who has the highest CR on 60*?

[sprucegagt]

I believe the head is billet steel. Aluminum won't handle the repeated thermal shocks. I know the stock cast iron heads will only last maybe 2 seasons before needing to be replaced due to cracks.

[ForcedFirebird]

Considering that a custom made CNC head costs over $10,000, few are willing to go that route. That's per head cost. Mack's use a V8, Cummins inline 6 and few of these guys have any kind of sponsorship.

Yeah, then add the cost of the truck, multiple turbos, drivetrain etc. I know they are bling!

$10k sounds a lot for a CNC'd head though... Maybe that includes the cost of the die for the rough casting?

[sprucegagt]

They weren't exactly discussing the hydrolocking in the thread, but rather the rod integrity. I found it fascinating that they were bending rods due to the amount of fuel needed.

I can understand the blocks splitting, but was that a stock-block class in particular? A CNC'd block designed around the kind of stress they are creating might be impervious to said abuse.

Considering that a custom made CNC head costs over $10,000, few are willing to go that route. That's per head cost. Mack's use a V8, Cummins inline 6 and few of these guys have any kind of sponsorship.

[robertisaar]

A CNC'd block designed around the kind of stress they are creating might be impervious to said abuse.

looking for a new type of customer, john?

"bending rods due to the amount of fuel needed"

pretty much the defitnition of hydrolocking: so much liquid(of any type) in the bore, piston tries to squeeze it, and the rod gives up the ghost...

[ForcedFirebird]

They weren't exactly discussing the hydrolocking in the thread, but rather the rod integrity. I found it fascinating that they were bending rods due to the amount of fuel needed.

I can understand the blocks splitting, but was that a stock-block class in particular? A CNC'd block designed around the kind of stress they are creating might be impervious to said abuse.

[sprucegagt]

I know what your talking about, but different pulling organizations have different rules. Ask those guys on speedtalk what's the bigger problem. Hydrolocking or compromised block integrity due to boost pressure (brought on from too much RPM). This is what's regularly around here.

http://www.hotrodsemis.com/

Here's a link to their rulebook. It has no limit for boost pressure, but it does limit you to 2 air stages. Their rules start on page 41.

http://media.propulling.com/pdf/ppl-...-5-19-2009.pdf

[ForcedFirebird]

No offense, but their is a little mis-information here. Those semi's can be multiple or usually single turbo, but either way run over 100+ PSI. There big hold up is getting enough fuel (injection pump limitations) or running too much boost for the block. The block will split length wise at the cam bore. Hydrolock is much more likely in a Top Fuel Nitro dragster.

Look it up The guys on speedtalk have some of these engines and they run right at the sanctioned limit of 6BAR if memory serves me correctly.

http://www.youtube.com/watch?v=s_9vGZtdJD4

I am talking about pro tractor pulls.

[sprucegagt]

The quad turbo semi's that are built to do the tractor pulls are running about 100psi, on top of the 16 or 18:1 compression. They are running SO much boost that they are constantly on the threshold of hydro-locking the engine because they need that much fuel to compensate all the air going in and maintain a 12.5:1 AFR. Air compresses, liquid fuel doesn't

No offense, but their is a little mis-information here. Those semi's can be multiple or usually single turbo, but either way run over 100+ PSI. There big hold up is getting enough fuel (injection pump limitations) or running too much boost for the block. The block will split length wise at the cam bore. Hydrolock is much more likely in a Top Fuel Nitro dragster.

[geoffinbc]

Diesels don't knock, or detonate. Fuel is not in the cylinder until the very last part of the compression stroke. No engine can withstand constant detonation. Think of the diesel injector like a spark plug. It will inject fuel several degrees before TDC just like a spark plug sparks before TDC. But never so much that the pressure causes detonation. Remember fuel takes time to burn so you must initiate a flame before TDC so when you do reach TDC the full burn is on and real power can be made. This is why Direct Injection gas engine have the ability to run boost coupled with very high compression. There is no fuel in the cylinder until the very end of the compression stroke. So there is no risk of fuel burning early and essentially trying to run the engine backwards.

[ssdurango]

Hey I'm the guy with the propane 3.4. I had It at 11:1 with 12 psi boost running straight propane. A ring land broke on the dyno, could of just been a weak casting. So I've been running around at 9:1 at 12 psi this summer.

I'm also a diesel mechanic. The knock in diesels is due to late or early combustion on the power stroke caused by low ambient tempurature or poor injection timing.

[MMGT1]

Would that give us an estimate? Figure Im around 10.5 or so right now, but I really dont know.

[ForcedFirebird]

Cranking pressure doesn't always relate directly to static compression.

[MMGT1]

Mine was pretty strange. When the block was replaced a couple of weeks ago, Milzy tested it before the install and we got 180 arcoss all cyclinders. Tested it again last week and got 205-210 straight across(1500kms on build). I have no idea how to convert that, anyone know what I'd be sitting at?..... curious

[robertisaar]

diesels don't resist knock. they are built heavy to take it. that's why they are so noisy.

i guess i should rephrase that:

diesel's ability to not blow the fuck up into 5000 different pieces due to knock is awesome.

[ForcedFirebird]

The quad turbo semi's that are built to do the tractor pulls are running about 100psi, on top of the 16 or 18:1 compression. They are running SO much boost that they are constantly on the threshold of hydro-locking the engine because they need that much fuel to compensate all the air going in and maintain a 12.5:1 AFR. Air compresses, liquid fuel doesn't