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Dyno: Mx5/Miata FE-dohc swap 302rwhp 281ftlbs

8370 Views 31 Replies 16 Participants Last post by  fredio54
After a year and half I finally made it back to the dyno. Upgraded the intercooler to solve the high intake air temps, did some street tuning and got the EBC working. Made four runs at 16psi (what I've been tuning/running on the street) on pump gas with some ign/fuel tweaking. Hit a dead end on the top end - I think the 1.6 Miata/MX5 throttle body and manifold might be choking the engine. Looking at the HP curve, I think there's a bunch hp missing up top with this turbo and engine. - rob

engine: Bone stock FE-dohc 2.0L with FE3n cams on pump gas
ignition: stock 1.6, cas driven
emu: MiataLINK FM software
intake: 1.6 throttle body, 1/2 1.6 manifold on top of 1/2 Kia Sportage manifold, 3x12x18 core b&p eBay intercooler
fuel: Supra pump, rx7 550cc injectors (82% dc)
turbo: t3/t4 50trim 60AR stage3 48AR
exhaust: OE Mercedes internal gate with 2.5" exit to 3" exhaust with 200 cell metal core cat, 18" glasspack and turbo style muffler:
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Sweet! :tup: Karma for you! Do you have any pics of the car and engine?
Great results. :tup:
random images

and the IGN table for reference (divide by 4):
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Very nice looking setup. I like how you've built the intake manifold, very neat.
Rob, you suck :p

Mostly for linking all these pics when your project is linked from the sticky thread ;-)

Not a bad dyno, but while you were taking the piss out of my engine pics for always having socks in the ports etc, someone was clearly filling your inlet with some too ;-)

Time for that sweet alloy inlet is it? :)

I had no idea pics/car were linked in the sticky. But then I suppose everything mentioned prior to it's creation is linked (if the linker did a good job). :D

No socks, nothing in there, just a bad idea proven true. ;) Actually it's good idea if you like short shifting and a simple solution to packaging.
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you say it might be missing some hp in the top end. but the curve looks pretty damn good :)
I can only imagine what 300hp in a little Miata feel like:eek::tup:
what compression does your engine have? if 10:1, i was under the impression 250whp was the max you could hit on pump gas with out meth injection or another adder.

Thanks Brandon
Very very nice, good job.
how much does the car weigh roughly?
specs will be usefull for my build, cheers :D

I haven't pulled the head to make a positive ID on the compression, but I've looked in the plug hole and tried dragging various things across the piston top and nothing has led me to believe there is a dome (ridge). Add to that the fact that I had no sign of knock on any of the pulls with that timing on pump gas, and I doubt it's a high compression FE. But Fred thinks otherwise. ;)

I'm guessing (hoping) the car weighs about 2350lbs (1065kg).

Though I really want to continue to work on the power, the real issue is driveline. I've never drag raced the car, only done one clutch dump and in 2k miles I'm already on my second Miata/MX5 transmission. I think all the 4th gear tuning pulls wear hard on the little transmission with that much torque.
with mine the ridge was semi-obvious. i used a nice led flashlight and looked in the spark plug hole. there was a circle the size of the spark plug that was raised maybe a mm or so, but just enough to see.
Hang on, I thought you said it was 10:1, or is this yet another one of our amazing communication blunders?

Either way, it is a good effort on pump gas.

Also, 4th gear pulls lead to a grand total of NO load on anything except torsion on the in and out shafts. It's all the other gears that do it :)

There is a lexus quad cam 4.0 v8 tt in a caldina station wagon in NZ with a W series box behind it. The owner only floors it in 4th because all the other gears instantly die.

The 48 AR exhaust housing might be choking it above 5000. It would be interesting to compare a AR63 housing on the dyno. Is there any turbo lag or is it instant now.

I see how you retarded the timing at the torque peak.
No- you were saying something about all the jap FEs you'd seen were high compression. Mine's a jap, but I don't think it's high. You don't think excessive torque has an impact on the bearings? Because the transmission that came out took about 5x the effort to turn as the one that went in. Maybe it was a good idea to swap before the dyno pulls- far less drive line loss. :D

Larken- good point, and I'd considered it. It is a stage3 wheel, which should help on the top end. For daily driving it's very nice, no lag whatsoever. Boost onset is 1800rpm on the hottest of days in the summer. I have a stage3 63AR turbine housing but it's a ford 5 bolt, not a Mercedes, so there'd be some work involved to redo the downpipe and either going external gate or finding another internal (yuck).

Yep, pulling the spark and adding fuel pre peak brought the torque up... but you knew that. :D
Not in fourth gear. Fourth gear is straight through and there should be absolutely no side load on the bearings, just torsional twisting on the in and out shafts which wont do anything much.

I'll be abusing 4th gear in the ute a lot, 4th gear motorway power slides ftw :)

Not in fourth gear. Fourth gear is straight through and there should be absolutely no side load on the bearings,
Thats only on a RWD like the miata, not a FWD eh?
There is torque on the gear and syncro spline though.
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