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Dual Turbo BBC!!

12K views 8 replies 6 participants last post by  TurboS10  
#1 ·
Below are some pics of the dual turbo BBC we built at work. Well I shouldn't say WE, I came in late in the project an just worked on plumbing the intake side of the turbos and some on the oil return lines. Anyhow, this is just a gunie pig, hence the PVC intake tubes. It is a stock 454 and the intent was to build it, see how much power it made, and then use the same set up on a purpose built engine. Within the next two or three weeks we should have it in a car and be able to make some dyno pulles and she how she does. I'll keep you guys updated on the progress. Almost forgot, if anyone wants closer pics of any particular component just let me know. Also if you have any questions just ask and I'll do my best to answer them.




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#4 ·
Here is the deal. We don't know how much boost we are making and no it is not set up for turbo charging, it is a stock motor with a bigger carb, headers and two turbos. I can tell you that just free revving on the engine stand it was making enough pressure blow gasoline out of the float bowl seals :thumbup: I'm not sure if the next step it to install a boost gauge or to drop it in car and make a few runs on the chassis dyno. I think we should skip the gauge and just make some pulls, but that is just my opinion. I missed a few things in my first post; the turbos are off a couple of Grand Nationals and on the finished product will use three inch exhaust tubing instead of PVC.
 
#5 · (Edited)
Just a couple words of wisdom.....

You need to check your oil return lines. It looks like they may go level to up hill at the engine. Since the oil comes out of the turbos a frothy goop it could have drain problems getting back to the pan. This can cause the turbos to leak oil out the seals since they are not designed to hold back pressure.

Another thing is the wastegates.....I dont see any. Without boost control you will over spin those turbos and probably frag them and the engine. This is especially true since those turbos are really a little too small for that engine. If I were you I would not stand too close when it starts to rev.

I really hope someone has done some homework on the setup. If not, you will only have pieces of that engine left when the turbos over boost and send the pistons to the happy racing grounds. Make damn sure that carb is super fat on the jets at first. You need to easy a turbo engine into its correct AFR. Too lean for just a second is a second too long. I would also hope that the throttle shafts have been sealed. If not they will be leaking air and fuel........hope there are no spark plug wires burned at this point.

Another note is that you need to consider using much smaller intake piping. The large the pipe the more lag you will see. Typically just a little larger than the inside of the compressor discharge area is what you need. I am only using one 3 inch tube for my turbo which is much larger than the two of those put together.

I am not trying to be negative, just make you aware that there has to be some real considerations on the setup for a turbocharged engine. On a higher note, The header fabrication is pretty awesome. The setup looks nice, I would just check the things I mentioned.

Chris
 
#8 ·
It's actually going in a gutted 78 cutlass. It is a drag car that has been put on a major diet. Width wise it is OK but the hood clearance will be a problem, we'll have to figure something out there.

Thanks for pointing out some problems Chris. I was just showing the guy who built the motor your picture album yesterday. He was quite impressed, I might be PM 'ing you next week with a list of questions about your set up. I'll take a look at the drain back issue on Monday. Also waste gates are coming this week.
 
#9 ·
Barz51 said:

Thanks for pointing out some problems Chris. I was just showing the guy who built the motor your picture album yesterday. He was quite impressed, I might be PM 'ing you next week with a list of questions about your set up. I'll take a look at the drain back issue on Monday. Also waste gates are coming this week.
Feel free to PM or email me with any questions. Since I now have my engine running and it has seen boost, I can now say my design theory is sound. Good to hear on the wastegates. You guys really need to look into carb modifications if you have not. There are some maditory changes for boosted engines. It is not an option......

Let me know.

Chris