2G Intake differences/advantages?

I have two RX-7's, and the intake systems are different. Can anyone offer information on the merits of either? Which will work better in ITS on a G2?

After the throttle body,the '87 has visible 4 intake tubes from the top section curving downto the middle section of the intake assembly. The '89 has a "box" after the throttle body, and the four tubes are virtually vertical under it, very difficult to see, and curve to the second section. They appear to be almost in a straight line orientation, whereas the '87 are staggered with the middle two tubes not lined up with the end tubes.

Any thoughts for me? I'd very much appreciate the general knowledge.

Good racing. Bill

Just about everything from the 89+(S5) cars is prefered. Intake, AFM, shortblock, etc. All contribute to the higher stock power rating of the S5 v. S4 cars.



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Chris Ludwig
08 ITS RX7 CenDiv

[This message has been edited by C. Ludwig (edited October 26, 2003).]

Does anyone have any apples to apples dyno data on this?

I am running the S4 intake setup as well as the S4 MAF and wiring harness (car is an 87) but do have the right block and rotors, etc. ISC exhaust and header have me at 170 rwhp and 132 ft/lbs on the dyno.

Anybody speculate what hp gains/torque losses I will see when I switch to the S5 intake this winter? (I will be leaving the S4 MAF in place...)

AB

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

[This message has been edited by ITSRX7 (edited October 27, 2003).]

No hard numbers Andy, but it is my understanding the 89+ intake is worth @ 6-8 hp. Care to chime in Mr. May.


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Marc Dana
#63 ITS Mazda Rx-7
#77 STS BMW 325I

There was a dyno sheet floating around on RX7Club.com, god, probably 2 years ago, and it was an honest 8hp if I recall correctly.

PaulC

Great question. Any issues of mixing/matching here? I've got an '86 MAF and ECU, a "curvey" (89+ ?) intake, unknown short block (suspect pre-89), and high impedence injectors (with resistors bypassed).

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Marty Doane
ITS RX7 #13
CenDiv WMR

No real issues. Just make sure you have the internals from the 89-91 so you get the high compression/lighter rotors. You know, the 160hp version of the motor instead of the 146.

AB

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

Thanks for the intro Mr. Dana. You will see on average 8 HP by upgrading to the 89 and up configuration. Andy, what type of dyno have you gotten those numbers on?

Dynojet at ACS Raing in Hanover, MA.

www.acsracing.com

We have had a few dyno days there and our cars put up from 164rwhp to 171rwhp. (Nick's new SS motor hasn't been run)

I also remembered the numbers wrong (had to look at the dyno sheets). 170RWHP @ 7700RPM and 130ft/lb @ 6250. These numbers are with the ISC header and exhaust.

Baseline numbers with RB header and homemade 3" into Walker Dynomax were 165RWHP and 132ft/lbs.

Are you talking whp increases or crank numbers with the S5 intake?

AB

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

Sorry to snatch your topic Andy.
Hey Rob, can you imagine the Silver Bullit with those numbers. They all can't stand me now. Whew, in my dreams.
Andy, any inside jokes I can play on Nick at the ARRC? After he races, of course.:-)

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Marc Dana
#63 ITS Mazda Rx-7
#77 STS BMW 325I

And just to add - how about if I add the S5 AFM?

AB

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

Does any one know how to make the later style air flow meter work with an early wiring harness and computer? I know it can be done because I have seen 2 cars that run this setup, but there is no information on how to do it anywhere.

Quote:

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Originally posted by ITSRX7:
No real issues. Just make sure you have the internals from the 89-91 so you get the high compression/lighter rotors. You know, the 160hp version of the motor instead of the 146.

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How can you tell if a short block is 86-88 or 89-91?



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Marty Doane
ITS RX7 #13
CenDiv WMR

The hot setup seems to keep evolving. A few years ago, when I was running an all-S5 ('89) car, the concensus I was hearing was that the S4 ECU and AFM were superior to the S5 but the S5 intake and rotors were superior - so the hot setup was an early car w/ late engine. At the advice of one of the Fla. shops I went so far as to try to retrofit an early ECU and AFM into my '89 car. Then I found that the '89 body wiring harness has competely different plugs than the early ECU so I got out the wiring diagram, matched up all the individual wires, and spliced the '89 harness onto the an early plug. Very difficult. Long story short - it never worked worth a crap and I went back to all '89 but I had wiring w/ a jillion splices in it.

So, is it now established that all-S5 is the way to go?

Thanks for all the replies. I have a much better idea of where to go with this project. I'll be back!

Good racing.

Bill