A few months ago we where going to take our RX7 to the $2005 Challenge....this car was built specifically for this purpose and had a helluva lot of work put into it. Well, I tried for several days to get the car to start, with no luck. I checked every sensor and every connector, traced everything back and still couldn't figure out why the damn car wouldn't start.

Well, fast forward 2 months. Last night I was working on the car, trying to figure out why the stock computer STILL wouldn't run the car, and then it hit me. When I started working on the car, I had to make new fuel lines almost everywhere. One of those fuel lines connects the primary and secondary fuel rails. The person who made the line (most likely me....but we did have 8 people working on the car) made it a little too long. There was a kink in the line, and I assumed that the pressure of the fuel would force the fuel thru the hose.

Don't ever assume anything.

It turns out, that fuel line was acting as a kind of fuel pressure regulator...it was blocking the flow of fuel to the secondaries, and not allowing the fuel to return to the tank. Well, that also resulted in a very very high fuel pressure on the primary rail, resulting in a severe flood every time I tried to start the car. Fixed that problem, and a few cleanings of the spark plugs and BAM, car fired right up!

It still floods...but I suspect I have some adjustments to make...plus I found I have a small water leak behind the turbocharger, and the oil press and water temp gauges don't work right now....I'm going to fix all that tonight, hopefully. I also need to install a switch to turn off the fuel injectors...but I really hate to do all that work, because I'm installing a Megasquirt as soon as the engine is broken in.

 

Well the good news is that now you have months of testing/tuning available to you before the next competition.
So start practicing your drag launches and honing your autocross sk1llz.
Any pics?

 

So, will it make an appearance at the $2006 GRM Challenge? That extra $1 could go a long way!

Sorry I couldn't make it to Gainesville this year, but when you guys weren't going to bring the RX-7, I decided it best to stay home and finish some other things.

Good to hear it's running now.

 

We have a nice breakdown here:
http://www.n1xrr.com/2005challenge

 

Trust me in saying we where all a little disppointed. We did end up taking our CRX and placing fairly well...most challenge vets didn't place as high as we did!


This car is going to be going thru some extensive testing...
And the car will be Megasquirted withen 2 months....spark and fuel.

Once I fix the water leak, the oil press and water temp gauges, I'll be taking a video...and I'll post it up here for sure!

 

that is cool

 

I'm just really glad you are sticking with rotary power. Way too many people are sticking v8s into the rexes for the GRM challenge. I really liek that magazine btw...

So tell me, why did you chose turbo over n/a? Seems like you can get almost as much power cheaply with a bridgeport for very little money, and save a couple of hundred pounds with the lighter drivetrain.

 

I wouldn't quite say a couple hundred....maybe 50-60lbs.

The main reason is the power band. We need power from 3500-6000rpms, not 5000-9000rpms....unless we get a 5.12 or higher gear, which will cost a good bit more money.

Your right though, too much V8 crap at the challenge....there wasn't a single rotary powered vehicle at this years event....despite the 3 RX7's that where there.

 

The V8 FC pretty much dominated the competition, v8 crap ehhh?

Good luck to you.

Can't wait to move so I can start my subscription to GRM.

 

Hehe, I knew I'd get a rise out of someone.

I have a lot of respect for guys who put V8's in RX7's....especially if they did it without a kit. Its a lot of work, time and money to do an engine swap and its not to be taken lightly, but I for one don't want to put a V8 in an RX7. Too much extra weight.

 

hey, why would you say the Turbo only weighs 50-60 lbs more. The cars instock trim are definitely over 200lbs right? And a lot of that has to do with the beefier tranny, drive train, tyurbo and its engine accesories. Not saying you're wrong or I'm right, just want to hear your opinion.

 

Their GRM Challenge car isn't stock. The only added weight for a turbo drivtrain over an N/A drivetrain is exactly that - differences in the weight of the drivetrain. It's a race car, there is no interior, no PS, no ABS, etc. That's where some of the difference in N/A vs. TII weight comes from when you're comparing stock cars.

So, I'd guess he's in the ballpark when mentioning 50-60 lbs.

 

Thats exactly true.

Let me quote a few stock weights here:
1986 Base model: 2625 lbs
1988 Turbo II: 2945 lbs

Where does that weight come from? Well, I've got to tell you its not just the engine transmission and differential. The turbo's came with every option almost every time. Sunroof, electric windows, power steering, etc etc. The wheels alone weighed a good 6-10lbs more each.

What did we remove? Short answer: everything. The doors are gutted and the structure removed (no more bracing), we lost 1/2 the weight of an empty door right there, then add glass and the door panel. There is literaly nothing under the dashboard, no heater or A/C, no logicon, nothing. Wiring still remains, but the majority of that will be removed.

Turbo vs NA...its all in the accessories. I've yet to weigh this car, but with the Lexan rear hatch, all the cutting and drilling we did....I'd say we're damn close to 2200lbs....maybe 2250, we'll have to see about that.

We started with an '86/'87 base model...no sunroof and manual steering. The lightest of the light. Then we removed the 100+lb exhaust and replaced it with about 25lbs. Removed the A/C, that was a good 30+ lbs. The doors where 25+lbs each. Interior worth a good bit overall, plus no passenger seat. Most of the dash is no longer there, the rear glass is 2/3 of the weigh of the hatch....Lexan is MUCH lighter.

You can see we're getting close to 2300 EASILY. I've yet to weigh half this crap....mostly because we don't have a decent scale. Don't forget all the nuts and bolts we removed....they add up. The whole storage bin setup weighs a decent amount. We're going to get rid of the stock wiring and run Megasquirt with a 12lb battery (vs 25+lbs). Right there is a good 15lbs worth of wiring.

We also have something the base model didn't have: an aluminum hood. Thats good for at LEAST 10lbs....I'd say more like 20, but lets not get too greedy. I've got a digital scale I'm picking up from work in the next few days, I'm going to start weighing all this crap.

 

i cant wait to see that car done!!

 

awesome to see someone else putting a 7 on a diet. My 87 turbo is currently going on a diet. Where do i find info on the grm challenge?

Jesse

 

And here's the video!

http://www.n1xrr.com/itsalive.MOV

More info on the challenge can be found here:
http://www.grassrootsmotorsports.com...005-challenge/

They don't have next years info up yet....they normally get it up twords the end of the year.

 

that awsome, have you driven it yet?

PS-this is masin

 

Hows it going Masin? Did you get the rotors out of that engine yet?

We haven't driven it yet. I've got to pull the turbocharger off of the engine to fix a water leak, and then trace back a problem with the gauge cluster so I can at least see if the water temp and oil pressure are semi-correct. Then it'll have a nice break in...and finally the car will be taken down for a month or so for me to get the car running on the Megasquirt. Its so close I can taste it!

 

If I can chime in: with everything you've removed, there's no way in hell its going to take you a month to get your megasquirt setup in there Hell, you're only going to have 5 or 6 wires (plus your injectors) going into the engine bay.. you'll probably get it wired in one day Its super-easy to get these cars at least idling with a megasquirt, and not too hard to tune after that

 

well i may not be taking my 7 to those types of competition- but i'll be representing rotary power with my triumph . rotaries may not have much torque but a 1800 pound car doesn't need much torque to get it going. unfortunately the triumph won't be there until 07 at the very earliest. i'm doing a complete restoration and it's got a lot of rust that needs to be taken care of before anything else can even be considered. unfortunately 2k is prolly how much i'm gonna be dropping into just the engine, so i think i'm going to be doing the ultimate streetcar challenge.