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Gains porting afr195 on sbc 388

General engine tech -- Drag Racing to Circle Track

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68corvette
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Gains porting afr195 on sbc 388

Post by 68corvette » Sat Feb 08, 2020 1:49 pm

388cid engine, 10.7cr, rpm air cap, 243/251 110lsa .600".
HP peaked at 6100rpm 514hp.

How much HP do you think could be gained by fixing the heads velocity profile, shortside and seat profiles?
Or is the dual plane holding it back too much?

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Re: Gains porting afr195 on sbc 388

Post by Cris » Sat Feb 08, 2020 2:08 pm

Helpful to know if the AFR195's are the race ready version or the competition version. Also if the cam is a solid roller or hydraulic.

514HP is pretty respectable, but if you are looking more toward 550HP, you will need HP to peak around 6600RPM for a 388.

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Re: Gains porting afr195 on sbc 388

Post by 68corvette » Sat Feb 08, 2020 2:11 pm

Hydraulic cam, race ready version of heads.

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Re: Gains porting afr195 on sbc 388

Post by steve cowan » Sat Feb 08, 2020 3:04 pm

68corvette wrote:
Sat Feb 08, 2020 1:49 pm
388cid engine, 10.7cr, rpm air cap, 243/251 110lsa .600".
HP peaked at 6100rpm 514hp.

How much HP do you think could be gained by fixing the heads velocity profile, shortside and seat profiles?
Or is the dual plane holding it back too much?
I think your engine makes good power with the Airgap.
I think a Motown or 300-110 intake manifold would make a difference and either intake manifold need minimum work as they are nice castings.
Be nice to open the pushrod pinch to around 2.1" as I think 1.920" is to small for power above 6000rpm for your cubes.
steve c

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Re: Gains porting afr195 on sbc 388

Post by mt-engines » Sat Feb 08, 2020 3:13 pm

68corvette wrote:
Sat Feb 08, 2020 1:49 pm
388cid engine, 10.7cr, rpm air cap, 243/251 110lsa .600".
HP peaked at 6100rpm 514hp.

How much HP do you think could be gained by fixing the heads velocity profile, shortside and seat profiles?
Or is the dual plane holding it back too much?
i love fixing AFR heads. easy to pick up 70-100hp from what people seem to think are maxed out from the get go.

your combo sounds like it has a smallish carb. throw a 950 hp and a victor junior. slowing the heads down should net you very good gains.

ive done 385" with ported sportsman II heads 2.055 intake similar cam but with a hurricane intake and a 950 make 565hp. no reason you couldnt be there

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Re: Gains porting afr195 on sbc 388

Post by steve cowan » Sat Feb 08, 2020 3:30 pm

mt-engines wrote:
Sat Feb 08, 2020 3:13 pm
68corvette wrote:
Sat Feb 08, 2020 1:49 pm
388cid engine, 10.7cr, rpm air cap, 243/251 110lsa .600".
HP peaked at 6100rpm 514hp.

How much HP do you think could be gained by fixing the heads velocity profile, shortside and seat profiles?
Or is the dual plane holding it back too much?
i love fixing AFR heads. easy to pick up 70-100hp from what people seem to think are maxed out from the get go.

your combo sounds like it has a smallish carb. throw a 950 hp and a victor junior. slowing the heads down should net you very good gains.

ive done 385" with ported sportsman II heads 2.055 intake similar cam but with a hurricane intake and a 950 make 565hp. no reason you couldnt be there
I have never seen a set of afr heads up close, in your opinion what is the biggest dilemma, we have had discussions before on the forum and seems the wayward CSA through the Port is a issue, don't want to go bashing any brands etc I am always curious how people do intake ports differently to get to a common goal.
steve c

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Re: Gains porting afr195 on sbc 388

Post by 68corvette » Sat Feb 08, 2020 4:02 pm

mt-engines wrote:
Sat Feb 08, 2020 3:13 pm
68corvette wrote:
Sat Feb 08, 2020 1:49 pm
388cid engine, 10.7cr, rpm air cap, 243/251 110lsa .600".
HP peaked at 6100rpm 514hp.

How much HP do you think could be gained by fixing the heads velocity profile, shortside and seat profiles?
Or is the dual plane holding it back too much?
i love fixing AFR heads. easy to pick up 70-100hp from what people seem to think are maxed out from the get go.

your combo sounds like it has a smallish carb. throw a 950 hp and a victor junior. slowing the heads down should net you very good gains.

ive done 385" with ported sportsman II heads 2.055 intake similar cam but with a hurricane intake and a 950 make 565hp. no reason you couldnt be there
Engine has Q series 750 cfm quick fuel carb.
I personally like dart-2 heads. They are not a blow bench queens, but deliver well.

68corvette
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Re: Gains porting afr195 on sbc 388

Post by 68corvette » Sat Feb 08, 2020 4:09 pm

steve cowan wrote:
Sat Feb 08, 2020 3:30 pm
I have never seen a set of afr heads up close, in your opinion what is the biggest dilemma, we have had discussions before on the forum and seems the wayward CSA through the Port is a issue, don't want to go bashing any brands etc I am always curious how people do intake ports differently to get to a common goal.
There is no bashing if a head is designed for 500hp, then obviously its not a correct head for 550hp or needs to be modified.
You were not asking from me, but as I see it, the problem for this case is the small cross section area, head designed for lower valve lift (flow separation) and the velocity profile designed in port shapes.
Bigger heads from AFR would fix the biggest problems, but this time it was not an option.

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Re: Gains porting afr195 on sbc 388

Post by steve cowan » Sat Feb 08, 2020 6:29 pm

Thanks for your response,
Big Joe said numerous times he got 600 hp out of 195 heads and 383 combination but never disclosed if he rubbed on them.
With a average CSA of around 2.2" and approx 200cc that should make it peak around 6500 if everything else is in line.
Looking at afr website those 195 heads are at 308-233 cfm advertised,
I can see someone with experience working those heads to make the cross sections and speeds more in line but that would depend on how big the bowl area is because of the listed 2.08" Intake valve.
Again I have not seen those cylinder heads so I am speculating which is probably not the best option for me.
What are your thoughts on how you would approach those heads??
Another thing is some people buy those CNC type heads with no intention of rework.
steve c

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Re: Gains porting afr195 on sbc 388

Post by PRH » Sat Feb 08, 2020 6:54 pm

Any independent flow tests to see how realistic that 308cfm number is?

Are they pretty close to 195cc’s?

The 2019 catalog doesn’t seem to use the term “race ready” for 195 SBC heads any longer.
They are both “Eliminator” heads, but “Street” or “competition”.
The street 195’s have 2.050 intake valves and are shown to flow 280@.550.
Min csa of 1.905”

The competition 195’s have 2.080 intake valves and are shown to flow 304@.550 and 308@.600.
Min csa of 1.920”
Last edited by PRH on Sat Feb 08, 2020 7:08 pm, edited 2 times in total.
Somewhat handy with a die grinder.

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Re: Gains porting afr195 on sbc 388

Post by 77cruiser » Sat Feb 08, 2020 6:59 pm

Thought i read one of his posts that said he always touched them a bit.
Jim

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Re: Gains porting afr195 on sbc 388

Post by steve cowan » Sat Feb 08, 2020 7:35 pm

PRH wrote:
Sat Feb 08, 2020 6:54 pm
Any independent flow tests to see how realistic that 308cfm number is?

Are they pretty close to 195cc’s?

The 2019 catalog doesn’t seem to use the term “race ready” for 195 SBC heads any longer.
They are both “Eliminator” heads, but “Street” or “competition”.
The street 195’s have 2.050 intake valves and are shown to flow 280@.550.
Min csa of 1.905”

The competition 195’s have 2.080 intake valves and are shown to flow 304@.550 and 308@.600.
Min csa of 1.920”
I kinda assumed race ready and competition head meant the same lol
We both know most heads are not advertised port volume or cfm numbers accurate as well, most of the time :D
steve c

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Re: Gains porting afr195 on sbc 388

Post by steve cowan » Sat Feb 08, 2020 7:38 pm

77cruiser wrote:
Sat Feb 08, 2020 6:59 pm
Thought i read one of his posts that said he always touched them a bit.
Thanks Jim,
I wasn't sure, but nothing would surprise me with Big Joe, if anyone could do it with as cast heads Joe could. :D
steve c

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Re: Gains porting afr195 on sbc 388

Post by KnightEngines » Sat Feb 08, 2020 8:30 pm

mt-engines wrote:
Sat Feb 08, 2020 3:13 pm
68corvette wrote:
Sat Feb 08, 2020 1:49 pm
388cid engine, 10.7cr, rpm air cap, 243/251 110lsa .600".
HP peaked at 6100rpm 514hp.

How much HP do you think could be gained by fixing the heads velocity profile, shortside and seat profiles?
Or is the dual plane holding it back too much?
i love fixing AFR heads. easy to pick up 70-100hp from what people seem to think are maxed out from the get go.

your combo sounds like it has a smallish carb. throw a 950 hp and a victor junior. slowing the heads down should net you very good gains.

ive done 385" with ported sportsman II heads 2.055 intake similar cam but with a hurricane intake and a 950 make 565hp. no reason you couldnt be there
Indeed, fix the pinch, fix the turn, get them stable - easy gains.

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Re: Gains porting afr195 on sbc 388

Post by 68corvette » Sun Feb 09, 2020 4:47 am

To clarify, heads are Eliminator "Street", I think originally they were named as "Race Ready".
These have 2.05" intake valves.

Here are the flow numbers I measured:

Code: Select all

Lift    Intake     Exhaust   E/I%
0.1	66.1       62.6      94.8
0.2	145.9      113.2     77.6
0.3	197.9      160.0     80.9
0.4	241.5      192.4     79.7
0.5	269.1      208.9     77.6
0.6	263.6      213.4     81.0
0.7	261.5      209.9     80.2
Pushrod Pinch measured 1.90sq.in, so close to what PRH typed below.
Its not easy to measure accurately when the port is angling here and there and the min is not in same direction with pushrod.

Without raising the port I found it difficult to find much more area.
Pushrod side is thin, I did not want to go there.
Roof is already rising from entry, making there some ange from intake manifold. So I feel that that is not a good place to remove more material if entry is not raised.
Floor.. its straight as stock, so there is room for more area.. but with expense of port efficiency.
Divider wall was the spot to get most extra area.
I also re-machined the seats and worked on the shortside just to get the separation issues fixed.
Also I aimed to improve the streetability with the seat profile.
Exhaust side was not touched at all.

Code: Select all

Lift    Intake      Exhaust    E/I%   Gain%
0.1	65.8        62.6       95.2    -0.4
0.2	141.6       113.2      80.0    -3.0
0.3	197.1       160.0      81.2    -0.4
0.4	244.7       192.4      78.6    1.3
0.5	276.0       208.9      75.7    2.6
0.6	278.3       213.4      76.7    5.6
0.7	281.3       209.9      74.6    7.6
I did not want to break through the divider wall, and got the MIN to 2.12sq.in and runner volume now measures 205cc.
So flow decreased felow .4" lift and incresed 5.6% at max valve lift.
Runner volume increased 5%, so I think that "port energy" remained the same? :D

With the given combination,do you think I will gain anything?

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