Thats awesome about the iat2s was just about to ask how they were.

42lb injectors are pretty much maxed out with a 2.9" pulley. a 2.7 is going to require more fuel, most go with 60lb injectors

Get yourself a nice set of bosch 60s and not the siemans. Youll thank me later

e Off road and marine use sets the rev limit a lot lower. Tacking out your car set to 7 grand is one thing because it stops there. Setting the limit at 7 grand in a boat or dirt car could have that thing spinning over 8 when it catches air. It would be just like doing a neutral drop when your at red line. So does he need the 60's if he sets the red line lower than you would? The 42's just run so good and the road course guys and my rail like the throttle response. Idk if it can be done or not in this different application so I'm asking....?

Thats a good question. Ive never used 42s, so i cant really comment there. I feel as if it is still going to be using quite a bit of fuel in the mid range, but every setup is different. My comment was more around which type of 60s to get if he were to need them.

I'm only seeing 67% duty cycle bouncing off my limiter(5500) with my 42lb injectors. I'm reducing my nozzle size to bring the rpm back down to 4600rpm. I don't rev like you guys so I don't have the volumetric flow rate of air and need less fuel. I will keep an eye on the duty cycle but I think I should be okay. I run my limiter 200 rpm above peak pump rpm.

This will give you an idea of the high side of typical rpm. As I said I have to reduce my nozzle size. I'm over powering my pump setup a bit.

that bitch sounds wicked

Looks and sounds great!

If you're keeping the revs down like that, by all means pulley down and get a huge bump in torque with no loss of blower efficiency at high rpms like we have on the street.

You could easily run a 2.6 or 2.5" pulley on a machined snout blower and not even need big injectors, and with the ice water cooling effectively, your temps would be fine. Engine would pick up 50+ lb/ft of torque right in the meat of the powerband where you're at all the time.

I love it :twothumbs

That's ridiculous.

You may need more than nozzle before you power up. That thing is not straining at all. The pitch changes when under load and I don't hear it.

This is awesome. That LSJ sounds right at home in a boat.

Getting ready to do some tuning we came up with a dry pipe to mount the wideband in.

https://cimg4.ibsrv.net/gimg/www.cob...db6c7bc4df.jpg

That exhaust has to be deafening lol. Good luck with the tuning

Plugs and Muffs!

Okay so I have the 2.6" pulley on and making 14.75 psi boost(195.5kPa MAP), with my IAT2's constant at 28C(82F) on long pulls. Seems to be running great. I had to drop a number of nozzle sizes to pull the rpm back down to 4500rpm.

Boat rips but what's next? I don't think I need meth at those IAT2 temps? With the low rpm's is it worth spinning faster yet or go to a bigger blower? Injector duty cycle is at 62%, so they seem happy.

I'll have to grab another video for you guys

Wow. Very impressive. That thing needs a stage 3 50 shot on a button for occasional hits.

wow thats insane. With those IAT2's you wont need meth ever.

throw a TVS on it lmfao.

Yeah those temps are amazing. No need for meth unless you want the octane to run more timing.

What is the top speed at 4500 and how small on the nozzle are you compaired to the adverage for that pump? Do they offer or recommend higher pitch impellers or are you still in range with that smaller nozzle. It's a balance. I'll guess you can hit 46 mph.

You can def turn the blower faster, i'd spin the whole engine higher but I understand the reason for your application of keeping it where you are.

At your low rev limit, you could run a 2.3" pulley and still be below max blower speeds. I'd pulley down more and see where you get. You will get more out of the efficency range of the blower but with your ice water cooling it shouldn't be an issue.

Thanks to AlexBC, https://www.cobaltss.net/forums/how-...through-80620/, others on this forum, as well as a couple of outside jet boat and offroad forums I have been inspired to start on my own project.

I don't have a pellet stove in my garage like you do... oh wait, I don't have a garage anymore either. So, I'm on hold for the winter until spring break up.

Alex, I'd love it if you could share some of your build process with me. While others have posted about mods they have done to their ectotec powered boats I have only found yours to be a home build. There are probably others out there but I haven't seen them.

I'll be starting my own thread at some point. I will be doing a supercharged 2.4l jet boat. I have not seen this combo yet. It's hard to even find any stand alone 2.4l supercharged projects.


https://cimg9.ibsrv.net/gimg/www.cob...6dfbdbca8a.jpg


The boat. 2272 SeaArk. Currently powered by a 115/80 Yamaha OB jet. Hit it's max with 2 guys, a week of too much gear, and about 750lbs of moose.

https://cimg5.ibsrv.net/gimg/www.cob...d788604e92.jpg

Almost ready for cleaning and possibly paint. I have all the supercharger conversions parts (I hope).


https://cimg9.ibsrv.net/gimg/www.cob...d43fd0fa02.png


Stock picture but I have the same on the way.

Are the Mercury sport jets at 200 and 240hp bad? Just wondering why you guys did not go with them and what the difference is in the pumps?

Here is your combo. It gets good around the 4 minute mark.

I personally think the 200 sportjet is a good setup if broken in and maintained properly. There are tons around and new boats being sold with them all the time. There is more versitility to setting up exactly what I want with the Ecotec engine and jet. Overall my setup will be far less than what I was finding for dropping in the 200 sportjet. I like the 4 stroke option more, the ease of maintenance, trash eating ability of 2 stage axial pump, and availability of parts and service. That and these are amazing little motors that can handle a lot of performance enhancements.
Just reading about all the Cobalt builds is fun and getting ready for my build has been a joy as well. I can't say the same when I looked at the SJ option. Boating is 1% necessity and 99% fun so I might as well have a blast building my boat.

Sport Jets are single stage and don't like pumping gravel, parts are expensive and most importantly they don't have forced induction. :D