HP 500 with KE exhaust reversion?
 

Hi guys. I'm putting a HP 500 in my 1998 Cobalt 252. I would like to keep the Captains Choice if possible. Seeing everyone makes a a specific exhaust riser for the HP 500, because it sucked water so bad, I'm wondering if the Keith Eickarts would still revert?

stock cam #169611 .576/.598 222/230 110 LSA

The engine swap will be happening soon, so if I cannot use the CC, I will be removing the Y pipe and blocking off the exhaust opening on the Bravo.

Thanks for any input about this

Are you refeering to the KE aluminum headers? If so I can not imagine an issue with reversion with the hp 500 even with 741 cam. If you have reversion with that set up then I'm Concerned about sucking water up from the lake with my stellings dry to the tip above water platform.

the original hp500 carb'd cams were know to revert,even w/ the tall risers.you either change cam to the 731(a little bump in power) or as you idle in,keep the rpms up and then in neutral,rev it up and shut off at the same time.it blows the little bit of water out.

I had the a HP500 carb w/ KE Exhaust in a 28 Velocity, ran strong for ~150 hours, no reversion issues at all. KE's have full 32" runners, so the water has a long way to run backwards. In fact I have (2) new sets of KEs that I'm going put in the Skater 1 of these days...

I wouldn't run the switchable exhaust with Carbed HP500's unless you swap cams.

OK, so no CC.

I will be eliminating the Y pipe then. Thank you

Yes, I was referring to the Thunder n lightning aluminum exhaust

So the taller riser "fix" still didn't resolve the issue? Damn....

Did you have the short 6" extension that comes off the manifold? Or was it longer/closer to the transom?

X,
The shorter standard 6" Bravo wet tailpipes.
Skater Dean

I called diamond perf today and asked about the KE TnL's and he felt I would most likely need dry tail pipes with that cam.

Anyone got any suggestions on what exhaust to use with the stock cam?

Mechanic has already got my boat in the shop with the engine sitting on the floor next to it. Might be a little late to try swapping cams now.

From where the tail bolts to the ke header to where the outside tailpipes end into the atmosphere should ideally be 19” long. 18”-20” will be okay. This should help with reversion as it’s near an ideal length. Search under my name and the KE Headers and lightning and thunder exhaust. You’ll find sone good info and an example of someone who had reversion until he cut his length to that.

I can’t give you promises but can math thru science and real life data.

+ Just saw Dean Ferry said used same engine, cam, short 6” tail and had non-issues. He’s been-a perf boater and on oso for long time.

X,
I just sent you a PM.
Tx,
Skater Dean

Great info as I too am wanting to repower my 252 Baja Islander...and am torn between a 502 Mag EFI or HP500 EFI, with the goal being to use as much 'stuff', like exhaust...from the 454 that is in it.

I was contemplating getting the Baja 252 open bow, or my Cobalt 252. I like the sporty look of the Baja and the GF liked the luxury look of the Cobalt. Whichever had to have a 454 MAG (385 HP) or a 502 (415 HP) At that time I couldn't find a Baja in good condition, and was very tough to find one with the engine I wanted. (Most were 496 mag with 375 HP) So we got the Cobalt

Well, I can honestly say this has been a learning experience for me. I have the 502 MAG (415 HP) you are contemplating. It's a robust engine and pushed my kinda heavy Cobalt 252 to 63 MPH (4500 lbs dry weight) I did have the fuel injectors cleaned/flowed. Installed the Hardin Marine Seaward exhaust for use with captains call, installed the older style Flame Arrestor and matching Throttle Body as I read that FA flowed the best. New plugs, cap, rotor, wires, and control module. The MPI engine isn't too bad on fuel if you're just cruising. Lots of parts are available for it, but the Achilles heal IMO is the oil cooling system. It's adequate for the stock performance, but needs addressed if upping the HP. If left alone, the engine is supposed to be nearly bullet proof. I've seen some people say about 1,000 hours is achievable before any major overhaul is needed.


The HP 500 EFI is whole other animal. I'm not sure what ignition you have? But most likely will not work with the HP 500 engine. Which I believe is the MEFI 3. So you would need to replace that. The stock exhaust from your 454 would be a MAJOR step back if installed on the HP 500. It came with headers from the factory. It also requires more regular maintenance VS. the black engine.

So I don't think there would be much you could "switch over" from yours to it. It would be more of a remove your engine, and replace it with the HP 500 "drop in ready" engine. (which is what I'm doing)

If you got any Q's just ask. I'm learning the hard way and can teach you what NOT to do..... ;)

Please note that the HP 500 EFI is not plagued with the same problematic camshaft as the engine I am asking about in this thread. They resolved my problem by installing a different camshaft and using the headers for the fuel injected engine

Pretty sure I've already seen what you're asking me to look up. I searched every thread I could when it comes to the HP 500 carb engine. Thank you for sharing that info though. It's something i will be paying closer attention to now.

Yes.
HP500 cam is 222/230 at .050” with 110LSA . Merc installed Gill exhaust

500EFI cam is 230/236 at .050” with 114LSA. Merc installed CMI headers.

Thanks for taking the time to post that...very much appreciated. And I hear you on the hard time finding a boat...I looked for two years to find the one I got, it is PERFECT except for needing a bit more power. Will probably go the 502 Mag EFI route but haven't been able to find a good one of THOSE, either, lol!

In all honesty, your 454 Mag is 385 HP and the 502 Mag is 415 HP That's not worth doing an engine swap if you ask me. Going to 500 HP would be worth the swap.

Just curious, what speed are you getting from that boat and engine combo?

You will have no issues with a stock HP 500 and the KE manifolds. I've run them on several engines: a 439 with a custom cam, slightly larger than a 741, a pair of 454s with 741s, and a set of 509s with 741s. No reversion issues at all. The 439 used the standard short tails, the other two engines used custom through the transom tails.

IMO they are the best option so long as they work with your set up.

Thank you for that. I have been reading all the past threads about this engine and the KE exhaust I can. Yourself, SB, and Dean have all been supporters (along with a number of other members and other sites as well) of the Thunder n Lightning exhaust.

So this is where I'm at right now.

I have no exhaust. 180 hrs on engine. Valve springs have been replaced. Engine is already installed into the boat (cam swap is off the table for now)
Bravo 1 outdrive. All new maintenance parts replaced. (bellows, gimble bearing, U joints, reverse cable, seals, and fluid) Teague billet top cap installed. Simrek drive shower installed. Y pipe removed and block off plate installed

Here's what I have. 1998 Cobalt 252 bow rider 4,500 lbs dry weight Bravo 1 (1.50) had the 502 mag MPI turning Mirage plus 23P 5200 RPM at 63 MPH with 2 people on board and half tank of fuel. The boat will be used on Lake Erie, so 2-3' choppy conditions is normal. Bennett dual ram trim tabs have now been installed.

I opted to install the HP 500 because I want a little more speed. Not so much more that I need to install hydraulic steering or upgrade my out drive to something else. And the look of that blue engine under the hatch really looks great.

I've been doing a lot of reading of old threads and am kind of confused, so I am looking for some more input from you guys please.

I have the Hardin Seaward exhaust manifolds from my 502 mag already. All I would need is to purchase the HP 500 risers for $1400 and I can install that.
PROS: cheapest option, looks good
CONS: lose some of the HP I was hoping to gain from the engine swap

I have been researching the KE Thunder n Lightning. Lots of positive reviews
PROS: Tuned length exhaust with great HP output for NA engine. Reliable and durable
CONS: Cost nearly $4k Big, not easy to work on engine with them installed. Have read impeller failure (lack of cooling) can lead to catastrophic failure. Requires more $$ to make them look great

Also leaning towards the CMI Fusion headers.
PROS: Good performance. Look great. No need for tailpipes and clamps. Easy to work around installed on the engine.
CONS: Cost around $4k. Not many reviews as of this post. Are they prone to cracking/leaking?

I have sunk a fair amount of $$ into this exchange already, so I'm not looking to spend another $4k for just an exhaust. But at the same time, I want to gain the most MPH I can since I've spent so much already trying to achieve just that.

So is the little bit of HP being left on the table using the Hardin manifolds worth the extra $2500 cost?

Input please. Thank you

I have no real experience in this scenario but so far I’ve never heard of anyone regretting going with the KE setup.

Been running KE's exhaust since 95 on many motors, all over 750 hp, up to 1050. Not one failure. Have a dyno comparison on 1050 motor with KE pipe versus CMI big tube. Difference was like 15 hp. Now before switching to KE, I ran Stellings and CMI. No comparison in product issues. If you loose cooling and don't catch it, not good probably with any exhaust.

I understand KE TnL is a good exhaust. So you guys feel they are worth the extra $2300 over a set of Hardin manifolds?

Obviously I can sell the Hardin exhaust to re-coop some of the $$ spent. I've read some manifolds MAY give up as much as 40 HP compared to a header. Would that difference in HP be enough for you to pay the price difference?

I cannot talk specifically about the new Seaward system from Hardin. My expericane is Gil and Stainless Marine both performed exactly the same. I am sure Seaward will fall into the same category. You will gain hp and speed with the KE manifolds I am sure of that. How much? Probably around 1.5-2 mph. So is the gain worth the money to you? The CMI Fusion will be no better than what you currently have. It is just a short tube stainless manifold, it will not scavenge the exhaust any better than what you currently have on your boat. Does it look cooler? Yes. Perform better? NO.

If you are going to do the swap, stick with the KE. Anything else in your budget will be a lateral move.

That's exactly what I was thinking as far as gains. Thank you for that.

Decided to go with the TnL exhaust. Problem is, it's 1 month out before it arrives. 8(

Been a while since this has been posted, so in case you have never seen it (used to be posted alot)


https://cimg3.ibsrv.net/gimg/www.off...1ac70c5d9.jpeg

Here are better charts:
https://www.offshoreonly.com/forums/attachments/general-q/444097d1301322986-exhaust-dyno-charts-copy-exhaustdyno.pdf

Posted in this oso thread:
https://www.offshoreonly.com/forums/...no-charts.html

I have seen the first graph, but I've never seen the other charts. Thank you for that.

It's a double-edged sword. It shows how well the KE's perform, but at the same time only reinforces what I had thought earlier. A good set of manifolds is going to give up 15 - 25 HP to the KE's. But in reality that's just 1 - 1 1/2 MPH.

I can purchase just the HP 500 risers for $1400, or the whole KE exhaust for $3700. (sell off my exhaust and the total comes to around $2500)

So is the additional 1 - 1 1/2 MPH worth $1k? Dam.....

As someone that’s had leaky headers hydrolock an engine and have read of similar issues with just the risers I find the value in the KE units a value in peace of mind myself. Headers have proven to largely be a waste of money performance wise unless you’re pretty deep into the engines but manifolds with SS risers also have issues. That’s just my pov and not nearly as relevant until you’ve lost an engine. No guarantees but it will send you looking to improve the odds.

One month later and they still being machined. Then need to go to powder coat. UGH... This is getting really close to boating season. And I still haven't fired up the new engine yet because of the exhaust.

After speaking to Bill again., it's looking like the TnL exhaust might be arriving in June. So I found a set of CMI Fusion headers in stock and bought them. Hopefully I'll be on the water by Memorial week end.

Still trying to decide if I should cancel the TnL order or not?