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Another thread about pinging on LH 2.4, 16T edition

Kjets On a Plane said:
With stock EMS, and generally, they're kinda junk as a hot-rod platform by today's (or kinda even late 80s/early 90s) standards...

IDK why anyone messes with them (even healthy FT versions) past 250-300hp for something vaguely pleasant and street able...
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My car made a reliable 315whp at 20psi on a stock ems, drove the car around for years at that level and beat it like it owed me money. I also did have access to e85 where I lived. All I did when I moved locations was take 3 degrees out globally on the ignition map and it was fine on 91octane.
 
TD04s flow horribly for the size of the engine. .63A/R cosworth housing or the stock .63 with the ATP gate and 60-trim compressor works nicely in a very mild 8V car of old/cheap stuff. You can do other things, but they can get expensive quick.

3 degrees is a lot of timing...what kind of fuel economy does one get running around like that? Might as well have a V8 muscle car that actually does get up and go i'd imagine and drive fine with the A/C on or whatever.

E85 is having to "know" something or do something special constantly (every fill up and not that consistent unless you constantly babysit it). How many TB +T hoopties still get 27-30 highway mpg and 22ish city unless beating on it, idle silk smooth same as it did with the T-cam and you can just go to any gas station like a boring B230F car and fill it without worry?

If the standard is "drive it without having to know anything special and it did everything it ever did before as well or better" I still maintain that 250-300ish HP and then it becomes cubic money and/or large compromises thereafter...

But the restrictive heads, stock EMS on the worn out +T engine and drinking straw TD04s everyone here seems to love don't help a lot either, even for a lousy 250hp or whatever.
 
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cosbySweater said:
I always ran bigger turbos. Also if you are on lh and have some e85 in the area try splashing a few gallons in. Tlao chips do help but with my experience a little rattle would always occur with the smaller turbo, the exhaust housing is also a huge bottle neck on the td04s back pressure is not your friend
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I was told that since e85 has less energy per volume than gasoline, that if you splash some in your tank and still run stoich or whatever LH runs in boost, you'll technically be lean and have more chance of ping.

And also you're saying that a bigger turbo, moving more air, is less likely to ping since it's turbine housing is less restrictive? How much of a difference does it make?
 
A big difference, and straight e85 yes you have to run a bigger injector but if you splash a few gallons in let's say 10gallons of premium and 3 gallons of e85 it dilutes it but it does still provide a slight octane boost. When I get near a e85 pump I'll do it and record a content reading
 
muppetman342 said:
I think his point is more the speed at which the boost comes on being the killer.
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Possibly. Or that the small housing has trouble evacuating exhaust gasses, thus causing backpressure (which is always bad on 4 strokes btw, na or turbo), and possibly even reversion. Reversion I assume would rise combustion temps a LOT, and cause knock. I may be overthinking this.
 
culberro said:
You're a bit off base. Read this: https://www.carthrottle.com/post/w96gzom/
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Wait where did I go wrong? I understand that the high load low rpm is bad. And these small turbos spool 'too soon', but I never boost below like 2500 or 3000 rpm. I downshift uphills and stay out of boost rather than using the boost to help me. Yes I still ping in high rpms.
 
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There will be a slight temp rise in the chamber, but not a lot (which is where you put the emphasis). Unless you're running stupid rich, there won't be anything to burn in the leftover exhaust gases (one of the reasons for EGR).
If anything, the dilution of the incoming charge will help prevent knocking. That is unless you have a glowing chunk of carbon or a hot spot somewhere.
 
culberro said:
There will be a slight temp rise in the chamber, but not a lot (which is where you put the emphasis). Unless you're running stupid rich, there won't be anything to burn in the leftover exhaust gases (one of the reasons for EGR).
If anything, the dilution of the incoming charge will help prevent knocking. That is unless you have a glowing chunk of carbon or a hot spot somewhere.
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You're saying that reversion reduces knock? When the exhaust gasses re enter the combustion chamber?
 
PromiseRing said:
You're saying that reversion reduces knock? When the exhaust gasses re enter the combustion chamber?
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It dilutes the incoming charge with something that will not burn. It's taking up space in the combustion chamber, and basically reducing the amount of good charge that can exist. This will result in a cooler combustion event, and reduced knock propensity by the fact that there's just less energy in the system.

Exhaust gasses are generally about 1/2-1/4 the temperature of combustion gases btw.
 
culberro said:
It dilutes the incoming charge with something that will not burn. It's taking up space in the combustion chamber, and basically reducing the amount of good charge that can exist. This will result in a cooler combustion event, and reduced knock propensity by the fact that there's just less energy in the system.

Exhaust gasses are generally about 1/2-1/4 the temperature of combustion gases btw.
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Okay that makes sense. So basically you're less likely to knock, but it will 'significantly' reduce power output. Any resistance to flow in the exhaust system costs horsepower because it takes mechanical energy to make the gasses flow (like the piston pushing them out). And that's why a fine tuned header/exhaust is so important for performance engines? The design will allow one exhaust pulse to pull another out of the chamber and help scavenge?

Also, why do people say their engine will knock if the exhaust is too restrictive?
 
PromiseRing said:
Also, why do people say their engine will knock if the exhaust is too restrictive?
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I have never heard that before. I guess it could come from having a bunch of carbon build up from years and years of incomplete combustion and overly rich carbs. I have seen that.
 
Update: so now I can get up to about 3-4 psi before LH enriches at all and I can hear light pinging. This definitely isn't right.

As I understand it, the enrichment point is purely based on airflow measured by the MAF. Is it possible that there's some resistance in the wires causing the scaling to be off? I'll be checking/measuring resistance tomorrow.
 
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