Re: Jon Kaase SR71 Cylinder Heads

cletus66 March 9th 2019, 9:58 pm

BBFTorino wrote:Man, if you're going with a big Roots type blower, I'd use the Boss heads!!

I remember reading that the SOHC FE heads worked great with a blower till the bottom end fell apart, and the Boss heads didn't work well with a blower due to the port design. I read too much when I drink... scratch

SandHillsHillbilly March 9th 2019, 10:11 pm

738drvr wrote:You’re building a street engine. Either set of heads would be more than enough for what you’re doing. I would use carbs for that build. Mechanical injection is really best at the track not the street.

I will second that. I build blown mech injected systems all day long. You will hate driving it on the street. If you are wanting the nostalgic look you can still use the mech. pump and injector hat, just convert it to EFI. You will appreciate it especially when it comes to drag week.

jasonf March 9th 2019, 11:09 pm

Ol'Blue77 wrote:Question 1:
What makes the Kaase Boss 9 Heads "not a race head"? Valves, fluid flow, head material?
Question 2:
What makes the SR-71 more of a race head?
Question 3:
I know that flat top and dome pistons need the valve reliefs for the Boss 9 heads, but do 38cc dish pistons need valve reliefs? I can't find Diamond or Mahle dish pistons that say they work with the Boss 9 heads.
Question 4:
Do the SR-71 heads have enough of a valve angle on them that the piston would need valve reliefs?
Story:
I am planning to build a 545 stroker, Hampton 8-71, Hilborn mechanical injection and stuffing this into a 65 Galaxie. About a year ago, I was dead set on the Boss 9's but now these SR-71's are out, and I am stuck between the two. I want the 38cc pistons so that I will have 8.5:1 compression and with the Hampton running 6-8 pounds, that will give around 12:1-13:1.
This is for a drag race build, in hopes to compete at Drag Week. Not necessarily to win but at least finish and average in the 9's or 10's.

Either head should get you to that goal without a 671..

Carbguy March 13th 2019, 5:32 pm

Ol'Blue77 wrote:Question 1:
What makes the Kaase Boss 9 Heads "not a race head"? Valves, fluid flow, head material?
Question 2:
What makes the SR-71 more of a race head?
Question 3:
I know that flat top and dome pistons need the valve reliefs for the Boss 9 heads, but do 38cc dish pistons need valve reliefs? I can't find Diamond or Mahle dish pistons that say they work with the Boss 9 heads.
Question 4:
Do the SR-71 heads have enough of a valve angle on them that the piston would need valve reliefs?
Story:
I am planning to build a 545 stroker, Hampton 8-71, Hilborn mechanical injection and stuffing this into a 65 Galaxie. About a year ago, I was dead set on the Boss 9's but now these SR-71's are out, and I am stuck between the two. I want the 38cc pistons so that I will have 8.5:1 compression and with the Hampton running 6-8 pounds, that will give around 12:1-13:1.
This is for a drag race build, in hopes to compete at Drag Week. Not necessarily to win but at least finish and average in the 9's or 10's.

1/2: Neither the Boss Head or the SR-71 are race heads they are designed to work within specific parameters. The Boss is designed to fit the original Boss architecture as far as Valve Covers, Intakes, and Exhaust to reproduce a specific look for heads that are no longer manufactured. The SR-71 while having phenomenal performance potential is not an all out race head as it was designed and engineered to work with factory CJ style intake and exhausts. If you were to build a true race head without considering some of these things there are always more things you can do.

3: Since the combustion chambers are different sizes between these two cylinder heads you compression ratio would vary. Both Diamond and Mahle offer shelf pistons for the Boss Heads but they are obviously different between a Boss and SR-71.

4: Yes you would need valve reliefs in your pistons to run an SR-71 head.

Either head would get you in the power range that you are wanting, it would just be a matter of matching up the rest of the proper parts and pieces and what look you are wanting. If you're wanting the Shotgun look then go Boss if not the SR-71 is an easy choice.

738drvr March 13th 2019, 5:44 pm

BINGO^^^^^^^

Ol'Blue77 March 20th 2019, 9:02 am

So what I'm getting at it is, use EFI, diamond will custom make the pistons i need, and the power numbers between the heads are so similar the only difference is the number of $$$'s. And the cool look.

738drvr March 20th 2019, 3:18 pm

You cracked the code. You got it.

Now build it.

738drvr March 29th 2019, 1:22 am

Sent a head to RaceTec today. Should have my pistons started next week. Ordered the cam from Bullet today.

Car is being finished this week(wiring).

Back to the chassis guy in a week or two to set the block back on the motor mounts.

Once the engine is done, I think I’m going to let Elston do the 421 headers on it.

We’re going to be on kill for Dragweek this year. Hope to be a solid second. First if Doc doesn’t show or breaks in Pro Street NA. He’s good(and fast and way bigger than us 706 vs 557).

CDMBill May 20th 2019, 1:19 pm

Carbguy wrote:
Ol'Blue77 wrote:Question 1:
What makes the Kaase Boss 9 Heads "not a race head"? Valves, fluid flow, head material?
Question 2:
What makes the SR-71 more of a race head?
Question 3:
I know that flat top and dome pistons need the valve reliefs for the Boss 9 heads, but do 38cc dish pistons need valve reliefs? I can't find Diamond or Mahle dish pistons that say they work with the Boss 9 heads.
Question 4:
Do the SR-71 heads have enough of a valve angle on them that the piston would need valve reliefs?
Story:
I am planning to build a 545 stroker, Hampton 8-71, Hilborn mechanical injection and stuffing this into a 65 Galaxie. About a year ago, I was dead set on the Boss 9's but now these SR-71's are out, and I am stuck between the two. I want the 38cc pistons so that I will have 8.5:1 compression and with the Hampton running 6-8 pounds, that will give around 12:1-13:1.
This is for a drag race build, in hopes to compete at Drag Week. Not necessarily to win but at least finish and average in the 9's or 10's.

1/2: Neither the Boss Head or the SR-71 are race heads they are designed to work within specific parameters. The Boss is designed to fit the original Boss architecture as far as Valve Covers, Intakes, and Exhaust to reproduce a specific look for heads that are no longer manufactured. The SR-71 while having phenomenal performance potential is not an all out race head as it was designed and engineered to work with factory CJ style intake and exhausts. If you were to build a true race head without considering some of these things there are always more things you can do.

3: Since the combustion chambers are different sizes between these two cylinder heads you compression ratio would vary. Both Diamond and Mahle offer shelf pistons for the Boss Heads but they are obviously different between a Boss and SR-71.

4: Yes you would need valve reliefs in your pistons to run an SR-71 head.

Either head would get you in the power range that you are wanting, it would just be a matter of matching up the rest of the proper parts and pieces and what look you are wanting. If you're wanting the Shotgun look then go Boss if not the SR-71 is an easy choice.

You don't need a blower on a 545" with either head to go high 9's low 10's at Drag Week with that Galaxie. It would be way cool with a blower sticking through the hood. What fuel do you plan to run? That decision will influence everything else. If it were me I'd up the compression, run well under driven on the road with pump premium of E85 depending on year and route.Then over drive it and run C16 at the track. If you go stand alone EFI you'll thank me later.

427John June 3rd 2019, 10:41 am

This may be old news but just saw an episode of engine power I had DVR'ed about JKRE and the SR-71 in particular,they built a 598 with what appeared to be out of the box SR-71's and made 1011hp NA,it also had a sidebar with JK explaining the design with a cut up head for visual aids.Pat T. refers to the heads as ported as cast.At the beginning during the walk around they have some good shots of that bitchin 900 horse Mel motor that won EMC vintage.Head gasket?Thats some creative interpretation there.

Dave De August 12th 2019, 11:37 am

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.

Comparison update... track ET only
My 580, E85 package coming from worked over P-51's that had been moderately ported to the SR-71's out of the box without even taking the casting fuzz out of the bowls. I even used my PAC springs from the P-51's. The engine was identical except for the Diamond pistons/rings were replaced with .005" larger bore. There were no other changes to the car right down to the MT 31x13 slicks that were old for both tests. They are so bad that I think I'm going to pickup 7/100ths with going back to 32x14's.

Milan Dragway similar DA air days from 2300 to 2800 ft throughout the day
P-51's ran 9.11-9.14 ET 1/4 mile, 2018 data
SR-71's ran 9.04-9.07 with an extra 1.5 mph trap speed. 8/11/19 data

I'm sorry to take so long to get this info up to you. I moved and had to put racing on hold. This is not intended to be a super precise comparison but just data from a budget bracket racer. I think the 71's are great and will see the potential as I have the heads ported in future years.

For others that are using smaller cylinder bores up to 4.440 stay with SCJ's or P-51's because its not worth the piston expense for the valve reliefs.
An extra SR-71 benefit for large cube motors that have fuel distribution issues at the corners where they are much leaner with the Victor manifold appears to have a better spark plug read with the inner holes. I dont see a difference between the outside and the inside for a rich/lean variance. This must be from the SR-71's raised intake ports ability to crutch the poor port flow distribution from the Victor.

Lem Evans August 12th 2019, 7:01 pm

"For others that are using smaller cylinder bores up to 4.440 stay with SCJ's or P-51's because its not worth the piston expense for the valve reliefs."

That and if you have a bore less than 4.500" you'll get a smaller exhaust valve.

wayney August 12th 2019, 8:59 pm

Dave De wrote:
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.

Comparison update... track ET only
My 580, E85 package coming from worked over P-51's that had been moderately ported to the SR-71's out of the box without even taking the casting fuzz out of the bowls. I even used my PAC springs from the P-51's. The engine was identical except for the Diamond pistons/rings were replaced with .005" larger bore. There were no other changes to the car right down to the MT 31x13 slicks that were old for both tests. They are so bad that I think I'm going to pickup 7/100ths with going back to 32x14's.

Milan Dragway similar DA air days from 2300 to 2800 ft throughout the day
P-51's ran 9.11-9.14 ET 1/4 mile, 2018 data
SR-71's ran 9.04-9.07 with an extra 1.5 mph trap speed. 8/11/19 data

I'm sorry to take so long to get this info up to you. I moved and had to put racing on hold. This is not intended to be a super precise comparison but just data from a budget bracket racer. I think the 71's are great and will see the potential as I have the heads ported in future years.

For others that are using smaller cylinder bores up to 4.440 stay with SCJ's or P-51's because its not worth the piston expense for the valve reliefs.
An extra SR-71 benefit for large cube motors that have fuel distribution issues at the corners where they are much leaner with the Victor manifold appears to have a better spark plug read with the inner holes. I dont see a difference between the outside and the inside for a rich/lean variance. This must be from the SR-71's raised intake ports ability to crutch the poor port flow distribution from the Victor.

how heavy is the car? cr?

738drvr August 13th 2019, 5:33 pm

Dave, tell us the weight of your car and your trap speed.

The folks at Kaase’ told me that the smaller exhaust valve on a smaller bore doesn’t affect power. They believe that is due to unshrouding the valve.

Hope to run mine next week.

738drvr August 13th 2019, 7:46 pm

Lem Evans wrote:"For others that are using smaller cylinder bores up to 4.440 stay with SCJ's or P-51's because its not worth the piston expense for the valve reliefs."

That and if you have a bore less than 4.500" you'll get a smaller exhaust valve.

I would disagree that it’s not worth it. You can easily sell P-51’s and the difference between the two from 6,000-7,500 is noticeable. Kaase notched the pistons himself and depending on cam timing and PTV clearance, you may not even need to notch. The SR-71 is clearly a better head than the P-51.

P-51: avg. 858hp 671 trq
SR-71: avg. 904hp 707 trq

This is on Jon’s 521 dyno mule. Results from page 4 of this thread.

Lem Evans August 13th 2019, 8:11 pm

738drvr wrote:
Lem Evans wrote:"For others that are using smaller cylinder bores up to 4.440 stay with SCJ's or P-51's because its not worth the piston expense for the valve reliefs."

That and if you have a bore less than 4.500" you'll get a smaller exhaust valve.

I would disagree that it’s not worth it. You can easily sell P-51’s and the difference between the two from 6,000-7,500 is noticeable. Kaase notched the pistons himself and depending on cam timing and PTV clearance, you may not even need to notch. The SR-71 is clearly a better head than the P-51.

P-51: avg. 858hp 671 trq
SR-71: avg. 904hp 707 trq

This is on Jon’s 521 dyno mule. Results from page 4 of this thread.

If there is no advantage to the 1.76" exh. valve looks like they'd make it simple and only offer one size exh. valve....strange.

738drvr August 13th 2019, 9:54 pm

Cliff’s exact words were “no real difference on the flow bench or the dyno”.

His words not mine.

rmcomprandy August 14th 2019, 12:04 am

738drvr wrote:Cliff’s exact words were “no real difference on the flow bench or the dyno”.

His words not mine.

Not until they are fully ported on the exhaust side ... then there IS a difference.

Lem Evans August 14th 2019, 10:06 am

738drvr wrote:Cliff’s exact words were “no real difference on the flow bench or the dyno”.

His words not mine.

I didn't say he didn't say it...........I'd heard it before.

738drvr August 14th 2019, 11:31 am

Lem, I get your point.

My point is the SR-71 is the best CJ head period.

I was going to buy Boss 9 heads for my build but this saved me money on an intake, headers, etc... and will make the same power as the Boss 9 stuff.

I’m thankful for what Kaase has done for our community.

We are indebted to him for his hard work and commitment to the BBF.

Lem Evans August 14th 2019, 8:48 pm

738drvr wrote:Lem, I get your point.

My point is the SR-71 is the best CJ head period.

I was going to buy Boss 9 heads for my build but this saved me money on an intake, headers, etc... and will make the same power as the Boss 9 stuff.

I’m thankful for what Kaase has done for our community.

We are indebted to him for his hard work and commitment to the BBF.

Actually it's the ultimate cylinder head. In some applications the SCJ with back cut intake valves is the best head.

Dave De August 15th 2019, 10:24 am

wayney wrote:
Dave De wrote:
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.

Comparison update... track ET only
My 580, E85 package coming from worked over P-51's that had been moderately ported to the SR-71's out of the box without even taking the casting fuzz out of the bowls. I even used my PAC springs from the P-51's. The engine was identical except for the Diamond pistons/rings were replaced with .005" larger bore. There were no other changes to the car right down to the MT 31x13 slicks that were old for both tests. They are so bad that I think I'm going to pickup 7/100ths with going back to 32x14's.

Milan Dragway similar DA air days from 2300 to 2800 ft throughout the day
P-51's ran 9.11-9.14 ET 1/4 mile, 2018 data
SR-71's ran 9.04-9.07 with an extra 1.5 mph trap speed. 8/11/19 data

I'm sorry to take so long to get this info up to you. I moved and had to put racing on hold. This is not intended to be a super precise comparison but just data from a budget bracket racer. I think the 71's are great and will see the potential as I have the heads ported in future years.

For others that are using smaller cylinder bores up to 4.440 stay with SCJ's or P-51's because its not worth the piston expense for the valve reliefs.
An extra SR-71 benefit for large cube motors that have fuel distribution issues at the corners where they are much leaner with the Victor manifold appears to have a better spark plug read with the inner holes. I dont see a difference between the outside and the inside for a rich/lean variance. This must be from the SR-71's raised intake ports ability to crutch the poor port flow distribution from the Victor.

how heavy is the car? cr?

Car and me in it is 3250.
Compression ratio is 13.6 to one.

Dave De August 15th 2019, 10:30 am

738drvr wrote:Dave, tell us the weight of your car and your trap speed.

The folks at Kaase’ told me that the smaller exhaust valve on a smaller bore doesn’t affect power. They believe that is due to unshrouding the valve.

Hope to run mine next week.

Car and me in it is 3250.
Trap speed is 148 to 149 with the old MT 31 tall slicks. Most of the gains to this car have come from improved 1/8th mile numbers where the car goes 5.70 to 5.76 @ 119.5 mph. Its been hard to get this car to improve the back half of the track.

Lem Evans August 15th 2019, 11:55 am

So, the engine still has a Victor intake?

Dave De August 15th 2019, 9:42 pm

Lem Evans wrote:So, the engine still has a Victor intake?

Yes it does I found that the TFS was too tall for the raised SR71 heads on my car which limited the induction opening with the hood.

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