boosted k20

last night i was tuning one of my friends car on crome gold. his setup is a D16Z6 Vitara set up on an ebay 57trim turbo, log manifold, 880cc, 3 bar, tial waste gate, 255lph fuel pump, 2.5 to 3" open downpipe. previously we were running a Y8 head with a ZEX cam i believe on this same vitara block and it made 280whp with a leaking exhaust manifold and roughly 20+ psi (owner fixed the leak after the tune and the car did run 11.7 in the 1/4 mile w/o a retune) The head and cam got messed up so he threw on a stock head and cam on the vitara block. i was tuning this setup last night and at 10 psi the car was only making 185whp, which to me was pretty low. timing was bumped up to around 24-25* on 93 octane to get this HP. so we turned the boost up to 14 -15psi and the car was only making 225whp. i figure the stock cam was robbing the power but the car should still make more power at this boost. so i decide to turn the boost up all the way to see how much power will go up. boost was turned up to 28psi and the car only made an extra 4whp for a total of 229 whp. Timing was roughly 13* at this boost level on pump gas. i figured something was seriously wrong since hp didnt dramatically increase. we did a compression test and it showed 150psi across all cylinders. did a boost leake test with a smoke machine and no leaks were found except for a small one under the throttle body (a few cars i smoked test had a small leak at the same location, so i doubt thats the issue). Timing was set on the dizzy to 16* to match the ecu timing before tuning. we reset the timing belt too and the same thing, no power. before the tune, valve lash was set to .007 int and .009 exh.

Have you seen anything like this? i am stumped. i never seen this before. he did however send the turbo out to get rebuilt since the previous tune (ebay turbo). Turbo was very laggy as it wouldnt start spooling till 4500, full boost by 6000 rpms. i am leading towards a bad head (the head did come off a working motor as per my friend) or a bad turbo rebuild (but it did hit 28 psi... so i dunno)

Also another issue with the car is that it was extremely hard to start. a couple of times we had to roll the dyno drum and "kick start" it. Maybe leaky valves???

Any ideas? i will see if i can get a hold of the dyno graphs.

nce

I had the same problem ended up being a bad dizzy tried and checked everything car didnt break up or run bad just wouldnt make the power it should, tried a diff dist and voila still dont understand it

robfrmny21

150 psi? show it be that low?

do not tell me its cuz it has low compression pistons in it.
does is break up[ and all, smoke at all?

the difference between the two combustion chambers on the heads really different?
look at the lil things first.

is the t-belt dead on????????

boosted k20

-150psi is good for vitara pistons
-motor not smoking
-timing belt checked out and readjusted. no difference in power
-car revved out clean, no break up


im gonna see if a new dizzy will make a difference

nce

i bet thats what it is my ls did the same thing very slow building boost and quit making power on the same tune with nothing changed i thought i hurt the motor everything checked out ok just 10psi to 20+psi there was no power difference car had no breakup at all very strange first for me

BigMike0147

BUMP THIS FROM THE DEAD!!!

I think I'm having a similar issue, and I want to know if anyone else has seen the same. I'm only picking up about 30 whp with my LS (built bottom end/stock head) with a jump from 8psi to 16psi. To me that's just not right.

If NCE is still around I'd like to know his experiences with his LS, but I'm thinking he's not.

So if anyone else has ever had this boost/power ratio problem, please chime in and share your expriences. Thanks!

BigMike0147

Bump this up!

No one else have this issue before??

crvtectim

Can you give us some more info on your setup? Turbo? Intercooler?

BigMike0147

LS motor
Supertech 9.7:1 CR pistons
Eagle Rods
Catch Can Setup
STC GT3251b turbo (brand new)
ebay intercooler (good for about 350 hp)
Aeromotive 340 lph fuel pump
PTE 525cc injectors

I think that's most of everything that might be somewhat relative

rich7777

Hey Mike, have you got any graphs ? I.e. Boost vs afr & power..

Also has the correct amount of ignition timing been used ?

BigMike0147

I'll have to see if I can get into photobucket when home later. I think I have a graph on there. It might also be in the LS thread on here from my first run. My second run with new turbo, manifold, downpipe was almost identical, but at less timing as the tuner said he was picking up some knock.

So that tells me that the turbo is definitely more efficient to make the same amount of power (yet low) on the same amount of boost with less timing. I believe he said he had to pull out about 5*.

If you send me your email, I can send you my screenshots of the map (first one) and you can look over it. I'm also in the process of sourcing out an OBD2 dizzy and trying that also for the next run. I'll just use a conversion harness, but this will give me a good chance of having a "fresher" dizzy.

SPOOLINmatt

i had a turbonetics t70 once. it made 500 at 25 psi. I threw it in the dumpster.

BigMike0147

Yeah, I built the motor recently myself to specifications. Compression is 185 across cylinders.

The first time I went to get tuned, it wasn't detonating like it did this time evidently. And the tuner said the same thing that it will be one of the first things looked at and hook up the mic if need be this next time. It's tuned on Neptune, but the screen shots I have are in Microsoft Word so that they could be reviewed. I haven't saved the current tune yet, but I need to (to see all of the timing differences and whatnot). I will email you my first maps so that you can have a look.

nealnanoHX

MMMmm adding more boost and not making more power, Ebay intercooler. Sounds to me like you may have maxed out the intercooler. What are your air intake temps reading and how much boost are you running. It could be other things as well thought.

BigMike0147

IAT during pull is about 130F (stock sensor location). My tuner says that isn't bad.

Boost4Breakfast

cam timing would be my guess. Too much overlap and reversion. a lot of reversion will cause detonation and artificially higher boost readings

BigMike0147

That's interesting ^^^^

I've never thought of that. But mechanical cam timing should be correct since I had just adjusted valve lash before I went and got it all in spec (marks were lined up on gears too).

I appreciate the ideas though guys. Keep them coming please

Boost4Breakfast

in kinda new to hondas, but yer dual cam right? the ls-b18, not referring to a d-series?
edit: you said "gearS" so im assuming B. maybe your cam gears slipped on the cams themselves. you know that dowl in the cam is used simply to line the gear up and is not designed for any load. grab a set of adjsutable and set the intake @0 and advance the exhaust 2-4 degrees on the dyno and see what it produces

shanebadoo

I am also having a similar issue right now. didn't have it before, but I have it now. It's making me pull my hair out. I'm on 16 psi right now with a 6262 and making no power. Something is seriously wrong!

No leaks at all. plug gap at 26.
84 cp 9.7-1
89 stroke ge sleeved
6262 .82 @16 psi
skunk 2 tuner 1 cams @ 0 (ran them like this before and made crazy power with the 30 r)

right now in the process of swapping parts one by one to see if I can find the problem.

I have also realised when reading the datalogs, the boost is building really slowly, at WOT i'm only getting the 16 psi at 6900 rpm, how is your boost building bigmike?

Freshdot

this **** cray

BigMike0147

My boost builds well. I believe i'm at full boost before 3500-4000 rpm. I'll have to take another look to be exact (will on way home). I'm only on 8psi now, but 16 wouldn't take much longer. It sounds like you might have boost leak also since it's taking longer for your bigger displacement engine to spool the turbo (granted I don't know how big your turbo is in relation to mine, maybe Shodan could help with that).

Breakfast - Yeah, it's a dual cam engine (LS). I know this thread originated from a D-series, but "nce" referred to his LS motor in post #5, so that really raised my interest since it's the same motor and the only thread I could find about a similar issue. That being that power at 8 lbs of boost is reasonable (around 200whp), but when increasing boost by 8 more psi I only see around a 30whp gain.

And also, my cams are in the process of being made. I'll be building the head some with new cams before my next trip. This will be to also cancel this out as being a "limitation"

kyden

is your flex section in good shape? i've seen certain styles collapse.

BigMike0147

Flex section of the downpipe?? If so, that won't matter for power purposes because it is after the turbo, so it's just an exhaust leak. But none-the-less, mines in good shape

rich7777

Exhaust gas reversion slows down the burn rate of combustion. Intake reversion just lowers the VE of the engine. To much overlap on a boosted engine and you'll just blow fresh mixture out of the exhaust. All of these will actually lower the engines chance of detonating.

Edit: we both right, your case would be extreme and causes by excessive back pressure.

rich7777

I've got your email Mike, i just can't view it properly yet. I'll take a look when i'm at home on my laptop as i only have my phone for internet access at the moment. I don't think this problem has anything to do with the tune though. It seems to me that when your hitting a certain power level the engines just hitting a brick wall. We need to work out whats going on inside the engine why this is happening...

A few thoughts :

when this engine was assembled was there anything that could create a hot spot in any of the combustion chambers ?

was there anything that could of caused a restriction in the coolant gallerys ( either a blockage or a build up of lime scale that would of lowered the heat transfer rate) ?

Has the engines coolant system been bled properly ?

What power rating is your octane good for at your compression ratio ?