Miata Turbo Forum - Boost cars, acquire cats. - Just can't break the 200hp mark!

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Then something's wrong with the cooling system if you have to balance EGTs and CLTs. Go do an experiment - advance timing and lean out at cruise and I guarantee that the EGTs will go down.

As for the CLTs? Get a new radiator, seal mouth around IC and rad. If you've really gotta balance them, something is wrong.

Quote:

Originally Posted by rider384 (Post 645199)

That how fine tuning works. You tune based on EGTs and wideband.

I can guarantee you that you have a very flawed idea of how lean mixtures for some reason reduce egts and clt. And how advancing timing will reduce that as well. That is totally the opposite.

Quote:

Originally Posted by Rushin (Post 645201)

Lean mixtures burn hotter. This is true. But if it's too rich it will still be combusting when leaving the cylinder, and thus when in the exhaust, and thus hotter temps IN THE EXHAUST. I'm not talking about anywhere else except the exhaust. Same thing with timing. Retard the timing and it fires later in the cycle and the gas is still burning when it leaves the cylinder.

Yes, leaner mixture will cause extremely high temps in the cylinder, but a healthy cooling system should be able to cope. Leaner mixture means higher CLTs and engine temps.

Here's what Y8s said about it in a thread from a while ago:

Quote:

Originally Posted by y8s (Post 621871)

actually nevermind. mine's in the collector too. i was thinking of something else.

theres two things that primarily affect EGT: timing and air fuel ratio.

why:

retarding timing moves the ignition event later in the engine cycle. EGTs go up with retarding timing because the combustion event is still occurring as the exhaust valves are opening.

similarly, leaner AFRs tend to burn slower than stoich. as you go leaner, the burn is completing, again, after the exhaust valves are opening .. and more heat gest into the exhaust.

I suspect also that a relatively rich AFR may also be burning slowly or incompletely and carrying some heat out the exhaust valves.

The first thing I would do is correct your cruise fuel to something around 14.7 or 15.0 to 1 and re-check your cruise EGTs. I run 37-39 degrees of timing at 15:1 and my cruise EGT is closer to 1200. Advancing much beyond 45 degrees may not do much of anything.

Both you and that other guy need to read a little about how the this whole thing works.

If I was running too rich I would be backfiring and leaking gas out of the tail pipe (not that bad, or even possible) but I am not runing anywhere overly rich.

I have studied tuning enough to understan how it all works, just never bothered to make it perfect. I know the theory well enough but don't have the good enough knowledge of megasquirt or tuner studios to implement it. I am sure there ia another way to fine tune the cruising than just throwing fuel at the main VE map. I just don't know what it is. There is no book on how everything works in tuner studies.

Quote:

Originally Posted by rider384 (Post 645208)

I'll just let someone else chime in here.

Retarded timing causes high EGT, there's no real debate there. If you retard the timing, you make less power, which means more of the energy from the gasoline is produced as heat (by necessity). Thus, retarded timing = lower power = higher EGTs. It's a trick that tuners use to spool larger turbos - retard the timing way, way down to pump as much heat into the turbine as possible at lower RPM, and then advance it back up once the turbine is on song.

Leaner burn does lift EGT as well, provided we aren't talking about ultra-lean burn stuff. It's not as simple to explain - it has a lot more to do with gaseous barriers and basic chemistry than I can give a quick synopsis for.

Holy shit I can't believe how little he knows about the combustion process and how his egt's are affected by it yet is telling others "you got it all wrong":facepalm:

IF YOU KNEW WHAT YOU WERE DOING YOU WOULDN'T BE MAKING PATHETIC ASS POWER AND RUNNING LIKE SHIT.

So how about instead of telling people they don't know what they're talking about after you ask them for help you actually listen and read up on this shit.

You keep saying e85 has higher octane, runs better, more power, etc etc yet your car runs hot and is weak: exactly the opposite of how its supposed to.

This means there's a problem.

Retarding timing and adding gobs of unnecessary fuel at idle/cruise/partial boost, hell even at full boost will spike your egt's out the ass. That is a fact.

You really need to ditch that stupid fucking EGT sensor. You need to get your afr's into shape 1st thing. Then start perfecting timing.

I think the EGT gauge is distracting you and causing you to do stupid shit with your tune that is resulting in car running poorly.

Get AFR's into shape. Report back. if you get your tune spot on its only going to help you, not hurt you. even if it later turns out that it wasn't your tune.

I had a horrible time setting up e85 on my car simply cause I was one of the 1st people with an Adaptronic using it. I later found out that 100% of my issues were because of my own stupid fault = my shitty tuning. Now the car is strong as shit and runs like a champ. You have lots of reading to do.

You're sure that this turbo can hit 230whp but you can't do it. Upgrade that shit with something larger and just get it over with.

Dude - OP - You're in here asking for help, it's not helping your cause to argue with the people trying to give you advice. Remember, YOU are the one having trouble making your power goals. IIWY I'd sit back and let people brainstorm instead of shooting their ideas down.

Just sayin'.

Quote:

Originally Posted by Rushin (Post 644778)

Well e85 has a way higher octane rating, that fr starters. Pretty much proven to make more power if tuned well. Its safer because it does not detonate as early as pump 91-93 does. And it does not smell, biggest issueni had is because I am catless every time I come to a stop sign I wanted to throw up.

My ait are fine. The egts were high at cruise and afrs would climb to high 16s so I dropped them down to high 14s low 15s. And took the timing out in the cruise area.

Hmmmm........A clue......