Pumpgas Tuning: 1g head vs 2g head

[Black95TSIawd]

The harder I search around, the more confused I get, but I'm starting to wonder if a discussion like this has ever taken place. Please keep in mind that all my questions and statements are in regards to tuning on 91-93 octane pumpgas. NOT e85 and no type of injection. (water/meth/etc.)

I got back into messing with my DSM this past year and one thing that was important to me was making sure that I crossed my t's and dotted my i's. I have not hacked anything at this point with my setup and made sure everything was done right and with quality parts.
Prior to my rebuild, I was plagued with what I thought was a horrible phantom knock issue. My car hated timing. Even after a little mix of racegas, I could never get my max timing numbers to mimic any of the information on tuning I have read or was told. Every log, every pull, I was stuck in the low low teens for timing advance. However, every search and every log I've been able to pull up show's that people can get away with what looks like very high teens of timing advance. The norm on this board seems to be 19 to 22 degrees of advance. That is at least what everyone seems to be telling everyone to shoot for. One thing I recently noticed, every log I was able to find, or a particular discussion, or even the people giving advice had or was tuning a car that had full 6bolt longblock.

Now, one thing I never seem to see anyone discussing was the difference of tuning a motor with a 2g head or a 1g head. Its common knowledge that the stock 1g timing curve lands you somewhere in the low 20's by redline. The stock 2g curve maxes out at 16 degrees by redline. And to bring up the EVO 8 or 9 head, their stock max timing is set to 14 degrees by redline. So, it seems that the engineers at mitsu have adjusted the tunes on the vehicles to reflect the efficiency of the motor.(or something to that nature) My question is, do tunes on 2g heads require less timing than 1g heads? In my personal experience even now with a FRESH engine, enough fuel, and good supporting mods, I was able to squeeze out 17 degrees of timing at redline with 15psi of boost. At 19psi, around 14 degrees of max timing, and once I set the boost higher than 19, my timing dropped to near single digit levels. (I have a TD06 20g for reference)

What I would like to discuss are your pumpgas tuning techniques. But, I would like you to provide a little more detail and describe what motor(displacement) and more specifically what head is on your motor(1g or 2g). I’m sure there are some of us out there that have tuned multiple cars and maybe have noticed a trend. OR, I could be just talking out of my ass right now and need to be pointed in the right direction. Either way, this can probably turn into a good discussion. And please, only post about YOUR own experiences. Don’t post about what you read one time or what you heard from John Smith. Only post about what you’ve done yourself.

 

[ramsack]

It's not only the head, but the compression ratio. A 1g is 7.8:1 with a 47cc head, a 2g is 8.5:1 with a 43cc head, and the Evo is 8.8:1 with a 43cc head. People putting 2g pistons in a 6-bolt and using a 1g head aren't going to be 8.5:1 anymore either. You basically need to KNOW what your compression ratio is before making assumptions that your timing is too retarded. You have a 6-bolt build, and I'd assume that is what the pistons were ordered for which Arias would calculate their compression ratio with a 47cc head, but you have a 2g head (43cc), so your compression ratio is probably more than 9:1. Also consider if the head needed resurfaced and if the head gasket is thinner than stock.

 

[Black95TSIawd]

My piston's are also 9:1 for a 6bolt and my head was cut twice before. My headgasket is .051 thick and i'm not too sure what the stock thickness is. I did not think of the combustion chamber size differences, thanks for the heads up. Maybe my car will be happy with low timing advance.

 

[Gstclipse69]

On my current setup now, before I abandon pump gas for e-85, I have a stock 6 bolt, short block and head. Stock headgasket but the head has had .004 taken off of it. I run 21-22 psi on 93 octane with 12 degrees of timing.

 

[JEFFREYCASTGSX]

Your car is boosted, and it does not like timing, depending on boost level if you cant get above 15 degrees then dont be surprised. Most stock timing maps for 4g63's peak at low numbers, like 14-20, 1g's were tuned a little bit more aggresively than 2g's or evos and it really has little to do with head design so yeah you might be looking in the wrong place. Its really as you go up in boost/airflow you naturally can not run as much timing. Its much harder to hit the MBT with forced induction as the increased pressures and heat cause more knock/detonation.

Just keep in mind that you'll make more power with timing than with tuning AFR, BUT you'll make more power with more boost than with timing or AFR. Might want to do a lil search on phantom knock as some of these older cars can easily exhibit it.

 

[ramsack]

If I can run stock 1g timing on 9:1 NA pistons then there shouldn't be a problem for anyone in this thread running more timing. That's on 93 octane. I do have knock but it's 100% phatom due to motor mounts and a cut off downpipe. When I first got it running and it had an exhaust and better mounts it hauled ass like a 3000gt.

 

[williillii]

it hauled ass like a 3000gt.

Sorry to interject. But since when does a 3000gt haul ass??

 

[whe3ls]

It's not only the head, but the compression ratio. A 1g is 7.8:1 with a 47cc head, a 2g is 8.5:1 with a 43cc head, and the Evo is 8.8:1 with a 43cc head. People putting 2g pistons in a 6-bolt and using a 1g head aren't going to be 8.5:1 anymore either. You basically need to KNOW what your compression ratio is before making assumptions that your timing is too retarded. You have a 6-bolt build, and I'd assume that is what the pistons were ordered for which Arias would calculate their compression ratio with a 47cc head, but you have a 2g head (43cc), so your compression ratio is probably more than 9:1. Also consider if the head needed resurfaced and if the head gasket is thinner than stock.

both heads are 47cc/48cc the 4g61 and 4g67 and 43cc/42cc

 

[ramsack]

Sorry to interject. But since when does a 3000gt haul ass??

It's called instant torque from displacement and tiny turbos. Something a 7.8:1 will never have.

both heads are 47cc/48cc the 4g61 and 4g67 and 43cc/42cc

I'd like to hear more chime in on this. Reputations of information are wary. We need an engine builder like BogusSVO chime in. Every 0.007 is 1cc off the volume of the combustion chamber, though.

 

[whe3ls]

will if you look at 1g and 2g pistons the dish is smaller.

1g/2g head bottom vs 4g61/4g67 top (not 100% sure but you can see that one is smaller)

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[Black95TSIawd]

If I can run stock 1g timing on 9:1 NA pistons then there shouldn't be a problem for anyone in this thread running more timing. That's on 93 octane. I do have knock but it's 100% phatom due to motor mounts and a cut off downpipe. When I first got it running and it had an exhaust and better mounts it hauled ass like a 3000gt.

On what Turbo and i'm going to assume you have a 1g head?

 

[whe3ls]

if you have a 2g you most likely have a 2g head, unless it has a 6 bolt. easy way to tell if you have a 2g head is that two exhaust studs are bigger than the rest. 1g heads the exhaust studs are all the same size. there are alot of differences between a 2g 1g and evo's that will effect there tune.

 

[gixrman]

ramsack has it correct when stating that compression is a major factor in knock and timing. Its all around combustion chamber HEAT. If you run low compression and high boost or high compression low boost either one will require different timing maps. Even cranking up the boost which pushes more heat in. There are alot of things that can effect your motors sensitivity to knock such as incorrect spark plugs, oil in the compustion chamber, carbon build up, shitty gas, incorrect heat exchanger or over worked one, etc.

Your boost setting isn't that high for a 20g (thats assuming your running an aftermarket IC) i ran my old 16g to 20-25 which is out of the compressor effency range which i had to comp. with water injection to get my timming to come back up. Of coarse my motor isn't stock either with evo8 pistons and FP1,2 cams. So I don't know if that is giving me a 8:8:1 or lower or higher based on the 2g head cc compared to the evo, but I had to compensate for it.

I guess what i'm saying is there are alot of factors that affect how a motor runs and you have to look outside the box when tunning. The minute you start taking things off and changing things to how a motor performs it changes alot of other things like timing. For some reason these 4g63 motors all run differently, you could take all of your components and slap them on another one and it will more than likely run completely different.

 

[brian9397gsx]

Im interested in this cause currently im debating on running my 1g head intake combo or my 2g head with rvr intake hogged out to accept 1g throttle body.

 

[donniekak]

if you have a 2g you most likely have a 2g head, unless it has a 6 bolt. easy way to tell if you have a 2g head is that two exhaust studs are bigger than the rest. 1g heads the exhaust studs are all the same size. there are alot of differences between a 2g 1g and evo's that will effect there tune.

The 1g 7-bolt heads have the larger end studs also. Along with the large 1g ports. The way to look for a 2g head is the 4th mounting location for the water housing.

 

[Black95TSIawd]

My mods are in my profile, but for reference: 6bolt with 9:1 comp, 2g head, S2 cams, venom SMIM. I built my motor with hopes of trying to flow as much air as possible with the best efficiency. I was hoping that I could get a decent tune on her(decent to me at one point was running a lot of boost with a lot of timing) But, what i'm gathering at this point that low timing doesn't necessarily mean low horsepower.

if you have a 2g you most likely have a 2g head, unless it has a 6 bolt. easy way to tell if you have a 2g head is that two exhaust studs are bigger than the rest. 1g heads the exhaust studs are all the same size. there are alot of differences between a 2g 1g and evo's that will effect there tune.

Read my profile dude, I have a 6bolt and kept my 2g head.


Please stick to the topic at hand guys. I don't want this thread to clutter up.

 

[SBR Joe]

I dont necessarily think the timing maps were different because of the heads....maybe more so because of the compression differences and just the way they decided to set them up.

I switched from a 1g head to a 2g head on my 14b record raper Laser, and the only difference i had to do with the tune was tweak it a bit down low because i picked up a substantial amount of torque from the 2g head over the 1g. Just had to pull a degree or two of timing out where peak torque came in, but that was about the extent of it.

 

[Black95TSIawd]

I dont necessarily think the timing maps were different because of the heads....maybe more so because of the compression differences and just the way they decided to set them up.

I switched from a 1g head to a 2g head on my 14b record raper Laser, and the only difference i had to do with the tune was tweak it a bit down low because i picked up a substantial amount of torque from the 2g head over the 1g. Just had to pull a degree or two of timing out where peak torque came in, but that was about the extent of it.

That is a rather smallish turbo, BUT, this is at least some solid information.

Thanks, Joe.

 

[SBR Joe]

That is a rather smallish turbo, BUT, this is at least some solid information.

Thanks, Joe.

Haha youre not kidding, 11s isnt easy with it .

Next year when i get it lower in the 11 sec range, i have an HX40 to slap on to see whats up. But yeah, its solid info none the less for you.

 

[ramsack]

I'm on an Evo3 16g. Wastegate pressure. The larger turbo you get (or more efficient, rather) the cooler the intake charge will be at a set PSI. High compression engines favor larger turbos because they are about airflow and not cylinder pressures. People will always say that if you don't use a turbo to its maximum that it's just a waste. I don't hold that true for high compression builds.

 

[hediki12]

evo 8s run any were form 18-15* by red line 7.5k)and 9s run any were from 11-9 * @ red line(7.5k). i highly doubt on the non mivec 4g63s that it was the design of the cylinder head that made the most impact on what they(engineers) deem correct as proper timing.... you have to remeber 1gs ran a 14b, 2gs ran a t25, and evos 7-8 ran a 16g, and the 9s a even bigger 16g.(psi and cfm also played a roll) more efficient a motor is the less timing it will take. so having the evo and 1g having a bigger turbo played a higher roll in the timing curve . make your self a set of det can and make sure that its phantom knock people jump on that ship o 2 often.

off topic kinda: also i guess its a dsm link lingo when you ask for timing you guess refer to the redline timing . to the op i hope your using a progressive timing curve rather than a flat 10* or 12* or what ever # people throw up.

 

[gixrman]

On linksV3 you can load a EVO8 stock timing map, a slightly modded evo8 map, and a evo8 GSR thats even more aggresive. Oh the joys of DSMlink.

 

[Black95TSIawd]

more efficient a motor is the less timing it will take.

This is exactly the reason why I started this thread. It seems that bigger turbo plus more effecient motor = less timing during WOT.

off topic kinda: also i guess its a dsm link lingo when you ask for timing you guess refer to the redline timing . to the op i hope your using a progressive timing curve rather than a flat 10* or 12* or what ever # people throw up.

Its very progressive starting at 5 degrees during peak torque and advancing nicely to 12 by 8k rpm.

 

[njdaewoo]

I went out tonight and did some tuning? Guess what I found?..... FUEL!!! I had my fuel trim set to deliver 11.5 air to fuel ratio.. That had me with about 4 counts of knock in the 5k to 7k rpm range (In that range I was only at 7 degrees of timing so the computer would pull about 2-3 degrees and drop my total timimg to about 5). I enriched my injectors to deliver an air fuel ratio of 10.5 and the knock went down to .07 in the 5k to 6k rpm range and the upper rpm range (6k to 7k RPMs) dropped down to 2 counts of knock. Im going to drop my air fuel ratio to 10.0 and see if that gets rid of the knock completely. I sure hope so because then I can start bringing my timing back up to respectable levels (at least 13-18 degree range) Oh, right now I'm running about 23-24 lbs of boost and it takes me about 2.2 seconds to go from 70 to 90 in 3rd gear.... It was about 2.8 to 2.9 seconds before the Comp Cams change and adjustable cam gears! It seems like my car likes extra fuel...

 

[clockworktoy]

I've ran both 1g head and 2g heads on a stock 6 bolt bottom end with a 60trim turbo at around 23 psi on piss water california 91 octane. The biggest difference in my experience came from the added torque from the 2g head/manifold combo. I did have to bump down my timing in the midrange and spoolup to prevent knock (on the 2g head). IMO i wouldn't be obsessed with running X amount of timing, since all cars are a bit different (not to mention who knows what some set their base timing at) your experience might be different from others.