4AG'T'E Surging on the road and dyno - tune?

[shelldrake]

Sounds spark related to me. I would start at the trigger. I highly doubt vvt is the cause. (it does make a big difference to torque/power once sorted though.) I had 2jzgte injectors in mine ( I think they were 440cc?) and was making 230ish kw at 18psi on a similar setup. I also had a big f$ckoff plenum and 3" cooler piping... I ran the standard fpr on the standard rail. If you think it's fuel pressure, just put an in line pressure gauge on the rail temporarily.

[Cuzzo]

Agreed its worth putting a fuel pressure gauge off the malpassi. I have found the malpassi's to be pos. Even try the stock fpr? Or better yet a sard one.

[fixeruperer]

its on a dyno ? if anything is wrong, you will see on the dyno..

[mattysshop]

Malpassi has a gauge on it permanantly... i don't have dyno sheets yet, BUT i do have tune files for it, pulled from the adaptronic.. if anyone wants to have a look at it, PM me an email address and i'll send it over... might help you guys see if there has been a silly mistake made etc..

also something which i thought was odd... the external gate (new version of the Tial 38mm one pictured) and even with the original tial gate was plumbed in using the side port ONLY... not the top port... i've always used the top port.. i read through that recent thread about 2 port external gates, just not sure how this would affect it, as i wouldn't think that the gate would actually function on anything but spring pressure with this port only being used.. has an 8psi spring in it..

[Duk]

Malpassi has a gauge on it permanantly... i don't have dyno sheets yet, BUT i do have tune files for it, pulled from the adaptronic.. if anyone wants to have a look at it, PM me an email address and i'll send it over... might help you guys see if there has been a silly mistake made etc..

Giz a look.

also something which i thought was odd... the external gate (new version of the Tial 38mm one pictured) and even with the original tial gate was plumbed in using the side port ONLY... not the top port... i've always used the top port.. i read through that recent thread about 2 port external gates, just not sure how this would affect it, as i wouldn't think that the gate would actually function on anything but spring pressure with this port only being used.. has an 8psi spring in it..

I only use the bottom port on my Ebay special external gate and it does a great job of holding waste gate spring pressure of 7 psi, but I'm not using any form of boost controller though.

[mattysshop]

Thread Dig -

my mate has got some results... well kind of... the turbo 'numbers' didn't match up when pulled apart and taken to MTQ turbo systems etc... while it was all apart he put a .86 rear on it, as the surging was 100% from the small .63 rear housing (according to the tuner, and a few other people)... so on it went...

17psi full boost, makes a massive 205fwhp........................................... .

apparantly it still does a little surging top end above 7000rpm.. so they just set the limiter a little bit lower..

car still has not visited any other tuners, my mate has sent the tune files to Andy from Adaptronic, the current tune and doesn't beleive there is anything wrong with it..

is it just me, or does that power figure seem awfully low for a fully built 4ag 20v head, all the custom fab work, and 17psi of boost... not that power output is what his ultimate goal is... i just thought that people could get this sorta power out of a stock NA engine with a bit of boost in there.. plenty of dyno charts of GZE turned turbo with stock ecu etc on lower boost, making more power, with no problems... and some of those home job turbo setups are pretty rough!

[trdee]

I made 180rwkw on a stock, original big port gze on 17psi so yeah that is quite low. Something isn't right..... Also my kkr430 has like a 0.58 rear housing and I have zero surge issues

[Encyclopedia Ronnie]

.64 housing being to small is crap if anything id say the gate response is out dumps to much gas to quick cant make it back up, the larger housing leaves more gas in the manifold and turbo housing so the gates afects seem less, if hes using an eboost the have a way of being plumbed for dual port wastegates so id say somethings a miss there if hes onli hooked to 1 tho tial do say that the top is a vent line .

fuel pump does seem really small to me i would think at least a 255 or similar, the other thing is how the regs set if they brought the preasure down a touch so they could get an idle with the 1000cc injectors they may not have enough presure in them up top to dump larger amounts.

the power output does seem quite low 205hp be somewhere near 170kw ish id say which is plenty but nothing massive,

[JP]

What sort of dyno's it being tuned on Matt? where were the vac lines being run from in the plenum? Any electrical noise present in the loom? Should be able to see it from fluctuating figures in the adaptronic runtime menu.

[Cuzzo]

I ran a 64 housing. No surge. Only wheels spin

[Ken_T]

Check cam timing. Motor not being able to take in air (surge) would suggest restriction in the inlet tract. I don't believe the move to 0.86 is the solution, just masking the problem.

Ronnie, 205hp is ~152kw.

[trdee]

which is craptacular for an engine setup like that..