2nd Gen. hybrids - what's the best way to go?

[bldn10]

Who is running what combinations of:
1. Chassis
2. Block
3. Intake
4. ECU
5. AFM

and, assuming you do, why do you think yours is the best setup?

S4 = 86-88 S5 = 89+

Bill Denton
Memphis

[theenico]

Bill,
There was an article in GRM back in '96 or '97 I believe that listed all the "bests" from each chassis/platform.
To summarize:
1. S4 base model (least options & lightest dash)
2. S5 *
3. S5 *
4. S5 *
5. S5 *
* (2.-5. also reguires the S5 engine wiring harness)
Of course the 5 lug brakes and 4 piston calipers are the ones to use as well as a 5.12 R&P.

Monica's #00 car, though, seems to be an anomaly. It's an '89 non-sunroof, manual window, big brake, and aluminum hood car. She did a Carfax on it and it comes back as a plain Jane RX-7, although to look at it you would swear it was one of the GTUs's that Mazda built for showroom stock.


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Nico
KCRaceware (816) 257-7305
[email protected]

[ITSRX7]

We have a weird parts car as well. 1989 Non-roof car with roll up windows and all the right suspension/brake/hub stuff...and it's a GXL.

Weird.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com

[bldn10]

Come on guys, what are you running? Andy, what are the FOM cars, particularly Nick's?

Nico, you say that the S4 chassis and S5 ECU are preferred but that does not compute. To put an S5 ECU in an S4 car you would have to change the body wiring harness plug (or the entire harness), and I can say from experience that that is a nightmare. Some of the individual wires don't even match up. Is this being done and how so? Otherwise, you are stuck w/ the S4 ECU. So, would an all-S5 not be better than an S4 w/ S4 ECU but S5 everything else?

[C. Ludwig]

Nico's hit the popular recipe. It's been gone over a couple times recently. You'll need the "front" and "emissions" harnesses. That's Mazda's FSM nomenclature for them anyway. Why be scared of changing the harnesses? You're stripping the car to noithing to properly build it anyway.

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Chris Ludwig
08 ITS RX7 CenDiv

[C. Ludwig]

Ooops. Double post.

[This message has been edited by C. Ludwig (edited November 16, 2003).]

[itaracer]

Bill,

I ran into Doug Ford at the convention. He told me you were coming back to ITS. Welcome back.

Nico,

I also talked to Charlie. Better crank up the welder. I'll need that Tri-link sometime next month.

[ITSRX7]

Sorry - didn't know you were looking for specifics from me!

Nick's car is an S4 - stripped to the BARE frame and built into a 99.9% S5 car (the taillights from the S5's are too valuable to run - if you have them, sell them on eBay for $200+ and get 4 sets of the S4's...so the .01% of Nick's that is S4 is the TL's.)

Start with an S5 if you can. You will not have a problem getting the car to minimum so the lightest starting package is irrelivant. You will get the better intake, the better AFM, the better front bumper and the better computer. You see most hyprids out there because the S4's are more common on the "blown motor, good chassis market".

My car is an S4 with S4 parts throughout except for the engine rotors and front bumper. I will be uprading to the S5 intake this season in the search for a few more hp but I will keep the S4 MAF because I don't want to screw with all the harness crap. I am not great with the electrical stuff. The car makes great power now so finding 1-2 more isn't worth the effort on that front for me at this time.

Feel free to contact me off-line for full details and tips.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com

[theenico]

I agree with ITSRX7. Just start with the S5. Due to an incident with a deer (back when it was a street car) Monica's S5 now has a steel hood. She also runs with about 90# of ballast and has to start each race with a full tank of gas. Basically, if you weigh 200# or less, getting down to minimum weight should not be an issue. The article/recipe I was using is supposedly what Speedsource does and I myself have not tried it. Good luck, and welcome back.

BTW, we make an attractive and very light front splitter that fits both styles of front bumper for $150 (shameless plug http://Forums.ImprovedTouring.com/it/smile.gif )
If want to see a picture, email me and I'll send you the pics.

------------------
Nico
KCRaceware (816) 257-7305
[email protected]

[This message has been edited by theenico (edited November 17, 2003).]

[This message has been edited by theenico (edited November 17, 2003).]

[bldn10]

Thanks, guys. Since I have to add ballast to make weight, there seems to be no reason for me to go w/ an S4. However, it looks like I will be buying my old car back and it is an S4 w/ S5 engine. Can an S5 AFM be spliced into an S4 engine wiring harness and run off the S4 ECU? Worth fooling w/? Any idea how much performance may be lost w/ S4 ECU? Chris, I suppose that the fast S4 cars had actually been stripped and converted. Changing the body wiring harness in situ would be a major hassle - do you think anyone has actually done that?

[ITSRX7]

There are plenty of S4's with S5 AFM's. It's just an electrical nightmare I don't want to undertake until I feel I need that 1-2 more HP. You can make real good power with the S5 internals and the right bolt on stuff. I saw a 5rwhp gain with the ISC stuff.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com

[Greg Amy]

<font face=\"Verdana, Arial\" size=\"2\">There are plenty of S4's with S5 AFM's.</font>

I'd suggest it's contrary to the rules to modify the S4 wiring harness to accept the S5 AFM. I'd also suggest that swapping over the S5 wiring harness into an S4 car to accomodate the S5 AFM is legal.

Semantics? Maybe, maybe not...

[bldn10]

"There are plenty of S4's with S5 AFM's. It's just an electrical nightmare I don't want to undertake until I feel I need that 1-2 more HP."

But are those S4 cars running the S4 ECU or, as Chris suggested, have they been completely converted to S5? It would not be a big deal to splice an S5 AFM plug onto the S4 wiring harness as long as it will work w/ the S4 ECU. I hope it is illegal because I'd just as soon not do it as long as no one else does either http://Forums.ImprovedTouring.com/it/smile.gif.

BTW I got out about the time mods were allowed to ECU's - did anyone find any real gains from it other than adjusting or removing the rev limiter?

Bill

[cmstrilchuk]

Andy,
'common wisdom' is that the S5 AFM is better, but has anyone verified that it makes more HP? Mazda made changes S4 to S5 in some cases just to save $$, like the one piece LCA's.
The wiring conversion from S4 harness to S5 meter is not too burdensome. I'll cross my fingers and hope this link works - here's the schematic:
http://www.rx7club.com/showthread.php?s=&threadid=146267&highlight=AFM+wiring



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Curtis
'86 RX-7

[cmstrilchuk]

try again......


http://www.rx7club.com/showthread.php?s=&t...ight=AFM+wiring (http://www.rx7club.com/showthread.php?s=&threadid=146267&highlight=AFM+wiring)

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Curtis
'86 RX-7

[ITSRX7]

Legalities aside, I have seen S4's with S5 MAF's and S4 computers.

From some of the more technical RX-7 guys I have talked with, all the S5 still is supposed to be better.

-computer (much 'faster' - more adjustments per second)
-MAF (better design and one would think better flow)
-Intake (see above)

Start with an S5 and take the confusion out.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com

[Eagle7]

Originally posted by ITSRX7:
... I saw a 5rwhp gain with the ISC stuff.
To which ISC stuff do you refer?



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Marty Doane
ITS RX7 #13
CenDiv WMR

[ITSRX7]

Originally posted by Eagle7:
b]
To which ISC stuff do you refer?
[/B][/QUOTE]

The header, expansion chamber and muffler set-up they sell for ITS RX-7's. I had a Racing Beat header into a custom 3" into the same muffler they sell (Ultra Flow)

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com

[Silkworm]

I'm running S5 block, S5 intake with S4 electronics, S4 AFM and S4 injectors.

No dyno results yet, but the other 2nd gens in my class all say I've definitely got the edge on them in power, and my car is the heaviest of the three (with me in it of course http://Forums.ImprovedTouring.com/it/wink.gif They're all S4 only though.

PaulC

[ITSRX7]

So they are using the 146hp engine and you have the 160hp setup. There is 10 RWHP right there. And if you believe the info on the S5 intake, add nother 4-5 for that.

AB

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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com

[Eagle7]

Originally posted by ITSRX7:
The header, expansion chamber and muffler set-up they sell for ITS RX-7's. I had a Racing Beat header into a custom 3" into the same muffler they sell (Ultra Flow)

AB

Very interesting. Do you know:
1) Does the header contribute significantly to the improvement? and
2) Is the expansion chamber compatible with the RB header?

Do you have (or have seen) comparitive dyno runs? Curious about how the torque curve changes. I'd expect the expansion chamber to be tuned to an RPM band, like you get with two-stroke bikes - different pipe for low or high end.

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Marty Doane
ITS RX7 #13
CenDiv WMR

[Eagle7]

Originally posted by ITSRX7:
So they are using the 146hp engine and you have the 160hp setup. There is 10 RWHP right there. And if you believe the info on the S5 intake, add nother 4-5 for that.

AB

Isn't the S5 intake already part of the 160 hp setup?

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Marty Doane
ITS RX7 #13
CenDiv WMR

[Eagle7]

Originally posted by theenico:
...as well as a 5.12 R&P.

How would you compare a 5.12 vs a 4.88 vs a 4.10? Not an insignificant cost difference to go from 4.88 to 5.12. Big difference? Depends on the track? Not as good for some tracks?

Thanks,

------------------
Marty Doane
ITS RX7 #13
CenDiv WMR

[carlos e gutierrez]

Originally posted by Eagle7:
[quote]Originally posted by theenico:
[b]...as well as a 5.12 R&P.

How would you compare a 5.12 vs a 4.88 vs a 4.10? Not an insignificant cost difference to go from 4.88 to 5.12. Big difference? Depends on the track? Not as good for some tracks?


Marty:

The 4.10 is useless. You are giving up a ton in acceleration in each gear. Think "low E.T." in the 10 or so drag races you do each lap (from corner apex to braking point of each turn). Remember, the 4.10 slows you down in all the gears.
4.88 vs 5.13.
If you are spending $ to buy a new gear, go for the 5.13. Either one you choose will also require you to rebuild your tranny with the GTU-S 5th gear, as you will now use 5th gear at almost every track you go to. If you were using the 4.10, the improvement with a 5.13 and the GTU-S 5th is easily 2 seconds per lap at any track.
Down here in the SEDIV, everyone runs the 5.13, at all the tracks including Daytona.

P.S. What drivetrain components do you run?
Motor? S-4 or S-5 ?

[Eagle7]

Originally posted by carlos e gutierrez:
P.S. What drivetrain components do you run?
Motor? S-4 or S-5 ?
I got the car last winter. It claimed to come with a '90 engine (not yet confirmed) that turned out to have bad apex seals. I put an S4 engine in and used the S5 intake. The original engine gets rebuilt this winter. Do you know how I can confirm whether the original block is an S5?
I've got several transmissions, including at least one of each ratio, but I've not yet gotten into 5th, so which one to run hasn't mattered.
Car came with a 4.10 welded diff, which burned up at my first school (don't ask). I replaced it with a junkyard 4.10 LSD that slips.

Thanks,


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Marty Doane
ITS RX7 #13
CenDiv WMR

[Eagle7]

Originally posted by carlos e gutierrez:
Down here in the SEDIV, everyone runs the 5.13, at all the tracks including Daytona.

How about clutch LSD vs Torsen? Primarily a maintenance issue or a real performance difference?

Thanks,

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Marty Doane
ITS RX7 #13
CenDiv WMR

[C. Ludwig]

To tell the difference of the "block" look for the EGR valve. S4s have them on the top of the center housing. S5s have a machined flat where the valve used to be. The important thing is the rotors. The S5 rotors have the combustion dimples machined in the rotor with a fairly smooth surface. The S4 rotors have a cast combustion dimple.

After driving both Torsen and clutch type cars I like the Torsen. The only problem is that Torsens will still unload if a wheel comes off the ground. May be a problem heading in to the bowl at Grattan? That's the only place I've been that I can really see a problem.

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Chris Ludwig
08 ITS RX7 CenDiv

[Eagle7]

Originally posted by C. Ludwig:
To tell the difference of the "block" look for the EGR valve. S4s have them on the top of the center housing. S5s have a machined flat where the valve used to be.

S4 it is - bummer. I've got a full set of new S5 housings, and see the difference you described. All 3 of my engines are S4.

<font face=\"Verdana, Arial\" size=\"2\">The important thing is the rotors. The S5 rotors have the combustion dimples machined in the rotor with a fairly smooth surface. The S4 rotors have a cast combustion dimple.</font>
Anyone know where I can pick up a couple S5 rotors?

<font face=\"Verdana, Arial\" size=\"2\">After driving both Torsen and clutch type cars I like the Torsen. The only problem is that Torsens will still unload if a wheel comes off the ground. May be a problem heading in to the bowl at Grattan? That's the only place I've been that I can really see a problem. </font>
Yeah, I've been smoking the right rear through that corner. I also hear a little RPM blip cresting the rise on the long sweeper after the bowl.

Thanks,

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Marty Doane
ITS RX7 #13
CenDiv WMR

[C. Ludwig]

On my old cheapo Koni shocks I used to unload the right rear going into the bowl very badly. Pick the tire up, let off the gas, wait for it to set down, back on the gas. BAD! With no other changes and the new custom Bilsteins the problem was not quite totally eliminated. To the point you could stay on the gas atleast. I've never had a problem exiting the bowl on that next rise.

That is with a old, blown stock LSD. Haven't driven with a Torsen at Grattan.

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Chris Ludwig
08 ITS RX7 CenDiv