To rebuild or not that is the question!
 

I am new to RX 7 racing, I was in Spec miata for 5 years. I just bought a street RX7 2nd gen 1991 with 66000 miles on it. the engine runs fine, a little white smoke at start up but once it is warmed up no smoke. My question is should I have the engine rebuilt or not ? I want to keep it stock so there would be no preformance mods that I would do. I don't know enough about these engines to know if you get much hp improvement with just a stock rebuild.

Any help for an RX7 newbie?

PS I do intend to race it.

I'm confused....you want to race it but want to keep it stock and do no performance mods? I guess that could be done but don't usually one would want to maxzimize power. What class you going to race?

Rebuild would be nice if it's in the budget and insure you don't have any problems. An ITS 2nd Gen needs to put out 175rwhp to be any good which comes from the right bolt on parts. If it was me, I'd rebuild it.

It's cheaper to rebuild before it dies completely, as the parts will only be worn and you won't have to replace other stuff due to damage of a blown seal or something.

66000 miles is very low. no need to rebuild, just put bolt ons and ull b fine

Thanks for the help, I will be racing in NASA and the class will require it to be stock. I can go with aftermarket intake and exhaust including header, any recommendations?

Also Are there things I need to know about getting rid of the AC and can you dump the power steering like I did with the miata, if so, any how tos?

with only 66k your totally fine

I'd do a compression test before deciding anything.

some people have no faith in rotaries

I don't think that the lack of faith is for the rotary, but for the previous owner's ignorance of the rotary.

I, too, would compression test the engine to determine whether or not to rebuild.

What do you plan to run in Nasa? I am currently an instructor, and plan to take the comp school in 08. I find that after prepping for SCCA ITS/CSP, I am 5-7 points into Nasa PTD. If you plan to race Nasa, get the classing information first, and build to spec. I'm sure I could have axed a couple of upgrades to remain in PTE.

My ITS was about 8 points into PTC, had to really trim back to run PTD. No way PTE was going to happen. Did you take points for the 4 pot calipers and LSD? You at 2680lbs? When the '08 rules come out it's time for a PT specific build.

Back on topic, what NASA class are you building for hawke3? I would assume PT which allows mild to wild on what you do. What class requires stock? If you got the money, rebuild, if you are on a limited budget and the engine compression is still good, hold off. Removing the AC and power steering - you'll find lots of threads in the 2nd Gen section on this forum with how to's. The best exhaust system for ITS was the one from ISC racing, although due to demand on 2nd Gen parts, he's stopped production on the expansion chamber. Two recommendations for ITS type parts is ISC Racing or Flatout motorsports. Both can help you put together an ITS type road race 2nd gen. There are lots and lots and lots of places to buy stuff, but I have found these two shops beneficial as they specialize in ITS 2nd Gen cars and race them. You aren't building ITS I know, but it's similar to what you describe for NASA.

My FC is an SE, so 4-pots, manual rack, and LSD were std- though I took points for changing the LSD. Truth is that I was only 90% through the ITS build, and started putting stuff back in (door panels - 2 pts EACH, OMG!) to benefit PT classing. I'm also planning on running RA-1s rather than my 710s, so there are 5more points back. I still have a passenger seat (for my students), too (3 pts). I haven't weighed the car in a while, but it would likely be under weight - it was 2550 full and wet, no driver 2 years ago as mostly stock.

Remember that the ISC exhaust is LOUD - well, all race FC exhausts are like that. Plan on completely removing your car from the street.

hawke3 - do you have any track experience, or will you be participating in an DE program? The build of the car can be gradual as you build your driving skill.

Not to hijack the thread, but this is related to a NASA build and the original poster is building for NASA...

I'm taking the 2pts for 4 pots and 3pts for the LSD (actually a 5.12 6pk clutch). That's 5 pts I don't want but do take. Greg the national PT director thinks you have take pts for everything, even though I think some are BS. The way I read the rules is the 4 pots and LSD require points since they were not standard on the base model from my research. I can't find a base model FC that came with 4 pots or LSD, am I mistaken? ..but I can put on aftermarket 2 piece rotors, save a few lbs on unsprung weight and not take a single point, ha!

"For purposes of NASA PT points assessments, the term OEM will be defined as follows: Any part that is identical in size, shape, and functional characteristics compared to the part that originally came on the vehicle, from the manufacturer, as a standard feature of the base model as it is listed in section 5.2 Base Classifications (factory options and specialty model parts are considered non-OEM)"

Help me out, how can I justify not taking those points? I'm not protesting you but rather looking for some advice on how I can not claim these. I hate these 5 points. I'd agree to 1pt for the modified LSD.

I have found the alternate weight method works better as my car is stripped. Here's something else, did you know the factory rear spoiler requires points? ....according to Greg since it wasn't on the base model, scrap that if you got it.


EDIT: I can't figure it out, was the 4 pot ever on a base model FC? The factory spec and feature list is confusing me.

Unfortunately, I'm pretty sure you are correct on all counts. I was reading a bit into the rules since the SE technically was a stripped model of the GXL package, thus being a type of 'base' model. I'd be confident to wager Greg et al will not accept it as such.

This revelation means I am now probably well into D :rolleyes:

To the OP: pay attention, the rules are 'interesting' ;)

Well that is a lot of info and i guess it shows my ingorance of this car and the class I was shooting for, PTE. I figured the engine would have to be stock because you need the points for intake (1) ,LSD (3),exhaust (5) suspension (7)and tires using 205 width you can save 7 points and use a 10 point tire that figures to 19. I suppose I missed something??

Yes as I mentioned I have been driving for 5 years in spec miata, anybody wanta buy one??? It finished on the podium in PTD at the Nationals

OP said this will be a racing engine.

One of the RX-7's strengths is the 4-pot brakes on the GXL, SE, etc that would require 2 points - you really don't want to race an FC without these. Also, the stock ECU is very limiting on the 5000 rpm plus region, which will require some level of intervention - either a piggy-back or a standalone. I know the ITS guys are running a fuel pressure regulator to remove fuel in the higher RPMs, but the new RTek is granting full timing and fuel control for a reasonable price.

You do not want to port the engine - 20 points is huge! BUT a properly tuned ITS engine (which is essentially stock with exhaust mods) should be putting 175 to the wheels. Unfortunately, NASA thinks a street port is ~180 rwhp, which requires 20 points. I have asked the question with no response so far, though in the TT section (which I will do prior to joining PT).

Then there is the game of 'weight reduction'. Calculate the points both ways for the best result. Door panel removal 2pts each - Passenger seat 3 pts - carpet 1 - aluminum hood 1. Some of the competitors are starting to ask for a lb/hp number for each class rather than having to play weight reduction game, but the powers that be seem disinclined to acquiesce.

One more thing I will say is that if you are building for PT, Todd Reid seems to take an effective philosophy - make power and buy good tires, the rest is fluff.

Good to see another FC getting into PT! To get your SM on the podium for PTD, was it in 100% SM trim or did you make some changes? Was it built 8/10 or 10/10 SM or ? Congrats by the way.

Here's how mine sits now in ITS/PT trim but will be redesigned solely for PT rules when '08 rule book is out. There are supposed to be some changes/clarifications to the points.

Base PTE - under 19pts, PTD 20-39, PTC 40-59, etc

Tires - most the FC's, in fact all I've heard of run 225/45/15 or 225/50/15. I hadn't thought of the 205, however maybe you have some left from SM days. I took 4 pts, 5 for RA-1 less 1 for size = 4. Really need to put Hoosiers on so got to find another 5 pts. Total 4

Weight - I didn't see anything you had for weight unless you were going to run 2800#, but then I don't how you can do that without adding more than 150# ballast which is max allowed. Alt. method got me 8 pts, curb of 2800-2680 comp (ITS comp weight, and I got 150# ballast) = 120lbs Total 8

Engine/drivetrain - 1pt for pulley, you'll want an underdrive pulley or will cavitate your water pump. 1pt for air intake. 2pts for FPR - that and timing is about all you can do to tune these without doing a standalone ECU. 5pts exhaust. 3pts added LSD (see discussion above). Total 12

Suspension - 3pts shocks, 2pts springs. Remove rear sway bar, spherical joints front bar - 2pts, 4 pot calipers - 2pts (see discussion above), 3pts metallic suspension bushings (waste of points, I'm removing these), 1pt front strut bar. Total 13

Aerodynamics - 2-6pts, debate over how many I should take for the splitter/air dam. The main purpose for this is the FC is very hard to keep cool, you need all the air you can get even with an expensive and fancy radiator. It took me months to get the right setup to keep the temps in line. Taking only 2pts for now.

That's 39pts, possibly 43 with splitter pts debate. Add on Hoosiers and we are 48, take off spherical bearings and back to 45. As you can see, it's going to be hard to keep an FC in PTE, heck I struggle for PTD, even with limited mods. You've left out some critical must have items I'm not sure you can go without. I do agree you are better running a non-ported motor, the street port is 20pts with an estimated rwhp by NASA of 180rwhp. You should be able to get to about that # with a good ITS type motor, which won't cost nearly that many points. There are some no points items that look very attractive as well. Hope this helps some.

Well, this is discouraging but, I appreciate the sound advice. I think I have to agree with you that a properly equiped car will be in PTD. I am just afraid that these cars cannot be competitive in this class when it reaches its potential. There are just too many newer race cars that have the potential to dominate. Even the PTE fastest lap at the Nationals was 141 something and the track record for ITS is 142 something let alone what a well prepared PTD Honda or BMW will do.

The 95 miata was SM trim plus a header and an intake but that was all. But as I said above PTD is not near its potential( PTE times were nearly 2 seconds faster than PTD) and it seems that there is significant interest in PT for next year.

So I guess I will need to rethink this whole thing.

A "street port" is all that's allowed in EP racing and they get to over 200whp. Only the very most powerful ITS cars are getting into the 170whp range.

I tracked my FC with solid rear rotors at Pacific Raceways in Seattle with street tires and they faded. You definetly want the vented rears and the 4 piston fronts are nicer than the sliding calipers.

SCCAITS are you not using an aftermarket front sway bar?

..that's discouraging, but the PT rules are being revised so who knows, maybe things will get worked out. There is a push from some to bring PT rules more in line with IT rules but I disagree. NASA does not need to try and mirror the rules of SCCA or create rules that make an IT car a front runner without any changes.

Stock front bar with adjustable links, no rear bar. I'm running a stiffer spring than most (# not disclosed) and custom double adjustable Koni's all around - those make a big difference. This wasn't by my design but that of a SCCA Pro Racing champion who does the setup/testing on my car... I figure he knows alot more than I do!

Acording to the spec sheet the 1991 weights 2725 so I can take off my weight 200 lbs plus 25 and still weight in at 2800 under the alt method(I will also have to include the weight of the roll cage) or take off more and add ballast or do I still have the weight rule confused again?

FC weights w/manual trans from published specifications and features:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/specifications-what-did-2nd-generation-rx-7-come-w-options-standard-features-642372/

86 - 2625
87 - 2700
88 - 2720
89-90 - 2800
91 - 2787

I am a little alarmed that the FC needs to meet 2800 lbs min comp weight. The listed 86 curb weight is 2625 in the brochure, but 2800 in the PT rules.

Interestingly, the Turbo II min PT weight is 2775!!!

If it weighs 2725 and then you sit in it (200lbs), you are at 2925. Any amount under 2800 (you + car) is going to cost you points. Right off the bat you could take out 125lbs, then you add a cage which is heavy and then take out more parts.

Keep this in mind, my car (2350 dry) and I (180) is only 2530 and I need to be at 2800. Add 150 ballast and that is 2680 + a little end of race fuel for 10-15lbs. That's still 100+lbs short or 8pts. Max ballast is 150lbs. These cars get below the 2800 quick and easy, I think the 2800 would be hard to obtain unless you added ballast and/or didn't strip much (like a Showroom Stock car). Remember my weights are ITS trim - stock body, glass, etc. (though admittedly stripped beyond what the washer bottle rules guys accept, thus another reason to go ITE)

I guess if you are still shooting for PTE you would need the 2800, otherwise with PTD you should be able to have a few points to give up for weight.