Jon Kaase SR71 Cylinder Heads

jonkaase wrote:


I know this is pretty much unbelievable, but this went past our goal. First sheet is with cam at 113, second is at 116. Timing at 28. It took 5 runs before these sheets to get the carbs right. 6 cylinders were way rich and the front two needed fuel. It would be hard to figure out without all 8 O2 sensors on the primary pipes. Special thanks  to Billy Godbold at Comp Cams for making 2 new lobes for me. This engine has 179 gram steel intake valves, stud rockers with no stud girdle, and Manley Nextek dual springs with 250# on the seat and 750# open. Trend 3/8 pushrods, .135 wall.  It still sounds like it wants more at 8100. Since we were going over 8000 rpm I started it a little higher than the other runs. Peak torque was below the starting RPM.

Wow, just awesome results. These heads seem to be an outstanding choice.

Got my set from Jon last week and had them cut down to 65cc.If one was to do some minimal port work with the best return on time would that be on the guide boss , as in possibly shorten it some and narrow it and transition it into the bowl area? Thanks

fordsrgrt wrote:Got my set from Jon last week and had them cut down to 65cc.If one was to do some minimal port work with the  best return on time would that be on the guide boss , as in possibly shorten it some and narrow it and transition it into the bowl area? Thanks

I sent you a PM fordsrgrt.. like the user name....

I got my 71's installed now waiting for the 2019 season.
If you are on the fence with these I can tell you that they are quality pieces. The stud bosses are tall to keep the rocker body closer to the base of the stud reducing the side force moment on the stud.
I will compare with other heads from track data and report here in the spring.

Dave De wrote:I got my 71's installed now waiting for the 2019 season.
If you are on the fence with these I can tell you that they are quality pieces. The stud bosses are very to keep the rocker body closer to the base of the stud reducing the side force moment on the stud.
I will compare with other heads from track data and report here in the spring.

You didn't waste any time! Out of the box or did you tweak them any?

jbozzelle wrote:

Dave De wrote:I got my 71's installed now waiting for the 2019 season.
If you are on the fence with these I can tell you that they are quality pieces. The stud bosses are very to keep the rocker body closer to the base of the stud reducing the side force moment on the stud.
I will compare with other heads from track data and report here in the spring.

You didn't waste any time!  Out of the box or did you tweak them any?

Straight out of the box. The ports were close enough I didn't touch them. I am waiting on Jomar to finish the girdles but I wont need them until April.

Dave De wrote:

jbozzelle wrote:

Dave De wrote:I got my 71's installed now waiting for the 2019 season.
If you are on the fence with these I can tell you that they are quality pieces. The stud bosses are very to keep the rocker body closer to the base of the stud reducing the side force moment on the stud.
I will compare with other heads from track data and report here in the spring.

You didn't waste any time!  Out of the box or did you tweak them any?

Straight out of the box. The ports were close enough I didn't touch them. I am waiting on Jomar to finish the girdles but I wont need them until April.

Looking forward to the results...

68formalGT wrote:

dfree383 wrote:

enginetech wrote:Maybe (finally), a worthy competitor to the SR-20?  Though we will play hell getting it approved for use in those limited classes requiring “conventional” heads, whatever the hell that means.

How conventional can they be if the factory valve covers and intakes wont even fit????

brodix.com/heads-2/big-block-chevrolet-compatible-heads/sr-20-series-cylinder-heads20

Anything they can claim so they have a head to compete with the A460's in X275

Who is they? Brodix? I'm pretty sure they don't care one way or another whether some heads they produce are X275 legal or not. Especially not enough to essentially lie about what they are, at least from your perspective. Donald Long didn't decide those were conventional and force Brodix to call them that so they could run in his races. So who is they? John Sears who makes the rules for X275? He didn't have anything to do with that head, either, AFAIK. Maybe you meant Slick Rick? But I'm sure he likely doesn't care if it's legal, either. So? Who is they? Lol

MidnightbluS10 wrote:

68formalGT wrote:

dfree383 wrote:

enginetech wrote:Maybe (finally), a worthy competitor to the SR-20?  Though we will play hell getting it approved for use in those limited classes requiring “conventional” heads, whatever the hell that means.

How conventional can they be if the factory valve covers and intakes wont even fit????

brodix.com/heads-2/big-block-chevrolet-compatible-heads/sr-20-series-cylinder-heads20

Anything they can claim so they have a head to compete with the A460's in X275

Who is they? Brodix? I'm pretty sure they don't care one way or another whether some heads they produce are X275 legal or not. Especially not enough to essentially lie about what they are, at least from your perspective. Donald Long didn't decide those were conventional and force Brodix to call them that so they could run in his races. So who is they? John Sears who makes the rules for X275? He didn't have anything to do with that head, either, AFAIK. Maybe you meant Slick Rick? But I'm sure he likely doesn't care if it's legal, either. So? Who is they? Lol

No one here even cares who "they" are. The facts are all that matter and whoever claims, or whoever doesn't claim, one thing or another simply makes no difference in the end; only the reality.

MidnightbluS10 wrote:

68formalGT wrote:

dfree383 wrote:

enginetech wrote:Maybe (finally), a worthy competitor to the SR-20?  Though we will play hell getting it approved for use in those limited classes requiring “conventional” heads, whatever the hell that means.

How conventional can they be if the factory valve covers and intakes wont even fit????

brodix.com/heads-2/big-block-chevrolet-compatible-heads/sr-20-series-cylinder-heads20

Anything they can claim so they have a head to compete with the A460's in X275

Who is they? Brodix? I'm pretty sure they don't care one way or another whether some heads they produce are X275 legal or not. Especially not enough to essentially lie about what they are, at least from your perspective. Donald Long didn't decide those were conventional and force Brodix to call them that so they could run in his races. So who is they? John Sears who makes the rules for X275? He didn't have anything to do with that head, either, AFAIK. Maybe you meant Slick Rick? But I'm sure he likely doesn't care if it's legal, either. So? Who is they? Lol

"They".....the collective Chevy guys who only want to see their brand come out on top.

HorsinAround wrote:

How's that popcorn taste?

MidnightbluS10 wrote:

68formalGT wrote:

dfree383 wrote:

enginetech wrote:Maybe (finally), a worthy competitor to the SR-20?  Though we will play hell getting it approved for use in those limited classes requiring “conventional” heads, whatever the hell that means.

How conventional can they be if the factory valve covers and intakes wont even fit????

brodix.com/heads-2/big-block-chevrolet-compatible-heads/sr-20-series-cylinder-heads20

Anything they can claim so they have a head to compete with the A460's in X275

Who is they? Brodix? I'm pretty sure they don't care one way or another whether some heads they produce are X275 legal or not. Especially not enough to essentially lie about what they are, at least from your perspective. Donald Long didn't decide those were conventional and force Brodix to call them that so they could run in his races. So who is they? John Sears who makes the rules for X275? He didn't have anything to do with that head, either, AFAIK. Maybe you meant Slick Rick? But I'm sure he likely doesn't care if it's legal, either. So? Who is they? Lol

Do you post on Yellow bullet under the same name,if so are you a Chevy guy trying to p## people off on here with you first post?

Great thread, thanks for all the hard work.. i was toggling between afr and p51s. Called lem and got the p51s for my 557. Excited to get it on the water now...

I’ve seen it asked a couple of times in this thread and I understand that nobody really wants to say whether or not they are better than the a460 heads. I’ve read here and there that the sr 71 is going to put a big hurt on the sales of the a460, and that is possible, but from what I’m seeing, and please done take this as disrespect or anything like that, these new heads are awesome and Kaase is the man, but looking at the specifics of this build, I believe that is Kaase took the a460 and worked them to their potential and built a similar engine with over 16:1 compression, comparable intake,cam and carb there’s no doubt that he could best 1250. There’s already a few 1200+ hp a460 deals out there. I bet if Jon wanted to build max effort a460 deal he could get north of 1300+. Most of the 598 a460 deals that I’ve seen and I’m modeling mine after, are basic 360cc cnc heads, 13/14:1, single carb and .750 to .800 lift solid rollers that easily make 1000+ hp fairly straight forward builds and I think that’s what this engine is being compared to. Again these heads are awesome but I still think an a460 head still has the edge. But to be perfectly honest I don’t have a clue compared to many of the guys here and I would like to hear some thoughts

Mikejc wrote:I’ve seen it asked a couple of times in this thread and I understand that nobody really wants to say whether or not they are better than the a460 heads. I’ve read here and there that the sr 71 is going to put a big hurt on the sales of the a460, and that is possible, but from what I’m seeing, and please done take this as disrespect or anything like that, these new heads are awesome and Kaase is the man, but looking at the specifics of this build, I believe that is Kaase took the a460 and worked them to their potential and built a similar engine with over 16:1 compression, comparable intake,cam and carb there’s no doubt that he could best 1250. There’s already a few 1200+ hp a460 deals out there. I bet if Jon wanted to build max effort a460 deal he could get north of 1300+. Most of the 598 a460 deals that I’ve seen and I’m modeling mine after, are basic 360cc cnc heads, 13/14:1, single carb and .750 to .800 lift solid rollers that easily make 1000+ hp fairly straight forward builds and I think that’s what this engine is being compared to. Again these heads are awesome but I still think an a460 head still has the edge. But to be perfectly honest I don’t have a clue compared to many of the guys here and I would like to hear some thoughts

For me and the racing I do it's about the rules. In mud racing they can be strict about what can be ran in some classes and the SR-71 fits into a class where factory style intake and exhaust manifolds must be able to bolt on and function, not that you have to use them. I think this head gives you the benefits of an A460 height raised port but still allows the factory style parts to be used.

I hear ya in all that and I totally agree that’s the head I would go with in that case also. Hell if they’d have been out at the time I may have chosen them for my i build also. But I’ve seen on a couple of other sites where guys have said that the sr 71 is outperforming the a460 head on on more simple builds and just from what I have seen I’m not sure I agree. I’ve actually seen very few a460 builds of this nature because most guys looking for 1200 just go with the c head to begin with. But 1000-1100 hp a460 builds have been common over the years on basic ish builds and I just think that if one were inclined to really test the a460 head on a more max effort types of build one could crest 1300+ with similar parts as this. Jon definitely could

I hear ya in all that and I totally agree that’s the head I would go with in that case also. Hell if they’d have been out at the time I may have chosen them for my i build also. But I’ve seen on a couple of other sites where guys have said that the sr 71 is outperforming the a460 head on on more simple builds and just from what I have seen I’m not sure I agree. I’ve actually seen very few a460 builds of this nature because most guys looking for 1200 just go with the c head to begin with. But 1000-1100 hp a460 builds have been common over the years on basic ish builds and I just think that if one were inclined to really test the a460 head on a more max effort types of build one could crest 1300+ with similar parts as this. Jon definitely could

What most people don't realize is that the "out of the box" A460 platform is over 30 years old.

Many places have improved and still can further improve this head in many different ways so, the simple A460 power comparison is just not viable to make.

rmcomprandy wrote:What most people don't realize is that the "out of the box" A460 platform is over 30 years old.

Many places have improved and still can further improve this head in many different ways so, the simple A460 power comparison is just not viable to make.

Sure enough. The A460 heads have not had the evolution of the SCJ/P51/SR71 program.

Lem Evans wrote:

rmcomprandy wrote:What most people don't realize is that the "out of the box" A460 platform is over 30 years old.

Many places have improved and still can further improve this head in many different ways so, the simple A460 power comparison is just not viable to make.

Sure enough. The A460 heads have not had the evolution of the SCJ/P51/SR71 program.

Maybe not yet but if and when the new A460 head is finished from Eliminator it might be a game changer for the A head limited rules platform.

68formalGT wrote:

Lem Evans wrote:

rmcomprandy wrote:What most people don't realize is that the "out of the box" A460 platform is over 30 years old.

Many places have improved and still can further improve this head in many different ways so, the simple A460 power comparison is just not viable to make.

Sure enough. The A460 heads have not had the evolution of the SCJ/P51/SR71 program.

Maybe not yet but if and when the new A460 head is finished from Eliminator it might be a game changer for the A head limited rules platform.

Not yet for sure.

How old are the C heads? When did they appear on the scene?

BBFTorino wrote:How old are the C heads? When did they appear on the scene?

I think the C-460 heads appeared in 1994. At least that's date on the 4 pages of instructions that came with the heads.
Charlie

c.evans wrote:

BBFTorino wrote:How old are the C heads? When did they appear on the scene?

I think the C-460 heads appeared in 1994.  At least that's date on the 4 pages of instructions that came with the heads.
Charlie

1994 is correct.