[p4msi1]

What is a good total timing to run with E85 and 9.6 compression with 16 lbs boost. The motor is a 537ci and tiger heads.

Steve

[charlie66]

I dont think anyone here has any experience with boosting a tiger head . So i think you're going to have to tell us.. lol.

If it was me , i would find out what it wants N/A. My head made most power @ 34 degrees n/a. At 16 psi i have 26 degrees in it. So thats 8 degrees less. Start low and read your plugs. I think you would be safe a 20 dgrees and go up if the plugs say you can...

Personally i dont think timing is all equal from combo to combo. Anything anyone tells you is just a reference. There is a point of too low and of too high . I like it in the middle of that. Its a safe place . Fnding it is not that hard .Start low . You will most likely find good imptovment in power, but as you go further you will find the power is not adding up as much per degree . At that point i stop or go back a degree.

[p4msi1]

Thank Charlie I'm starting at 15 and will work up from there.

[charlie66]

N0 problem.

Be careful of low timing. It could burn up the tips of your turbine wheel...

Have you ever ran these heads N/A ?

[p4msi1]

Originally Posted by charlie66

N0 problem.

Be careful of low timing. It could burn up the tips of your turbine wheel...

Have you ever ran these heads N/A ?

In my signature............

I got rid of the nitrous and now have an F-2 Procharger. I made 1 hit on the dyno and a bad plug wire caused a big backfire which broke the balancer. It's too long of a story to type BUT it did make 737 RWHP in 1.26 seconds of the pull! Now that I got all the wires replaced and the motor runs clean it will soon be time to strap it down again. That was at 15* total timing and 16 lbs boost.

Steve

[charlie66]

That timing being so low concerns me . Dont get me wrong. Im not saying not to do it. I have no experience with tiger heads. It s just ive never seen timing needed to be ran so low before. Make sure the backfire has nothing to do with the low timing.

Did you put sleeves in the 3 outter exhaust head bolt holes in your tiger heads ?

[taff2]

Low ignition timing (retarded) can cause a pop back as Charlie said , it's best to have a boost adjustable timing box (MSD or built into an EFI ecu) so that you can run a fair bit of initial timing advance - 32/36 degrees or so-this will give you good throttle response and idle ,and then pull timing as boost increases. It's usual to start with pulling 1 degree per pound of boost and then add a degree back at a time, checking your plugs carefully. I would expect you to end up around 22-28 degrees total timing at 16 psi,maybe quite a bit more given your low compression ratio (for E85.)

[p4msi1]

Originally Posted by charlie66

That timing being so low concerns me . Dont get me wrong. Im not saying not to do it. I have no experience with tiger heads. It s just ive never seen timing needed to be ran so low before. Make sure the backfire has nothing to do with the low timing.

Did you put sleeves in the 3 outter exhaust head bolt holes in your tiger heads ?

I'm positive the backfire was ignition wires, 2 year old Taylors, cracked and arcing on the firewall intermittently

I put the sleeves on the center bolts only. I think I will do the outers next time apart..
15* is a starting point because I have no Idea where the boost will end up.

[p4msi1]

Originally Posted by taff2

Low ignition timing (retarded) can cause a pop back as Charlie said , it's best to have a boost adjustable timing box (MSD or built into an EFI ecu) so that you can run a fair bit of initial timing advance - 32/36 degrees or so-this will give you good throttle response and idle ,and then pull timing as boost increases. It's usual to start with pulling 1 degree per pound of boost and then add a degree back at a time, checking your plugs carefully. I would expect you to end up around 22-28 degrees total timing at 16 psi,maybe quite a bit more given your low compression ratio (for E85.)

I have an MSD Grid ignition with boost module so adjustments are easy. I'm hoping to bring the timing up to about 24-26 but won't know till back on the chassis dyno. So far it went to 16psi but I did not make a full pull yet.

Steve

[charlie66]

Originally Posted by p4msi1

I'm positive the backfire was ignition wires, 2 year old Taylors, cracked and arcing on the firewall intermittently

I put the sleeves on the center bolts only. I think I will do the outers next time apart..
15* is a starting point because I have no Idea where the boost will end up.

Ok i was just mentioning it because low timing will act that way..

At 38 psi im at 23-24 degrees . I use e85 like you ..

A friend of mine wanted to be conservative so he ran 10 degrees. He ran it like that for a few months. He burnt off 3/8" of his turbine wheel tips. shows how much heat goes into retarding the ignition. I realize your running a belt. But just sharing a learning experience with you... His is a 6 cyl 2jz . so his combustion chamber is different . But he went from 623rwhp to 740 rw going from 10 to 20 degrees..


Thats good . Yeah best bet is to do the outers as well. When i did mine there was a settling process. It needs to be re-torqued when its cold everytime until it stops moving. Might take a few times.. I dont believe in loosening to re-torque . I just set the wrench and pull on it. If it moves it moves ... Mine always did. Now they stay . No movement..

[p4msi1]

Charlie, funny you say that as I just checked the torque and 1 was loose and so far the driver side stayed tight but thanks for ANY input. I moved the timing up to 19 and tried it out on the street and boy did it get all over the road at about 60 MPH. I moved it back to 15 because I just don't want to hurt anything and these Tiger heads hated timing on nitrous.

[charlie66]

Lol. I bet its a beast.

Yes the bolts will loosen on there own time. Meaning randomly . They both will move the more you push on it heating up the heads. Just get out the torque wrench everytime before you start it when its cold. They will evenually stop moving. Also , even after they stop . They mostlikely will move again when you move up with the psi. It all make sense if you think about it..

In my opinion , at 15 degrees your motor is very restricted and not happy producing alot of heat that is unnecessary . Do you have a EGT gage hooked up?

I understand what you're saying about the nitrous. I feel the turbo pressure will effect it differently . Of course this is just my opinion. But i cant imagine those tigers not liking at least 20 degrees.

When you bumped the timing to 19 , did it feel like you freed the motor up?

What was your timing set to and how much did you take out at what shot /hp with the nos?

[p4msi1]

In my opinion , at 15 degrees your motor is very restricted and not happy producing alot of heat that is unnecessary . Do you have a EGT gage hooked up?

Tiger heads liked 15* on a 200 shot but compression was 12:1 and I was on C16 fuel. Now I am on E85 and 9.6:1 compression and am almost totally in the dark on what this motor will want for timing. The 2 fuels have different characteristics so I figured to start safe. If I had e-heads or iron heads maybe I'd start higher??? Even with 15* on nitrous I still torched the block and pass. side head and lifted ringlands. Strange thing is, I had local nitrous gurus inspect the plugs and they all said the tune was as good as it could be!

[p4msi1]

When you bumped the timing to 19 , did it feel like you freed the motor up?

Yes, Yes and did I mention Yes. LOL Here is the other reason I feel like I should start a little low on timing is because this C&S blow-thru carb has been a challenge to tune and I want to make sure the A/F is not lean as I move up the boost and RPM's. This whole combo is new and completely new to me so I have a learning curve and I don't want it to cast me custom pistons again. I plan to only make enough pulls to establish acceptable A/F then move timing up from there. I don't want to get ahead of myself chasing a big number......

[wreckmastr]

Just my but be careful running that low of timing as it will cause detonation which leads to a whole host of bottom end problems. I'm not sure what you plan on running for total boost in the end but I would say start out at 10 to 12 degrees below what your total is now as a starting point and read the plugs from there.

Completely different combo I know but my base timing is 36 degrees and at full boost of 45lbs it's at 27.5 degrees.

[charlie66]

Originally Posted by p4msi1

In my opinion , at 15 degrees your motor is very restricted and not happy producing alot of heat that is unnecessary . Do you have a EGT gage hooked up?

Tiger heads liked 15* on a 200 shot but compression was 12:1 and I was on C16 fuel. Now I am on E85 and 9.6:1 compression and am almost totally in the dark on what this motor will want for timing. The 2 fuels have different characteristics so I figured to start safe. If I had e-heads or iron heads maybe I'd start higher??? Even with 15* on nitrous I still torched the block and pass. side head and lifted ringlands. Strange thing is, I had local nitrous gurus inspect the plugs and they all said the tune was as good as it could be!

This is my opinion on that. Nitrous is much more violent then adding just pressured air from a turbo.
C16 burns at a different rate then e85.E85 also burns cooler. Change those 3 facts you have a whole new stuation. So maybe it wont be as bad as you think?

Just the fact that you can say bumping the timing only 4 degrees really freed up the motor is telling you that you're heading in the right direction.. Follow the signs . 15 degrees of total timing is very low.. Scary low in my opinion. A 200 shot is more destructive then 15 psi in my opinion. A 200 shot on a bench test sends a manifold flying up off the bench ! lol. Dont mind me im just thinking out loud here !

One real imoprtant thing here is to stay on top of those head bolts. If they losen it will blow the gasket maybe even torch the head. Most guys torque the head once, maybe 1 other time. Thats a big mistake when you have boost involved . I have a probe in every primary tube. So i know what happens lifting on and off the throttle. One lift of the throttle the EGT's will drop 1000-1400 degrees in a millisecond. It use to blow my mind watching it. How many times do we throttle are cars. lol. So imagine the hot and cold effect is having on the aluminum . It starts to anneal it to the point of no good. So now the bolt towers start to sink from the meterial not being capable of handling the clamp load of the fastener , which in turn blows the head gasket or even worse in some cases .

Sorry , Ive just been through it . Only trying to share what i had to learn the hard way ...

[p4msi1]

Originally Posted by wreckmastr

Just my but be careful running that low of timing as it will cause detonation which leads to a whole host of bottom end problems. I'm not sure what you plan on running for total boost in the end but I would say start out at 10 to 12 degrees below what your total is now as a starting point and read the plugs from there.

Completely different combo I know but my base timing is 36 degrees and at full boost of 45lbs it's at 27.5 degrees.

Thanks Billy,

aren't you running straight alcohol?

[p4msi1]

Just the fact that you can say bumping the timing only 4 degrees really freed up the motor is telling you that you're heading in the right direction.. Follow the signs . 15 degrees of total timing is very low.. Scary low in my opinion. A 200 shot is more destructive then 15 psi in my opinion. A 200 shot on a bench test sends a manifold flying up off the bench ! lol. Dont mind me im just thinking out loud here !

Makes total sense so I will keep it at 19 because it did like that! I know it is running slightly lean at 8.4 on the E85 scale, so I need to put a little more jet in it.

Man, you guys have been so helpful!!!!!!!!!!!!!!!!!!!

Steve

[charlie66]

What i do when im not sure is set the car in second gear rolling at around 20 mph throttle it down to the floor till around 4500 to 5000 rpm watching the a/f gage or if you can log it. Once you know you're good with your a/f then move on to more rpms till your all good recahing your shift point. Then do the same in third. Point is most people burn there engine up because they commit to a full run prematurely . Quick hits in second checking your a/f just gets you to a place where you can have a little reassurance its ok to test your motor all out. Third is the high load gear that usually burns things up.. I would be shooting for .80 lambda which is 11.8 a/f... heres a good link you should refure to ...

http://www.partssa.com/downloads/204...fuel+ratio.pdf

[charlie66]

One of the hardest parts about tuning a boosted street engine for me was getting the transitioning right from vacuum to positive pressure . Its mostly in the spring / pvcr's man...