Gen 6 540 or Blueprint 632 in Magnum 27, Reversion?
 

Hi Guys,
I have a 27' Magnum with a #4 and a mild 454. I was going to build a gen 6 502 I have into a 700HP solid roller 540. I kind of wanted more power but I already have some stuff that will get me to the 700hp ish mark. Probably cost me around $15K to get there. I need to stay NA for hatch/back seat clearance issues, plus I like the simplicity of it.

However, A blue print racing 632CI 815Hp popped up for sale for about the same money. Its not the marine version, but I'd be freshwater cooling this anyways. The blueprint seems like a reasonable way to get into a big cube block and high flowing aluminum heads, plus make a bit more power and not be stringing out a smaller cube engine. They seem like a decent budget engine (I know those two words don't go together) Any giant red flags with this plan?

Here are the rough specs. Pretty much the same as their marine version except the cam is bigger, LSA is 110 instead of 112, with quite a bit more overlap, and the CR is 11:1 instead of 10:1. What's the rule of thumb on reversion? I don't want dry tails, I already have CMI headers that are dry to the tip. The boat has a transmission so the run of dry pipe is about a long as you can get. Can I run this cam as is or should I swap it out?

Here are some rough specs of the engine
Horsepower & Torque: 815 Horsepower / 800 ft. lbs. Torque

Cylinder Heads: BluePrint Engines Aluminum Cylinder Heads

Compression Ratio: 11:1

Camshaft: Hydraulic Roller Cam - .698 Intake / .698 Exhaust Lift and 272 Intake / 282 Exhaust Duration @ .050 - 110° LSA

Pistons: Forged

Crankshaft: Steel Crank - 4.750" Stroke and Forged 6.635" Rods

Fuel Recommendation: 91+ Octane Approved
PriceRegular price$17,69900


Looking for opinions on these engines and this cam.
Thanks Fellas
-Chris



Link to non-marine version:
https://blueprintengines.com/collect...c2ccf955&_ss=c

Link to Marine Version:
https://blueprintengines.com/collect...621169d3&_ss=c

https://cimg2.ibsrv.net/gimg/www.off...ca5d3aced4.jpg

here are the key differences
Blueprint 632 car engine:Compression Ratio: 11:1

Camshaft: Hydraulic Roller Cam - .698 Intake / .698 Exhaust Lift and 272 Intake / 282 Exhaust Duration @ .050 - 110° LSA


Power adder 632 engine:

Compression Ratio: 9.6:1

Camshaft: Hydraulic Roller Cam - .698 Intake / .698 Exhaust Lift and 272 Intake 282 Exhaust Duration @ .050 - 110° LSA

Marine 632 engine:

Compression Ratio: 10:1

Camshaft: Hydraulic Roller Cam - .647 Intake / .647 Exhaust Lift and 258 Intake / 266 Exhaust Duration @ .050 - 112° LSA

right off the bat since your using a dry exhaust to the tip, reversion MAY not be a problem, but depends on your idle speed. the compression may be a problem at 11;1, that using 91+ octane fuel all the time may be a huge expense that could put you in shell shock especially this summer. The pother thing I see is the high compression engine makes peak HPO at about 6100 vs the marine one at 5700. Im guessing you are using a TRS drive, but even if your using a bravo, one of the things Ive heard is that spinning the TRS at that high of a speed heats the crap out of the oil. A Bravo can run that high also but then a drive cooler would be mandatory. And you pushing the limits of what a TRS drive can normally handle power wise.

I'm not too worried about the fuel, this is just the fun boat. The drive is a big shaft SSM #4 so strength is enough for 800HP. I'm just afraid the CAM is a bit too sporty for marine use. I'm going to call Blueprint and see what they say also. Good catch on the torque curve, I didn't notice that.

CMG223,

Total layman, here, but here's the "rule of thumb".... Do the math on your cam. If the exhaust valve is closed before the piston starts back down, reversion is nearly impossible. I cannot speak to how this translates to performance, however.

For the sake of discussion... Are you sure you can't squeeze a Whipple in under your deck lid? You'd be surprised how low a Whipple is, even with an intercooler, compared to a flame arrestor, on top of a carb, on top of an intake manifold. I'm sure Whipple can give you some dimensions from motor mount to top of the blower. Hell, there's undoubtedly quite a few on here that can get you that info. A ProCharger, for that matter, will add zero height to an engine, and a minimal amount to the front end. There are a great many voices of authority (of which, I am not one of) who will likely steer you away from a 632 (rod angle) or a super high CR build in a marine application, simply because of the extended duty cycle. Huge cubes and/or super high CRs are typical in drag applications, where WOT is limited to seconds at a time, but they don't necessarily work for marine use, where you may be putting it on the firewall until you need more fuel. A Whipple/ProCharger on a mild build 540 will get you to your HP goals and run forever.

Primarily commenting to hear/read the responses you get.

Thanks. Brad.

I can't help but wanted to say, beautiful Magnum. Good luck with your build.

Padraig

Did you see this ?

This engine features .300 raised exhaust ports and .400 deck height increase over OEM.

That’s more cam than most boat guys would run. But the engine is reportedly very reliable in street cars. It dynos 830hp.

The head is unported version of an AFR. With these dissappointing flow numbers, there is a ton of potential left in the heads if cleaned up.

https://cimg7.ibsrv.net/gimg/www.off...43d2729410.png
https://cimg8.ibsrv.net/gimg/www.off...6c08b048df.png

The difference in those flow numbers suggests there’s up to 75hp available with porting. With a profiler tunnel ram? Could be an absolute beast 900hp engine.

I’d have a head guy port them and add some chamber volume too to drop the compression.

I don’t know about cam life. But you could buy a milder summit cam and swap it too.

https://www.summitracing.com/parts/s...make/chevrolet

Those little single engine straight Vees don’t seem to do to well with huge power though. So anything over 700 may be pointless anyways.

They will not endorse the idea. You’ll be on your own. A 1 of 1 experiment. But like I said, some street and strip car guys have run them up to 30k miles. So that’s encouraging. But you are going to put far more high rpm hours on them. The springs are daringly light. Kinda how Merc did it too though.

This blower may fit under you hatch. 700hp on a 502 easy. You might be able to reuse your crank too depending on what it is.

https://theblowershop.com/shop/super...2v-street-8mm/

I did see this. Were you thinking the added height would interfere with my hatch? Does the raised exhaust port height typically affect how the exhaust holes line up?