twin turbos on 330's super budget build Which turbo's?
#21
Registered
I want to use ebay internal wastegate turbos on my 330's The engines have the larger oval port heads. Im going to mount them to Gil manifolds. I want to do a low boost (5 lbs, maybe 7 lbs) no intercooler. This is mainly for the WOW effect at the dock. Im am thinking that 500 hp is a safe number on the stock blocks. Ive looked at HX35's but not sure if they will even spool at 5psi. Anybody have suggestions from experience. Id like to do internal wastegates so I dont have to deal with that plumbing. This is going in a 1978 30' Scarab.
learn how to read a compressor map,
https://www.enginelogics.com/read-a-...ompressor-map/
HX35 will require a rebuild if you are going to do a draw through carb, which brings me to my next point.... EFI. yes there is learning involved by you can dial the setup way better once you learn. plus you get knock sensor that can start to pull timing and get progressive in the timing pull the more times it detect knock.
no intercooler? why?!? you have unlimited cooling potential and you are not going to use it? that's just dumb. plus you are trying to stave off detention
Patrick, you don't need wastegates at all for what you are looking to do. The original Merc 475's had a 3/4" hole in the housing to bleed exhaust prior to impeller so you could do the same. The 3/4" hole netted around 3-4 pounds of boost so maybe 1/2 or 5/8" hole would get you 5 pounds. I say go for it, would look really cool when you open the hatches.
#22
Platinum Member
Platinum Member
Thread Starter
by 330s i assume you mean HP, so they are 440 cubic inch motors. HX35 will spool on up and probably choke the motor up top. you can easily spool up on of those on a 350
learn how to read a compressor map,
https://www.enginelogics.com/read-a-...ompressor-map/
HX35 will require a rebuild if you are going to do a draw through carb, which brings me to my next point.... EFI. yes there is learning involved by you can dial the setup way better once you learn. plus you get knock sensor that can start to pull timing and get progressive in the timing pull the more times it detect knock.
no intercooler? why?!? you have unlimited cooling potential and you are not going to use it? that's just dumb. plus you are trying to stave off detention
awful idea, when did they spool up? use an internal WG and move on. you normally want power thats why one would use a turbo, so you want it spool up ASAP then bleed exhaust energy to control. unless you are trying to delay spool up to protect the stern drives
learn how to read a compressor map,
https://www.enginelogics.com/read-a-...ompressor-map/
HX35 will require a rebuild if you are going to do a draw through carb, which brings me to my next point.... EFI. yes there is learning involved by you can dial the setup way better once you learn. plus you get knock sensor that can start to pull timing and get progressive in the timing pull the more times it detect knock.
no intercooler? why?!? you have unlimited cooling potential and you are not going to use it? that's just dumb. plus you are trying to stave off detention
awful idea, when did they spool up? use an internal WG and move on. you normally want power thats why one would use a turbo, so you want it spool up ASAP then bleed exhaust energy to control. unless you are trying to delay spool up to protect the stern drives
2. no intercooler because of even more cost and complexity. I would need 2 intto 1 intercooler, mounts for it, water pickups, hoses. so by the time that is all done, Im looking at another 1000 per engine.
3. the reason GB didnt use waste gates back then was because of added complexity im guessing.
#23
Registered
1. no EFI, not in the budget. A basic EFI system would start at 2000 per engine-. The new system will be blow thru. I already have the carbs and fuel pumps off my other turbo engines. M&W had a bolt-on blow thru system that added 90 hp to a bone stock 330 back in the 70's/80's with no changes to the engine. They even used the stock Q-jet carb.
ebay is your friend.
https://www.ebay.com/itm/Universal-w...frcectupt=true
https://www.ebay.com/itm/Aluminum-Y-...frcectupt=true
more like +250-300/per motor
use that link you can do a rough calc of what your turbo discharge temps will be. you want to pull that heat out of the intake charge. you will want to remove any increased change of pinging or detention, as stated above those motors have a weak bottom end. what going to be more expensive, doing it right or doing it twice and right?
#24
to throw another idea in the ring, what about finding some LQ4 motors, super strong form the factory, tons of cheap twin kits. make the same power if not more AND then you have a ls twin turbo boat:P
#25
Registered
trying to keep my whole swap and conversion to EFI under $1,500. spent a lot of time researching this.
#26
Registered
I don`t mean to discourage you but this is a stupid idea, hope that helps.
#27
Platinum Member
Platinum Member
late 60s there was a company Daytona marine that put twin ray jay turbos on a 427 tall deck truck engine think it made 425hp intercooled at like 3800rpm blow through carb. Water jacketed turbo housings was very nice set up. And was fresh water cooled.
#28
Charter Member
Charter Member
the early '80 s Gale Banks twin turbo kit for that era 330's was adveratised as a 425 hp output. I saw one engine spit the rod out of the bottom of the pan but otherwise they did as as expected. when comparing that setup in a 30 Scarab with the Gale Banks twin turbo kit against one with the factory Mercruiser HP 475 twin turbo the 475's seemed much stronger than 475, low 80's vs mid to high 70's same hull but the 475 setups had a higher X and speedy II drives vs the std 330 with TRS. The 25" merCleaver was probably limiting the TRS boat also. Good Luck
#30
artselectricinc.com
Platinum Member