DIFF I know a fix

[SG & NA Fisk]

The Dec USA Miata mag has an article on 302 (5L) V8 supercharged Mx5s you can
order. Interesting they reckon its faster than a hot dodge viper and claim 400
hp and 12.6 sec quarter miles - would be interested if U have yours dinoed?
They used RX7 diff & axles but had to replace with a "mustang diff" - my guess
this would be the proverbial 9 inch which all the drag cars run. The beauty
of these is U can get whatever gearing U need for them. You can also get axles
made to any length and can locate the housing via 4 bars & coils - suggest U
try any of the reputable HotRod engineers who have built drag cars in your
area. The 9 inch isn't cheap and its heavy, but it is the very best & I know
how annoying it gets replacing a diff every weekend.
Stevan

[shaznandy lockyer]

I believe it was the TORQUE of those s/c V8's that blew the RX7 diff and a blown four is not gonna need a nine incher to get off the mark!UNLESS, of course you're just gonna dump the clutch ALL THE TIME

[darryl]

I would suggest aginst the 9". As said, they are heavy, this will upset the
MX-5's handling, as would dropping in a 302 I might add. If you were to fit a
solid rear end and 4 link I would use a Hilux rear end. These can handle a lot
of HP and in a light car, a heavy 9" isn't needed unless you are going drag
racing with very sticky tyres.
Otherwise, I think a S6 RX-7 diff will be fine, if you have the money, get a
S6 housing and fit a KAZZ LSD, They may even make one for the MX-5.

[SG & NA Fisk]

I agree Darryl - I personally think 500hp is probably a bit optimistic. 300 -
350 HP is absolutely mindblowing in cars a lot heavier than a MX5 What do U
think a turboed 1600 would produce (& live more than a few Km) - You of all
people would know.
I have been in a supercharged 8 litre 9 second T bucket and it was a memorable
experience!
Stevan

[shaznandy lockyer]

Yes! TRUST in Japan spent many millions of yen on a EVO 6 Lancer and were very proud indeed to claim 570 hp and NO expense was spared...were you meaning power at the flywheel or roadwheels?500hp/ton is going to melt/warp your mind,license and senses...go for it

[darryl]

BD4's in Australia have a turbo 1600 MX-5 runnig a T28 BB Turbo, 1.1 bar
boost, intercooler etc and 8.5:1 compression, ECU mods etc and has put down
189KW at the wheels (about 230KW flywheel, or 308HP).
If you can build the engine to handle more boost, bigger turbo maybe, 350HP is
achevable, and I would say reliability may be a touchy word to use here but
depends on how strong you build the engine realy. The key is to use a good
sized intercooler, and a turbo that is in its efficency range at the boost you
intend to run, and of course, good tuning.
I think 500Hp from the given combination (from Milford Autoelectrical) may
work if they run a lot of boost, but what can the 1800 block handle? I have
heard guys in the states putting sleeves in the bores for strength (like all
the Honda guys do) and numbers around the 600HP been thrown around but thats
big $$$. I think the VR-4 I/C needs to go in the bin, too small for 500HP of
air flow, and to work well.
Personaly, my self being a rotary freak, if you do want big HP, I would just
drop in a mild 13B turbo for a lazy, easy and reliable (rotary, reliable, in
the same sentance??) 350-400HP.
But what do you want, a strip terror or a fast road car? Like you say, 350 in
a bigger car is fun, I think 300Hp in an MX-5 would be sex on wheels!

[shaznandy lockyer]

I Agree, Darryl
the 13B approach is very sensible.The MX-5 was judged the "best handling car in production in 1990 and adding i/c's, turbos & all that extra plumbing adds weight to the front of the car so unballancing the weight distribution and hence the fine handling of the car!A13B however will save a little weight and allow you to re-distribute your ancillary mass more centrally...Imagine the 0 to the left is the nose of your MX-5 and the 0 to the right is the MX-5's tail and the middle 0 is the cars' centre of gravity (CG)...[about 30 cm bellow the wing mirrors] "A 1kg mass carried at the extreme end of the overhang is equall to a 100kg weight near the vehicles CG..." 1kg 0-------------------------100kg--0------------------------------------0
and thats a quote from Mr. Takao Kijima,Program manager for both the MX-5 AND RX-7...
so if you wish to get round corners quickly, as the car was designed...
ryl <BITCHN.7@xtra.co.nz> wrote: BD4's in Australia have a turbo 1600 MX-5 runnig a T28 BB Turbo, 1.1 bar boost, intercooler etc and 8.5:1 compression, ECU mods etc and has put down 189KW at the wheels (about 230KW flywheel, or 308HP).If you can build the engine to handle more boost, bigger turbo maybe, 350HP is achevable, and I would say reliability may be a touchy word to use here but depends on how strong you build the engine realy. The key is to use a good sized intercooler, and a turbo that is in its efficency range at the boost you intend to run, and of course, good tuning. I think 500Hp from the given combination (from Milford Autoelectrical) may work if they run a lot of boost, but what can the 1800 block handle? I have heard guys in the states putting sleeves in the bores for strength (like all the Honda guys do) and numbers around the 600HP been thrown around but thats big $$$. I think the VR-4 I/C needs to go in the bin, too small for 500HP of air flow, and to wor!
k well.Personaly, my self being a rotary freak, if you do want big HP, I would just drop in a mild 13B turbo for a lazy, easy and reliable (rotary, reliable, in the same sentance??) 350-400HP. But what do you want, a strip terror or a fast road car? Like you say, 350 in a bigger car is fun, I think 300Hp in an MX-5 would be sex on wheels! Darryl Curran, Bitch'n Performance
3 Gummer Place, Morrinsville, NZ
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