My 1st completed set of ported heads.

See pictures here: (click on the "iron L98 heads finished porting")
http://f2.pg.photos.yahoo.com/gtaracer1

See this thread for my previous flow numbers and comments
https://www.thirdgen.org/techbb2/sho...hreadid=198595
Also listed here w/ stock numbers 1st, 3rd numbers ported w/ Stainless Steel valves

Side by side comparison
Intake
Lift_______CFM
0.097...52......49....54
0.194...101....100...108
0.291...145....146...158
0.388...167....183...189
0.485...179....200...206
0.582...185....200...203

Exhaust
Lift_______CFM
0.075....35.....35...30
0.150....62.....61...63
0.225....87.....91...102
0.300....105...125...137
0.375....106...138...144
0.450....106...139...144

Final numbers here: 2.02-1.60 w/ Manley valves

Lift......Intake....Exhaust
.100....56.43.....48.22
.200....113.36...105.54
.300....163.94...146.51
.400....191.16...166.22
.500....197.16...170.49
.600....202.70...171.34

Intake really did not get any gains. Worse actually. Obviously something did not help me. I really opened up around the valve guides. Bigger valves, too...meaning slower velocity I think. Still better than original stock numbers, though.
Exhaust I made a big jump in improvement. Did something right.

Does my exhaust flow too well compared to my intake flow? Any comments on my intake results? All comments welcome.

Porting my headers to match, also. I'll get a picture up of those soon.

Hopefully be on the car and at the track by the 16th for some real world results.

Edit: After looking at the heads, seems the valve job "created" a ridge that needs blending back in. Hesitant to blend that in though, don't won't to mess up the valve job. Not sure if that is where my "lost" flow is either.

 

My experience with low-buck home porting lines up pretty much with your flow bench results, although I have never flowed any of my own heads. My general experience is that it's pretty easy (and beneficial) to port out the exhaust. Intake is not so easy to do well. Stuff that looks like it should give impressive gains on the intake really doesn't. Stuff on the exhaust that looks like it should give impressive gains does, however. I have no explanation for this that I have ever been totally comfortable with.

Basically, it always seemed easier to me to get the exhaust flowing well than the intake. Looks like that's what you're running into.

I never did bigger valves in a stock head (expecting no real improvement, so I never tried) but I did do a lot of work with the valve seats and the back of the valves themselves. Multi-angle valve jobs and backcutting the valves themselves, going from diagrams and pictures I've collected over the years. Seemed to help a little, too.

My experience is mostly anecdotal. Try this, try that, car runs better or worse, etc.

All your numbers look a little low. Stock and final ported numbers. Flow bench numbers vary. I wouldn't be so quick to call it a failure. Put them on the engine and see what they do. ANY flow improvement is good if you match the rest of the combination to take advantage of it.

Your old I/E exhaust ratio was a dismal 60%. Your new ratio is a stunning 86%. (I'm not looking at anything over .500" lift since you probably won't be lifting the valves much higher than that in reality). A single pattern cam would probably work well with those heads.

Also, your larger 2.02 intake valve out-flowed the smaller one (1.94?) by a handfull of CFM until you get up around .500" lift. Below that it still gained. That's all to the good. Peak numbers don't determine power. Average numbers do. You still gained, even if only fractionally.

 

BTW- thank you for posting the good, the bad and the ugly. Seeing reality is appreciated. Anyone who's been into performance for a while knows that the road to fast isn't a straight line with every chage being an improvement.

 

Did you unshroud the valves at the chamber walls? It didn't look like it in the pic's and you REAALLLY need to do it when putting in bigger valves. did you actually get teh ports cut for the bigger valves or just use a grinder? I used a cutter when I did mine and it removed huge amounts of material even after substantial porting for the before and after tests.

Edit:
Damon posted while i was writing mine, he said
"Your old I/E exhaust ratio was a dismal 60%. Your new ratio is a stunning 86%. (I'm not looking at anything over .500" lift since you probably won't be lifting the valves much higher than that in reality). A single pattern cam would probably work well with those heads. "
Which is an excellent statement.
He also said
" Intake is not so easy to do well. Stuff that looks like it should give impressive gains on the intake really doesn't. Stuff on the exhaust that looks like it should give impressive gains does, however.
Which is also accurate. The intake is almost an art form compared to the exhaust, lotsa trial and error.
BTW when reading the rest, I was porting heads professionaly when I did mine, and had full access to a superflow bench to test and do a little at a time.
End Edit:

It may just be the pictures, but what i notice is that
1. the valve job doesn't look that good
2. You've got huge amounts of area to unshroud the valves, in the chamber, you really need to do it or the bigger valves can actually hurt flow. in picture_0320 where i'm talking about is draw a line verticaly through the intake valve about 2/3's of the way across, closer to the center of the chamber. Everywhere to the left of that grind out and angle towards the outside of the chamber to give the air flowing out of the valves a smoother curve to flow across. I'd take the far left side almost all the way out to the gasket line, like maybe 1/16-1/8 inside of it. Use a sharpie and a head gasket, draw around the inside of the gasket and grind till you hit the inside of the sharpie mark, making a nice smooth curve out. grind down the lip at the bottome edge of the chamber by the valves. I usually take the valve out, flip it upside down, move it down about 1/8 and use a sharpie again to mark out a nice smooth curve, this time grinding to the outside edge of the sharpie mark. Do the outside edge around the xhaust valve as well. Also around the spark plug hole, grind out that ridge.
3. the bowl work looks decent, but could use a little refinishing to lose some of the irregularities and bumps. I don't mean the rough finish, but the high spots.
4. The throat looks a little narrow. A good rule of thumb is to open it up to between 80 and 90 % of the valve size, but NO LARGER or once again you'll lose flow. I like to go closer to 90, some like to go close to 80.
5. It's hard to see the short side radius from your photos, especially the intake. The exhaust looks pretty good from what i can see of it, but its also the easier to get to of the two. Make sure that that's a nice smooth radius. I like to get a playing card, measure the height and depth from the valve edge, mark it out on the card, and cut a quarter circle betwen them. Then use that as a template to get the middle of the radius close then smooth out the rest using that as a guide.
6. You could do a little more work at the back of the valve guide, but it's close, it's not what's hurting you, be worth a couple cfm at most.
7. You really could open up the intake ports around the pushrod pinch quite a bit more, though measure constantly to make sure you don't cut through. You loose flow when you get an expansion like what happens right on the other side of the pinch. What could be happening is that the rest of the port is close, but that restriction isn't letting those improvements reap their maximum benifits.
8. I really wish i knew where the pictures of mine were, and since i sold the heads i can't take more, snarl, grumble, complain. Otherwise I post a few to show the diffences more clearly.
9. also did you or whoever flowed the heads correct for standard temp and pressure? Can make a big difference in the flow numbers.
10. I had to put new exhaust seats in mine after cutting for the bigger valves, you didn't have too? The reason i had to was that to fit the 1.6's right I removed most or all of the hardened area, so I had to put new ones in to keep the head from eating itself.

Hope this all helps, dunno if you've seen my other posts on porting these heads, check out the link in my sig, I'll be happy to help as I can.

 

I do not have pictures after valve job, or resurfacing, etc. I can do some if needed this weekend.

No. I did not. Machine shop said I probably lost some flow there due to restriction. I took some advice from a post on another board that the compression increase would be better than unshrouding these heads.



Machine shop used a cutter. PIctures show a cut for bigger valves.

1) pictures do not show valve job
2) I reckon I need to unshroud the valves...looks like more work for me. Oh Joy!
3) Easier said than done.
4) It just seemed like I would of had to port into the "seats" to do that. I think it is more than 80%, though.
5) Yep, intake harder to get to. I worked on it some after my dad said it needed more work. GUess not enough. SHop said that was an area I could get better.
6) OK
7) Really. That is an easy area to get to. Couldn't hurt could it to open it up? I'll see what I can do there.
8) Agreed
9) Yes. Got a complete paper full of numbers including correction factors, etc. They flow the heads at 10". I multiply those numbers by 1.67 to get 28" for comparison purposes and conversation.
10) Don't know.

I have read lots of stuff, including your posts. Makes more sense once I do some actual porting though. Live & Learn.

 

I'm willing to do some unshrouding if it will help that much. I am real hesitant to go into the bowl or pockets though. Don't want to do another valve job.
I'll do some blending I think, and the unshrouding. WIll just have to be cautious.

 

Heh, that's why the valve job doesn't look good, chuckle. For the rest it is hard to see the stuff on the pics too, I wouldn't worry about the bowl work too much, like i said it looks decent already. You will lose some CR by unshrouding the valve, but only a couple of cc's, not a huge amount, easily made up for by running a thinner head gasket, and the increased flow will bump your effective compression, so not as big a deal anyway. as far as the throat, like i said, it's hard to tell from photo's on the net.
Be careful around the pushrod pinch once again, there's a lot of material there, but if you go to far your screwed. If you're careful and blend it in well you can get 4-5% more on these heads in my experience. I also gasket matched mine to a 1205 intake gasket, but that don't make a hell of a lot of difference, though if you're using a good intake, at least get it close to the intake port size.

 

Do you know of any kind of measurements I can use as a guide for the pushrod pinch area? Such as a typical width in the middle, floor, and roof? I'm limited in Tools to measure the thickness of metal. IIRC I have about .9" width in the pinch area in the middle.

I'll take my heads off my car and use those gaskets to begin my unshrouding. Will an old valve be all I need to protect the valve job?

Also, I have Manley Raceflo valves. Shop didn't mention anything about back cutting them. Are they good to go as-is, or do they need some additional work?

Appreciate the help fellas.

 

Agreed on unshrouding the intake valves near the chamber walls. I'll take flow over a modest bump in compression any day of the week.

 

How are you flow benching these heads??? I have seen guys with a vacuum cleaner hose with a vacuum gauge on it. They then just stick it to the hole and not vacum reading as the vacuum suck air through the port???

 

Forget that valvejob cut on to your heads. Your seat area is too narrow to get a good transition from your throat area to the seat.

Yes definately lay back the chamber walls around the intake valve to unshroud.
You also need to widen the sides of the throat area just under your seat cut.

Your intake numbers seem to stall near .500 lift. There's a couple of things that can cause that. The most common is a bad transition on your short-side approach to the intake valve.
You need to check that out carefully. Some people lower the floor too much right at the short-side turn. This will hurt high lift flow.
The other thing that can cause stalling like that is tubulence around the floor of the intake port. Many porters will widen the floor a little bit to slow the flow here & reduce the turbulence.


When you're done just take your heads back to the shop and have them touch up the seats real quick.

Ideally you want to get the machine shop to put a seat cut on there about twice as wide as the one you've got. That will give you a much easier time blending the edges of the seat cut for a smooth transition.

 

No you don't need to back cut the manley valves, they come like that already.
Yes, you can just use an old valve to protect your seats, that's what i do, though you'll want to pull the valve and blend the seat in afterwards, VERY CAREFULLY, unless you want to pay for another valve job.
Agreed with 305 on the widening the seat as well, theoretically narrow seats will flow more, but in practice the difference is very small, and the wider seats will be much more durable.
As for the pinch area I used a cheapo caliper to constantly measure. The trick is that the bottom of the port is thinner than the top. Couple of months ago car craft had a good article on porting and displayed a homemade tool to measure how much metal you had left. I took mine out to well over an inch (somewhere around 1.2) and squared it out, but at one point i did end up welding up at the bottom where i cut through on one port, after that i angled it in towards the bottom on the rest. As a guestimate i'd say you could go to 1 without concern, maybe even 1.1, but keep it narrower at the bottom. Your machine shop could probably sonic test the thickness for you pretty cheap, then you would know for sure how much you could take out. Just for reference superflow says you can get 3% of your flow here, the unshrouding can be 10% and the bowl work can be up to 25% (combined, lots of different area's in the bowl, with the shortside radius being most important). Since you've already done some work though, I'd say you could realistically see another 15-20 cfm with this work on the intake, probably 5 on the exhaust.

 

rhuarc31, When you say narrower at the bottom, you must mean the roof of the port (long turn) as looking down through the port throat?
As I mentioned above, a slightly wider floor will flow better at higher lifts, but cutting into the short side too much will really hurt you. The air likes a straight approach to the intake valve on the short side with a very smooth turn on the floor. The further away from the valve seat you make the turn the better. If you've lowered the short side approach you could build it back up with epoxy and shape it the way you want it for a higher approach.

When I was talking wider seats, I meant before blending the leading & trailing edges of the cut. Once they're blended the seat itself becomes narrow with a good transition on each side.

Some machinists take this to mean they should cut a narrow seat in the first place because narrow flows more. This doesn't work if you have no room to blend the transitions. Most people who get heads back with a narrow seat are afraid to touch them any more and just leave the sharp edges at each end of the seat cut.

If you use a fine 80 grit or more cartridge roll you shouldn't hurt the seat too much.
A machine shop SHOULDN'T charge you for a full valve job to just retouch up the one seat cut! It shouldn't cost that much.

 

Nice explanation on the valve seats 305, and of course you are right on the intake port, I was looking at picture 318, and of course in the picture it is the bottom, but it's actually the top of the port. So make the pushrod pinch a little narrower at the TOP of the port, or the BOTTOM of the picture, however you want to look at it. The reason is available metal thickness, really has nothing to do with airflow shape or anything. Hope i didn't screw ya up smithtc.

That also sounds like a good description of the shortside radius. Like i said, i like to take the highest point(when the head is upside down, once again, would be lowest if head was rightside up) in the center of the port roof and form it into basically a quarter circle to the throat in the middle and blend outwards from there. Ends up looking a 90* bend in a mandrel bent pipe.

 

Got some more pictures up at the website in 1st post under new album name (heads, headers, and engine)...

That's a lot of information to digest, thanks...I'll try and get 10-20 more cfm out of the intake side and I will be satisfied.

Fixin to measure the depth of piston in the cylinders, get some new gaskets, and then see about doing some more work on these heads.

Testing inserting a picture below of a piston...detonation?

 

More Flow Results:

After opening the pushrod pinch to 1.0" generally (from .8-.1-.9), and after letting my dad do some combustion chamber unshrouding. No pictures yet...but one thing left to do is remove the ridge that was left from new valve job. It needs to be reblended back into the bowl. Don't know why I didn't notice it before...very apparent. Anyway... here they are to date.


...........Previous................New
Lift......Intake....Exhaust...Intake....Exhaust
.100....56.43.....48.22.......59.45.....44.15
.200....113.36...105.54.....123.51...97.85
.300....163.94...146.51.....171.23...138.81
.400....191.16...166.22.....205.63...164.90
.500....197.16...170.49.....206.73...169.00
.600....202.70...171.34.....203.41...168.14

Don't know why the exhuast went down. Any ideas?
They said it was the same cylinder...who knows?

I'm going to remove the ridge some, blend back in...and put these heads on. Don't plan on flow testing them again for now.

 

The variance in your exhaust flow is pretty low, could just be different barometric pressure, temp, etc that day.

 

pipe/no pipe?

 

From the numbers it looks like the intake port was flowed without using a radius inlet (puddy). Makes a big difference.

 

The sheet they provide shows all these calcs where they sre supposed to account for that. 8 cfm difference??

From my talks with them in the past they use pipe and radius.
Maybe their machine just ain't no good. Good enough to check improvements ,though...right?

These are the some guys that said my 400 block's crack wasn't fixable, or worth fixing...and RB said the opposite basically.

I will be checking into using other machine shops in future.

 

You hit the nail on the head right there.

Before and after is what to look for. As long as there's an improvement, then your effort was worth it.

 

Some thing just doesn;t make sense though.
I get much higher numbers. Have so on numberous different sets of like heads. Have guided other friends on doing theirs and theirs check out better too. Same or close to my results. None of us are "experts" at this. Do pretty much the same thing as you are doing.

My other friend who doesn't like to spend (waste) time porting stock heads gets better numbers than you've gotten, by just installin a 2.02 valve with a multi angle valve job and a bowl hog.

Something is wrong with their equipment or method I think.

 

Say F-Bird...

Any flow numbers from your ported Vortecs...or any times from your 406 Vortec powered car, yet?