1984 RX-7 Race Car with BP! (almost a Miata)
 

Well my RX-7 has gone through a few changes since it became a full-time race car about 10 years ago. This time around though it is a ground-up rebuild of the chassis and the drive train.

Chassis:
- 1984 Mazda RX-7 GSL-SE
- GTM Wide Body
- Ford 9" Solid Axle Rearend w/ Floating Hubs
- 13" x 1.25" Brakes all around. 6 Piston calipers front, 4 pistons rear.
- Coil over suspension all around
- SMART GT Wing

Drivetrain:
- 1995 BP Block, 84.5 Wiseco pistons, Eagle H-Beam rods, ARP studs, lightened and balanced rotating
- 1999 Head, ported and polished
- 7.25" dual disc Tilton clutch
- RX-7 TII Transmission
- BEGi Intake Manifold
- Twin-Scroll exhaust manifold (working on it)
- BorgWarner 8374 TwinScroll internal wastegated
- WeaponX COPs
- MS3 + MS3x

I am sure I am forgetting stuff here. I am adding some more recent pictures of the progress and will update/add pictures as I continue.

power goals? Looks like awesome build! Man - seeing this really makes me wish I didn't haul my '84 gsl-se to the scrap yard years ago (before I was into racing)

Oh damn, this will be a fun one to watch.

The TII adapter plate is giving me wood. Don't be shy with the pictures now!

Very cool.

I have to ask though. Why the use of a 9" rear end. Isn't that power robbing overkill for your application? Am I to assume you had a very high powered motor in that chassis at one time?

Well the power goals are 450whp with a push to pass type of deal into the 500's. I will post more picture. I have lots!
As for the rearend I was originally looking into a quick-change. However it starts to get expensive to get something that can handle that much power since I have to look into Frankland and cannot use a spool. The 9" is definitely power robbing. Originally I was looking at the 8 3/4" Chrysler, but finding parts for the 9" was much easier.

Why are you going so big with the turbo? It seems like the 7064 or 7670 would be a much better choice giving you faster spool and both would still give you headroom over your 450 hp goal. They also both come in the same t4 twin scroll configuration as the 8374. Only reason I can see going so big is availabilty issues?

well spool is not too much of a factor since the car will be over 4000RPM. I just want to run lower boost pressure. I don't want to run around the track at 25+ PSI to make that goal power. I would much rather make that power at 18-19PSI.

Stop now, buy a Honda engine or SBC. Thank me later.

Why? If the turbo is in prime efficiency, who cares about MAP?

BTW, epic car and build. :bowdown:

That makes sense. Are you building the manifold yourself or hiring somebody to make it? Looking forward to seeing the build progress!

Well extra pressure means, extra issues. I have been tuning and driving turbo RX-7s and BP for over a decade. The less boost (within reason) that can achieve the HP goals, the less headaches.

I am most likely building it myself. I have definitely thought about having a Absurdflow done after I have drawn it in the solidworks since I have more room than a Miata. It will come down to having enough time during the holidays. I have the pipes and I have both flanges. So we will see!

Haha, yeah good idea!!!

Im in love. Cool car man

ls1

It had to be said....


This is a truly sweet build. Subscribed.

It is as much fun building the car as it is racing it!!!

I know... too many LS-1's and LS-7's these days. It has to be different. I rather beat the Porsches in a 1.8L (well 1.9L now) than a 5, 6, or 7L engine. Plus there is something to be said about a sexiness of a 4cylinder with the turbo and all the piping. Oh well this will be fun. It was either this or a 20B (tri rotor peripheral port). Decided to put the 20B in the upcoming tube chassis!

BAD-ASS!

Love it. I was going to suggest the v8 or honda options as well but the guys beat me to it. But it definitely looks like you know what you're doing, so either way it will turn out fast

Good luck and definitely don't skimp on the pictures

I see little notches cut in the cylinder head deck between the intake and exhaust valves.

Could you explain what that is for?

Also, elaborate on the knurling in the combustion chamber, looks like it was done with a center hole punch.

Glad to see someone with a lot of experience on here.

Singh grooves?

Yes, they are Sign grooves. What they are meant for is to get the flame front to the sides of the cylinder by the valves. That is where typically detonation on DOHC engines happen.

The trick with the knurling with the hole-punch is from a local drag race engine builder which is super smart (and actually helped Chrysler develop the new Hemi). It further reduces knocking and provides even flame-flow. I do not know the science behind that one, but I do trust him.

I've always viewed that as snake oil myself, I figure if I don't see an F1 head with those things.....

I do hope I'm wrong and everything works out great for you though!
Build looks great!

Yes, but we figured it should not degrade performance, so worth a try. That's why I kept them on the smaller side!

What color blue is the block? I like it!

It's Ford blue. I believe some older Mazda's have the same color on engine parts (mostly carb air cleaner cover)

Finished the front cage mount points. Hopefully can finish the cage this weekend!

Way to man up with the turbo. Thanks for sharing your build here. Looks awesome.

Thanks man! I am trying my best to be different, haha. Way more fun passing Daytona Porsches in a 4 cylinder turbo than a V8!

The cage is coming together very nicely. It will be pretty much done this week and I can work on the exhaust and turbo manifold after!

Any particular reason cell over OEM tank? That's a BIG cell... how many gallons?
I'd have nightmares of a leak followed by intense heat :eek:

Looking great - keep the pics coming

Well in SP and GT you have to run a fuel cell. Plus the cell is getting moved to where the passenger seat was. I would never run a race car on the track without fuel cell. That is a scary thought!
It is a 22-gallon cell. Quite a few racing series around the world have started mandating the cars to locate the fuel cell to the passenger compartment. It is a way safer area since it is inside the main structure of the roll cage instead of hanging off the back structure of the car. The V8 super car series are switching as well after that huge fire ball at Bathrust!

I will keep the picture coming. I have learned quite a bit over the years seeing other people projects, so hopefully this will give people some ideas for their own projects!

How do you mount 100lb of fuel and why not just use a keg?

well 22 gallons is just over 120lbs. It gets mounted pretty carefully! haha
It would be nice if it was a keg! unfortunately no booze on the track...

Passenger side door bars are done, driver side tomorrow!

this is the single ------- coolest thing I have seen all year. Subscribed.
(yea I know we're off to an early start on 2012, but thanks for making it magical.)

Thank you! That is good to hear.

I have couple of more picture. Tonight the rest of the cage will be done and on to mounting the fuel cell which I already have a cage for!

Very interesting and very cool! Props for uniqueness.

do you have any pics of the tranny apator plate being made? or just anymore pics of that being documented? im going to get a block tomm and i already have the t2 in my garage. i know what needs to be done, but moar pics=moar help.

oh and how thick is the plate that you used? and did you order your clutch through clutch.net? i think thats the easiest and cheapest option for us t2 tranny guys.

Well I got a lot of my information from couple of other guys on here. There is an active thread right now with TII in the name with quite a few pictures.
The plate is 1/2" aluminum. I am using tilton 7.25 dual disc clutch.

And all the bending is done and door bars are done on both sides. Started putting the fuel cell cage in.

can you send me the link? i cant find it. thanks.

where are you located btw?

You didn't really look hard, did you? haha

Here is one (welded plate): https://www.miataturbo.net/build-threads-57/build-thread-fe3-rx7-tii-efr-6258-ms3-58140/

Another one (bolted plate): https://www.miataturbo.net/build-threads-57/build-thread-tii-drivetrain-swap-built-motor-cage-widebody-blah-blah-19010/

For best results your will need a mill for the plate and lathe for the dowels.

I am in British Columbia, Canada eh :)

cool thanks. and ive already seen those links. so that would be why i couldnt find them

No worries. Good luck!

Cage is mostly done. Cutting the rear out to tube the bottom and get the link locations done. Since only the bumper and the shocks will me mounted in the back, it will be pretty minimal frame!

Final weight hopes/estimate? Looks like its coming along pretty bad ass.

It will just make the class weight limit which is 1910lbs. with fuel and driver

With ~450whp... Jesus. :O

yup 1900lbs and 450-500whp=unhappy porsche and LS1/LS7 owners on the track.

Adding some bars to the front from the cage to the strut towers. No need for strut tower bars after this!

I think it may have been you emailing me before, but did you ever find a turbo manifold?

Yes it was! Well I think I might end up building my own at this rate. I have all the parts, so might as well. It is an easy one since I have all the room in the world and the downpipe is crossing over the transmission to the other side. Unless you are thinking about doing it!

Found a 8.8" rear-end out of a 2003 crown vic police interceptor with only 15k on the car. It needs to be shortened but it will work great!

wow 1900 w/ 450 hp? This is fuggin nuts!

Yes, when you think about it it's going to be amazing. 450-500WHP, 13" brakes, 12" slicks, all in a 1900lbs car. The limitations will be the driver!

drooool.


so then will the axles be custom? or will you source some shorter ones from another car?

Yea seriously. THis is like grand-AM/World Challenge levels.

Well custom axles are easy to get. I might actually switch all 4 wheels to wide 5 hubs at this rate. I am 90% decided on it. I will have to look and see.

It will be fun! I am sure there will be stuff to play around and fix in the process of running that much power like other guys that run on track with turbos on here have found. It is all fun!

If you plan to use the cas shutter wheel from diy let me know and I will send you info on how I set mine up.

That is my plan. That would be great and save me time!