like the title says, we blew past the map sensor on the first pull - the stock map sensor lol, made 379 at what we're guessing was around 18-20 psi. oopsies

running a precision 5831, GFB 44mm wastegate w/10psi spring, full 4" to 3" straight pipe to a single muffler, 70mm TB, 1650 injectors, flexfuel E85 (was fully on E for the tune/dyno), and running haltech. im around low 11's a/f when WOT in boost

engine has around 150k, she's happy. i tossed on the billman TCT for safety, engine has never been opened so stock HG. this is in my 85 rx7 and i have a 3.9 rear, which unfortunately runs my gears out (ap2 trans) wayyyy too fast. so i think an 8.8 is the next move with something like 3.55 gears or so

i could swap the map sensor and go back to retune to chase a few more psi and ponies, but it's reliable and fun as is, i dont think it'll be worth it. my rx7 weighs around 2300 lbs, i just want longer gears i think. thoughts ?

 

Your pissing away gas at low 11's AFR. Your engine would run just as safe at low 12's and actually be more efficient and should pick up some more power too as a result. It's better to have a proper tune at less boost then more boost, and saturate the engine with an over abundance of fuel. But either way, 10psi isn't a lot. if you were pushing on the ragged edge say 20psi, then sure, throw everything and the fence at it to keep the engine combustion as cool as possible with over fueling, but even then it's a band aid. Over time (and not that much time) you're going to be left with a lot of soot and carbon build up on your valves, piston tops, exhaust system and sensors. Basically a dirty engine running that rich. Which isn't good for the life of the motor either. So in essence your being counter productive to your goal of optimum reliability and longevity. Just my 0.2.

I wouldn't guess the current gearing to be too short, not at just 320whp. Considering the stock 4.10 in the s2k. The first 4 gearing the ap2 trans does have a primary reduction gear unlike the ap1 trans, which i calculated some time ago to be equivalent to 4.22 rear end ratio. So your 3.9 effective is right in the middle at about 4.00. At just 2300lb car, however, i suppose it motivates a bit quicker then a 2800lb s2k, so maybe a 3.55 would feel better to you. Probably just personal preference at this point.

 

tuning and a/f's are where my talent falls short. i have no idea what's good and what's not
i suppose i could get the higher map sensor, go back for a retune and push 13/15 psi or so and have to tuner aim for high 11's / low 12's a/f ?

i need tires - looking at the mickey thompson s/s @ $240ea, i'd liek to do the 8.8 swap so my rear holds up, otherwise all of this is pointless if im just gonna be braking rears lol

maybe after that we'll go back and tune. im also in the middle of putting a LSA on my '13 caprice (6.0), dropping my k24a2 (rbb jap engine) into my ae86 and im starting to piece together my k24 swap for my 92 s13 coupe. money is important but what i really need is time lol

 

Just wanted to give you some food for thought. Sounds like your tune is safe, so thats the main thing for now. Also agreed on the rear end. The rear s2k diff is not particulary strong, and you will go through them if your hard on it. Sometimes its better to have less sticky rear tire and break them loose then hook and brake your diff. Keep power and traction and your launching reasonable and you can avoid blowing it for a while, but an 8.8 would be the better long term solution and allow you to increase your power and traction.

 

oh! so im not running the s2000 rear
im using a GSLSE rx7 rear end. 3.9 gears, solid axle.
i broke a GSL "small axle" 4.10 already lol
8.8 will be next

HP increase. i put a SoS map sensor in it to replace the oem honda unit,, i went to JE in baltimore, we made 356whp @10psi before my clutch started to slip. im using the oem s2k flywheel which iirc had some heat spots on it. im 100% sure that's it
im running a clutch masters 6puck, that surely isnt my issue. gonna wait til some black friday sales go live and pick up one of those 11lb flywheels to swap in then go back at it. 356whp feels amazing though!!! i just want longer gears, seems like i run through them quick haha i think when i do the 8.8 ima go down to like 3.77

 

Sounds like a fun build. At ~2300lbs that's light. My car is somewhere around 2800+? For gearing it's really just personal preference. I'm running a 3.63 in my ap2 (f22 also has the lower rev limit and little better low end) and it's the perfect balance to me for the street. I'm probably right around your power level as well. Considering you're ~500 lbs lighter, I could see the 3.9 feeling a bit short.

 

I make around 320whp on 4.5 PSI and it's been pretty reliable doing track duty. I did tune it to about 400whp, which was about 8.5 PSI and I'd be perfectly comfortable running that at the track, but it just drives so well at 4.5 PSI that I haven't swapped the map on track. My car is about 2,700 lbs.

On E85, you should be targeting ~12:1 (gas referenced) AFR. You'll gain power by leaning it out as well.

 

Are you on e85? Which EMS are you tuned on?

 

Yes, I am running E85. I am currently on an AEM v2, however, I am swapping to a Haltech Elite 1500 here soon. I've got an extra on the shelf and figured I'd swap over.

 

320whp on 4.5psi is fantasy land even on E85 tbfh.