edomund

I finally started my reman motor today.
See my setup in my sig.

I was only letting it idle (no throttle) for around 10 min. (to go easy on the fresh motor).

When the motor got up to operating temps I started hearing what sounded like popping (pretty quite) like the sound you hear when you turn a car off after long drive.

Could this be detonation?
Is this sound normal?

I have a S-AFC and four Greddy 720cc injectors I don't know how I could've been running lean at idle and with no boost.

BTW Everyone told me to lean out the S-AFC to -15% but I had it at plus 5% to be safe.

What should I do?

ilike2eatricers

Wouldnt it be safer to leave all the settings at zero until you break it in and have a chance to dyno tune it. I am not sure about the sounds though. The popping after a long drive is from the exhaust expanding and contracting due to heat... I dont think it is related to your popping sound. I could be wrong though.

edomund

"Wouldnt it be safer to leave all the settings at zero until you break it in and have a chance to dyno tune it."

I set the S-AFC a bit rich just to be safe. Running rich wont harm anything.

"The popping after a long drive is from the exhaust expanding and contracting due to heat... I dont think it is related to your popping sound"

I just used that as an example of what my sound, sounds like.

Thanks for the input though, anything helps.

BobbyRX

My car isn't a turbo but when its idling I get a slight popping too, especially after the new exhaust was built. Are your dashpots hooked up (the anti-afterburn ones on the throttle body)? Mine blew the vaccume lines off and it would pop at every shift, at idle, whatever. It was a popcorn maker.

Forgot about timing... Do you have it set at the yellow mark or did you advance/retard it at all?

edomund

Timing is on the yellow mark.

All vac lines are hooked up with new silicone lines.

Sounds like it's coming from the exhaust manifold to me.

slow87turbo

what kinnda port do you have. they all pop a little its just the mature of the car expesially if you are running rich. its baby flames they just cant make it out of the manifold.


ej

edomund

stock ports on a 87 T2

what does detonation sound like then?
is it loud? how loud?

BTW Thanks for the help guys
Ed

SonicRaT

iTrader: (6)

You won't be detonating at idle.

edomund

Thats what I thought.

I was just being paranoid since I have been building this car for over a year and this is the first time I have actually seen it run.

I had a 86 GXL but I'm new to boost.

So you think it's just flames like slow87turbo said?

SonicRaT

iTrader: (6)

running 720's at +5% at idle? Yeah....

edomund

cool im running it right now!

My bro is watching vitals while I ran inside

gotta go

NZConvertible

No, I told you to run it at -24% to get it back to stock mixtures. With four 720cc/min injectors tuned at +5% you'll be running extremely rich, and I'm surprised it runs at all.

If you want to be safe, run it at -20% across the board (that's richer than stcok) and stay below ~10psi boost. Get it dyno-tuned ASAP.

ViperKillerWannabe

Running rich can cause detonation too. Carbon buildup can cause "hot spots" that cause preignition.

edomund

I know thats what you told me.
I was talking about scott he said -15%.

I don't have a FCD or Walbro thats why I was going to run the S-AFC at 0 or 5+.

When do you usaully get into boost?
What rpm or amount of throttle?

Right now it shows no boost but I only reved to around 2500 rpms

NZConvertible

Then there's no point in having bigger injectors. The fuel pump cannot maintain enough pressure at higher boost, so even with bigger injectors it'll still run lean. And without an FCD you can't get anywhere near the limit of the stock injectors, pump or ECU.

No offence, but you're doing your fuel mods in completely the wrong order. You're also running mixtures so rich you may do as much damage as running lean.

edomund

I'm not doing fuel mods in the wrong order.
It just worked out this way.

I had to get new injectors because it was a fire car so I went ahead and got 720s insted of buying injectors twice.

The only reason I dont have a FCD or walbro yet is because I dont need them with no boost (breaking in motor I have to stay off boost anyway)

I can put in FCD and walbro before I am done breaking in the motor before I start boosting.

I listened to you on the mixture though and leaned it out it runs smoother now.

Now you see the method to my madness

edomund

NZConvertible
So you think I should run at -20% (staying out of boost of course, because no FCD and walbro, as well as breaking in motor and turbo).

I'm at -11 right now and it seems good.

NZConvertible

Personally I'd put it at -24% so you're not throwing away good gas for nothing. If you're running then engine in (and can't boost past 8.6psi anyway) then there's absolutely no need for such rich mixtures.

But if you're happy with it...

edomund

*Yeah your probably right I'm just parnoid of running lean. I'll try leaning it out a bit.
What should I look out for when running lean?
Signs? Will my engine temp rise, noises etc.

*Also let me see if I understand. Even without a walbro I'm still running rich down low (with 720 primaries) because the stock pump can provide the 720s with enough fuel untill you are boosting hard.
So as long as I'm not boosting I'm going to run rich with my 720s regardless of stock pump, correct?

Thanks for the help NZConvertible
Ed

NZConvertible

Detonation.
Yes.
Without tuning, you'll run rich even if you are boosting.

edomund

First off, NZ thanks for your help again, it's my first turbo RX7 before this I had a 86 GXL.

I realize I should look out for detonation when running lean. I guess I worded my question wierd.

I meant what are the symptoms/signs of detonating and or running lean?
Like maybe engine temps, sounds (I dont know what detonation sounds like) etc..

NZConvertible

Other than detonation, you really can't tell while driving. Under load you might not even hear detonation because of exhaust noise.

With your set-up the chances of detonation are slim so I wouldn't be too worried.