Porting and polishing the heads?

[MDavis0424]

How much did you lose on the bottom end, did it affect day-to-day drivability?

Do you still have the heads, where you could post pics others could use as a template?

 

[NateRW21]

That may be the gains while N/A but when blown you would see much higher gains. That is where ported heads really come into their own and start paying for themselves.

Actually... haven't had it dyno'ed yet... and now that I think about it, 60HP might be a little bit reserved; the difference between the PI and non-PI is 40 alone, not factoring in the CNC job, cams, slightly higher compression or tune. So I suppose maybe more like 70-75HP.

Anyway, it's not that I was dissapointed; I wanted to keep it N/A... and on these engines, changing to worked PI heads and new cams is undoubtedly the best bang for your buck without jumping into the power adders.

I was just saying that given the displacement difference and technology difference between the two (the 3.9 having already been built to make better use of it's abilities), 29RWHP is a pretty significant gain without even being able to tune it.

 

[cammerfe]

Head Work

As some of you know, I'm in process of re-working a complete Jag 4 litre engine to go into my '02 LS land speed racer/daily driver. I just got the block back from the machine shop and am now waiting for pistons. Here are some preliminary answers:

I have a friend who owns 'HeadWinds', an engine shop that specializes in head work. I'll have a five angle Serdi job done, along with new titanium valves and hardware. Titanium valves require beryllium copper seats and guides. We'll then blend and scuff to remove boogers and dingleberries. I don't plan on removing much material or altering runner shapes significantly.

I've arranged to have my cams reground by Competition Cams. I'll post more information when the cams are back to me.

I'll be running both a pair of turbos and keeping my 300 HP NX Pro spray system.

More later--
KenS from Ben's Place

 

[titleisttony]

chew on this

I for one believe that there are all sorts of power gains from conventional "racing" mods. That being said, you would have to do a lot of modifcations to make any of them "worthwhile". Think of it this way, your engine is like an hour glass. Increasing flow is going to help the most when you maximize flow throughout the whole engine, intake, combustion chamber, and exhaust. So just porting and polishing the heads will help, but not as much as it would if you also opened up the intake, and the ENTIRE exhaust(including the whole exhaust system) from the exhaust side of the heads to the "headers" on back through a true high flow exhaust system. I wish that I had enough time and money to open up the entire engine. I think we would all be in awe of the total gains. Hopefully I will get to do it in the next couple of years. Has anyone thought of sending their intake and heads to extrude hone? When (if) I get to do a complete performance overhaul, that is where I am going to go. I just wanted to put some food for though out there in case one of you guys out there with loads of dough wanted to really do up their engine so we can see how much this car is capable of.