Hi. I am new to car modding and would like some help from pros

Hi. I’m new to car modding and am planning out my choice for mods for my 1973 Plymouth Roadrunner that I am going to be buying and doing all the mods to. I am struggling to pick out a turbocharger and radiator as of right now. I might ask about more later on since I want to try to do this on my own I’m just completely stumped on what to choose for these 2. I am planning on putting a ZZ572 Deluxe Big Block Chevy motor in it with 621 horsepower. I used a calculator to get the info that I would need to choose a turbocharger and it said that I would need a minimum of a 17 PSI boost, at least 132 pounds of air per minute, and at least 1636 CFM. Is this combination even possible? Please let me know. Also, I was just planning on using the measurements for a regular sized radiator for the roadrunner.

You’re ‘new to car modding’ and trying to combine several difficult mods at once? Why? I would rather get a high-output Mopar engine in there, no turbo, and go from there.

I would do that but my friend and I are planning on doing a competition type car modding series on youtube kinda like HiLow from Doughnut Media but without the price differences. Pretty much we are seeing who can make the best car without breaking $100k.

First things first. Get your hands on the car and figure out what’s broken. Fix that before you do anything else. Then upgrade the brakes and suspension, because if you’re going to make the car faster, it should also be able to stop and turn better so you don’t wreck. And if you’re planning on north of 600 horsepower, it’d be a really good idea to put a proper cage and 5 point harness in that thing, because cars with that much power, especially on older less-sharp-handling platforms, are a really good way to kill yourself if you don’t make 'em safe first.

I’m not all that up on Mopar engines, but in the engines I mess with, if you want to run 17 pounds of boost you need to build up the internals or it will fail spectacularly. So make sure the engine is sorted before you start thinking about boost.

Beyond all that, it’s somewhat baffling to me why you would pick a “less than $100,000” budget for your first build. Most people knock at least one zero off of that for their first time out. You’re going to make mistakes. Probably a lot of them. It’s a lot better to make 3-figure mistakes than 5-figure mistakes.


The car is all fixed up and everything since my grandpa is giving it to me as a present and the only reason I know about it is because he wanted to know what cars I liked and took me with him when he went to go pick it up.I already have suspension picked out as well as brakes and the roadrunner came with a cage and I already have a 5 point harness on my list of things. What internals would I need to work on for it to be proper for 17 pounds of boost? The $100,000 budget is for everything put together. Also my friend and I are more on the crazy side when it comes to planning for stuff like this and want to have a car that is practically all aftermarket parts for max power.

I mean, if you want max power, just put a Tesla drivetrain in the thing… :wink:

You’re on the wrong forum. You need to find some engine builder’s forum, but even then the frankencar you’re contemplating will need LOTS of very detailed planning. How many of them are there in the world? Any?

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Isn’t that just for electric cars tho? Also, we want to see who can come up with pretty much what would be the best price/hp. We may want more horsepower but it is also kinda like getting bragging rights in our families since we both have families with Mechanic backgrounds. I would ask my uncle for help since he is doing this type of thing to a Chevy Nova but he is never around since he is working all the time.

@texases is right. This is a car repair forum. Some of us mod cars, but I don’t think any of us have done anything on the order of what you’re proposing. Certainly not when we were brand new at car work.

What you’re proposing is somewhat like a guy deciding he wants to learn to fly airplanes, and for his first lesson plans to take an F-22 up and get into a full-on dogfight. You’re going to need a lot of expert help on this, and a lot of it will probably need to be in-person.

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Do you know of any forums like that?

There may be some info on google.com. Just a guess…

Well yeah that’s how I found this forum but I’m getting a bunch of other random crap besides.

You are going to need a serious transmission and rear axle for this.

You are starting with all the forged internals needed with this combo already from Chevy. The problem is adding a turbo with the engine’s base 12.5 compression ratio is going to burn a hole in all 8 pistons before you get off the dyno with 17 psi boost. It needs to more like 9:1 and the pistons need much thicker crowns. Needs a dry sump oiling system, too. It also needs electronic EVERYthing to manage the ignition and fuel to keep this thing alive. A carb is not going to cut it at 17 psi. The potential is about 1400 hp with 17 psi. You’ll need lots of dyno time with a pro tuning the ECU.

So given that, you need to upgrade everything in the driveline.

A Dana 60 rearend is an absolute must. With all the best parts you can find. The transmission most likely needs to be an automatic capable of accepting the 1400 ft-lbs the engine can deliver. That will take some serious work from someplace like Hughes Performance.

You are also going to need a massive radiator. As big as you can physically fit with as many rows as you can stand. You’ll only experience max hp for very short time, but that builds massive amounts of heat. And you’ll need a big oil cooler and a big trans cooler… forgot a BIG intercooler as well!

To get it all together is going to take lots of paid consultations from professionals that work in the performance industry.

Doing this as your first project is like deciding to build and launch your own space shuttle…Just sayin’


Assuming you’re not a Troll, the entire concept makes no sense.

You’re new to Moding but you’re planning doing a build on a 50 year old car with probably more HP than the Mopar engineers put in the all out Track Cars of that era?
To make it more interesting, you’re going to use a different engine and components than the car was designed to support?
And then you’re going to spend $100,000 to turn what at the time was an overpowered, poor handling family car into an even more overpowered, worse handling and now worthless family car, based on advice from the Net?

But giving you the benefit of the doubt and assuming you have a real interest in building cars, instead consider working really hard and earning a degree in Automotive Engineering from the University of Michigan or Clemson where you’ll actually see the future of performance and learn the craft.

And BTW, it’s not V8’s or even gas, it’s electric.

Beancounter I am not a troll. First of all my goal is to get over 1200 hp for as little as possible and I just assumed that a project like this would take like $100,000. Second I’m just trying to get a general idea on what I would need and I thought about asking people on forums because I assumed that people in car forums would have recommendations or at least point me in the right direction of what I would need. I already have plans to fix handling like I have performance air suspension picked out, I have performance tires picked out, I have performance coilers picked out, I have performance rims picked out, and I already have a roll cage on the list. I would consider the degree route but considering how expensive that would be I’m kinda iffy since I can get advice from pros.

Getting 1200 hp with any kind of reliability is a very difficult thing to try. Not a ‘bolt it together from the catalog’ proposition. Years ago we had a similar thread, but I’m not able to find it.

I know. It’s going to involve a lot of trial and error and a lot of money spent on consultations.

The thing is, trial and error here means you either have ready access to a dyno and the skills to make the needed changes, or you blow up the engine, maybe several times.

Have you looked around the Hot Rod Magazine web site for build articles?

I have looked up the Hot Rod magazine for articles. I also have ready access to a dyno since my uncle’s friend has a dyno in his shop.

And you got Flagged for profanity !