My car is running a d15b7-d16y8 mini me swap with a p28 and I read somewhere that since the compression ratio is 10.something:1 it requires 91 octane to run without pinging. I somewhat question this but I don't know for sure if its true and I'm scared to try regular or mid grade. If I don't need to I don't really want to, So my question is do I need to or am I just wasting my money?

 

I would try a blend of octanes. Are you at altitude in Salt Lake, Utah?
I was in Denver once and I saw 85 octane.
I'm in Florida (sea level) so I need higher octane.
Try a little blend and drive around the block and listen for pinging.
You'll figure it out for your area.

 

The elevation here is 4,209 and the highest we have here is 91 I believe. Every time I go to the pump I always go to push the mid grade button then hesitate and put premium in instead. I guess the best thing to do is what you suggest. Put a couple bucks in then drive a short distance. I'll have to try that this weekend or something.

 

Run what your car was tuned for. If it isn't tuned, build yourself a det can and try stepping down to mid-grade. Run your tank until almost empty, then toss no more than a couple gallons of mid. If you hear detonation (with your new det can), immediately go back and fill your tank with premium. If you don't, give it a full tank of mid, and keep an ear on it.

 

Do whatever gas changing you must but not before you verify your mechanical timing at least, let alone the timing tables found within the ECU that could have been rendered by a previous tuner.

Or air being introduced from atmosphere into your intake track after throttle body (vaccum leak)

Just cant see a setup like that needing more than regular fuel.

One of the planets are out of line.

 

If this gives you an idea...
My old Prelude with H23 had a compression ratio of 9.8:1 and said plainly on the gauge to use Premium only.
Don't know if that translates to Ds.

 

Us gsr is 10.0:1 gas gauge also boldly states "premium only" unless you like detonation...

 

Hmmmm. I tried mid grade today and have been running it somewhat hard getting on the freeway and haven't noticed anything unusual. I put in 5 dollars worth of gas last night (like a gallon and a half?) and it seemed fine so i put in about 5 gallons of 89 octane. The car was never tuned, its running a stock p28 right now. I set the timing just this week so that's not an issue. Also whats a det can? I've never heard of that.

 

Spend 30 seconds on Google, then. Detonation Can. Block stethoscope. Block Mic. All the same thing. It lets you hear detonation before it, you know, blows up your motor. You'll look goofy as hell wearing it, but it's a hell of a lot better than a cracked sleeve or a snapped ring land. You can buy one for $50+, or assemble your own for <$20.

 

So your saying a stock gsr will ping on 87, 89 fuels???
You need to learn more about the ECU and fuel trims. And why they exist.

marc and yourself are referring to twincam higher reving engines that generate much more heat/energy as they climb towards those higher sustained rpms. Not to mention combustion chamber designs in the bigger motors are less forgiving in order to achieve the power they do, so Premium for those two cars for sure.
But OP's setup does not have these attributes that require the use of premium fuel. Although the condition of the engine/car and the fact that he is at higher elevation with less o2 in the atmosphere is probably the biggest contributor towards your pinging.

The only fix to this is to have the ecu tuned for your atmospheric conditions and fuel quality you have up there. Obv the ECU is not adding enough fuel to compensate for the lack of o2 in your atmosphere. I personally would swoop up a VAFC and dump more gas all over the pinging while running 87, until any signs of knock are gone. then enjoy your reduced fuel costs, and most likely power increase from cleaner more efficient burn

 

@beecee18. Yes my gsr runs like *** w/87 or 89 pings like **** with us motor and jdm @ sea level(plenty of oxy) and it obviously has a closed chamber head which I know for fact is better at resisting detonation.
Edit; so for now until I put s300 in I just run primo on phearable basemap.

 

So now your saying the gsr engine would be better at resisting detonation then a single slammer, lol.
The special combustion design of the GSR was implemented just to lower the knock threshold down some so it could even work to begin with.

There is no comparing a factory race geared B-series knock threshold to that of a D-series, period....

Your car would run like *** due to the JDM ECU that uses programmed values dependent on 95oct fuel ?!?!
Like I said its time for you to focus on how the ECU works in making compensations for qualities of fuel, atmospheric conditions, ect.

This is why it is crucial to tune that P28, he is rocking a 1.5L hybrid whatever....
So it needs the applicable values within the ECU tables to be changed to accommodate this, or make fuel adjustaments with AFC.

Thread done

 

I meant compared to other b's. Of course I'm not trying to compare a b to d, duh
I'm not running a jdm ecu, I stated jdm engine, thanks for assuming.
AND like I said, I haven't put in the S300 yet so just calm down, when I do ill figure it out w/o ANY help from a guy like you, thanks anyway for the attempted insults

 

Just a fyi: car can ping without you hearing it. I would not trust your hears 100% to know if your car is pinging.

My back ground is from turbo rotaries. Granted a N/A honda motor has a much larger window of safety.

I run premium in all my cars.

 

Which is exactly why you build/buy a det can.

 

Not trying to insult in any way, and I got the bold mixed up with us motor with jdm ??? so I just assumed ECU.
Not in the business of hating, insulting, or any of that, sorry you took it that way.

@Hwyix, I do also come from modern turbo ECU tuning where we actually have a PID to log knock count, I also agree about knock you cant hear which you mostly cant with our applications. These Hondas also don't have a knock stategy that makes corrections to timing.
Im sure not many around here are familiar with phantom knock also.

@Jbpnoman, or you can just watch knock sensor voltage. But just like Hwyix said, we are not really used to physically hearing audible pre-detonation. If you can hear it in modern turbo applications, it is real bad, and possibly to late.

 

I never said I have detonation/pinging I was just questioning whether or not premium was necessary for my setup.

 

If that is not spelled out enough for you then:


YES

 

refey, read through the thread. You're only about the fifth person to say that. OP doesn't seem to care about sensible recommendations.

 

newer cars have knock sensors and once the car/ecu senses ping it retards timing... so any car with a knock sensor will run to the fuel that is in it.. knowing hes running a p28 and a d series im sure 89 is fine. even with higher compression hes not making more then 130-140 hp..

 

lol? I didn't see where I threw out anyone's opinions and I did in fact try what people said besides the det can. Not sure where that came from.

My last response was in regards to Beecee's comment about fixing the pinging/knock which I didn't have to begin with.

Thank you for the help though, I wasn't trying to come off condescendingly.