RPM stays 7000 RPM regardless of Propeller pitch 24-29 Choppers or drags.

[PropmanIII]

I have a 93 260 that I tried to build to wind to at least 8000 rpm safely. I have it on an 1985 Varmint bass boat. I have run it to 92 mph (Handheld GPS). It seems to have strong acceleration and power. However, RPM stays at 7000 RPM regardless of Prop Pitch. 29 drag, 28 and 26 Choppers. tried a 24 pitch drag may that have got me maybe got another 200 RPM. Brucato ACU Rev limiter was supposed to be set at 8200 RPM. Engine has balanced and cut Small Rods and balanced Mahle pistons. Exhaust Chest is cut. Open Offshore exhaust. 150 Cylinder heads. Cant remember what exhaust tuner. Any suggestions as to why RPM'S at WOT will not go above 700 RPM ? (TACH maybe?) I haven't messed with the boat since I moved to Florida 7YRS ago but intend to figure this out when I get back to Kentucky. The boat handles the motor well and is a thrill to drive. I just want that last 1000 RPM if it is there. Thanx for any suggestions you may have.

[David - WI]

Somehow you have to verify the rev limiter setting and that the fuel table is filled in above 7k rpm. If it's just going pig-rich, full fuel above 7k it isn't going to pull to 8k rpm.

[skialot2]

Send your Brucato back to Brucato to have it checked out. I believe its only about $100.

[LakeFever]

I’ve been taking with some guys about how to turn serious rpm and was advised to get the brucato “unlimited” box. I’m going to try my chipped box one more time and if no bueno I’m getting one of those boxes to try

[tlwjkw]

The boat handles the motor well and is a thrill to drive. I just want that last 1000 RPM if it is there. Thanx for any suggestions you may have.

if ya can, make some video's (or at least some pictures) of it after ya get it straightened out!.. i ran one with my formula motor on it awhile back and was a total blast ta have around.. actually was more interesting at tha ramps when tha bass boat guys would gather 'round scrathin' their butts and askin' "jus what tha hell is that".. its a fishin' boat, can't ya tell!... it was jus straight up FUN ta drive.............

GL with it.... T

[LakeFever]

Strange thing to me is that’s the exact same speed my Vking hits the wall too. I’ve done 93 but most days 91/2 is it. I’m running a mildly ported FF laser injected 135psi motor with a chipped promax box 7600 limit.

[CI STV]

I have a 93 260 that I tried to build to wind to at least 8000 rpm safely. I have it on an 1985 Varmint bass boat. I have run it to 92 mph (Handheld GPS). It seems to have strong acceleration and power. However, RPM stays at 7000 RPM regardless of Prop Pitch. 29 drag, 28 and 26 Choppers. tried a 24 pitch drag may that have got me maybe got another 200 RPM. Brucato ACU Rev limiter was supposed to be set at 8200 RPM. Engine has balanced and cut Small Rods and balanced Mahle pistons. Exhaust Chest is cut. Open Offshore exhaust. 150 Cylinder heads. Cant remember what exhaust tuner. Any suggestions as to why RPM'S at WOT will not go above 700 RPM ? (TACH maybe?) I haven't messed with the boat since I moved to Florida 7YRS ago but intend to figure this out when I get back to Kentucky. The boat handles the motor well and is a thrill to drive. I just want that last 1000 RPM if it is there. Thanx for any suggestions you may have.

Could be the rev limiter is set lower than you think. You can either send the ACU back to Brucato to have them check and adjust the rev limiter if necessary, or buy the software and cable from Brucato and check and change it yourself.

A 260 isn’t supposed to be hitting a wall at 7000rpm, especially with a 24P drag prop. On my old mirage I could turn a 24P Yamaha 9400rpm in the 1/4 mile with my old stock 260 w/ 26cc heads.

Have you tried changing the reeds? Just a guess but if they’re weak and hanging open at high rpm that will act as a limiter, I would think?

[rjdubiel]

check the limiter first. Then do some testing as you could be rich right there and its just not going to pull more. I would also double check your compression as you may just not have the 150 psi that you think you should have. My 280 just does not pull more than about 8K on the Allison with my 28p river prop, runs 100-104 every time out, but just will not climb more with my current setup. Go lean or rich on the curve does nothing. Need more torque! With a 20P when drag racing it will go to 9K easy but try not to!