What ignition advance do you run?

[Cubes]

Red_Drifter,

How is fuel economy with that base map?

[RedDrifter]

Red_Drifter,

How is fuel economy with that base map?

Its hard to say really. I am using bigger injectors now and I get a little less economy but I do have a bit of a led foot though.

[pnblight]

i run about 22deg at about 4500rpm at full boost

to about 27deg at about 8000rpm at full boost

gtr rb26dett

garret GT2560R turbos

APEXI pfc and avcr

tomei 260deg 9.15mm cams

700cc injectors

z32 afms

529.4rwhp 20psi

and personally i think your looking in the wrong areas even tho the timing your running is very low, i would be interested what a/f ratio your running at full boost and are you using bp ultimate or a different 98 ron.

pete

[Cubes]

A restrictive hotside reduces VE & ignition timing.

Reversion.

One reason why I am only able to run only 15degree's with the stock rb20 turbo running only 9psi. Huge back pressure.

[MattSR]

Also limits the size of the cams your motor will tolerate....

I agree totally - backpressure is GAY....

I have seen a stock S2000 motor run 6psi boost through a HKS GT3040 - made 240rwkw and run heaps of timing all on 11:1 compression.. The reason why was because of the low backpressure and big overlap of the VTEC high cam...

Cheers,

Matt

[yogi000]

Hey Everyone.....this might seem strange.....but anyone had a problem with knock going sky high when jumping off the throttle and in some case jumping straight on it (i.e. Deceleration).

I can run thru all the gears.......WOT and might get knock of 35-40 but then if i hesitage half way thru 3rd it will gimme a knock of 60+. I jump off the throttle immediately to avoid causing something bad.

Any idea and maybe a solution which i can do via hand controller?

Thanks

George

[Cubes]

I had a similiar issue.

It didn't have any issues coming off the throttle when at peak power but more so if I gave second a full run then half of third and came off the throttle.

If I didn't come off the throttle quick enough it would get a knock of 40 odd.

I checked the load points used when coming off the throttle slower and had a fiddle.

I observed that part of the map that was used when coming off the throttle had not been modified, from memory the origional pattern was that load points 15-17 ran 2 degree's more than load points 18-20.

So I changed load points 15-17 to represent that.

Mine came down to lack of time on the dyno, just a rough tune.

I got what I asked and paid for. $100.

I gave it a run and no more knock. It now never goes over 18.

I find the load points I modified almost never get used apart from when coming off the throttle.

Check what load points WOT uses. Mine hangs around 19 and some times dips to 20. The origional map has 18-20 use the same ignition timing, mine didn't have this and would also cause the odd highish knock reading when occasionally it used to hit it due to different air temperatures.

I changed 18-20 to read the same, no more knock under that circumstance.

Also, with regards to light load ignition timing. Don't be fooled in to thinking more is better. The iginition timing has to be set correctly so that peak pressure is achieved roughly 10degree's after top dead center.

As the load increases the charge becomes denser, a denser charge burns quicker which is why you don't require as much ignition timing i.e 45degrees vs 30degree's.

So by simply slapping 45degree's over the complete light load map as the 32 GTR map has basically done it is far from optimal. Optimal being receiving the best torque from what air and fuel is in the cylinder.

All I need to understand now is how the longer stroke (hence faster piston speed) affects the ignition timing setup.

Since using the RB25DET light load map I have actually picked up some economy it seems. 3/4 of a tank and i've just nudged 360km's so its looking a little better so far.

Its a pitty I didn't change the map at the start of the tank, when I made the changes I had already used 1/4 of a tank and done 101km's.

[180bfj20det]

i run about 22deg at about 4500rpm at full boost

to about     27deg at about 8000rpm at full boost

gtr rb26dett

garret GT2560R turbos

APEXI pfc and avcr

tomei 260deg 9.15mm cams

700cc injectors  

z32 afms

529.4rwhp 20psi

and personally i think your looking in the wrong areas even tho the timing your running is very low, i would be interested what a/f ratio your running at full boost and are you using bp ultimate or a different 98 ron.

pete

Im running an AF ratio of 11.5-11.7 at full boost. Also I use BP ultimate as fuel. GTRs can handle more timing because they rev better creating less reversion. Hondas can be turbocharged and run big boost and ignition because they have large cams with large overlap.

I definately am convinced my compression ratio is the problem to not making 350rwhp. Like I said, my buddy has the FJ20ET (as opposed to my FJ20E ie Natural), runs 16-18 degrees of timing and makes only slightly less power than I except I run a GT30R and he a first generation plain bearing s14 t28!!! Im just gonna get a FJ20ET and make the power I want that way...because you're right, maybe ign isnt just the reason to my dilemma and other intrinsic differences may exist bt the 2 engines responsible for the power difference. I cant be stuffed (ie dont have the money) trying to figure it out...so the FJ20ET is the go.

Does anyone have a good link to why methanol is a better fuel than pump. I have read that it's energy content is its most important aspect rather than its octane content which is not huge (ie 102 or something like that). I also know that methanol absorbs a lot of latent heat during transition from its fluid to gas state favouring lower temperatures.

Cheers

[Cubes]

180B,

Have you thought about valve springs causing a problem?

N/A Valve springs by nature have less tension, Turbo springs require more tension as they have to hold against both the pressure of the turbo and the back pressure from the turbo.

Weak valve springs will cause a flat top end and detonation.

[180bfj20det]

180B,

Have you thought about valve springs causing a problem?

N/A Valve springs by nature have less tension, Turbo springs require more tension as they have to hold against both the pressure of the turbo and the back pressure from the turbo.

Weak valve springs will cause a flat top end and detonation.

From what you say I assume that valve springs with weaker tension will therefore "leak" boost away and not effectively vent away exhaust gases due to exhaust back pressure...am I correct? If not please explain a bit more the reasoning behind weak valve springs and boost (though it makes sense, Id rather here it from someone who knows rather than making an educated guess). How would it cause detonation...it is because residual exhaust gases dilutes incoming air?

Thanks a lot for your help, I appreciate it HUGELY!

[180bfj20det]

11.7 should be fine i run around 11.9 to just under 12 in my gtr at 20 psi at 530rwhp(397rwkw) and up 27 deg adv timing

I had to quote this from another thread. Awesome power, expected AF ratios and look at that timing!!!! woo hoo!!!!!!!!!

Good stuff pnblight

[Cubes]

Its simply valve bounce.

Like having a cam that never totally closes the valves. Reversion occurs, and VE suffers.

If its bad enough and the exh. valves get hot enough they will overheat and drop off.

You need good seat pressure in order to remove the heat from the exhaust valves.

[RB30-POWER]

Which brings us to GTR exhaust valves....

Sodium filled, YUM

[RS500]

Which brings us to GTR exhaust valves....

Sodium filled, YUM

same as the ford sierra cosworth :headspin:

[MattSR]

Sodium filled valves are shit compared to one piece stainless Inconel or titanium valves..

[Sydneykid]

Sodium filled valves are shit compared to one piece stainless Inconel or titanium valves..

Titanium valves work harden so we have to change them after ~1000k's. Not a good idea in a raod car.

[benl1981]

Old thread - but on the same sort of trend.

Rb25 running GCG turbo. Been getting some knock - though not very consistent.

18psi (tailing to 16psi). Made 247rwkw. Was getting readings of 90-100 knock around 5000rpm - 6000rpm under full throttle. Pulled 2 degrees out of most of those cells. These were load point 16 (using z32 afm).

Most of those around around 15 deg advance now.

Just lately noticed some knock around 4000rpm in 3rd and sometimes 2nd. I've pulled out about 3 deg around that zone. When it's at 3500-3700prm it's at load point 16 so I've only altered load point 15 and 16 around that zone. I've also pulled 1 deg out of a few cells close by in case it's passing through there.

Thing was it wasn't pinging on the dyno. Don't know if it's just mechanical noise or what. Thought it might be a bad batch of petrol but it's been on 2 tanks now, and it has always had the tendancy to flash the check engine light (knock oer 60) every now and then (not consistently).

Can somebody post their ign map with similar mods - would like to see if mine was a bit agressive. Around 5000rpm it had about 16 deg previously going up to 20 deg at 6800rpm.

Dyno was done in summer about 27 deg, would think now being cooler would not be an issue at all..

All ignition no.'s in the attached are before touching the tune myself, the negatives are the corrections I have made (I have made more since), to bring a lot of load point 16 no's back to ignition advance values of 14 or 15..

Ignition_map.pdf

Edited July 10, 2008 by benl1981

[08yannch]

i have my R33 GTS-T set to 13 it was at 15 from the factory

i changed it because of some ignition problems

i might change it to 11 in the future we will see how 13 goes

[CEF11E]

just some more info on ignition maps

rb30det running 18 psi 270rwkw and a reasonable amount of back pressure 8.3:1 compression ratio with stock rb25 non turbo head

20deg advance at full boost of 2800rpm. peaking at 21deg at 6800rpm. power is a perfect bell curve and the is no detectable knock.