Just curious on HP gains with this 289 mild combo

fasttback · Dec 29, 2005

I was recently asked how much HP is my '66 289 is producing and I guessed somewhere around 250-275? (Ford's unmodified est is 225). Since some manufactures est can vary quite a bit, I just want to see what the forum's experts say (or anyone who feels like voicing there opinion). This post is just for fun and to see what components add what.

Here it is:

1966 289 A-code (rebuilt stock a few years ago - has good compression on all cylinders). If it's not mentioned below, it probably stock.

The modifications:

bottom end stock (except windage tray)

heads E6's ported (gasket matched) I and E with bowls and chambers cleaned up/smoothed to help with flow and shrouding issues. It looks like the previous owner installed 1.84" intake valves slightly trimmed down. (I know these heads are not the best, but I got them cheap...really cheap).

roller rockers - ratio 1.72

Edelbrock performer intake manifold - gasket matched.

1" 4-hole phenolic spacer

Road Demon 650 vacuum secondaries

Tri-y's with 2.25" mandrel bend exhaust, x-pipe, turbo mufflers (exhaust runs to rear of car)

Mallory electronic ignition with msd blaster 2 coil.

The idea of the mods was to make the car respond nice off idle (0-4800 rpms) and it seems to work. I do believe the carb and spacer is little much for the current setup (my old Holley 600 seems to respond better all around - waiting for rebuild).

D.Hearne · Dec 29, 2005

With E6 heads on there, you've lost a LOT of compression. Those chambers are like 14 cc's larger than a 289's 54cc heads. Any gain you might have realized was probably lost with the decrease in compression. I wouldn't guess it had any more power than the factory rating. I did the math and instead of having a 289 with 9.0 to 1 compression, you now have a candidate for supercharging, cause the ratio is now about 7.5 to 1 .

fasttback · Dec 29, 2005

D.Hearne said:
With E6 heads on there, you've lost a LOT of compression. Those chambers are like 14 cc's larger than a 289's 54cc heads. Any gain you might have realized was probably lost with the decrease in compression. I wouldn't guess it had any more power than the factory rating. I did the math and instead of having a 289 with 9.0 to 1 compression, you now have a candidate for supercharging, cause the ratio is now about 7.5 to 1 .

Yea, I know I was going to lose some compression, but not that much. Actually the stock A-code 289 has between 9.8-10.0 to 1 compression. The rebuild still used the flat tops so I know the compression was around stock. I also tried to cc the E6 heads before I installed them. I got around 64-65 cc's in a few chambers, so maybe they were milled? or I still need to learn more about cc'ing heads. I estimated around 8.6-8.8 to 1 on the compression. Good for today's gas!

D.Hearne · Dec 29, 2005

Your actual ratio will also depend on what pistons are in there. Many 289/302 pistons use one of two basic comp heights. One is 1.585, the other 1.605. Even that small .020 difference in heights makes a big difference in the ratio on a small displacement engine like a 289. Assuming that your's does have a zero deck clearance, that gives you an 8.6 to 1 ratio at best. With the 1.585 pistons, you've got an 8.2 to 1 motor. Todays gas will tolerate much more than many think. My 331 with it's 10.4 to 1 ratio is Ok with 90 octane gas. Ditto for my 68 Merc's 390 ( 10.25 to 1) In my opinion you'd be better off with the original 289 heads. And stand by my estimate of a near zero sum gain over stock with your combination.

rbohm · Dec 29, 2005

first you have to realize that that ford calculated the 289's compression ratios on blueprinted engines. thus the production compression ratios are going to be different depending on the piston used. flattop pistons are rated at 10:1, but usually produced more like 9.5-9.8:1 compression. there was also a dished piston that was rated at 9.5:1, but produced more like 9.0-9.3:1 compression. figure that the 14cc difference in combustion chamber size is going to cost you about 1 point in compression, so you are looking at like 8.5:1 compression.

now also remember that the "A" code engines factory rating is 225hp, but that is sae gross hp. net is somewhere down around 175-185hp, and your combo should make around 200, 210 at best since everything is basically stock, even with the ported heads. you can make this motor pop by adding a supercharger and set the boost pressure up around 9psi, about the outside limit on 91 octane. or you can add a comp cams 270h cam along with a set of world products windsor jr heads with 58cc combustion chambers. that should bring you up to around 250-275hp depending on your tuning abilities.

68RustBucket · Dec 30, 2005

I don't really understand your reasoning for putting E6's on any motor. They are, flat out, some of the most awful heads ever put on a windsor. Ford replaced the E7's with them, then realized the E7's were much better and therefore took the E6's out of the picture. But even with E7's, you'd be in the gutter with lower than desired compression for a N/A motor. Best bet for you is to get some 289 heads and get them ported with larger valves. They can be built to flow better than GT40's if done correctly, and you'll have much better compression. Those heads are really killing the motor's potential

Max Power · Dec 30, 2005

You won't even approach 1hp per cubic inch without much better heads. Rather than rehabbing or porting the crap out of any Ford casting, I would look for decent used aluminum performance heads. There is no shortage of people who step up to bigger heads for more radical builds and sell their old heads on ebay and the like...

57fairlane · Dec 30, 2005

68RustBucket said:
I don't really understand your reasoning for putting E6's on any motor. They are, flat out, some of the most awful heads ever put on a windsor. Ford replaced the E7's with them, then realized the E7's were much better and therefore took the E6's out of the picture.

Yes and No.

The E6 heads are awful in stock form . If you are a decent porter, they can flow as well as E7 heads provided you know where to port. The main issues have been brought up for years: The combustion chamber blows, short side radius of the exhaust isn't so hot. However, once "fixed" the are a very decent head for a factory piece. The main draw of messing with the E6 head is that the valves sit up so much higher in the head than the E7 piece. The valves sit roughly .035" farther up into the head.

fasttback · Dec 30, 2005

Wow! Everyone hates my E6 heads, but remember the original intent of the quick top end build on this motor was to make it responsive at the lower-mid rpms and not top end. I was not searching for E6's when I bought them - they were just a deal at the time. By the way...one of the best comments I've heard about these heads is that "they would make a good door stop." Don't worry, I still have my ported C9 Windsor heads w/ 1.9 and 1.6 and plan to buy AFR's 185 or Roush 200 for my 352 (302 stroked 3.4 at .060 over). I would have bolted the Windsor heads (and will do it some day), but I just started porting these back then and I needed heads right away.

I would agree with everyone that there are many other factory heads that will out perform the E6s (usually occurring at the higher rpms). These heads are not as bad as people think. They do provide a good response and torque at lower rpms. Remember on the street we are not at 5000+ rpm most of the time. I have read all the problems associated with these heads and tried to cleaned up these areas as best as I could (mainly the intake valve shrouding problem). My other concern was the loss of compression that bothered me the most...and still does. These heads are just a temporary solution that will be replaced by the Windsors.

As a note: after the modifications initially mentioned, the car is more responsive and pulls harder than its stock configuration, but will die hard after 5000 rpms (prob. cam and shrouding issues). I would not recommend these heads for most applications, unless you have a work truck and do not want to spend more than $100 on someone else's rebuilt heads.

D.Hearne · Dec 30, 2005

57fairlane said:
Yes and No.

The E6 heads are awful in stock form . If you are a decent porter, they can flow as well as E7 heads provided you know where to port. The main issues have been brought up for years: The combustion chamber blows, short side radius of the exhaust isn't so hot. However, once "fixed" the are a very decent head for a factory piece. The main draw of messing with the E6 head is that the valves sit up so much higher in the head than the E7 piece. The valves sit roughly .035" farther up into the head.

.035 higher ? More like 1/8" ( .125") Thats how much shorter the valve stems are than E7 valves. Also the reason the std 5.0 these came on after they were used on the 86 Stangs didn't have valve reliefs in the pistons.

D.Hearne · Dec 30, 2005

fasttback said:
Wow! Everyone hates my E6 heads, but remember the original intent of the quick top end build on this motor was to make it responsive at the lower-mid rpms and not top end. I was not searching for E6's when I bought them - they were just a deal at the time. By the way...one of the best comments I've heard about these heads is that "they would make a good door stop." Don't worry, I still have my ported C9 Windsor heads w/ 1.9 and 1.6 and plan to buy AFR's 185 or Roush 200 for my 352 (302 stroked 3.4 at .060 over). I would have bolted the Windsor heads (and will do it some day), but I just started porting these back then and I needed heads right away.

I would agree with everyone that there are many other factory heads that will out perform the E6s (usually occurring at the higher rpms). These heads are not as bad as people think. They do provide a good response and torque at lower rpms. Remember on the street we are not at 5000+ rpm most of the time. I have read all the problems associated with these heads and tried to cleaned up these areas as best as I could (mainly the intake valve shrouding problem). My other concern was the loss of compression that bothered me the most...and still does. These heads are just a temporary solution that will be replaced by the Windsors.

As a note: after the modifications initially mentioned, the car is more responsive and pulls harder than its stock configuration, but will die hard after 5000 rpms (prob. cam and shrouding issues). I would not recommend these heads for most applications, unless you have a work truck and do not want to spend more than $100 on someone else's rebuilt heads.

If it's any consolation, you were going in the right direction on the E6's having better bottom end, just that as you've seen now, the loss in compression is a bad trade-off to get that. Put the Windsor's on it. At least with them, you'll gain back some of the compression and have larger valves to boot. Put a wide LCA cam in it and that'll help build the dynamic compression to help in that regard.

stang302v8 · Dec 30, 2005

man, just slap a 3/4 race cam in there, put your stock 289 heads back on with the 1.7 rockers, if its automatic put a 3200 stall and 3:50 gears, if its stick slap 3:90's in that beast, and rock and roll

fasttback · Dec 30, 2005

D.Hearne said:
If it's any consolation, you were going in the right direction on the E6's having better bottom end, just that as you've seen now, the loss in compression is a bad trade-off to get that. Put the Windsor's on it. At least with them, you'll gain back some of the compression and have larger valves to boot. Put a wide LCA cam in it and that'll help build the dynamic compression to help in that regard.

D.Hearne you've read my mind about the future upgrades for the engine. During the modifications my friend kept pushing the cam idea too. This engine build was a nice experiment and it performed like it was suppose to, but now I guess it's time to wake her up!

57fairlane · Dec 30, 2005

D.Hearne said:
.035 higher ? More like 1/8" ( .125") Thats how much shorter the valve stems are than E7 valves. Also the reason the std 5.0 these came on after they were used on the 86 Stangs didn't have valve reliefs in the pistons.

Well then where did I come up with .035 then?

.035 more clearance than the E7s on the stock pistons?

Oh well crapola

D.Hearne · Dec 31, 2005

I've compared the valves from both, side by side. While I don't recall the actual measurement ( it's been about 3-4 years since) the difference was about 1/8 inch. And both use the same pushrods, so to keep the geometry correct, the E6's would have been that amount deeper in the head.

D.Hearne · Dec 31, 2005

stang302v8 said:
man, just slap a 3/4 race cam in there

Where do you find these now-a-days?

Max Power · Dec 31, 2005

D.Hearne said:
Where do you find these now-a-days?

Probaby JC Whitney still has em!

D.Hearne · Dec 31, 2005

Max Power said:
Probaby JC Whitney still has em!

In all my years of fiddling with this stuff, I've yet to find someone who could actaully tell me just what the specs were for a "3/4 race cam"

ashford · Dec 31, 2005

e6 heads do have their use. say you want a power band from 1k-5k rpm that would be my choice of head(plus mentioned work)i built a 302 for my capri(e303, e6 heads unshouded valvesbored the hell outa the exhaust prots bolw blending etc, weiland action plus intake(already had it dont make fun of me), speed pro coated pistons (figured 7.5-8:1 compression), cheapie 15/8 headers, hooker supercomp exhaust system, holley 600 and accel 300+ spark box. it got me a high 13 quarter at 97mph. spin the tires anywhere in first gear(t-5 from 4 cyl) and break traction in 2nd on concrete above 3000rpm.the engine would puke about 5500rpm. later i ported and 289 heads and installed 1.94 1.50 valves then and upgraded to a stealth intake. i lost so much low end it was sickening. on the plus side above 4800 rpm or so the 289 heads took over making a very rpm friendly engine which equals more hp but overall performance wasnt much better about .5 sec and 4 mph in the quarter.

Just curious on HP gains with this 289 mild combo

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