GREGGPENN

Got my first scan today. 923mV was the highest reading on my O2 sensor during a WOT burst. When BLM jumped to 128, LV8 was 255 (in case that means I didn't get it to true WOT). I will check to see if a full-pedal press completely opens the blades tomorrow.

BLMs are 118. I think my injector constant and/or voltage might need a minor tweak. Otherwise, how could I be a bit rich?

I got 16 knock counts in my short drive around the block. At least half of them were recorded during deceleration,,,and at low 1000ish rpms. Sounds like some cam knock? (Wonder if RPM knock threshold should be raised?) I did get one knock count in the WOT run which retarded timing (from 32) to 29 degrees. (We figured AFRs wouldn't need much more than 32 degrees advance.) I thought it was weird that (.9 deg) timing started being pulled out at 32mph (I stabbed it 25mph), but the knock count didn't register until 2 samples later -- at 46mph. That's when timing retard maxxed at 3 degrees.

BTW: Timing still displayed full advance for the top LV8 row (32 deg for max LV8 in my tune). Why didn't it lower to 29 deg when 3 deg retard was registered? It stayed at 32. (This knock issue makes me wonder if I NEED the upgraded ESC module?)

mnstrlt1

gorgeous build! It came together nicely. I've got mine in the works, I feel like a mad scientist! lol..

TJM

About time!

AND..... You have the pretty twin sister of my motor. Same stuff, but BOY yours looks so nice.

The difference is going to scare you when you finally open it up.

I think the headers and the Siamese ported runners have a lot going on we haven't accounted for.

Think about it The intakes are eerily simialr to the exhaust?????

Got to be some voodoo math in there?

Can't wait to see the dyno numbers.

TJM

GREGGPENN

I never heard torque referred to as voodoo before. Next time there's a HP vs TQ thread,,,we ought to use that!

For now, I don't see it as voodoo. I picked the 4-2-1 headers to maximize torque. Same with the intake. Same with the head/cam combo. Mission accomplished...and then some.

I did finally open it up all the way today.

Wow....just wow.

(I may need to install the HSR just to lower torque! LOL)

lt4obsesses

You might need to break out that second set of rear tires before you planned.

TJM

I picked the 4-2-1 headers to maximize torque. Same with the intake. Same with the head/cam combo. Mission accomplished...and then some.



What I see as significant is how the ported runners Siamese in the same fashion as the headers Y?

I suspect the charges flow smoother and with less pulsation?

Could be voodoo could be science?

You are better at noodling out that esoteric stuff, so "Bug In Ear"?

TJM

GREGGPENN

Voodoo it is!




P.S. Is yours running? What heads are on it? Dyno?

TJM

Oh yes sir, it's been going since the TRI-Y thread.

No dyno, been too busy on the '84 racer and this '89 is my Garage Queen/ test bed.

Same set up as you, except stock motor & heads.

A 13.5 best at Atl Dragway last year, on drag slicks, shift kit in the auto, mild chip, and 3:07 gears.

Road Atl was more revealing. The '89 was effortless, very strong in the ranges run, 3,000 - 5,500 rpm. No hint of breathlessness. 2nd and Drive.

Hit 130 on the back straight and had more, but that's hard to measure under those circumstances. 1:53 was the best lap time. Brakes limited speed.

So from stock '89 performance I'd say just intake runners and headers did quite a bit. Borla racing mufflers and free flow cat didn't hurt.

Now I have to decide if I move this exhaust to the '84? I have a set of Melrose, so I can go either way? The '84 has a carburetor and won't need much torque help with the build we have, so the Melrose may just go on the racer.

Your set up should get you much more! Looks nice too, real good application.


TJM

Z51L9889

Congratulations, Gregg!!!

Sounds like it's a beast!

And yes, you did beat me ....

lt4obsesses

Well, I can say from first hand account that Gregg is correct when he says "a monster is born". Stopped by his place today as he was helping with a little problem I had on my ride. We decided to get some lunch while my car cooled down, and he handed me the keys to his ride.

First observation was the throttle response. Lightening quick, and smooth. It was like all I had to do was think it, and VAROOM! I will admit to being a little skiddish with it at first, not knowing what to expect. Didn't really want to fly into a tree or something. But the highlight was a quick 4-3 downshift manuever and 40-80 was almost instant and silky. It really doesn't take much to break the tires loose in either first or second. Idle is surprisingly smooth as well.

Other than really motivating me to get the tune done on mine, I also have a deep desire for a short throw shifter now as well. It reduces the effort of gear changing to about the equivilant of touching a button, compared to my stock shifter.

I recall that Gregg's goal was a streetable torque monster that would pull hard in third gear, with good manners in normal driving conditions. I think he nailed it with this build. Good job Gregg

Orr89rocz

LV8 of 255 means its working hard You shouldnt see any more than that, I dont think it goes any higher. 923mv is abit rich so thats good. Could definately lean it out some.

Its weird its pulling timing in that WOT range around 46mph. What rpm was that and do you know what the milivolt value was for that spot?
Was it around peak torque? It may be lean there and going rich up top or vice versa. Hard to say without doing a few WOT pulls and watching the milivolt trend. This is not the end all of tuning tho, a wideband and plug reading should be used to confirm.

What was your compression ratio again? I know you have a rather small cam and if you have higher compression it may not want more than 29 deg. I would have thought however 32-34 would have worked well with mid 10's to 1 compression and proper air fuel ratio.

Could also be false. You will see knock counts during startup and shutdown sometimes, but doesnt mean anything. Could also get it on deceleration I guess. Does it backfire/pop alittle on decel?

As far as being abit rich while cruise, it could be that the MAF is just alittle off calibration for that motor, or more likely cause is injector constant is alittle off or battery voltage offset table is just not correct for the new injectors. Either way you can just make a small change and tune that out. Could easily be taken care of with battery voltage offset IF the entire range of operation is just alittle off 128. If you have spots that are 118 and some spots 128 and some say 134, then you need to fine tune those spots with the MAF table and/or spark table tuning

enventr

looks and sounds nice job on the install

GREGGPENN

LT4Obsesses: Thanks for the feedback/observations. More importantly, thanks for reciprocating and letting me drive your hotcammed LT4. That made a really nice basis for comparison -- for me to judge what I'd accomplished!

Orr89rocZ: A good bit of time has lapsed since the post to which you responded. I've updated tables almost daily in hopes of learning what the new motor really "likes". LT4Obsesses drove the most aggressive table yet. Tomorrow, I will be lowering most cells 3-5 degrees to observe the results. (There are a couple of things I'm looking at). For the most part, I'm lowering timing from 36 (where Cuisinartvette said AFRs should be) to 32 where it may just be faster and more linear. All other timing cells will be dropped to observe knock counts, idle, off-idle, and cruise characteristics. Mostly, I'm looking toward improving driveability though I want to go back and see/feel how the lower timing compares in acceleration. (I was changing curves often enough, I didn't give myself a chance to learn what each change accomplished.)

Enventr, Z51L9889, TJM, et al: To see what I put the shiney motor IN, here's a new pic of what's been pulled out of the garage. I've bought a new camera since the pics I took 3yrs ago. I think it's time to show a hi-res pic of the car. Hope you guys like it and see why I felt it needed a matching power plant (in character that is)!!!

mnstrlt1

Greg- What I like is the Stock ZR1 wheels you're running (sawblades with 36mm offset). I think it's a great example for other corvette owners curious to know how the standard vette' will sit with 36mm offset wheels.

Great lookin' vette' and awesome combination.

GREGGPENN

Wow! Incredible eye or great memory.

GREGGPENN

I'm running 10.2SCR with 8.2DCR. 56cc heads with inverted dome pistons .040 quench...no sharp edges. Should be close to ideal.

No backfire/popping. I decided it's mostly false knock counts. (Especially when most of them retard something like .1 deg)

I tried all of that and got frustrated. Then, I went back and reviewed the link to the injectors I'd bought. Though I was told they were 24lb SVOs, I did the math. When I converted g/sec, I came up with an injector that flow 26.3 lb/hr min @ 39PSI. I just needed to raise the injector constant globally! That got my BLMs around 123. And, the INT was oscillating from 118 to 140. With further tweaks, I couldn't improve on that. (At least not w/o a WB anyway.)

I pretty much need to decide on a final timing map and I'll be done. I'm really wanting to get the ECM back up into the dash and finish the interior.

BTW: In case people are wondering. That's really an '89 in the pic above. I've also done a bumper upgrade, sidepipes, and Toledo Pro hood. And, there's still less than 60k on the car.

TheFinn

Greg,
in retrospect, would you still go with tri-Y headers or with more common 4-1 headers?

enventr

car looks awesome-any side view pix?

Aardwolf

Could be your knock sensor isn't working that well with the pipe thread sealant on it. You can test it by tapping on the block with a screw driver and data logging what it picks up. Be careful with the WOT runs without knowing the A/F! I ended up with 15% more fuel to get 12.5 in the upper RPM band as it would go lean with more RPM (PE VS RPM).

GREGGPENN

I like the way the Tri-Ys are performing. I would still choose that design for a street car.

My PE is set about 15% more than stock (esp above 3200 rpms). I kinda doubt my sensor is "numbed" by the teflon paste, but I might try you tap-test. Thx! And, thx for our conversation recently!