Only made 720 hp with my Whipple??
 

Don't get me wrong here, not complaining, I just thought I would see more than 720 hp. Here's why. Keep in mind, Whipple advertises 740 with their stage 2 kit and a stock engine. Here is what I've got.

Hp500efi, with Dart aluminum heads, port matched to Whipple intake . Stock hp500efi cam. New 502 block deck honed and rotating assembly balanced with all bearings within tight spec. all piston rings special end gap type for specific fit. More about the build here http://www.speedwake.com/upload/show...threadid=53577

so here is the dyno pull. there will be an AFR adjustment once more around the 3000 rpm range to even it out.

So am I wrong to expect more? And again, tons of power, and I know its going to be strong, just wanted to share this with others.

You're unhappy about 20hp? There could be 20hp by simply running it on another dyno.

Personally, I'd let it eat and go have fun.

I agree, hope your drive can take it.

753 ft lbs of torque! Enjoy the engines!

I think 720 is a more real world result than 740 unless you have a good mefi tuner at the dyno. Did you change the compression ratio when you changed the heads.

Could be the cam? A nice blower cam would make a little more. But I dunno if 20hp is worth that much time and money to change cams.

A good tuner can make up 20 hp safely by just watching egt's and making adjustments.......Still respectable power for that package....

Let me be clear, I'm and very happy with the engine. I expected more. The stock kit is suposed to be 740 hp. So with my dart heads and port matching I thought I'd see at least more than 740hp. But I'm still very happy.

Same compresion ratio, and my tuner has recalibrated this engine over 80 times useing the MEFIBURN.COM system. Been over three weeks tuning. There was an issue with the original Whipple calibration perameters. I even bought another computer because we thought mine was fried. Turns out it wasn't.

Thats what my builder told me. He said some dyno's can be manipulated to read more. He doesn't do this. Don't know if thats true or not.

But I repeat, I am happy with this engine.

I think a cam change would easily bring the numbers up and not hurt reliability at all.

I agree.

Now, maybe Dustin at Whipple can chime in here, I wonder if Whipple dyno's without any acxessories? Power steering pump, water pump, ???

There can be so many variances on dynos, calibrations slightly different, weather etc. The stock kit might have dynoed 700 that day.

your heads are much better then stock so the cam is hurting you, with these heads you need more cam. A craine 741 would help and with it you should see in the low 800 range.

It's the torque that will allow you turn a bigger propeller and faster ...prop it accordingly...

You can mess with the correction factor on any dyno and get that sucka to read 850 if ya wanted. I give no credit to the people who do this but there are some.

Great advise!

Totally agree when you are still running the stock cam. It's your weak link to keeping stock number power ranges instead of being higher.

IF (big if) the stock 500efi is able to consistently return 740hp (when corrected for altitude, etc) with the same kit you have installed, then YES you should be pissed off.

The key is the IF.

Bottom line is, your heads SHOULD be good for more hp than the stock heads when run in an apples to apples blower comparison. No bones about it.

We've established that you have BETTER THAN STOCK heads, and stock cam. Now we have questions..

Is the stock cam degreed properly? If not, you're losing power there.
Do the new heads have larger chambers (lower static CR)? If so, then you're losing power, but also have more potential to tolerate more boost without detonating.
Is the port matching and port cleanup an IMPROVEMENT or did he actually HURT your flow? I've seen some PRETTY ports that no longer flowed worth a diggity.
Is your motor set up to clearances that are actually robbing horsepower? If so, it may loosen up with break-in, but I would be a bit frightened if this is the case.

I read your build thread. I have some concerns.
What bearing clearance did he set your motor up to? What thrust clearance? What side clearance? etc. Sounds like he made a lot of wholesale clearance changes.

What rings did he swap you over to? The supplied rings with the JE marine piston are usually decent rings unless you want to go to 2 piece or something. If you use a gapless setup, you have to do a special hone finish. Also, a marine blower motor can stand to have a larger end gap than you would normally run, because if you lose a water pump under boost, you can scuff the cylinders very quickly with tight rings.

Valve guide clearance... What clearance did he set you up to? Exhaust stem clearance NEEDS to be looser than your grandma's Buick.

Best of luck.

Dyno to dyno, you can never expect to get the same reading. I wouldn't worry so much about the actual number. I would like to have seen what your stock motor pulled on THAT dyno for reference.

If if makes you feel any better though, the MATH says that 5 pounds of boost on an apples to apples comparison is only good for a theoretical 36% increase in hp. A 500 horse motor should only make 680 hp with 5 pounds of "perfect" boost (with no added heat).

So, using an adiabatically PERFECT blower (that doesn't add ANY heat to your intake air) pumping 5 psi into your 500 horse motor, assuming that the accessory drive isn't robbing ANY horsepower to spin the blower (which is just as impossible as the perfect boost), then you see 680.

That's what the MATH says.

Reality says that your boost is only at BEST 90% efficient, and your blower probably takes 30hp to spin it.
So you have a 33% (36 x .90) increase (to 665hp) and then take away the 30hp to spin it, and you're down to 635hp.

SO where does the advertised 740 come in?

Well, if you run 40 degree water thru the intercooler, you might be able to pulley up to an effective 7psi, and cool it back to a measured 5psi. This would be some REALLY cold dense intake charge. It would also give you a theoretical 50% boost in power. 500 plus 50% = 750. Take away the 30hp to spin the blower, and you're back to 720hp. Cut all the other belts on the motor and run the right set of dyno headers, and voila, you're back to 740hp.

On the other hand, the advertised test motor may have been exceptionally frisky. It may have been stock (ish) and may have actually belted out 740 that day with no tricks.

When you boil it all down, a measured 720 out of your combo with 5psi of manifold pressure is nothing to piss and moan about.

Like you, I'd wish and wish for those extra imaginary ponies back, but my guess is that the stock motor in the advertisements is just a touch more sprightly than your garden variety stocker.

mc

All the trick parts and a stock cam , seem's a little silly .But you still got lots to trash a bravo. good luck Jeff :cool-smiley-026:

Don't feel bad. I have 575 sci motors with superchillers. First stage upgrade states 650hp with no other mods. With fuel upgrades (aeromotive pumps and return fuel system) and upgrade in pulley (4" to 3 1/4") they state 675-700hp. Well, I have all the upgrades and was dynoed at 652hp/701tq. Oh well, as long as it runs good and I don't eat drives ( I have XR's) I will be happy. Mike

Jesus MC, I had to read that twice. I can't answer all questions, hardly any actualy, But this builder is well established and is known for his head work.

I agree with you that the 740 hp number is going to be on the high side strickly for business reasons.

I'm trusting you on the mathmatical hp number, so that makes me feel good.

Your within 3% of 740HP...Not bad. Thats like 1mph.
The stock cam is not giving you what you have in the heads.

Actually you are with in less than 3% what is advertised. Not being a Engine guru, I would say thats awsome with out spending allot of time making adjustments. My concern would be all the Tolerences that seem to be changed, we all know that adjusting this can rob some HP, if I had to guess that is what happened and once the motor is broke in you will see the 20hp, who knows maybe more??

Really hard to compare a stock 500efi/whipple set up to a 500efi/whipple set up not exactly stock. Cannot tell youhow many times changing something in a engine that should have made more power actually made no gain or less for no real reason???????

My 2 cents:D

WILL

YOur right in the ball park. The cam is restricting you and I would suggest running your CMI headers to get a more true Dyno reading. Dean Gellner (MR. Horsepower) doen all my work and always runs the marine exhaust when tuning.

We wanted to run the CMI's but would have had to make an adapter for his exhaust colector. I decided to not to.

I've got a similair engine in pieces in my shop right now. Stage two with merlin heads and stock cam. The dyno sheets from the "builder" show anywhere from 713hp to one mystery pull that made 789, and a bunch in the 730hp-740hp range. This was over a few days and really shows how much a bad dyno setup or operator can skew results. There were 30hp differences between back to back pulls without any tuning changes. Sometimes just changing the rpm/sec rate of the pull can show unrealistic results. Unfortunately they left the iron guides in without inconels and .0015 clearance. It lasted about 40 seconds at full throttle and grabbed a valve. :hitfan: Enjoy the blower whine.. :evilb:

We run with all the accessories, sea pump with water, power steering, etc. But the problem here is the exhaust system. You can't dyno a 500HP EFI motor with large tube dyno headers. You have to run the stock E-top CMI's. This richens the air fuel ratio well over 10%. You can see the AF is going rich on top when it should hold 12:1. You also have to verify, with a scan tool that the ECM does not retard timing, sometimes on a dyno, the engine vibration and absorber will cause the knock sensor to pickup noise, and therefore retard timing.

You could easily take fuel psi away for a dyno run, but it in fact needs to be setup the way it is in the boat.

Get the AF right and you'll see closer to 750+ HP, but again, it's calibrated for operation in a boat.

Thanks,
Dustin

I just noticed that you have Dart Pro 1 heads. If thats the case, and you DID NOT change the SC pulley, then you've lost almost all velocity through your heads. Those heads flow significantly better, but you need to keep the air speed up. By not changing the blower pulley, you kept airflow exactly the same, yet lowered the compression of the enigne and the temperature of combustion.

Aluminum heads need to be run leaner, they need some cylinder pressure to work properly. Changing to the different heads should allow you to install a 1/2" smaller pulley, which would put the boost up to 8psi, which will net another 50-75hp.

Remember the SC is the pump, if you don't change the speed of the pump, you WILL NOT get more air through the engine, therefore, changing heads to aluminum just lowers combustion temp, higher flowing head just causes loss of velocity, etc.

Put a pulley on it and watch it go.

Dustin

AAHH answer from a GURU, nice:D:evilb:

WILL

The Merlin's won't make as much as the Dart's but because they're still cast iron. The boost doesn't drop as much. But, will make more power if Canada Jeff doesn't change the pulley because they keep combustion temps up.

Thanks,
Dustin

Dustin,

Quick question... Theoretically, if he has better flowing heads than stock wouldn't he make less boost and potentially more power with the same pulley since more air can get into the engine with less resistance? In the end he would make more power with less boost?

Then again...even if the heads flow better, now the cam would be limiting his power output?

Frank

Theoretically, yes, but he went to aluminum heads, which I'm all for, but they lower combustion temp and effictevely make less hp at the same cylinder pressure. But aluminum allows you to run more compression, via more air and fuel, which significatnly compensates for the difference in material. So if you have this motor at stock 8.75:1, then install Darts with the exact same combustion size (typically slightly larger), then the "rule of thumb" compression went down to nearly 7.75:1, yet you have the same airflow through the engine.

He said he has 5psi, the kits normally have 6.5-7psi so he lost 1-1.5psi from heads and port matching. The difference in power for the blower on 1-1.5psi is 3-5hp, so it's almost nothing in the way of restriction. Temp would only be effected 8-10deg F before the IC, after IC, it would be closer to 4-5deg F. Also, when lowering pressure on the inlet side of the valve, less air enters the cylinder. You need pressure to get the 02 in the cylinder.

Thats why I say go to 8psi, and 34 deg timing, or 9psi and 31 deg timing, it will past 800hp and somewhere near 850-875 trq. Right now it has 32deg timing and 5psi when stock, with cast irons, we ran 32 and 6.5psi.

Camshaft is really not much of a restriction at this level except for the 5600-6000rpm range. Ideally, with these heads, and a smaller pulley, I would go bigger, because you can safely run 6000rpm, and with the right cam, there is no question that another 30-50hp is in the motor. If it's all right, a 502ci, with Dart Pro1 heads, our stg2 kit, 8psi, 6000rpm should make 825-850hp on 91 octane fuel.

Thanks,
Dustin

Thanks for the insight Dustin, it's much appreciated!

What's total timing set at on the stage two kit. Or do you program them all differently. I asked the builder what he was running for total and he didn't know, only knew he set it at eight initial. The AFR's were well on the safe side running throught the stock CMI's but the chambers were on fire! and not in a good way :D. This is the first whipple motor I've worked on up here and it is truly an awesome kit!!

32Deg at anything over 5200rpm, 3psi+. Otherwise it's all over the place depending on manifold pressure and rpm.

If I know customer is running aluminum heads, I give it 2degs more timing normally.

Thanks,
Dustin

CHANGE PULLEY!! CHANGE PULLEY!! CHANGE PULLEY!! :D

Just teasing ya.

When you get it in the boat, I would recommend using a wide band AF, preferably from Innovative motorsports. Install on 1/3/5/7 side, at tailpipe, 2" away from flange to collector. Preferably on the side, not on bottom, water drips to the bottom. You'll want it to be 12:1 @ WOT above 5000rpm.

Thanks,
Dustin

Is this side leaner then the other side?

What is better, more boost or more timing? I am guessing and strickly a guess more boost and less timing produces more HP.

Thanks Dustin. Very good information

Great info...

It's extra nice when then man that builds the product is also a OSO member and will take the time to help a brother member. That's why Whipplechargers are top shelf and so is OSO!

this is awesome info for someone looking to do the same thing.
thanks everyone :evilb::cool-smiley-027: