Lightning or GiL
 

Pulling my motors for paint, going to invest in some exhaust, heads, cams...

Going dry tails for more aggressive cam profile.

Some people say GiL, some say lightning...

I only run once a year in salt water and flush immediately.

Please LMK your thoughts and why!

Thank You

In order to run Lightnings with dry tails I'm pretty sure you're going to have to have them custom made, so they are going to need to be new. Gils you can find with dry pipes pretty easily. As far as performance goes, there will be zero difference between the two. One thing to consider, aluminum manifolds are more reliable than a tubular style exhaust. Also lightings are not headers, in order to qualify as a true header the runners need to be at least 26", if I am remembering correctly. I would look at Stainless Marine- IMO they have the best design and are affordable, durable, and produce good power.

Here you can see where on a 500hp engine, the gils gave up 30ft lbs of torque , and 15hp or so to a set of CMI headers. That was onna 500hp engine. If youre intending on making more power than that, and going with a cam that actually can take advantage of scavenging , you might find a more substantial difference.

Then you get into header design, tube length, and primary diameter. There lies quite a bit of power in a big block exhaust setup, especially as the engines breathing capabilities increase.

Manifold wise, my choice would be the old eickert ones . Headers, cmi are great but of course pricey. The lightnings are a great piece, and they now offer big tubes and dry tail options as well.

The old eickert design that diamond now sells have long enough primaries to be considered headers I believe. - just looked it up, they say 32 inch runners.

I went to KEperf.com and I'm not seeing there headers?

These are the old eickerts

http://www.diamondperformanceparts.c...cat=282&page=1

If you have 24* cylinder heads it's a nightmare to change plugs with Gil's sometimes you end up having to re-move or loosen the exhaust to get the plugs out. The Gils also end up running into stock Alternator brackets/ alternator and have to grind on the manifold to get them to fit. For these reasons I would steer clear of the Gils. A lot better options for marine exhaust this day and age...

Eickerts are the best out there for both power and reliability, I ran them on one of my engines and gained around 2 mph with them compared to Stainless Marines. However I was spinning my engines to 5900, so they were taking advantage of the scavenging ability of this design. My midrange also improved. Good luck finding them used! I've been looking for 3 years, which is why I did not mention them. New I think their around $3600 with wet tails, dry would be more.

I was recently thinking about going to CMI sport tubes. I called a friend of mine that builds a lot of big HP engines in NC. He said that every single blower motor they have built and put CMI's on, they loose power on the dyno. That is comparing the same engine and swapping to Stainless Marine Gen III manifolds. The biggest issue with tubular exhaust is they will eventually leak. Over the years I've bought several sets of CMI's. Always told, no leaks, only to test them and have them leak. I have no experience with Lightnings, but there are many posts on here about guys going from Gil's to Lightnings and they gained zero. Maybe on a dyno there is some difference but not in a boat.

As Black Baja said, changing the plugs with Gils does suck. I've got Dart Pro 1's on my boat and it took me 2 hours to change the plugs on one engine. I don't think Eickerts would be any easier. The Stainless Marines are way easier due to the fact that you don't have to work around a water distribution tube under the manifold. The SM's are wide open, there is nothing below the manifold. What he also said about the alternator is true. I had very little room for adjustment. Mine ended up fitting fine but it is tight.
Stainless Marine's are pretty bomb proof and pretty easy to come by, so are Gil's but I feel Stainless Marine's are better.

For a big blown engine, give me the stainless marine GEN 3 manifolds anyday. Most marine tubular headers, are too small for big blown stuff. When youre building a 6000rpm big blown combo, those 1 7/8 primary and even 2" primary headers dont cut it. There could be a big difference on a 1000hp blown engine, with some basic cmi e tops, and cmi big tubes.

I dynoed my engine's the first time around with 2.25 inch primary id car headers with a 4 inch collector going into huge flex pipes that were like 8 inch. ..then dynoed at a different shop this year, with my stellings headers, which are 1 7/8, had my stellings tails that choke down to 3.5" tube, along with my sea pump, alternator, etc.

I was worried, becauase when putting the dyno sheets side by side, the new setup showed about 20 less hp, and alot less torque.

But, when installed in the boat, even after adding a few hundred pounds on the stern, adding another pickup on my transom, the boat is quite a bit faster.

Definately not a blown motor, just heads/cam forged 454.

#1 for NA BBC with decent cam: http://diamondperformanceparts.com/home.php?cat=282

#2 : Stainless MArine

Not to hijack , has anyone got any experience with the KE that Diamond sells ? Pulling a set of cmi sweepers off a side by side app. and would like to know the space left between motors . Those sweepers are a pain to get around and didn't hold up like price would suggest........ there E tops are pretty tough almost 15 years on a set no issues .

I would give away 20 hp a side to have piece of mind when it comes to exhaust manifolds

The only thing you will be giving up is bling factor, I am willing bet my last dollar that the KE's make more power than the CMI'S. . I had them on a single so I can't comment on access with twins.

If you look at the chart i posted in post 3, youll see the eickerts outperformed the e top cmis.

To OP I've had both exhaust in question. Lightnings were awesome and had a sound of their own and performed well. Had them on a 454 twin build with 502/465 hp cam with dart oval port heads. Engines made 480 plus hp and no issues with reversion what so ever. Gils are notorious for cracking etc and can lead to multiple problems if not caught right away. Not all of them of course however just a known fact. So in a nutshell between the two in question I would without a doubt go lightning. Easy to change plugs also.

On the other hand there is a few sets of stainless marine manifolds here on OSO for sale as well as on eBay and craigslist if I'm not mistaking. I do know anyone I've ever talked with who has had those really like them and seem to be trouble free.

Both Gil and stainless marine offer dry risers. Consider what cam your going with and go from there. Any of the manifolds/headers will perform well within your build and doubt you'd see much gains if your staying under 500 hp.

How many threads have you read on here that my Stainless Marine exhaust are leaking!!!!:)

The exhaust system on a big block chevy, is a major player in power output. I used to think years back, that bigger better exhausts, were for high rpm only racing stuff, and usually, when installed on a fairly mild bbc, would kill torque. That is just not the case.

A good exhaust system can substantially increase midrange torque, by quite a bit (as well as upper rpm power). We spend what seems like an eternity here, arguing over intake port volume, a few degrees of camshaft duration, seeking a torquey engine combo. Spend money on cnc port work, trick valve jobs and bowl blending, for better flow. When in fact, the results of all that work on the intake side, could have been achieved by simply bolting on a better exhaust system.

I have stellings headers on mine now, but pretty certain my next mod, is going to be Stainless Marine GEN 3 manifolds.

I'd like to see if we can organize an exhaust shootout this winter. Seems like about everybody is building a 700HP N/A engine these days. It be interesting to see what changes in output are seen at that level, by trying various exhaust setups on the dyno. Maybe try some GIL's, Eickerts, Imco's, CMI's, Lightnings, SM's, etc back to back.

I've seen quite a few engines come off the dyno that were dyno'd with big race car headers at the dyno shop, and end up really rich in the boat when the typical short runner wet marine exhaust is bolted on.

Im pretty sure that at 700HP level, running a short runner manifold, like a GIL, into a 3.5" gas tube, especially if water is mixing in, is a power killer. I'd imagine water in the tube, is probably choking that pipe down to the 2.5" volume range.

MT you are right it would be interesting to do back to back testing on the said exhaust on 700/750 hp engines. Regarding the OP's build I honestly doubt much gains would be seen from one exhaust to another on a 454/500 hp or less engine. We did testing but it was years ago on 496 manifolds and under 500 hp plus engines gains were very minimal if any.

Raylar did a bunch of back to back testing also and posted results on this forum some time ago.

NA, The collector (riser + added connection length + tailpipe) is just as important, if not more important, than primary length and this never, I say again, never, get's considered unless maybe in marine ' tractor header' applications.

edit in: Papasmurf just learnt this with his 'sleeper' Formula.

Helps scavenging big time. We use to mess around with that back in the drag strip days when dynos were far and few in between. Results would always very but knowledge was always gained regardless.

I've got hours worth of BBC exhaust reading material here in quite a few books. I'd rather not regurgitate any of that info, I'm already known as the regurgitating googler. :party-smiley-004:

But hey, check out this exhaust test from 1964 from Chevrolet Engineering Dept. Wonder if that had anything to do with the 427 Corvette exhaust setups.

Crap, here we go with the sideways pics again

Here's the thing.....reversion too.

So, even though max peak power doesn't change much, most of the curve can shift power upwards big time. One of the CMI's in Mild Thunder's pdf shows a lot more middle power than the others....I'm willing to bet this had a better sized 'collector.'

Now, staying on this, PapaSmurf had Diamond Performance's KE exhaust, and he was able to get his collector length to within a smidge of a best length and it fixed his reversion. KE's use a relatively short pipe connected to the manifold compared to many others,

I'll try to find the page,

He was killing 02's due to water..ie: reversion.

Okay,here:
http://www.offshoreonly.com/forums/f...epowering.html

and will quote it below:

Good find SB. I hope endeavor32 is reading this thread and or knows about the formula swim platform. He's been battling some brother sister issues with the engines in his formula. I would imagine he's read the thread but I've been wanting him to yank his swim platform off and leave it off for two years now so I can get a grin while he leaves dock and I'm working. What can I say it's much more entertaining than dealing with the public.

HA- It's in the overall plan. Once I find a nice aluminum swim platform the Silent Thunder is gone. That thing is heavy and really quiets the boat to much, even with 4 4" holes drilled into it. Also once I get the boat budget built back up, 2 sets of Eickerts are being ordered. I'll never be running a blower so for me they are perfect.

You know what is better than hearing me at the golf course? Doing circles around me with your boat! Getrdunn!

With dry tails on any of these setups should I concern myself with reversion???

I am definitely going dry tails...

Yes especially if you have a bravo drive and it gets stuck in reverse on a windy day it can and will revert. There is a cure for that as well... Tractor stocks or put your tails out the side of the boat.

I saw IMCO power flow have a pretty good power curve based on that chart, they are a little more cost effective then the KE stuff. Any thoughts?

I am assuming that they are testing the powerflow plus model ? which is right there with the KE price wise. Imco offers three different risers for these

http://www.imcomarine.com/cal_store/...-polished.html

It would be nice to see a updated test of exhaust manifolds with the newer models thrown in including the risers/ tails that are used

I'm curious why you want dry tails? Dry to the tip is loud, dry is stupid loud. If I ever pull the silent thunder off my boat I'll be running mufflers!

So I guessing finding something under $3k per side with dry tails is impossible unless I go with Gil/Hardin/Eddie marine/stainless marine style manifolds???

I was going to be running a .613 lift cam and don't want to take any chances. I have a molded swim platform so it should muffle it some.

What lift lets you run wet exhaust ? :party-smiley-004: I'm Just f'n around. LOL.

I don't know, but I know I don't want to spent all
This money and have water come back into my heads...

Does a molded swim step promote reversion? Am I reading this right?

I'm not saying that, but it definately traps a ton of water in reverse and decell.

Yea. I can hear some loud thumps back there when a wave hits and I kept the internal flaps in as well as the salsbury flaps for just that reason. Until I couldn't handle the interior flap's noise anymore.

Anyone heard of Kodak manifolds?

Hey Craney, I tried to buy your buddy (kmusto) IMCO exhaust but he didn't want to do paypal. He wanted me to mail him a check and when it cleared he was going to ship them...

Not real uncommon. Priority mail a bank check to expedite.