I was talking with my friends dad about Port & Polishing and head flow.He has a 2001 Ford lighting and hes building a motor right now.He knows more about engine than I do by far.I was asking him what he was going to have done to his heads when he sends them out.

Then I told him I planned on sending my P72 head out to a well known head shop in the future.Nothing crazy just a mild build 3 angle/port matched and CTR cams and maybe some ITR valvetrain and some tuning.He then said "Youll loose power if you dont get bigger valves".I said what?I dont have to upgrade to bigger valves, Im sure just the head work I said would give quite a bit of a gain.He said No youll actyally loose power becasue of the drop in compression.Well I could use a thinner 2 layer head gasket and bump it up a bit.

Then he tells me I cant use a Fuel pressure regulator on a stock fuel pump.Im not a Master mechanic or anything but is anything true what he said?Are our motors completely different and some of that might pertain to him and his build?

Thanks

 

your buddies dad probably isnt very informed about honda cylinder heads, or maybe any cylinder heads for that matter.

#1 you can definetely see gains with the stock size valves.
#2 there shouldnt be a loss of compression. you could even mill the head a little to bump the compression.
#3 you will be able to retain your stock fuel pump just fine, and running an adjustable fpr will be fine. you should also run another management system as well and tune it to get the most out of your modifications, dont just rely on the FPR.
#4 probably shy away from asking your buddies dad for advice in the future.

 

Your buddy's thinking is old Iron V8 thinking. It's from a time when cylinder heads were designed around pushrods and efficiency was compromised. The mating surface for most SBC and BBC is very poor and very inefficient from the factory. When cutting for a valve job typically they need to go bigger valves 1 because the **** was too small to begin with and 2 because a valve job would destroy the senstive seal that was made stock.

Most modern Japananese DOHC motors are so well put together that you are not in danger of hurting the seal (because of the harden seat) or the head by doing a valve job.

You will be fine with a fpr on a stock pump.

Have your friend take a look at what you are doing, maybe he could learn a think or two about how imports have been made for the last 10 years

 

Hes one of those "Im right, and your wrong no matter what" kinda guys about everything.

I wasnt actually asking advice from him just seeing what he was going to do with his motor and he pulled that.

 

taking material out of the combustion chamber will cause a loss of compression. The rest I think is b.s.

 

oversized valves in our motors will make the powerband shift up higher in the rpm range gutting your part throttle low-mid rpm driveability and narrows the powerband width.

oversizing in an all motor 1.6L -1.8L = peaky narrow powerband.

they're great for FI guys though...or if you you go for a 2L all motor where you can recover some low rpm tq.

 

He also said that his motor 5.4 ltr w/ SC compression is around 12:3.

Is that most lightings CR?

 

12:3? That'd be the equivalent of 4:1. I think something was misunderstood there. I'm sure it's right around 8.5:1.

 

I would have no clue as to what a typical racing SC'd Ford Lighting CR is. The stock SVT version is apparently much less than that when you google the topic (8.4:1 CR at 8 psi boost).

The neat thing about adding valve area though is that you can start playing around with flow efficiency (Flow Volume in CFM at various cam lift points based on Lift/Valve Area Ratio or Lift/Valve Diameter).

This is where the voodoo headporting stuff comes in that the racers will never share on a public forum.

The play here is to get the cross sectional area on the ports at certain points correctly so that the increased valve area with oversized valves doesn't slow flow speed down as much to affect the full trottle mid rpms and part throttle mid rpms.

They point out that perhaps the short side radius is one key point along the length of the port that you have to get right so that the flow speed arriving at that point isn't killed as much with oversized valves at lower engine speeds and low to mid cam lift.

 

Did he tell you to put the TORNADO into your intake to get better gas mileage. All kidding aside, dont ask questions to V8 guys( apples and oranges)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Michael Delaney &raquo;</TD></TR><TR><TD CLASS="quote">I would have no clue as to what a typical racing SC'd Ford Lighting CR is. The stock SVT version is apparently much less than that when you google the topic (8.4:1 CR at 8 psi boost).

The neat thing about adding valve area though is that you can start playing around with flow efficiency (Flow Volume in CFM at various cam lift points based on Lift/Valve Area Ratio or Lift/Valve Diameter).

This is where the voodoo headporting stuff comes in that the racers will never share on a public forum.

The play here is to get the cross sectional area on the ports at certain points correctly so that the increased valve area with oversized valves doesn't slow flow speed down as much to affect the full trottle mid rpms and part throttle mid rpms.

They point out that perhaps the short side radius is one key point along the length of the port that you have to get right so that the flow speed arriving at that point isn't killed as much with oversized valves at lower engine speeds and low to mid cam lift.

</TD></TR></TABLE>
Or with a little thing called V-TEC

 

even with VTEC though, if the SSR is too open or too steep, the flow speed dies too quickly and the motor stops making tq as you cross 8000 rpm and into the 9000-9800 rpm range. That's when you see the cfm's drop like a rock and the tq nosedives.

I remember John Judd saying that in his race motors, he tries to sustain hp after peak hp has been reached for as long as possible to maintain the momentum that he had built up.

VTEC (i.e. a larger cam lobe) isn't the only answer if the oversized valve kills your mixture motion from a lack of flow speed as engine speed reaches the upper range near it's redline.


Modified by Michael Delaney at 1:14 PM 12/26/2005