Hey all.

I have an engine swap planned for my 71 Monte Carlo and I've always wanted to twin turbo it. Now is the time to begin planning and assembling parts. So without further ado, here is what I have.

1971 Monte Carlo.
454 bbc w/ ported aluminum heads
Full fiberglass front end
Built 700r4 transmission
Built 12 bolt 3:73 posi

My plan is to keep with the 454 or stroke it to 496. Either way, a fully forged short block is on the list. I haven't decided if I want to go blow through with a carb or make the switch to EFI. Nor do I know what turbos I should run, but I'm only looking for a modest ~800hp low boost build with driveability being a major factor in choosing components. This vehicle will spend most of its time on the street with occasional track duty. That being said EFI is probably the best option and I would probably run E85 if I go that direction. I'm not looking at a huge budget, but I'm also not looking at skimping on the more important pieces to this build. I will use this thread to chronicle my journey and I've already been reading some threads on this forum in research. Lots of information.

Right now, I'm looking at some CXracing kits and determining if it's worth it to start with one of those or start completely from scratch. I don't have fabrication skills, but I have friends that do. I'm mechanically inclined and well versed in engine management so I hope I'm not in over my head. Any suggestions or other threads to look into, I'm definitely open to hearing as this will be my first turbo build.

Here's a pic of the car I refer to as the Dark Knight. Tell me this thing isn't begging for some twins under the hood.

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Yes, twins. I have always loved that body monte, looking forward to watching you build it.

 

That thing is stunning. Excited to see the progress.

 

I'm thinking of starting with this kit.
http://www.cxracing.com/mm5/merchan...ode=TRB-KIT-BBC-CHEVELLE-NO-IC&Category_Code=

I'd have to come up with my own intercooler setup but that's doable. My concern is the quality of the turbos and wastegates at this price. Any thoughts?

 

Ditch the 700R-4. It will never last, and it's not going to want to make a clean 2-3 upshift at wide open throttle with that much power going through it.

Also ditch the 3.73 gear ratio.

If you're on a budget, go for a 3.08 or 3.31 gear set, and a TH400. If you really want an overdrive transmission then a 4L80E is your only option at your power level and weight.

 

The 700r4 is probably not up to the task, but this will mainly be street driven with occasional track duty. When the time comes, I will make the necessary changes. Thanks for the tip.

First things first. I need to plan a long block build. My current engine will be sold to help with funds and with 10.5+ CR, it's just not ideal to boost. I'll keep it under 9:1 CR and fully forged components. Initially, I'm thinking Patriot aluminum 320cc heads and a turbo grind roller cam. Anybody see any issues with that?

 

Well, spending some time researching yielded some changes to my original plan. Instead of building an engine, I think I am going to boost my existing engine. Originally, I figured that my 10+CR was too high, but apparently, when running lower boost turbo setups, it's ideal because better torque, less lag, all resulting in better response across the board. So instead of initially spending money to build a short block, my money will be better spent purchasing a complete turnkey EFI system. I'll install that before I even add the turbo setup, learn the software since I'm familiar enough with the tuning process, and then I'll boost it. I'm finding that these EFI systems are pretty slick and they come with everything from the intake, throttle body, injectors, distributor, fuel pump and the list goes on. I'm leaning towards the FAST XFI. The price is pretty hefty at about $4gs but these systems can do everything, even flex fuel. You bet I'll run e85 and without worrying about the actual blend because it uses a GM fuel sensor just like modern vehicles. E85 will pair better with the higher compression and boost anyway so it's a win-win. I'll keep you this thread updated on the progress. Again, any other advice, I'm receptive.

 

Re: My '71 Monte (The Dark Knight) BB Twin Turbo "aspirations".

My 10.5:1 347 was awesome on low boost. 7 lbs yielded me a 12:52 in Denver, co on a 90 degree afternoon(track temps over 100), no intercooler, 18 degrees of timing, 91 octane and a T5, thru a carb.

- - - Updated - - -

I shouldn't say awesome. Respectable

 

Nice looking car.

Do some research on those headers....I have a hard time believing that #5 tube will clear the steering shaft....that was a major challenge when I made the headers in my build (BBC chevelle)...but my engine is lowered about 1/2".

Remember...the 66 chevelle they show in the pictures has the steering box behind the crossmember like a 1st gen camaro....your monte has the steering box in front of the crossmember (like any 68-72 A body)...completely different configurations for the steering shaft/header interference areas

Just a heads up

 

That's a good point. I hadn't considered that. I already have clearance issues with my current headers and that steering shaft. The photos show anything clear on that side of the vehicle to demonstrate this concern. I wonder if there's a way to find out for sure.. I may need to have some custom built. That's out of my area of expertise.

That is why I'm running this by others first before making any purchases.

Thanks for the advice.

 

That's not correct. NO Chevelle had "rear steer"...maybe your thinking of the Nova that started out behind & then later went to front steer?
I looked at the photos of the car in the link to check to be sure that this particular car wasn't changed to a rack or something & you can see the steering box in the factory location in the photo in the last row...first picture. Hope this helps, Lorne

 

So what you think is there is a chance of running these headers on my 71 Monte without fabrication? I really like the way this kit is configured, however, the more I read, it looks like trying to run it intercooler will be more of a problem than it is worth. Besides, since I plan in tuning it for lower boost, would an intercooler even make much difference?

 

good correction.

 

Okay. First piece of equipment purchased.

After much deliberation, I ended up purchasing the FiTech EFI 1200hp to provide my fueling needs. As stated, I will get my N/A engine up and running on this EFI before I add the turbos. That'll give me some time to learn the software, choose a setup, and continue to save more money for everything.

My EFI kit should be here by the end of the week, so in the meantime, I'll be deciding the direction I need to go with the fueling needs of the EFI.

I'm really excited to get this thing going on EFI. I'm a self-tuner of my 400+whp turbo Subaru. It literally makes double the power as it was stock and I'm still running stock internals. Hopefully my abilities where that vehicle is concerned carries over to this vehicle. Tuning with the carb has always been a bit of a shot in the dark. EFI is so much more definitive.

Anyway, stay "tuned" .....yeah, that's bad.

 

subbing and looking forward to the build

Agree with others the 700r4 will not survive long term

as for compression - it will help off boost manners - just be aware with more compression there is less room for tuning error. start conservative and work your way up.

 

Re: My '71 Monte (The Dark Knight) BB Twin Turbo "aspirations".

No doubt. That's why I'm ultimately going to run E85. It's vastly advantageous especially for a turbocharged application to keep temps down and its knock prevention attributes.

But yes, still keeping it conservative. That's how I tuned my other car. I've learned that you make ONLY 1 small change at a time.

 

Very cool project and please post more pics of the car!!! What is it running now in the quarter mile?

 

Thanks! Unfortunately, I haven't been to the track since the vehicle has been completed (well, never really done) some 4 years ago.

On another note, I should blame you for what I'm embarking on now. Some time ago, I noticed your Skylark (one of my top 3 favorite muscle cars) for sale and thought to myself how badass these muscle car era vehicles are fitted with twins. I haven't stopped thinking about doing this to mine since then. Originally, I was just going to do an engine swap to a big inch big block, but I like being unique and set apart. Enjoy a few more photos and I'll be visiting your thread.

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WOW, that is super cool that my car inspired your car! I was sick to my stomach when my car went up for sale and I could not buy it at the time... Thank goodness the new owner sold me the car later on.

AND WOW the car looks amazing!

 

Thanks. What's going to be a real challenge is keeping everything under the hood clean. Everything is tucked out of sight for underhood eye appeal and I'm looking to keep the theme and color scheme intact. The vehicle is multipurpose in that I like it to be enjoyable on cruises especially with the wife and three kids, tire blistering power, and a show stopper at the local events. All the while, I like to have something a little different and unique. Obviously, it's tough to wrap this all in one package so compromises must be made.