Do turbo engines have reversion issues?
 

Was wondering about reversion on a twin turbo application
what cam profiles do turbo engines like?
i was thinking turbo with dry tails wouldnt be too loud as the turbo breaks up and lot of the exhaust sound waves. Thanks for Any info you can share, RM

Dude, great question...

In most muscle cars a turbo will make great power with a stock cam profile. I would think that would remain true in boats also.

What I’ve been told is that the better an engine flows air (cam & heads) the more hp it will make with the least amount of boost

you know if blower cam grinds work well in turbo set ups?

I think the LS engines are much better platform than the old school sbc engines. The LS3 rect port heads flow 298cfm. Chevy CNC’s the ports and combustion chambers On some of the hi hp LS engines


The 6.2L iron block engine is the hot set up for a cheap bottom end and I would port the stock heads and run the oem intake and throttle body.

garret makes 47-55mm water jacketed turbos they will support 700hp! The air boat guys are getting 1500 hours out of a top and at 650hp in n/a on the ls engines. And 3,000 hours on a bottom end.

I think turning a prop on an airboat is probably pretty similar load to a boat.

I would be great if you learned how to put your engine tech questions in the CORRECT forum
https://cimg7.ibsrv.net/gimg/www.off...1825b03fec.png

I didn’t know there was a tech forum. Lol

This guy doesn't seem concerned about reversion ... (thumbnail is cropped. 1,700 hp, not 700!)
Oh, nevermind, he's running full open dry exhaust. Still a cool video and how I found the CleetusMcFarland channel which is mostly car racing. He has a 7 second 1/4 mile "streetable" Corvette. You can tell he's not a boater when he opens his mouth wide at 100+ mph.😉

[QUOTE=iliveonanisland;4764785]What I’ve been told is that the better an engine flows air (cam & heads) the more hp it will make with the least amount of boost

This is a true statement, but not what you asked. You asked if turbo engines have reversion issues. Based on how well a turbo works in a auto platform with the crappy cam profiles used to pass emissions, I would think those same cams could be used in a boat and not have reversion issues.

[QUOTE=ttuton;4764810]i probably should have asked if the turbo smooths out the pulses of the engine to prevent reversion issues.
If you have 4 cylinders feeding an exhaust manifold the turbo will always be spoiling some as soon as you start the engine correct?
There by always moving the air in the tails out of the tailpipes so reversion can’t happen once the turbos are spinning.
I wonder if on initial start up before the turbos spool up enough to prevent reversion could the water enter the turbos?

[QUOTE=ttuton;4764810]mild oem cams I doubt would cause reversion issues but aren’t we all looking to make as much hp as we can reliably? I’m wondering if the turbos have reversion issues so I can run as much cam ass possible to make as much hp and tq as possible with the combination.

Given that basically an oversize washer has been sold as a reversion dam then I’d think a turbo would be even more effective. I have zero empirical data or experience though. I did find this article interesting on the broad issue of reversion.

https://crateinsider.com/using-anti-...te-free-power/

thabks that was an interesting article. After reading it I would think a turbo would break up the sound wave pulse and all but eliminate reversion

I dont think turbo engines have reversion issues, like mentioned before the turbine is spinnig just after the engine starts. Now I have seen a video of a water injection nozzel on the inlet of a turbo and you can really see the reversion when the throttle is lifted. Also when I got my turbo cams from Comp, if I remember correctly, the exhaust side has more duration than the exhaust. And with a turbo, wider lobe centerlines are better.

Imo you shouldn't get reversion because you will almost always have back pressure in the headers.

Turbo engines don't need a lot of cam to make power, especially in a mild boat build. Keep the valve overlap at zero and it should live a long healthy life. Cam ground on a 114sep should be fine, depending on duration. Just an example, my last engine had 238/238 @.050 duration on a 114sep. My new cam is 238/242 on a 115 sep. Your not building n/a engines. Turbos are a different animal. Those 2 cams would make peak hp at 7000 and 7200/7300 with my healthy combo. You don't want to spin a boat engine that high.

Guys have made 1000hp on a sbf using 226/226 .512/.512 lift hydro roller cam. Let the turbos do the work.

LS engines have been beat to death. Guys can tell you what will break like clock work at what rpm and boost lol.

I suggest you go over to theturboforums.com and read up. A lot of good info.