sgx 21 , what next ?more speed req.

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Tofastformellow

Well-Known Member
Joined
Apr 15, 2005
Messages
387
Gday , i have a sgx 21 , for some reason its got sgx-1 on the side of it , but i think its just an sgx.

i am pretty happy with it.

after the mac 21 wore out i went to a green head valv, and have been running it on 60% with an 'AB' h7.

its ok, but it runs really flat .. i have scuffed up the bottom of the sponsons. clean and sharp.

i want more speed.

where do i go from here ?,

if i add pitch with like a v945 rounded it just clamps the front end down and the motor wont launch it with its low front end geometry..

i need a prop with heaps of pitch but NO lift is suppose.

if i shorten the pipe it wont get up at all. from 215 mm . a good freind suggested getting the pipe down to around 165-170 mm but it wont run or pipe at all on that setting no matter how lean i get the needle ...

i have tried playing with the limited AOA that the boat has , and have lifted the front end a little , but now if it hits a little ripple it pulls the front LH sponson under and down she goes. ie to loose.

wet weight is around 1.7 kgs , or 3.74 pounds and i run on fresh water at sea level.

any suggestions ?

many thanks

Jason
 
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Jason,

Better pipe and less propeller. Try a 1445 @ 3.33" of cup and try a pipe at 7 1/2".

Less is more. You have too much propeller on your boat and too long of pipe to go

faster. What pipe are you running? Richen up with the shorter pipe length.

Thanks,

Mark Sholund
 
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Jason,

Listen to Mark, I have similar set up, but my boat is a SG, I also run the green head Valvola with an Andy Brown fat pipe at 7.5 inches long from the center side of the case to the weld of the pipe. Im running a 1445 with a 4.1 cup from Mark and all I can tell you is that my boat moves.... Try changing the prop first, then add a couple of 440 washer to the front left boom and three 440 washers to the right front boom (turn fin side). I run 1/2 deg neg on the strut with the prop about 1/8inch higher from the bottom of the transom.

Check out my boat running at the 2007 Namba nationals.

a_hydro.jpg
 
How much head clearence do you have? And yes, what pipe?

If the H-7 is cut down to 46 mm there is nothing faster for oval racing. We have run 82 mph with the H-7. We only run the 1445 when we are looking to be a little more conservative.

You will just need to extract a little more power from the engine.

How much oil is in your fuel?
 
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How much head clearence do you have? And yes, what pipe?
If the H-7 is cut down to 46 mm there is nothing faster for oval racing. We have run 82 mph with the H-7. We only run the 1445 when we are looking to be a little more conservative.

You will just need to extract a little more power from the engine.

How much oil is in your fuel?

The head clearance is stock , can i pull a shim or would it need machining , it is an AB H7 at 46 mm,

82 mph wow that would be a dream... LOL's i am getting more around 62 mph ... :lol:

i am running a Spp ms21 pipe, what would be the best AB pipe on the motor in that hull with that prop....?

finding a good SH AB pipe that works for sale in oz is a little hard to find.

Sigh , i run 18% oil in there 9% of each ... should i run less and can it still be reliable? i dont run it silly lean or anything like that ..

Lorenzo , your boat running looks much like my SG45 in attitude. the front sposons on this 21 have much less attack but UP at 80 mph it wouldnt need much lift !!!...

it dosent like a negative strut at all..?? :huh: it runs best neutral...?

Thanks guys as always

Jason
 
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Definately too much prop for that pipe and setup Jase. The SPP MS21 likes the 1445 and pulling a lot of rpm. It's not a torque pipe, even on a Nova. I couldn't pull a H7 with that pipe to any useful speed, just not enough rpm. With a 1445 though it pulled fantastic rpm.
 
hi tim , im not a huge fan of the ms21 , i much prefer the td21 , its got herbs

i used to pull a v945 on my FF21 with the same engine and a TD 21 pipe. !! i might have seen an honest 70 with that setup , raspy rich

not an ideal race setup , but if you could get clean water it stayed hooked up and squeeled.

going to the sgx and loosing 500 grams of boat weight and i have lost 8 mph ! and the ability to launch the big props in my box.

i suppose thats the difference between high lift and low lift boats...

its got me scratching my head ..

i have some of marks old 1445's to try .they havent impressed me much yet ....but i havent tried a real short pipe on the 1445s either ...

i am waiting to get the boat back in the water as its gotta go better than it has..

jason
 
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SG's and SGX's run more weight % on the strut than the FF. Requires a different set-up for sure!

Try the MS with a 1445 with little to no extra cup and get that engine pulling big RPM. Should get you close to the numbers you are after.

Mark S has mentioned he's got very good results with that combination to me before. Aaron has used that combination too. Those engines love to rpm - why not take advantage of it!
 
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Jason,

Measure your head. You want to be at .007" - .008"

If you have the newest CMB Valvola, they made the bypass ports too big which hurt the torque.

Your only option is to go for RPM as Tim suggested.

With 60/18 fuel, dont expect more than about 68 mph for a good heat race set-up,

Which btw will win a lot of races.

We run 70/12 in our 21, but you have to go with what you can get.

I'm working on a new 21 pipe. It is similar to the AB 21 FAT pipe, but will have a little more top end and overall more power.
 
Jase,

that is my old boat you are running, with my mac21 and td21 pipe and that h7

i was running 70mph on the gun.

if you want to run the ms pipe, like Tim and Mark said.... 1445 with about 3.3 of cup and real short pipe

and let it rev to the moon....i have run this set up as well, with real good results..

as Andy said if your running high 60's in race trim you will win alot of races...

i can tell you that there are only a couple of 21 riggers in OZ that are running 70mph in race trim...

run a shorter pipe,...... ;)

around 7-1\4 to 7-1\2, dont forget 21 engines are built to rev...

i see alot of people go the wrong way about it.... i no some guy's that are running the same

cup in there 21 rigger props as i run on my 45 rigger,

regards Aaron
 
Jase,

Are you restricting your water at all? Makes a huge difference with 21's.

Also carbon pipes need to come up to temp so you need to allow for it with your mixture and testing process.

Yep - high 60's are fast enough on a boat that is set up well. I won more races back when I was slower than what I do now with a faster set-up. **** frustrating really. I haven't won a sanctioned event in 3.5 hydro for a few years now. Even with "conservative" set-ups, stuff still happens during races.
 
thanks guys as always

i have some stuff to try now.

aaron can you do the head clearance ?, i have no idea how to get such am accurate close clearance on such a small engine ..

Jason
 
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We did not attend this years IMPBA Internats, but I was just cheking the SAW results of the 21 hydros.

1st place ran 71 mph

2nd place ran 61 mph

3rd place ran 59 mph
 
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Andy,

If I remember correctly,you won the Worlds with a 1445 @3.33" of cup?

The 1445 and the H-4 and H-5 are working very well for many racers

around the world. Jason have you lighten up your drum rotor yet?

Thanks For The Information Andy,

Mark Sholund

Props-4-U
 
Andy,
If I remember correctly,you won the Worlds with a 1445 @3.33" of cup?

The 1445 and the H-4 and H-5 are working very well for many racers

around the world. Jason have you lighten up your drum rotor yet?

Thanks For The Information Andy,

Mark Sholund

Props-4-U

That is correct Mark.

Racing at the Worlds is different than here in the USA. Drivers are very consistant. They run eight boat heats and they almost always all finish. There is a lot of traffic on the coarse so throttling is very important.

That is why I used my conservative choice of propellor.

It took me a a little bit to adjust my driving style. You don't just go out and hammer down. I learned that reak quick.

I have a photo of a worlds 15 cc hydro final start. It was 8 boats all coming for the start in a tight pack. The heat was 7 laps and all but one boat finished. VERY INTENSE!

I was glad they use transponders for lap counting and timing.
 
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Andy,
If I remember correctly,you won the Worlds with a 1445 @3.33" of cup?

The 1445 and the H-4 and H-5 are working very well for many racers

around the world. Jason have you lighten up your drum rotor yet?

Thanks For The Information Andy,

Mark Sholund

Props-4-U

That is correct Mark.

Racing at the Worlds is different than here in the USA. Drivers are very consistant. They run eight boat heats and they almost always all finish. There is a lot of traffic on the coarse so throttling is very important.

That is why I used my conservative choice of propellor.

It took me a a little bit to adjust my driving style. You don't just go out and hammer down. I learned that reak quick.

I have a photo of a worlds 15 cc hydro final start. It was 8 boats all coming for the start in a tight pack. The heat was 7 laps and all but one boat finished. VERY INTENSE!

I was glad they use transponders for lap counting and timing.
I would LOVE to see the photo - is it on your website or can you post it here? I love INTENSE!
 
Andy,
If I remember correctly,you won the Worlds with a 1445 @3.33" of cup?

The 1445 and the H-4 and H-5 are working very well for many racers

around the world. Jason have you lighten up your drum rotor yet?

Thanks For The Information Andy,

Mark Sholund

Props-4-U

That is correct Mark.

Racing at the Worlds is different than here in the USA. Drivers are very consistant. They run eight boat heats and they almost always all finish. There is a lot of traffic on the coarse so throttling is very important.

That is why I used my conservative choice of propellor.

It took me a a little bit to adjust my driving style. You don't just go out and hammer down. I learned that reak quick.

I have a photo of a worlds 15 cc hydro final start. It was 8 boats all coming for the start in a tight pack. The heat was 7 laps and all but one boat finished. VERY INTENSE!

I was glad they use transponders for lap counting and timing.
I would LOVE to see the photo - is it on your website or can you post it here? I love INTENSE!

Yes, go to the Gallery page and click on 2002 World Champs. The pic is on the bottom row.

Eight boats are coming for the strart. Six are on the front row and two are in the back row hidden by roostertails.
 
OK so i shortened the pipe up to 7 then 7 1/4 and gave it a run with 1445 , a h4 and the h7

the 1445 and the h4 certinally got the rpm UP ! , but the water speed was always UP with the h7

it went out and screamed for 3 laps then went of the pipe.

the gallary behind me were all telling me to stretch my pipe out , LOL's i was trying to test the short pipe scenario !!

anyhow i richened the needle up 1/16th then another 1/16th and it didnt make much difference , it would scream for three laps then fall of the pipe and crawl back to the landing area. the motor did sound alot raspy'er thou with a short pipe

so didnt i richen it enough ??

will it need what a 1/4 turn out or half a turn out >?

i satifsfied the gallary , lengthened the pipe to 7 1/2 and left the h7 on it and it went ok , same as before ...but would do a full race if needed

i want it to run a just a little faster, the motors probably done 2 gallons now , but the bearings are smooth and its still got its nip at the top ..

How do i lighten up the drum rotor , sounds like i would need a lathe for that ... -_-

thanks

Jason
 
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OK so i shortened the pipe up to 7 then 7 1/4 and gave it a run with 1445 , a h4 and the h7 the 1445 and the h4 certinally got the rpm UP ! , but the water speed was always UP with the h7

it went out and screamed for 3 laps then went of the pipe.

the gallary behind me were all telling me to stretch my pipe out , LOL's i was trying to test the short pipe scenario !!

anyhow i richened the needle up 1/16th then another 1 1/16th and it didnt make much difference , it would scream for three laps then fall of the pipe and crawl back to the landing area. the motor did sound alot raspy'er thou with a short pipe

so didnt i richen it enough ??

will it need what a 1/4 turn out or half a turn out >?

i satifsfied the gallary , lengthened the pipe to 7 1/2 and left the h7 on it and it went ok , same as before ...but would do a full race if needed

i want it to run a just a little faster, the motors probably done 2 gallons now , but the bearings are smooth and its still got its nip at the top ..

How do i lighten up the drum rotor , sounds like i would need a lathe for that ... -_-

thanks

Jason
Jason,

Try to run the 1445 with the pipe at 7 1/2 but go very rich then lean it down little bit at a time. You will get it to run allot better than the H7. Is your H7 stock or has it been cut back? If it is stock, then that;s way too much prop... I run the SG with a Valvola green head (same as the Mac 21) and I run the Andy's fat pipe at 7 1/2 on a good day (cool day) and 7 7/8 on a hot day. i run a 1445 with 4.09 cup and my boat screams. My engine has two racing seasons on it and I can still run same set up as when new. Mac engine is an excellent engine, just let rev.... One you find your needle using the 1445, then you can try cupping it up until you find that speed you're looking for.... I'm new to this class and I've already won the 2007 Namba Nationals and got fast time at the Nationals and just won my district championship using the set up I just mentioned. Take it for what is worth, at the end of your day, it is you that makes the decision to what advice you want to follow....

Lorenzo
 
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