Lambo-Bully

I've got all the stuff to port &amp; polish, and have already done the intake manifold and exhaust manifold. Since the head is completely gutted, I was going to p&amp;p it, too, but friends recommend extrude honing. I've seen the results, and they're very impressive, but also very co$tly! It'll cost $1300-1350 for the total package, both manifolds &amp; the head. Should I? HMmmmm, I've got the $, just wondering if it'd be worthwhile compared to doing it myself. Only differences would be a little higher polish, and completely through the whole passage, where I can only get about 1.5 inches into it(like the intake manifold). Any thoughts?<ul><li><a href="http://www.extrudehone.com">extrude hone website</a></li></ul>

squidix9

Only you can do the math.

The top teams will go to great length's for every stray HP they can squeeze out of their motors. But, for you, you have to draw a line somewhere.

When I look at my car and see what Audi did, and what it must have cost, I have to figure they were nut's. But, they had the money, and they felt it was worth it.

xr4tic

My experience is limited to two types of heads, the one on my Merkur XR4Ti and the one on my Audi, so I am by no means an expert.

My XR head was designed in the early 80's and took a LOT of work, mainly in the bowls, short side radius, and exhaust port. The ports go into the head, and make a 90 degree turn down into the valve area (8V head)

The A4 head, by contrast, needs very little work. The ports go straight into the valves. The main thing to do is open the intake and exhaust ports to the size of the gasket. The bowl looks good as is. The main benefit of porting the head and manifolds to the size of the gasket is to make sure the openings match, to make the transition as smooth as possible, and make them all the same size - "Blueprinting"

The 20V head looks to be flow limited by the cam and valves, so I'd put the money towards Schrick stuff first. Keep in mind some low-end power will be sacrificed with bigger cams, and even opening the intake ports up could result in a loss of low-end power (the larger volume causes a drop in air velocity when not in boost)

If the head is flow-limited by the cam, then you might only see benefits in the mid RPM range, no change in the Upper RPMs, and a loss down low.

At most, I would think that the Extrude-honing wouldn't be worth more than 10hp at the most, that makes it a very expensive 10hp.

s54m3

are you willing to spend that cash? If you drag race or scca your car and do not mind spending the $$$$; then do it. But for the street i would not do it. My exhaust manifold is ported and polishied. Can you also get a flow bench to measure? let me know...

squidix9

by going to a stroker crank you overcome the problem of opening the ports. A taller piston to give you some compression and draw will also help enormously.

Audi2ptzero

dropping compression a bit but the added air volume should help when porting the head. I had all of that done on my 2032cc motor using a AEB head that was ported for max flow, schrick cams on a ATW block.

xr4tic

A stock 1.8T has a rod/stroke ratio of 1.67
A 1.8T rod and 2.0 crank has a ratio of 1.55
My tall deck 2.0 rod and crank is 1.71

A lower rod/stroke ratio will have more intake velocity than a higher rod/stroke ratio, making it better for low-end power, but higher ratios have better upper-RPM breathing.

squidix9

piston's too.

I have formula 2 piston's giving me 14:1

Audi2ptzero

14:1 is way too high for a turbo car and a 14:1 in a NA is still lower then a turbo car running 1 bar of boost and 9.5:1.

Audiboy

14:1? wow. I only know diesel engines that start in that ratio.