RX7Club.com - Mazda RX7 Forum - Race Car Tech

50mm PP port intake length?

FD Wheel Covers In Carbon — Sun, 17 May 2026 05:56:09 GMT

Working on a 50mm PP port project, N/A.

Anyone have good intake length numbers? We will try a few, but don�t want to start blindly

RX8 Six Speed Advice

Jeff76 — Wed, 13 May 2026 22:46:57 GMT

My old N/A five speed in my 87 GXL has seen better days. I have needed a clutch since I bought the car 30,000+ miles and twenty plus years ago. I am also having some syncro issues, too. Synthetic oil in about 400+ miles of driving seems to have helped some. I am not really ready to pass judgement quite yet.

I am looking to get an S1 RX8 gear box. I know that a S1 is weaker and geared differently than and S2. I will need mounts, t2 clutch, an extension for the shifter, driveshaft, etc. However, for a cheap price of $250, I can get one.

Should I just wait for an S2/buy new or just live with the old box and get an new clutch? Certainly, it would be cheaper, easier to just do the clutch. Let's just set aside cost for the moment and decide that way. Is a scrap yard S1 too risky to buy? It could break quickly or already have issues.

Also, I have a 3.9 rear to pair with the new gearbox. I would like to track the car at some point.

S4 Engine Options

Jeff76 — Wed, 13 May 2026 22:12:07 GMT

I am looking for some advice from those who build/use race engines. I currently have a 87 GXL, bone stock. It has about 120,000 miles on the original engine. Miraculously, it has compression numbers around 130 or so properly calibrated for speed and altitude. I would like to pull this engine at some point before it dies and rebuild it before something bad happens and trashes hard to get parts.

I do have a spare, ran when pulled S4 engine with roughly the same miles. I was considering rebuilding it, staying N/A with mods and going stand alone. However, with how hard the s4 parts are becoming to get, I think that I should buy something else like, a six port junk yard Renesis. Hoping to save good working unmodified S4 keg, etc.

I do realize that the lower intake of a Renesis will need either the stock ECU or Haltech. However with tech being what it is today, there might be aftermarket options for upper and lower intakes. Most likely not N/A though.

So, what would you do? Mod the S4 or save it? I know cost will be a big player here. Let's just put the cost issue toward the bottom of the worry pile and start there. Also, it would be nice to track the car at some point but also keeping it street legal. Thanks in advance for your thoughts.

(Just as a side note, I will likely be getting a RX8 six speed to pair with my extra 3.9 rear gear at some point, too.)

My Custom titanium muffler blow a hole at track

diyman25 — Fri, 24 Apr 2026 16:03:25 GMT

13B RE full bridge port FC
Car feel slower and sound weird at today track testing, was thinking have bad tank gas , all the sudden I was surrounded by cloud of smoke and see spark underneath the car ,
Pull off at runoff area , only discoverer my custom exhaust is in cherry red with giant hole !!! And my interior is at fire from those high temperatures silencer material, glad I was able to pull off fire before it get out of control

Muffler lifespan for track and race cars?

Valkyrie — Wed, 22 Apr 2026 01:28:18 GMT

How long should a muffler (or more specificallly, the filling) last on a single-turbo track/race car?