Need some engine advice....

[PRHeads]

Also on the dyno they usually are getting nice cool air, that may also be part of the problem.

This is a very real thing.
Most guys aren’t running the motor on the dyno at 190* water temp...... or with the air inlet temps that can easily be over 100* in the vehicle.
Which can have a very real impact on what the “real world” octane requirements will be.

The other thing no one has touched on in this thread is....... the dynamic efficiency on the motor at WOT, in the rpm range where the pinging is occurring.
For example, it you removed the 4bbl carb and installed a tiny 2bbl, at WOT the VE would drop way down, and so would the cylinder pressure....... and the octane requirement.
Along the same lines would be heads that didn’t flow as good, or a more restrictive intake manifold.

Some of the things that make more power, do so by improving cylinder filling...... which increases cylinder pressure...... which can push up the octane requirement.

In other words, “by the math”, you could have two motors with the same CR, and calculated dynamic CR, with the same quench, cam profile, etc....... and have one run on lower octane fuel, if the induction is restricted, and the running dynamic efficiency is lower.
Of course........ it would also make less power as a result.

Assuming the info on the build sheet is correct, and adjusting a few specifics to end up at just under 10:1CR....... the dynamic CR ends up at just barely under 8:1....... which is the theoretical tipping point for premium pump gas.
So....... maybe it would be fine in a place that 93 was still available, and the 91 just doesn’t get it done.

I don’t know if E10 93 is available where the OP is, and that the 91 is the non-ethanol stuff.
We have both of those here, and I have a late model muscle car........ and it seems a little sharper on the 93 E10.
Keep in mind that new cars are constantly monitoring for ping, and adjusting the timing for peak performance.
So, I just assume the 93 runs a little better because it allows the computer to get more aggressive with the tune.

 

[451Mopar]

Sort of went over the IAT. He said he has a ramcharger type fresh air system?
The ICON Dished pistons are 24cc dish.

The 505" 440 I built with the Trick Flow 240 heads had 27cc dish pistons for 9.9:1 compression.
Used a solid roller about the same duration. Lunati Voodoo #40230732 That is 243/249 duration @ 0.050" lift. 0.578"/0.585" lift @ 1.5:1 Ratio.
Used the recommended Harlan Sharpe rockers in the 1.6:1 ratio, so theoretical lift (zero lash) would have been 0.6165"/0.624" lift @ 1.6:1 ratio. Used the trick flow heads with the solid roller valve springs and Ti retainers.
Engine ran fine on pump gas, but because of altitude, cranking pressure was about 130 psi.

 

[PRHeads]

OP’s build sheet says custom CP piston....... so we don’t really know what that is for volume.

I’d try running a 160* high flow t-stat, see if it had any effect.

As for the inlet temps....... most dyno rooms aren’t going to simulate the environment of a typical engine bay very well. So even if the air inlet temps at the carb are somewhat normal(fresh air hood), the heat soak of the intake manifold that takes place with the engine being under the hood, and with super heated air blowing on it...... the temp of the air entering the cylinder is going to be higher when the motor is in the car vs on the dyno.

 

[PRHeads]

Looks like you have a .080 mls gasket. (List shows .090 piston-to-head, with pistons .010 in the hole).
On a side note...it makes one wonder if the problem would still be happening at 9.9 if there was some quench.

I didn’t catch this until now.
Just assumed it was built with proper quench.

I have to believe it’s a contributing factor.

 

[33 IMP]

It would be interesting someday to compare a car with a flat hood, and uncoated headers, maybe 150° f under the hood, to that same car with a good cool fresh air system and coated (cooler) headers, maybe 70°f ambient. I wonder what the %power increase might be?

 

[33 IMP]

Since according to the build sheet, the quench is gone already, i decided to play around with some head gasket variations on wallace's compression ratio calculator. With the given 4.350 bore, 4.15 stroke, 76cc heads, 080 cometic gasket (4.38 gasket bore, according to summit), and a .010 deck, i came up with a flat top with 10cc of valve relief, and 2cc of other space (around the outside of the piston, above the rings), to reach 10.0-1. Mind you, this is a guess as to the piston.
With a .120 thick cometic from summit, with a specified 4.35 gasket bore , compression would drop to 9.3-1. With a similar .140/4.35 cometic gasket, it would drop to 9-1 (actually 8.98). There are also other thicknesses available.
Cometics aren't cheap, but i think that is the direction i would go, since the deck and head must be smooth enough to run the mls's that are in it now. If tuning can't solve the problem without killing a bunch of power.

 

[PRHeads]

I agree.
There is already no effective quench at .090” p/h clearance, so it’s not like the thicker gaskets kill that off.

You’d just end up with a lower CR.

I have a customer in Ok who has put together a few 505’s in the last year or so.
Prepped RPM heads milled to 78-80 cc, Icon inverted dome pistons, small-ish SFT cams....... sometimes headers, sometimes not........ good quench.
They run just fine on the 91 available there.

They’re probably a little shy on power compared to the OP’s 595hp.
Especially the ones with the ex manifolds.

 

[hunt2elk]

Assuming the info on the build sheet is correct, and adjusting a few specifics to end up at just under 10:1CR....... the dynamic CR ends up at just barely under 8:1....... which is the theoretical tipping point for premium pump gas.
So....... maybe it would be fine in a place that 93 was still available, and the 91 just doesn’t get it done.

I don’t know if E10 93 is available where the OP is, and that the 91 is the non-ethanol stuff.
We have both of those here, and I have a late model muscle car........ and it seems a little sharper on the 93 E10.
Keep in mind that new cars are constantly monitoring for ping, and adjusting the timing for peak performance.
So, I just assume the 93 runs a little better because it allows the computer to get more aggressive with the tune.

Wish we had 93 around here, but unfortunately we don't. There are quite a few stations that sell 91 octane non ethanol however.

 

[hunt2elk]

Sort of went over the IAT. He said he has a ramcharger type fresh air system?
The ICON Dished pistons are 24cc dish.

The 505" 440 I built with the Trick Flow 240 heads had 27cc dish pistons for 9.9:1 compression.
Used a solid roller about the same duration. Lunati Voodoo #40230732 That is 243/249 duration @ 0.050" lift. 0.578"/0.585" lift @ 1.5:1 Ratio.
Used the recommended Harlan Sharpe rockers in the 1.6:1 ratio, so theoretical lift (zero lash) would have been 0.6165"/0.624" lift @ 1.6:1 ratio. Used the trick flow heads with the solid roller valve springs and Ti retainers.
Engine ran fine on pump gas, but because of altitude, cranking pressure was about 130 psi.

Sounds like I have to move out to CO to get this motor to run decent. The wife would love that also as we could be near our 2 young granddaughters.

 

[Kern Dog]

Yeah, but how is the C H E E S E in Colorado ?

 

[hunt2elk]

OP’s build sheet says custom CP piston....... so we don’t really know what that is for volume.

I’d try running a 160* high flow t-stat, see if it had any effect.

Got a call into the guy who built the engine and hoping to hear back from him today. I will find out if the pistons are flat or dish and the cc value as well as verify that the head gasket is .080".
Somebody else mentioned trying a 160 stat to see if it made a difference also. I have a 180 in there now. When I asked the builder about that, he said he would want me to try a 190 or 195 and never a 160. The motor runs at 190 all the time now, so he thinks it would open and close more at the higher temp. DOn't really know what good that would do?

 

[hunt2elk]

Yeah, but how is the C H E E S E in Colorado ?

Lol. Pretty much non existent, fresh stuff anyway. Its funny that every time they come to visit, our son in law who is from Denver heads straight to a cheese house and loads up. Says there is nothing better than the fresh squeaky curds. He eats so much of the stuff that our daughter says he doesn't sit on the throne for several days afterward because he is so plugged up.

 

[hunt2elk]

Well, I tried calling Brian Hafliger @ IMM Engines probably 10 times yesterday. Got through to his helper twice and was told I would get a call back, but never did. Sent an email also with no response.
I sure hope he proves me wrong, but I am starting to believe that he used up a bunch of parts he had sitting on his shelf to build this motor that won't run on pump gas. That would explain a .080" head gasket being used to try to compensate for flat top pistons (if that is actually what they are).
Like I stated earlier I don't know jack about engines but knew what power level I wanted and wanted to have no issues running on 91 octane gas. After he built a perfect motor for me a couple of years ago where the whole process went as smooth as silk, I didn't hesitate to go with him again. This entire build has been a **** show. Did I mention that I gave him $13,700 for a motor that won't run on pump gas?
As of now after hearing what you guys are thinking as well as a buddies input, sounds like I need a different cam, thinner head gaskets, and dished pistons?

 

[451Mopar]

I did not know the head gasket was 0.080". Each 0.020" of head gasket thickness is about 5cc volume.
If the pistons are flat top with 7cc valve reliefs, the compression ratio would be about 10.4:1 with the 0.080" head gasket.
with a 0.120" head gasket compression would be 9.6:1

FWIW, Dealing with an engine that has too high a compression ratio is alot easier than starting with one with too low a compression ratio.

 

[PRHeads]

Somebody else mentioned trying a 160 stat to see if it made a difference also. I have a 180 in there now. When I asked the builder about that, he said he would want me to try a 190 or 195 and never a 160.

Didn’t you already say it doesn’t ping when the motor is cold?
Just think about that, and what affect lowering the operating temp might have on the ping.

There’s a reason a lot of “kits”(cold air, tuners, etc) to hop up late model muscle cars include a lower temp t-stat as part of the kit, or have it as part of the recommendations for best performance.

 

[Curiousyellow71]

You could run a water/methanol injection kit that comes on when you floor it. Probably the easiest and most affordable fix. Since it drives fine under normal driving it seems like a good fit.
https://www.snowperformance.eu/en
Pistons must have some dish then to get it to 9.9...I don't know why they didn't do a bigger dish to get the static compression 9.9 with quench...especially if it was a custom piston...kind of sounds like a oops.
Spending that much money and having one part wrong stinks. I wouldn't be real happy either..but I'd say you have several options to get it right.
1. Thinner head gaskets and different pistons should work with the cam you have but get it to 0 deck w quench and a dish...I would suggest you go a little less compression then 9.9:1 and do it all with your new pistons.
2. Like 451mopar mentioned Cometic makes good options for lower the compression. The thicker gasket can get pricey...but still cheaper and your surest path 2 making your present components to work. Keep the cam and pistons drop it down to 9.5:1 or less. Quench is probably good for a few hp and so is a .5 of compression but probably not that much in reality.
3. A cam change alone on a street engine you probably wouldn't be real happy, and it may not get the job done with the high flowing trick flows. Probably have to lower dcr a half point. The custom cam you have has a wide lsa and fair sized duration to work w pump gas already.

 

[dvw]

If you requested a pump gas motor what does the engine builder say? I cant see 180psi ever running on pump gas.
Doug

 

[HEMI-ITIS]

Somebody correct me if I'm wrong, but I believe w/m only drops IAT 30/40*. Can anyone verify that??

 

[dadsbee]

Only drive it in the rain with the scoops open Joel! Free water injection.

Hope you get it sorted out, sounds like a lot of good knowledge here helping you forward... while your engine builder hides.

 

[Curiousyellow71]

Somebody correct me if I'm wrong, but I believe w/m only drops IAT 30/40*. Can anyone verify that??

30 with a little and 50 degrees with a lot. For the detonation problems described that runs fine cold and starts to show up when the secondaries kick in...30 degrees should be a big difference. Could probably even run on 89. Not 2 many people do it without boost N/A works but less common.