General Attention High Compression E85 Users-Ignition timing questions

[Kapok6]

Attention High Compression E85 users. I need some input and advice here. I'll start off by saying I know that every motor is different even if they are the same or similar on paper.
So, what I am trying to figure out is, how you guys tune your high comp motors on e85...specifically what your timing maps look like.

Up to this point I have been an 8.3-8.5 compression guy with HKS 272's.

Now, I have a Curt Brown block and head (2G) with GSC S2's. Pistons are 10.5:1. DSM76 HTA turbo.

So, I have spent the last few weeks trying to tune out "knock" based on my knock sensor readings. AFRs are high 11's to about 12.0. I have pulled ignition timing WAY back. That seemed to help get most of it gone. I had to pull timing down to 0* at 5500-6500 (guessing that is peak torque area) to get it nearly completely gone. There would still be an occasional blip here or there with 1ct or so and the ecu will pull timing to -1*, and occasionally it will show knock in the middle of a shift as the rpms are dropping. So, shifting from 1-2 or 2-3 as the rpms fall from 8700 to 6300, it will register knock in that area.

So right now, I am at 0* 5500-6500, then ramping up from there to about 7-8* up top around 8500-9000. IMO previous experience, that is NOT a lot of timing at all. And I know a lot of the high HP Honda guys run negative timing on their high efficiency motors, but does this sound right?

I know generally speaking, high comp motors, (or boosted motors in general) like more boost, less timing, but honestly at this point the car is slow as bawlz compared to what it was on my previous hodge podge motor. Best trap I have got it to do in the 1/8 so far is 97.8 which is laughable compared to the 101 I got on my old lower comp motor and less boost with the same turbo.

So with all that rambling done, what kind of ignition timing are you guys running on your high comp e85 motors? I think one of my problems may be going off the stock knock sensor as my understanding is that with E85, you will blow a HG or bend a rod before you actually register real knock...

 

[1990TSIAWDTALON]

I have a 10:1 motor on E85 (that is more like E65),36lbs of boost, and I run about 9* at 3500 and ramp up to 16-18 at 8300. I have ADDED 1-2 degrees at the top after 6500 as it was just 15*. I think 7-8* is very low IMO, but you have to make sure that knock is missing. I don't see even 1* of knock at 8300. This, like you said, is a different beast but your timing seems low and you can tell it in the seat I bet. Are you sure your knock sensor is reading correctly and not going out on you? Is your E85 good quality?

 

[Silent_White]

what plugs/ gap?

 

[1990TSIAWDTALON]

Currently BR7ES's. I will be trying BR8ES's soon, but no problems with the 7's. I am at .028 on the gap and run a ARCII box.

 

[Kapok6]

I have ran 8's and 9's. No difference. Gapped to .018. Any bigger and I get spark blow out even with my arc-2. Knock sensor is brand new.

And I don't typically see the knock above 7000rpm's.

 

[Stew Pidaso]

All of my mods are up to date in my build thread. I see about 13-14* around peak torque and then ramp up to 21* from 6k on. I haven't tried dipping lower coming into torque yet but would like to at some point. I really don't knock throughout any of my pulls either. Maybe .4 or .7 for a split second but besides that it pulls pretty good. I'm also running BR8EIX plugs gapped to .020"

 

[xxNocturnalxx]

I have my CEL set to turn on at 3* knock and I don't believe it's ever come on sense I made the switch to e85. I am stock block and head but run about 20* timing up top with peak boost at 30psi. BR7ES .025.

 

[Kapok6]

Yeah, I never had an issue on my lower comp motor and 30-35psi in the upper teens on timing up top.

 

[Marchev]

I would be very skeptical to run it at such low timing, you may start burning exhaust valves very quick. First I would check that the knock sensor is torqued properly, and then I would up timing to low teens, and drop the afrs. I've had to run as low as low 10s afr in hot weather here in order to keep knock in check. I can only get E70 in my area btw. What are your IATs at?

 

[Stew Pidaso]

Post a log so we can check things out. What altitude and outside temps are you working with?

 

[Kapok6]

I would be very skeptical to run it at such low timing, you may start burning exhaust valves very quick. First I would check that the knock sensor is torqued properly, and then I would up timing to low teens, and drop the afrs. I've had to run as low as low 10s afr in hot weather here in order to keep knock in check. I can only get E70 in my area btw. What are your IATs at?

Knock sensor is 17ftlbs per factory spec. The problem is, if I up the timing, it detects knock and pulls timing. IAT's 105-115 usually depending on the temp outseid when I do a pull.

Post a log so we can check things out. What altitude and outside temps are you working with?

Altitude is whatever regular altitude is. I'm not up in the mountains or anything. I don't have a log to post. I did the pulls, reviewed the graphs, and at got rid of them. Outside temps have been in the 80's. IAT's 105-114 depending on the day and how hard of a pull i'm doing.

 

[Marchev]

Knock sensor is 17ftlbs per factory spec. The problem is, if I up the timing, it detects knock and pulls timing. IAT's 105-115 usually depending on the temp outseid when I do a pull.

I understand if you up the timing, without changing anything else, you will knock. What I was saying is lower your AFRs to like 10.5 and THEN start upping the timing to see how much you can get away with. Depending on the quality of your e85 you might have to run richer. You'll still make good power on richer mixture and higher timing

 

[boostdawd]

If he drops his afr that low I'm sure he will get rich knock.

 

[donniekak]

If he drops his afr that low I'm sure he will get rich knock.

My car pulled smooth from 10:1-12:1 on e85 at 35+ psi of boost and 70lbs/min. It's worth trying to see what the car likes.

 

[biglady112]

Easy answer and how I set up every car. Pull the knock sensor out, fill the hole with RTV, apply a small amount of RTV to the outside, flat part of the hole boss and tighten the knock sensor back down.

The only other suggestion I have is move the knock sensor away from the stock location (if you have a turbo block that is ) and try the hole at the top of the cylinder behind cylinder #2. Having noise from two cylinders hammering the knock sensor helps no one. The stock Mitsubishi knock system is so primitve it won't do you any good and you will lose the motor even if things are right. More data is the key there. Not everyone can afford a real datalogging system however that monitors much more stuff.

High compression motors are bad, mmkay? It seems you are finding that out too late. As you have seen your tuning window has decreased quite a bit.

Move the knock sensor, cushion it with rtv and add some fuel back in it. Shoot for 11.0:1. You won't be losing anything by doing so but, will be cooling the cylinders more, helping your cause.

This is 18 years of experience speaking here. Trying to keep an 800hp 4g63 together for five miles wide open down the Bonneville Salt Flats will teach you a lot of things. It will mean a lot I broken parts but, you will learn of you stick with it.

As Donnie stated above, don't be afraid to try mid 10's even. If it is pulling clean a little fuel never hurt anyone. Not going to hurt a motor by running rich. And get colder plugs. Your cylinder temperatures will thank you.

 

[bastarddsm]

What are the plugs showing??

As for AFR's, back when I had a cx racing junk fmic and 200*+ IAT, It didn't seem to have any issues with rich knock, but it was faster super rich. (chemical intercooling) Now that I'm back on a good fmic with ambient AIT, it definatly shows rich knock if I'm down in the low 11's. AFR.

 

[Kapok6]

My car pulled smooth from 10:1-12:1 on e85 at 35+ psi of boost and 70lbs/min. It's worth trying to see what the car likes.

I'll try lowering it a point or so and see if that does anything.

Easy answer and how I set up every car. Pull the knock sensor out, fill the hole with RTV, apply a small amount of RTV to the outside, flat part of the hole boss and tighten the knock sensor back down.

The only other suggestion I have is move the knock sensor away from the stock location (if you have a turbo block that is ) and try the hole at the top of the cylinder behind cylinder #2. Having noise from two cylinders hammering the knock sensor helps no one. The stock Mitsubishi knock system is so primitve it won't do you any good and you will lose the motor even if things are right. More data is the key there. Not everyone can afford a real datalogging system however that monitors much more stuff.


High compression motors are bad, mmkay? It seems you are finding that out too late. As you have seen your tuning window has decreased quite a bit.

Move the knock sensor, cushion it with rtv and add some fuel back in it. Shoot for 11.0:1. You won't be losing anything by doing so but, will be cooling the cylinders more, helping your cause.

This is 18 years of experience speaking here. Trying to keep an 800hp 4g63 together for five miles wide open down the Bonneville Salt Flats will teach you a lot of things. It will mean a lot I broken parts but, you will learn of you stick with it.

As Donnie stated above, don't be afraid to try mid 10's even. If it is pulling clean a little fuel never hurt anyone. Not going to hurt a motor by running rich. And get colder plugs. Your cylinder temperatures will thank you.

I'll try the knock sensor trick(s) mentioned above.

"High compression motors are bad, mmkay?" Not entirely sure weather that is a question or a statement, but since there is a "?" at the end, i'll respond as such. I don't recall ever saying high comp motors were bad. It's simply a learning experience.

I'll try richening it up a point or so and see if that changes anything.

What are the plugs showing??

As for AFR's, back when I had a cx racing junk fmic and 200*+ IAT, It didn't seem to have any issues with rich knock, but it was faster super rich. (chemical intercooling) Now that I'm back on a good fmic with ambient AIT, it definatly shows rich knock if I'm down in the low 11's. AFR.

When I switched out the 8's out for 9's, I didn't notice and speckling. Outside of that, I am still a noob at reading plugs. I have a Precision IC. IAT's on a pull typically 105f-115f. I'm sure it would go higher if I were to do a top end pull in 3rd. These temps are based on a pull all the way through 2nd and into 3rd.


Thanks for everyone's inputs.

 

[biglady112]

That is a statement. The 4g63 is horribly inefficient. It does not have the broadest spectrum for tuning. Its saving grace is its iron block. And by adding more cylinder pressure from the get go (static compression), you have taken a small window and made it even smaller. That is why I said you are finding it out too late.

 

[Vegas Smith]

That is a statement. The 4g63 is horribly inefficient. It does not have the broadest spectrum for tuning. Its saving grace is its iron block. And by adding more cylinder pressure from the get go (static compression), you have taken a small window and made it even smaller. That is why I said you are finding it out too late.

What CR would you recommend for mild-medium hp e85 cars such as OPs? ( gets out pen)

 

[donniekak]

What CR would you recommend for mild-medium hp e85 cars such as OPs? ( gets out pen)

I personally don't like to go over 9:1. Unless it's a car trying to set a class record it's not worth the possible 20-30hp increase on a high power car to go through the headaches getting a high cr setup running at peak performance.

Kiggly picked up power and spool going back to a lower cr setup.

 

[bastarddsm]

^ 100%. Lower compression increases VE when your intake pressure is higher than exhaust pressure.

Kapok,
back a couple years ago when I was pushing the Hy35 very hard I was up in the 21-22* of timing area at 35psi+ It would constantly have a few blips of knock here and there. I turned off the knock sensor and let it eat. It would show up some light pepper on the plugs (signs of det), but the car was fastest like this, I had great life out of cheap felpros, and the bearings looked perfect when I took it apart.

the "pepper" your looking for is very very small spots of black on the insulator. You'll need a magnifying glass if your eyesight isn't good. The plug needs to be new as well, by the time it has one or two passes on it, there's too much buildup. The idea is that when it knocks it shocks the rings and bits of oil splash up and land on the plug, and get fused there.

It's a bit of an art, and not very exact. the pepper could just be bit of oil from the turbo leaking a bit or who knows. The KS is overly conservative on a stock engine, and who knows on a high power deal. It might be knocking lightly, but more timing might not hurt it, and make more power.

Remember detonation is just very very fast combustion. The faster the combustion the more efficient the engine is. I've read several papers talking about running the engine in detonation to get high efficiency. It's all about how much cyl pressure your engine can tolerate.


This is why I like the felpro, do whatever I want and it pretty much tells me if it likes it. It either goes faster or it pops a HG. Although, I've never actually put a gasket out from the tune-up. I guess I don't get aggressive enough.

 

[Kapok6]

When I had the motor built and asked what comp ratio was recommended as up to this point I have been an 8.3-8.5 kind of guy, the builder stated he liked high comp. 11:1ish. He also stated he made 600awhp on 93oct with no training wheels. I have NO doubt it happened. I am just trying to learn this whole high comp thing.

As for Kiggly, yeah, I read his statement that he didn't really see any benefits over 9:1.

Seems on some things these highly experience builders/tuners agree, on other things, their experience and advice differ.

That being said, with future motors I will be sticking with 8.5 or lower, but with this motor, I am stuck with it, so I need to make what I have work.

Side note, will these help me hear detonation so I can tell if it is real or not? I have these at home.

https://www.amazon.com/Steelman-066...eywords=STEELMAN+06600+ChassisEAR+Stethoscope

 

[Kapok6]

What CR would you recommend for mild-medium hp e85 cars such as OPs? ( gets out pen)

FWIW my car hauled @$$ when my setup was as follows:

Ross 8.3:1
Eagle H Beams
Stock port head with Evo springs/retainers
One Legit HKS 272 and one Delta HKS 272 regrind (installed straight up with stock cam gears)
Evo III Intake manifold
turbo throttlebody

E85

30psi on my dsm76 HTA

Timing up in the mid teens at 8000-8500

Weighed 3395lbs with me in it. At 27psi I did 128mph, turned it up 2psi to 29psi, and clicked off a 130.75 and went home shaking with excitement. I beat the PISS out of this car doing 50 rolls in mexico every weekend for like a year and a half. As many races as I could find.

Eventually the car broke a wrist pin on CYL# 4. I like to think if I had HD pins in there, i'd still be out slaying blown V8's with that motor...

 

[bastarddsm]

I suspect those things will just give you a headache, and leave you $110 poorer. Maybe not though.

How much injector you got? Any chance you could juice it up with some E98 or Methanol to see if the knock goes away?

Further more, got any pictures of your head and pistons? Are the pistons down the hole, or at deck height? Flat tops or a dome? What's the head combustion chamber look like?

Lastly, buy some new plugs and get them gapped. Drive out to your spot, put a single fresh plug in it, make 2 pulls. Pull the plug out, and put a old one back in. bring it home and get a good high res in focus pic under good lighting. Post that and lets have a looksy.

 

[Kapok6]

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Injectors are 1550cc. 30-31psi has me at about 67-68% at 8750rpm

I'll try to do the pulls with a new plug this weekend. weather is garbage today but the rest of the weekend should be nice and I should be able to get some 2nd gear pulls in maybe tomorrow or sunday AM before traffic comes out.