who has the highest CR on 60*?

[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]

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]

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.

[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...

[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.

[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]

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.

[no_doz]

this is so off topic atm but im eating up all this theoretical discussion as i eagerly await a high number from someone.

is anyone running a 3.1 or 3100 with the iron head pistons & the iron head-head gaskets right now?

[ForcedFirebird]

this is so off topic atm but im eating up all this theoretical discussion as i eagerly await a high number from someone.

is anyone running a 3.1 or 3100 with the iron head pistons & the iron head-head gaskets right now?

There are quite a few f-bodies with that combination I sell parts to them all the time...

11.5:1 or so pump gas 3.4/3500's

[no_doz]

if you wanted to push 12:1 or 12.5:1 would a cam regrind be a necessity & if so what aspects would be beneficial to change as far as the cam goes?

[Superdave]

One of the domesticcrew guys was running a 3x00 hybrid with iron head pistons, 3400 heads and a H272-2 cam. I don't remember how fast it was but it did run.

most of those guys have moved on in the last several years though.

[stevalier]

Im running 11:5:1, on 94 octane, still need a chip for it

[torq455]

i believe Lorenzo had a 3400 running on a 12.5 CR, but it was beating up the bearings.

[ForcedFirebird]

I agree with the others' I have conversed with. It's not the compression that makes the bearings look like punch-tapes, but rather knock. People rely too much on a knock sensor IMHO, for the simple fact that once the ECM has read the knock-retard, the event has already happened. It is in place as a safety feature more so than a tuning tool.

[pocket-rocket]

for the simple fact that once the ECM has read the knock-retard

That poor kid. People are always saying he is a bad egg