Nicelysedate

iTrader: (3)

I posed this question on the Hptuners Forum and figured I would ask here too.

I am working on a friends car trying to save him some money. I have tuned a few gen 3 motors with good success. I had my mid sized cam, LS1 Trans AM trapping 120mph all motor.

My friends car is a 2005 CTS-V Manual with an iron block 6.0, it has the following mods

- BTR stage 2 cam
- Trickflow ported 220's
- Fast 92
- Ford Racing injectors (Red Tops)
- ARH Headers
- Stock Exhaust with no cats or mufflers

Static compression is 11.18:1 and dynamic is 8.7:1


I have the car running @ 12.5 - 12.8 AFR at WOT and the fuel trims are spot on. Total timing is @ 28*. Torque management is gone.

We did 4 pulls on the dyno and the first was 363hp @ 6400rpm, last was 404hp at 6500rpm with me only making a minor fueling adjustment and adding a little more spark. He just went to the track at trapped 110 mph and was slower than a LS6 beside him with a much smaller cam.

Only thing I can see is the dynamic airflow is low compared to other logs I have from similar vehicles. It tops out at 2554lb/hr during the 4th gear pull.

Wondering if anyone sees anything in the tune.

rpturbo

iTrader: (47)

Was the cam degreed in? Sounds like the initial cam timing is off, just off the top of my head. I have seen it over and over and over. My can is the ljms cam, (BTR and LJMS use the same cams) and mine was a total of 5* off.

Nicelysedate

iTrader: (3)

I asked him to check it. He was certain he was dot to dot. I am thinking he is off a tooth or the throttle body isn't opening all the way.

subeone

iTrader: (5)

i wouldnt be surprised if you made more power with less ignition timing. 28* is a lot IMHO. nonetheless, something is off if he is trapping 110. are all cylinders firing? put a temp gun to each primary.

Nicelysedate

iTrader: (3)

O2's don't look like there is a misfire. Bank 1 and 2 fuel trims are quite close. As far as timing, LS motors seems to like 28*, that is the factory WOT timing for a LS1. The builder actually suggested 30*.

LSX Power Tuning

iTrader: (4)

I agree. On cars we re-tune that were tuned somewhere else I bet 99% of the time we make the same hp or more hp with less timing and almost always end up going fast at the track. We hardly ever see one make the most hp with 28 deg with today's gas, we are usually in the 25-26 deg range on a loaded dyno or at the track going off trap speed.

subeone

iTrader: (5)

yep! have had similar experiences, especially with a DCR that high and SCR in the 11s and a somewhat heavy cts v car. More efficient heads needs less timing. You have TFS 220s, so i'd be inclined to believe you need less ignition timing. BUT it's not the reason you are missing 50-75 ponies or so.

rpturbo

iTrader: (47)

Not just dot to dot, actually degreed in, with a degree wheel? Throwing timing in on a combo that is not mechanically correct, isn't going to work properly. I have nothing against the BTR/LJMS cams AT ALL, but I have not seen one ground accurately yet. I love my cam, and the same cam pushed Denmahs Colorado to almost 1000 rwhp off the juice, just saying I haven't seen one right yet is all, and it's certainly worth checking.

Nicelysedate

iTrader: (3)

Thanks for the replies all.

I am going to try taking a 4-5 degrees of timing out. I don't think it is the reason either that the build seems off 50-60 hp, but i'll give it a try.

As far as putting the degree wheel on. I was told the builder did do it. Of course the builder says there is nothing wrong with the build and it has to be the tune. But I think I would actually have to put quite a bit of effort in to sabotaging the tune to get it to be 60hp short....


After looking through a bunch of logs from other cars and from a few of mine, his dynamic airflow seems awfully low. So either the injector data is off (which I doubt as it is from Greg Banish's spreadsheet), or there is an air restriction, or a mechanical problem.

Old Geezer

iTrader: (3)

Timing vs plug readings show??

Nicelysedate

iTrader: (3)

Plugs look perfect. We have pulled them several times now.

ddnspider

iTrader: (26)

Where does power peak on the dyno? I.E. as expected or early? If early that would support the timing chain off a tooth. If the plugs look good and the tune is good, why not do a compression test? You said the dynamic airflow looks low, how much air is it consuming via the log? I don't have HPT on this PC.

Nicelysedate

iTrader: (3)

Power was still climbing at 6500 where we stopped the pull. It did flatten out around 5500 on all 4 pulls.

Compression was 210 +/- 5 on all cylinders.

Dynamic peaked at 2500lb/hr on the pull which seems low.