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[TTC]

I'm having a discussion on an mr2 board about tuning and such. I wonder if there is much truth to a statement similar to this.

"I would be REALLY surprised to find out you could even get close to MBT on anything considered "pump gas". You are usually OK running as much timing as you can in the boosted areas of your map as long as you don't run into knock issues (assuming reasonable AFR). In fact, I would think that if trying to run "high" boost on pump gas you are usually more worried about high EGT from retarded timing that is necessary to run higher boost on pump."

I was stating how i wanted to view someone elses 300whp map to give me an idea of what kind of timing they got away with as a baseline for street tuning. My plan was to knock of a few degrees off there map and keep adding till the trap speeds stopped increasing. I assumed this was somewhere in and around MBT.

Anyway, turned into a bit of a flamewar lol.

[Joseph Davis]

Let me preface my statement concerning why MR2 people are stupid by stating I tuned the car that holds stock 3S-GTE head power record @ 416 whp.  There was more in the car but it the wastegate was a piece of shit.

Now, MR2 people are stupid because they believe everything they are told by 3-4 people who supposedly know everything MR2, and no one else in the world can fathom a piston going up and down because 3S are magically different.  Some of these 3-4 people believe 3S oil pumps don't go bad, among other horseshit, and they all love Nemesis which is a self-corrupting non error checking pile of interface fail whose designer claims the firmware can't get corrupted by simply tuning the box despite it happening to me twice (although they run top notch if you can get through a tune without bricking the unit).

Now.  Tom, if you have a question feel free to ask it or start a thread for debate, but leave MR2 never done it but I heard some guy who isn't known outside of the MR2 scene horseshit on the MR2 forums.

 

[TTC]

Whats funny, is I got my answer. JD, I might toss you an email later regarding the tuning of my car by myself and brett. I've compared my maps to many others whom are dyno tuned and shit. Now I know its apples and oranges comparing tunes on different cars n shit, but I have fucktons more advance in my timing map than these guys and now that im externally gated im worried it will pop. Before it wasn't an an issue since it wouldnt hold boost to redline, but now i do.  I wouldnt mind a critique on your part, but in the end we both need to split on dyno time for  day. I'm slowly learning this shit, its a bit of a learning curve.

20lbs 4ag will turn u out.

Ninjaedit:

Maybe you can enlighten me a bit on MBT:

From my readings I've understood that the MBT curve is basically a depiction of how there is a point in timing where if you keep adding you wont make power. At this point you lose the cooling effects of pump gas and are nearing the knock threshold.  Are there different MBTs for pump and race gas?  Or is it more the fact that racegas lets you travel past the MBT point without knocking, thus creating more power?

[Joseph Davis]

FYI, pump gas MBT is race gas MBT until you start running out of octane.  Some people are just dumb.

[TTC]

Ah, ok thx. Been a productive week. I thought there was more power to be had in AFR tuning, but apparantly its not as effective as I thought.

Second Question:

If you keep pumping the boost, and retarding timing up top how do you combat the increases in EGTs from retarding timing to add more boost.  MBT stays the same, but you run out of octane so you gotta retard correct?

[98vtec]

you can lower and raise EGT's as well by changing the fueling.  If you have to lower timing and the EGT's raise, add fuel to cool it off.  The trade off will be "less" power as well as less heat.

[Joseph Davis]

If you keep pumping the boost, and retarding timing up top how do you combat the increases in EGTs from retarding timing to add more boost.  MBT stays the same, but you run out of octane so you gotta retard correct?

No.

Dumb faggots on HT who want to make 500-550 whp on pump gas with the net result of a 9K long block that lasts one oil change will tell you that you gotta retard, but the simple truth of the matter is that when you run out of octane the only solution is adding more octane.   

[narfdanarf]

If you keep pumping the boost, and retarding timing up top how do you combat the increases in EGTs from retarding timing to add more boost.  MBT stays the same, but you run out of octane so you gotta retard correct?

No.

Dumb faggots on HT who want to make 500-550 whp on pump gas with the net result of a 9K long block that lasts one oil change will tell you that you gotta retard, but the simple truth of the matter is that when you run out of octane the only solution is adding more octane.   

Some cars will respond a lot different to fuel changes than others.  11.0 to 12.0 change in A/F was worth 75whp in my car ~ 8% increase in power.

Also I wholeheartedly agree on the 500 pump gas retarding timing thing.  Been there done that, realized how retarded I was and decided to just put the car on a 117 octane diet.

[Joseph Davis]

Sounds par for course, narfy.  Past 11.5:1 indicated AFR, assuming that value is repeatable and consistent between vehicles/widebands/bunch of other shit which it is not, you're smothering the burn.  At your power level the difference in fuel volume between 11.5:1 and 12:1, with an eye to the volume of your combustion chamber, is significant.  Also, if the engine isn't fully loaded your indicated AFR is going to be leaner than the actual masses of air and fuel entering the chamber each cycle.  Kinda hard to correctly load 700+ FWD whp across a tire interface, and it's not like most cars have the traction they should at that point on the track.

So yeah, lot of special case reasons why your car isn't going to act like a 200-350 whp one.  Don't you feel special??

[narfdanarf]

very

[TTC]

If you keep pumping the boost, and retarding timing up top how do you combat the increases in EGTs from retarding timing to add more boost.  MBT stays the same, but you run out of octane so you gotta retard correct?

No.

Dumb faggots on HT who want to make 500-550 whp on pump gas with the net result of a 9K long block that lasts one oil change will tell you that you gotta retard, but the simple truth of the matter is that when you run out of octane the only solution is adding more octane.   

So really, the limiting factor is mainly octaine. Regardless of rod  and piston type and all that horseshit. If you want big numbers, it wont happen safely or for long on pump. Good thing I only want 300.  I'm asssuming this isn't really an issue at such a low hp level.

[Joseph Davis]

Maybe yes, maybe no.  You have to look at what other people have done and apply common sense to that.  If other people haven't done basic experimentation to determine limits (often resulting in broken shit) then you'll have to do so.  After a couple times (tuner wise) you get pretty good at spotting some of those limits before they do any damage.

OK.  Most imports have carbon drop forged rods, pretty good shit.  When you exceed the power limit of a rod it will 90% likely S-bend.  You see this a lot in the Miata crowd at the 330-ish whp level after a short duration at that power.

Cast pistons aren't "particularly" weak if you can limit their temps.  Most imports come with a pretty decent piston, but they are efficiency AND emissions engines so they go together tight to limit blowby.  Proceed to make power and shit gets hot, expands more than the piston's *clearances* are designed for, and the piston starts to scrape against to bore as opposed to transferring heat to the bore like it should, and temps go up.  Hot aluminum is soft aluminum, shit breaks.  If p2w and ring gap are correct most OEM pistons can handle more power than Dcommon forum knowledge" says they can.  Look at Vitaras, those aren't even a well designed casting but STD size is loose in the bore and CR is way down so they run cooler, and they simply work.

My gut feeling is your (4A?) can do 300 just fine. If it's a 3S and hasn't cracked a crankshaft yet it can do more.

[PhilStubbs]

So, this would be off topic without that last post.

JD, what do you think the odds of a "quiet" 75.5mm vitara block holding up to 400whp are? I am wanting to build a street car that doesn't sound like a diesel and makes 400whp on 93 octane.

[TTC]

I'm certain the 4ag im using is fine. I can't remember what my p2w was  but i do recall it was on the looser side.  The pistons are "pft semiforged' which is toyota nonsese for a nice strong cast piston.  The rods are liek 2-3x the wide of a D series lol.  I'm sure it will be ok, even the headgasket is stout considering its not 100% MLS.

Whats strange is ive "heard" of people running unopened stock supercharged blocks at the 300 range, yet at times the "built" blocks always seem to explode lol.  I don't know if its builder issues or what, but they seem to like to pop at 300 and its often ringlands iirc.  From what I have read here, ringland damage is usually heat related or detonation no?

When your are talking heat, im assuming you mean egts more-so than lets say block heat. What can I do to limit these heat issues, from what i gathered adding more and more fuel stops working at 11.5ish give or take.  So, keep from retarding crazy amounts of timing to try to make more power than what my octane has to offer and dont be stupid about it. Or is it as simple as ensuring decent airflowin the bay, a good rad and a better Tstat. I know in the miata motors like ours the 4th cylinder tends to go first. I planned on doing that weird coolant reroute thing they do.


Sidenote: What is considered extremely retarded? My motor is quite similar to a miata so would 12deg be far to retarded?  Its more of a theory question, since there are often so many variables.

I need to get my hands on some meth.

[Joseph Davis]

When I talk heat, I mean power.  Power = heat. 

EGTs are a furthest extent tuning issue, and frankly if I'm not operating an engine at it's extremest limit (with regards to octane) I could really give a fuck less about EGTs.  For example, in the 1500+ whp domestics you see SBF a lot less than SBC, since the Chebby bits are 1/3rd cheaper to build they are built 10 times more often and therefore have ten times the R&D put into them.  This has resulted in Chebby power being very reliable in the hardcore motherfucker power level (check www.yellowbullet.com for RMHTers with six digit incomes) whereas the Fords are *very* particular about individual cylinder EGTs.  Honestly, if you don't tune SBF slightly rich the imbalance appears in the 600-700 range, just not as amplified.

Broken ring lands are either tune problems or clearance problems.  To a lesser extent they are shitty piston problems.  With 4A having paper headgaskets, if the ring land problems are greater than headgasket problems it's likely a shitty piston.

[TTC]

I'm going to go with tune/clearance. Toyota guys are scared to make loose motors from what I can tell and generally do it on the cheap which is fine, but they dont do it smart.

[HiProfile]

I've read many a internet forum, so I feel I am uniquely qualified to speak about tuning.


75mm Vitaras are loose as fuck, and relatively so for "built" Honda motors too. I've also seen people use the Nippon LS pistons at a very high power level, so I'd agree with JD's p2w statement. I also know that no coolant + idle + .0035" Wisecos = rubbing when it overheats, so I can't imagine how bad a fresh OEM-spec motor can get when making big power. We all know a properly tuned stock GSR can make a lot of power, so the worn motor p2w clearances & squirters are staving off the 2 main issues with cast pistons.

As far as octane...I think I was talking to JD or sewell about that recently. Imagine starting with a conservative tune, you make a flat 140tq from idle to redline with perfect gas and a perfect [small] motor. Add 2* (or percentage, relative to piston speed) and it jumps to 145tq. Add another 2* and it jumps to 146tq. Add another 5* and it jumps to 147tq. You're finding the MBT of that motor, so you back it off a bit. Whoever it was said pump gas generally doesn't have enough octane to get MBT on most higher-boost Hondas. Instead you tend to get knock, which people think is MBT, so they don't back off enough (if at all) and eventually their shit fails. I'd surmise that's whats going on with the 'built' motors that pop at 300hp. People think their shit doesn't stink and get too greedy with timing.

[Eville140]

If you are wanting some good 3s info start hitting the old toyota boards,  since the 3tc is starting to become harder to find quite a few are switching to the 3s.  And the ricans listen to nobody,  they crank the boost till it pops, rinse repeat till they have it down.   
If I ever get sick of the 3tc my starlet will be getting a 3s or 4g63 swap (probably 4g since it's much cheaper and easier to get though  ).

[TTC]

Whats strange is this older fellow from the deuce forum has been doing this turbo 4ag shit since like the 80s. I'm not sure how he does it, but hes runnign almost 30degrees timing at redline, whille anyone else isnt running anything close to that. So I want to knjow how the fuck is he keeping the motor from knocking.

[92CXyD]

Whats strange is this older fellow from the deuce forum has been doing this turbo 4ag shit since like the 80s. I'm not sure how he does it, but hes runnign almost 30degrees timing at redline, whille anyone else isnt running anything close to that. So I want to knjow how the fuck is he keeping the motor from knocking.

Who says he is keeping from knocking? Could be he fuckin' deaf.  ;D

[TTC]

I think hes put like 60 000kms on the motor at 300whp and that kind of timing

[Robb]

I think hes put like 60 000kms on the motor at 300whp and that kind of timing

If the block or head has been shaved he could be compensating for mechanical timing with ignition timing. True up the cams to the crank and id bet this small bore motor wouldn't want as much timing.

[crxvtec91]

I think hes put like 60 000kms on the motor at 300whp and that kind of timing

Free race gas

[Joseph Davis]

Whats strange is this older fellow from the deuce forum has been doing this turbo 4ag shit since like the 80s. I'm not sure how he does it, but hes runnign almost 30degrees timing at redline, whille anyone else isnt running anything close to that. So I want to knjow how the fuck is he keeping the motor from knocking.

Who says he is keeping from knocking? Could be he fuckin' deaf.  ;D

Who says he is running that sort of timing?  Could be another dude with a timing advance light and no clue of how to use one.

[TTC]

I have nothing to really go on except his word, he posted a few bins of his timing map.

19.7,24.6,25.0,26.0,24.6,25.3,26.4,26.4,26.7,27.1, 26.7,27.8,28.8,28.9,29.2,29,4,29.4

4800 to redline at 240kpa

This is what he says he runs, who knows if hes compensating for errors in the mounting of his ign wheels ect.

I plan on just waiting till I get to the dyno and see how it goes.

[kgx]

I'm having a discussion on an mr2 board about tuning and such. I wonder if there is much truth to a statement similar to this.

which MR2 board?

edit. nevermind, i found it. that squelch guy is a real ray of fucking sunshine.

[TTC]

Yeah, so you have read the thread. See how im confused, I duno how hes running so much timing. All he gives are mixed elusive answers, hes more cryptic than JD.

[kgx]

dunno for sure. that's about 10deg up on what i'm running at that MAP as well. probably has the static CR of the motor significantly lower than stock, which would want... er.. be more tolerant of more timing.

i do find it odd that he's only making 307whp at 20psi of boost though. must be a pretty small turbine..

[patsmx5]

Yeah, so you have read the thread. See how im confused, I duno how hes running so much timing. All he gives are mixed elusive answers, hes more cryptic than JD.

Long time ago I put a trigger wheel on my car which makes the timing more consistant, and I noticed I could all-of-a-sudden run more timing everywhere. I knew it was the more accurate wheel. I ran more timing than most, and never had knock. Two years later when I redid my trigger wheel I discovered it was retarded about 8*. So I wasn't really running as much advance as i thought.

[Joseph Davis]

There's an RB20 swapped '71 240Z wiring disaster at the shop that has a fresh engine, but has never run on it.  Apparently the old motor died because the trigger wheel pickup was shaking all over the place.  Open the tune for it and all the timing figures are 35-42 degrees.  From -10 in/Hg to 30 psi, 35 degrees.  Apparently it ran wellish before the old engine came apart. Only way that shit went down was if the trigger was never properly synced and was effectively retarded.