Will the AFR 357cc heads work well???
 

I'm building a 540 tall deck with a whipple quad rotor 2.2L EFI. What do you think of the AFR 357cc CNC heads? Any suggestions for the cam and injector size would also be welcome.

We used the 325 AFR CNC heads on a pair of 540s with a single Whipple. Crane 741 Hyd roller, and 50 lbs. injectors. JE reversed dome pistons. 7 pounds of boost. Idles at 750 rpm and the motors pull hard all the way up to 5600 rpm. Heads are first class. Dont know if they got caught up. It was about 4-6 week wait for a set. Good luck with your quad setup.

We have a set of AFR 357's on the bench ready to go if they are the real deal. I was thinking of a crane 741 with 83Ibs injectors. I plan to run 110 octane and 13Ibs of boost. The goal is 1200HP, or 1000HP on 93 octane.

Well I think the 741 is a good cam but not sure it is enough for what you are trying to build. I know nothing though. :D

I think you will be on the short side with 83 lbs injectors if you are going for 1000-1200 HP.

What is the bore, stroke, rod length on this 540 combo, I will figure the air needed to do so.. .but I think your going to fall short if this is to be a reliable power plant.

chris

Everthing I've seen on the AFR's has been super positive, will be my next head purchase. 83 lb injectors will cut it by turning up the fule pressure, every 10 psi gives another @7lb rating, so just start with extra 10 psi over where they are rated, probably 43 psi, for that kind of HP.

bore 4.50 stoke 4.25 I don't recall the rod length, I will check. It will be 8.25:1 compression.

I'm not sure how reliable any 1000+Hp motor really is...

Assuming it is a 6.385" rod, and target rpm is 5400 max, you need a maximum head flow of 349.87 CFM.

Chris

These heads are solid lifters with stud girdles. The max will be 6500rpm.

Then the CFM needs to be 421.14. If not this will put the blower forcing air through a restriction. "Dirty" air will be a result.

Chris

zt260 110 octane 13 lbs of boost WOW!!!!!

AFR claims they flow at 425CFM depending on lift. Looks like we are in the ballpark.

zt , good luck with it , will be waiting for yourfinal report .......mine is done and being dressed with marine parts this minute . haven't seen final dyno numbers or $$$$$ amount yet ......bob !!!

Fortunately the cam will be chose last. So what cam specs are we talking about? Recommendations anyone???

To make the 1200HP you want, the engine will need to 120% VE at 6500. Cam will be in the .900 lift range and duration in the 290 range @.050. at .400" it will still need to be in the 130 range. Seat duration will be 344.

Chris

He's using a blower and will need to make about 650HP N/A and then use 13 pounds boost will be close to his goal. He doesn't need that big of a cam or rpm.

Marty,
Converting boost to Barometric pressure I then calculated the camshaft. The "throat" area of the intake valve lap will be a restriction, therefore the camshaft will have to over compensate.

Chris

When you double atmospheric pressure ie:14.7 lbs of boost, you @double hp, subtracting out some effeciency factors. He ought to be able to easily make 1200 hp with 13 lbs of boost with a motor that makes 650 NA.

I run 13 lbs of boost with a Procharger and use Canfield 355's, In. flow at .700 is 397, with a .655 lift cam, LSA 114.

Hey guys, it sure is fun jumping on the supercharger threads isn't it?

That engine should easily make 650 HP naturally aspirated. To know how much boost you need, you have to know what the intake air temperature will be after the intercooler, which means you have to know the cooling effectiveness of the core. I don't know the cooling effectiveness of the core in this case, but I can guarantee you will need more than 13 psi to make 1200 HP.

How do I know? Let's assume that the intercooler is 100% effective and the supercharged air is the same temperature as ambient air (impossible but bear with me). Let's also assume that it costs no HP to spin the twin blowers (also impossible).

The density ratio would then be:

(14.7 + 13)/14.7 = 1.88

The new HP level would be:

650 X 1.88 = 1222 HP

That's the best theoretical (and impossible) HP you could get. But since the intake air temperature will be hotter than ambient air, the true air density ratio might only be 1.75. And you have to deduct the power taken off the crank to spin the blowers. So the actual HP might be:

(650 X 1.75) - 40 = 1100 HP

As I said, we don't know the cooling effectiveness, but my guess is you would need 14.7 psi and 90% cooling effectiveness to reach 1200 HP with a 650 HP base engine. You can't beat the Ideal gas law!

I love it when you put the technical spin on the threads with absolute facts, Tomcat, you are the man. I agree with Tomcat, crank up the boost and buy an R-tech cooler.

Solid roller cam in the 250/255 .650/.650 range should be about right.

Greeat big header primary tubes. Dry tailpipes.

Don't need to spin it much over 6,000.

110 octane should let you spin over 12 pounds of boost if you run a high flow cooler, would be my guess.

Keep us informed.

This is the Tech section, let the experiment begin!

Bigger, better intercoolers are one way to improve the overall results, but big heads, cams and exhaust pipes are another, since they reduce the restriction faced by the blower. They also lead you to higher RPM which certainly helps make HP. As a last resort there's race gas.

I like the sound of the engine Beak Boater described. Had to make 650 HP on its on and probably made 850 HP with very reasonable boost. Hydraulic roller, 5600 RPM...beautiful. Of course, I would use a different blower and intercooler and make 1000 HP.:D

Tomcat

Not knowing the true efficiency of the core, plumbing frictional losses and actual hp loss of turning the blower, (at least to start with) is it safe to use the above 100% gas law calculation and subtract say...15% to give you a "close to reality" hp estimate?

I say 15% because the cooler is typically 90%, add another 5% for blower and frictional loss in the average centrifugal SC setup.

DAVE

I think 10% off the ideal calculation would be close for most centrifugal setups. Tthe supercooler setup is about 3.5% off the ideal. These figures are based on dyno tests we have done on blowthrough carb systems, and my observations of the number of elbows I have counted in Procharger installations.

Included in these numbers is the cooling provided by the evaporating fuel. I can believe that this has some effect on intake air density on a blowthrough carb system, but probably not much with port injection. I have heard people say that the carb systems will make a little more power; this may be why.

I hope your project is coming together. I wish I could help out more with it.

Tom

Tom,

Dont worry. You helped plenty. When talking to you on the phone you said a few things that triggered a few ideas that wound up coming together. I'll be getting wet within the next 2 weeks.

Thanks again for your help and info.

DAVE

ZT260,
I just built some motors similar to yours so maybe this will help. Mine are 598ci. 4.5 stroke 4.6 bore 1471 blowers with intercoolers. solid roller cam.Crane #r-260/390-2s-10, which was a Paul Pfaff purchase.Brodix 2X heads with no work done at all. The motors made 1030 HP @ 6400 and 1000 ft/lbs of torque. this was on 91 oct. with 9# of boost and comp of 8.5. Just so you Know it was done at Boyd racing engines in Ok. Which builds all of Big Thunders motors. I am a little concerned about the boost and comp. but Louis said as long as i run 93 oct ,which I always do, I should be fine. Hope this helps, just thought I would give you some real #s to go along with all the theories.

Zt260
Sorry I just realized I gave the grind # instead of the part # which is 13r000097