Ryan00TJ

With the Whipple Stage 2 and 120 T stat mine runs 140-145* at speed and high 140's at idle. Even though my rev limiter is 5450, there is no reason to go past 5200 with stock internal/induction. No power to be made spinning higher. There is a very noticeable midrange power gain vs stock. While the power gain at WOT is not as pronounced as thru the midrange, it's noticeable and the engine revs much cleaner. I ran it pretty hard at times this summer with not a hiccup. Most time was 93 octane but there were times over the weekend I used marina 89 octane. No knock present when engine scanned.

Thought this was interesting quote from Raylar.... Even though I've always had great success with Mahle's 4032 pistons in previous builds when tuned right. IMHO, the piston and ring setup was fine for your power level. Your previous 300ish hours of runtime proved that. Is the ring gap on the tight side? Probably. With a critical loss of FP like you had, it's all speculation as to what could or would have held up when it detonated.

Rage

Bob,

Thanks a ton for the invitation! I surely will take you up on that offer. I imagine your Cobra build will be complete by the time the engine is ready to run. I am having shoulder rotator cuff repair surgery Dec 4.and decided not to try to accomplish the rebuild before then since I am pretty much a one armed bandit already. With a six week immobilization then a couple months rehab the plan is to start the rebuild in March. I am pissed that it has to wait till then but resigned to that fact. Looking forward to the visit. Thanks again!

SB

^^^Awesome.

So, no one 'liked' BOBL's post #39 ?

Give him a big fat kiss and a 'Like.' LOL.

That is crazy good !

nonstop

I know I'm late to the thread but I just went through the same piston issue with my blown bbc (#8 cyl) and hurt a few others. Fuel pressure dropped to 3.5 lbs on wot . (had no fuel pressure gauge in dash/ there is one now). Also I found out my plugs were 2 heat ranges to warm. Had ngk6 and now run ngk9 just to be safe. Back to running like a champ. Maybe you increased cyl pressure with your new cam set up enough to cause an issue with the plugs? Just a thought....

bobl

I'll throw another thought into the mix. I've always felt 32+ degrees of timing was too much for those fast burn heads. Maybe your engine changes, lost fuel pressure, etc. was enough to push it over the edge. I would love to see some dyno runs with the timing pulled back a couple of degrees. I bet it wouldn't lose any power.

FYI, have done some tuning on Volvo 8.1's with the mefi 4. I can tell you for a fact the stock HO does not like advancing the timing beyond about 28, degrees. You can read the knock retard on the mefi 4 and any timing you added it would pull it right back out.

Bob

Rage

Thanks Bob. The 32* originally came from the GM HP3 Gen1 engine which I initially copied along with the 12.8 AFR WOT on 87 octane that produced max HP per Innovation Marine. Of course that engine was 515hp at 5400 rpm and way different than what I am running now so yeah maybe time to back off the timing at WOT. The different Volvo experience could be related to it's cam maybe having more dynamic compression than the HP3 Gen1 cam. I know my stock 425hp 496HO had 175 psi compression and the HP3 Gen 1 was around 160 psi I think.

bobl

Could very well be. That is one of the big advantages of tuning an engine on the dyno. You can find the best timing for a particular combination I'll generally chase the HP until it shows no gains, then back up from there. Of course with the PCM you don't really have that option since you have to ship it off for tuning. My personal opinion(for whatever that's worth) is that combustion chamber design impacts timing requirements more than any other element in a build. Compression will affect the octane requirements but timing required for peak HP would not change significantly with changes in compression or camshaft.

Raylar

AFR map from our tuner on a stage 1 540 build. If possible, you should be somewhere in the 12.2-12.7 range at WOT. In street vehicles, we've found that a lean cruise is fine at 14.0-14.5, but as soon as you dip into the throttle, power enrichment or the tuning should add more fuel to prevent a lean condition.

Here's a dyno from one of our old 600s which should be a pretty similar setup to yours:

sutphen 30

Raylar,thats what I've told him about afr's,not sure he has the tuning capabilities of the 555 computer.also told him to look at his knock sensors to see if he has too much timing.
Raylar,what timing (max) are you running in your 540's?

SDFever

Larry,

Don't forget that with a 13.5 and above 'lean cruz' we burn one up cause "lean doesn't care how fast you're going". There's a big pull on boat engines from getting on plane and above. You might be able to skate by once or so with really good gas and lucky day but anything over 12.8 is pushin' it unless you're just at fast idle and below.

We've spent tons of time and money on the 555. Spend the time and hang a Holley or something else you like on there. Unless you are rich enough to have one of the experienced tuners ride in your boat etc, it's just not worth it anymore to expect too much from that box.

Keith, yes changing the fuel pressure is a fairly decent band-aid up to a point but at Rage's level or something like that it's not even worth thinking about and there are a lot of issues going on at same time.

We just finished a 588 with raylar heads and 105mm. Going up 3 injector sizes (62LB) the duty cycle is 70%. Haven't had time to fully digest all the recent info but i went pretty far on the stock merc injectors (42LB) and prob could have upgraded a long time ago. This is a very dynamic conversation and you gotta take it all piece by piece with the changes and the equipment being used etc. There's a difference in AFR sensors, equip etc. IOE, if you are using a bosch type sensor with the Innovate hand-held then i'd recomend setting it almost one point richer compared to say an NTK in a nice, dry envirionment.

If you stay at Larry's 600hp level kit, then his instructions and stuff works really nice. If you use that same product and go further, it becomes a slide ruler on steriods. You really need an open EFI system that you can learn and tune. ...And it starts all over..