Reply With QuoteMy 2 cents. You need to get over 450 HP for after market exhaust to do any good. Stock BB mercruiser manifolds are better than most people think. Keep the Gils and invest in more horsepower
Does anyone have experience with IMCO exhaust manifolds? As many of you have read here, I installed Gil on my 454 Mag MPI (385hp) along with the usual other mods (flame arrestor, adj. fuel pressure reg., reprogrammed ECU) and got ZERO performance increase at WOT.
I just talked to a guy at Teague. When I was telling him about my current mods, he stopped me as I said "Gil" and he said " . . . and you got 0 - 2 mph, right?". He said, "put your Gils on E-bay and put on Imco Powerflows." He claims that IMCO Powerflow manifolds will get me 4-6 mph easily. He claims they have many customers who have had the same experience I've had. He even says they sell Gil but don't recommend them (although, from what I'm hearing, nobody can get Gil's right now).
Am I being fed another line to convince me to throw yet another $2,000 away ???
Ric
My 2 cents. You need to get over 450 HP for after market exhaust to do any good. Stock BB mercruiser manifolds are better than most people think. Keep the Gils and invest in more horsepower
Well, I have been trying to invest in more HP, but everyone says there isn't anything short of a blower for an MPI motor.
Teague also said they don't recommend any cam upgrades for the MPI motors as they have seen no cam/ECU packages that work well.
Dennis, do you have an opinion on this Gil versus IMCO thing?
Ric
This is a very touchy subject because of the many manifolds on the market. I was actually threatened with a lawsuit about what I printed about exhaust systems in my book.
I think they are both excellent. I know Fred Inman at IMCO very well and he makes an excellent product as well as being a really nice guy. I have also installed Gils and talked to the guys at Gil and they also really know there stuff.
What I said in my book stills goes.
I honestly wouldn't think that there would be much of an increase or decrease switching from one to the other! Both exhaust manifolds increase performance by lowering backpressure and neither have long enough runners to create a scavenging effect.
Dennis
PS It wasn't either IMCO or Gil that threatened me with a lawsuit. They are way too cool for that!
I put a set of IMCO's on the boat when it had a stock 454 Mag. Didn't really see any big speed increase, but the low end was more noticable. It also seemed like it was easier to hit top speed in more varied conditions. They must be pretty well built as well. Charlie and I were out tear assing around at the last years Parade of Lights and I blew the outlet hose off the seawater pump at 100 mph eek! When I slowed down enough to hear the alarm, it was steamin'!! I thought sure I'd blown the whole mess up. Even bubbled that thick black powdercoat that came on them in a bunch of places. Pumped out the center pod, hooked the hose back up and she's still running good. Just had to have the manifolds recoated!
Craig
[ September 19, 2002, 06:37 PM: Message edited by: Craig ]
It's funny, but the largest performance increase I've experienced in my boat was after I scraped the corrosion off the contacts inside the distributor cap. The corrosion was not bad enough for the motor to miss, but I gained 75rpm after cleaning the contacts. I just looked at them again tonight, and even with a new distributor cap about 6 mos ago (25hrs), they have some corrosion again. Oh, well.
Ric
I ran IMCO's on my 509 in my jet boat and did see an increase over the stock log exhaust. I am going with a bigger 540 inch motor for my v-drive and will run the same exhaust.
When I bought my IMCO's, I thought the Gils were better. I think they were more $$$ too.
If I were to buy new exhaust, I would go with CMI's or Lighting's.
Brent
Craig:
I put a set of IMCO's on the boat when it had a stock 454 Mag. Didn't really see any big speed increase, but the low end was more noticable. It also seemed like it was easier to hit top speed in more varied conditions. They must be pretty well built as well. Charlie and I were out tear assing around at the last years Parade of Lights and I blew the outlet hose off the seawater pump at 100 mph eek! When I slowed down enough to hear the alarm, it was steamin'!! I thought sure I'd blown the whole mess up. Even bubbled that thick black powdercoat that came on them in a bunch of places. Pumped out the center pod, hooked the hose back up and she's still running good. Just had to have the manifolds recoated!
Craigoh I remember it well!! It looked like you caught fire!!! steam and smoke billowing out the engine hatch.... I'm was happy as hell that it was a field fix............................................... . I didn't wanna tow ya all the way back hehehe
wink
I've always wondered,why go with elbow top headers when you could get long tubes like Lightning or CMI sweepers?It seems like merging the cylinders so soon after the exhaust port makes elbow tops kinda like an exhaust manifold.Just out of curiousity Charley,what did you have on your quad Rotor?
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