melchoir

iTrader: (4)

How much power would a car lose running at 21* WOT, vs 28* WOT.

Roughly how much power would be lost running lower timing like that?
What are the effects of lower WOT timing on an NA motor setup like mine? (Bolt ons, TR224 cam only.)

If it was at a track would there be a substantial gain from 21 to 28 in normal circumstances?

Doc

iTrader: (9)

A metric ***-ton.

SSpdDmon

iTrader: (10)

Let's put it this way...I picked up 10rwhp just by going from 29* to 27* on the dyno. It works both ways. The wrong timing is the wrong timing. Running 21* of timing on that cam might make the car feel slower than stock - unless your plan is to hit it with a 150-shot.

zapp168

iTrader: (7)

But seriously, is there any good way to tune spark on the street? Other than running at the track?

Doc

iTrader: (9)

Gtech RR w/ serial output to measure torque output gaines or losses.

LS1curious

the three critical components in the equation are as follows.

1st chamber
2nd compression
3 rod length

chamber have an ideal flame front speed. although quench can help a lazy chamber its not a cure all.

Comrpession will affect intial flame front propogation in the chamber uptill it hits it maximum flame speed.

rod length determine where your stroke effective work relative to piston dwell.

Now here is a fiarly common exmplae a bad combo of parts.

11.5:1 l92 with a 4inch arm with a stock chamber and a 6.125 rod.

your rod ratio is 1.58 its gonna need alot of advance to get the flame front to give it optimal advance. roughly 32-33 dgerees. Your piston speed is higher this also requires a higher intial spark lead.

the stock l92 chamber is actually a good bit slower of a chamber then a standard ls1 chamber. this is neither good nor bad but must be kept in mind when

slelecting compression ratio. Compression ratio is very critical here. you can't run a ton of compression on an octane limited fuel like 91-93 octane with this much compression becuase all it will do is knock.


This particular comboination of parts I saw once and when i saw what the engine was doing i immediately realized what the problem was.

Now factor in the cam timming and you running Ve's and this gets very hairy very quickly.

So to answer your question Optimal spark is optimal spark if the motor wants 21 then 21 it is.


But you must make sure to match the rod ratio, chamber flame speed and compression ratio and you'll get good results. Now the one factor here is the influence of cam timming on optimal spark.


If you running a stock 346 ci engine and it needs 30 or more degrees of spark with stock chambers your camshaft is out to lunch at the stock compression ratio.


I would have to say that optimally speaking the factory Ls1 chambers rod and bore combo really needs 27 of spark to get optimal power due to the above forementioned information.

Mind you most of this discussion above is about octane limited fuels.

enjoy.

bigtymn

wow ls1 curious is on point normaly you achieve peak torque @ peak timing
and all the horse power is made with less timing heres anouther one for you
it takes more timing to burn less fuel and less timing to burn more fuel
so when you in pe mode and your @ 12 to 1 what timing do you run?

zmonsterjb

iTrader: (16)

I went from 26 to 28 and the car felt no different. THen from 28 to 24 and car woke up.

Slowhawk

iTrader: (12)

There is no garrenty that raising timing will give more hp.It needs to be tested on your setup.