HaxbySpeed

It handles like it's on rails.. I was hangin in the engine compartment at 85 reading my scanner with no issues. I think another 400rpm should fix his oil temps!

HaxbySpeed

See in bold above. Post some more details about the set up and what kind of O2 variation you're seeing on current ones. Are you running 8egt's as well to verify you're not seeing a false lean spike from missfire? - Alex

FIXX

i know what you mean,,i told him 5500 rpm's b4 he sent it to mark..

FogduckerIII

I was told by Mark (twice) that he "bumped" the stock rev limit to 5400rpm when I sent it to him......I have never been past about 4800rpm without the hesitation...... it was worse before Alex sorted out the fuel system, now I get to 5000rpm and it stutters, plus the low oil temps......

Just keeping my eyes open for a Holley "sale"......

RichardCranium572

Wow, did I just read that? EGT to watch lean spike?

I have a holley now to test and report. I don't doubt its' ability. I just saw this thread and doubt the haxor and his sales technique. I will report the truth. Sheesh, every product has good and bad...why beat up mefi? It was built in 1985.

HaxbySpeed

The Haxor! I like it, maybe I can change my screen name.
Yes you read right. Were you unaware that using EGT sensors is useful in verifying Lambda readings? Did you know that you can see detonation with EGT sensors? EGT probes on their own are really only good for checking cylinder to cylinder variations. If you combine your O2's and egt's it gives you a much better picture of what's going on. As an example of what I was asking Eddie: An individual cylinder misfire will show lean on the O2 sensor, you might think it needs more fuel but adding more fuel will usually make it worse. If you had an egt probe in that cylinder it would show a little cooler from the unburnt fuel, from the misfire, in the exhaust tube cooling the probe. There are a ton of variables in the combustion event that will effect both Lambda and EGT. As a tuner you want as much info as possible to interpret what's going on. With enough data you should be able to determine if you're having a rich misfire or if it's ignition related, or both. If you haven't spent much time tuning performance V8 engines using 18 O2 sensors and 16 EGT's then you would likely be shocked by what you find. Let us know when you get your Holley system fired up. Which system did you get and what's the application?

Haxor out!

HaxbySpeed

I've got a couple pulley's for you too...

Young Performance

The problem comes in with the quads. While I haven't used the 4.0 quads yet, I have done a bunch of 2.3 quads. It all boils down to blower speed. As long as you set it up to where the blowers will turn at least 15000 rpm at wot, it seems to be ok. It's when you get below that the distribution gets bad at lower rpm. It will straighten out as soon as it gets into boost. The worst ones I have seen are when guys are making 1000 hp or less with a 2.3 quad. They just spin to slowly. I have seen over 3 pts difference from hi to low in the afr's when in vacuum. It gets WAY better with DIS over a standard MSD setup, but the only sure fire way to fix it is to speed up the blowers. That's fine on a #6 boat, but what about Bravo boats. Most guys don't want 1200 hp on their Bravo.
I always run 8 egt's and you can even see a difference in them from bank to bank. They don't show a misfire with higher afr's from the excess of unburned oxygen in the pipes. From what I've seen with the DIS, I think you would have a hard time getting it to misfire. It is extremely hot.
No matter what, I want to run the engine in the boat for the first time. I understand what you're saying though. I'm pretty quick with a mefi, so I don't know how much time it would save me. Regardless, I'm not worried about that. I just want what's best.
As for the DIS, we either make it or have someone making what we don't, so we are in it pretty cheap. I have checked out some of their stuff though (58x trigger wheel, etc) and it looks pretty nice.
On the quads, I'm using an intake set up to accept port nozzles. Whipple can modify their intake, but I'm going another route. I'm going to run 8 in the blowers (4 in each) and 8 in the ports. THe 8 in the ports are more for trimming then anything.
I've been looking at a few different choices and certainly didn't want to rule this one out. The 555 does allow complete control over each injector throughout the entire rpm range. You will need 10 O2's to tune it correctly though. I believe the Vypex can do that as well. The good thing about using the 555 is that you can use Smartcraft gauges. The drawback at this point is that I can't tune it since I don't have the software.
Thanks for the reply Haxor.
Eddie

HaxbySpeed

That makes sense why the fuel distribution would be out when not in boost. It sounds like you'll be good to go with the injectors in the ports to trim the fuel down low though. I didn't know the 555 could do individual cylinder maps, that's really cool. The newer MEFI 5 and 6 are very capable boxes too but it's the same deal with lack of tuning software unfortunately. Another thing that you're probably aware of is that header design can have an effect on cylinder to cylinder distribution. Large dyno headers with a merge collector can have a tendency to overscavenge at certain rpms and conversely the headers in the boat can have a restriction in some tubes giving different results. It would be great if whoever's dyno you're using would let you set it up to run the headers from the boat to better dial it in. If not, are you going to use spacers to run the eight or ten O2's in the boat? Sounds like a cool project! -Haxor

Rookie17

I had this problem on a blower engine too. Not in a boat, but in some race cars we were forced to run supercharged due to an OEM relationship. The theory was the same though.
The solution we created was a little unorthodox but worked incredibly well. We spun the blowers pretty fast to help with the fuel trim issues you talk about, but ran turbocharger wastegates out of the plenum, controlled by the ECU managing the duty cycle of the wastegates.

We gained a little intake temp due to the faster blower speed, but that was more than offset by the different maps we could create by controlling manifold pressure almost irrespective of crankshaft speed.
The different torque curves we could create with a switch on the fly that changed maps instantly, real time under load, was a huge benefit.

I was concerned about the air fuel charge exhausting out of the intake, but because the injectors were in the port and a long way from the wastegate it was a non issue. We actually tried to see if the non used air was combustible and couldn't get it to light off no matter how hard we tried.

Not USCG approved for sure for a boat. But if you exhausted the non used manifold pressure outside of the engine compartment (exhaust) I would guess less of an issue.

I guess my point is, it solved our fuel trim issues at slower blower speeds. It also made for a much more docile engine with a switchable map (from the dash) when you didn't want to use all that power.

This was all on a tiny 4.6 Ford Modular engine running the 2.3L blower. If you consider the small displacement with only one 2.3 blower vs your big inch engines you can see that blower efficiency vs cubic inches are in a similar area. We were making above 850hp and 730tq at 7300 rpm when we let it eat. And could control the hp / tq and curves by bleeding off manifold pressure and building different map tables to suit. The "weak" setting out of the five different maps was a rain set up that only made 400hp / 370tq with a custom torque curve created just from managing manifold pressure.

Food for thought if you want to get crazy