Steve@C56

Past engine was stock LS1, large cam kit (23x/24x, 63x/63x lift), A&A v3si kit, 3.4 pulley, ID1000, 255lph pump, Longtube, E85, 20/22° advance at wot, and done 7500rpm with 12afr, and never lack fuel since the ID1000
For the new engine, i add stroker, 11.x:1 pistons, 300cfm airflow head job, LS6 intake, from 3.4 to 3.125 pulley, from 7.5 stock to 8 OD damper
Result : BIG power/torque from idle to 5500, and run like a diesel from 5500 to 6000 (doesn't want to force engine to push over 6k)

Log at 6000rpm show 20° advance, 11.x afr

Can i lack fuel and having again good afr ?
Can my stock a&a dump valve should be full open at 5500 and cause that ?
(my last option is valve float, but cam/double spring/valve/pushrod/head is the same as before unless the airflow job...)

Any idea ?

a/c man

Could be belt slip.

blown81bu

Belt slip im sure when my 8 rib slips shuts down at 5900 rpm

Steve@C56

i had just think to belt slip juste after posting...

but if it's belt slip, i probably can go over 5500 when no charge (in neutral or low gear like 1st or second), no ?

(in fact, i havent test in neutral because i have tune a lunch control at 4400, but i can detune it)

Steve@C56

I read that when belt slipped, it left belt dust all over the brackets. mine are completly clean (but the new engine have just 5h/-100miles of running)

I take the car to do a 200/300 miles cruising right now, i will see... but cruising is cruising, no reason to go over 5500 with a torque monster at low rpm, i will see

Steve@C56

No belt dust on the brackets

so, going what route...

upgrade fuel system ???
upgrade dump valve (spring or size) ???
upgrade belt system ???

robert miller

I would look at valve springs. I am running 8 rib set up with flip drive zero belt slip..

5 Liter Eater

Sounds like valve float to me too. changine pulleys, adding cubes, opening up the heads. All adds airflow and boost.

Steve@C56

Wow, 2 votes for valve float

How can i confirm this ?

The only thing i change on the valve train is my lifter (from stock LS1 to new LS7), and i have read 2 cases of valve float :
- if spring are not for the cam spec
- if pushrod are not at good size
It would not be my case
(but i have not check the springs, no reason to have broken them, but **** append)

And, how can i fix it (it was custom kit with PAC double spring kit and cam with powerband to 6900rpm on 346 but i was using it to 7400 on drag strip)

a/c man

Belt slip my vote

Steve@C56

I know, you are my first anwerer

Can it be without belt dust ?
Can be as ... hard issue as i cant go over 6000 in 2th gear (realy curious in my mind because even in NA, my stroked cammed engine sould go +7000)

BUT, i forgotten to tell... I know the belt i use have not the perfect size, the only i have are too short... for break-in the engine, i have to pull the a&a automatic tensionner, and tighten the manual tensionner at max...
It was not the final mount, i have to order the good belt (not exist in a shop here in Europe), i was sure that i having not 100% power at wot/high rpm/4th or 5th power, but i'm upset to not be able to go over 5500/6000

5 Liter Eater

You didn't mention springs before, it seems less likely if the springs came along with the cam. But FI needs more spring pressure than NA. It would look like a big dip in the TQ and HP at ~5500. But there's no "test" other than to take one or more out and the seat pressure tested at installed height. You'd want to see in excess of 150#.

Steve@C56

Springs are PAC Racing 1200 series "severe duty dual valve springs", special spec for FI, included in the FI custom camsahaft complete kit
I think it was 1207
Here are the spec :

Part# ....................................... PAC-1207X
O.D. Outer (in) ......................... 1.304
I.D. Outer (in) .......................... 0.950
Damper ................................... No
I.D. .Inner (in) ......................... 0.680
Install Height (Valve Closed) (in). 155 @ 1.800
Open Load (Valve Open) (LB) ..... 436 @ 1.150
Spring Rate .............................. 433
Max Coil Bind (in) ..................... 1.000
MaxLift (in) .............................. 0.700

I havent the tool for mesure
I will ask if somebody have it in my area

inspector12

Valve train is my guess as well although I wouldn't be running that type of timing with the added CR as well although I'd guess that if you were having a real issue it would show knock etc... But still shouldn't stop it from pulling up top. And thats just my opinion so who cares, but checking spring pressure and the preload on the lifters as well as are you still using a 5/16's push rod? If so I'd be lookiing at something a little stronger like a 11/32 .120 wall if a 3/8's is out of the question. Just a few things to look at. If they just did work to the heads. You should be checking these things as well as push rod length because if they decked the heads and or the block it will change what you need. and if the ppl who ported the heads sunk the valve any it will change your installed heigth and the spring pressures etc... It all seems like small stuff, but some of the small things will come back to bite you in the *** lol! GL! Hope these things get you to looking at a few things and you find what your looking for. On my FI stuff I like to see 170-180 on the seat pressure for reference.

Steve@C56

Vote : Another for valvetrain

Timing : I use E85, and 20° / 15psi is not so high
=>http://brucerichards.com/e85.htm
6 psi / 35 degress total timing / 575rwhp
13 psi / 29° / 872rwhp
20 psi / 24° / 989rwhp
30 psi / 20° / 1066rwhp

CR : E85 is 105 octane, no risk with less than 12 CR
=>http://www.daytona-sensors.com/tech_tuning.html


Push rod : Yes, i use stock size of pushrod, but hardener pushrod, who was perfect before stroker
I done the head job, but no decked the head or the block (so no change on the geometry)

Valve : Stock valve, i just done a small lapping valve, i wasnt think it will be able to change valve geometry
I just order the tools for check push rod length

Spring : I have a friend who have the tools to control the pressure, but a +100miles from me

Thank for your seat pressure reference (170-180)

My plans :
- Change all my spark plug for new one (i have a set of TR6, 1 point hotter that i use now, but NEW in the box)
- Change my tune (put the timing at the super safe starting tune, something like 14 degree)
- Check my AFR with a new log
- Order new belt at correct size for my new pulley
- Order check push rod length tools
- Try to check my spring

inspector12

Good starting point. I would just start looking at all the simple stuff like your doing. GL!

Steve@C56

NEWS !!!

After changing my spark plug for new one (my 1 degree colder that the TR6 was completly black, without extrem rich afr)
After changing my tune (have try with super safe starting tune at 11 degree... b u l l s h i t, run like a crap, so i have take the base of the tune who made me hit 11.133s on a airfield... much better)
After check my AFR with a new log (again a little too rich => have correct the tune for tomorrow ^^)
AND after change dump valve position... (was in "hard" position, have put it in half position)
Car ran much better at high rpm ^^ (have hit +7200, freaking in street tire !!!)

Now, i think having belt slip because i'm not as fast as before stroker on a 4500-7200rpm in 2 or 3 gear (and engine running rich)

Have some code also since today :
p0704 : Clutch Switch Circuit ???
c1281 : Steering Sensor Uncorrelated Malfunction
c1288
... and i dont have cruise control
so, have to ckeck all wire and sensor in this area (had change master clutch for the tick, so...)

- HD Belt order done
- Check push rod length Tools order done
- And BAP order done (40A 20V model)

Also, i have to put on the radiator cover for force fresh air on IC and air filter who can explain not having all the power i expect

(and finally, think to try to check my spring... but think only)