To the guys who either run a engine dyno or build engines proffessional a question.

[Huskinhano]

I hang out on a vintage Mustang board. Got a new guy that wants to get a little more power out of his C code 289 ( 2V carb, 9:1 CR). He just wants a nice running 289 for the street, nothing dramatic when he rebuilds it. One of the more experienced guys who restores them said to do a little head work, basic stuff, clean up casting flash, remove the bump in the exhaust port where they drill the AIR holes, a good dual plane intake, 600 CFM carb and a popular Ford 289 Cobra hyd cam with these specs, 288* advertised, 218* @ .050 .460" I&E and 113* LCA. This combo sounds like a good set up and I agree from a power and cost standpoint.

He said he knows some one who built one this way and made 323 HP @ 5300 RPM on a dyno. I don't have the experience to agree but I feel it's reasonable. The problem is other members who love spending other people's money and want to see aluminum heads, roller cams, 11:1 CR and so on. Not what this guy wants to do or needs. So the $64,000 question, is that 320 HP a good assumption and if you have built or tested a SBF similar to this, what did you get?

[Barry Donovan]

a 289 is the only engine where I saw the valley drop iunto the pan in pieces..

aluminum heads sounds good, going for 300hp...
I 'd go even less.
600cfm is nice too. as original. why risk.

[DanStokes]

Of course, I didn't do that type of dyno work - but in my experience estimating HP is tricky at best. I'd go to those HP estimator programs and run the combo thru several. If they tend to agree then it's likely a fair guess. Those programs are generally (depending on who wrote the program) a compilation of a number of builds worth of experience and have a reasonable chance of being in the ballpark.

Remember to watch out for the RPM at which the power is generated. If the program estimates the desired HP at 10,000 rpm it really isn't usable for a driver.

Dan

[Deaf Bob]

I'd say a motor don't care who's name is on the parts in the guts...
That said, build for torque..
The logic behind a 2 barrel vs 4 is a 600 cfm 4 barrel is running 300 cfm most of the time instead of 350 (or whatever the stock 2 barrel is) then you got 300 more cfm for "play".
Dual plane manifold is required..
The package sounds like it will wake that engine up nicely and still be a daily driver if he wants..
I tend to not believe "claimed" numbers... Might be so..
Know a guy who claimed 415 hp.. Drove quick and won alot of stop light battles.. When he dyno'd it ... He had 275 hp!

[Caveman Tony]

Desktop Dyno says that combo roughly 280 hp @ 5k rpm, but a healthy 354 lb-ft at 3500.

Would make for a real fun cruiser, plenty to enjoy & enough to burn some rubber.

Ignore the knuckleheads that want 11.5 CR. Its not their car, and it'd be a PITA for what he wants to do with it.

[Beagle]

331 isn't all that expensive, he would probably appreciate the torque. 320hp out of a 289 might be a little "peaky". 320hp out of a 331 is pretty mild. fwiw. If he's going for pistons and such already, it's about the same price.

Probe has 20.1 cc dish 331 pistons that would be roughly 9.1:1 with the 289 heads, should be a torquey little guy. 212-218* intake cam, performer, headers, you should be close. 300 hp would be realistic with the 331, the 289 everything would have to be perfect and I'd say closer to 6000. Depends on who does the heads would be my comment.

[BBR]

323hp would be 1.11hp/c.i. I call BS especially at only 5300rpm

[Beagle]

5300 is the trick, 323 foot pounds at 5300 isn't totally out of the question? That'd be a premium gasoline engine with old Ford heads would be my bet... would take more than 9:1 and I'm pretty sure you're gonna have to do more than clean up the thermactor bump. Everything would need to be perfectly right. 302's pull 300 ft pounds but dang sure not at 5300.

I'd at least reach for a 302 crank and a roller cam for a truck, something like the 258 XE comp or Crane 2020 if you can find one. For what it costs to rebuild the 289 heads.. I'd be tempted to dirt ball out a late model 302, clean up the heads, same deal. They are fun little mills.

/edit - I think I'm on crack. I'm having a very tough time with any stock intake port 289 head going 320hp with a 218* cam and 289" - and making 350 foot pounds @ 3500 ?? That is similar to the 271hp cam, I think it's smaller?

He's quoting somebody else's dyno sheets.. I'd believe this from a 331 or a 347 though. I'm gonna go find the rest of that build, something ain't right.

[Huskinhano]

The guy who made the post about the HP numbers is generally a pretty solid guy, not one to make claims. He also works in a Mustang restoration shop. He is quoting some one else. I'm not saying he's right but he does supply the material to back up what he is saying. Here is a link, look about 6 posts down to chriss66dad who is quoting the same info and posts a dyno print out. A little small but it does say 323@5300. While I don't have the experience to say one way or another, my guess on HP for the combo would be about what Caveman said. Who knows? Maybe an optimistic dyno? The heads were not stock but nothing really major done, just cleaned up the exhaust ports a little. I do like the cam selection.

http://www.moddedmustangs.com/forums/classic-mustangs/210218-how-can-i-make-my-289-1968-coupe-go-faster.html

[yellomalibu]

I am certainly not what you would think of as an engine builder, but I've assisted in a lot of engine building and have read a good bit about it.
From what I've read - the best place for an amateur to spend time on a stock set of heads is directly over the valve, "pocket porting". Be careful not to hit or get too close to the valve seat. Cleaning up casting flash and even gasket matching is said to give minimal performance gains - but if you're already there with the carbide bit and the die grinder, go for it.

[JeffMcKC]

put a 160.00 gear in the back it will add more power than working on the engine ever thought of

[Beagle]

put a 160.00 gear in the back it will add more power than working on the engine ever thought of

sage words. 4.10's and an AOD make a new car out of it if he can swing the AOD.

[milner351]

1. cam sounds small, which is fine if he wants to keep it a mild cruiser with good idle vac, and not worry about springs.
2. why mess with old heads when GT40's are better, have hardened seats and don't cost much more than a run of the mill valve job?

The HP prediction is high, that sounds like a torque number to me, or - if the combo was ever dyno'd - some one got lucky with the porting and the dyno was an optimist.

[Huskinhano]

1. cam sounds small, which is fine if he wants to keep it a mild cruiser with good idle vac, and not worry about springs.
2. why mess with old heads when GT40's are better, have hardened seats and don't cost much more than a run of the mill valve job?

The HP prediction is high, that sounds like a torque number to me, or - if the combo was ever dyno'd - some one got lucky with the porting and the dyno was an optimist.

Looks like peak torque was 358 ftbs @4200. I don't know what to think other then he got lucky or something. The problem with the GT40 heads on a 289 is that the CR would be in the crapper. The 289 head is 55 CC and the GT40 is 65 CC. While the low po 289 has an advertised CR of 9.3:1 is exactly that, advertised. I have a 289 C code short block. The head is 55 CC, the pistons have a 13CC dish. Add in a couple of CC for the head gasket and a few more for the piston being down the hole a modest amount and suddenly you got a low 8:1 motor! The GT40 head would bring it down to low 7's.

[Silver68RT]

Looks like peak torque was 358 ftbs @4200. I don't know what to think other then he got lucky or something. The problem with the GT40 heads on a 289 is that the CR would be in the crapper. The 289 head is 55 CC and the GT40 is 65 CC. While the low po 289 has an advertised CR of 9.3:1 is exactly that, advertised. I have a 289 C code short block. The head is 55 CC, the pistons have a 13CC dish. Add in a couple of CC for the head gasket and a few more for the piston being down the hole a modest amount and suddenly you got a low 8:1 motor! The GT40 head would bring it down to low 7's.

I've got that problem on the 390 in my '68 Mustang GT right now. Somebody put in some cut down TRW pistons meant to be used with a 428 crank, 390 rods, and 390 block. Problem is, they used a 390 crank. The best case scenario is 7.5:1, add in some valve reliefs and pistons further than 0.2" down in the hole, and it's only going to get worse. I've got no vacuum. If I crank in some advance on the distributor I can get it to 5", but then it won't start.