need help tuning for smaller pulley

[cobracmdr]

Thanks for looking at this thread. So I followed Russ K's OL MAF tuning for my 01 GTP with just a k&N drop in. I tuned part throttle and WOT using my WB and it runs great and AFR errors are < 1 average all over. I had a little KR on the top end so I pulled a few degrees of timing out to squash it. This was last week.

Now I want to upgrade to a 3.4 pulley and some colder plugs and retune. I have my PE AFR commanded at 11.8 AFR right now...... So after I do the modes how should I retune? Should I lower my commanded AFR during PE to say 11.0 AFR, retune the maf, then up it back up to 11.8 ish to be safe and check for KR?

Some advice on how to safely do this would be appreciated!

Ken

[rnjmur]

Tune the MAF and make sure the AFR errors are still within check. You may want to check the commanded timing for the higher airloads as you may have to drop them down a bit. Normally just a pulley change shouldn't require too much retuning.

[murphinator]

what supporting mods do you have in place for a 3.4 pulley ?

headers ? plog/3" dp ? rockers? etc....

[cobracmdr]

what supporting mods do you have in place for a 3.4 pulley ?

headers ? plog/3" dp ? rockers? etc....

None of the above. Just want guide for how to adjust fueling. I'll put in some colder plugs, its a DD just looking ot make it a little more fun. I know those are complementary mods......if anything I'll do the DP.

Just curious how you guys tune these cars when you get more boost in the engine.... I think I have my answer, add some fuel and retune the maf, then lean out commanded back to 11.8. Then tune kr.

Just seeing what peoples tuning methods are, thats it.

[Perforator]

Just seeing what peoples tuning methods are, thats it.

Get a wideband, tune your MAF table to match your command AFR, then either adjust fueling or timing till your knock free.

[oakleafresin]

You can run a 3.4 on a stock car but it's going to require so much timing retard and extra fuel that you will be slower than you were when you started.

If it were me just starting out again, I would buy a wideband and wring out as much as you can from the stock pulley. You could run 13s on the stock pulley on a well tuned car.

Once you tune the MAF you don't really ever have to touch it again. At that point you add fuel using the PE tables.

[cobracmdr]

You can run a 3.4 on a stock car but it's going to require so much timing retard and extra fuel that you will be slower than you were when you started.

If it were me just starting out again, I would buy a wideband and wring out as much as you can from the stock pulley. You could run 13s on the stock pulley on a well tuned car.

Once you tune the MAF you don't really ever have to touch it again. At that point you add fuel using the PE tables.

Already have wide band, already tuned the car..... Just want a little quicker.. so maybe a 3.5 pulley then?

Ken

[murphinator]

. You could run 13s on the stock pulley on a well tuned car.

13's stock pulley:
http://www.youtube.com/watch?v=ZIRr8AbkNDg

there are many factors that affect what size pulley really makes sense with your combo

having a tuner and a wideband is great , if you havent bought ay pulley yet do yourself the biggest favor and buy a modular system so you can change sizes in a couple minutes because what pulley your combo can tolerate can change with weather ,altitude , available octane , and many other factors.

if you are in denver you may be fine running a 3.4 pulley with stock manifolds and a u bend still in place - in my experience at sea level with a plog /ported rear , 3" downpipe ,3" catback , a103's, drilled 180 stat ,etc... the only way I can run a 3.4 pulley is on 100+ octane fuel so at the track the 3.4 goes on that car while on the street depending on time of year and if I have my 3" catback on which is loud or my stock exhaust you may find a 3.5 , 3.6 , and occasionally but not often a 3.8 pulley on the car

my headers ,rockers car will run fine with a 3.4 on premium fuel summer and 3.5 winter.

follow the advice in the posts above from some knowledgeable guys and when you get your afr's dialed in and can run 18* of timing in the .92 cylinder airmass column with no kr its time to drop pulley sizes if you cant maintain 15* or more timing in the .92 column with 0 kr in my opinion you need to go back up a size , at least thats how I do it and like afr's for non intercooled with no spray around 11.2 at wot

[cobracmdr]

good advice, I have a 180 stat and I was going to run colder plugs and such. Right now yeah I don't have 15* timing at high RPMS, I actually pulled a little timing to get rid of some KR but I'm running 11.8 AFR in PE.......So sounds like I need to get some colder plugs and advance the timing a touch and see what happens.

good points, very logical and makes sense. thanks for dusting off the cobwebs....

[oakleafresin]

Timing is more important than AFR to an extent. I would shoot for 18-20* of timing with no richer than 11.2-11.4:1 AFR. If that means running a bigger pulley, so be it.

You want the engine making as much power as possible so that it requires less boost. The faster you spin that M90, the more HP it steals from the engine.

[danthurs]

Keep in mind dropping .1 on a pulley might get you 10hp, but end up costing you 4 to 8 degrees of timing at 3 to 5 hp per degree. As stated, your better off with a larger pulley and more timing. To run a smaller pulley a lot of people say get headers. But that rarely does the trick. High ratio rockers, or better yet, a cam is what will really do it. Best option is ported heads. don't fall in to the smaller pulley junk.

[cobracmdr]

Thanks guys, my last supercharged car was a 04 cobra and they loved smaller pulleys even with stock exhaust..... so thats where my experience is from......

Obviously with a crossover pipe, u bend and all kinds of restriction you cant get the air out already so putting more in isn't going to be as benefical.

i'll give your advice a try, I took my wideband out but my car is tuned now so I'll adjust the AFR to richer in PE and add in some timing and see what I get for KR.

Ken