What ignition advance do you run?

[180bfj20det]

Just interested to know what ignition advance you guys run at full rpmand full boost. Please include your engine, compression ratio, rpmand boost level for ignition timing.

Mines 11 degrees at full song and my compression ratio is 9.1:1.

Ive tried posting a few times but hasnt worked so hopefully it does this time.

Cheers

[gtst25]

Gidday,

This is the graph dad and I made from my apexi power fc hand controller.

It's just a stocko rb25, stock compression ratio.

Full boost of 14 psi is about from load points 11 to 15/16.

Cheers

[180bfj20det]

Bump

[MattSR]

What turbo, engine, RPM, cam profile are you running to get those figures?

I cant really contribute as I only have a stock VTEC Civic

[RB30-POWER]

11deg isn't much timing at all.

But i suppose when you have big turbo's and pump fuel, you have to compromise somewhere.

[180bfj20det]

11deg isn't much timing at all.

But i suppose when you have big turbo's and pump fuel, you have to compromise somewhere.

Yeah its not much timing but we couldnt throw anymore in without it pinging. How much more power do you guys reckon I could make if I dropped my compression to 8:1 rather than the 9.1:1 I run now? How much more timing could I chuck in?

[RB30-POWER]

I take it your running an NA bottom end? FJ20E?

What comp ratio does the FJ20ET run from factory?

With these older motors and their combustion chamber design, its always difficult to make lots of outright power especially with higher compression ratios than standard.

My guess would be if you dropped the comp ratio, down to 7.8:1 or therabouts you could make significantly more power on pump fuel.

However the off boost drivability would suffer a bit.

I don't really know for sure if lowering the comp ratio will allow you to run that much extra timing to gain big results. I would be fairly sure you could make a fair bit more power by running more boost, however this doesn't really help your timing issue, which i think you want more off.

I guess what im trying to say is that if you lower the comp ratio you would be able to make more power with extra boost rather than timing alone, however, more timing would be better for the motor and im sure their would be significant response and torque gains with the addition of extra timing rather than boost.

I can say for a fact that alot of the calaisturbo guys with VL's that run GT35/40 and such with turbo bottom ends 7.8:1, can usually only run around 10- 15deg at full song on pump fuel at up to 20psi. Once again this is due to the design of the 2 valve per cylinder head which is quite old now and doesn't have great "squish" areas.

Another thing i may add, is getting the correct bump sticks (cam) for your motor can have a fairly big impact on the timing you can run. Especially when your talking big boost on pump fuel.

Either way, i think your got preety good power from your setup, so if your happy with it i would be weary about pursuing other mods just to get that little extra bit from it, which will cost big $ and give average results, for the $ spent.

[Sydneykid]

We are running around 16 degrees at 420+rwkw out of an RB31DET at 1.3 bar with a compression ratio of 9 to 1. That's at 6,900 rpm, at 7,500 rpm the ignition timing is up to 22 degrees.

By dropping the compression ratio and increasing the boost you make make more max power, but the average power will be much the same and you will loose a lot of response. An alternative would be camshafts with more overlap.

My guess is you have an inlet temperature problem that is adding to the pre-ignition. If you are running a plumb back BOV, then it could be oil contributing.

[33SOM]

um... my fc shows 42degrees at about 4000rpm!!??? is this bad??

Engine is a rb25 with lowered comp and stock turbo. Power FC is still untuned.

Car also has a overheating problem could this have something to do with it??

[jazza08]

I dun think thats ignition timing... lol

I was told 15 degrees on a lightly modified rb20 will help bring responce up and is still within the safe limits.

[180bfj20det]

We are running around 16 degrees at 420+rwkw out of an RB31DET at 1.3 bar with a compression ratio of 9 to 1.  That's at 6,900 rpm, at 7,500 rpm the ignition timing is up to 22 degrees.

By dropping the compression ratio and increasing the boost you make make more max power, but the average power will be much the same and you will loose a lot of response.  An alternative would be camshafts with more overlap.

My guess is you have an inlet temperature problem that is adding to the pre-ignition.  If you are running a plumb back BOV, then it could be oil contributing.

Thanks for your response guys.

RB30: you are absolutely right in saying that I will have to spend big dollars to gain just a bit more power. The again, the standard FJ20ET makes 340-350hp in standard form from 18psi so there must be something there...the standard FJ20ET has a compression ratio of 7.5:1 or 8:1 and the only difference bt NA and turbo is compression ration and cam timing the latter which I have modified to turbo specs.

Yes, my engine is a totally stock FJ20E!!!!!!! Unbeleivable it handles this boost and power but then again these are strong engines.

SYDNEY KID:

I am envisaging the use of large duration camshafts the drop static compression ratio so I can add more timing. I have been recommended to use 280-288degree cams which I would love to do cause Idont give two shits about drivability I just want a fast car...that said power delivery is important for making a fast car but then again these are tomei cams and I suppose they are designed properly.

I have a venting BOV so no problem with oil. Also, inlet temp is never over 40degrees usually in the 30s.

I just wanna make more power pump...

Can you explain how bigger cams lowers static compression ratio? Also if it lowers static compression ratio, wont it raise effective compression ratio (ie when on boost and revs)? I know the answer to the last question is no but could you explain it...you can talk cam timing as I understand this a little bit.

Thanks

[33SOM]

I dun think thats ignition timing... lol

I was told 15 degrees on a lightly modified rb20 will help bring responce up and is still within the safe limits.

Umm yes it is. I can show u a pic if u want.

I think my crank angle sensor is incorrectly installed cause the little guide thingie were it sits in was broken and im not 100% itslined up correctly.

Make sense??

[gtst25]

Gidday,

This is the graph dad and I made from my apexi power fc hand controller.

It's just a stocko rb25, stock compression ratio.

Full boost of 14 psi is about from load points 11 to 15/16.

Cheers

Sorry about that - couldn't get the spreadsheat to upload - it's only about 11kb but we did it in microsoft excell.

Bit of a hard one to say really without showing the graph - depends on the revs but at full boost at the moment it's about 18 - 20 degrees.

[Jolinator]

rb20det manual hcr32 runs 15 degrees stock jazza08 - 20degrees on the auto

[ace_nz]

40 degrees at 4000 revs and light load is normal, lean cruise mixtures burn slowly so you need lots of advance, it helps fuel economy heaps, like vacumme advance on a carb.

[Sydneykid]

SYDNEY KID:

I am envisaging the use of large duration camshafts the drop static compression ratio so I can add more timing. I have been recommended to use 280-288degree cams which I would love to do cause Idont give two shits about drivability I just want a fast car...that said power delivery is important for making a fast car but then again these are tomei cams and I suppose they are designed properly.

I have a venting BOV so no problem with oil. Also, inlet temp is never over 40degrees usually in the 30s.

I just wanna make more power pump...

Can you explain how bigger cams lowers static compression ratio? Also if it lowers static compression ratio, wont it raise effective compression ratio (ie when on boost and revs)? I know the answer to the last question is no but could you explain it...you can talk cam timing as I understand this a little bit.

Thanks

Camshaft timing and lift are restrictions to airflow and boost is simply a measure of restriction. So by increasing the duration and lift, you will lower the boost

The amount of overlap determins how much compression "escapes" before both inlet and exhaust valves are closed. At lower rpm's this can be significant, at higher rpm, not so, as there is less time for the escape.

Tomei have no idea what gearbox ratios you are running and that is usually the determining factor in how much camshaft overlap you can run and still stay in the power band on upchanges. Cams with 288 degrees of duration will usually need a close ratio gearbox to be usefull.

The old FJ is a tough engine, but they are quite restrictive, so its a vicsious circle. They need boost to overcome the restrictions and make decent power and they are tough enough to take it. But if you remove the restrictions, then you don't have to run the rediculously high boost. Personally I would much rather make 500 bhp at 1 bar then 500 bhp at 2 bar, but some people find the bragging rights of 2 bar important. To me running 2 bar (when 1 bar will do the job) is simply a sign of poor restrirction removal.

So if you haven't already done it, get into the ports and combustion chambers, the inlet manifold, the exhaust etc . If you have a standard ratio gearbox then I wouldn't go over 272 degrees.

Hope that makes sense:cheers:

[180bfj20det]

The FJ20 head is actually a very free flowing head. I have heard of people porting it and making losses due to the air velocity being reduced. Mic sheringham's gemini makes over 520rwhp with standard head (completely standard: ie cams, valve timing, ports, etc...). This is the greatness of the FJ20 head. But for me compression is a problem and there is no doubt large duration cams will help with this though like you said I will probably need a closer ratio gearbox. I will see what happens and keep everyone posted when I fit 280degree cams.

Another thing:

My compression ratio is 9.1:1. My FJ makes 307rwhp. FJs with compression ratios of 8:1 make 350rwhp. The difference is timing: mine has 11degrees advance on full song while the 8:1 fjs have up to 18 degrees. So the 8:1 has up to 7 degrees more advance...Do you guys think this extra 7 degrees would take my 307 to 350rwhp if I were to drop my compression ratio to 8:1? Also is it bad to use a thicker head gasket to do this and if not, are the copper ones OK?

Cheers

[RS500]

Camshaft timing and lift are restrictions to airflow and boost is simply a measure of restriction.  So by increasing the duration and lift, you will lower the boost

The amount of overlap determins how much compression "escapes" before both inlet and exhaust valves are closed.  At lower rpm's this can be significant, at higher rpm, not so, as there is less time for the escape.

The old FJ is a tough engine, but they are quite restrictive, so its a vicsious circle.  They need boost to overcome the restrictions and make decent power and they are tough enough to take it.  But if you remove the restrictions, then you don't have to run the rediculously high boost.  Personally I would much rather make 500 bhp at 1 bar then 500 bhp at 2 bar, but some people find the bragging rights of 2 bar important.  To me running 2 bar (when 1 bar will do the job) is simply a sign of poor restrirction removal.

hi SK,

i have a question regarding your response above given that you've had experience with engines like mine, what are your thoughts on the YBD Sierra Cosworth engines?

the reason i ask is b/c i am looking installing different spec cams in my engine in the near future, as to gain more power/torque in the mid-high rpm range with less/same boost.

also, i would like to know what your recommendations are regarding cam specs for my engine (street & soon circuit/track car).

thanks in advance.

[RS500]

The FJ20 head is actually a very free flowing head. I have heard of people porting it and making losses due to the air velocity being reduced. Mic sheringham's gemini makes over 520rwhp with standard head (completely standard: ie cams, valve timing,  ports, etc...). This is the greatness of the FJ20 head. But for me compression is a problem and there is no doubt large duration cams will help with this though like you said I will probably need a closer ratio gearbox. I will see what happens and keep everyone posted when I fit 280degree cams.

Another thing:

My compression ratio is 9.1:1. My FJ makes 307rwhp. FJs with compression ratios of 8:1 make 350rwhp. The difference is timing: mine has 11degrees advance on full song while the 8:1 fjs have up to 18 degrees. So the 8:1 has up to 7 degrees more advance...Do you guys think this extra 7 degrees would take my 307 to 350rwhp if I were to drop my compression ratio to 8:1? Also is it bad to use a thicker head gasket to do this and if not, are the copper ones OK?

Cheers

hey there dude,

regarding your engine, CR, timing etc, running higher compression is obviously better as it brings better turbo & engine response which makes the car feel better to drive down low.

why don't u keep the engine as it is, and run higher octane fuel (i.e., elf turbo max). this will allow you to have the best of both worlds, a high compression engine, running high boost and more ignition timing advance.

if i ever rebuild my engine again, i'll definitely go this way, but then again i have forgies ;-)

Also, how do u find the GT30R with A/R .82 exhaust housing, does it feel laggy/doughy?

[Sydneykid]

The FJ20 head is actually a very free flowing head. I have heard of people porting it and making losses due to the air velocity being reduced. Mic sheringham's gemini makes over 520rwhp with standard head (completely standard: ie cams, valve timing,  ports, etc...). This is the greatness of the FJ20 head. But for me compression is a problem and there is no doubt large duration cams will help with this though like you said I will probably need a closer ratio gearbox. I will see what happens and keep everyone posted when I fit 280degree cams.

Another thing:

My compression ratio is 9.1:1. My FJ makes 307rwhp. FJs with compression ratios of 8:1 make 350rwhp. The difference is timing: mine has 11degrees advance on full song while the 8:1 fjs have up to 18 degrees. So the 8:1 has up to 7 degrees more advance...Do you guys think this extra 7 degrees would take my 307 to 350rwhp if I were to drop my compression ratio to 8:1? Also is it bad to use a thicker head gasket to do this and if not, are the copper ones OK?

Cheers

My 20 cents worth.............

Maximum power at one rpm point is a useless measure of an engines efficiency. Based on our useage over the years , the standard FJ20 head is far from "free flowing". The flow bench is the test and they were good, 20 YEARs AGO, but time has passed them by. The air velocity is only reduced when you don't achieve the airflow (horsepower) that the port is designed for. It is pretty stupid to machine a port for 60 lbs of airflow per minute and then use a 30 lbs per minute turbo. You will never generate enough boost to overcome the other restictions.

You are getting far to hung up on compression ratio, I have seen 1100 bhp out of an RB with 9.3 to 1. It is not limiting your average power output.

Yes it is bad to use to a thick head gasket, I have seen detonation increase when thick headgaskets have been used to lower compresion ratios. They make a nice sharp edged firing ring all the way around the combustion chamber. They also remove what little squish the cylinder head has. It is FAR superior solution to machine the combustion chamber for increased volume and then polish it for further decrease in hot spot detonation.

But if you lower the compression ratio then you can expect a noticeable decrease in response. But you might be able to brag about a higher max power, but it will make the car slower, maybe that isn't your aim.