Ported Chevy 083 heads, the tpi project

[Orr89rocz]

Resized_20190306_180300_7978.jpegEh why not? They needed some welding anyway.

Whoa! Thats not what i meant by cutting runners apart to port lol most i have seen cut them long ways. Or are you building a superram lol

[Carnut1]

Resized_20190306_180300_7978.jpegEh why not? They needed some welding anyway.

Whoa! Thats not what i meant by cutting runners apart to port lol most i have seen cut them long ways. Or are you building a superram lol

The more I think about it the more I like completely siamesing the top of the runners to give the air a better radius to feed the tube from the plenum. It would also bring the resonance rpm up a bit. I think the super rams were about 6500 rpm. Thanks, Charlie

[tt 383]

Carnut1 your threads are always interesting, entertaining and motivating... Keep at

[Carnut1]

Carnut1 your threads are always interesting, entertaining and motivating... Keep at

I appreciate that, Thanks

[Carnut1]

Resized_20190306_211715_4333.jpeg

I was asked for a better pic of a runner with the bulges reduced. These need sonic work to prevent extra welding from breaking through. You can also see how the runner changes from round to D to round again.
This port is #1 so it has a heater hose notch on left and bolt boss bottom right.

[BOOT]

Resized_20190306_180300_7978.jpegEh why not? They needed some welding anyway.

If you keep the lower halves and make a new plenum, you pretty much have a superram.

[Carnut1]

Resized_20190306_180300_7978.jpegEh why not? They needed some welding anyway.

If you keep the lower halves and make a new plenum, you pretty much have a superram.

Boot, the pics you sent me got me thinking. Siamese the holes in plenum and top half of the runners. Not quite a super ram but not far off either. Thanks, Charlie

[NewbVetteGuy]

Resized_20190305_190617_4253.jpegResized_20190305_190734_1504.jpeg Some plenum work, open to slp runner size and radius. Added a few cfm.

QQ: Why the burr finish on both the throttle body entrance and the runner entrances? -Doesn't that make the entry "act smaller" because of the increased boundary layer? (I expected to see a smoother finish on the entries and burr on the exits to keep the entrance sizes acting as large as possible and then to effectively "simulate" more taper from the increased boundary layer as you transition to the rougher texture as you get closer to the intake valves.)


Adam

On something like this I like the rougher texture on areas that have slower airspeed. There are arguements on what the boundary layer is doing. I don't think anyone has textures totally figured out and where they help. I did an experiment not too long ago with a diamond style burr that cuts lines . Lines cut 90 degrees angle from flow actually picked up cfm. About the roughest texture you can imagine.PART_1544444396714_Resized_20181209_152207_831.jpeg

Thanks.
Feel like I'm back to knowing exactly NOTHING again (not that I was ever that far away from it).

Adam

[Carnut1]

QQ: Why the burr finish on both the throttle body entrance and the runner entrances? -Doesn't that make the entry "act smaller" because of the increased boundary layer? (I expected to see a smoother finish on the entries and burr on the exits to keep the entrance sizes acting as large as possible and then to effectively "simulate" more taper from the increased boundary layer as you transition to the rougher texture as you get closer to the intake valves.)


Adam

On something like this I like the rougher texture on areas that have slower airspeed. There are arguements on what the boundary layer is doing. I don't think anyone has textures totally figured out and where they help. I did an experiment not too long ago with a diamond style burr that cuts lines . Lines cut 90 degrees angle from flow actually picked up cfm. About the roughest texture you can imagine.PART_1544444396714_Resized_20181209_152207_831.jpeg

Thanks.
Feel like I'm back to knowing exactly NOTHING again (not that I was ever that far away from it).

Adam

Adam you did get me thinking. So I did some airspeed measurements of the lower half of the runner bolted to the manifold then used a much finer burr finish on the fast side. Bolted it back up and the cfm was the same. Thanks, Charlie

[dfarr67]

So what makes a GREAT TPI roller cam?

[cv67]

Those bases are a lot of work. Got a stocker to just over 240 cfm but the hours needed are rediculous...
Keep it coming!
If you got the time to hack on a good superram (aftermarket base) they can support a lot of power, plenty of 10-11sec cars still running them.
The SR is a good piece if you want lots of tq

[Carnut1]

Those bases are a lot of work. Got a stocker to just over 240 cfm but the hours needed are rediculous...
Keep it coming!
If you got the time to hack on a good superram (aftermarket base) they can support a lot of power, plenty of 10-11sec cars still running them.
The SR is a good piece if you want lots of tq

Vette, My question to you is were you flowing just the base or flowing through the head? I am figuring how much of a flow loss I can deal with from base and runners. Thanks, Charlie

[BadSS]

From the data I’ve seen it looks like 240-ish is about as much as you can get out of a ported stock base without any welding (flowed on the bench – not through the heads).

Regardless, to get any real benefit out of those SLP runners you have to gut the top of the runner and grind the divider down as far as you’re able to with a 6” shank burr. I couldn’t find any pictures of my own, but this one gives you an idea – this also shows the window most cut to be able to grind down past the halfway point (more along the lines of what Orr was referring to cutting the runners). This moves the powerband up a couple hundred RPM over the stock runners.


Just for some reference, I did a lot of porting to a stock base on my old IROC (9.8:1, 355, 218/228-110 flat tappet hydraulic) with an old set of the TFS G1 Twisted Wedge heads that probably flowed about what you got out of the 083s. It was traction limited with 26x11.5 ET Streets with 3.23 gears behind a TH350 with 3000 stall and ran 12.90s in near 90-degree temps. It ran the same ET whether I shifted it at 5700/5500 rpm or 5500/5300 rpm. Throttle response was insane (instant tire smoke in 1st) and would haze the 245/45/17s from a 50mph drop into 2nd gear. Super fun but hard to launch for sure.

I later swapped that intake for a box stock FIRST that others have mentioned and it ran 12.50s in near identical weather and track conditions. It rolled off just enough down low that recent and consistent launches were manageable, although you could still light the tires up at will in 1st. Shift points went to 5800/5600 but would run the same ETs shifting as high as 6000rpm.

I put a ton of hours, more than 20 I’m sure, in that stock base and SLP runners and that FIRST killed it. I do think the TPI/SLP combo is a good bang for the buck combo for those that have the knowhow and time to port them themselves. It’s also a good fit for someone that doesn’t race the car and just wants to have fun. However, the base to head and runner to base transitions are terrible and not indicative to good flow (or power), as you’ve already found out and proving.

That FIRST on the other hand was built with a clean slate (nothing is compatible with the stock TPI) and the transition points are much better, evident by the worst port flowing 301cfm and almost a .5-second reduction in ET over a pretty decent TPI/SLP combo.
Here’s a picture of one for the FIRST runners opened up to 1.92”. Stock are cast at 1.75” ID (on the right) and opening them up to 1.85” is a piece of cake.

[cv67]

Charlie I mostly had the bases flowed separately...best on a factory base was 244 but not on all cyls its just not possible as you know without welding
Accel base 272, Edleblrock 260s. 230s on a stock one takes some time but not so bad

I did bolt a heavlily ported Superram to a set of 195 st heads I cleaned up I have the dataaround somewhere but having recently moved it would be awhile before I could find it. The loss was so minimal I figured Id stop there.(BUT it took a LOT of work) With stock runners yeah they choked hard but the car still ran very well.

Fun seeing what you can do with old junk, sometimes what the bench says doenst mean it wont run well.
Hope your intake is a buddy favor youll go broke trying to charge for them lol.

Good work.

[Carnut1]

Funny and true, I have been flowing through the head so I feel good about that. I have pretty much decided since I cut the runners the top of the runners will have the divider removed and I will match the plenum. Yes, it is a ton of work and an interesting learning curve. So maybe the question should be for a hard running 355 with a 6500rpm redline how much flow do you need? Thanks, Charlie