Kaase K1 cam vs. K2 cam in 521 with SR71 heads?

Anyone do a cam shootout between the K1 and K2 cam in a 521 with SR71 heads?
I just ran my 521 with SR71 heads on the dyno. It is 13:1 with flat top pistons and has the Trick Flow intake. Made 740 torque and 855 hp. Torque peak was 5600 rpm so I'm thinking the K2 cam would move things up a bit.

I'm out of room on the valve springs with the K1 cam so I can't go with more lift, but I can go with more duration. I have plenty of VP clearance with the K1 cam so I can put more duration in the engine. I just need to stay with 0.450 to 0.450 lobe lift. The K1 is 273/280 and the K2 is 280/288. I think the K2 uses the same lobe family as the K1, they just pick lobes further down the sheet.

If I can move the torque peak up to 6000 rpm I think the engine might get close to 900 hp.

What intake again? Work done to it?

What headers?

Are the heads out of the box or ported?

Your numbers are low iMO

Can you post up some dyno sheets and what specs for each pull?

Heads are out of the box, so is the intake. We tested both a 460 Victor and the Trick Flow R Series. The Trick Flow intake was 15 hp better so that is what is on the engine. Engine is 4.390 x 4.300 with 6.80 rods and flat top Mahle pistons. Compression is about 13.2 with a 0.040 head gasket. Headers are two inch dyno headers. Kaase told us the engine would make 850 hp and that is what it made so I think we're in the ballpark. I just feel that the cam is too small since the torque peak is only 5600 RPM. I think the carb, intake and headers can support more power.

I'll attach a couple of pictures

Headers are way too small too.

That should be making closer to 950 or you get everything right IMO

What’s it look like at the top of the rpm range? Is it falling off hard?

Andy, I don't know if you saw Glenn E.'s 552 SR71 Oem block 552 build and Dyno results?
If you did not I linked them below as they have a lot of good info on a SR71 build, even a 521-532, in my opinion.

https://www.429-460.com/t28926-dyno-tomorrow


https://www.429-460.com/t28929-dyno-overlay


Glen lists only partial cam spec's of 282 (I Ass/ume that is intake duration, he did not mention exhaust duration) .830" lift with a  (He was not positive on the LSA) 113 LSA with 2 degree's of advance.

He also had 14/1 compression due to the bigger bore and longer stroke.

It made 935HP 6,900Rpm and 769.8 ft/ibs at 5,800Rpm.

If it was my deal, for what you seem to be after, I think I would just step up to the K2 cam and a new spring pack/retainers ect.. Also a vacuum pump and 2 1/8" or larger headers, if you don't have them.

Question: Sounds like you have the K1 High Lift Cam with around .780" Lift vs the K1 Low Lift version with around .730" lift? Did you have the thread with the Maxxed out Manley Valve springs almost in Coil Bind with the High Lift K1 Camshaft on SR71's?

Thanks for the links, always interesting to see what similar combos make.
I've talked to a couple of cam guys and it seems like they agree that the K1 cam is making great torque down low, but if I want to shift the torque curve up a bit then I need some more duration. One told me that a 280/288 cam would probably make 900 hp at 7000 based on his simulation program.
The cam I have now is just labeled as K1. The cam card says 0.457 and 0.455 lobe lift for intake and exhaust. I don't recall anyone at Kaase asking me about a low lift or high lift cam. I told them that I was building a 521 with the SR71 heads and they recommended this cam. They did tell me that it should make 850 hp and it did.

Right now I'm trying to decide if I want to buy the K2 cam, or have a custom cam ground that uses a dedicated exhaust lobe. From what I can find out, the K2 cam uses Comp HXL lobes on both the intake and the exhaust. I'm sure it works okay, but if I'm going to buy a new cam then I might just spend a few extra bucks and get a custom cam ground that really meets my specs.

With that much compression and those heads you can probably use more split with a bit more separation.

With a 572 I have tested a few and 281/296 on a 113+2 worked very well but, did give up some torque below the higher torque peak which just did not matter. That cam had quite a bit more lift though ...(.493"/.476" lobe lift).

AndyF wrote:Thanks for the links, always interesting to see what similar combos make.
I've talked to a couple of cam guys and it seems like they agree that the K1 cam is making great torque down low, but if I want to shift the torque curve up a bit then I need some more duration. One told me that a 280/288 cam would probably make 900 hp at 7000 based on his simulation program.
The cam I have now is just labeled as K1. The cam card says 0.457 and 0.455 lobe lift for intake and exhaust. I don't recall anyone at Kaase asking me about a low lift or high lift cam. I told them that I was building a 521 with the SR71 heads and they recommended this cam. They did tell me that it should make 850 hp and it did.

Right now I'm trying to decide if I want to buy the K2 cam, or have a custom cam ground that uses a dedicated exhaust lobe. From what I can find out, the K2 cam uses Comp HXL lobes on both the intake and the exhaust. I'm sure it works okay, but if I'm going to buy a new cam then I might just spend a few extra bucks and get a custom cam ground that really meets my specs.

You're welcome. I am not sure on what lobes Kaase uses. With that said the CompCams HXL lobes between 272 and 288 degrees at .050" lift show to be .454" Lobe lift for all, though. They are on actual page 46 electric page 25 in the below link, and list at .772" lift with a 1.7 rocker arm ratio.

http://gatorperformance.com/catalog_lookup/comp_cams/Comp%20Cams%20Lobe.pdf

I am almost positive I talked to 5PointsSlow on his 510 Eddie Headed build and he checked his K1 cam card and said his was .730"ish lift even though he said .770"ish off the top of his head, in his dyno thread.

I was going to also recommend what Randy said about going to a little wider LSA to move the power band higher.

Went back and looked on 5Points deal, yea he listed his K1 spec.'s at the bottom of page 2 in the below link, towards the bottom of the page.

https://www.429-460.com/t29173p25-motor-is-going-on-dyno-next-week-want-to-guess-the-hp

Maybe that Manley High Lift SR71 spring thread will pop back up.

Here is the cam card for the K1 cam that Kaase sent me. This cam uses everything that the Manley springs have to offer. On paper the springs don't work with this cam and rocker combination but Kaase swore that it worked okay and it ran just fine on the dyno so Kaase wins that round. I stepped up to the T&D 1.750 rocker arms so my numbers might be a little different than what you would get with a stud mounted rocker arm.

This engine uses the Mahle Powerpack flat top pistons which have a 5.6 cc valve relief. Compression ratio is rated at 13.5 but works out to 13.2 in the engine since the pistons are 0.006 in the hole and we used a 0.040 Cometic head gasket.
Valve drop at TDC was 0.412 on the intake and 0.372 on the exhaust so lots of room. With the K1 cam installed at 107 we measured 0.155 VP on the intake at the closest point and 0.200 on the exhaust. So I have enough VP to go with more duration. I don't have enough valve spring capacity to go with more lobe lift.
From what I can glean so far the K2 cam will pick up power in this engine. I don't know if a different cam would pick up even more. I like the idea of a bit more split and using an exhaust lobe rather than two intake lobes, but that could be over thinking the issue.