An End-of-build Retrospective on my Rx7 Evo GT by gmonsen

8-23-2013

Okay... Test run at Mid-Ohio on initial street tune. Motor has a few days heat cycling. Rpm was held to 6500 with one or 2 times hitting 7500 for a few seconds. Actuator for secondary exhaust pipe not working, so some exhaust restriction at higher rpms.

Gordon

Finally, Logan said that when the car breaks away, all 4 wheels break away at the same time. So, my weight distribution of about 48F/52R and my tires resulted in very neutral handling. The addition of the exhaust in the bumper and the huge subwoofer enclosure (70 pounds) adds weight to the rear. The lighter weight of the basic NA 3 rotor versus OEM stock, having deleted the power steering, and having the lighter billet aluminum Atomic Rex rack, lowers the front end weight from stock. So, pretty good shift of balance toward the rear.

Gordon

Here are a couple of pictures of the car when I got it back. 

Gordon

I love the exhaust. We haven't had a heat issue with the muffler box inside the bumper, which is fully enclosed in Incolnel, but there was some deforming of the plastic bumper skin where the stainless trim tubes got heat transferred from the tips, because there's less than a quarter inch between the two cylinders in some places. So, we've had to use a 4 inch diameter opening instead of the 3.5 around the tips and I may lengthen the tips themselves an inch or so.

The functional dual pipe exhaust (from collector to bumper) is working exactly as planned. Up to 3500 rpm the exhaust coming out of the collector goes through a 2.5 inch diameter pipe with a muffler in it and at 3500 rpm a butterfly valve opens the second pipe which has no muffler other than the exhaust muffler box in the bumper. When you go below 3500, the second pipe closes. 

Thanks, again, for the comment, David. This basically worked out as I'd hoped. (You know, one out of a hundred.  )

Jacob... I am rethinking whether the tips should extend a bit. Was trying to downplay them a bit, but might have them stick out an inch. The exhaust setup copies the 360 Modena's exhaust. (I copied the butterflies in the secondary intake ports from my LT5 motor.)

I noted a few things in my thread about the video we did of the car at Mid Ohio that I haven't noted here and just want to add them. The main thing is certainly what a dual purpose motor this is. It is absolutely factory-like in its low speed, idle, and cruising characteristics. When you get on it, the motor is still factory-like, but the secondary butterflies open and you have a different engine note and more power by half. The sounds are very precise, so you sort of hear how well its running. 

Its now been heat cycled, broken in on a track, and been driven on public roads for a few hundred miles. No leaks, drips, or drops. Oil temps have run 180-185. Didn't overheat at all in bad Philly traffic. Has started every time on the first crank.

A few more random pictures. Still 2 weeks from finally getting it back. Sometimes it seems like everything that can go wrong does. We were supposed to dyno the car last Saturday and the dyno owner has a motorcycle accident Friday night... Can't get on any dyno till next Tuesday. 

Gordon

I'm enjoying the car. Kyle from Speed1 was over today and took a couple of short videos. Its a bit loud now, but it was too quiet before. Seems I have a Goldilocks dilemma. 

Gordon

(I never do the videos right, but this should work clicking on the video.)

http://s234.photobucket.com/user/gmonsen/media/Mazda%20Rx7/Rx7%2007-20-14/MVI_2107_zpsc95872ed.mp4.html

And here's the other one.

http://s234.photobucket.com/user/gmonsen/media/Mazda%20Rx7/Rx7%2007-20-14/MVI_2108_zpse765cc09.mp4.html

The engine bay looks the same, minus the 3 plugs cosmetically. I put some filters over the ITB's. 

Gordon

David... Not sure who he got them from, but those Brit-style intake runners reposition the third ITB further away than it is with my more traditional manifold. Because my back two ITBs are so close, I can't fit those kinds of air cleaners. Also, I would love to hear from Simon how the runners work. I had thought they were pretty much for turbo cars.

Fritz... Yippee.

t-von... Thanks.

And so, here's a few more pictures of my dual exhaust setup.

Gordon

So, no videos and still no dyno. Logan says I make a little less than Lenny will. 

Some updates...

The oil metering pump (from a 1988 TII) leaked oil and it got worse over time to where it would drain maybe half my reservoir in a few days. Thanks to Ray Crowe I got a new one installed and all is well.

Although everything's running nicely otherwise, I'm thinking of going to a more sophisticated EMS. Like others, I went to the Microtech, because of its support for the 20b. Its a simple system and lots of people know it. However, it just doesn't offer so many of the features found on most of the better EMS today and I've always wanted my conversion to run in as "factory-refined" a way as possible. So, I'll probably take a look at the M48 and Adaptronic and whatever to see what to try next.

I have been using a full set of Spirit R brakes all round that I bought new from the factory. I had -- and still have "I think" -- that purist concept and wanted to keep everything Mazda. Last summer I bought a set of Mov'It brakes (6 Piston Fronts on 13 Inch Porsche rotors and 4 piston on the back and I forget how big the rear rotors are) about a year ago and am thinking of at least trying them out. Its kind of going from one end to the other, I suppose. 

I have been working on the dual bumper exhaust still trying to get that settled. Figured out a way to keep the outer ring of the trim tubes completely flush with the plastic bumper surface. We're putting a 3/4 inch stainless hose clamp around each exhaust tip holding 3 or 4 small aluminum "L" brackets flush and tight up against the inside surface of the bumper. The plastic bumper skin will be sandwiched tight between these new L-brackets inside and the stainless trim tube rings outside. Thanks, Kyle. 

I'll probably think about a little more or different mufflers. Got some time to decide in the Spring. (Naturally, after first getting the car I had told Logan I wanted it louder and when he made it louder I naturally think it may now be TOO loud.) 

Still has the original paint and the rear deck still has the various holes from the original R1 spoiler and the whale tail spoiler I had on it for a while plugged with those black rubber things. Looks like I sort of replaced "divits" in the deck... Last issues whenever they are issues.

Spending the winter trying to get the cosmetics back to where they were before an army of friends and mechanics worked on it for a few years. Which is kind of like trying to get me back -- cosmetically or otherwise -- to where I was 25 years ago. Bought a lot more buffing equipment for my bikes and am using it more and more on the FD.

Only another month or so to Spring!

The only EMS I have had a lot of experience with are the original EFI piggyback, the Haltech e6, and , while I have looked at the Microtech maps, I have never played with any of Logan's tunes at all. He is of course very very good. The best on 20b NA motors, imho. I've just wanted to leave everything alone. But I don't think I will be able to be happy with the Microtech. I mean, it works fine. Just not as refined as it would be with a modern Haltech or Motec. I'm not going to get worked up picking one or the other. If you were to choose between the 2 which would you recommend? 

G

Engine bay after some clean up.

Here are the current wheels and brakes and below are the front Mov'it caliper and rotor. They are kind of massive. I wonder if I'll need a balance valve to tune the fronts versus the new bigger 4 piston rears. They're supposed to work together, but we'll see. 

g

These are with the Spirit R's.

And here are the Mov'it caliper and rotor.

I suspect its down to the Motec or Haltech. This car's never going to be a 4 rotor, so... But a 4 rotor in the FF GTM interests me.

Here are a few shots of the exhaust, which is looking a lot better than its first iteration. I have polished the raw stainless tips -- which also now extend out a bit from the trim rings -- a lot. Wish that had been done before welding things up, but I have never gotten anything right the first (or second or) time. 

G

Heres a pretty good overall picture of how they look.

Heres another view.

Another.

And a close-up of the tip.

Other side.

September is good for me. Also, I used to do a meet in September and maybe we can make this into a combination track day and meet-and-eat?

G

Here are a bunch more exhaust and rear valance shots. 

Yeah. I might look into a trailer and upgrade ye olde pickup. I don't think oil prices are likely to drop further and the world situation suggest prices have underlying volatility.

But, if we do VIR in September, you have to be there. 

G

I've been trying to get the lighting right to show the way the back end looks with the exhaust and the aluminum lower valance. I know a lot of people look at the pictures like eye candy. Same way I do. I really love the way the back end came out. Looks pretty factory to me. 

duck91... Here's pictures of the bikes. Love the faux alligator pattern on the Guzzi seat.

G

So, I'm cleaning up my engine bay for the 800th time. I need to reroute my air con hard lines down. I was taking some pictures and noticed that I still have the black plastic radiator fans. I've got to find some nice aluminum fans to replace those. Maybe anodized or painted black? And I can still straighten out a few wires and hose runs over the next month. 

G

I do have a radiator shroud up top that really hides the fans and radiator pretty well from the front and a bit from the sides. Its shaped to mimic the curve of the front hood closing, so it doesn't cover quite as much as yours.. 

I have thought about it and its one of the reasons for not going with the three ITB's having the gap between the 1st 2 rotors rather than the three twisted runners that are evenly spaced, if you've seen that. I think one of the Florida guys building a 3 rotor NA has that setup. There is room for a strut bar, but I'll have to make one, because the throttles are located pretty high between the ITB's. I have thought about it a lot over time, but its never been at the top of my list. I will add one along with a tranny brace this spring.

I've also been working on my first year ZR1. I'm still doing basics, like adding the Corsa exhaust, a new ZF 6 speed, swapping interior from red to black and white, new wheels. Next step this year is upping the power a bit and my biggest improvement will be switching to coilovers from leaf springs. The leaf springs create a funny disconnect between the body and the wheels imho. Its been my daily driver (as much as I drive daily these days) and is generally more like a small cadillac than a sports car just going to the store. These are still pretty fast 12 second 175 mph cars stock and get a bunch faster with any mods.

G

Thank you. The 850 -- at least in 6 speed form -- is an undervalued and under-appreciated car. It is comfortable and fast and I've never had any issues with it. It was said to have electrical issues for example and I've never had any. Everything still works fine after about 80,000 miles. They are essentially worthless on the market, so I have just kept it. I have thought about trading it on a used Aston Vantage and may still do that. But I've had the 850 for almost 15 years and its hard to part with it. I'm running out of space though. 

The M3 has become so valuable that I can't DD it. The ZR1 is a reasonable DD in many ways, as I said, but I think the 1st year ZR1's are likely to become the most valuable of the Vettes since the C2's. Like the FD, you can have as much power as you want. You can get the motor upgraded to 450 whp for about $15,000 or so.

I'll take a look at them. It will have to go through the space between the 1st 2 ITB's, I am pretty sure. The key is that most of the bars are offset to the front or rear of the coil over top nut. I ran a string between the 2 coil overs and I can definitely fit one between them as far as the width goes. The way they shows them in ads, they never give you a straight down view of the bar, so I can see whether its centered or not. It kni=ind of looks like a few of the Cusco bars, like the 40 and ALC OS seem to be centered rather than offset, but I can't tell for sure. I'll take a look at the improved racing stuff. Thanks, Lenny.

I've been extremely busy at work, but have had time some nights and weekends to play. Its really nice. I want to explain what's different, but its hard. There's just so much torque everywhere. When you shift from first to second at anything over maybe 6500, it loses traction and the torque really slams you back into the seat. I'm running a 3.90 rear gear, but may go back to a 4.44 for fun. 

I took a deep corn Nardi steering wheel and painted the spokes cream to match my wheels, housings, and headliner. I'm using a custom made old school Mazda horn button that matches my interior a bit better.

G 

My friend Kyle from Speed1 was over and took a quick video of the car warming up. I know it sounds a bit like a bridge port, but its just a big street port combined with scalloped rotors giving a big overlap that sounds like a bridgeport. I like the low idle, so it'll stay rumpty-rumpty. 

http://s234.photobucket.com/user/gmonsen/media/Mazda%20Rx7/IMG_2037_zpsdctxtvdg.mp4.html

Not much. A 5 minute drive around my roads.

G 

G