Got the new 4.3 motor tuned (updated w/initial dyno results)

David Neibert

SCCoA Admin
Dave Dalke traveled from the Dayton meet to my house late Friday night/Saturday morning to tune the new 4.3 motor in my 91.

We spent several hours road tuning the car Saturday to get the startup, idle and part throttle fuel trims all dialed in. Since we had a dyno appointment at 3:00 PM that afternoon we didn't even mess with the wide open throttle stuff, and were planning to use the Mustang load bearing dyno for that portion of the tuning. A quick stab of the throttle confirmed that the 3" blower pulley (was 3.25") had brought the boost up from 17 pounds to the 20 pounds of boost I was wanting.

Mainly because of that extra boost, it didn't go real well on the dyno because everytime I tried going WOT the motor started banging out and sounded like it was backfiring. Fuel was actually going leaner instead of richer whenever I would drop the hammer at 3100 rpms. If I gradually rolled into the throttle it was okay for a little bit but once it hit full boost it would start banging out again.

Apparently the MAF voltage was going very high as soon as I hit the throttle and the calculated load or something was exceeding 200%. Dave did something to force the computer to supply more fuel, but even at 11.4:1 A/F ratio it kept banging out everytime I gave it full throttle. At that point we concluded that in addition to the computer issues we also had an ignition problem, so we terminated the dyno session.

While I was getting some new plugs and cooling off the motor, Dave was busy doing some rescaling stuff to the tune to get the load calculations or VE numbers down to a workable level. I don't really understand what he did, but I know it's not something that's normally required o the other SCs he's tuned.

Bought some new plugs and gapped them .010 tighter and when installing them Dave found that one of the plug wire boots wasn't fitting tight and looked to be damaged from arcing through the boot into the dipstick tube.

Once the plugs were changed and the rescaled tune installed we took it back out to test the WOT stuff on the highway. Between the plugs, repairing the damaged wire and whatever majic he did to the tune...it worked. No more banging out....just a good strong pull up to the point that I decided to let off before risking a trip to jail (about 110 mph) :eek:

By the time Dave left to go home Sunday morning he had it, starting good (hot or cold), idling good at a lower rpm, and really ripping at WOT. The only issue remaining was the motor running hotter than normal. In an attempt to improve cooling at highway speeds we removed the GM air dam and installed the Magnum Powers chin spoiler/air dam. This was a real pain because of my lower radiator support sheet metal being bent from being winched onto a flatbed several years ago. With a little tweaking we got it on and it looks much cooler than the GM air dam but didn't really help with the cooling.

That's when Dave pointed out how removing the AC condensor without doing something to fill the gap around the MP FMIC was likely the reason for the cooling problems. Basicly there is a huge gap around the sides of the intercooler/radiator allowing air coming into the front of the car to bypass the radiator. The result of the air bypassing the radiator is that the under hood area is no longer at a lower air pressure than the air in front of the intrcooler and radiator, so the only thing promoting any air flow is the fan itself, and that isn't enough to keep the motor cooled at highway speeds. My fan shroud is also not sealed to the radiator core on the top and bottom and the 1/2" gap is really killing the fan peformance.

Since we didn't have the ability to dial in the WOT timing on the dyno to see just how much the motor wants, we guessed and left it set fairly low. It feels real strong and based on some of the air and fuel consumption numbers that Dave provided, I don't think it's going to be a problem reaching my performance goals. Planning to go back to my usual dyno to make a couple pulls sometime this week to see what it's doing now and will do the final tweaks to the tune the next time Dave is avalible.

Big thanks to Dave for making the special trip to STL to get me running right.

David

PS: That Quarter Horse and Binary Editor stuff that Fraser helped develop worked great for tuning my car. Doing on the fly changes, monitoring and data logging made the process much easier and more accurate than how my car had to be tuned in the past. I think this tuning package is going to be far superior to anything we have had in the past.
 
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Glad things are working out! Pretty stoked that the QH is working well. Nice job Fraser.
 
Sounds great David. I had heard Dalke was going to be here on Saturday, but there was no way for me to pop in since I was tied up with a morning funeral and an afternoon wedding.
 
Glad you guy's figured out the problem! Must be nice to have her running strong and healthy! Does it feel like the additional cubes has helped?

When will she be seeing some track times?

Congratulation!

This community is lucky to have guy's like Dave and Frasier!:D


Stephen
 
Sounds awesome, David. Dave is working on a 4.2 for me to replace my current dead engine and your progress is making me jealous.
 
Excellent. I love it when a plan comes together. I am glad to hear Dave found a way around the calculated load issue so you could get this done in one trip. Cannot wait to see it run.

Ira
 
Does it feel like the additional cubes has helped?

When will she be seeing some track times?

Stephen

Stephen,

It certianly feels strong, but I can't really say that it feels x amount faster, because I haven't driven the car at WOT since mid September of last year and I've been driving the turbo car a lot more lately. Compared to my 93 it feels pretty tame, but that car has alot more horse power and even more torque.

That being the case, my butt dyno is not helping and I won't really know what it's got until I see some dyno or track numbers. Not planning to race it until it's got another 300-600 miles on the motor, but I will be getting it on a dyno as soon as my schedule and the weather will allow.

David
 
Yeah, I quess when you get used to driving a stroked, turbo'ed SC I can see how the 6 would feel a little tamer!:eek:

Good luck on the WOT stuff! Get it dialed in.

Stephen
 
Sounds awesome, David. Dave is working on a 4.2 for me to replace my current dead engine and your progress is making me jealous.

Will,

I saw your new motor and heads when picking mine up. Looked like the same setup I got. I think you will be happy with it.

David
 
Glad to hear it, David. I'm really looking forward to the new engine. My CTS-V is fun but it's no Supercoupe.
 
Put the car on the dyno this afternoon to see where we are starting at with power and to double check the A/F ratio. Engine was pretty hot from the drive to the dyno but it still pulled a respectable 414 rwhp & about 430 rwtq with A/F ratio holding a steady 11.6:1 for most of the pull. While I would have loved to see the starting number closer to 440 rwhp, I didn't really expect it to do much more than it did, since we haven't done that portion of the tuning yet.

On a cool motor it only has about 22 degrees of timing and when it's as hot at is was when the pull was made, it's only around 20 degrees. Safe, but not enough to make the power numbers I'm looking for. Once I get the cooling system issues corrected and finish breaking in the motor, I'll be looking to have Dave dial in tune and see what it's really got.

I'll let you guys know how it turns out.

David
 
David...

Not to hijack a thread, but what are the specs on your turbo car- injector size, turbo, yada yada.. I'm gonna start going that route soon on mine.
 
Put the car on the dyno this afternoon to see where we are starting at with power and to double check the A/F ratio. Engine was pretty hot from the drive to the dyno but it still pulled a respectable 414 rwhp & about 430 rwtq with A/F ratio holding a steady 11.6:1 for most of the pull. While I would have loved to see the starting number closer to 440 rwhp, I didn't really expect it to do much more than it did, since we haven't done that portion of the tuning yet.

On a cool motor it only has about 22 degrees of timing and when it's as hot at is was when the pull was made, it's only around 20 degrees. Safe, but not enough to make the power numbers I'm looking for. Once I get the cooling system issues corrected and finish breaking in the motor, I'll be looking to have Dave dial in tune and see what it's really got.

I'll let you guys know how it turns out.

David

That's good stuff. Glad to hear it's coming together.

Ira
 
Was that on pump gas (91-93)? I think those are very respectable starting numbers.

Yes..93 octane with methanol injection. I agree that they are good starting numbers and I'm real happy with how the motor starts and runs perfectly. Just runs hotter than it should, but I'll be fixing that very soon.

Dyno guy said it looks like it needs more timing or less methanol. Methanol is already turned down about as low at the settings allow, so rather than guess at what it needs, or experiment with tunes long distance...I'll wait until we can tune it properly.

David
 
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Whoa....I'd be tickled silly to end up with close to that number, much less start there and have more to look for---great job to both the Daves............Dan
 
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