AFR 165 heads replacing gt40p ported

[homerojr]

As it´s normal when we got infected by the power virus, I think my car has become slow... My heads are ported and polished, and I´ve picked probably at least 40 hp over the stock heads (not adding the gains obtained with headers, MAF, intake, cam, rr, full exhaust). My question is how many more hp can I expect just by adding AFR 165 heads? According to 09/2003 MM & FF, there was an increase of 30hp using the stock p´s over the stock heads and 90+ hp using AFR 165 over stock. Can I expect 50hp or so?
I don´t have any dyno sheet, but I guess the engine now produces 300 honest hp.
Any comments would be greatly appreciated

 

[red94fiveo]

I would think that you would have a noticable difference with the AFR's over the p's. Im not sure what you mean by 300 'honest horsepower', but with the AFR's you should have about 300 at the wheels.

 

[Joes95GT]

First, let me ask about your cam? What are the specs for it. Next, what type of intake are you running? Ported and polished GT40P heads will run right with box stock AFR's as long as the right cam is used. I'm not dissing AFR's at all, I just think that the potential of the GT40P head is brushed under the carpet because of two reasons: 1) it's an iron head with smaller valves, and 2) because it's a Ford product. With the right cam, and right intake manifold, you should be right around ~290 horsepower. With the AFR's, the right cam and the right intake, you will be right around ~300 horsepower.

Let us know what the specs of the cam are, and what intake you are using. Your best bet would be to change the cam and (maybe) have the intake ported, chances are, your car is under cammed. In your case, I don't think the extra $1500 spend would be a wise decision for the MAYBE 15 horsepower that would be picked up. I honestly don't think you would see an increase of 15 horsepower. I am a firm believer in the GT40P heads and I know many others that know their true potential are too.

Joe

 

[GTJake]

Got any flow numbers from the ported and polished P heads? Maybe play with some different things in your combo....underdrive pulleys, long tubes, tune...etc.

Jake

 

[95snoozer]

Id say maybe 15-20 RWHP gain.

 

[95snoozer]

GT-40P Cast Iron
I
1.84 valves
.100-61
.200-128
.300-169
.400-195
.500-196
.600-193
-
Stock
Super Ford - May 1999

GT-40P Cast Iron
E
1.46
52
90
123
135
139
142
-
Stock
Super Ford - May 1999

GT-40P Cast Iron
I
1.84
65
124
173
203
207
203
-
Stage 1
Super Ford - May 1999

GT-40P Cast Iron
E
1.46
58
102
139
159
162
169
-
Stage 1
Super Ford - May 1999

Air Flow Research 165cc
I
1.90
-
123
186
225
250
250
-
-
Stock
AFR Catalog - 1998

Air Flow Research 165cc
E
1.60
-
118
153
178
185
191
-
-
Stock
AFR Catalog - 1998

 

[zenboy99]

You will most likely have a much nicer torque curve with the AFR-165's since the ports would most likely be alot smaller. I know the AFR-165 ports are alot smaller then the GT-40X heads and the AFRs still flow alot better.

 

[muh'stang]

http://www.allfordmustangs.com/Detailed/630.shtml go there you can compare the head flow.

 

[zenboy99]

Off topic, but interesting.

98 Cobra heads outflow 99-01 Cobra heads, and AFR-165's outflow both of those.

 

[homerojr]

Thanks for your interest in this topic. My cam is a Compcam 270 276 218 224 .512 .512 114 lsa. I got a cobra intake ported and polished gasket matched, unequal shorties, BBK o/r h pipes, MAC exhaust, Pro-M 77, Ford 65 tb and 3:73 rear. The engine idles nicely lumpy at 850, revs readily past 6000, and I haven´t even touched the EEC IV yet. I´m a firm believer on the p´s potential, and I´m very satisfied, but I also know the AFR´s have more potential (although at double the price).

 

[Joes95GT]

You actually have a very nice cam for that set up because the P's flow best around .480" lift, and you've had them ported so they probably flow best at ~.520", and your cam does a pretty good job of covering that. In this case, I wouldn't waste your money on AFR's. The torque curve of an engine is dependent upon many things, however, the most important thing is velocity. AFR's produce an excellent torque curve, however you need a big cam to support it. With the cam that you are running now, the GT40P heads will have a better torque curve than the AFR's because that cam is better suited for the P style heads. I understand your need for speed, but in all seriousness, I would be extremely surprised if you would find 15 more horsepower from the AFRs. So, that money you had set aside of cylinder heads - go out and buy nitrous or keep saving for a blower because in this case, AFR's are not worth it.

Joe

 

[homerojr]

Thanks a lot for your explanation, Joe.I´m not surprised the combination is working so good, before choosing the cam, I´ve been researching for almost a year in this forum, Corralnet, magazines, and with the help of all of you, I was able to pick this combo, keeping the cost relatively low.
I haven´t had the opportunity to take it to dyno or track, but the car feels really strong from 2000 to 6000.

 

[Joes95GT]

No problem. I just hate when people diss on Fords aftermarket division. IMO, a car powered by all SVO parts will run right with a car powered by some of "the best" aftermarket parts around. Sure AFR is a great head, I was just pointing out that P heads are the best budget head, hands down, and some people don't realize it. They think that just because it is AFR, it is going to make an improvement, when in actuality it really doesn't (in your case).

Joe

 

[rio95]

Are Your Mac Headers Shorties Or Longtubes? Do They Make Any P Longtubes? Bbk? Do You Know How Much They Are? I'm Am Interested, B/c I Have Thought About Getting A Very Similar Set-up To What You Have Now. Also, I Agree. Why Would You Waste All That Money For No More Than 20 Horse? That Would Be Rediculus In My Opinion.

 

[GTJake]

Are Your Mac Headers Shorties Or Longtubes? Do They Make Any P Longtubes? Bbk? Do You Know How Much They Are?

Regular MAC long tubes work with P heads.

Jake

 

[rio95]

i have heard that regular bbk longtubes work too, but you need to get differnt plug wires. aren't there specific headers? i have heard that there are shorties, but i have never heard about longtubes. if there are p bbk longtubes and they are around the same price, i will probably go that route.

thanks

sorry if i'm a little off topic.