[JLMounce]

Originally Posted by Squidward

I will check around with local chassis dyno shops. There are a few in my area. That seems like a better time/money investment than piles of trips to the strip. Thanks to you and others for the suggestion. I like what you provided about the methodical approach. I tried the idle afr adjustment. I got slight changes in vacuum, but it was pretty much ranging from 13-14" even as I adjusted idle afr target from 13.5 to 13.1, to 13.8. I finally settled on 13.4.

I was at the strip Sunday. I got 4 passes in before I called it good enough. I didn't want to break my car when I had a 25+ mile drive back home. I got data logs, too.

My street timing has 16*/36* timing, with 15* vac advance. I started my first run at 16/36, and put in a [email protected].

Next run I bumped timing by 2* to 18/38, which has almost always been good for a tenth and a mph or so. Instead, I got [email protected] (wrong direction)

3rd run I pulled the 2* back out, and changed WOT afr's from 12.2 to 12.1. I got a [email protected]. Half track mph was up 76.01 vs 73.66 from previous run. All of these runs were pretty much hot lapped, first run at 1051 am, and the last at 1110 am. All runs were 10 minutes apart.

My 4th run had no changes because I had to choose a dial-in for the trophy bracket race. I ran a [email protected]. I got knocked out by a guy who is waaay better at racing than I am. He competes in NHRA class racing, with a 301 turbo car that runs 12's. He had a lot of room to toy with me, much like a cat with a mouse. He cut a better light by .3, and I was slower vs. index by .2. So I made it real easy for him to tap the brakes just before crossing the finish line.

What cam are you running in the car? For what it's worth, my idle AFR is set at 14.1 and I run my WOT fueling closer to 13:1.

General rule of thumb is leaner will produce more power. Based on what you're saying here, it sounds like you may currently be at optimal spark advance. Might focus instead on fueling.

Have you run any logs of your runs? Running logs for the pass and comparing specifically intake air temp and the resulting cylinder temp can help equalize runs where you may be losing power simply to added heat if you're hot-lapping.

One more thought here. If you replaced a poorly tuned carb with the FiTech, it's possible that you may be increasing combustion efficiency by way of proper fueling and better spark control. It's not out of the question, that reducing timing may increase power as a result.

[Squidward]

Originally Posted by JLMounce

What cam are you running in the car? For what it's worth, my idle AFR is set at 14.1 and I run my WOT fueling closer to 13:1.

General rule of thumb is leaner will produce more power. Based on what you're saying here, it sounds like you may currently be at optimal spark advance. Might focus instead on fueling.

Have you run any logs of your runs? Running logs for the pass and comparing specifically intake air temp and the resulting cylinder temp can help equalize runs where you may be losing power simply to added heat if you're hot-lapping.

One more thought here. If you replaced a poorly tuned carb with the FiTech, it's possible that you may be increasing combustion efficiency by way of proper fueling and better spark control. It's not out of the question, that reducing timing may increase power as a result.

I tried richer because it was safer. I picked up a little bit of mph with the changes, so I thought I might be going in the right direction.

My carb was pretty good. It was a Quick Fuel 780 vac secondary. I simply wanted efi as the next phase of the relationship. I never got a chance to completely tune the jets for WOT, or tune the rate at which the secondaries opened up.

Cam is a Voodoo 702, 219/227 on a 112 LSA.

I see what you are saying about intake air temp. The 2nd of the 2 logged runs was a tenth slower, and I compared intake air temp at 3k rpm in first gear. 2nd run was 4 degrees warmer.

[JLMounce]

Originally Posted by Squidward

I tried richer because it was safer. I picked up a little bit of mph with the changes, so I thought I might be going in the right direction.

My carb was pretty good. It was a Quick Fuel 780 vac secondary. I simply wanted efi as the next phase of the relationship. I never got a chance to completely tune the jets for WOT, or tune the rate at which the secondaries opened up.

Cam is a Voodoo 702, 219/227 on a 112 LSA.

I see what you are saying about intake air temp. The 2nd of the 2 logged runs was a tenth slower, and I compared intake air temp at 3k rpm in first gear. 2nd run was 4 degrees warmer.

If you're gaining mph, you're going in the right direction. ET's can very a lot based on traction, but if you're in it through the entire run, the MPH should be pretty consistent. So changes there can tell you if you're going in the right direction.

In regards to power falling off, did it do so before with the carb as well? If so, there's always a possibility that's not tune or fueling related. It could be something like valve float occurring.

I'm assuming this is on your car that has the 350/#62 combo? That cam should be pretty healthy in that setup.

[Squidward]

Originally Posted by JLMounce

If you're gaining mph, you're going in the right direction. ET's can very a lot based on traction, but if you're in it through the entire run, the MPH should be pretty consistent. So changes there can tell you if you're going in the right direction.

In regards to power falling off, did it do so before with the carb as well? If so, there's always a possibility that's not tune or fueling related. It could be something like valve float occurring.

I'm assuming this is on your car that has the 350/#62 combo? That cam should be pretty healthy in that setup.

350 with #12's. I thought the combo was going to be healthier, but it hasn't been quite so. Springs are Crower 68404's.

Power also nosed over similarly with the carb. Seems great up to the 1-2 shift, could probably go to 5500. It then noses over up around 5k for the 2-3 shift. Maybe it doesn't have enough torque to keep winding it up with the torque load in 2nd.

What I am understanding is that the 20.6 afr on decel (limit of what it can detect, obviously leaner) is ok.

I will try the dTPS. Makes sense. That I can tune/test on the street nearby. Thanks!

[JLMounce]

Originally Posted by Squidward

350 with #12's. I thought the combo was going to be healthier, but it hasn't been quite so. Springs are Crower 68404's.

Power also nosed over similarly with the carb. Seems great up to the 1-2 shift, could probably go to 5500. It then noses over up around 5k for the 2-3 shift. Maybe it doesn't have enough torque to keep winding it up with the torque load in 2nd.

What I am understanding is that the 20.6 afr on decel (limit of what it can detect, obviously leaner) is ok.

I will try the dTPS. Makes sense. That I can tune/test on the street nearby. Thanks!

Yeah, if that symptom crossed from carb to FiTech, I'd look at non-tune/fuel related. I suppose it's also certainly possible that the engine is done by that rpm as well. Though I would think that cam would carry power a bit further.

And yes, the 20.6 afr reading on decel/coast is fine. There's literally zero fuel being put into the engine. The FiTech just doesn't have a way to show you "no fuel" so it gives you some stratosphericly high AFR reading instead.