Alright, I've used the search function, and I still haven't quite found the info I'm looking for. But before I get into my questions, let me first explain my situation.

I'm a Honda man at heart, but I've always wanted an RX 7 ( I actually passed up an FD to buy my Porsche, I honestly regret that). Anyways, a friend at work has an 86 N/A 13B. He's got too many cars, and his wife wants him to get rid of it. It's got about 100k on it, clutch and clutch master cyl were just replaced. Only things it needs are front and rear struts, and a power steering rack. He said he'll sell it for $400, and coincidently, I happen to have about 500 laying around.

He knows his **** when it comes to cars, arguably the most knowledgable person I've met. However, he was raised on American Muscle, so he told me he rarely takes it aboce 5k (RPM's). Now from the hours of research I have crammed into these last couple of days, thats not a good thing.

So I'm going to take it on a test drive on sunday, so I'm wondering what things I should specifically be on the lookout for considering these facts (I have read the N/A Buying Guide, but I'd like a little bit more specific info on what this lack of revving could have caused).


And Finally, a few tech questions I just couldn't find:
1) Can S5 rotors fit/work in an S4 housing?
2) If so, will I need to run and S5 ecu in order for it run correctly?
3) I am planning for this to be my new autocross car next year, so is 225rwhp, emissions legal, out of the question N/A for about 5 grand?
4) If not, those who have autoxed TII's, is it hard to keep it in the powerband, and would 250 rwhp emmissions legal be possible with a TII swap?


Thanks in advance, and hopefully if all goes well, I'll be a proud FC owner in the next few weeks

 

1) yes
2)no
3)might as well swap to TII
4)noyes

 

thanks. Why a no/yes on 250 rwhp emissions legal?

 

3. Big no
4. Depends on where you live but a catback with a few other goodies could take you there.

 

1) Yes. Rotors are swappable, but the big hp gain on the S5 NA is the VDI valve on the UIM, not so much the 9.7 vs. 9.4 compression ratios.
2) No ECU change needed if you switch rotors or even the whole short block.
3) 225 rwhp on an NA is not possible without some serious porting and changes to run at higher RPM. And it will not pass smog at all, let alone be streetable. 160 to 175 rwhp is a more reasonable goal.
4) No idea on autox with a TII. 250 rwhp is possible, but likely with a bigger turbo.

As far as the previous owner of the NA you're looking to buy not taking it above 5k RPM, that's really not a big deal. The aux ports open at 3.8k, so as long as he took it above that regularly, you probably won't have to worry about stuck actuators. Even so, if the aux port system has a leaking gasket or he installed a free-flowing exhaust system, they will likely not be functional (just not necessarily frozen). Look for a strong steady pull all the way to redline; it should not drop off past 5k.

 

thanks alot. Also, the swap threads on here seem to be pieced together engines, so will a S5 TII engine bolt right in to the current motor and transmission mounts?

 

Any S4/S5 motor will bolt onto the same motor mounts, and the bell housing bolt patterns are identical, but not the flywheels. Going outside your series will require rewiring of the instrument cluster harness however, so for ease you can use an S4 TII. Or an S5 short block with S4 front cover / flywheel / manifolds & sensors.

You can use the NA tranny with the TII motor if you put the NA flywheel on it, but it's not recommended since the TII tranny is much stronger and can handle the power better.

 

Yes. As mentioned the compression is higher. They are also lighter so you will need the counterweight and flywheel from the S5 (or an aftermarket flywheel) to keep the assembly balanced. They are better for higher RPM operation but won't result in much power increase.

Nope.

Never. Making 200HP on the NA 13B without aggressive porting is rare and certainly never emissions legal.

Yep. Use a high flow cat, keep the emissions system in tact and crank the boost with appropriate fuel upgrades. 250HP is about the limit of the stock turbo.