how to REALLY tune whole engine

[acannell]

1990 daytona es 2.5 turbo

hybrid T3/T4 (super 46 in S60 housing and stage 1 turbine in .63 housing)

stock swirl head

UNPORTED exhaust manifold

2.5" swingvalve

full 3" exhaust with no cat

dynoed at 250+ whp at 17psi

so how do I go about getting EVERYTHING set to the right value? specifically:

engine base timing
camshaft offset (adjustable cam sprocket installed)
fuel pressure (AFPR with +40's installed)
spark plug gap
computer timing/boost/injector maps (FWD stage 3 installed)

I have a wideband O2 installed, and a 1600F EGT gauge on runner #4.

All my modifications are in. I want to get this engine tuned for maximum drag racing performance. How do I do it?

I'm guessing:

some kind of reprogrammable computer

some dyno runs

But whats the right way to adjust the other things and in what order?

[tryingbe]

engine base timing - 12 degree timing
camshaft offset (adjustable cam sprocket installed) - 0 degree
fuel pressure (AFPR with +40's installed) - Get a fuel calculator out and see what pressure is need for +40% and the stage 3 computer
spark plug gap - .030 - .035
computer timing/boost/injector maps (FWD stage 3 installed) - call FWD.

[acannell]

well THAT was easy now wasn't it?

stage 5 computer is enroute

so whats the point of an adjustable cam sprocket?

[tryingbe]

If you have your head machined, your cam is going to be off a little. Or if you want to move your power band higher. Or if you use an aftermarket cam that is off center line...

[moparzrule]

Go to the dyno to test the cam timing. Move 2 degrees at a time, make 2 pulls each time to make sure it's consistant. Whatever makes the most power just set it to that.

[crusty shadow]

advancing the cam shifts the power band lower in the rpm range, ratarding it shifts it higher in the rpm range.
if i were you id invest in some dyno time. find someone who has plenty of experience with 4cyl turbo cars, or better yet our cars. i wouldnt have blown my money on a stage 5 computer, would have been better off socketing the ecu and going with d cal- allows total fuel and ignition adjustability . someone who knows what they are doing will be able to wring every last ounce of power out of it with a setup like that.

[acannell]

i agree with you. but the stage 5 was a free upgrade since i already had the stage 3. i am going to get things stable with stage 5 and then look into dcal or something else that allows total control, and then find an expert and dyno time.

[xrattiracer]

on the adjustable cam sprocket- retarding the timing will almost always give you better 1/4 mile times. sure it feels slower because of having less power down low, but it more than makes up for it with more power up top. I run mine at 6-8 deg retard, and would run more if i could spin the engine faster to take advantage of it.

[tryingbe]

Quote:

Originally Posted by acannell i agree with you. but the stage 5 was a free upgrade since i already had the stage 3. i am going to get things stable with stage 5 and then look into dcal or something else that allows total control, and then find an expert and dyno time.

You already got the socketed ECU, now you just need chip and burner.

[moparzrule]

Quote:

Originally Posted by xrattiracer on the adjustable cam sprocket- retarding the timing will almost always give you better 1/4 mile times. sure it feels slower because of having less power down low, but it more than makes up for it with more power up top. I run mine at 6-8 deg retard, and would run more if i could spin the engine faster to take advantage of it.

You got an EGT gauge? Because with that much retard I bet they are hot.

[crazymadbastard]

Good question on can retard and egts, with ignition you are right about egts shooting up for sure. 8 degrees is a whole tooth on the cam right? One other way I heard to set the cam timing is to adjust it until you get the highest compression(psi).

[moparzrule]

9 degree's is 1 tooth, but close enough.

Cam timing has just as much affect, if not more so, on EGT's than ignition timing!

[puppet]

You should start with fueling and getting that right. Changing the timing, either cam or ignition, shouldn't need a fueling change. You can use the EGT and your WB to see what the engine likes.

[acannell]

thats really not as simple as it sounds...first off:

1- this engine regularly exceeds 1600F (the max of my EGT gauge) at boost as low as 14psi with AFR's in the 11's.

2- the wideband says 11, the wideband says 12...whatever

how am I supposed to figure out what the engine likes? just guess how it feels when I floor it? its all so imprecise...plus things change run to run...

I mean I can set it to some arbitrary AFR, like "well everyone says mid 11's is good", so I adjust it to that. Then EGT's are 1700F. Should I care? Or not? Who knows?

[moparzrule]

Timing and fuel curves need to be in correlation. You can have it pig rich but still high EGT's due to timing retard. Sounds like your ignition and/or cam timing needs more advance. Most of the ignition timing will need to be changed in the calibration, unless you aren't at 12 degree's base timing already.