19' Spectra Twin Turbo

[Maw]

A little late, but I figured I'd open a thread on the 19' Spectra jet project we're doing.

We bought it for the middle son a couple of years back, pocket change purchase, "just get it out of my yard" kind of deal. It was found half buried in a compost pit, tires rotted out and sitting on the rusted rims, the back half including most of the engine hidden from view under rotting garbage and leaves. Bought new rims and tires then dragged it back to the shop.

After a thorough cleaning that filled a dumpster we began tearing into what we had bought.

The original 454 BBC had long since filled with water and rusted together solidly. It was a cast crank 2 bolt main so no big loss there. The heads "were" nice '71 vintage oval ports but upon magging they showed spiderweb cracks in every chamber.

We found a 4 bolt bare block on Craigslist, a new steel Chevy crank on ebay, then rods and forged pistons from Summit. Compression was selected at 8.7:1. A pair of Summit rectangular port assembled heads were purchsed. These are actually Dart Iron Eagles with the Dart logo machined off on the outside, but left in place on the inside. They come with Comp Cams springs and SS Manley valve. Very good deal for $1,100. The cam is a Comp Cams flat tappet hydraulic XE with "moderate" lift and duration specs and a 113* LSA. We didn't know if this was to remain a NA motor or get a little boost at some time. We tried to give ourselves the flexibility during the build.

We found a complete PFM kit on Craigslist for $700. It included everything needed for both a blow-thru and draw-thru installation and came with the large intercooler.

The block is now setting in the boat for initial fittment. We've added the PFM kit and have decided to go with a blow-thru EFI system.

Matt wants the exhaust to show so we waterjetted a few flanges out of 3/8" thick #304 stainless, then bought 90* and 45* #304 elbows, 1/8" wall from McMaster-Carr. We finished those off last night, they now need to be sanded and polished but that will wait until all fabrication is finished.

Including machine work we have around $5,500 in the motor, this includes the PFM kit. Target is around 700 reliable and managable horsepower. Engine management will be through a Megasquirt ECU.

Major tasks ahead will be stringer rails and motor plates (it currently sits on a wimpy three point mount), fuel rails, throttle body assembly, and another 200 or so others before we're done.

At same time we're working on the youngest sons red 20' Spectra, I'll start a second thread on that project after we get back from Desert Storm.

Cheers, Mark

[obnoxious001]

Is the exhaust going to clear the transom? Most of the open "race" turbo points up. Lots of heat coming out of that short little pipe, don't want to melt the boat.

[Maw]

Hi Barry,

The tips clear the transom by 1.5 inches (vertical) but we'll be running an insulated stainless shield spaced off the fibreglass by a half inch or so just to be safe.

The same for the tubine housings, we have the original insulated stainless steel shields which will be repolished in the final stages.

Cheers, Mark

[obnoxious001]

The other thought about pointed more upward might be to disperse noise, particularly since most places want mufflers and/or water in the exhaust now. It would also save having to shield the fiberglass?

[Maw]

We considered leaving just the initial 90* sections in place with an inch or two of straight added on for height. I was concerned that a kid wouldn't remember or care to cover them in the event of rain. I guess I could have added a weep hole at the botton of the base turn to drain any build-up away. We have four spare flanges and a few more turns to experiment with if we have any issues with this first pass.

Still have to add the O2 sensor bungs into the tubes so the weldings not done yet.

How noisy are turbo boats at idle? I was thinking that the turbine blades would add a fair degree of silencing to the exhaust note. Not so?

Thanks for the feedback!

[obnoxious001]

I had naugahyde covers made for mine with velcro. Even the ones you have won't be weather proof.

Noise isn't bad, as such. I have ridden backwards in a bunch of different ski race boats, the heat waves in the air above the exhaust is very clear,, just suggesting you might be better pointing them a different direction rather than letting you find out the hard way.

[.boatpoor]

Run them thru the transom with water. Don't think it will hurt performance but will kill the cool factor. I know what your thinkin but..........Good call on the heat Barry, people don't realize.:D

[Maw]

With his finals over Matt started the rails and motor plates. Bought two sheets of 1/2" thick 6061 alum alloy at the scrap dealer, 12" x 48", $75.00 per plate. Next picked up 6' of 2.5" x 2.5" x 1/2" thick 6061 angle stock. We used AutoCAD to draw the plates, transfered them to 1/2" ply wood for a trial fit, then cut the front plate out using a scroll saw with carbide teeth. Next he sanded off the corrosion with a jitterbug sander, then finished off on the buffing wheel. The surface isn't perfect yet but we figured it's probably going to get scratched up a bit before everything sits right. We'll finish bedding the rails tomorrow night along with cutting out the rear plate.

Cheers, Mark

[Wheeler]

Looks like it'll be a nice boat, what's the progress? :thumbsup

[Maw]

Looks like it'll be a nice boat, what's the progress? :thumbsup

Rails, blocks and plates are finished for the moment. They'll be polished and powder coated when we pull the motor out later this week so we can better get at the fuel tanks.

Tanks will come out this week so we can weld larger diameter fittings in place for the pick-ups, then add the return and vent lines. Tanks are already aluminum.

Pump is back from MPD. It's been given a coat of epoxy primary and will get a finish coat of white Awl Grip LP this week. We had the bigger shaft installed, a stainless A-2 impeller and inducer, then everything blueprinted. The loader is being built right now.

The boat now has an interior. We built the frames then sent them out to be covered in a soft white with yellow piping. We wanted to keep the "retro" look to the boat.

We've made the throttle body adapter for the EFI system.

I'll try and take pictures tonight and post them up.

Still trying to get it done for the "regatta" in early August.

Cheers, Mark

[Maw]

Since we're using an older draw-thru PFM kit as the starting point, but want to use EFI for the tuning and response advantages, we've made the following adapter.

Took a scrap 1/2" aluminum stock remnant from the front mount, cut and drilled it to a Holley 4500 mounting pattern using a scroll saw and the drill press. We then added the Holley 4150 throttle plate pattern to it, upside down. We've bought a new Holley 850 throttle plate off ebay ($15.00) to use as our throttle body.

A stock Holley main body to throttle plate gasket is used between the two and the adapter was tapped for eight 10-32 screws.

And no, I still don't know how to set the time and date on this old POS camera. :p

[Maw]

We've also built the two MegaSquirt ECU's for both Spectra projects this week. The injectors for the twin turbo project are Bosch 85lb/hr units. The fuel rails and mounts will be one of this weeks projects.

[Maw]

Rather than wait the rest of the summer to finish off the project we decided to run it naturally aspirated and shake down what's been completed to date.

We cleaned up an old Edelbrock Performer and Holley 850, then purchased a DUI distributor from Summit. We ran the motor over to a dyno shop here in HB where it was broken in for an hour, then a full power pull made. We had guessed around 450bhp and it gave us 442bhp at 5600 RPH with the spark arrestor in place and 87 octane pump gas. Maximum torque was somewhere below 4000 RPM, it was 507 Ft-lbs at that point and falling. Too low of compression and too small of a cam to make anything impressive, but it was built for boost. A drop in the primary jets would have put us over 450 BHP but we opted to keep it a bit fat.

I bought Matt a set of Bassett twisties, dropped the motor in and completed the project over a set of nights so it would be ready for vacation last week.

Sunday morning (8/1/2010) we got it onto Havasu where it GPS'd at an even 70MPH with two people aboard and full fuel tanks. Tach doesn't work, or at least doesn't work with the aftermarket HEI distributors, so we don't know what RPM it was running at that point. I'm guessing it was under 4,600 or so given the AA stainless impellor it's running.

Matt's happy with the performance it's providing and will be happier once the turbo kit and EFI are added this fall. This gives him time to get hours on the boat while competing the upgrade "kit". It's come a long ways from the compost pile we found it in. :D

His brother is happy that it's done as well, this means that we can put some added effort into finishing off his red 20 Spectra now.

Cheers, Mark

[ap67et10]

i had thought about doing a throttle body like that with a carb base, and possibly an entire carb, for a cheap throttle setup. I like that you are doing it, it looks like it should work really well with and old draw thru setup like that. how are you modifying it for a tps?

Andrew

[Flat Broke]

That's awesome!!!! I bet having it running so he can use it and get some seat time will cure any tendency to rush anything in the turbo department. Now he can learn the boat (they're really forgiving with a stock bottom anyhow), and when he adds more power, will be more able to identify potential handling issues that come with higher speeds.

Chris

[Maw]

We'll add a small aluminum block to the throttle cable plate to hold the TPS. We'll have a small bellcrank and rod up to the Holley throttle plate.

Making parts has become a bit easier lately now that we've picked up an older Bridgeport mill. Wish we would have had it from the start. Making the motor plates and rails would have been soooo much quicker with the mill, the scroll saw and file worked but took a fair amount of time and effort.

I was suprised how stable and well behaved this 19' hull is compared to our 20'. The 20 has always been "spooky" above 55, the nose never really comes up and it's continuously hunting left to right. We've added a droop and Place Diverter to it hoping to help this annoying trait.

Cheers, Mark

[RitcheyRch]

Very nice boat.

[Maw]

Very nice boat.


Thanks, it's been a fun project so far! (As if I needed one more project in my life)

[Flat Broke]

I was suprised how stable and well behaved this 19' hull is compared to our 20'. The 20 has always been "spooky" above 55, the nose never really comes up and it's continuously hunting left to right. We've added a droop and Place Diverter to it hoping to help this annoying trait.

Cheers, Mark

Mark,

Have you ever checked the pump angle relative to the keel? It could be that the intake is installed front high taking it over 4* and creating more downward thrust than normal creating bow steer. The other varialble could be hook in the bottom that could create the same problem. I've never been in a Spectra 20 that bow steered, but I've also never been in one that didn't have a droop and diverter. Considering most droop pin angles run +8* or more, that tends to require a little down wedging if you want to drill the nose to run through chop, so having bow steer with those setups is pretty unlikely excluding a hook issue.

If you need to borrow that Shoe to copy for the intake on your 20, let me know.

Chris

[Maw]

Thanks for the suggestions Chris, I'll check the installation angle and hook this afternoon. Thanks for the offer on the shoe as well.

Cheers, Mark