Mod turns very bad

[m1key1111]

Originally Posted by jayno20

The lowest fuel psi I see is 56... I thought anything over 50 was ok?

If your fuel pressure is lower than your commanded then you have a fuel delivery issue whether or not its in the mid 50s compared to some cars I've seen (normally in the mid 40's a the top of their run).

I'm still leaning towards a fuel starvation volume problem (irregardless of the WB A/F) and the main reason behind it is both rear cylinders failed and in most boosted applications when this happens it's because of fuel starvation to the farthest cylinders on the fuel rails.

17 PSI + Constant fuel pressure dropping + Only two rear cylinders hurt + high RPM 6600+.

That's my best guess.

[FunkedOut]

that's true.
the bank AFR might have been fine even though one cylinder was lean.

[Fastone21]

Stock cam will go to 7000 on any LS motor. However, when you spend the motor faster the super charger makes more boost. 17 psi with stock injectors and no BAP and plugs not cold enough on pump gas is a bomb. At a minimum 2steps colder plugs, ID850 injectors and BAP to start with.

[trasherseb]

i had fic 1000 injector and colder plugs

[trasherseb]

it seems that this happened several time on the lsa but people don t speak about it .... i understand that ...not so proud to break an engine ....seems to be a hot point on the heads and or a problem with oem rings at this level of boost ....

[Brice]

Originally Posted by m1key1111

I spent an hour reviewing the tune and this is my short summary of what happened with the supporting data below.

First I think you were spinning the motor to high (RPM) however what caused it to fail (my personal belief) was the almost 10 PSI drop in fuel pressure coupled with 16-17 PSI of boost.

-------------------------------
Tune:

Rev limiter set to 6900 (don't know why it's being spun this high with stock cam)

Power Enrichment (commanded AF)

3500-5500RPM 1.345 PE Commanded = 10.92 A/F
5750 1.295 PE Commanded = 11.35 A/F
6000-6250 1.278 PE Commanded = 11.50
6500 1.295 PE Commanded = 11.35 A/F

Timing, standard table 20 degress at 4800, transition to 15 degrees 5600-8K rpm

PE/COT spark advance correction table set to add 4 degrees 4800 rpm and up

-------------------------------------------------
Scanner from dyno pull:

No KR, timing at WOT 20 @ 4800 down to 13 @ 6500

Boost 15PSI @ 5K RPM, 16PSI @6k RPM, 17 PSI @ 6400 RPM, 17.5 PSI @ 6600 RPM (220.5 kpa)

Fuel Pressure (During WOT dyno pull)

4500 RPM 65.3 .935MV (narrowband)
5000 RPM 64.8
5500 RPM 64.0 .899MV (narrowband)
5762 RPM 62.2
6000 RPM 60.5 .881MV (narrowband)
6257 RPM 59.6
6605 RPM 56.6 .856MV (narrowband)

6900 on stock spring is an engine killer ...
and useless with stock cam.
no wideband ?

next engine, have a call to Lsx Calibration, (http://www.lsxcalibration.com) french tuner company with a lot of experience on LSA engine.

[Brice]

Originally Posted by Fastone21

Stock cam will go to 7000 on any LS motor. However, when you spend the motor faster the super charger makes more boost. 17 psi with stock injectors and no BAP and plugs not cold enough on pump gas is a bomb. At a minimum 2steps colder plugs, ID850 injectors and BAP to start with.

LSA springs are the same as truck one....
LS3 and LS9 springs are different and stronger
Valve floating past 6500 rpm ...

[trasherseb]

Lsx calibration before to comment please read the post I have a wideband
Second : a lot of experience in LSA ? How many did You mod ? It is well known that France is full of ctsv And zl1 ....

[JusticePete]

Stating the obvious, #7 is the hottest hole in the motor and at 14 pounds I would prefer a built up fuel system over a BAP.

Does anyone have water temp, oil temp and AITs?

[Brice]

Originally Posted by trasherseb

Lsx calibration before to comment please read the post I have a wideband
Second : a lot of experience in LSA ? How many did You mod ? It is well known that France is full of ctsv And zl1 ....

5 LSA and about 10 ZR1 ... and over 600 other LS engine ... (supercharged, camed, strocker, swap, etc).
Our shop car has a LSA too for R&D. Winning first round of ESLA euopean championship last month (drag racing).

the boost is a restriction mesure ... 16-17 PSI is too much to be safe on a stock engine ... and high rpm is not a good idea with stock springs.
What is your wideband ? a budget AEM/PLX one ?

[KaBoom1701]

Interesting reading....

[trasherseb]

Mr Brice it is not the place to make your avertissement first
Second If You want we can speak about a gt 500 engine that exploded between your shop And the dyno ( You found this funny in the hp tuner forum !!!)or the Last LSA You prog And wich You needed to come back original because Of smoke And loss Of power ?
GM gives 6600 rpm max for LSA
6900 is only 300 more
And everybody know here that Numbers given by GM are underestimated too keep maximum security for garantee.
Keep your advices for You And quit my post make your advertisement elsewhere.
Thank You

[Brice]

Originally Posted by trasherseb

Mr Brice it is not the place to make your avertissement first
Second If You want we can speak about a gt 500 engine that exploded between your shop And the dyno ( You found this funny in the hp tuner forum !!!)or the Last LSA You prog And wich You needed to come back original because Of smoke And loss Of power ?
GM gives 6600 rpm max for LSA
6900 is only 300 more
And everybody know here that Numbers given by GM are underestimated too keep maximum security for garantee.
Keep your advices for You And quit my post make your advertisement elsewhere.
Thank You

Yep, 6 years ago, I've logged on the street a mustang customer with a mail order tune ... engine explosed on first acceleration ... nothing I could do then. surprise. shit happens ... on 700+ car tuned. (hopefully we haven't tuned it).
Just after I've tuned the new engine, and the GT500 is still running strong. I have tuned 2 cars this week for the mustang owner. loyal and happy customer (Frank). I will be happy to communicate his phone number if you want explanation from him.

Yep ... there was an LSA who had issue coming to the shop 6 month ago for a tune.
We haven't done the part install ... just warned the customer about it. (certainly broken spark plug or clogged cats) Here is the video:
... not tuning related. The tuner is not responsible when a car come in a unhealthy state.

You seems to be a negative guy, just look at the bright sight and 700+ successull projects and happy customers.

btw ... I've got a shop CTS-V with LSA ... running strong, winning competition ... a lot of R&D and experience on the shop lsa. (cams, pulleys, E85, headers, fuel pumps, methanol, HX, every parts was evaluated)
#1 and #3 cars on european ESLA 1/4 miles organisation last month. follow us and support this week end for the round #2!

Once again the stock springs are weaks (same of truck one), valve are heavier the ZR1 and LS3 ones) and you've got a broken engine.... do you believe it now ? For information the stock rev limiter is 6300 not 6600
Over 6500 rpm with stock spring, valve floating occurs and engine blow up ...
Believe me or not ... just stare to your engine. Are you happy with your 6900 rpm?
If you want advices and results just trust experimented tuners ... or do yourself your tooner with engine fireworks ...

We've just ordered a stock LSA for another project and big power on centrifugal supercharger.

Don't hesitate to call me if you want tips. It's not adverstising (on a US forum as my customers are based in France and Europa)... it's free and purposed with pleasure. That's the way we are sharing our passion (and hate engine destruction ... even ford ones)

[Brice]

Originally Posted by trasherseb

GM gives 6600 rpm max for LSA
6900 is only 300 more
And everybody know here that Numbers given by GM are underestimated too keep maximum security for garantee.
Keep your advices for You And quit my post make your advertisement elsewhere.
Thank You

Can you post some of your engine pix ?
(for everybody kwowledge sake)
Even with cam and upgraded valvetrain I don't spin my engine to 6900 rpm. (useless and risky btw)