How hard is it to make 500 HP with a closed chamber/iron headed 455...using Poston S-Divider Aluminum intake and headers? Flat tappet cam & stock rods. Is it really necessary to invest in major port work on iron heads? Looking for good street manners and a reasonable degree of reliability. If it sounds close to stock all the better. Gonna have another big block built - gathering info from the best place possible-right here @V8Buick. Thanks in advance. Regards, 455NGLIDE
Not gonna happen, 500hp with stock heads = lots of compression and a big cam. Even with ported irons it will require over 10to1 and a pretty healthy cam, and trying make work with an Sdivider will only complicate things
Unless your up to doing some home porting on the irons, which porting iron is no fun at all I promise you. You will only be throwing good money out to bad, the time and money needed to get iron heads where they need to be to allow enough air to support decent hp without the help of huge cams and compression simply isnt worth it.
TA heads with lite bowl work or even box stock, with a 10.5 to 1 bottom end and basically any performance cam you put in it will make close to or over 500hp
We made 507hp with iron head and iron intake, but it is a 470 and is a pump gas power brakes car but being a 470 it does not have stock rods. JW also will get around 500 on his stock appearing iron head and intake 470. It can be done, but, I had to have Herche Performance build it for me. Troy
Want to make 500+ HP and have good street manners? Want it to sound stock or close to it? The answer is good head flow. With good heads, you can use a smaller cam, and still make good power. Good street manners, that means different things to different people. Want it to idle at 700-750 RPM in gear. Want it to get decent (over 10 MPG) gas mileage? Want to be able to get in and drive the car on the highway 200 miles for 3 hours if necessary? Want to be able to idle in stop and go traffic with temps in the 90's without overheating or fouling your plugs out? Want to be able to run on pump premium gas? If you answered yes to my questions, then your definition of good street manners matches mine. My aluminum heads flow 334/250 @ .600 lift. I use a smaller roller cam (230*/238*, 112*) My car can do all of the above. I have been driving my car down to Cecil County Dragway in Maryland every fall for 4 years now. Round trip is about 350 miles, 3 hours of highway driving. The car runs mid 11's and gets 15 MPG if I am careful.
You could run a lot more compression, but I'm not sure that would be worth more than better head flow. I think head flow is much more important than compression when making power. You would also be tied to using E-85, not as widely available as pump gasoline depending on locale. The OP wants good street manners and 500 HP.
Larry, I do believe that would be true. But, I have looked at flow rates in one of the board's Iron Head Flow numbers threads and I am not sure mine are anything besides just good, as many other sets flow better than mine at higher lift. Mine do seem to have really good low lift flow. Troy
why throw away money on iron heads if looking to get north of 500hp? As mentioned, it is attainable but in the end, unless you are equipped and tallented to do the work yourself, you will be well on your way and at least 60lbs lighter with a set of TASE Chris does. You will feel it in the butt dyno:TU::3gears: I have nothing to add regarding the S divider but again, the aluminum heads would overcome some of that if you use it. New stg1se ported heads http://www.v8buick.com/showthread.php?306638-New-stg1se-ported-heads
Here you go.. https://youtu.be/O796cb7JlYo Flat tappet, no porting version of this motor makes around 450 HP Roller cam no porting version- 475 Flat tappet, fully ported intake-heads- 500 Roller cam fully ported intake-heads aprox 525 All are possible, i have build one of each of the first three, all require compression ratio north of 12-1. All these were tested on race fuel. Expect a 5-10% loss in airflow (and power) if E-85 is used, due to the extra fuel in the mixture displacing air. All iron motors are considered "cylinder head limited", so anything done to reduce available flow in the heads, should result in reduced power. I have not tested this exact scenario, this is just a theory based on previous observations of cylinder head limited engines, when switching back and forth from gas to E-85 on the dyno. I would use a stock 70-71 iron manifold, rather than an S-Divider. JW
One of my big requirements was pump gas. I had to ask Gary, but mine is just a little bit above 10:1 compression and is going to run 93 gas. Troy
That is one of the really great things about aluminum heads, they dissipate heat much faster than iron. That makes them more octane tolerant. Depending on camshaft, you can run up to 11:1 SCR and the engine will run happily on pump gas. In fact, when going from iron heads to aluminum heads, you should increase your SCR by a full number to get the best from them. When I bought my TA heads, Greg Gessler milled them .040 to get my chambers down to 59cc. My compression went from 9.4 to 10.4:1. My current engine has 10.5:1. SCR isn't the only thing to consider when building a pump gas engine. Camshaft choice affects DCR. http://www.empirenet.com/pkelley2/DynamicCR.html
This is my iron headed roller cam 10.25:1 464 that dyno'ed at 598 HP 609 torque. Yes the iron heads are highly modified. If I didn't already have the heads I would have put some T/A heads on it. This is my street car and with some timing pulled out I run 93 octane but it really likes 100 with full timing in. I have since switched over to a FAST EZ EFI system for fuel management. BTW it is badass on the street.
Very impressive Alan making good hp thru manifolds is TOUGH, not many have done it especially with such low compression, them heads and cam combo are definitely getting it done.
