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this setup is just plain wrong :D unless he is running to small flow turbine for power levels and has way to high EMAP also his exhaust/screamer is clearly compensating for something :D
So you may recall my bickering about not idling right after reflashing a tune... well I placed a short circuit strap over the rear HO2S output wires(not that I have a sensor connected at all!) and that solved it. Now it runs excellent. I was right that the ~2m of free ended wires were picking up stray voltages that ran havoc on closed-loop fueling till the ECU built right trims.
In case you weren't bored of my odyssey already, here's one more chapter: EWG chapter. I figured that my existing manifold can be saved and that I could graft a 45mm ext wgt on it... and I was right. While it looks like an afterthought(it really is, lol), it simply works.
I did manage to control boost this time, sadly EMAP hasn't dropped nearly as much as I had hoped it would. I guess this is the snakey nature of the manifold not doing me any favours. Or the restricted compressor housing.
This is on a 7psi spring alone, no electronic boost controller. I got afrs dialed in then grew tired and bored of faffing with ME so I left boost level tuning for another day. For the moment I'm happy that I can floor it at any time, any gear, any RPM, and AFRs won't jump over 11.2. Possibly running low 10s right now, but no measurement under 11 = no clue. I know it's (too) rich, but I'm willing to sacrifice some 20-30 nm for peace of mind.
Well, this setup can't possibly do any better but I'm half-contempt with it and there's a bonus... if I ever go nuts enough to do a REW swap, I have 90% set-up for 400whp with what I have now.
On this 6psi going down to 5 at redline ME tells me I should be doing 240whp. Falls somewhere short of my maths... but hey, what I'm comparing up against is by no means a low-level build. You surely know who/what I'm speaking of
Last edited by ciprianrx8; 04-07-2023 at 05:44 AM.
Dunno about that. You can't tune to get exactly same AFR all day every day at any RPM and boost, within + - 0.1 AFR. I am considering allowing up to 12AFR under 2 psi, 11.8 under 5psi, 11.6 under 8 psi and 11.5 over 8 psi. Given that I can't always find 100RON with no ethanol(sometimes its E5/100RON or E10/100RON).
So I guess that's that. I've polished up the tune and tapered boost up top while keeping a decent midrange. Boost cut(or reverted to spring) @ 7250 rpm. Redline limiter @8500 just to be sure I never hit a fuel cut while still boosting. I never rev that high anyway, my cluster starts beeping @7200 ish, being a 4 port one that had a 7500 rpm redline.
Still runs rich here and there but I'm contempt with that.
I'm thinking if more timing might help in this case. Might be that E10/100RON gas burns too slowly? This is what I run now, and never seen 1 degree of knock retard across the board:
that’s only the equivalent of 93 octane here in the USA ([ron + mon]/2) so not likely
what is more likely is the sealing is poor enough that the effective compression is likely a lot less than the theoretical 10 to 1 for a Renesis due to excessive blowby.
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A few psi will be coming from the pipe going to turbine and a few more from the exhaust system (which still isn't free flow). Most of the rest will be from the smallish turbo itself. I would be putting numbers into Matchbot and seeing how they align with the maths predictions.
Yes, but only 1.5 at 6000 rpm given that it hits 11 psi by 3100 rpm ish. For what it is and what I need it to be, a zippy street car, I'm more pleased than ever with the result. Sure, could/should have been much easier to achieve this. emap/boost was 4 before... holy f*** and I thought there was something wrong with my emap measuring setup.
Originally Posted by TeamRX8
what is more likely is the sealing is poor enough that the effective compression is likely a lot less than the theoretical 10 to 1 for a Renesis due to excessive blowby.
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Nope, engine does 100psi compression on all front rotor faces and 85 on rear(as I've cut my sideseals short on purpose, expecting high EGTs).
I'm thinking if more timing might help in this case. Might be that E10/100RON gas burns too slowly?
Flame front speed is independent of octane rating. Octane rating is only the fuel's resistance to ignition, NOT how fast the flame front moves through the combustion chamber. Lots of people erroneously believe higher octane fuels "burn slower," which isn't necessarily the case.
Flame front speed is independent of octane rating. Octane rating is only the fuel's resistance to ignition, NOT how fast the flame front moves through the combustion chamber. Lots of people erroneously believe higher octane fuels "burn slower," which isn't necessarily the case.
yes it is indenpendent of octane rating but is very dependent on the fuel type / fuel mixture, and AFR.
Diesels burns slower than petrol, gazoline is crazy fast (it has aprox 40-50 octane rating) , alcohol is somewhere in between diesel and petrol/gasoline .
not all equal octane rating fuels have the same burning speed as same octane rating can be achieved by mixing different fuels, or having one very very clean. E10 100ron burns slower than E5 100ron which is slower to non alcohol 100ron...
leaner AFR burns slower, richer burn faster.... that is EGT can be very high with lean mixture (it is still burning)
Nope, engine does 100psi compression on all front rotor faces and 85 on rear(as I've cut my sideseals short on purpose, expecting high EGTs).
Whether you did it on purpose or not doesn’t negate that it’s poor sealing due to excessive blow-by. Especially when it’s in addition to used components that are also contributing as the numbers show.
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RRP MK1 coils took a dump. I've had them on for 30k kms, and they weren't new when I got them. I later found out they were just rebranded GM something coils.
Pic. for clarity.
They started with a flashing CEL in the 1000-2000 rpm area; me in my usual smart-***-ness never gave it any thought. Then fuel economy took a hit... and lastly it would not run right in the 1000-2000 rpm range.
Found a busted coil on the leading plug, rear rotor. Matched with the DTC the ecu gave out. Took the time to give the spark plugs a scrub with oven grease cleaner and they should be good for another 10k kms. Running NGK 11 heat range all round and they never gave me any headache.
I'm now back on stock coils, but I've bumped up their dwell time to 3ms. On my bench @ 12V I've noticed a much stronger, fatter spark at 3ms, even 4ms but I don't want to push my luck now. I hope to get away with as little dwell as possible that won't give me misfires under 12-12 psi of boost.
If you are interested I can find the part number of mercury racing coils that have asmuch energy with 2s dwell that IGN1a have at 8ms dwell. They were never adapter to car enthusiasts market as even 2.2ms would toast them within few days, ans the 2 is the max... Ie should be run at 1.8max.. But that mens 100mJ energy at redline, while the OEM or IGN1a can only dream of that power.. And LS coils cant even come close...
IGN-1A are Mercury coils (original manufacturer is Mototron)
Lance Nist at Pantera EFI is the original distributor source and acknowledged guru for them, he can verify it if you’re in doubt. The difference in spec being stated is not correct according to all my information. Which goes back many years on here for this topic.
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Had the first trackday with this car and have to say it fared much better than anticipated. Pushed boost to 15 psi, filled up with 102RON gas and off we go. EGTs got to 930 with a one-time spike of 950C. IATs at 38c with an ambient of 31C. Coolant steady at 90C - kudos to me from 3 years ago for installing those SPAL fans and not the generic mishimoto which I've seen first hand as being worse than OEM. Oil temps, measured directly near the oil pick-up were 110-115C. 5W40 really is too thin for a summer trackday so I won't be doing that again too soon. When once I'd see 85-90psi of oil pressure, now I was down to 65psi. That doesn't sit right with me, not when pushing 360-380nm @ wheels.
The issues this trackday brought forth are:
1) boosting against a partly closed throttle body is bad news for everything from control to efficiency. I'll have to tweak my EBC to avoid that - at least the wastegate should open at spring pressure not at 15 psi. Should TPS < 30% then no need to have the turbo add more boost... this made cornering while boosting difficult.
2) found that my habbit of keeping the oil sump full isn't a smart move on the track. Hard right corners + lots of oil + boost + perhaps not the best engine ever = massive oil burp. Added a catch can and drained some oil for this, hopefully this won't be an issue anymore. Street driving never had me boost hard while cornering before.
3) EMAP sensor took a dump... again. Well, it has served its purpose and I've done away with the setup. I am now left with a spare input in my gauge set, and probably will remain spare as the car runs well now.
Deleted EMAP measurement setup. Added a oct bolted on the stud off the ABS pump. Breather hose goes towards ground. No oil (vapor) in my intake, thank you.
Other than that... it drove back home on its wheels so how much more pleased can I be?
That's a great result Ciprian. Especially well done making a setup that doesn't overheat under those conditions.
A few notes :
*Good setup of boost controller and adjustment of throttle maps can yield excellent mid corner throttle control. Better than any cable operated throttle. I have mine set to deliver 1/2 and full boost easily from the throttle only.
*A well setup catch can with plenty of airflow through large diameter pipes will eliminate any need to drop oil level. Assuming side seals and oil control rings are still good.
*Agree re EMAP ...it's really handy for getting your setup where you want it but after that it isn't really necessary. Although it will tell you if things go sour EG I realised my BOV was stuck open when emap increased once.
IAT is measured from the chargepipe feeding the throttle body. From beneath the BOV. Took apart an OEM maf, stole the IAT thermistor, placed it in a 1/8npt bung, wired to ECU and that's all.
The IAT in my maf is now not connected to anything.
I might wire it up and show it on my gauges, why not?
'bout oil burps, side plates and all that jazz. This engine I've built kind of poorly. I've left tolerances too great on the sideseals, and side irons were already gone through some years and miles. But well - it pushes 85-95 psi compression and starts hot drama free. Don't know for how much longer I'll keep this car since getting a new to me BMW F22 with a 3.0L 6 cyl turbo. That thing will smoke any rx8 in a straight line, and vice-versa @ first corner.
Last edited by ciprianrx8; 08-09-2023 at 02:56 AM.
IAT is measured from the chargepipe feeding the throttle body. From beneath the BOV. Took apart an OEM maf, stole the IAT thermistor, placed it in a 1/8npt bung, wired to ECU and that's all.
That sensor is quite slow - I'd bet the actual IAT climbs above the number you are seeing.
03-24-2023, 03:01 AM
