LS/VTEC Turbo @ 13PSI

[Bugermass]

Setup: LS/VTEC Turbo @ 13PSI T3/T4 .70 Trim Master Power Turbo 550CC RC Injectors Stock Bottom LS with GSR Head Stock GSR Cams GM 2BAR Map Sensor We left the timming conservative (hense the wavey curve) cause the motors a bit tired and its gonna be on pump gas and been gettin alot hotter here lately. I was still working on smoothing out the fuel when it started raining and the dyno rollers were getting wet, so we stopped at 13PSI with a not so perfect A/F , but it runs good enough to have some fun until they can get back on the dyno. oh and bring me a 3bar map ; ) ..

[MADMAX]

Crank up the advance and turn down the boost. That way you get a nice even burn and smooth torque production, while retaining the same power. There will be less stress on the exhaust valves and turbine wheel to boot.

[Bugermass]

yeah we're gonna finnish when its not raining.. I'm gonna add some more timming once I get the fuel sorted out..

[Boosted K20]

how did u the owner have the dump tube routed? looks like that car could use a bit of timing. i hope ur wideband a/f was not reading in the 12's :1 a/f in the top end. lol,is that an outdoor dyno. haha oh,lower vtec. looks like it might run better at 5K!

[MADMAX]

how did u the owner have the dump tube routed? looks like that car could use a bit of timing. i hope ur wideband a/f was not reading in the 12's :1 a/f in the top end. lol,is that an outdoor dyno. haha oh,lower vtec. looks like it might run better at 5K!

A bit of timing. That thing needs a grip!

[hackish]

Crank up the advance and turn down the boost. That way you get a nice even burn and smooth torque production, while retaining the same power. There will be less stress on the exhaust valves and turbine wheel to boot.

This is not a good idea. More timing puts exponentially more stress on the bearings and rods as they have to deal with compressing a burning mixture as it approaches and passes TDC. The closer to MBT you run the engine the shorter it will live. This is why many people, myself included find MBT and then back off a number of degrees. More boost results in a mixture that burns faster so with less timing this is a far better way to achieve peak cylinder pressure at the proper point on the down-stroke. Nice numbers bugermass. Somewhere near 320whp on a mustang dyno is where I usually run out of fuel on 550RC injectors. What were you seeing for duty cycle at the top of your map? Obviously it's running way lean up there... -Michael

[blundar]

Honestly, I think you're all right and wrong, to some degree. Hackish is 100% right about motor lifespan running closer to MBT, making power with boost being safer, etc. Everyone else is right about the graph being choppy. 9 / 10 choppy graphs mean MISFIRES. You might not be blowing out spark totally, but it's enough to cause the chop. I4 motors will ALWAYS have a lot more chop than say a V6 or a V8 due to the inherently unbalanced design. My V8 buddy always freaks out when he mistakes my 400+whp I4 graphs for V8 graphs because of the choppiness. In any case, the reason why adding advance to a motor that is misfiring works to smooth out the graph is that cylinder pressure increases as you approach TDC. Firing the spark closer to TDC (more retarded) requires a lot more spark energy! Before I added timing, I'd gap the plugs tighter. Misfires can really fuck shit up if they're bad enough. If you aren't blowing the spark out completely, exhaust other avenues before just throwing advance at it.

[Bugermass]

Yea I know VTEC is low, I was tunning the high maps and didn't finnish cause the dyno got wet so I left everything as is cause it was mostely tuned at those settings.. So yesterday I bumped the timing up quite a bit, raised VTEC to 5000, the spark was blowing out bad even at .020 gap. .. Reading the plugs vs what my A/F meter was saying led me to figure out that my sensor was not working right.. Used a new sensor and was seeing 9.5 - 10.9 a/f so I fixed the fuel.. And yea the dyno a/f meter is always showing leaner cause its to close to the end of the pipe so I just rely on my meter in the car. Needless to say we picked up a huge amount of power from advance and leaning out the A/F to a reasonable amount.. last night at the track we had some missfires on top end, but only in 3rd gear, didn't have the laptop hooked up so we'll have to fix it later this week.. The result as it was we were neck and neck last night with a K24 Turbo hatch that was on slicks, and we were on drag radials.. Also neck and neck with a GSXR1000, that was pretty cooll lol.. And with the 550s were seeing a max of 70% duty cycle. Once we go back to the dyno to figure out the missfire issues I'll post a new graph.. Also the turbochargers.com manual boost controller is a POS don't buy one.. half a turn is like 4-5 psi.. I think the sputters on the top of 3rd may have been boost cut, I had it set at 15 and (MOST OF THE TIME) it was boosting 13psi, it fluctuates alot.. If you see the car, its like kinda just thrown together and a complete mess, so to get this kinda power and have everythig hold together was a miracle.. Thanks for all the comments.

[MADMAX]

This is not a good idea. More timing puts exponentially more stress on the bearings and rods as they have to deal with compressing a burning mixture as it approaches and passes TDC. The closer to MBT you run the engine the shorter it will live. This is why many people, myself included find MBT and then back off a number of degrees. More boost results in a mixture that burns faster so with less timing this is a far better way to achieve peak cylinder pressure at the proper point on the down-stroke. -Michael[/quote] Here's the thing, if it's not misfire, then that motor is nowhere near MBT. Of course you don't ride the edge of MBT, always give some room for error and back it down a tad. I do the same thing. With timing there is no more or less blah blah blah. Timing is simply set where it should be. Running more boost and then backing off on the timing to result in the same power output is not putting any less stress on the motor, it's actually throwing a lot of heat into places that don't need it. If you happen to run into detonation first, well then you stop there and do not continue on to MBT. Ignition timing isn't difficult if you understand some simple concepts.

[Bugermass]

This is not a good idea. More timing puts exponentially more stress on the bearings and rods as they have to deal with compressing a burning mixture as it approaches and passes TDC. The closer to MBT you run the engine the shorter it will live. This is why many people, myself included find MBT and then back off a number of degrees. More boost results in a mixture that burns faster so with less timing this is a far better way to achieve peak cylinder pressure at the proper point on the down-stroke. -Michael

Here's the thing, if it's not misfire, then that motor is nowhere near MBT. Of course you don't ride the edge of MBT, always give some room for error and back it down a tad. I do the same thing. With timing there is no more or less blah blah blah. Timing is simply set where it should be. Running more boost and then backing off on the timing to result in the same power output is not putting any less stress on the motor, it's actually throwing a lot of heat into places that don't need it. If you happen to run into detonation first, well then you stop there and do not continue on to MBT. Ignition timing isn't difficult if you understand some simple concepts.

Thanks for the info, everything you just said I am aware of (been tunning a while ).. We ran the conservative timming at first cause its been really hot here lately and the motor is old so we wanted to try not to cook it right away.. BUT.. it was a little too conservative, and with too much fuel due to my WB sensor being dead. The turbo manifold was glowing BRIGHT after runs and it was miss firing too much even with the plug gaps at like .020.. So I added more timming until the missfires went away and the motor started smoothing out while constantly checking the heat on the plug.. ( this was a street tune before going to the track ) Got the timming (still conservative) but alot closer to where it should be ( took out 2 deg on #3 and 1deg on #4 to match the heat showing on the plugs).. Fixed the rediculous rich A/F (bad sensor) and yay! No more glowing manifold.. I think the 3rd gear missfire on the track last night was actually boost cut, I wasn't driving or logging so I'm not sure.. Anyways it picked up alot of power just from the fuel and timming changes. I'll post a graph when we go back to the dyno. (were gonna raise the boost ). its a throw together motor just to have fun, if it blows they have like 4 more in the shop so they wanna just see how much we can make on the stock motor and have some fun until it finally pops.. DAVE:: thanks for the info on the missfire thing, I knew that advancing the timming would usually clean that up, but I didn't know fundamentally why it miss fires with too much retard.. I was actually gonna msg you and ask if you knew the physics of why, but you posted before I got a chance so thanks for the info.. DAVE::

[blundar]

MADMAX: You're actually kind of wrong. Too rich AFR / too little timing puts too much heat in all the wrong places - you're totally right. However, by doing so the only MECHANICAL pieces that encounter additional stress are the exhaust valves, turbo manifold and turbo wheel. The bearings/crank/sleeves/etc. take a lot less of a beating at the expense of efficiency going out the window... Well out the exhaust port to be more precise. Chris: You probably still need to throw more advance at it, particularly if you have ign adjustments off.

[Bugermass]

yeah I'll know more when we get on the dyno again, we did the last changes on the street at the last minute before going to the track, I didn't wanna add anymore until I get back on the dyno. were running NGk 9s (all we had left besides 7s ) and the ground strap is already burning a bit past the curve, so any more advance I'll wait till we get back on the dyno. Thanks again for everyones info.

[MADMAX]

MADMAX: You're actually kind of wrong. Too rich AFR / too little timing puts too much heat in all the wrong places - you're totally right. However, by doing so the only MECHANICAL pieces that encounter additional stress are the exhaust valves, turbo manifold and turbo wheel. The bearings/crank/sleeves/etc. take a lot less of a beating at the expense of efficiency going out the window... Well out the exhaust port to be more precise.

I can see what you're getting at. So having the combustion event past peak efficency, but increase boost to make the same power is going to create less pressure on the bearings? I don't know the exact force difference when the crank is at an increase angle, but increased pressure, so maybe you are right, but I can't imagine the pressure on the bearings being that much less.

[Bugermass]

I did some serious rework on this guys setup. Fixed all the piping and vaccume lines and some wiring, then did a serious retune.. At the same boost level with no leaks and everything working properly I made a bit over 390 to the wheels just leaning it out a bit and adding more timming till the motor seemed most happy. I have to go back and reprint the Dyno, I'll post it as soon as I get it.. He called me friday night while I was here in LA for my show and he told me he ran 7.5 in the 1/8th mile with a 1.8 60ft ... I tune a bit leaner than most people, and it seems to net me really good power results and so far havn't busted any motors.. Just have to keep a really close eye on the plugs during and a bit after the tune, but so far the stock LS/VTEC has held all 390 on 13PSi with no issues.. YAY!! AND tonight they called me and said he beat 2 or 3 cars from Inline Racing (another popular tunner here ina town ) and a 400HP car from St00pidfast ( my other competition ) ... All with nice clean looking \"Powered by ->> eCtune\" stickers on both sides of the car : ) so hopefully its gonna blow up in houston.. YAY Late

[calvin]

Nice work chriss... Keep up the good work.. Keep it up!