110 heads

[skyhook]

Mike,
In dyno charts, you do some comparos that show 110" engines with BHP heads. Are these the stock 110" heads reworked? What do you think of this new design? Seems like they might be easier to set up than the htcc. Just a basic cleanup, zero the deck height, screw it together and go.
thanks,
Philip

[Mike]

Yes, they are ported stock heads. We've got special (exclusive) pistons to restore compression losses due to the port/valve/cam work for the 110 motor. This way we retain the ACR's and 110 script. The new design is not great in stock form but responds to porting very well.
Mike

[clun]

Mike - 2007-09-19 6:53 PM

Yes, they are ported stock heads. We've got special (exclusive) pistons to restore compression losses due to the port/valve/cam work for the 110 motor. This way we retain the ACR's and 110 script. The new design is not great in stock form but responds to porting very well.
Mike
Mike,
Could you enlighten us on what modification is being done to the 110" stock heads, and the ccp we would see and the compresion.These i assume would be fordged pistons am curious how much a person could mill off the heads for a bit more compression. i realize that stock cam has a very fast close on the intake so not a lot of room for a lot of compression but with a good pipe and and tune it should be close to 100 hp and 115 tq or so?? anyway thanks
Happpy

[Mike]

The stock heads do not allow for more than .030 decking until you get into the ACR relief. We used the H-D SE forged high comp pistons with the Baisley heads, but milled the dome of the piston to correct the compression to 9.7 when used with the 255 cams. This was done to correct for the chamber volume gains due to the valve shrouding changes and original cam TDC settups and for a slight increase over stock (9.3). Cranking pressure was approx. 220lbs (ave. both cyl.) with fairly fresh rings, so may go up with sealing. This is higher than I'm normally comfortable with but if you see Terry's reply in the dyno library you'll see it was not a problem with a good tune. Tuning will be critical to prevent detonation and even then some may creep in, so long as it does not cascade into constant severe detonation, this will be acceptable.

The porting was Baisley's Prostreet port work. Fully ported with just slightly larger intakes, stock exhaust diameter (I think, would want to verify). The 255 cams obviously hurt top end power but still made better than expected which helped pull the tq curve out into the higher rpms, with the ported heads. We are looking into having some test cams made to captalize the tq curve as we are getting more and more requests for low to mid range tq improvements in stock 110 setups and others. So far no one has cams that are even remotely close to the 255's and we feel there has to be room for improvement while not sacrificing the 1500-3000 area. It will still be a choice of low end tq vs high end hp when planning motor packages. The pipe was less of an issue with the 255's but still important, as expected.
Mike

[clun]

Mike - 2007-09-22 8:29 AM

The stock heads do not allow for more than .030 decking until you get into the ACR relief. We used the H-D SE forged high comp pistons with the Baisley heads, but milled the dome of the piston to correct the compression to 9.7 when used with the 255 cams. This was done to correct for the chamber volume gains due to the valve shrouding changes and original cam TDC settups and for a slight increase over stock (9.3). Cranking pressure was approx. 220lbs (ave. both cyl.) with fairly fresh rings, so may go up with sealing. This is higher than I'm normally comfortable with but if you see Terry's reply in the dyno library you'll see it was not a problem with a good tune. Tuning will be critical to prevent detonation and even then some may creep in, so long as it does not cascade into constant severe detonation, this will be acceptable.

The porting was Baisley's Prostreet port work. Fully ported with just slightly larger intakes, stock exhaust diameter (I think, would want to verify). The 255 cams obviously hurt top end power but still made better than expected which helped pull the tq curve out into the higher rpms, with the ported heads. We are looking into having some test cams made to captalize the tq curve as we are getting more and more requests for low to mid range tq improvements in stock 110 setups and others. So far no one has cams that are even remotely close to the 255's and we feel there has to be room for improvement while not sacrificing the 1500-3000 area. It will still be a choice of low end tq vs high end hp when planning motor packages. The pipe was less of an issue with the 255's but still important, as expected.
Mike
Mike, thanks for the detailed explanation. I am a bit confused on the pistons. one instances its the SE pistons then its the J&E piston. i guess i am not getting it is all.. i would like to do perhaps the heads. and set of pistons since the stockers i understand won't work? thinking of trying to run a HQ 575 cam with the headwork.intake is 20/40 240 duration .575"lift .161" TDC LIFT .
exhaust is 52/24 256 duration .530"lift .188" TDC LIFT
this cam shines with the 10.5 compression.. not sure what it would take to get the everything to work but i a sure its gonna require what your taking about above.. just may even be a good set up for the 251 camset but then we give up the low end again.. its too bad we can only take off .30 before your into the ACR's. not able to figure it all out myself but i like the idea of the stock heads being used. once again thanks for the info. its interesting for sure. Happy

[skyhook]

I'd also be concerned if we shaved the heads .030" and used a thinner head gasket, would the acr hit the piston?

[Mike]

Sorry for the confusion. When we port the heads we almost always gain some chamber volume which lowers compression when used with the stock flatops. Since we cannot deck the heads to gain back that compression (even to get back to stock comp) we've used the SE pistons and then milled the pop-up portion down until we get the total volume we are targeting. If we are going to use cams that can stand more than stock compression or more than even the SE's will give, with the increased chamber volume, we use the special JE's we've had made. We also adjust the compression in the same way with the JE's, but with a higher dome then the SE's, we can adjust to higher final ratio's (typ 10-12:1 depending on cam TDC's and other factors). As such, we do not deck the heads any more than required to restore the gasket surface to true flat. In your proposal, when used with Baisley ported heads, the SE pistons would not give you 10.5 compression (10.0 tops even unmodified), so the JE's then corrected for 10.5 would be used.
Mike