FI 403 wont pull past 5500 RPM?

[b727pic]

Hi Guys,

This one has me stumped, need all the help I can get please.

Background: car is a 2004 M6 GTO with a Procharged (P1SC-1) 403CI. Custom CNC AFR 235 heads by Ed Curtis, Ed Curtis cam 224/232 .600/.600 114LSA, Wiseco coated pistons 9.25:1 SCR, Rhoads lifters,Callies crank, Compstar rods, LS6 intake, TR 6 plugs gapped to .035, New firecore 50 plug wires, Devils own Meth, squirting a 75% meth mix through 1 7GPH and 1 3GPH nozzle, with an additional 1 GPH nozzle precompressor, JBA shortie headers, flowing thru catless mids and a 2.5" Magnaflow exhaust.

My issue is that I can't seem to get any power beyond 5500RPM? I had similar issues with my old 408 setup which did share several components above...ie Crank, Rods, Cam, Lifters, all engine sensors etc....

With the new 403 installed I took the car to Dynamic Tuning Solutions...AKA EC_tune AKA Doug for the initial dyno break in and tune. Car only put out 450 HP and was really unhappy about reving much beyond the 5K mark. Took the car home ran a couple of diagnostics and found both Cats were blown Installed a pair of Catless mids (for tuning purposes) and started on a "street tune" all seemed well and good, seat of the pants and HP tuner logs looked great. having tuned all I could with 3rd gear "on ramp" pulls, we put it on a superflow dyno this morning. The results were disappointing, although I have gained 200HP from where Doug left off, I still am not getting any linear movement past 5500 RPM????? and no DTC's to help pinpoint any issues???

Today's first pull was just under 600 HP, I adjusted the meth controller to delay max Meth flow from 10PSI to 15PSI. This seemed to have helped as HP jumped to the best of the day 652 RWHP. My logged LC1 was showing 10.3 AFR while the tail pipe sniffer showed 10.5..I wouldn't think that was too rich to put the fire out in the holes....but maybe that is part of the issue?? I plan on turning the Meth off, putting the timing back in that Doug had initially and see if that at least lets the motor pull throughout the RPM range.

Given that I have similar issues with two different engines and completely different valvetrain top end...ie heads, springs, rockers etc. could it possibly be sensor or electronics related? could crank or cam shaft information be good up to a certain RPM then change???

In any case I am stumped, looking for all the help I can get. I hope this doesn't turn into a reluctor wheel issue next worse case would be the Rhoads lifters, anyone heard of those being an issue at RPM???

The attached files are the current tune and dyno scan.

[jakebdb56]

Might try doing away with the meth temporarily to see if that's causing some issues. Seems that once you lose power it's going really rich although yes meth will drop afr, but to rule something out it seems a simple start.

To me, it doesn't look sensor related at all since you're breaking up at around the same point at WOT. Sensor issues would likely cause issues elsewhere...

Load the default config, check to see if LTFT's are showing up. Just wondering since they aren't disabled in the tune although closed loop is disabled.

[Google]

zerro or maf hz table to start with.. change engine/airflow/dynamic high rpm disable to 12800rpm from 4000rpm... change P0101, 102, 103 from 2 no mil light to 0 on first error..

then retune your ve table and after see if it still stops at 5100rpm..

[b727pic]

After reviewing my old 408 graphs with the new 403 set up, it is interesting that although the 408 simply flatlined at 5500 vs the 403 dying then coming back up, it all seems to happen at the same HP level....650HP?

I am going to do one of two things here,

1) pulley up to 6 /7 PSI should bring the HP down approx 120-150 or so....
2) pull the belt and adjust whatever table need adjusting in the tune and do an NA run.

theory is that maybe those 1 5/8ths JBA primary's have simply maxed out?? an NA run would rule out all FI and Meth issues (if there are any). If the graph goes linear I guess I found the problem.

Other than adjusting PE and Boost tables, can I just leave the 2bar OLSD tune alone. Or am I gonna have to go back to a 1bar MAP sensor and related tuning?

[MikeGyver]

It seems to me that if you reached a point that the exhaust wouldn't let any more air through, then the boost would shoot up at that rpm, instead of continuing to increase linearly.

[Google]

whats is your ICL?

[edcmat-l1]

There's usually only two things that will cause a graph like that.

1, spark blow out from the gap being too big (or other things not pertaining to the LS platform necessarily)
2, valve springs. They tend to reach a point of harmonic they don't like, and then run through it.

Things like incorrect valve timing, an exhaust restriction, intake restriction etc, will almost always cause a flattening of the power curve instead of the harsh dip and recovery.

PS, I would run it significantly leaner, mid 11s, esp with the meth. I'd spray as much meth as I could, and pull the fueling out of the petrol (VE).

[LSxpwrdZ]

I agree, that looks like valve float to me. Also the AFR looked decent in the mid 11's up to 5500rpm and after that it richened up. Valve float will cause a richer mixture as well as a huge decrease in power. With boost there is more strain on valve springs with the pressure against the back of closed valves, assuming you have 2.08" intake valves that is roughly 3.3 sq.in. of surface area. With 15psi (204kpa in your log file) you are taking away nearly 50# of seat pressure from the valve spring.

Also you are running a P1SC head unit on a 403" motor that needs airflow! That P1 is probably maxxed out!

[Ls1c5vette]

I was also thinking valve float, same kinda thing happend on my buddies NA LS2 after a cam install and he had incorrect seat pressure, once changed it was night and day in the high rpms.

[roadconetuning]

springs...

[b727pic]

whats is your ICL?

Per Cam card
Recomended intake centerline: 112*
LSA: 114*

[b727pic]

There's usually only two things that will cause a graph like that.

1, spark blow out from the gap being too big (or other things not pertaining to the LS platform necessarily)
2, valve springs. They tend to reach a point of harmonic they don't like, and then run through it.

Things like incorrect valve timing, an exhaust restriction, intake restriction etc, will almost always cause a flattening of the power curve instead of the harsh dip and recovery..........

Interesting you say about "flattening". Here is my old 408 last dyno, keep in mind same cam, lifters and exhaust. Heads and associated items are different.

PS, I would run it significantly leaner, mid 11s, esp with the meth. I'd spray as much meth as I could, and pull the fueling out of the petrol (VE).

I agree, I wasn't totally commited to the meth in an effort to have a safety net should the meth system fail, I was letting it run rich at the upper end. I have since come to realize that I can't have my cake and eat it to

[b727pic]

I agree, that looks like valve float to me. Also the AFR looked decent in the mid 11's up to 5500rpm and after that it richened up. Valve float will cause a richer mixture as well as a huge decrease in power. With boost there is more strain on valve springs with the pressure against the back of closed valves, assuming you have 2.08" intake valves that is roughly 3.3 sq.in. of surface area. With 15psi (204kpa in your log file) you are taking away nearly 50# of seat pressure from the valve spring....

Here are the head setup details..I am pretty sure EDC has these setup correctly.

Intake runner CC 238
Exhaust runner CC 86

Intake valve brand and size: Ferrea 2.080
Exhaust valve brand and size: Ferrea 1.600

Spring brand: My PS4 Duals with titanium retainers
Spring loading: 155# on the seat at 1.820" installed height

Also you are running a P1SC head unit on a 403" motor that needs airflow! That P1 is probably maxxed out!

You are correct the head unit is maxed out, I am at max impeller speed at 6500 engine RPM.

If I am already at 14 PSI, I don't see the need for a bigger head unit. I would think more "airflow" is simply going to compound my existing issues, not resolve them.

However once all this is sorted out I do have an F1C sitting in the cabinet

[roadconetuning]

it also seems odd considering my buddy has a stock bottom end LS1 with LS6 heads, big cam and a P1SC that made 705 to the tire in his C5 Coupe...

[b727pic]

it also seems odd considering my buddy has a stock bottom end LS1 with LS6 heads, big cam and a P1SC that made 705 to the tire in his C5 Coupe...

how much boost and what was his exhaust setup??

[edcmat-l1]

It's not the exhaust, it's not the ICL. I would get a set of checker springs, and a valve spring mike, and do some checkin and see if you can't get a shim or two in there to tighten up the seat pressure. If you need specific details on how-to, you can call me at the shop today 757-468-5101. I'm busy as crap, so you'll probably have to leave a message and I'll call you back.

[b727pic]

It's not the exhaust, it's not the ICL. I would get a set of checker springs, and a valve spring mike, and do some checkin and see if you can't get a shim or two in there to tighten up the seat pressure. If you need specific details on how-to, you can call me at the shop today 757-468-5101. I'm busy as crap, so you'll probably have to leave a message and I'll call you back.

I am changing pullies today, most likely only result in 6 PSI or so. I was thinking if the power band became linear with this setup it would point to the exhaust. however you bring up a really good point about valve seat pressure. Assuming power does go linear at 6 psi, but not at 14 I guess I still have not pin pointed the issue.....but have narrowed it down

But to confuse matters, if you look at the 408 graph I posted, that was with the same cam, totally different heads and valve train. pretty much flatlined at the same point I am having issues now?

Thanks or the contact info, I will run a few more tests and post my findings. Pretty sure it will be after the Holdiay's before I get too much more done.

[jakebdb56]

Also another thing, is your crank pinned? Now that I remember we had a similar issue kinda with a friend's running a big pulley on the P1SC. The pulley spun on the topend since there was so much load on it trying to push the blower beyond it's efficiency range.

[b727pic]

Trying not to confuse matters, and making one change at a time. I swapped out pullies.

Old setup: 8" crank x 3.25 blower, 65,000 impeller RPM @ 6500 engine RPM
Yielded: 204 KPA / 14PSI

New setup: 7" crank x 4.25 blower, 43,500 impeller RPM @ 6500 engine RPM
yielded: 134.6 KPA (6400 RPM) / 5 PSI

I find it interesting that I lowered the blower impeller speed by 21,500 RPM, yet only lost 4.72 PSI of boost? I did speak with Procharger tech support, they concur that seems about right. I also forgot to factor in I do have a 1GPH meth nozzle pre compressor that may have added a .25-.5 PSI. At max impeller speed the meth spray accounted for 1PSI additional vs no spray.
__________________

[b727pic]

Also another thing, is your crank pinned? Now that I remember we had a similar issue kinda with a friend's running a big pulley on the P1SC. The pulley spun on the topend since there was so much load on it trying to push the blower beyond it's efficiency range.

Crank is Keyed...