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Old 01-29-2007, 04:52 PM
  #11  
06_gt
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Default RE: Heads!

Hey everyone im glad with the response that everyone has given me and it has helped me look at it in a different light. I agree that 5000 dollars is alot for sixty hp..lol well i will order my tune for what i got and do a supercharger next year with a clutch.. oh ya off subject just ordered a 4:10 ring and pinion and was wondering if anyone has had good luck with them? Whats you rpm at 60mph? just wondering for driving to car shows. thanx for everything.
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Old 01-29-2007, 11:27 PM
  #12  
steelcomp
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Default RE: Heads!

I don't know who these engine guys are, or what their background is, but I smell fish. To saythe ported heads flow too much for cams is bogus. Besides, there's way too much to a port than just flow numbers. If these guys are jusr going for big bench numbers, they're most likely destroying the shape of the port to do so, and that's completely backwards. There's a right way to do this, and I can just about guarantee you that with a properly ported set of headsand cam upgrade, and a piston designed to work with the chamber, there's plenty more than 60 hp available.
But hey, bolt on a blower and be happy.
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Old 01-29-2007, 11:51 PM
  #13  
CrazyAl
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I disagree.

At a certain point flow becomes pretty much meaningless and other things become the limiting factor--for example, displacement. It may well be that a set of ported heads flows so well (with OEM cams...which are quite good) that there just isn't a need to raise lift or duration.

A friend of mine bought a built engine from JDM...forged rotating assembly, heads, the whole deal. He was wanting to buy new cams. They talked him out of it. If these guys were scam artists, they should have just taken his money for the cams. Instead they charged him LESS money.

Now I completely agree with you that porting for big bench numbers is stupid and the "whole equation" has to be considered. Sometimes a good porting job requires ADDING material in certain places in order to direct flow properly.

But in this case we have an engine that is very well designed from the get-go, and is also fairly small in displacement. Even bone stock, 300 HP out of 4.6L is very good. I know that on350 or 351V8 it was easy to get 100+ HP out of a head and cam swap. But that's not comporable here....we are dealing with less displacement, and our engine already came with very good heads and cams bone-stock. There is a lot less room for improvement becasue our stock technology is already very good. That's why we've got 300 HP stock.

Anyway, ifyou don't buy that, just talk to some of the engine builders yourself and read up on people's experiences on the dyno and at the track. The fact is that with currently available parts, heads + cams just isn't worth that much of a HP gain. Perhaps later on someone will make different heads or cams that will change this. But right now, empirically, there isn't much of a point to it.
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Old 01-30-2007, 12:30 AM
  #14  
06GT4RAD
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Default RE: Heads!

Al took the time to write it all out why I said what I said in my above post. A head swap is not cost effective for the small gain you get from them. That money is without a doubt better spent on FI.

Thanks Al for elaborating on what i said initially.

Richard
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Old 01-30-2007, 03:03 AM
  #15  
steelcomp
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Thanks Al...I am an engine builder. What you say is fundamentally true, butI'm not into fundamentals. People fall into mindsets about what should or shouldn't be, given certain restrictions. That's 90% of the pro's out there, and about 99% of what I read here. How is it that the 5.0L mod engine makes 400hp? (100hp increase over this motor)
ORIGINAL: CrazyAl

I disagree.

At a certain point flow becomes pretty much meaningless and other things become the limiting factor--for example, displacement. It may well be that a set of ported heads flows so well (with OEM cams...which are quite good) that there just isn't a need to raise lift or duration.

A friend of mine bought a built engine from JDM...forged rotating assembly, heads, the whole deal. He was wanting to buy new cams. They talked him out of it. If these guys were scam artists, they should have just taken his money for the cams. Instead they charged him LESS money.

Now I completely agree with you that porting for big bench numbers is stupid and the "whole equation" has to be considered. Sometimes a good porting job requires ADDING material in certain places in order to direct flow properly.

But in this case we have an engine that is very well designed from the get-go, and is also fairly small in displacement. Even bone stock, 300 HP out of 4.6L is very good. I know that on350 or 351V8 it was easy to get 100+ HP out of a head and cam swap. But that's not comporable here....we are dealing with less displacement, and our engine already came with very good heads and cams bone-stock. There is a lot less room for improvement becasue our stock technology is already very good. That's why we've got 300 HP stock.

Anyway, ifyou don't buy that, just talk to some of the engine builders yourself and read up on people's experiences on the dyno and at the track. The fact is that with currently available parts, heads + cams just isn't worth that much of a HP gain. Perhaps later on someone will make different heads or cams that will change this. But right now, empirically, there isn't much of a point to it.
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Old 01-30-2007, 11:58 AM
  #16  
CrazyAl
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The mindset issue is exactly what I was bringing up. A lot of people--myself included--are coming from working on older generation V8s. I have built a great many 350 and 383 Chevys, a couple 454s, and a few 351 Fords (All pushrod V8s). On those engines you could easily get a huge HP gain with a simple cam swap or a head swap. It was no big deal to take an engine from a junkyard that was pushing maybe 200 horses when it was new, bump the compression, add a new manifold, cam, and heads, and POW you'd be at 400 or more no problem.-- and no wonder, the difference between the OEM parts (Designed by GM or Ford back in the 50's and 60's) and the aftermarket parts (Designed in the 90s) was staggering.

A lot of people from "that generation" expect that becasue heads & cams could provide 100 HP on a 5.0 L pushrod motor that they can get the same HP boost from doing the same mods to a 3V modular 4.6. Well, that's not going to happen: partially because our 3V 4.6 was designed very recently and already has a lot of very good design work and parts in it. That's why our 4.6L makes 300 stock while the older 5.0 L made a hair over 200 stock.

Now I will freely admit that I haven't built a 3V modular motor. But pushing more than 350 HP or so out of 4.6 L (any engine)is not easily done--at least when we're talking N/Aand no race gas. If we normalize for displacement, that'd be about the same as breaking 380 HP out of 5.0 L, or breaking 440 on a 350 cu in. Possible? Yes. But not simple.

Now while I haven't built a 3V modular, I have been doing a lot of research. And what I have been hearing from the engine builders, guys who beat me at the strip, and reading in the magazine reviews is that at if you install ported heads and cams and run the car on the dyno (with the parts available right now) you don't get much more HP than the heads alone. The dyno results bear this out. And this makes sense, becasue they are running up against the "displacement wall" where there just isn't room to improve. The cylinder filling is not a problem under the conditions that the motor is being run at. Perhaps things would be different if they were dropping in a new rotating assembly and then pushed up theredline ofthe motor...I would expect to see more HP then. But then we're well into FI territory as far as price is concerned.
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