Setting up STV RR

[CI STV]

Just to update this thread, over the past few weekends I dropped the powerhead on and finished up the fuel system and the essential wiring and yesterday I managed to fire it up.

BTW: I wish I had used locktite instead of antiseize on the stud threads where they screw into the powerhead, because I tried to back one of the powerhead nuts off the stud and the frickin stud screwed out instead. I can’t see how I will get the damn powerhead off again without using a needle nose vise grip to gently clamp the end of the stud until I can screw the nut off enough to then clamp the stud behind the nut to screw it off the rest of the way, probably f@cking up the threads on the studs in the process.

Other than that, everything went together nicely and the engine fired right up. Ran it on the hose until it warmed up and blipped the throttle a few times. Sumbitch is very responsive and revs like a cordless drill too.

PPE hose kit is vey neat, IMV.

This is how I did the fuel system, for now, until I get a PPE fuel rail on it. The big black sensor on the bottom is the VDO fuel pressure sensor. I’ve mounted that with an adel clamp to secure it. Will do the same with the water pressure module, which you can barely see behind the wires coming off the FP sensor. Had to temporarily use a 5/16” bolt to block the nipple coming off the rail, since I didn’t have that some fuel hose and the adaptors to step up to the 3/8” (-6AN) hose that I used for the return.

Just need to finish connecting the sensor leads on the MXL2 dash and then I can move to wire the Digital Timer box.
Love how this dash looks. Can’t believe this thing has so many features built into one small dash. I’ll be able to log mph, rpm, trim position, engine height, water pressure, fuel pressure, EGTs, and with the CAN connection from the ACU (if I can get that to work), engine temp, IATs, etc.

[ShadowFlier]

Looking very nice and coming together well! PM me if your interested in a fuel rail, I just started making them.

[mach351]

Looking sweet

[CI STV]

Looking very nice and coming together well! PM me if your interested in a fuel rail, I just started making them.

Hey bro. That’s funny, because I was just on your site yesterday (and posted a link to your site in a boat racing group chat I’m on) and was saying to myself that I wished you did a fuel rail. I’m definitely interested in hearing more details about that. Will PM.

[Stoker boy]

Is there a big weight difference between hydraulic steering and cable/pulley steering. Also does cable/pulley have significant wheel torque? I love to paint my boat but I don’t want to add the weight.

Great looking boat!

[ShadowFlier]

Is there a big weight difference between hydraulic steering and cable/pulley steering. Also does cable/pulley have significant wheel torque? I love to paint my boat but I don’t want to add the weight.

Great looking boat!

String steering is the lightest steering system out of all of them. It also gives you complete feedback as to what the boat is doing which is important during drag racing. You will feel the prop torque the wheel a little but if it is set up correctly it is not much.

[RBT]

Unless you get creative it isn’t lighter

[Stoker boy]

Thanks for the replies. I guess I’ll stay with what I have.

[CI STV]

For a purpose built O/B drag setup like this, I prefer the cable/pulley setup over hydraulic steering because, as Shadowflier said, it gives you better feedback.
I had hydraulic steering in my previous boat (American Offshore 2600) as that was what was necessary with a stern drive. Before that, I had a lightweight (475lb) Mirage River Racer with both a nitroused OMC and then a Merc Drag/12” setup, and I loved how the cable/pulley steering worked with both of those setups.
So, although a lot of people told me to throw a hydraulic system in it, I decided to use the cable/pulley steering, as the boat was setup with that before anyhow, although I replaced just about everything now except the cable and helm.
Thanks to Ox Performance, I was able to do that.

[Stoker boy]

I had a 20 foot hull with duel opposed steering cable (not pulley) 20 inch mid moderate wheel torque but you needed to feel the boat to drive it properly. When I acquired my heavy Mirage Jaguar, heavy by today’s standards 480 lbs. I used the same motor/steering configuration the wheel torque was too much. Maybe because I’m old man now. I set the boat up with a 12 inch mid and hydraulic steering I have no problem driving the boat seems to drive itself.

Even with a modified 260 sometimes on nitrous. I was thinking more of weight saving but if it’s not that great a difference no sense going through the hassle.

[CI STV]

Haven’t updated this old build thread in a while. Been making slow but steady progress and have just about all the major work done. Just need to install the windshield and the lower unit, which I need to cut a recess for the shift lever to come out the side, and do some epoxy to repair a bubble on the side. Then I should be able to test this thing.

Installed an Ox Performance fuel rail. Very neat piece.

Got AiM MLX2 dashlogger set up and working as well as the Digital Trim timer box. I’m running the up trim through a PPE trim limit switch, which has an AiM potentiometer on it to tell me trim position on the dash (on a different screen from the one shown). I also have the PPE up/down trim sensor which also displayed in the dash as well. That’s also controlled by the timer, which I need to dial in during testing. The trim buttons on the wheel are wired independently, so that I can trim and jack the motor manually as well.

Got all the rubrail reinstalled, including a new corner piece on the starboard stern, which was missing. That was a b!tch to get done, but turned out nice enough.

[mach351]

Looks mean

[CI STV]

I’ve got the boat finished, but didn’t get a chance to test it because we had two storms pass by (Grace and Ida) so I had to focus on battening down, and I’m now traveling, so I won’t get to test it until the end of the month.
Here are some more recent photos:

Attachment 492659

[Stoker boy]

Looks Great!!!!

[CI STV]

Just wanted to update this thread, so that it can be used for future reference, since I realised that I hadn’t posted on here since I got the boat going.

I’m still trying to dial in the prop shaft height, and I believe I need to bring it up more, since I’m seeing ~6.75% on my last outing with it at 1/2 - 5/8” above the pad. I’ve also not run any more than 1* of positive trim, with most runs around neutral. I’ve been trying to get engine data and dial in the fuel curve, since it was running rich, even after I installed the 17cc chambers in the PPE heads.

Here’s a screen shot of the data from close to the end of a pass I made the other day. This is with a Ronnie Gilbert 20P; 1.78 gear; engine height at ~ 1/2” + (13mm on the data logger); trim @ 33mm (35mm is +1*).

Here’s what I’ve calculated for prop slip, using an online calculator:

I’m thinking, how this make sense, unless the prop is too deep? I typically just set the engine height and I currently don’t have that pump hooked to the trim timer. I have the trim on the timer, but on that pass I forgot to hit “Enter” so I had to trim it out manually, and only managed to get it to 33 mm instead of 35mm, which is +1 degree. The boat planes very quickly, but it feels like it’s loading up and running a bit flat. I know STV run fast and flat, but I’m thinking there’s some more on the table.

Here’s a link to a video of a run that same day, albeit not that exact run that the data above relates to:

https://www.youtube.com/watch?v=FwK57GvviKk