Lucas1

How does the 145* vs 155* spray pattern affect head gasket choices?

stock/ .10 /.20 over gaskets on stock head(not planed)

will the .10 over gasket i have affect more then cold weather starts?

should i get the head shaved .10 when doing the o-rings? and how will that affect the valves?ie clearance and fit..


my truck will FINALLY be coming out of the body shop.
tunning the twins and getting it running right..then the head comes off.

i dont even know what its like to drive my truck anymore.

Tate

Spray angle is more dependent upon piston design than head gasket thickness. The thicker the gasket, the less timing you can run to keep it in the bowl. That being said, there are worse things to consider. Lower compression will cause harder starts, more haze and be less responsive. But if you go .010" thicker, you're only looking at a 0.5:1 drop in compression ratio. 12v is 17:1 stock, so you'd look at 16.5:1. Stock SO 24v is 16.3:1, so its still well in the acceptable range.

I wouldn't shave the head more than needed to make it flat. 0.010" off shouldn't cause any issues though. Mine was cut .008", run the stock thickness gasket, and its been running just fine. I haven't pulled the head to see if there are valve marks in it, but its spun 4500 rpm and been good. So you should have ample piston to valve clearance.

Lucas1

i know this is beginner talk but school me....i have no time for the search button.


how are the 12V VE piston bowls shaped compared to a 24V and 12V p-pump and common rail?

like for example a 155 spray pattern with a .020 gasket cause the injectors to wash the sidewall more creating haze poor "burn"

now is it the standard to use marine nozzles.

like why do i see 155 spray pattern..

i believe my SDX'x are as well as DDP's


i never hear anyone having to install thicker gasket or doing other changes when wanting increase rpm.

hypothedicaly speaking.

when or if i p-pump this thing down the road. i just want to know what iam expecting.


just a topic of conversation.

i gots no more money

dvst8r

Unless you have had your block severely decked, I see no reason for the thicker hg.

Piston design is dramatic between all of the pistons you have listed. If I was at home and not posting from a hotel room, I could take pics of all of them for you. I think if you search on compd someone along the way has posted pics of all of them.

Thin hg, thin washers under the injectors, and bump a tooth on the timing. Should be nice and lively.

Mike Holmen

Just like Tate said, its all dependant on the piston bowl design. VE pistons is more open bowl than a 12V 215HP bowl. Spray angles affect how much timing you can run. I would run the thin shim on the injector to keep the spray inside the bowl. The VE piston you probably can run more timing than the 215 piston.

VP piston is a center fire injector, the 12V injectors come in at an angle, but fire evening into the bowl. The 12V bowl is slightly off set vs the VP piston.

Trust me this isn't beginner stuff. You can try to run the VP piston with the 12V head, it just might not make as much power or run very well. I'm trying a few different 6.7L piston bowls just to see which one make the most power for my injector angles. Found three different piston bowls that are available.

The 155 deg spray injectors are good to be used with the newer pistons like the 5.9L 03/04 and 4.5-07 CR piston bowls. Not sure why you selected VP pistons, they cost the most for 5.9L and have a smaller bowl than the CR stuff. 4.5-07 pistons are the cheapest 24V piston going.

The 4.5-07 mono-therm piston bowl are the one to buy, but the cast rings are a pain to install.

Mike Holmen

Here is dimensions for CR pistons bowls. I don't have any dimensions for VE 12V or 24V VP pistons.

Tate

From the master.
http://s358.photobucket.com/albums/o...Piston%20Info/

Lucas1

i knew there were some differences between pistons on differently pumped trucks. did not know there was a possibility between 215hp pump vs 160 .

my pistons are stock VE and i was thinking about this the other day as i have a .010 over head gasket to replace the weaping one in my truck.

i purchased the oversized gasket because i was told with higher boost ie twins the lowered compression ratio would help with cylinder pressure and the negative affects are minimal.(hard cold starts)

obviously the positive affects are minimal as well.

but with the thought or 155 spray vs the 145* stock angle combined with the oversized gasket i thought perhaps i would see a difference .
mostly with low boost smoke levels............and i dont want that

iam only assuming my head doesn't need a plane,ill just run the .010.


what is 12V storm???
man not sure what the piston inner degree does for performance/efficency.

the changes up to 6.7L MUST be for performance correct?
so a common rail piston in a 12v would be an upgrade.????
but dependes on the head design i guess

my head hurts


and how does spraying it with propane/nitrous/watermeth change what choise of bowl

and

THANKS FOR THE REPLY"S THIS IS THE MOST ACTIVE INTERESTING SECTION ON THE BOARD

Tate

I wouldn't lower your compression for a daily driven application. Just not enough benefit. I've run 80 psi on factory gasket w/o-rings on my 12v. Not sure what the 24v was, but I'm sure it was in the 110 psi range. Stock gasket w/o-rings.

12v STORM would be the late '97 and '98 12v engines. Same block as the 24v's, which is a STORM block.

I wouldn't bother running a CR piston with a 12v head. Especially the 325hp pistons. Lack of meat around the top ring land make for an easy piston to melt. While that issue would likely not be as much of an issue with a p-pump application, its still not optimized for a 12v head with offset injector. The non-re-entrant bowl is designed for a 124 degree cone angle nozzle. 12v injectors are usually in the 145-155 range.

The non-IC 1st gen pistons are the closest to a centered bowl style piston, I'd look at those.

Lucas1

should i return my .010 over gasket for a stocker or plane the head .o10(might need it anyway)


or just run it.?

m

dvst8r

I would run a stock gasket even if you do plane it.

Lucas1

and piston /valve clearance is not an issue?
depends on the plane i guess.

if this thing ever see's a p pump and high rpm i wouldn't want trouble

Mike Holmen

Heard a few engine making some decent power running the CR piston bowl and the 155 degree angle injectors.

My guess is that injector not firing in the piston CR bowl middle using a 12V head will hurt power.

jtamulonis

STORM = Straight Thread, "O" ring, Metric . all the threads in the water jacket and oil galleries are straight threads and NOT tapered pipe threads. they use an "O" ring to seal the metric threads.

Mike Holmen

best way is to measure the valve to piston clearance. Most cam manufacturer's have a specs for the intake and exhaust side. Most engines have around 24 thou piston protrusion from the engine block. Machining the head surface, doesn't change how much piston protrusion. If the valves are sunk into the head, then machining the head surface, the valve would closer to the head surface, but then you might have weaker valve spring seat pressure.

For street trucks 16.5 to 17.3 compression is what works best.