shaulinmathvader

iTrader: (3)

I read didferent stuff than my engine builder tells me.My question kis why can I take my timing up to 41degrees all across the rpm range to 7000 rpms with no knock retard whatsoever with trace fuel ofcourse. Unleaded race fuel.
I have 383 with patriot stage 3 heads with valve reduced to 2.055 to fit a stcok ls1 block. Cam is 250/256 .646/.629 106+4

I keep on reading that i need to take my timing back to the 20's and i will run better but The higher I go the faster i go. This is of course with 13.1-13.4 afr

wait4me

iTrader: (10)

Cam can make a difference and head flow can make a difference in the timing the engine will like, however 41 does seem VERY high to me. But then again, The cam might be too big for the engine causing a disruption in flow allowing it to accept that amount?

An example is, on the lsa engine cyl head, they have a section blocked off in the intake runner, This messes with the flow of the head, but allows for more timing because of that..


Have you put it on a dyno to see what it is doing? USUALLY the better flowing the setup, the lower the timing needed. Seems a bit odd to get that high of timing..

shaulinmathvader

iTrader: (3)

I bought the patriot stage 3 heads thinking that one day i was going to make a 6.0 block but that is still on hold. The only thing I can think of is valve shrouding. The valves were originally 2.08. The bore is 3.906. Since we knew the valves would hit we grinded them down to 2.055. So They barely cleared. So im probably not getting enough arirflow bcuz of that. Bu the problem is i dont have money to get the proper size heads

Texas_WS6

iTrader: (9)

I run my timing up to 36 degrees. Lots of people have found their builds like more timing. I personly think the max timing of 20 to 25 degrees comes from GM having to run the lower total timing due to increased compression. The higher compression promotes detination with pump fuels and lowering total timing helps to defete that. I might be wrong.

Keep in mind my engine is only 9:1 compression and I run race fuel all the time so even with boost I run higher then stock LS ignition timing. We found this "Sweet Spot" for my timing by using a dyno. More timing is not always the right thing to do. Every custom engine build will be different and the engines needs will be different.

shaulinmathvader

iTrader: (3)

im at 11.0 to 1 compression. Its just that I started out with 35 degrees and it ran slower but once i took it to 41 degrees it ran way 6 tenths faster

2TR

I would start at a realistic max target of 26-28* until you car verify (dyno?) that your increased timing of 41* (F* that's amazing and scary at the same time to me!) is really putting additional power to the ground that would justify your results.

Approximately $100 for a dyno tune to verify your engine is salvagable @ 41* of timing...PRICELESS!

shaulinmathvader

iTrader: (3)

Im gonna try a dyno. Ive been wanting to anyways since I dont even knoe where the cam wants to shift anyways. We shall. Fisrt I need to fix the car. Im getting the pesky p1635 code and the TPs low input code. And my scanner does not even detect a TPS angle or throttle percentage when I rev it. I hope its just the sensor

nandos_z28

iTrader: (5)

I would venture a guess that the added octane from the race fuel coupled with the high altitude of El Paso, both play significant factors in you being able to run so much timing. I could be wrong but from my understanding, running at higher elevations has the same effect as reducing compression (less air density), therefore allowing for increased timing values.

Just my guess, but I will be following along here to see what you find out. I know in a single case I've experienced only getting around 30* in the motor before it started getting knock. That is at 6500' elevation but only with 91 octane fuel.

shaulinmathvader

iTrader: (3)

This is of course on high octane fuel and open header exhaust. If I put the catback and only run on 91 octane my motor is pinging bigtime by 5000rpms. But on high octane and open header kits fine

Texas_WS6

iTrader: (9)

Again your build is custom and not a stock GM build. The fuel you are using and your ambiant coditions are factors too. If it loves 41 then it loves 41. As said before the best way to know is with a dyno. Every custom build and other factors are different. I for one do not believe in the low timing is always best for LSx engines. I only run enough timing for peak performance and no more.

Are you sure you are getting that timing delivered to the engine? Those codes might be changing your timing.

wait4me

iTrader: (10)

The low tps code is from your Torque converter at a guess.

There is a low tps table you need to change to fix that issue.

It is table C3907

JimDDD

What are you running for fuel?
Shell has an unleaded race fuel (URT Advanced) that's labeled 110 octane, but it's really more like a 116.

I've used it. It's better than C16, generally accepts more timing than C16 and doesn't kill cats or O2 sensors.

May be helpful since you're running a lot of timing, but it sounds like whatever you're running likes the timing already =o)

shaulinmathvader

iTrader: (3)

Havent found any shell here likle that. But as far as the TPS, the scanner doesnt recognize any throttle angle. And the I have both the 5 volts ref 1 code and the TPS low input. Gonna try changing it first because the prongs and the wirings look fine. I usually just use the turbo 108 octane booster found at autozone. Works fine

JimDDD

I'd like to offer an answer, some affirmation, then a suggestion:

1. On the Shell URT Advanced race fuel:
They don't have it at Shell gas stations to my knowledge, but there are some dealers in and around Houston. Where is a good dyno shop in El Paso anyway? I can't think of one. I do know there is a distributor out there who can deliver to shops in Texas.

2. I would definitely try TPS first if the wiring looks OK.

3. And, for the love of everything, stop using that Autozone "108" additive.
That "108" octane boost at autozone raises 93 octane to maybe 93.5 octane. Maybe. And it's almost definitely going to foul your plugs.

It's garbage...nowhere in the vicinity of "108". It's highly misleading (as all of the cheap octane bottles are), and none of those store bought additives raise your octane by even ONE full point!

(Many of them use misleading verbiage by saying things like "raises your octane by 6 points!" That doesn't mean 93 to 99. It means <at best> it might raise it from 93 to 93.6
That's what they mean by "points". Pure garbage marketing.

The only additive that is widely accepted is Torco because it actually does raise octane significantly (In fact, it's the next best thing to actual race gas as race fuel is much more consistent in that you don't have to mix it yourself), but using anything that raises your octane is useless if you don't tune the car for race fuel....
It won't do anything good or help you make any power without tuning....

IrocZTransAm

Yup, it takes 10 points to equal 1 octane #.
Car Parts in EP carries 101 Octane Unleaded 110 Octane Leaded
116 Octane Leaded Methanol M1. I think they are switching to Sunoco but not sure.

JimDDD

Shell has some really good unleaded race fuel in a 100, 105 and another called "Advanced" that replaces anything leaded up to 116 octane, but without lead, which is kind of a big deal

The obvious advantage is that it doesn't harm cats or O2 sensors like leaded fuel does, and the stuff has actually shown to work better than the almighty VP C16:

There are some videos with the fuel being tested here: http://www.youtube.com/partsgrabber

They just took on sponsorship of NMRA and NMCA events, so you'll probably see it a lot more in the near future.

gregrob

iTrader: (8)

Why don't you simply read the plugs...

LSxPwrDZ

iTrader: (4)

I wouldn't be dead set on adjusting the timing on dyno pulls unless you can really load the car down and do a full pass like you would on the street and track through all gears. One pull through one gear on the dyno will allow more timing than it would actually like at the track. I've tested this also.

To dial in timing on the dyno I slow the pulls down so that one gear pulls take twice as long to reach redline so that the engine can put some heat into the plugs.