5 Petal or 7 Petal Reeds for High RPM on Merc Drag Motor

**CI STV** · 02-10-2022, 08:42 PM

I could watch those CNC cutting machines for hours. Amazing how much cheaper they make porting a cylinder head too (Elbow grease is expensive as hell these days). It blew me away that the GM CNC LS3 heads on my Vette only cost $640 apiece and yet flow over 360cfm. Not even Lee Sheppard coulda coaxed that out of an old SBC head.

As for the reeds: @Chaz : methinks you thinks too much…

It all makes sense though, even though my heads hurts now.
Make me know when you’re gonna do a set of compartmentalized 5 petals billet cages. I want mine with some extra fairy dust.

Hmmm, I could swear I’ve seen that picture with the 7 petal cage somewhere before…

The only problem with them is that he sells them with Boystomen dual flip-flappers as a kit. I suppose a man could cornswabble him into selling me the cages by themselves, though?
Looks like this reeds thing is like everything else: one man’s fruit is another man’s poison…

**Noah Burns** · 02-11-2022, 08:39 AM

I watch them for hours every day, trust me, you would grow weary of it quickly!

Originally Posted by CI STV

I could watch those CNC cutting machines for hours. Amazing how much cheaper they make porting a cylinder head too (Elbow grease is expensive as hell these days). It blew me away that the GM CNC LS3 heads on my Vette only cost $640 apiece and yet flow over 360cfm. Not even Lee Sheppard coulda coaxed that out of an old SBC head.

As for the reeds: @Chaz: methinks you thinks too much…

It all makes sense though, even though my heads hurts now.
Make me know when you’re gonna do a set of compartmentalized 5 petals billet cages. I want mine with some extra fairy dust.

Hmmm, I could swear I’ve seen that picture with the 7 petal cage somewhere before…

The only problem with them is that he sells them with Boystomen dual flip-flappers as a kit. I suppose a man could cornswabble him into selling me the cages by themselves, though?
Looks like this reeds thing is like everything else: one man’s fruit is another man’s poison…

**CI STV** · 02-11-2022, 08:57 AM

Originally Posted by Noah Burns

I watch them for hours every day, trust me, you would grow weary of it quickly!

LOL! “Familiarity breeds contempt”, as they say.

**patchesII** · 02-13-2022, 05:23 PM

I’ve ran both the Sportjet cages and 7 petal cages back to back on a 400+ hp 2.5 on a dyno. I didn’t find any difference between them. Made exactly the same power. What I did see the day was set of reeds cost us 15 hp

**CUDA** · 02-13-2022, 06:13 PM

Thick?

**patchesII** · 02-17-2022, 08:14 PM

Originally Posted by CUDA

Thick?

Yes. The bottom reed was too thick

**CI STV** · 02-25-2022, 06:59 AM

How thick is too thick? I noticed that PPE is now selling 1k weave carbon fiber reeds that are .017” thick for the 5-petal sport jet cages:
https://www.powerperformanceengineer...l-carbon-reeds
I know some people believe in CF reeds and others don’t, but I don’t have any personal experience with them.

**CI STV** · 09-30-2023, 08:15 AM

Resurrecting this old thread since a bought a set of the PPE carbon fiber reeds a while back, and I’m toying with the idea of changing the reeds I have in the motor now, which are what Diamond installed. Not sure what those are.

These are the reeds I’m talking about:

https://www.powerperformanceengineering.com/product-page/sportjet-5-petal-carbon-reeds

The description on PPE’s website is:

A complete set of Mercury Sportjet 5 petal carbon fiber reeds. These are single-stage 1k weave and .017'' thick.

Anyone have an experience with these or knows anyone that’s run these in a drag setup?
I’m just a bit worried since I’ve heard that the 5 petal aren’t as safe above 10K, as the
my boat turned ~10,400 in around ~800’ on the last outing, just before I nearly blew it over, lol.

**patchesII** · 10-02-2023, 07:43 PM

I’m sure the reeds are fine above 10000. When you start turning them 11000 and above you have to change reeds often, among other parts. I raced with guys that routinely turned engines 11300. He changed reeds every race day and went through cranks and rods like candy

**patchesII** · 10-02-2023, 07:46 PM

Back to the reed cages. We ran 7 petal cages, Sportjet cages and ported SJ cages all on a dyno back to to back. No change in power. I always ran 7 petals with Boyesen 267 reeds because I felt they gave the best throttle response

**CI STV** · 10-02-2023, 11:02 PM

Originally Posted by patchesII

I’m sure the reeds are fine above 10000. When you start turning them 11000 and above you have to change reeds often, among other parts. I raced with guys that routinely turned engines 11300. He changed reeds every race day and went through cranks and rods like candy

Thanks man. That’s very useful info.
Holy crap. Went through cranks and rods like candy you say? Yikes! I’m gonna try to keep the rpm below 10,500 and hopefully only running 800’ at a time won’t be so hard on parts.

**CI STV** · 10-02-2023, 11:03 PM

Originally Posted by patchesII

Back to the reed cages. We ran 7 petal cages, Sportjet cages and ported SJ cages all on a dyno back to to back. No change in power. I always ran 7 petals with Boyesen 267 reeds because I felt they gave the best throttle response

Thanks again. Also very good to know.

**Mrzip** · 10-04-2023, 07:41 PM

.. I like the 7

**patchesII** · 10-09-2023, 07:48 PM

Originally Posted by CI STV

Thanks man. That’s very useful info.
Holy crap. Went through cranks and rods like candy you say? Yikes! I’m gonna try to keep the rpm below 10,500 and hopefully only running 800’ at a time won’t be so hard on parts.

They’ll live a long time under 10600. I went into the Mercury A6 and added 2-3% of fuel to the bottom two cylinders above 9000 rpm. I highly recommend it if you have the ability

**CI STV** · 10-10-2023, 02:45 AM

Originally Posted by patchesII

They’ll live a long time under 10600. I went into the Mercury A6 and added 2-3% of fuel to the bottom two cylinders above 9000 rpm. I highly recommend it if you have the ability

Thanks Erik. Very much appreciated. Im gonna try to keep the RPMs below 10,500. I’m using what I believe is the A13 curve in my Brucato ACU.
As you can see, the fueling on the bottom cylinders is offset above 9000 on Group 2 (middle pair) and starts at 1% above 5000 and goes to 6% on Group 3 (bottom pair).
I’ve noticed that the offset on the A13 curve is larger than on the A6 curve. I suppose that’s because the A13 was for the slider manifold drag motors?
I think my tune is the same A13 tune Mercury that used on the stock slider Drag motors? See my tune below. I’ve also flowed my injectors and used the highest flowing ones in the bottom holes and the lesser flowing ones up top, which might mitigate the need for that much offset.
I have the Brucato software/cable, so I can make adjustments, but I haven’t done anything more than tweak the rev limit (now set at 11,000) and the offsets, which if memory serves, I’ve leaned out by 1% overall, ever since I flowed and reinstalled the injectors.
I’m also currently running the overall enrichment potentiometer set at 6% rich, but I intend to gradually tweak that downwards in 1 or 2% increments and carefully read the plugs and piston tops.