. Mark L

[marks73ta]

Hey guys have not been very active but I've got a seemingly small start on working on it again. Been redoing the yard, digging up all of the gravel yard that we built and preparing it for artificial grass. We graveled the yard first and then made the mistake of getting a dog. She knocks all the gravel into the pool so we are running artificial grass around it now. Anyway. I had four of the 3/4 inch heim joints for the rear of the bars and the steel tubing to build my ladder bars. I finally ordered and received the weld bungs for the ends. And I ordered spherical rod joints for the front of the bars. I'll take pics of them as soon as I have all the parts together. So I'm going to building the bars soon. I'm going to make a girder style but somewhere in the middle of the bar I'm going to add a flat steel plate support with a Pontiac V cut in it. Just for looks. They are going to be about 48 inch bars. Will know once I get started and do all the measuring.
Since I traded the single turbo for the twins, I've been building all kinds of induction systems in my head, and checking on prices, looking for deals etc. The engine will be capable of alot of HP, the twins will be capableof 2000 hp, but the single 750 will be the first restriction, followed by the intake and then the heads. So I've come up with possibly adding a Tunnel Ram with twin 750 blow thrus. I'v talked to the guys that built my 750 and they can duplicate it and also mod both carbs to work better as twins. Of course it just takes money. So I've been trying to sell a couple of things I've had sitting around to build money for that. With that system I will never be restricted before the heads. May never use the full potential of the intake system but it will never slow me down either. I also think the visual impact of the twin turbos, feeding twin intercoolers, feeding twin 750's, on a Tunnel ram will be just amazing. Let's just see if I can make it happen.
I also found a great deal on a 35 spline detroit locker and sent for it. I already have a 31 spline locker but I have always felt that the 31 might not be strong enough for the power and the heavy car. I just feel much more secure with 35 splined axles than the 31. If they never break I'll never know. If the 31 did then I would always kick myself.
So all that and when I find a good aftermarket speedometer I can start designing and building my final dash configuration. I did cut up and place my original dash in place but I'm still not sure I want that back in the car. It's a lot of weight for nothing. It was not going to do anything other than sit there for looks. I still want to the use the upper padded dash extension and make it bigger to reach farther back than stock. Maybe I can design and build a complete dash off of that. l think it will be better in the long run. So that is where I am right now. We'll see how it progresses. Mark L

[73 TRANSAM]

Mark,
Why not run a Dominator on it and let CSU build it for you. They are capable of 2000+ hp according to Kevin. Instead of a tunnel ram, just my opinion.

[BruceWilkie]

Mark, it would probably work well with a modified dual quad offy. Taff2 did a nice job of losing the "dip" at the runner entry on his hi rise version.(he's going dual quad blow-thru) Done right an A/W intercooler core (or AC evaporator)in a custom made hat could aid air distribution plus function well.(If A/W core too small for hp level an A/A intercooler sized appropriately between turbo's and smaller A/W core could work more effectively than just A/A alone, provided the A/W not too restrictive)
The A/W core would help unswirl the air and make it turbulent going into the carbs. (I'll sketch up someting for you and email you.)

Making your own intake isnt out of the question(Pontiac easier than a Chevy) if you have some fab skills. Low cost if using thin steel and plate, a tid heavy though, but probably similar to stock cast iron intake weight. ( Could mig or braze) Dare to be different... How about four 2-Jet carbs or Holley 4412 two barrels?

Dual quad gives you 4 needles/seats aiding fuel demands.

Dual 660 center squirt carbs with twin turbo intrigues me. (As does my pair of large primary thermoquads with solid floats)

Lots of possibilities Mark.

[marks73ta]

Just what you expressed Bruce. Twin carbs gives flow, gives two more float bowls, adds a lot more VISUAL IMPACT (not that I worry about in your face stuff, HA!!) and gives me the ability to run the single 750 CSU and a victor first to get it all running and the rest of the car dialed in, then drop in the second carb and tunnel ram. If the rest of the start up and build problems are solved, or at least identified, then, once all the intake is in place I can concentrate on that. Actually I have some 1/8 inch and 1/4 sheet aluminum some, and I have a spool of aluminum welding wire I was going to try to use my little welder to well it up and see if I could actually make it?? If I can get a good bead and seal on my welds I've thought of building an intake. THOUGHT about it, but not sure I'd ever do it. Who knows. Mark L

[BruceWilkie]

Taff2 has some pics somewhere showing his modded Offy. Looks good(like it was cast that way) With an intercooler as part of your hat its going to get some height to it. The visual impact is all in how you lay it out.

I've had success with silver solder and sheet metal. (Customized air cleaner base utilizing mopar air horn portion to fit my TQ to a 14" drop base held up just fine.) Im tempted to see if I can get success with silver soldering sheet-metal to 1/2" mild steel plate. If not, brazing rod and torch does well. (I cant make a mig weld look as good as those and not buying a Tig unless I hit the lottory.) If I make an intake that way it wont be as light as aluminum but I think it would be a tid lighter than a stock intake. Probably want a t-ram carb plate on top for ease of fabrication.
Or... go EFI and get creative.
BTW if you mig aluminum watch out the fumes dont get to you.

[marks73ta]

I saw his intake and at first I thought it was a custom Offy made sometime in the past, until he described the mods. It looked great for an Offy. I like the look of Tunnel Rams, and I want to build the intake system so the heads are the restriction. That way I can run to the heads to their limits and later I can have the heads ported if need be. I just don't want the intake to be the limiter. I have one air to water from off of the TA when I changed that to an air to air. I'll just match it with another one and run one off each turbo, then merge after them if I run a single carb. If I'm lucky enough to make my idea come true with the twin 750s and a tunnel ram I'll run the twin turbos thru the twin intercoolers and build a single carb bonnet feed with a dual feed from the intercoolers. Lots of ideas, just have to make it happen. This is the one intercooler I still have:



Mark L

[BruceWilkie]

AC evaporator cores wont leak water... the plenums are where you can get visually creative and also serve as part of your carb hats. The cores can also serve to help keep air turbulent and not swirl. Swirl can be the enemy of a hat design causing uneven pressures across the carb entrance.

Your heads are well sized for your cid. I'd only look for exhaust improvements. 320cfm on the intake is plenty for a 406. (MartyP was 270ish iirc) 320 is enough to support power to @ 7900 NA(@100%ve). At say 6500 rpm thats enough capacity to support @121%VE though unlikely to acheive. (If ex could support the intake it would allow fill 21% above cylinder capacity before boost was seen. However exhaust restriction from the valve and out would basically cause a "backup" in the cylinder before ex valve closed and boost will be seen sooner though much more cylinder fill boosted than a more restrictive intake side at same pressure.) In theory a 406 only needs @263 cfm intake port for 100% VE at 6500 NA. A bunch more factors involved to get 100% ve NA. However pressure reduction from improved Port flow capacity does reduce boosted charge temp and allow greater density per psi much the same way as an intercooler does.
Keep in mind with your turbo's, a good intercooler, and race gas you could make more power than MartyP. Will your motor hold up to that? Can you use it? I find myself asking those questions of myself. Impressive dyno/track numbers vs practicality. I think I've settled on pump gas and exceed 3 hp per ci and car flexible enough to drive anywhere, race it, and drive home, as my goal.

[taff2]

Pics of my modded Offy. I had intended using 450 D/P Holleys,but after reading about a guy over on Turboforums who successfully used twin 600 D/P Holleys I've gone that way.He didn't make any major mods to the carbs -blocked secondary HSAB'S,reduced primary HSAB'S,short vent extensions etc,the usual diy mods,and made around 1200 HP on a 427 Chebby. And the 600's are easier to find too.

[marks73ta]

Taff I love your set up. That is a killer looking Offy. I'm a big believer of a lot of plenum, hence I want to run a T Ram with the large plenum and the longer straight ports for some street torque off of idle and low rpm. I feel that my shorter (3.75) stroke will want longer runners for torque down low, and let the boost do the top end. Matter of fact. If the prices on Chrysler cross rams were not out the roof I'd love to adapt one of them. Even more so that the early cross ram M/T manifolds, the long port runners would give great street manners. Although I have to take a moment and think about the affect those long runners will have on all that boost pressure, if there would be a lot of drag etc and how it would all work together. Does any one think that long runners with boost pressures acting against the walls, do you think it could actually press the fuel out of suspension? If I were to go EFI then the long runners, I feel, would not be a factor??? Food for thought. Mark L

[BruceWilkie]

No need for long runner Mark.(IMO) The turbo will make plenty of torque. Plenum is good but too much can dampen low speed light load response.

Dont think the sonic tuning of a Mopar crossram will be noticed with boost. The M/T cross ram and the Old Edelbrock street tunnel/cross ram (Mopar "Rat Roaster") can be made to work well in their intended applications but take some re-work(air dams in the Edelbrock) to get fuel distribution in order. My brothers 426 wedge worked best with in-line dual quad top over the cross quad arrangement.(same carbs and manifold base). Car went quicker with stock max wedge cross ram(short runner version). Friend has been running a 413 long ram since high school in a street rod(yikes 40+ years). Looks neat. Torquey but balky cold starts and long warm ups even in warm weather.

Agree Taff has a nice setup. Dont know what the inside of the air box looks like but even though opposed entrance should distribute well the air could still be swirled some. Think I would add screen (like outer mesh of std air filters) in front of each outlet inside the hat to insure turbulence. I'd prefer two opposing inlets per carb and do so by going into a tee(helps reduce swirl) then 90 degree exits into air box giving opposed entry over the carbs and still the coarse screen. That should give max dispersion. The tee's and 90's being same id as turbo outlets will minimize restriction and sort of be a "plenum" before the main plenum. If it looks awkward you can create a cover over the plumbing and box and give the appearance of a bigger box. Aluminum or stainless sheet metal polishes up nice. Like I said I plan to put an intercooler inside my air box and I've just described how I plan to get max dispersion across the top of the core. As always subject to change.
Sounds like a tortured air path but corvair turbo was more turns and twists plus DRAW-THRU carb setup, yet gave good distribution.

The kicker?... Taffs setup may work just fine as is!

[marks73ta]

My dreaming on long runners was more to address the heavy car, short stroke motor, and the longer runner length for all off boost operation. I will be doing alot of stop light to stop light driving and I feel anything I can do to help off idle and low rpm torque is worth thinking about and of course letting the turbo do all the boosting power. Again just a mind excersize. If I had gone to a long stroke combination I probably would not even be thinking about it. The thing I'm not sure about (just don't understand all the physics fully yet) is the cam number versus runner length for torque. The tight 116 LCL will probably affect the runner length as will the later opening exhaust valve versus chamber filling due and how that affects the port flow at intake openning---etc etc etc--phewww. All my experience is around the N/A type cam timing etc. versus runner length etc. It may all go out the window with the drastcally different turbo specific caming numbers??? And now I see that some of the really big guns are starting to run turbo cams more near the N/A big cams as far as wider CL etc. Although the true big time power turbo combinations are after ultimate HP and do not worry aobut street manners etc, which is true to any motor combination built for full race work.
I'm wondering if anyone has any experience with the older cam combinations that the blower guys used to run back in the day. I'm guessing not far off from N/A cam timing??? Mark L

[taff2]

Thanks for the compliments guys. Mark,as far as cams go I would give your specs to a couple of different cam companies and see what they come up with. The cam that Bullet spec'd for me(and which was along the lines of what I was expecting) was much bigger than the cam I ended up with from Comp,both were solid flat tappet,both were reverse split cams. Comp were concerned that I would have trouble footbrake spooling the turbos with the duration of the Bullet cam. I think the big guns going to cams similar to n/a cams is because technology has improved to the point that big turbine housings (with the corresponding low backpressure that n/a cams like) can now be spooled easily.
Bruce, the inside of the box is 'square' to help break up any swirling ,but I've also incorporated a pair of K&N stubstacks to help direct the airflow into the carbs and to stop the airflow swirling around the air bleeds(even though the airbleeds will be blocked!). I am hoping it works as it is ,but can allways modify it, along the lines of what you said, using screens, if the plugs show any signs of poor distribution. Tom V suggested marine flashback screens which I take is a similar thing. I built an airbox many years ago with a large heater core inside the top of it,as a water/air intercooler, it seemed to work ok but one large spit back through the carb blew it up like a balloon!
I then switched to a draw through setup,I actually felt this drove better than the blow through setup,but at the time I wasn't as clued up on carb mods needed for blow through and there wasn't the info out there that there now is.

[BruceWilkie]

Personally wouldnt run an underlap cam unless my back pressure was significantly greater than boost at max conditions. Certainly not zero or negative overlap window . (A small cam could have underlap at .050 yet still have adequate overlap window).

If boost is greater than backpressure an NA style cam with somewhat reduced overlap will be fine and the engine will tend to follow the NA character of the cam.
At 1:1 ratio of boost/backpressure is pretty much same as atmosphere at the inlet and outlet of the engine. Zero to positive delta is a good thing! Understand that then you understand the "secret secret" of camming a turbo motor. Excess back pressure upsets the pressure balance the motor wants.

Pontiacs generally prefer longer exhaust event than intake. Single pattern would be as close as I'd care to go, not reverse split.

POST 2 for more insight... http://forums.maxperformanceinc.com/...d.php?t=683159

[taff2]

And there lies the problem Bruce, you need to run the engine and datalog the T.I.P first to be able to pick a suitable cam,however,what cam do you start with in the first place? Because different cams will change the amount of power you make,how much exhaust gases you produce,and ultimately how much backpressure you will see. This is where experience of camming turbo combos and sizing of turbine housings/wheels comes into play.. My Comp reverse split turbo grind has 4 degrees more intake duration than exhaust @.050" (249I/245E) but still has 18 degrees of overlap @the .050" numbers, I can datalog this setup with my LM1 and if need be change to another cam(hopefully I won't have to!)

[Engine-Ear]

...geez, you emmer effers are blowing my mind. Mark, WHEN I visit, I expect a serious ride in that DarkSider.

[quick67bird]

Car is coming along nicely. Can't wait to see the finished piece.

[marks73ta]

Matt, taking a ride down today to Classic Cars to give them your info. I'll give ya a ride anytime, if I ever get it at least on the road. The pretty stuff can come in later. Lots to do though. Thank you all for the nice comments and encouragement. It all means a lot me. I got my spherical rod ends yesterday so I will be adding some pics today of where the ladder bars are. Any pics you guy have of big long laddr bar constuction would be appreciated. I'm still in the planning stage as to construction. The only thing set is the length. They will be 48 inches, rod end to rod end. I have to get under the car to see where the ride height of the rear axle sets the top bar as the straight run and the bottom bar comes up to meet it, or if the bottom will be the straight bar and the top comes down to meet it? Any thoughts on tne dynamics/physics of the bars in either configuration is appreciated. Top bar straight, bottom bar pushes up on rod end. Bottom bar straight, top bar pulls up on rod end. What might be the implications of either design? The ladder bar front rod ends will be the sole connection and take all of the weight and force of the rear end to frame connection. So it is a rather seriously important area. Thespherical rod ends are 3/4 rod and bolts so it will take a lot of stress. Lots of physics going in there.
I already have the cam. I is designed by Harold, he was the designer for the Ultradyne cams and several others. I don't have the spec card here but it is 251 intake/241 exhaust on a 116CL, 4/7 swap solid roller, around net .650 lift for both. Mark L