kingyeddi

Sorry if this has been asked before, but I used the search, and its not working for me. It might just be my computer.

Anyways, I've located running (87ish) N/A RX7 for $100 setting up in a guys backyard. It needs a tranny and some TLC, but its mostly complete. I'm familiar with DIY turbo setups and I'd like to build a kit for this.

I've seen a couple threads here about turboing non turbo 13b's but I want to know what the maximum boost I could run with [xxx] turbo and the right fuel system upgrades, intercooled. I'd like to run 17-20psi if its possible at the track/races and probaly just run about 10# on the streets.

If 17-20# is too much, then whats the max? What kind of HP#s should it put to the wheels? Just want a ballpark figure to make sure it'll even be worth trying. Please reccomend some off the shelf turbos that would suit the job.

Thanks

Kingofl337

Maybe you should be more concerned about getting the car moving under its own power before you try and find out how far you can push a motor with 1xx,xxx miles on it. If the tranny is bad you should look for a TurboII tranny to replace the N/A unit.

Unless the motor is fresh you probably won't make it over 300rwhp before you crack and apex seal if your good. So, budget a rebuild. Check out Arron Cakes website.

Aaron Cake

iTrader: (1)

Please read the FAQ. There is massive amounts of turbo-NA info.

As for your plan, 17-20PSI is a really bad idea on the stock turbo. After about 14PSI, the turbo is way past it's efficiency point, essentially just heating the air, and puking oil at the same time.

Now, if you are talking about a different turbo, then that's obviously a different story. You can run those kind of pressures, but as always (in ANY engine) tuning and properly building the engine becomes critical. It's very doubtfull that either the turbo or NA block (they're the same structurally) will support that kind of abuse without at least doweling. Now I have not run that kind of boost, so I hope someone who has will chime in.

You can pull 300HP out of the NA block with the stock TII turbo...That's good for mid 12s. How much power do you need?

Just dumping more boost into an engine won't necessarily make the car faster. If you're looking for more power, then you're into porting and turbo upgrades. Once you have the foundation down (and a good EMS) then the sky is the limit.

Again, please read both the FAQ and the archives. This question is asked about 100x per week.

kingyeddi

Maybe we should stick to the topic Not to be a dick, but the tranny has nothing to do with the maximum boost into a N/A 13b, the related problems or estimated power. You might think its dumb to ask this before the car is 'moving under its own power', but for example if you guys came in and said "it'll crap out @ 225RWHP", then I'd leave the pile of **** where it is and save the headache. See As far as it having a billion miles on it, I dont care. A rebuild in the future wouldnt be a problem. If the **** blows up, I'll just unbolt my kit and drop in a rebuilt motor. No big deal
I read it awhile back, probably overdue for a re-read :o
Trust me, theres no way I would fab up a custom kit just to use a stock turbo. Thats why I said 'with [xxx] turbo...' as in "instert here". I'm open for suggestions!!
So 20psi and a big turbo will work with the N/A motors stock compression? When you say 'build' what does this entail?
Yeah, **** the stock turbos. "How much"? How much is possible? That is the question. I'm not worried about fueling, as I'll run a stand alone FMU and some big injectors. As far as the rebuild and porting, I'll hold off at 1st. I mean really if I blow it up what am I out of, $100?? Not even that much
Again, my fault. I didnt recall anybody running a N/A 13b with a bigger turbo and 15+psi. Maybe I just suck at the internet?

SonicRaT

iTrader: (6)

I do. I run a BNR stage 3 hybrid on a stock 6port block. 300hp on the stock turbo? flywheel maybe, rwhp that's going to be pushing it. The problem is you're asking the wrong questions, and are pretty ignorant about it. There isn't a 'max' or 'limit' just because it's an n/a motor, as Aaron tried to explain earlier, it's all about how it's tuned and setup. At about 350hp the dowels will need to be taken care of in the engine, this has little to do with it being an n/a. After that, the higher compression ratio just means you have less tolerance to work with on detonation, so the 'limit' is only as good as you tune it and build it. This is why this question is not capable of being answered. But, for entertainments sake, I've ran 21psi and lived to talk about it. Use a hybrid turbo if your aims are in the 300 range, it's definatly cheaper, however does require some more work to make function properly, or just go with a standard full turbo any of the tII guys run (t04e/etc)

Aaron Cake

iTrader: (1)

Sure...As always, it's mostly a function of tuning. Don't expect to put that kind of boost into an engine with 150,000+ miles on it. And if you're looking to make power, you will need to get into porting.

Just curious, but what is the reason you want to run "20 PSI"? I've seen FCs running the popular TO4E "60-1" combination put down 400HP on a dyno at 12 PSI. A 400HP 2nd gen is an absolute beast of a car...

What is possible depends on your goals and how much you want to spend. You can have a 1000HP if you want, but it will cost you.

There have been a few around, but I don't know if they're in the FAQ. A search may turn them up, but that means sorting through all the NA-turbo threads (which is probably a good idea anyway...lots of info).

eViLRotor

iTrader: (2)

You magical number of 20 psi will not work on Pump gas either.
There are a few guys that run that pressure on pump but they don't have your high compression engine, and really know what they are doing.

100 Octane minimum.

kingyeddi

Cool. Looks like I'll go ahead and buy it. I'll buy a tranny, fab up the turbo kit and get it running and go from there (rebuild, porting etc).
Sweet, I'll look into the 60-1 line.
Yeah, I dont want to get too crazy. Want to keep the stock rotors.

Thanks to all that have replied, (some being much more helpful than others ) Youve helped me make the descision to go ahead and buy my 1st RX7

Just for discussions sake, would anybody mind posting up the recipie for a big horsepower [turbo] N/A 13b??

Aaron Cake

iTrader: (1)

I cleaned up the useless posts from this thread. If you don't have something useful to contribute, don't post.

Sounds like a plan.

The 60-1 refers to the compressor used, which is normally paired with some varient of the TO4 hot side. Seems to be a popular combination right now, and proven successful.

The stock rotors should be good for anything you want to do. There's nothing fundamental about the rotors that limit power. In fact, newer rotors are thinner, and have been known to dent and/or collapse in high boost engines.

If you take a look at the archives, I have an engine build thread which covers my assembly of my small half-bridge turbo-NA engine. It will give you an idea of what's required. I don't know how much power it will make because as far as I know, no one has ever done that kind of setup before. Still not sure on what turbo I'll end up with either.

kingyeddi

Mr. Cake, you dont know how helpful youve been. Thanks Now I'm off to look for that thread you mentioned.