[CL10473]

Anyone know if the cylinder heads on the 4Bt and ISB 3.9 can be swapped?

Thanks.

 

[Bretticus]

thats exactly what I am looking into.. I believe so.. the engine is a 4bt motor just like the 6isb is a 24 valve head onto a 6bt.. sooooo.. logic would dictate the answer to be yes.. let me know what you find out.. I am estremely interested in this as well and also want to know the perfomance gains from it..

 

[CL10473]

Cool. I'll keep searching around. I know it was done on a diesel dragster that was featured in Diesel Power a few months back.

 

[Diesel Durango]

what are the advantages? doesn't seem like a cheap way to go...

 

[CL10473]

I'd assume power. But I don't know for sure. Its more curiosity than any thing else right now...
I agree on it not being cheap. It would be nice if you could just chop a dodge head...

 

[Dougal]

what are the advantages? doesn't seem like a cheap way to go...

Mainly a centered injector.
What that means for fuel economy I'm not sure, maybe someone can pull up the factory power/torque/bsfc curve.

I'd also expect better VE at higher rpm, but not really a problem with the revs these puppies run.

 

[rotty]

4 valves head usually flows more air.
But, you can't just exchange with a 2 valve head w/o changing pistons as 2 valve heads have offset bowl pistons.

 

[Bretticus]

true 4 valve cylinder head has the advantages of lower recipricating weight so the engine can gain higher rpms without floating the valves.. also they would stagger the valves just slightly giving it a better swirl in the cylinder gaining efficiency. With this setup though, you push 2 valves with one pushrod so your recipricating weight stays almost the same but you still gain some efficiency from added valve area and the injectors going to the center of the cylinder..

How much this would help this engine I would really be interested to see..

 

[57 napco]

16 valve heads are common rail. The injectors that fit the head will not work with a regular pump. Also the intake plentum is cast larger and would not clear the injection pump. You would need custom injectors and machine the intake off and build a new one. Don't forget custom fuel lines. Nothing several K could not overcome.

 

[afgunn]

I was hoping they would fit but, I believe 57 napco knows from where he speaks. Drat! Oh, well, saved me a K or 2 there. The link below has detailed info year by year for the cummins 5.9 which should apply to the 3.9 except for the year that the improvements were actually made. The engineering and improvements should still apply.

http://dodgeram.org/tech/dsl/Facts/epa_changes.htm

 

[Mallo986]

12/24 valve heads

The reason Cummins went to 4 valves per cylinder was driven by Emissions only... facts are you can flow much more air with 2 valves per cylinder than with 4... as for BSFC...I can get any data sheet you want..

 

[Machman]

The reason Cummins went to 4 valves per cylinder was driven by Emissions only... facts are you can flow much more air with 2 valves per cylinder than with 4... as for BSFC...I can get any data sheet you want..

I'd like to have the one for CPL 857..

In fact, a data sheet thread might be an idea. I've seen only 2 data sheets for the 4BT and one for 6BT here or on the Yahoo group's files section. Or did I miss them?

Anyway, might be interesting for comparison among the automotive use engines..

 

[g_dawlton]

The reason Cummins went to 4 valves per cylinder was driven by Emissions only... facts are you can flow much more air with 2 valves per cylinder than with 4... as for BSFC...I can get any data sheet you want..

Meaning absolutely no disrespect to Mallo986, but the claim that 2 valve cylinder heads can flow much more air than 4 valve cylinder heads is false. All of the reading I've done suggests that comparable 4 valve/cylinder heads flow far better. As an example, when performance camshaft manufacturers started to manufacture after market cams for those engines with 4 valves per cylinder they attempted to use what had worked with 2 valve heads (ie lotsa lift and long duration) but they found that the 4 valve heads wanted far less lift and duration than 2 valve heads. 2 small intake valves (so too with 2 small exhaust valves) have far greater seat area than 1 large valve does. Same should hold true if turbo charged.

 

[deere country]

Well 4 valve heads may flow better in some applications, like gas engines but when talking 2 valve and 4 valve cummins b series heads the two valve head flows better hands down. Think about what you stated regarding cam lift, how do you move more air into the cylinder head when its open for a much shorter time. This may be true in a naturally aspirated engine, like a gasoline but not turboed diesels

 

[Mallo986]

2/4 valve

I based my comment on flow from actual flow bench data and from Techs at Cummins factory..I'll take my 2 vavle anyday....especially after it was flow testedbefore and after mods......might have something to do with two turbos, high boost..

 

[JakeDiesel]

Yes I would like to see the data sheet. I always thought that 4v pre cyl would = better flow.

 

[mastermoparman]

hmmm 16 valve 4bt....

i have herd a few guy say with the 6bt that if you use the 24 valve head and pistons on a 12 valve block(mec fule pump) the were getting diecent power and economy with the improved flow. im not shure how they had the injector hooked to the fuel pump but i wonder if it could be done on a 4bt

 

[JakeDiesel]

You can get injector lines at haisleymachine.com or some other high preformance sites.