blown 944

Vic, I didn't see your question about the spring cup. I should have posted a pic of the result. I did a couple of test pieces and ended up taking that lip off except at the base on a couple pieces. Once I figured out how to true the cup in the lathe easily I was able to get a good result. I then tried to bend the inner lip and it held up good.

I did however start to think about it and I am thinking that using the parts with the bump may be the safer route to go as there is nothing that could break off and the bump should be enough to keep the spring aligned. There isn't really much lateral load, so it should stay put.

I did a little further research and have found a replacement outer spring with a much higher spring rate that should work as a drop in. So I may just scrap the whole inner idea. I just ordered a set of both and will do a test fitting next week. I'll post the results. Fortunately each set was only 50-60 dollars.

Pauerman

You are quite a resource Sid - please let us know what spring combo works out cause I'd be all over getting something that works with the factory cup / retainer.

Thx

blown 944

Just a small update. I found that the inner valve springs I was initially looking to use did not offer much added seat pressure. I searched a bit more and found a set that bumps the seat pressure from a stock measured 115#'s to 140#'s and open from 240 to close to 300. These springs allow for a .520 lift cam as well with a little room for coild bind. Once I have everything running I'll post the part numbers for them. They do not require any machining to either the spring cup or retainer, whinch is also nice.

Other news is that I got some flow numbers over the phone today after dropping my head off to have it tested on a a superflow 600 this weekend.

I guess I did ok ,as the intake numbers came in at 230-234 @ .500 lift with a minimum amount of variance between cylinders. The .400 lift numbers also sounded good from his perspective. He also said that the flow was very steady and not too turbulent from his experience.

The exhausts flowed 196ish respectively with very minimal variance. I did a littel work to them around teh guide and at teh exit of teh runner, aalong wiht blending the liner to the seat.
I'm pretty happy to hear these numbers bc I did this using vision, feel, a set of reverse calipers and a digital caliper.

The guy that did the testing for me is known for being conservative as well. It didn't matter to me if the numbers were high or not. Just as long as there was a decent improvement over the stock 180 figure.

He thinks there may be a little more to be gained in a few areas, but was surprised at how consistent they were.

I'll post the full sheet after I pick the head up tomorrow.

refresh951

Very nice numbers indeed!

blown 944

Picked up the head and flow sheets tonight. Talked to him for a few minutes about what we could do. After speaking with him and looking at some other heads and the accompaniing flow sheets I have decided to have him redo the valve job on the intake seats at minimum. My current valve job was OK, but not designed around maximizing high flow (at least not the position of the 45 angle) . He thinks we may be able to pick up around 10 cfm over .400 lift. We also talked about going to larger valves yet (these are 47mm), this will require new seats yet again, but would allow for a better radius on the seat. With 49mm valves he thinks we may be able to achieve over 250 cfm @ .500 lift. We are also talking about using nascar take out titanium valves that he has along with the appropriate hardware. They have very thin stems and are extremely light. I just don't think I'm ready to take the plunge on that idea yet.


Current specs:
951 turbo head with extensive porting by me.
47mm valves using 30/45/60 seat angles. Valves have 44.5 and a back cut 25degree angle.

@.100 63.5 cfm
@.200 129.1
@300 174.1
@400 210.7
@500 231.4

Average 161.76

for comparison, a "large valve" top flowing head has an average of 171cfm (looking at the flow data)

If he is correct, I should be able to get an average flow of 170 cfm with the larger valves or 165.5 with the current valves.

Exhaust with portwork around seat, guide and at exit:

@500 192cfm

All tested on a superflow 600 at 28" water column.

What does all this mean? Well compared to my stock valve head that was on my last engine flowing 200@.500....I've made significant gains this go around. So it should make more power at lower boost.

Going to the larger bore has afforded me the option to go to a much larger valve size, while still being able to minimize shrouding.

Redoing the valve job, or doing the larger valves, will add a couple of weeks to being able to bolt the head down, but I think it's more than worth it. Although ....I'm undecided on going larger valves or not.

URG8RB8

Great detailed information Sid! Looks like you have a winner either direction you head.

1987Porsche944WithRealLongName

So now you're about where the typical 16 valve turbo import is from the factory
Not bad

did you not get the exhaust port flowed just to see?

blown 944

I did, I noted it above. With the work I did to the runner and seat area I gained a bit of flow on them too.


Also, thanks Eric

333pg333

Good stuff Sid. Not sure if flow benches are a little like Dynos in that they can give different numbers but where you’re aiming seems pretty similar, if not a little better than the numbers I got. I wonder where you’ll see the greatest benefit…earlier spool, wider tq band, higher rpms? Either way, seems like a worthy delay.

What 16v turbo from factory??

blown 944

I know everyone loves pics and I'm sure Ill be posting a few more in the coming week. However, I just picked up my head from the final stage of flow work and the results are awesome.

This head is well beyond my expectations and the head guy was right about doing a competition valve job.

We picked up over 10 cfm at high lift consistently. I also equalized all ports to within 3 cfm at .500 lift (ranging from 249-251 cfm). I'm also very encouraged that they flow very well above .400 lift.

in contrast to my last head flowing 208 at .500, this head blows it away.

Shawn put together a graph showing my head against a lightly ported stock valve head.

This was flowed on a superflow 600 bench by an unbiased third party.



From what I've seen, I'm on par with the best heads that have even larger valves.

I have another head in mind that will improve by a great margin.

blown 944

I will also add a bit of technical info regarding the valve job.

The valves are cut with 3 angles

the 45 degree is from outside and about 1/16 wide seating very close to the edge
the next angle is a 30 degree that is about 1/16 wide
the next is a 25 degree angle about 1/16 wide



the seat angles are (starting from throat into combustion chamber)

70 degree angle from about 1/8" of seat edge with about 1/8" width
60 degree angle about 1/16" wide
45 degree angle less than 1/16 "
30 degree angle less than 1/16" out to chamber

I also got a second opinion on the inner valve springs (small block chevy 1.010 ID.

They are good to right at .500 lift but will coil bind at any more lift.

The seat pressure when combined with the 951 outers is 145#'s
the open pressure at .500 lift is 290#'s

I may try to take a little material off the inner stp of the retainer in order to go to a .525 lift cam.

refresh951

This 8V head is nothing short of remarkable! Outstanding results! Your ability to get results have been demonstrated over and over and I am taking notes.

URG8RB8

Nice job Sid, very good numbers indeed! So what is the difference in "competition" valve job and a true 5 angle valve job?

V2Rocket

hows the exhaust side?

blown 944

Eric, mine is a 7 angle valve job total.

A 5 angle is generally close to the way mine was done but without any back cuts to the valve. They also don't generally use a flow bench to position the seat angles for optimal flow.