Jump to content
HybridZ

My Buddy's GN-Powered 2nd-Gen RX-7


Scottie-GNZ

Recommended Posts

As some of you know, I helped a buddy build a GN-powered 2nd-gen RX-7 and we have been testing to make sure all is OK with the swap using a stock drivetrain he pulled out of a used car he bought. This engine is in the car until a more "powerful" engine is put together. The car has the stock turbo, but a massive FMIC, upgraded pump (Walbro :D ..), 50# injs, 3" DP and a single 3" pipe into 2 2.5" with Ultraflows. This car is so quiet, you can barely hear it from 60' away when he is doing a burnout!!

 

This past Wed night some serious tuning was done and after Mike Kelly and Jeff left, the car ripped off 12.33 @ 118 with a lousy 1.99 60'. It does not have a line-loc and he gets the brakes too hot trying to heat up the tires then they do not hold at the line trying to build boost. What is so amazing is that the car has a 4.11 and probably weighs in at 3100+ with driver and about 50+lbs of tools and stuff in the trunk. That translates to 390rwhp and we were not even looking to come close. We are now obsessed with getting a 1.70 60' and getting an 11.99 before pulling out this stock drivetrain.

 

The ULTIMATE SLEEPER and the other engine will have at least another 130hp! and be no louder or less driveable.

 

Sorry, I know it is not a Z but just thought I would share it. BTW, Tim, this is the drivetrain you were interested in buying.

Link to comment
Share on other sites

His website for the RX-7 is www.misred.com

 

It has a gazillion pics but not currently labeled so you just have to go through them all. Tedious and a lot related to the GN drivetrain but worth it for someone doing a V-8 FC. He is running the stock GXL IRS and is waiting for Grannys to finish a 3.27 R&P they have been promising for a while. He also has a C4 diff and one of these days we will seriously look at how we can fit that in the FC IRS.

Link to comment
Share on other sites

Guest Anonymous

Hello Scottie and company!

 

Scottie, thanks for the free press! The motor that is currently in the MisRed car originally came out of a parts car. It was a Buick GN with about 144k miles on it. Being very familiar with the Buick drivetrain, I can almost guarantee the motor had never been out of this car since it had some rare brackets and wire ties that you usually don't see hooked back up once someone r&r's the motor. I am very pleased with the cars 118mph number from the other night at the track. I figured a fairly healthy stock motor would get me around 114mph but I had no idea it would go 118mph. On the last run of the night, the car picked up 27MPH in the last 1/8th mile.. something unheard of for the Buick and is a direct result of the Mazdas slippery aerodynamics and weight (2960#). Looking back at my runs from the data logger, if I manually shift the 2-3 and the 3-4, I believe it will actually go a little quicker. Need to let it wind out to 5500rpm in all gears.

 

There are some issues with the motor, like a cracked header and unknown valve springs that could also be addresses for more horsepower. I am in the process of building a 4.1 liter Buick GN motor that should easily make about 125hp more then the current setup. Of course the car isn't anywhere being finished as it needs a cage, paint, A/C hooked up ect.. Another major project will be addressing the rear end gear. Right now it's 4.11's and is horribly mismatched for the GN drivetrain. These motors make gobs of torque and prefer to be loaded up. An ideal gear would be 3.07's or 3.23's.. Problem is, there aren't any taller aftermarket gears for these unique rear ends. 3.90's came in the automatic RX-7's, but would be a waste of time to go through the trouble of converting to one of those since the difference would be only about 5% change.

 

It's no Z-car, but it's a hybrid and a sleeper at that. It's amazing how I can not find a street race in my Buick to save my life.. but roll around in the Mazda and everyone 'tries' you. So much fun!

 

Also want to say thanks to Scottie for his master fabrication skills and ideas that he came up with in the whole process of building this car. Couldn't have done it without him! Thanks again!

Link to comment
Share on other sites

Can you tell us more about the battery you're using? It looks like a unique shape but without being able to expand any of the small pics I cannot tell :( More detail on that puppy please as it might be applicable to several projects. smile.gif How much does it weigh, must it be vented, etc. etc.

 

All in all a SWEET swap! No one suspects much of the older RX7. An FD3 is sexier IMO but way more expensive. How does the older RX7 handle? You didn't get to drive it with the rotary,do you think handling changed much? Steering effected with the moved rack? Coool project! 2thumbs.gif

 

Read through the grief with the 4.1 motor, bummer! Hate crap like that :(

Link to comment
Share on other sites

Just got back from St. Augustine and I can tell you guys that this car was the ultimate sleeper... So quiet You could barely tell it was running... Scottie that is AMAZING! Huge improvement!

 

Good meeting you and your wife, and then hooking up with Jeff at the track!

 

Mike :D

Link to comment
Share on other sites

Guest Anonymous
Can you tell us more about the battery you're using? It looks like a unique shape but without being able to expand any of the small pics I cannot tell More detail on that puppy please as it might be applicable to several projects. How much does it weigh, must it be vented, etc. etc.
The battery is from Batteries Plus and is model 3ET. It's 525/460CCA and is a regular maintenance battery (ie, not completely sealed up). It weighs 57lbs. Luckily for me, it's over the back bumper.

 

How does the older RX7 handle? You didn't get to drive it with the rotary,do you think handling changed much? Steering effected with the moved rack? Coool project!
Right now the front swap bar is not installed b/c the newly relocated ps rack is in the way. The car handles like a dream if you ask me, so I really don't see a need to reinstall the front swap bar. As for noting a change in steering or handling before and after the swap, I couldn't tell ya. I have never driven a stock RX-7 and I bought this car with no drivetrain.

 

So far I am very pleased with the handling and performance of the car. There is only room for improvement from this point on, considering the car has stock shocks, springs, wheels ect.. smile.gif

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...