Sniper EFI or stick with carb?
 

I’ve got single plane intakes and 850 Demon carbs for my 509s.

I was working on figuring out fuel system plumbing, pumps, etc, and was thinking maybe the Sniper EFI system would be a better choice with its O2 learning and monitoring.

Yay or nay?

Builds should be right around 600 hp.

I have always been a die hard carb guy, until I installed snipers on mine. I love it

I'll never stop telling people to go with a sniper, it has made tuning so easy, and with a closed loop system every startup, cruise, and full throttle run is perfect regardless of the weather. Plus I can record engine data and review it to diagnose any issues or improve the tune.

I’ll eventually convince myself and let go the carb wagon. I could t agree more I’m just not their yet. I just wanna get in the water! 😂

Looking at the Holley forum on FB... some people run into some serious issues.

Super Sniper is probably my focus since the ECU can do a little more, but reading recommendations for more extreme use points toward the Terminator X. Interestingly, the Terminator series is not listed under their marine offerings.

For you guys that have implemented, what do you carry for spare parts? I'd really hate to have something bite me in the arse twenty miles offshore.

I feel like I've really opened up a can of worms here!

You did.

The Terminator X is very similar to the HP. Built in MAP and can only use Bosch style O2's.

It all depends on how much you want to spend.

Sarcastic.....spare parts ? Something way more dependable than carburetors ? What ? ...,,,,, :wink....lol

Spare parts..... O2 sensor maybe

Quality rigging makes a huge difference on reliability. Most of the issues on those message boards are caused from hacked in set ups including undersized power wires and bad grounds.

I don’t believe the Sniper ECM is potted so that’s a weak point but haven’t heard of issues yet.

High quality marine pump, properly sized fuel lines with AN fittings, and fresh wiring will eliminate 99% of the common issues.

If you toast an O2 sensor it defaults to ultra rich instead of just shutting down. The beauty of the Sniper is if you boat in consistent conditions you can lock in a map and forget about the O2 sensor altogether just like jetting a carb.

With O2 sensors and good ignition, you can tune a carb to operate almost as well as efi. I am also sniper curious but the Inovate wide band has allowed me to get everything so tight, I don’t want to F with it. I’m going to vote for a good wide band set up and four corner jetting and go wring these things out already. It’s mid April man!

L
 

I agree never ever get a fuel injection system that has to have a correctly functioning O2 sensor all the time.

I suspected some of the issues were installation related. Some of the pics I saw of installs (boat-wise) were far from what any of us would do to test things

And I have no problem with over building electrical and fuel supply.

I think I’m pretty much convinced.

Is the 650 hp version (four injectors) enough for my 509? I don’t plan on building beyond what I have now; similar 9.5 AFR equipment builds are in the 625 range. For head room I can pickup the next level that gives another 600 hp of room to grow (lol), but I’d rather spend the money on the pumps and routing (better money spent).

And another thought was to just pickup a dual channel FAST AFR set-up and tune that way. Much less expensive.

I had my QF850 really dialed in using an AFR gauge, but when I did the rebuild I really didn’t feel like ****ing with that thing again. I still have less than five hours on the Sniper setup on a completely different beast so can’t say too much about it other than I love not pulling fuel bowls out in the middle of the lake or waiting until I get home to do anything.

Why would you have to retune it when ‘rebuilding’ it. Rebuilding a Holley is just
cleaning out internals and new gaskets and maybe needle/seat and acc pump diaphragm unless a real ratty carb which of course yours was not.

I was thinking he meant engine rebuild.

Probably. That makes sense. Thanks. I’m definitely not the brightest bulb in the room, so watch out for me. Lololol

One on the brightest bulbs here man!! And that was funny!!

New engine that was entirely different than what was in before. Only the block, crank, and heads were reused.

Thanks for bringing this up OP.

I just pulled the FA off my newly acquired engine and found the carb to be jacked up. Seeing the cost of a new Quick Fuel carb I about crapped. The Sniper is a fair amount more, but you get a lot of other parts as well.

Now, has anybody ever installed an O2 bung in a set of KE Thunder and Lightning exhaust?

I can’t comment on the O2 sensor, but regarding cost, make sure to account for the fuel delivery system upgrades that you’ll need. The systems sold under marine do not include pumps, etc.

** I can make you a nice deal on a 850 Mighty Demon!

I found out that there are not many people who will perform custom tuning on a MEFI 3 after rebuilding my Whippled 500EFI about 5 years ago. This is what initially sparked my interest in learning how to tune EFI myself. I started out knowing nothing about EFI and there has been a learning curve. Since then I have learned how to custom tune on my own by trial and error. Also by asking the right questions when seeking advise from Whipple and other EFI tuning specialists. Now I am not scared to install and tune any EFI setup on my personal projects. What I have found through my own journey, learning how to tune EFI, is that incorrect installation is usually the culprit for 9 out of 10 Holley EFI and Sniper problems. That being said, out of the handful of Holley EFI installs I have done, there was one Sniper unit out of the box that was only spraying fuel from 3 injectors. Holley sent out a new replacement within 2 days and included a return shipping label for the defective unit.

The Holley Terminator setup clearly states in the directions it is not waterproof and to mount the ECU in a location where no moisture exists. This would eliminate any intentions for marine usage. Running an O2 sensor in a wet exhaust will shorten the lifespan of the sensor dramatically. I would expect having to replace the O2 sensor every 30-40 hours. I only use the O2 sensor when it is in self learn mode or I am custom tuning it in a wet exhaust. Once the base map has been optimized and setup properly, there is nothing wrong with having it run in open loop. My next Whipple motor will be using a dual sniper setup.

Having the O2 sensor last depends on location within the exhaust and reversion tendencies of the cam profile. I run O2 full time in wet exhaust. Current sensor has lasted 10 years.

My set up is TRS with CMI headers and tailpipes. With the wet adapter I should be able to protect the O2 sensors pretty well.

I appreciate all the comments on experiences and direction.

I’ve spoken some with SystemProEFI and they’ve given me some good insight and a parts list, but I’m still on the fence especially from a cost to benefit standpoint.

I think adding bungs to my tailpipes and Howell adapters to O2 sensors with a AFR monitoring system would work give me the best bang for the buck right now. It’ll also get me in the water quicker.

I really want the injection, but the expense is way up there. I can do it, but I’d like to put the money into other areas if possible.

FWIW, I had one of the original Quickfuel carbs before Holley bought them and it was an excellent product and very user friendly and reliable. My current boat rarely leaves the lake or ventures very far from shore so if anything went haywire it’s no big deal. If I was doing serious offshore I may prefer carbs if I couldn’t muster up for a serious injection system. Plenty of folks have great success with the Sniper running offshore, but for me that’s my opinion on the matter.

The MPI system caused me some trouble about a good fifteen miles out in the middle of now where (ended up being a bad knock sensor). When you're having issues and there's no land to be seen in any direction, it gets a little spooky. Simple is better for me right now.

Not only does fuel injection provide excellent start up and drivability when in closed loop it provides better fuel efficiency and in turn increases engine life by not washing the oil off of the bore when over fuiling. I would vote for EFI and if your worried about getting stranded do the non-lock out distributor set up and carry a spare carb.

Spot on.
EFI starts paying for itself from day one in fuel usage, too many other benefits to list again.

Now excuse me I`m going to rip the Fuel Injection off my cars and install carbs , I don`t want to get stranded with that troublesome EFI
:cartman:

Carry a spare carb... lol!!

I’m not against fuel injection. If that’s the impression I made, that’s not the point I was really trying to get at. In fact I’m really excited about it.

Yes, I have some concerns with reliability. As more adopt the Sniper, it’ll show its reliability or lack thereof, and I’ll be able to make a more informed decision.

I’m also not in a position of spending another 4k on top of the other things that need to be done to finish the engines, get them dyno’d, then back in boat I’d really like to be boating this summer vs staring at a bunch of parts.

Sounds like you answered your own question. Carb it is .

For now.

How do you mount an O2 sensor in a set of CMI headers ? Had a friend ask me why I was still running carbs. He is a fan of the Sniper on his street car.

I’m going to put them in my tailpipes.

I have mine mounted it the tail. (yellow circle) I also have it mounted in an extension. I'll look for a better pic.
https://cimg5.ibsrv.net/gimg/www.off...379ac936c0.jpg

Any of you switch to the full Sniper Hyperspark ignition box, coil, distributor? I am not sure if those are meant to be used in marine applications.

No experience with the Holley ignitions, but after speaking with the reseller, it seemed to me that the small cap EFI distributor would be fine for what I was doing. He was in agreement.

Since that dist is Hall Effect, wouldn’t you be able to use a Tbolt IV/V distributor if you have one ?

Can the Sniper ECU accept a magnetic pick up distr ? If so, delco/merc est/voyager could be used, if you have one.