Valve angle degree VS Piston crown

[highpsi93tsi]

Just wondering what the valve angles are for a 1G Cylinder head. (stock iron head gen2 SBC is 23 degrees, killer race cylinder heads can be as low as 14 degree...promoting a better flow characteristic)
It doesnt matter as those are V-stlye engines and these are straight..but it still matters.
Anybody know?

 

[pinknuggit]

44.5 degrees +/- 1 degree.

The valve angles in vortec chevy heads are not 25 degrees. They are 45, which is what about 80% of the heads on the road are. There is nothing lower than 30 degrees in any engine. The less of an angle on the valve face would Hurt the air flow. 15 degrees is practically flat and there is no way to grind the face of the valve. The angle of the base of the valve stem is about 25 degrees, and you can not cut any less than that or you are cutting into the valve itself. All of the valve grinders at work can only go to 29 degrees. In addition to the valves being less of an angle, the seats also have to be at less of an angle too. A 30 degree seat needs a 30 degree valve. No one makes any seats that are less than a 30 degree angle, even high performance ones.

You can see in my picture i drew up (keep in mind, i'm on a laptop mouse) the difference in a 45, 30, and what a 15 degree angle valve face would be. a 15 degree face is basically impossible, and it serves no purpouse. Also, diagram A shows what the airflow charachteristics are like with less of an angle, whereas diagram B shows that a greater angle increases flow.

The only valves which use a 30 degree angle that i build at work are a 248AMC (older jeep straight 6) Intake, Oldsmobile v8 exhaust, International intake valves, and 6.5/7.4 diesel intake valves.

People usually do a 30 degree angle on the top of the face, a 45 in the middle, and 80 degrees on the bottom of the valve as part of a "multi angle valve job".

 

[highpsi93tsi]

We're on different pages here. I wasnt reffering to the vavle face. A mid 60s-1986 Chevy smallblock has 23 degree heads. A 1968-1972 Mopar 340 has 18 degree heads and a NASCAR type full race deal can be 14 degrees. Just because these were 90 degree engines doesnt mean they have 45 degree heads. I believe you know what your talking about I think you're just reffering to something else. I know about 3 and 5 angle valve jobs but thats a different story as well.

 

[highpsi93tsi]

www.protopline.com/racingaluminumsbc.htm
Theres alink that'll show what Iam talking about. On this subject, does anybody know the cc'c of the intake and exhaust ports of a 1g VS 2g head??? That'll tell a tale.
And again, whats the valve angle???

 

[pinknuggit]

oh dOh!!! yeah i didn't even comprehend what you said. I was just reading what i wanted to read.

yeah i understand what you're talking about now. My little speech was about the angle of the valve face.

 

[highpsi93tsi]

Ant idea what the valve angle is in a 1g head? Or the intake and ex. port CC's?

 

[silverbulletAWD]

I'm pretty sure it's 10° from the HG surface. I checked one last winter on the CMM but I didn't write it down. I haven't cc'd any ports yet but it's really not that hard. If you try it let us know.

 

[highpsi93tsi]

They look pretty big...I'd say 170-190cc. Apparently a medium port job will flow 270cfm @ 28" water on a flow bench...same with the stock intake (cut in half..ported and welded back together) BJ said with a stage 5 port job and 330 lift or something they out flow chevy SB2 nascar heads(with over 700 cam lift!) with ease!!! (thats like 310-320 CFM...Insane! for a production based head) SB2 SBC heads are 10 grand a pair!
SOMEBODY CC 1G HEAD!! Theres so much power in these heads it isnt funny....remember when Sheperd ran 9s?? Then all of a sudden he was mid 8s?? Head.

 

[poorboyj]

remember when Sheperd ran 9s?? Then all of a sudden he was mid 8s?? Head.

Where is this information coming from. I heard differently.

Jay

 

[highpsi93tsi]

BJ let the cat outta the bag when HOTROD magazine featured Shep's car. Way more in-depth (engine wise) then any other feature ive seen on it in import mags. It was also the turbo but its mainly the head, intake and ex. manifold.

 

[silverbulletAWD]

If you can wait I'll have all of the info you could want later this fall. I plan to get pretty crazy with another head this winter. As far as cc'ing goes, it's really not hard you could do it your self easily.

I'm sure Sheperd has some seriously tuned and matched top end hardware. Ask anyone who knows anything about engine building and they will all tell you the power is made in the heads. And of course the intake and exhaust manifolds are another HUGE player in this game. I can’t help but be amused how so many turbo guys fail to realize this. It seems most people think the air pressure above ambient begs for larger ports and easily forgives any porting flaws. I for one will be starting with a 2g head for my next creation. It's much closer to the proper size intake port and instead of adding lots of metal only some needs to be removed. The exh. ports need the same care on either head.

highpsi93tsi- I will try to get a chance to bring a head back to my shop and re-measure the valve stem angle for you. I thought I remembered but I'm not positive. And I really don’t want to give any mis-leading info.

BTW- I would really be interested in seeing that article from Hot Rod on Sheperds car. Anyone able to scan it and send it to me?

 

[highpsi93tsi]

Bullet-your one of few that knows. The article was in the HOTROD mag that had an STi and a 03 Cobra on the cover saying "USA VS JAPAN" both have forced induction, both cost 30some thousand and both run high 12s..the STi went on to win. Sheps car was in the same issue and BJ had about 15 quotes in it on how they're running 160MPH on a .20 over 2.0L.
Best article ive seen in hotrod in a long time. he even told how they d-shape the ex. ports for more flow and velocity...also the ex. manifold and into the turbo. Hotter and more intense gasses=sicker spool. It works, but you need a flow bench, a die grinder and alot of epoxy to build the flat bottom ports. Upside down D. Insta spool.

 

[91TalonTSi_53]

They look pretty big...I'd say 170-190cc. Apparently a medium port job will flow 270cfm @ 28" water on a flow bench...same with the stock intake (cut in half..ported and welded back together) BJ said with a stage 5 port job and 330 lift or something they out flow chevy SB2 nascar heads(with over 700 cam lift!) with ease!!! (thats like 310-320 CFM...Insane! for a production based head) SB2 SBC heads are 10 grand a pair!
SOMEBODY CC 1G HEAD!! Theres so much power in these heads it isnt funny....remember when Sheperd ran 9s?? Then all of a sudden he was mid 8s?? Head.

One of my teachers said the best flow characteristics hes seen has come out of a DSM Head..I am at WyoTech

 

[highpsi93tsi]

Once engine builers REALLY get into the heads on these cars I think your going to start seeing lots more 8-second and some 7-second AWD DSM's. I also predict that Turbo,4cyl,AWD,streetlegal drag racing will be pretty big in the near future.
DSMS-VS-WRX-VS-EVO.
Its already HUGE in Australia but the record is held by Sheperd here in the states.
Ima get started now!

 

[LHP]

Just wondering what the valve angles are for a 1G Cylinder head. (stock iron head gen2 SBC is 23 degrees, killer race cylinder heads can be as low as 14 degree...promoting a better flow characteristic)
It doesnt matter as those are V-stlye engines and these are straight..but it still matters.
Anybody know?

The valve angles are aprox 28' per side int and exh for the 4g63, the more effective the engine the shallower the angle, some motorcycles are down to sub 20 degree included valve angles. LHP

 

[SpoolinGSX]

I cc'd a 1g head. The head has casting slag removed and a light polish but no porting. The head was also surfaced. Here are the results if it will help anyone:
Intake port
233cc
Exhaust port
82cc
Combustions Chamber
45cc

 

[FireyIce01]

Bullet-your one of few that knows. The article was in the HOTROD mag that had an STi and a 03 Cobra on the cover saying "USA VS JAPAN" both have forced induction, both cost 30some thousand and both run high 12s..the STi went on to win. Sheps car was in the same issue and BJ had about 15 quotes in it on how they're running 160MPH on a .20 over 2.0L.
Best article ive seen in hotrod in a long time. he even told how they d-shape the ex. ports for more flow and velocity...also the ex. manifold and into the turbo. Hotter and more intense gasses=sicker spool. It works, but you need a flow bench, a die grinder and alot of epoxy to build the flat bottom ports. Upside down D. Insta spool.

I have that issue... if I can find it in my massive pile of magazines (I get hot rod, car craft, import tuner, chevy high performance, and a few misc others) I'll try and get it scanned for you.

 

[silverbulletAWD]

FireyIce01 - Thanks!

SpoolinGSX - The stock comb. chamb. is 47cc by the book. I'm sure the resurfacing took a bit out.

That's an interesting contrast in those port sizes. Just another point to prove my 2g head superiority logic.

Andy