Here's my input for what its worth. There's no way you'll make anywhere close to that without porting the heads and a single plane intake. I had a stock compression 430 engine with the middle sized Mutha Thumpr cam, headers and SP1 with self-ported Stage One 430 heads and was able to get down the quarter in the mid-13s in a 4600lb Riviera. That equates to roughly 440-460 crank horsepower with a small lift cam and stock rockers. Next motor was a 30 over 455 with the same heads, same lift but less duration cam, smaller diameter headers and mid-9 compression and ran low-mid 13s. Now, while neither of these combos came close to 500 crank hp, you can see where a little more compression (still pump gas friendly) a better cam and some roller rockers would easily have gotten me there on self-ported heads. The heads are where the power is and I'm sure mine would be considered atrocious by those who do it for a living but for my first attempt at ever porting and after close 80+ hours of work they seem to be doing pretty well. Oh and as for drive ability and mpg, with the 2004R trans, and ability to tune via wideband O2 sensor, I was easily seeing 18mpg highway with about 14-15 everyday city/highway driving. Plenty of vacuum with both cams to work the brakes.
The last one I built was 462, 67 430 big port heads fully ported, 10.6-1 TA 290-08hl Cam, HEI, TA intake and a 990 double pumper made 560hp and 570 tq.
Very nice!! Those are great numbers!! Great work, what a beast! Did you do the head work or out source it? If outsourced, when was that work done and do you care to share how much it cost and include the parts with that to keep the comparison in perspective? If you did it the head work, do you care to share how many hours you spent and do you have flow#'s for conversation sake? Keeping in mind for the OP, the tools needed to port not to mention a flow bench access if seriously dialing it in.... Other details to share to keep it all in a cost perspective? Cheers! MarkO
John Zerucha did the heads. hes staged70lark on this board I believe. he can probably answer the port questions. We used Ta headers and Harland sharp roller rockers. Anything else just ask.
Lots of good info, and it is clear that 500HP is unrealistic with iron heads. Is 400 HP too far off? 525ftlbs +/- more realistic? I have enough parts to put together an engine and the idea is to use what I have. Interesting thread none the less. If anyone knows of a good set of 430 heads near El Paso Texas I am interested. Willing to drive as far as Odessa,Lubbock or Albuquerque to pick up. Thanks in advance. Regards, 455NGLIDE
I disagree as stated we made well over 500 with Iron heads. Granted they were the best Iron head there is but still iron heads.
400 to 425 is usually not a problem with a mild cam , good valve job, round cylinders, and at least 9.5comp. Just keep in mind a 70 Stage engine made 375 to 385 honest hp with around a 9.7 to 9.8 to 1 from what ive always heard over the years, so unless you venture from that , to far thats what id expect
I stand corrected.... 500 HP has been achieved with iron heads,sure enough. Now; Would 400HP be more practical? Any body done this? I want to use parts that I have ( stock rotating assembly,iron heads,s-divider intake, 750 CFM Q-jet,headers-no cam yet) Back in the 80's I had a 430 that was rated at 365 HP from the factory, seems as though it shouldnt be too challenging to go beyond 400 with a 455 ...thanks again in advance. Regards, 455NGLIDE
If it meets the criteria I listed above yes 400 to 425 is very obtainable and been done hundreds and hundreds of times. I would suggest getting some undercut stem valves from TA, a quality valve job at the very least tho. That will go along way to ensure you get to 400+ without grinding on them
If it meets the criteria I listed above yes 400 to 425 is very obtainable and been done hundreds and hundreds of times. I would suggest getting some undercut stem valves from TA, a quality valve job at the very least tho. That will go along way to ensure you get to 400+ without grinding on them 10-4 on that...and thanks:beers2:. Looking forward to this build. Regards, 455NGLIDE
I have a set of '67 big valve heads sitting up in Ohio. I hope to get them down here in TX by April...
Once again those are very impressive and out if the ordinary numbers, for such a mild cam iron head combo Marv. I can only imagine the heads must have been some really nice pieces, and compression was probably on up there pretty good. Big carb,single plane, etc. The OP's question was if 500 was possible with pumpgas,sdivider,no MAJOR porting, mild cam etc
No one is saying you can't make 500 HP with iron heads, just that you need some well ported iron heads. You can do it with less porting, more compression, and a bigger cam, but the OP wants street ability also. Again, street ability means different things to different people.
And the answer to the original ? Is no its not possible given those parameters. The only reason I say this is because the last thing we need is guys reading this and thinking they can use stock untouched stuff and make 500hp then go to the cruise in and tell all their buddys and randoms that come by and actually have a true understanding of what it rakes to make HP, listen to them say making over 500hp when its lucky to make 400. Next thing you know we'll be like the mopar guys ha, "it makes 800hp" but only runs 12 s
Horsepower numbers above 500 for ported iron heads with a moderate cam and compression is the norm looking at 30 years of builds in the GS-X-Tra. We had Tomlenson street strip ported iron heads on a 11:1 engine make 560 HP and 580 TQ in the early 90s before any Stage One aluminum heads were available. Cheryl
Yup, we also had better gasoline in 90's. Would an 11:1 iron headed engine run on 93 E-10? Maybe, but you wouldn't be able to get on it much without worrying about detonation. I'll have to look at my past GS Xtras to see what exactly street/strip porting was:grin: Aluminum heads made making 500 + street friendly HP pretty easy comparatively.
Larry you know, as well as anyone, it is more about the dynamic compression and quench then the static compression. you can make a 14:1 static compression run on pump with the right cam. Come on man! Cheryl
