Tinman's 3.8 V6 NASA PTD road racing GTUs

[Tinman]

I've been wanting to do a build thread for some time, since the other forum was our place to escape the rotary nazis. since then my GM 3.8/T5 FC has morphed from daily driver to track day whore to all out wheel to wheel race car (still street legal...ish)

From this


To this


To this




A little background. When I was building my SB2 FC a friend of a friend asked if I wanted another FC to play with. I wasn't too interested but checked it out anyways. What I found was an 89 GTUs with around 140.000 on the clock. The motor was toast, the interior was mostly stripped and the taillights were missing. There was a major dent in the driverside front fender and a crease in the rear fender right above the wheel on the same side. On the plus side it was rust free and it was a GTUs! I handed over $400 and drug it home.

I'm not sure how long it camped out in my driveway before I started on it. I had a nice daily driver, the SB2 FC for a project, and even a beater F150 to haul dirty bits in. The GTUs just did not have a place in my fleet yet. Then I got to thinking, if I sold my daily driver I would have more cash to throw at the SB2 car. the daily was FWD and an automatic, two more reasons to get rid of it. Time for a plan.

The GTUs shall become my daily driver. The search is on for a drivetrain, another rotary just won't do. They are neat little powerplants, just not my taste. I needed something cheap, fuel efficient, and at least as powerful as the rotary it would replace. My initial thought was 5.0/T5 from a fox body or SN95 Mustang. I found a few but none at the budget price I wanted to stay at. So I broadened my search and hit Ebay again for the 20th or so time. What I came across was something that didn't excite me much but fit the bill fairly well, a 3.8 liter V6 and T5 transmission out of a 98 Camaro complete with ECU and harness, the price, $600. Fuck it, I'm tired of searching so I bid $650 and went back to work on the other car. Three days later and damn!, I was the only bidder, I guess I'm the proud owner of a V6 I know nothing about. Time for some research.

Turns out GM had their stuff together on this little bastard. It's a little heavy due to being all cast iron and the heads don't flow well but it's rock solid reliable and gets great mileage. Plus it's power numbers are not far from the 5.0/T5 I was originally looking for. Time to get transplanting.

[largeorangefont]

Awesome!!

Any details on the race car would be appreciated as well. What front airdam setup is that on it? DIY or a product someone sells?

[theantirotor]

are those side pipes or side skirts i am seeing on there?

[Tinman]

The airdam is home built. I have plenty of photos of it I will be posting in this thread soon.

Sidepipes, no shit. NASA's Performance Touring rules are great for folks like myselt that aren't afraid to try things. The sidepipes are my way of getting an aero advantage working in the gray area of said rules.

[theantirotor]

lol awesome.  def. interested in more pics!

[Tinman]

I don't have any good pics of the pipes but will get some in the near future. I don't know if I would recommend them to anyone else, this is kind of an odd situation that they seem to work well in but they're probably way out of place for any other RX7 swapped or not.

[digitalsolo]

Hah, this is a cool build.   I always like the 3.8 motors, beefy suckers.

[Tinman]

A few shots of the 3.8 going in for the first time.







And the simple yet effective mounts.



The engine nests tight to the firewall and behind the steering rack. The block itself is slightly behind the front axle. To make it happen I had to use a fuel rail from a FWD 3800 as it loops over the intake manifold instead of behind it like the Fbody rail. I wanted to go cheap and use the F body exhaust manifolds but they would not fit between the framerails so a pair of Pacesetter headers was purchased. The passenger side fit fine with a little massaging of the firewall. The driverside had to be completely reworked.

Installed and running

[Tinman]

First track day with NASA, HPDE 1 in the rain at MidOhio



Heading home from a track day at Putnam Park



After one of her few baths over the years. Also sporting the first sheet aluminum front lip I made, lasted less than two months.

[stormdrop]

sweentess is what this is.

[cool]

Cool build!  More pics please of both hotrods.

[Cman]

I have some friends with a brand new PTD (or is it E ?) FC with rotary power. What kind of power do you make ? You must have had to produce dyno graphs and weight to get classed ? The loophole in NASA classing is classing by max power instead of torque.  The Corvette guys play this game with big displacement engines and truck cams...sometimes with restrictors.

Steve

[Tinman]

Thanks for the compliments so far.

Cool, I'll be posting many more pics as I add to the thread. Next will be the rollcage, then the airdam/undertray. Let me know if there is anything specific you want to see and I'll see what I can do.

Cman, The 3.8 takes advantage of the dynoclass PT loophole very well. I was issued both a max RWHP and RWTQ along with a minimum weight, 186hp and 230ft.lb. at 2850lbs. Currently it makes 184hp and 225ft.lb., I had to pull a lot of timing to get it down from the 200rwhp it made. On the downside I was issued the same hp/weight ratio as a supercharged Miata in my class, his superior suspension trumps my torque advantage IMO.

[Tinman]

Time for the race car part of the build.

Stripped down to next to nothing, seam welded, and the rollcage starting to take shape. At this point the only bolts in the car are for the fuel tank straps and door strikes.



Mainhoop rear brace plates. A little on the large side but within the limit of the rules. I wanted to not only tie in the rear shock mounts but also extend down to the "frame".



More bars going in. I later changed the A pillar bar supports, I felt they were to intrusive to the interior and too close to my left hand when it was on the wheel. The tube extending down from the lowest doorbar is just a jacking point and is not welded to the floor.



A few more bars and the new A pillar bar supports.



NASA modified the PT rules in 2010 to allow the two more attaching points at the firewall, I was glad to take advantage of it as I think these bars a crucial.



Taco gussets.



After paint, original Mazda color as the rotary heritage is so important to me 

[93silverbullet]

Great build! Love the transition from daily driver to track terror.