Second Chance at a MOPAR the "BlackBird" build

[Blackbirdsrt78]

Its going to be mild..really mild unless I can find a forged crank block. I will be using cast pistons and the cast crank. I don't think it would stand up to boosting to 400-500 HP. 300 seems right to me it may not even get that high who knows until I try it. and I wont be the first either. all the parts accept the input flange are at the junk yard or ebay. 300 HP is nothing to sneeze at. hell I was considering the expensive v-6 swap to get the car there. there are piles of slants out there for cheap. parts are easy to come by for them. they are easy to rebuild. seems like to me if I want more power and not alot of money(which I dont) then turbo is the way. and when I open the hood I will get that "what the hell engine is that" reaction that I LOVE.

 

[Blackbirdsrt78]

Now any ideas on a cam that would be good for what I'm talking about? I don't know very much at all about that sort of thing. I am guessing that I would have to know the RPM that achieves the most boost and select a cam that compliments that. I am guessing numbers will be needed.

 

[kkritsilas]

If wjhat you want is instant, street type horsepower, you should possilbly consider a supercharger instead of a turbo. SImpler set up, and no turbo lag, along with eatier to handle heat issues. THe smaller whipple style superhargers are also quite efficient in term of boost vs. drive horsepower. Biggest issues are mounting brackets, and amkeing sure that the blower drive is well engineered. You don't seem to be looking for ultimate HP, so a supercharger should work well.

For a supercharger (be sure to get the brackets, pulleys, and intercoole.r as well) you might want to look at the junkyards for GM donor cars. GM made a lot of 3800 supercharged cars, so there may be some around considering the number of different models from GM that had these engines in them. Should be approximately the right size, too (the slant 5 225 being a 3.8L, and the GMs being 3.8L). You would have to rig up a mounitng bracket, or modify whatever you get from the donor car, you will need a belt drive gear for the end of the slant's crank, and then a tube from the supercharger to the carb. Carb should be used reworked to allow for blow through operation.
Changing the pulley diameter on the supercharger will allow you to change boost levels.

Kostas

 

[greymouser7]

I think Rich wants cheaper power than the supercharger set up. thanks though

 

[greymouser7]

Now any ideas on a cam that would be good for what I'm talking about? I don't know very much at all about that sort of thing. I am guessing that I would have to know the RPM that achieves the most boost and select a cam that compliments that. I am guessing numbers will be needed.

the car mags' web sites have allot of write-ups about how turbo cams are different, but I am guessing, nothing in this realm will be cheap, or off the shelf because this is a unique set up

 

[Blackbirdsrt78]

the car mags' web sites have allot of write-ups about how turbo cams are different, but I am guessing, nothing in this realm will be cheap, or off the shelf because this is a unique set up

I need to run numbers into desktop dyno and see what is realistic

 

[kkritsilas]

Forced induction is never cheap. Doesn't matter what engine, doesn't matter what form (turbo or supercharging).

With the availability of hte junkyard GM superchargers, it will be a lot easier than trying to get a turbo setup, from the basics (unless you can find a Grand National/GNX turbo cheap, of course, or a pair of turbos from a Dodge Steatlh/Mitubish VR2000, or the Nissan 300ZX Turbo) like the boost unit itself, to all the bits that need fabricating (like a bracket to hold the turbo, plumbing (which was touched on previously regarding the exhaust manifold welding) and the need to manage the underhood heat (exhanust tubing into the turbo's turbine, back out to the exhaust, all with pipeing/tubing that can take exhaust temperatures and survive exhaus gasess) and the intake plumbing, along with an oil tube for the center bearing of the turbo. A supercharged setup needs intake plumbing, and a drive belt. No exhaust plumbing with the exotic/expensive tubing, no added on oil lines (the GM supercharger uses its own supply, separate from the engine oil supply). Cooler air coming out of the supercharger may eliminate need for an intercooler. Only big issue is the brackets (which are needed for the turbo setup as well) and the drive belt setup. In return, you get a more streetable setup.

Also, consider this: For the Hellcat, Dodge/Chrysler/FCA went with a supercharger. Ever wonder why? They have all the engineering resources needed to come up with a turbo, or twin turbo setup: engineers, programmers, parts sources, etc. Yet they went with a supercharger for its driveability. They probably could have had more power output with a turbo setup. But it wouldn't work as well as a supercharger, ON THE STREET. On the street was what blackbirdsrt78 was asking for.

Kostas

 

[Jack Meoff]

http://youtu.be/iSIsCAGV7A0

 

[kkritsilas]

Eaton M90 in the video is the same supercharger from a GM supercharged 3800 V6.

Did the torque ever jump. HP went up from 91.9 to 163.6, but torque went from 228.9 to 473.9. That is Big Block level torque. HP was up nicely, but the long stroke and the boost must have combined to work really well. HP went up by 78%, but Torque went up 107%.

Kostas

 

[Blackbirdsrt78]

was that common option on a GM 3800 I had a 91 cutlass supreme but no super charger. What cars should I be looking for to pull one of those bad boys.

 

[Blackbirdsrt78]

Did the torque ever jump. HP went up from 91.9 to 163.6, but torque went from 228.9 to 473.9. That is Big Block level torque. HP was up nicely, but the long stroke and the boost must have combined to work really well. HP went up by 78%, but Torque went up 107%.

Kostas

that is an amazing power increase. it would be time for a new rearend I dont think the 7.25 can take that much torque for long.

 

[Blackbirdsrt78]

would need an offy intake and a good 4 bbl. I am going to have to look at what cam to use but those numbers are exactly what I was planning on having to the wheels when you have almost 500 ft lbs of torque 160 hp is plenty power to get the car going. I am curious why the HP is so low though. then again those numbers are to the wheels(brake HP) so at the flywheel it s\would be closer to 200. not bad at all. :naka:

 

[Blackbirdsrt78]

Desktop dyno says this is gonna be cool. the numbers dont lie forced induction is the way to go on a slant. maybe i could use the A/C brakets and install the blower where the AC would go. These numbers are for a slant bored .030 with 10:1 compression ratio, 1.7 intake valve 1.4 exhaust valve diameter, pocket ported head, the only thing I have left to figure is the cam profile. i just auto calculated it for the sake of seeing what is possible. A larger carb will be in order as well.

 

[Blackbirdsrt78]

https://www.youtube.com/watch?v=KYMkPjt4AOA

 

[Blackbirdsrt78]

http://www.ebay.com/itm/Eaton-M90-S...Parts_Accessories&hash=item3cefa215ec&vxp=mtr

 

[kkritsilas]

Blackbird79:

With 450+ Ft. Lbs of torque, you should realistically be looking at an 8 3/4", and maybe even a six cylinder version of a 727. It isn't horsepower that breaks rear ends/differentials; its torque, and the torque out of the supercharged slant six is at big block levels, and the big blocks will shred an A904, or 7.25", and probably (over time), destroy an 8.25" rear as well.

Most GM car lines had at least one supercharged variant. The ones I know for sure are the Chev. Monte Carlo SS pre-2006, Pontiac Grand Prix GTP/GXP pre 2005, Buick Regal pre-2006. There are others, I am sure. I would try to get as new a unit as possible, the newer units are the Gen V(5)s, and are improved in a number of ways. You can look up ZZP (http://shop.zzperformance.com/); they have a ton of information on these superchargers in their tech articles section. According to them, the Gen 5 superchargers are good to about 15-16 psi. The supercharger in the Youtube video that Captain Caravelle posted was an Eaton M90 running at 10 psi.

HP is limited by RPM, and the undersquare design of the slant 6 (sort of the same thing, I guess). Engines make torque, HP is a derived number that uses RPM as a factor. The torque comes from the long stroke (almost as long as a big block's). Its like train locomotives: Massive diesels driving generators and then electric motors. HP:6250, Torque, 181,000-200,000 ft. lbs starting, 166,000 ft. lbs continuous. (all numbers for GE AC6000CW). Max. RPM is 1250.

Besides, the numbers are at the rear wheels, so 161.9 HP works out to right around 200 HP at the crankshaft, and even in the naturally aspirated slant 6, it makes larger torque numbers than HP numbers. I personally think that the boost pressure overcomes a lot of the breathing issues that undersquare engines have; with the engine able to take in more air and fuel, and fuel/air distribution being more even, the engine really comes alive. Same thing as the Harley V-Twins in drag bikes; for a while, the hot setup was a Japanese (usually Suzuki) 4 cylinder and turbo; now it is a V-Rod based V twin with a supercharger. I'm sure that there is a bunch of reasons for it, but end of the day, it just works. Just like the Slant 6 and a supercharger.

Kostas

 

[Blackbirdsrt78]

I think the 7.25 will be ok for a while. I'm not looking for 400+ torque I put in what I was thinking about on desktop dyno and it looks more like barely over 300Ft/lbs. at the flywheel. I have been looking at the supercharger and it looks like adapter plates and tubing have to be fab'd up. I think that changing the diameter of the pulley will give different boost levels. So I think I am going to shoot for 10 psi it will most likely be less than that. I am having trouble finding stuff to make the air ducting with and how to mate it to the supercharger. I will have to make brackets. and buy a serpentine crank pulley or pull one at a bone yard.

 

[kkritsilas]

you can always play with the pulley ratios to get the boost that you want. I was only talking about the 10 lbs boost because that is what the guy on the video was using to get his >450 Ft. Lbs. of torque. If you keep the boost levels lower (maybe 6-7 psi), you will get less power, but it won't be as hard on the other components, and your engine will live longer.

Kostas

 

[Blackbirdsrt78]

Yeah there has to be more the the story of that car making that much torque than just the super charger. It must have had some real extreme things done to it. I think it must have been over 10:1 compression. because 10 psi boost only gets the torque around 300 on desktop dyno.

 

[Blackbirdsrt78]

This is my first attempt at supercharging. So I have learned a few things there are "blow through" and "draw through" setups. the video that Captain Caravelle posted was draw through. I think that is the best way to go so that I wont have to buy a blow through carb or make funky tubing. Its looking more doable the more I look into this. to mate the carb to the intake I am going to need a 4 bbl intake, an adapter plate will need to be made and a way of mounting the carb to the intake side of the blower will have to be made. I'm not sure how much clearance there will be to shut the hood once its all in there so a hood scoop may be needed. I wish there were better views and pics of that setup.