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wally
08-08-2000, 05:54 PM
What can be done to increase horsepower on this engine? Whipple Superchargers says that this engine is not strong enough to handle extra HP. What needs to be done so that a supercharger can be added?

Jerry Buckner
08-15-2000, 07:26 PM
Originally posted by wally:
What can be done to increase horsepower on this engine? Whipple Superchargers says that this engine is not strong enough to handle extra HP. What needs to be done so that a supercharger can be added?
You would need to make sure the engine has forged pistons, a forged crankshaft as opposed to a cast crank and good connecting rods. It would also bennifit from a camshaft upgrade for better breathing and then of course it has to be able to get out so a good exhaust system is a must. CUBIC DOLLARS!
Good luck.

Rod in CA
08-21-2000, 05:40 PM
Hi Wally, I have a similar set up in my Baja 252 ('96) with a 7.4 MPI (330hp). Before last season I installed a Whipple blower and am running 6 pounds of boost at sea level. I run 92 octane pump gas w/o octanes boosters. I have two seasons on it and have run over 40 hrs. with no problems at all. I like to go fast and have a tough time pulling the throttle back. It is a silly little character flaw of mine. There is one thing I should mention is that alot of this time is at Tahoe (6250 ft altitude). As you know the power is significantly less up there and with the Whipple intercooler I have never seen the EGT light nor had any indication of detonation. At sea level the same is true, but then I have much lest experience down here. I think Whipple is being conservative. It has been my experience that the Bravo one is more suspect. I find new vibrations at various trim positions that didn't exist before. I do run it hard. The engine is solid so far.
So to answer your question, if you have a low time engine and you don't go above 5 or possibly 6 inches of boost, then you shouldn't see any problems. Another thing is that you should not change your rev limiter! The cast crank and pistons won't take more RPM. But that is where the beauty of the Whipple is. It makes tons of torque at relatively low RPM. So all you need to do is go to a bigger prop and keep the RPM the same. I went from a 21P to a 27P 3-blade Mirage (25P at Tahoe). Speed increased from 66MPH to 78MPH @ sea level and from 57 to 66 MPH @ Tahoe as measured by GPS. I may change pulleys to 7 pounds of boost for Tahoe and go after that one 35 foot Fountain with twin engines I haven't yet been able to catch... barely!
Another benefit of choosing a blower is that you have to do nothing inside your engine except bolt it on. A blower doesn't need to have expensive "open" heads and exhaust. The engine isn't sucking in the air charge, its forcing it in under pressure. Since you are using the stock RPM range, a new cam shaft will not buy anything either. More duration will not improve airflow much or at all, and neither will lift. Again you are blowing pressurized air mix into the combustion chamber. The stock cam idles perfectly at idle boost. Docking and trailering are as easy as when the boat was new. My stock exhaust works just fine too. It is a through-transom Corsa Quick and Quiet system. SOUNDS GREAT.
The only drawback is the cost. With new props, the blower and installation I spent $8,000. But when you add up the alternative engine mods, this is not bad. It is more drivable than a normally aspirated "hot" engine too. Feel free to ask any questions about my set up and installation. You should go to the book store and get a supercharger reference book. I read 2 on blowers and 1 on turbos to get different perspectives. There are small differences to each author's beliefs, but the truth is what is common to all of them. I used that to narrow down to Whipple. I was a Procharger fan prior to that.
Originally posted by wally:
What can be done to increase horsepower on this engine? Whipple Superchargers says that this engine is not strong enough to handle extra HP. What needs to be done so that a supercharger can be added?

Laveyman
08-27-2000, 12:38 AM
Rod in CA,
You mentioned you read some books on supercharging. What are their titles? Where did ya get them? I'd like to read them.
I'm also seriously considering installing one on my 99 Lavey this winter. Its got the 454 Mag MPI in it, and I'm not quite so worried about engine problems. With the forged crank and pistons is should be fine. I'm just paranoid about screwing my engines extended warranty.
The guys down at Laveycraft have done several Procharger installs with no problems. However, they have a couple of guys with Whipples that have blown motors also. I've heard this is usually due to improper installs by the boat owners. I've narrowed my choices down to the Whipple, Procharger, or Vortech. Any info or literature you, or anyone out there, can point me towards is greatly appreciated. I've been to all of their websites, and of course, they all say their product is the best. I tend to believe those that have installed one in their own boat more that a company interested in getting my $$$.

Rod in CA
08-29-2000, 05:56 PM
Hello Laveyman,
I moved about a year ago and pack the books into boxes. I can't seem to locate the right box in storage. Sorry! You can do what I did and find various books at Barnes & Nobles, Tower Books, etc. They have large automotive sections and will usually have a smaller section on performance applications. You may try the local speed shop in town to find books on the subject. Mine were all paperback in the 8x11 inch size. The largest was about 100 pages.
To summarize the similarities, all said that heat is the big problem. Since you are taking a pressurized air/fuel mix and cramming it into each cylinder, the overall heat goes up. That is more energy per powerstroke. The heat has to go somewhere. Also complicating this is the process of compression has to add significant heat by the laws of physics. This further adds to the heat problem. Most modern engines can handle this heat by dissipating into cooling jackets, but the problem is DETONATION. Detonation can punch a hole through the superhot piston faster than you can react. You have to ensure that through design you eliminate as much heat as posible and have a strong engine to start with. If you get greedy with boost it will bite you eventually. Other "must haves" are an intercooler. It will reduce air charge by up to 30 degrees and may just be enough to prevent premature fuel ignition or detonation. Octane boosters help but I didn't want that hassle. Mine had to be 92 pump gas.
Engine conciderations are completely different than normally aspirated engines. For example you need LOW compression pistons with a blower. My cheap 7.4 MPI has 9to1 stock - perfect for 5-8 PSI boost. Any higher boost and would have to reduce piston compression ratio. The reason is that you are pushing 2 times the air mix into each cylinder on each stroke (at 7PSI). That compressed air mix is then compressed by the piston 9to1 (in my case). That raises the actual compression to 18to1. This is how detonation occcurs. The excess heat triggers the explosion and not the spark plug. It is dieseling at that point. What is your compression ratio? The 454Mag MPI is alittle higher than mine so you will be limited to a slightly lower max boost than I am but since your heads breath slighty better it should be a wash. The MPI works great with either system. Carbs don't work at all or at least they didn't.
No engine manufacturer will honor a warantee with a blower attached because any bad gas or lean condition or boost pump failure or blocked intercooler, etc., at full power can take an otherwise good installation and grenade the engine.
Another thing is that the Whipple computer monitors fuel pressure and exhuast gas temperature among other things to optimize fuel mixture to stay in the safe zone. Both fuel pressure and EGT are indicated by idiot lights on my dash. Fuel pressure is most important since it is a red light. If it illuminates, you better back off NOW! The EGT is amber in color and requires a power reduction until it turns off. I have had the red light twice. Once was due to water in the boost pump connector and the other was that I had less than 1/8 of a tank of gas and was jumping waves. The fuel port in the tank sucked air as the fuel sloshed around. You really do notice that red light! No damage was done. I reduced power ( the light went out) and got gas at the next pump. I have never had an EGT light which says the system is running cool enough overall.
You mentioned Procharger. Both Pro and Whipple are good quality systems with alot of support. The only significant difference is that Whipple uses a Lysholm (sp?)style compressor that is the most efficient at compression without creating heat. Pro is a centrifugal compressor and is only slightly less efficient. Roots type blowers are very inefficient. It is known as Abdiatic efficiency ( i am probably butchering this term but you will see it in the propaganda each company puts out). I chose the Whipple because it creates boost immediately and that boost is proportional to RPM. The air charge can't backtrack through the blower if it is turning in the correct direction. I mean that as RPM climbs, the boost comes up quickly and so does torque. This helps the engine spin up a big prop without lugging down the engine. The Pro charger is soft power. A cetrifugal compressor relies on air mass accelerating outward inside the impeller to create boost. The impeller spins about 20,000 rpm at full power and that is where it is efficient. Below that RPM the airmass leaks back reducing efficency and ultimately torque. The boost comes on later in the engine power band compared to Whipple. Compare torque curves and you will see the Whipple torque rises quickly and then flattens off toward max RPM. You get max torque below 50% engine RPM The Pro torque rises slowly until about half RPM and then rises quickly to max torque at peak RPM. Since we don't have a clutch to slip in a boat to keep the RPM up, instead we need to spin up the prop at low RPM and Whiple does it well.
Originally posted by Laveyman:
Rod in CA,
You mentioned you read some books on supercharging. What are their titles? Where did ya get them? I'd like to read them.
I'm also seriously considering installing one on my 99 Lavey this winter. Its got the 454 Mag MPI in it, and I'm not quite so worried about engine problems. With the forged crank and pistons is should be fine. I'm just paranoid about screwing my engines extended warranty.
The guys down at Laveycraft have done several Procharger installs with no problems. However, they have a couple of guys with Whipples that have blown motors also. I've heard this is usually due to improper installs by the boat owners. I've narrowed my choices down to the Whipple, Procharger, or Vortech. Any info or literature you, or anyone out there, can point me towards is greatly appreciated. I've been to all of their websites, and of course, they all say their product is the best. I tend to believe those that have installed one in their own boat more that a company interested in getting my $$$.

EWB
10-06-2000, 06:29 PM
Originally posted by Jerry Buckner:
You would need to make sure the engine has forged pistons, a forged crankshaft as opposed to a cast crank and good connecting rods. It would also bennifit from a camshaft upgrade for better breathing and then of course it has to be able to get out so a good exhaust system is a must. CUBIC DOLLARS!
Good luck.

EWB
10-06-2000, 06:46 PM
[QUOTE]Originally posted by wally:
[B]What can be done to increase horsepower on this engine? Whipple Superchargers says that this engine is not strong enough to handle extra HP. What needs to be done so that a supercharger can be added?Hello Walley I have the same engine in my boat Whipple told me the same thing thay told you so I called procharger I have been very pleased with the results I have 51 hours on the engine since I installed it and have had no problems my boat came with a 23p mirage plus after the procharger I now turn a 29p hydromotive q4 @4900 either way procharger or whipple I think either is the way to go on or eigines best of luck!

nuboater
08-11-2002, 12:00 PM
Hey Laveyman did you ever charge up your motor?

KC
08-13-2002, 05:45 AM
Rod... thanks for the great explaination regarding Whipple, I've been considering an engine swap or bolting the Whipple onto my 7.4 MPI... sounds like the Whipple is pretty clean!
KC

need4speed2
08-14-2002, 05:35 AM
hi wally
I have a 97 240 baja with 330 454 thats stock from the heads down.I installed a 250powercharger
dean nickerson stage 5 carb and a small nos plate.
the boat had 86hrs when we installed this set up
It now has 196hrs with no problems .. on lake erie
here the boat runs. 76mph on the motor and 84 on the juice gps ... DEAN NICKERSON has helped me from start to finsh .. He's an ace

KC
08-19-2002, 04:02 PM
I spoke with the folks at whipple about their kit for the 7.4 MPI 310hp, they suggest that the pistons and rods be upgraded - seems the 310hp version is no stronger than the average truck motor.
KC

nuboater
08-21-2002, 11:23 AM
Anyone now what that would cost?