Seriously ? You must have a vastly different pulley ratio to other Pettit guys .
Would like to see what your dyno looks like .... Might challenge the turbos for low down torque .....

 

would depend on the specific application i think. everyone is aware what happens when the turbo gets bigger. think about smaller though... ive rode/driven 8s that made 10-12psi by 2500rpm. that would mean the SC has a pressure advantage for a fraction of a second.

but that means nothing unless your only talking and comparing identical systems/motors.

I would ask this: OD- is your MAF scaled properly(none of this DIY nonsense we've seen pass as tuning here, but properly scaled/tuned)? if so then, the air mass would be much more important to compare

 

what turbo does that ?

 

low/manifold mount. one of them i never found out what he was hiding, but it wasnt the crappy greddy snail and this was before the current "options" for upgrading. the other was a 3071(at least i/we think thats what it is, lol) the Garrett might have been 2-300rpm higher to make 10psi, but it was certainly sub-3000rpm, which still means a fraction of a second of advantage if you care about pressure over flow, and of course start from a dig..

 

this isnt new though... this has been put out here before and iirc it was a thread/post from mysql that spurred this previously. iirc he showed logs or vid or something with his setup making either 9 or 11psi(dont recall) at like 2600-2700rpm. that was based on a 3071orsomethingsimilarbutnotthesamesuperdoublesecr etprobationturbo

 

ya i just IM'd him, said he was making 12psi by 3,000rpms

but this doesnt matter really... 12psi means nothing when comparing different compressors.

 

^ what did it drop down to by redline? If it even did

 

thats a tough one, this was a couple years back. the 3071 i think will hold 10 pounds or so all the way, if setup properly. the smaller turbo had similar characteristics to the greddy snail, kinda peaky/jumpy boost modulation, dropping to 7-8psi maybe at redline

 

certainly did not show in his dyno .....

 

aw brettus your STILL stuck on that stuff?

over the last 3 yrs or so we've seen dozens and more FI dyno's posted up here. disregarding manufacturer/retailer dyno's(for obvious reasons) how many good dyno's have we even seen? i can count on my 1 or 2 hands how many dyno's I've seen here that were complete, with no hiccups or issues, or tuning failures, etc

fwiw it might have been something he posted in logs or likely video knowing J, i dunno. dont care really anymore. i watched(maybe even took part) the discussion this leads to when it came up before once.

 

Does Jeff play with APV timing when he does his tunes via AccessPort or does he tune around the lean spot at 6000rpm? Because from what I'm reading it sounds like tuning around it might be the best all around general option... you get the low down flow velocity you need while keeping flow up with the opening of the APV higher up. I wasn't planning on installing my blocking plate with the GReddy turbo but this thread has got me thinking.... which could be dangerous haha

 

Not stuck on anything - just making an observation. If you have the relevant info , I would like to see it .


All 4 FI dynos i've done were without issue so that's one hand almost taken up LOL . But yeah - good point .



then why post ?

 

hehehe

i dont have anything, i just read what i see on the interwebs
you've done 4 now w/o issue whatever your trick, share it with all the ppl who have made multiple attempts and still dont have a complete dyno...

hmm well... my interest in the car at this point is only theoretical. and even that is pushing it lately. i suppose really its out of sheer f-ing boredom lol. i've cranked down all my hobbies in my life in prep for selling the car to buy a bike and, i dunno whatever. oh and there was that thing i told you about before.. but im too lazy, didnt keep up with the forum when BSE was at the house, so im not gonna bother - sorry for being a bitch for no reason then lol

 

no trick -I just make sure the car is performing properly BEFORE I go to the dyno . So when I put it on it's just strap her down and lets see what she makes - no dicking around trying to fix stuff.
That and I don't have to rely on anyone else to do my tuning

 

yep--i do have that boost at that rpm.
I dont think the scale of the maf was changed from oem. I run the pettit tune.
Brettus what did you lock the apv gear down with? Just reinstall the apv motor after cranking the apvs open and not hook it up?
OD

 

To deactivate just pull the plug . To hold open pull the plug when you hear them open after shutting off the ignition - but get your timing right

 

Lol --much easier than my way!

WHich position is open? With the magnet on the gear at the one oclock position?
OD

 

open is in the middle of the open close noise you have about 0.5secs to pull the plug in the middle of the sequence so you need the plug partially off to get it off in time before they start closing again .

 

its hard to hear in my car --the ssv makes a lot of noise at the same time. So I am going my gear position.
Anyone know--i used to but i have forgotten.
OD

 

lol ya i know, but the vast majority of folks dont fall into that category :-P

 

Which came first; the excuses or the fail?

 

had something funny to happen.
I made a slow test run with the apvs's locked open (i think). It felt promising. I only wound it up with 50% throttle and only to 6.5 K.
a/f's looked good, boost held steady, charge temps looked good. --OK
So i let off the throttle and shifted to a higher gear and was going to cruise ( iwas on an interstate entrace ramp).
I glanced at my charge temp gauge (temperure of the air post blower that is almost at the uim/lim junction) and dman!!!! It had jumped 150F to 250F!!!! My boost vacuum gauge was pegged at 30 of vacuum!
WTH!
I quickly switched my water meth back on and temps came right down, vacuum became normal in 5-10 seconds. Engine was fine---but WTH happened?
After scatching my head and not being able to find anything, I tried again at a much less load and the temps shot up AGAIN! But Only to 200F this time- it gained approx 100F degress in 2 seconds after I let off the gas. No Vacuum problems this time.
Something is going on. I had my w/m spraying during these runs. The spray was not on full since it is maf driven and I wasnt at full throttle.
No hiccups, no stumbles, felt good UNTIL i let up off the gas??
I am not doing this again until I find out WTH happened and know a cure.
I hooked my APV back up and this behavior went away.
I believe I am getting blowback some kinda bad?
ANYONE??
OD

 

I think you just answered your own question .
Leaving the APVs open at low rpm is a bad idea for low down torque and it seems you just discovered another good reason not to do it .

 

Seems like leaving APV alone is your best bet... as long as you can tune around it, best of both worlds, low down velocity and high rpm flow

 

I think you are right.
At 1st i thought --ok the blow by valve is messing up--althought it never has before.
I checked it and nope--it was fine.
Guess the port timing is such that this is not to be done --with my tune.
OD